Article
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Pilocarpine-induced status epilepticus (SE), which results in temporal lobe epilepsy (TLE) in rodents, activates the JAK/STAT pathway. In the current study, we evaluate whether brief exposure to a selective inhibitor of the JAK/STAT pathway (WP1066) early after the onset of SE effects the severity of SE or reduces later spontaneous seizure frequency via inhibition of STAT3-regulated gene transcription. Rats that received systemic WP1066 or vehicle at the onset of SE were continuously video-EEG monitored during SE and for one month to assess seizure frequency over time. Protein and/or mRNA levels for pSTAT3, and STAT3-regulated genes including: ICER, Gabra1, c-myc, mcl-1, cyclin D1, and bcl-xl were evaluated in WP1066 and vehicle-treated rats during stages of epileptogenesis to determine the acute effects of WP1066 administration on SE and chronic epilepsy. WP1066 (two 50mg/kg doses) administered within the first hour after onset of SE results in transient inhibition of pSTAT3 and long-term reduction in spontaneous seizure frequency. WP1066 alters the severity of chronic epilepsy without affecting SE or cell death. Early WP1066 administration reduces known downstream targets of STAT3 transcription 24hours after SE including cyclin D1 and mcl-1 levels, known for their roles in cell-cycle progression and cell survival, respectively. These findings uncover a potential effect of the JAK/STAT pathway after brain injury that is physiologically important and may provide a new therapeutic target that can be harnessed for the prevention of epilepsy development and/or progression.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Studies in post-SE animals have shown significant changes in subunit composition of inhibitory GABAAR's in the DG. Recent investigations into the signaling pathways that underlie these post-SE changes have identified several promising molecular targets for therapies aimed at augmenting inhibitory signaling to halt epileptogenesis or for functional improvement in epilepsy [132]. ...
... The JAK-STAT pathway is activated by a variety of methods, including cytokines binding to their specific receptors, resulting in transphosphorylation of Janus kinases (JAKs) that then lead to phosphorylation of STAT proteins. Protein and/or mRNA levels for pSTAT3, and STAT3-regulated genes were evaluated in WP1066 (STAT3 inhibitor) and vehicle-treated rats during stages of epileptogenesis to determine the acute effects of STAT3 inhibition on chronic epilepsy [132]. Early WP1066 administration reduces known downstream targets of STAT3 transcription, known for their roles in cell-cycle progression and cell survival. ...
... Early WP1066 administration reduces known downstream targets of STAT3 transcription, known for their roles in cell-cycle progression and cell survival. [132]. Following TBI, WP1066 treatment improved the degree of recovery of vestibular motor function after injury. ...
Article
This article describes the recent advances in epileptogenesis and novel therapeutic approaches for the prevention of epilepsy, with a special emphasis on the pharmacological basis of disease-modification of epileptogenesis for curing epilepsy. Here we assess animal studies and human clinical trials of epilepsy spanning 1982–2016. Epilepsy arises from a number of neuronal factors that trigger epileptogenesis, which is the process by which a brain shifts from a normal physiologic state to an epileptic condition. The events precipitating these changes can be of diverse origin, including traumatic brain injury, cerebrovascular damage, infections, chemical neurotoxicity, and emergency seizure conditions such as status epilepticus. Expectedly, the molecular and system mechanisms responsible for epileptogenesis are not well defined or understood. To date, there is no approved therapy for the prevention of epilepsy. Epigenetic dysregulation, neuroinflammation, and neurodegeneration appear to trigger epileptogenesis. Targeted drugs are being identified that can truly prevent the development of epilepsy in at-risk people. The promising agents include rapamycin, COX-2 inhibitors, TRK inhibitors, epigenetic modulators, JAK-STAT inhibitors, and neurosteroids. Recent evidence suggests that neurosteroids may play a role in modulating epileptogenesis. A number of promising drugs are under investigation for the prevention or modification of epileptogenesis to halt the development of epilepsy. Some drugs in development appear rational for preventing epilepsy because they target the initial trigger or related signaling pathways as the brain becomes progressively more prone to seizures. Additional research into the target validity and clinical investigation is essential to make new frontiers in curing epilepsy.
... These activated STAT3 genes are involved in type A GABA receptor subunit modulation, cell survival, cell proliferation, and cell cycling. In the rat pilocarpine paradigm, Grabenstatter et al. discovered that blocking STAT3 phosphorylation during status epilepticus lowered the severity of future seizures (Grabenstatter et al., 2014). These shreds of evidence suggest the partial contribution of status epilepticus induced JAK/STAT activation to the development of chronic epilepsy, i.e., epileptogenesis at later stages. ...
... The reduced expression of the α1 subunit of GABA A receptor was also observed in epilepsy patients (Brooks-Kayal et al., 1998) and other neurological disorders (Bossers et al., 2010;Brooks-Kayal et al., 1998;Raud et al., 2009). Additionally, the JAK/STAT inhibitor WP1066 had been reported to lower the number of spontaneous seizures after the latent phase in the pilocarpine rat model of epilepsy (Grabenstatter et al., 2014). ...
... GABRA is responsible for synthesising the GABA A receptor (the primary source of fast synaptic inhibition in the brain); the aberrant changes in GABA A receptor subunit expression linked to epileptogenesis. (Grabenstatter et al., 2014;Hixson et al., 2019aHixson et al., , 2019bLund et al., 2008;Raible et al., 2014). Apart from the activation of pro-apoptotic genes and BDNF release, other directly reported pathways contributing to epileptogenesis are the mTOR pathway and Wnt pathway. ...
Article
Despite the years of research, epilepsy remains uncontrolled in one-third of afflicted individuals and poses a health and economic burden on society. Currently available anti-epileptic drugs mainly target the excitatory-inhibitory imbalance despite targeting the underlying pathophysiology of the disease. Recent research focuses on understanding the pathophysiologic mechanisms that lead to seizure generation and on possible new treatment avenues for preventing epilepsy after a brain injury. Various signaling pathways, including the mechanistic target of rapamycin (mTOR) pathway, mitogen-activated protein kinase (MAP-ERK) pathway, JAK-STAT pathway, wnt/β-catenin signaling, cAMP pathway, and jun kinase pathway, have been suggested to play an essential role in this regard. Recent work suggests that the mTOR pathway intervenes epileptogenesis and proposes that mTOR inhibitors may have antiepileptogenic properties for epilepsy. In the same way, several animal studies have indicated the involvement of the Wnt signaling pathway in neurogenesis and neuronal death induced by seizures in different phases (acute and chronic) of seizure development. Various studies have also documented the activation of JAK-STAT signaling in epilepsy and cAMP involvement in epileptogenesis through CREB (cAMP response element-binding protein). Although studies are there, the mechanism for how components of these pathways mediate epileptogenesis requires further investigation. This review summarises the current role of various signaling pathways involved in epileptogenesis and the crosstalk among them. Furthermore, we will also discuss the mechanical base for the interaction between these pathways and how these interactions could be a new emerging promising target for future epilepsy therapies.
... We previously reported a similar post-TBI Stat3 upregulation in the dentate gyrus [19]. Several different experimental models show post-injury activation of JAK2-STAT3 pathways [80][81][82][83][84]. Activation of the pathways occurs when JAK2 is phosphorylated. ...
... Inhibiting JAK2 and STAT3 phosphorylation leads to worsened neurologic recovery after TBI [85], while activating phosphorylation with human recombinant erythropoietin reduces post-TBI apoptosis of cortical cells in the rat brain [82]. Grabenstatter et al. (2014) [84] further demonstrated that brief inhibition of STAT3 phosphorylation reduces the frequency of spontaneous seizures in an animal model of temporal lobe epilepsy, suggesting that modulating Stat3 levels through miR-124-3p could mechanistically contribute to post-traumatic epileptogenesis. ...
... Inhibiting JAK2 and STAT3 phosphorylation leads to worsened neurologic recovery after TBI [85], while activating phosphorylation with human recombinant erythropoietin reduces post-TBI apoptosis of cortical cells in the rat brain [82]. Grabenstatter et al. (2014) [84] further demonstrated that brief inhibition of STAT3 phosphorylation reduces the frequency of spontaneous seizures in an animal model of temporal lobe epilepsy, suggesting that modulating Stat3 levels through miR-124-3p could mechanistically contribute to post-traumatic epileptogenesis. ...
Article
Full-text available
Traumatic brain injury (TBI) dysregulates microRNAs, which are the master regulators of gene expression. Here we investigated the changes in a brain-enriched miR-124-3p, which is known to associate with major post-injury pathologies, such as neuroinflammation. RT-qPCR of the rat tissue sampled at 7 d and 3 months in the perilesional cortex adjacent to the necrotic lesion core (aPeCx) revealed downregulation of miR-124-3p at 7 d (fold-change (FC) 0.13, p < 0.05 compared with control) and 3 months (FC 0.40, p < 0.05) post-TBI. In situ hybridization confirmed the downregulation of miR-124-3p at 7 d and 3 months post-TBI in the aPeCx (both p < 0.01). RT-qPCR confirmed the upregulation of the miR-124-3p target Stat3 in the aPeCx at 7 d post-TBI (7-fold, p < 0.05). mRNA-Seq revealed 312 downregulated and 311 upregulated miR-124 targets (p < 0.05). To investigate whether experimental findings translated to humans, we performed in situ hybridization of miR-124-3p in temporal lobe autopsy samples of TBI patients. Our data revealed downregulation of miR-124-3p in individual neurons of cortical layer III. These findings indicate a persistent downregulation of miR-124-3p in the perilesional cortex that might contribute to post-injury neurodegeneration and inflammation.
... Most importantly, reduced α1 subunit gene expression also occurs in epilepsy patients [5] as well as in other disorders of the nervous system [29][30][31]. In addition, use of the JAK/STAT inhibitor, WP1066, in the PILO rat model of epilepsy reduces the number of spontaneous seizures after the latent period [32]. We now hypothesize that in addition to controlling the gene regulation of Gabra1/GABRA1, the BDNF-induced JAK/ STAT pathway controls the expression of diverse gene products that are involved in synaptic plasticity as well as in the epileptogenic process that follows brain injury. ...
... Many of the genes identified in these RNA-seq studies were originally reported by us in the literature (ICER, Gabra1, Egr3), using a variety of molecular approaches [23,32,44]. (Fig. 6). ...
... We also reported that activated CREB interacts with ICER to downregulate the levels of Gabra1 transcripts leading to a decrease in α1-containing GABARs in hippocampal neurons. In our studies, we discovered that BDNF was linked to the JAK/STAT pathway as 1) STAT3 knockdown blocked ICER induction in response to BDNF, 2) STAT3 was found on the ICER promoter in response to BDNF treatment (as measured by chromatin immunoprecipitation (ChIP), 3) JAK/STAT inhibitors (pyridone 6 and WP1066) blocked ICER induction and Gabra1 downregulation, and 4) in vivo application of WP1066 at the time of pilocarpine-induced SE reduced the frequency of subsequent spontaneous seizures in these animals [32]. ...
Article
Full-text available
Background: Brain-derived neurotrophic factor (BDNF) is a major signaling molecule that the brain uses to control a vast network of intracellular cascades fundamental to properties of learning and memory, and cognition. While much is known about BDNF signaling in the healthy nervous system where it controls the mitogen activated protein kinase (MAPK) and cyclic-AMP pathways, less is known about its role in multiple brain disorders where it contributes to the dysregulated neuroplasticity seen in epilepsy and traumatic brain injury (TBI). We previously found that neurons respond to prolonged BDNF exposure (both in vivo (in models of epilepsy and TBI) and in vitro (in BDNF treated primary neuronal cultures)) by activating the Janus Kinase/Signal Transducer and Activator of Transcription (JAK/STAT) signaling pathway. This pathway is best known for its association with inflammatory cytokines in non-neuronal cells. Results: Here, using deep RNA-sequencing of neurons exposed to BDNF in the presence and absence of well characterized JAK/STAT inhibitors, and without non-neuronal cells, we determine the BDNF transcriptome that is specifically regulated by agents that inhibit JAK/STAT signaling. Surprisingly, the BDNF-induced JAK/STAT transcriptome contains ion channels and neurotransmitter receptors coming from all the major classes expressed in the brain, along with key modulators of synaptic plasticity, neurogenesis, and axonal remodeling. Analysis of this dataset has revealed a unique non-canonical mechanism of JAK/STATs in neurons as differential gene expression mediated by STAT3 is not solely dependent upon phosphorylation at residue 705 and may involve a BDNF-induced interaction of STAT3 with Heterochromatin Protein 1 alpha (HP1α). Conclusions: These findings suggest that the neuronal BDNF-induced JAK/STAT pathway involves more than STAT3 phosphorylation at 705, providing the first evidence for a non-canonical mechanism that may involve HP1α. Our analysis reveals that JAK/STAT signaling regulates many of the genes associated with epilepsy syndromes where BDNF levels are markedly elevated. Uncovering the mechanism of this novel form of BDNF signaling in the brain may provide a new direction for epilepsy therapeutics and open a window into the complex mechanisms of STAT3 transcriptional regulation in neurological disease.
... TBI activates a number of signaling pathways that are important for recovery but may also exacerbate injury-related pathology. One of the pathways that has been shown to be activated after several types of cerebral insults, including TBI, is the Janus Kinase/Signal Transducer and Activator of Transcription (JAK/STAT) pathway (Wen et al., 2001, Lund et al., 2008b, Oliva et al., 2011, Zhao et al., 2011a, Zhao et al., 2011b, Raible et al., 2012, Grabenstatter et al., 2013. The JAK/STAT pathway has been shown to regulate the γaminobutyric acid (GABA) type A receptor (GABA A R) subunit α1 expression in the hippocampus by increasing the phosphorylation of STAT3 after the cerebral injury status epilepticus (SE) (Lund et al., 2008a). ...
... The commercially available cell-permeable inhibitor WP1066 (Selleck Chemicals LLC) has been shown to be an effective STAT3 pathway inhibitor (Hussain et al., 2007, Iwamaru et al., 2007, Kupferman et al., 2009, Grabenstatter et al., 2013. This inhibitor has been shown to block the JAK2/STAT3 interaction and subsequent phosphorylation of STAT3 at tyrosine 705 (Faderl et al., 2007). ...
... This inhibitor has been shown to block the JAK2/STAT3 interaction and subsequent phosphorylation of STAT3 at tyrosine 705 (Faderl et al., 2007). WP1066 has also been shown to cross the blood-brain barrier (BBB) and effectively block STAT3 activation after intraperitoneal (i.p.) administration in rodent models of cerebral injuries (Iwamaru et al., 2007, Statler et al., 2009, Grabenstatter et al., 2013. For this study, all operated mice were give i.p. injections of 0.05 ml of dimethyl sulfoxide (DMSO) or 0.05 ml of 75 mg/kg of WP1066 in DMSO 30 and 90 minutes after experimental injury. ...
Article
Synaptic inhibition in the adult brain is primarily mediated by the γ-aminobutyric acid (GABA) type A receptor (GABAAR). The distribution, properties, and dynamics of these receptors are largely determined by their subunit composition. Alteration of subunit composition after a traumatic brain injury (TBI) may result in abnormal increased synaptic firing and possibly contribute to injury-related pathology. Several studies have shown that the Janus Kinase/ Signal Transducer and Activator of Transcription (JAK/STAT) signaling pathway can alter GABAAR subunit expression. The present study investigated changes in JAK/STAT pathway activation after two different severities of experimental TBI in the mouse using the controlled cortical impact (CCI) model. It also investigated whether modulating the activation of the JAK/STAT pathway after severe controlled cortical impact (CCI-S) with a JAK/STAT inhibitor (WP1066) alters post-traumatic epilepsy development and/or neurological recovery after injury. Our results demonstrated differential changes in both the activation of STAT3 and the expression of the GABAAR α1 and γ2 subunit levels that were dependent on the severity of the injury. The change in the GABAAR α1 subunit levels appeared to be at least partly transcriptionally mediated. We were able to selectively reverse the decrease in GABAAR α1 protein levels with WP1066 treatment after CCI injury. WP1066 treatment also improved the degree of recovery of vestibular motor function after injury. These findings suggest that the magnitude of JAK/STAT pathway activation and GABAAR α1 subunit level decrease is dependent on injury severity in this mouse model of TBI. In addition, reducing JAK/STAT pathway activation after severe experimental TBI reverses the decrease in the GABAAR α1 protein levels and improves vestibular motor recovery. Copyright © 2015. Published by Elsevier Inc.
... Each channel for each mouse was inspected using 1D window of Neuroexplorer (Nex Tech, TX) and with reference to the video recordings and hippocampal field oscillatory activities. Voltage-versus-depth profiles, ripples associated with sharp waves, or epileptic patterns ( Fig. 1C-E) were selected using timestamp functions and after the following analysis: Band frequencies for delta (0.1-3.9 Hz), theta (4-8 Hz), beta (13)(14)(15)(16)(17)(18)(19)(20), low gamma (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40), and bands from 100-300 Hz were selected and quantified using power spectral density. Briefly, signal values were multiplied by the coefficients of the Hann window, and discrete fast Fourier transformations of the results were calculated using formulas defined previously [26] and then normalized using Neuroexplorer (Nex Technologies, Madison, AL). ...
... Spontaneous electrographic seizures were identified from LFP background by high amplitude spike activity above 4 SD from the baseline with a frequency above 4 Hz progressive frequency of spiking activity for a minimum of 10 seconds [28], and confirmed by spectrogram analysis (Fig. 1F). These types of discharges were associated with partial seizures or tonic-clonic seizures. ...
Article
Full-text available
Purpose: Limbic epileptogenesis triggers molecular and cellular events that foster the establishment of aberrant neuronal networks that, in turn, contribute to temporal lobe epilepsy (TLE). Here we have examined hippocampal neuronal network activities in the pilocarpine post-status epilepticus model of limbic epileptogenesis and asked whether or not the docosahexaenoic acid (DHA)-derived lipid mediator, neuroprotectin D1 (NPD1), modulates epileptogenesis. Methods: Status epilepticus (SE) was induced by intraperitoneal administration of pilocarpine in adult male C57BL/6 mice. To evaluate simultaneous hippocampal neuronal networks, local field potentials were recorded from multi-microelectrode arrays (silicon probe) chronically implanted in the dorsal hippocampus. NPD1 (570 μg/kg) or vehicle was administered intraperitoneally daily for five consecutive days 24 hours after termination of SE. Seizures and epileptiform activity were analyzed in freely-moving control and treated mice during epileptogenesis and epileptic periods. Then hippocampal dendritic spines were evaluated using Golgi-staining. Results: We found brief spontaneous microepileptiform activity with high amplitudes in the CA1 pyramidal and stratum radiatum in epileptogenesis. These aberrant activities were attenuated following systemic NPD1 administration, with concomitant hippocampal dendritic spine protection. Moreover, NPD1 treatment led to a reduction in spontaneous recurrent seizures. Conclusions: Our results indicate that NPD1 displays neuroprotective bioactivity on the hippocampal neuronal network ensemble that mediates aberrant circuit activity during epileptogenesis. Insight into the molecular signaling mediated by neuroprotective bioactivity of NPD1 on neuronal network dysfunction may contribute to the development of anti-epileptogenic therapeutic strategies.
... Studies have shown that polymorphism in many related genes is associated with the development of epilepsy, such as GABBR1 8 , ALDH2 9 , and TIMP4 10 . It has been reported that the signal transducer and activator of transcription 3 (STAT3) played a role in the epilepsy of a rat model 11 . However, few studies focused on the effect of STAT3 in epilepsy patients, as well as the polymorphism of STAT3 in epilepsy patients. ...
... Immunohistochemistry was carried out as described previously 11 . Briefly, the brain tissues were collected and fixed in 10% buffered formalin after resection, Samples were then sectioned and spread, followed by deparaffinized, hydrated and incubated in 0.3% H 2 O 2 for 15 min. ...
Article
Objective: To investigate the effect of single nucleotide polymorphisms (SNPs) of signal transducer and activator of transcription 3 (STAT3) on epilepsy in children. Patients and methods: A total of 169 children suffering from epilepsy admitted in No. 1 People's Hospital of Jining from July 2015 to December 2016 were enrolled as the research subjects. Immunohistochemistry and real time-PCR were used for analysis of the expression of STAT3 and p-STAT3 in epilepsy patients. The genotypes and alleles of rs1053005 and re744166 were analyzed through polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Statistical analysis was conducted to explore the correlation between the polymorphism of STAT3 and the incidence of epilepsy in children, and the polymorphism of STAT3 in the drug-resistant and non-resistant patients was compared. Results: Both the STAT3 and p-STAT3 were over-expressed in epilepsy patients. The GG genotype of rs1053005 was significantly lower in epilepsy patients than that of health control, p<0.05. By contrast, no significant difference was found in genotypes of rs744166 between epilepsy and healthy children. When comparing the genotypes of drug-resistant patients and that of non-resistant patients, the distribution of rs1053005 genotypes in the two groups showed a significant difference, p<0.05. No statistical difference was observed in rs744166 genotypes. Conclusions: STAT3 polymorphism was associated with the risk of epilepsy and drug resistance to epilepsy. This study may provide a better understanding of STAT3 in epilepsy patients and provide new targets for the treatment of epilepsy patients.
... have been associated with epilepsy. [49][50][51] FGFR3 mutations are associated with bilateral medial temporal lobe anomalies and focal epilepsy 50 and inhibition of STAT3 was found to diminish seizures in pilocarpine-induced SE. 49 We further found that miR-181a-5p also targets SOCS2. SOCS proteins provide a negative feedback for cytokine interaction and have been previously implicated in epilepsy. ...
... have been associated with epilepsy. [49][50][51] FGFR3 mutations are associated with bilateral medial temporal lobe anomalies and focal epilepsy 50 and inhibition of STAT3 was found to diminish seizures in pilocarpine-induced SE. 49 We further found that miR-181a-5p also targets SOCS2. SOCS proteins provide a negative feedback for cytokine interaction and have been previously implicated in epilepsy. ...
Article
Full-text available
Epilepsy is a chronic brain disease characterized by recurrent seizures. Circular RNA (circRNA) is a novel family of endogenous non‐coding RNAs that have been proposed to regulate gene expression. However, there is a lack of data on the role of circRNA in epilepsy. In this study, the circRNA profiles were evaluated by microarray analysis. In total, 627 circRNAs were up‐regulated, whereas 892 were down‐regulated in the hippocampus in mice with kainic acid (KA)‐induced epileptic seizures compared with control. The expression of circHivep2 was significantly down‐regulated in hippocampus tissues of mice with KA‐induced epileptic seizures and BV‐2 microglia cells upon KA treatment. Bioinformatics analysis predicted that circHivep2 interacts with miR‐181a‐5p to regulate SOCS2 expression, which was validated using a dual‐luciferase reporter assay. Moreover, overexpression of circHivep2 significantly inhibited KA‐induced microglial activation and the expression of inflammatory factors in vitro, which was blocked by miR‐181a‐5p, whereas circHivep2 knockdown further induced microglia cell activation and the release of pro‐inflammatory proteins in BV‐2 microglia cells after KA treatment. The application of circHivep2+ exosomes derived from adipose‐derived stem cells (ADSCs) exerted significant beneficial effects on the behavioural seizure scores of mice with KA‐induced epilepsy compared to control exosomes. The circHivep2+ exosomes also inhibited microglial activation, the expression of inflammatory factors, and the miR‐181a‐5p/SOCS2 axis in vivo. Our results suggest that circHivep2 regulates microglia activation in the progression of epilepsy by interfering with miR‐181a‐5p to promote SOCS2 expression, indicating that circHivep2 may serve as a therapeutic tool to prevent the development of epilepsy.
... Most importantly, reduced 1 subunit gene expression also occurs in epilepsy patients (5) as well as in other disorders of the nervous system (27)(28)(29). In addition, use of the JAK/STAT inhibitor, WP1066, in the PILO rat model of epilepsy reduces the number of spontaneous seizures after the latent period (30). We now hypothesize that in addition to controlling the gene regulation of Gabra1/GABRA1, the BDNF-induced JAK/STAT pathway controls the expression of diverse gene products that are involved in synaptic plasticity as well as in the epileptogenic process that follows brain injury. ...
... Many of the genes identified in these RNA-seq studies were originally reported by us in the literature (ICER, Gabra1, Egr3), using a variety of molecular approaches (23,30,42). To further validate the new datasets, we generated an additional set of cultures, originating from the embryos of multiple Figure 6E. ...
Preprint
Background Brain-derived neurotrophic factor (BDNF) is a major signaling molecule that the brain uses to control a vast network of intracellular cascades fundamental to properties of learning and memory, and cognition. While much is known about BDNF signaling in the healthy nervous system where it controls the mitogen activated protein kinase (MAPK) and cyclic-AMP pathways, less is known about its role in multiple brain disorders where it contributes to the dysregulated neuroplasticity seen in epilepsy and traumatic brain injury (TBI). We previously found that neurons respond to prolonged BDNF exposure (both in vivo (in models of epilepsy and TBI) and in vitro (in BDNF treated primary neuronal cultures)) by activating the Janus Kinase/Signal Transducer and Activator of Transcription (JAK/STAT) signaling pathway. This pathway is best known for its association with inflammatory cytokines in non-neuronal cells. Results Here, using deep RNA-sequencing of neurons exposed to BDNF in the presence and absence of well characterized JAK/STAT inhibitors, and without non-neuronal cells, we determine the BDNF transcriptome that is specifically reliant on JAK/STAT signaling. Surprisingly, the transcriptome contains ion channels and neurotransmitter receptors coming from all the major classes expressed in the brain, along with key modulators of synaptic plasticity, neurogenesis, and axonal remodeling. Analysis of this dataset has also provided a window on the unique mechanism of JAK/STATs in neurons as differential gene expression mediated by STAT3 does not appear to be dependent upon phosphorylation at residue 705. Conclusions Our findings strengthen and expand the role that BDNF plays in the regulation of brain excitability at the transcriptional level. They also suggest that a majority of such signaling in neurons is tied to the activation of the JAK/STAT pathway which may be non-canonical, not based on phosphorylation of STAT3 proteins at Tyrosine 705.
... To further investigate the role of ROCK2 in regulation of epileptogenesis, we determined the downstream targets in SE rat model. JAK/Stat3 pathway was previously shown constitutively activated during brain injuries like SE, and plays a key role in epilepsy development 30,31 . In the present study, we observed the phosphorylation and activation of Stat3 following SE. ...
... The transcription factor Stat3 is known to have important roles in regulating gene expression, speci cally increasing genes important to cell proliferation and cell cycle progression 31,45 51 . In the present study, we con rmed that the Racine scale score of the Fasudil treatment group was signi cantly lower than that of the PiLo group. ...
Preprint
Full-text available
Patients with temporal lobe epilepsy (TLE) are prone to tolerance to antiepileptic drugs. Based on the perspective of molecular targets for drug resistance, it is necessary to explore effective drug resistant genes and signaling pathways for the treatment of TLE. We performed gene expression profiles in hippocampus of patients with drug-resistant TLE and identified ROCK2 as one of the 20 most significantly increased genes in hippocampus. In vitro and in vivo experiments were performed to identify the potential role of ROCK2 in epileptogenesis. In addition, the activity of Stat3 pathway was tested in hippocampal tissues and primary cultured astrocytes. The expression levels of ROCK2 in the hippocampus of TLE patients were significantly increased compared with the control group, which was due to the hypomethylation of ROCK2 promoter. Fasudil, a specific Rho-kinase inhibitor, alleviated epileptic seizures in the pilocarpine rat model of TLE. Furthermore, ROCK2 activated the Stat3 pathway in pilocarpine-treated epilepsy rats, and the spearman correlation method confirmed that ROCK2 is associated with Stat3 activation in TLE patients. In addition, ROCK2 was predominantly expressed in astrocytes during epileptogenesis, and induced epileptogenesis by activating astrocyte cell cycle progression via Stat3 pathway. The overexpressed ROCK2 plays an important role in the pathogenesis of drug-resistant epilepsy. ROCK2 accelerates astrocytes cell cycle progression via the activation of Stat3 pathway likely provides the key to explaining the process of epileptogenesis.
... The JAK/STAT pathway has been shown to be a critical mediator of LTD, 12 and is known to be activated after many types of epileptogenic injuries including TBI, SE, HI, and stroke. [13][14][15] The JAK/STAT pathway regulates expression of genes critical for essential physiologic functions, including cell proliferation, differentiation, neurogenesis, learning and memory, and regulation of the c-aminobutyric acid (GABA) type A receptor (GABA A R) subunit expression. JAK/STAT-mediated decreases in a1 subunit-containing GABA A Rs in hippocampus have been demonstrated after experimental SE and TBI, [14][15][16] and are thought to contribute to hippocampal hyperexcitability after injury and subsequent epileptogenesis. ...
... [13][14][15] The JAK/STAT pathway regulates expression of genes critical for essential physiologic functions, including cell proliferation, differentiation, neurogenesis, learning and memory, and regulation of the c-aminobutyric acid (GABA) type A receptor (GABA A R) subunit expression. JAK/STAT-mediated decreases in a1 subunit-containing GABA A Rs in hippocampus have been demonstrated after experimental SE and TBI, [14][15][16] and are thought to contribute to hippocampal hyperexcitability after injury and subsequent epileptogenesis. ...
Article
Neurologic and psychiatric comorbidities are common in patients with epilepsy. Diagnostic, predictive, and pharmacodynamic biomarkers of such comorbidities do not exist. They may share pathogenetic mechanisms with epileptogenesis/ictogenesis, and as such are an unmet clinical need. The objectives of the subgroup on biomarkers of comorbidities at the XIII Workshop on the Neurobiology of Epilepsy (WONOEP) were to present the state-of-the-art recent research findings in the field that highlighting potential biomarkers for comorbidities in epilepsy. We review recent progress in the field, including molecular, imaging, and genetic biomarkers of comorbidities as discussed during the WONOEP meeting on August 31-September 4, 2015, in Heybeliada Island (Istanbul, Turkey). We further highlight new directions and concepts from studies on comorbidities and potential new biomarkers for the prediction, diagnosis, and treatment of epilepsy-associated comorbidities. The activation of various molecular signaling pathways such as the "Janus Kinase/Signal Transducer and Activator of Transcription," "mammalian Target of Rapamycin," and oxidative stress have been shown to correlate with the presence and severity of subsequent cognitive abnormalities. Furthermore, dysfunction in serotonergic transmission, hyperactivity of the hypothalamic-pituitary-adrenocortical axis, the role of the inflammatory cytokines, and the contributions of genetic factors have all recently been regarded as relevant for understanding epilepsy-associated depression and cognitive deficits. Recent evidence supports the utility of imaging studies as potential biomarkers. The role of such biomarker may be far beyond the diagnosis of comorbidities, as accumulating clinical data indicate that comorbidities can predict epilepsy outcomes. Future research is required to reveal whether molecular changes in specific signaling pathways or advanced imaging techniques could be detected in the clinical settings and correlate with epilepsy-associated comorbidities. A reliable biomarker will allow a more accurate diagnosis and improved treatment of epilepsy-associated comorbidities.
... According to previous evidence, it is crucial to regulate angiogenesis to control vascular remodelling triggered by damage. Therefore, endogenous angio-suppressive factors such as TSP-1, DSCR-1 protein and VASH1 constitute therapeutic targets for modulating vascular remodelling [6] pilo-induced TLE model, in which the inhibition of the JAK/STAT3 pathway, which promotes angiogenesis through Epo-induced VEGF expression, was found to reduce the frequency of spontaneous seizures without inducing neuronal death [128]. However, there 18 is still no evidence of such modulation in patients with TLE. ...
... The studies summarized here show that Epo and VEGF (individually or together) exert important neuroprotective and neurorestorative effects and indicate that these cytokines may become useful therapeutic approaches for various neurological diseases, especially stroke, epilepsy and AD, as discussed in this review. However, more studies are needed to identify specific ways to minimize or eliminate the known side effects of both cytokines, such as tumour growth [173,174], deregulated angiogenesis [126,128,173,174] and drug resistance [91,174,175]. Hence, new molecules with anti-angiogenic [176,177], anti-tumour [178,179] or Epo-and VEGF-blocking effects [168,[178][179][180][181] should be assessed in neurological diseases. ...
Article
Background Erythropoietin (Epo) and vascular endothelial growth factor (VEGF) are two vasoactive molecules with essential trophic effects for brain development. The expression and secretion of both molecules increase in response to neuronal damage and they exert protective and restorative effects, which may also be accompanied by adverse side effects. Objective We review the most relevant evidence on the neuroprotective and neurorestorative effects of Epo and VEGF in three of the most frequent neurological disorders, namely, stroke, epilepsy and Alzheimer's disease, to develop new therapeutic approaches. Method Several original scientific manuscripts and reviews that have discussed the evidence in critical way, considering both the beneficial and adverse effects of Epo and VEGF in the selected neurological disorders, were analysed. In addition, throughout this review, we propose several considerations to take into account in the design of therapeutic approaches based on Epo and VEGF signalling. Results Although the three selected disorders are triggered by different mechanisms, they evolve through similar processes: excitotoxicity, oxidative stress, neuroinflammation, neuronal death, glial reactivity and vascular remodelling. Epo and VEGF exert neuroprotective and neurorestorative effects by acting on these processes due to their pleiotropism. In general, the evidence shows that both Epo and VEGF reduce neuronal death but that at the vascular level, their effects are contradictory. Conclusion Because the Epo and VEGF signalling pathways are connected in several ways, we conclude that more experimental studies, primarily studies designed to thoroughly assess the functional interactions between Epo and VEGF in the brain under both physiological and pathophysiological conditions, are needed.
... The JAK/STAT pathway is upregulated in pilocarpine-or kainite-induced status epilepticus, which results in temporal lobe epilepsy in rodents (Choi et al., 2003;Xu et al., 2011). Administration of the JAK/STAT inhibitor, WP1066, reduces the severity of pilocarpine-induced seizure and downregulates downstream target transcripts of JAK/STAT, including cyclin D1 (Grabenstatter et al., 2014). Our findings raise the possibility that seizure induction results in activation of JAK/STAT signalling, through regulation of cyclin/CDK expression. ...
... mTOR is a serine/threonine kinase involved in the highly conserved PI3K-Akt signalling pathway. It has recently been reported that hyperactivation of mTOR signalling is followed by seizure induction in rat and mouse models (Waltereit et al., 2006;Grabenstatter et al., 2014). ...
Article
Full-text available
Seizure can result from increased voltage-gated persistent sodium current expression. Although many clinically-approved antiepileptic drugs target voltage-gated persistent sodium current, none exclusively repress this current without also adversely affecting the transient voltage-gated sodium current. Achieving a more selective block has significant potential for the treatment of epilepsy. Recent studies show that voltage-gated persistent sodium current amplitude is regulated by alternative splicing offering the possibility of a novel route for seizure control. In this study we identify 291 splicing regulators that, on knockdown, alter splicing of the Drosophila voltage-gated sodium channel to favour inclusion of exon K, rather than the mutually exclusive exon L. This change is associated with both a significant reduction in voltage-gated persistent sodium current, without change to transient voltage-gated sodium current, and to rescue of seizure in this model insect. RNA interference mediated knock-down, in two different seizure mutants, shows that 95 of these regulators are sufficient to significantly reduce seizure duration. Moreover, most suppress seizure activity in both mutants, indicative that they are part of well conserved pathways and likely, therefore, to be optimal candidates to take forward to mammalian studies. We provide proof-of-principle for such studies by showing that inhibition of a selection of regulators, using small molecule inhibitors, is similarly effective to reduce seizure. Splicing of the Drosophila sodium channel shows many similarities to its mammalian counterparts, including altering the amplitude of voltage-gated persistent sodium current. Our study provides the impetus to investigate whether manipulation of splicing of mammalian voltage-gated sodium channels may be exploitable to provide effective seizure control. © The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain.
... The elevated levels of cytokines (TNF-α, IL-6, IL-1β) cause secondary development of seizures that are adversely associated with neuronal apoptosis by activating JAK-STAT in glial cells favoring neuroinflammation in epilepsy [32,61]. Activation of JAK/STAT pathway illustrates an overview of the mechanism of increased neuronal stress with progressive ultrastructural alteration of mitochondrial dysfunction promoting apoptosis with increased Bcl-2 apoptotic protein enduring apoptotic neuronal death under the prolonged seizures-induced CNS insult [62][63][64]. The pre-clinical findings uncover an activation of the JAK/STAT pathway under excessively prolonged seizures induced neuronal injury and likely to be involved in causing neurodegeneration in epilepsy. ...
... The correlation of the JAK/STAT pathway with mitochondrial dysfunction was screened using WP1066, an inhibitor of the JAK/STAT pathway that resulted in the prevention of the development of epileptic seizures in rodents [64]. Therefore, the present target STAT3 tends to be involved in mitochondrial oxidative stress in epilepsy, as concluded by the decreased levels of pro-survival proteins Mcl-1 mRNA, Bcl-xl, c-myc mRNA that regulates mitochondrial function, which gets decreased under chronic epileptic seizures [62]. Therefore, targeting STAT3 tends to be an effective strategy in preventing epileptic seizures and providing the mechanism of mitochondrial dysfunction under prolonged repetitive epileptic seizures mediating apoptotic death in Epilepsy. ...
Article
Full-text available
IntroductionMitochondrial dysfunction is a common denominator of neuroinflammation recognized by neuronal oxidative stress-mediated apoptosis that is well recognized by common intracellular molecular pathway-interlinked neuroinflammation and mitochondrial oxidative stress, a feature of epileptogenesis. In addition, the neuronal damage in the epileptic brain corroborated the concept of brain injury-mediated neuroinflammation, further providing an interlink between inflammation, mitochondrial dysfunction, and oxidative stress in epilepsy.Materials and methodsA systematic literature review of Bentham, Scopus, PubMed, Medline, and EMBASE (Elsevier) databases was carried out to provide evidence of preclinical and clinically used drugs targeting such nuclear, cytosolic, and mitochondrial proteins suggesting that the correlation of mechanisms linked to neuroinflammation has been elucidated in the current review. Despite that, the evidence of elevated levels of inflammatory mediators and pro-apoptotic protein levels can provide the correlation of inflammatory responses often concerned with hyperexcitability attributing to the fact that mitochondrial redox mechanisms and higher susceptibilities to neuroinflammation result from repetitive recurring epileptic seizures. Therefore, providing an understanding of seizure-induced pathological changes read by activating neuroinflammatory cascades like NF-kB, RIPK, MAPK, ERK, JNK, and JAK-STAT signaling further related to mitochondrial damage promoting hyperexcitability.Conclusion The current review highlights the further opportunity for establishing therapeutic interventions underlying the apparent correlation of neuroinflammation mediated mitochondrial oxidative stress might contribute to common intracellular mechanisms underlying a future prospective of drug treatment targeting mitochondrial dysfunction linked to the neuroinflammation in epilepsy.
... STAT3 is mainly localized in the nuclei of reactive astrocytes [56]. Most interestingly, Grabenstatter et al. [83] showed that administering a propenamide analog, WP1066, which is a weak inhibitor of the Jak/STAT pathway, reduces the frequency and severity of spontaneous seizures developing after pilocarpine-induced brain injury. They also reported that WP1066 alleviates a decrease in GABA(A) R α1 protein levels after controlled cortical impact (CCI)induced TBI. ...
Article
Full-text available
Traumatic brain injury (TBI) initiates molecular and cellular pathologies that underlie post-injury morbidities, including hippocampus-related memory decline and epileptogenesis. Non-coding small RNAs are master regulators of gene expression with the potential to affect multiple molecular pathways. To evaluate whether hippocampal gene expression networks are chronically regulated by microRNAs after TBI, we sampled the dentate gyrus of rats with severe TBI induced by lateral fluid-percussion injury 3 months earlier. Ingenuity pathway analysis revealed 30 upregulated miR-124-3p targets, suggesting that miR-124-3p is downregulated post-TBI (z-score = − 5.146, p < 0.05). Droplet digital polymerase chain reaction (ddPCR) and in situ hybridization confirmed the chronic downregulation of miR-124-3p (p < 0.05). Quantitative PCR analysis of two targets, Plp2 and Stat3, indicated that their upregulation correlated with the miR-124-3p downregulation (r = − 0.647, p < 0.05; r = − 0.629, p < 0.05, respectively). Immunohistochemical staining of STAT3 confirmed the increased protein expression. STRING analysis showed that 9 of the 30 miR-124-3p targets belonged to a STAT3 network. Reactome analysis and data mining connected the targets especially to inflammation and signal transduction. L1000CDS2 software revealed drugs (e.g., importazole, trichostatin A, and IKK-16) that could reverse the observed molecular changes. The translational value of our data was emphasized by in situ hybridization showing chronic post-traumatic downregulation of miR-124-3p in the dentate gyrus of TBI patients. Analysis of another brain injury model, status epilepticus, highlighted the fact that chronic downregulation of miR-124 is a common phenomenon after brain injury. Together, our findings indicate that miR-124-3p is a chronic modulator of molecular networks relevant to post-injury hippocampal pathologies in experimental models and in humans.
... Consequently, dysregulation of the JAK-S TA T pathway is at the heart of most brain disorders, including glioma, lesions, ischemia, neurodegenerative disorders, and epilepsies. (40). ...
Article
Background: We recently reported TRIM8, encoding an E3 ubiquitin ligase, as a gene aberrantly expressed in glioblastoma whose expression suppresses cell growth and induces a significant reduction of clonogenic potential in glioblastoma cell lines. Methods: we provided novel insights on TRIM8 functions by profiling the transcriptome of TRIM8-expressing primary mouse embryonal neural stem cells by RNA-sequencing and bioinformatic analysis. Functional analysis including luciferase assay, western blot, PCR arrays, Real time quantitative PCR were performed to validate the transcriptomic data. Results: Our study identified enriched pathways related to the neurotransmission and to the central nervous system (CNS) functions, including axonal guidance, GABA receptor, Ephrin B, synaptic long-term potentiation/depression, and glutamate receptor signalling pathways. Finally, we provided additional evidence about the existence of a functional interactive crosstalk between TRIM8 and STAT3. Conclusions: Our results substantiate the role of TRIM8 in the brain functions through the dysregulation of genes involved in different CNS-related pathways, including JAK-STAT. General significance: This study provides novel insights on the physiological TRIM8 function by profiling for the first time the primary Neural Stem Cell over-expressing TRIM8 by using RNA-Sequencing methodology.
... In addition, the Janus kinase (JAK)-signal transducers and activators of transcription (STAT) transcriptional pathway is activated during epileptogenesis and modifies the expression of genes involved in the cell cycle and survival. Inhibition of the JAK-STAT pathway decreases the severity of epilepsy in rats 61 . Other transcriptomic alterations have been described in epilepsy, although the consequence of these is poorly understood (FIG. ...
Article
Epilepsy affects all age groups and is one of the most common and most disabling neurological disorders. The accurate diagnosis of seizures is essential as some patients will be misdiagnosed with epilepsy, whereas others will receive an incorrect diagnosis. Indeed, errors in diagnosis are common, and many patients fail to receive the correct treatment, which often has severe consequences. Although many patients have seizure control using a single medication, others require multiple medications, resective surgery, neuromodulation devices or dietary therapies. In addition, one-third of patients will continue to have uncontrolled seizures. Epilepsy can substantially impair quality of life owing to seizures, comorbid mood and psychiatric disorders, cognitive deficits and adverse effects of medications. In addition, seizures can be fatal owing to direct effects on autonomic and arousal functions or owing to indirect effects such as drowning and other accidents. Deciphering the pathophysiology of epilepsy has advanced the understanding of the cellular and molecular events initiated by pathogenetic insults that transform normal circuits into epileptic circuits (epileptogenesis) and the mechanisms that generate seizures (ictogenesis). The discovery of >500 genes associated with epilepsy has led to new animal models, more precise diagnoses and, in some cases, targeted therapies.
... The JAK/STAT pathway is up-regulated in both pilocarpine-and kainite-induced status epilepticus (Choi et al., 2003;Xu et al., 2011). Administration of the JAK/STAT inhibitor, WP1066, reduces the severity of pilocarpineinduced seizure and altered JAK/STAT downstream target transcript expression (Grabenstatter et al., 2014). ...
Article
Full-text available
Despite availability of a diverse range of anti-epileptic drugs (AEDs), only about two-thirds of epilepsy patients respond well to drug treatment. Thus, novel targets are required to catalyse the design of next-generation AEDs. Manipulation of neuron firing-rate homoeostasis, through enhancing Pumilio (Pum) activity, has been shown to be potently anticonvulsant in Drosophila. In this study, we performed a genome-wide RNAi screen in S2R + cells, using a luciferase-based dPum activity reporter and identified 1166 genes involved in dPum regulation. Of these genes, we focused on 699 genes that, on knock-down, potentiate dPum activity/expression. Of this subgroup, 101 genes are activity-dependent based on comparison with genes previously identified as activity-dependent by RNA-sequencing. Functional cluster analysis shows these genes are enriched in pathways involved in DNA damage, regulation of cell cycle and proteasomal protein catabolism. To test for anticonvulsant activity, we utilised an RNA-interference approach in vivo. RNAi-mediated knockdown showed that 57/101 genes (61%) are sufficient to significantly reduce seizure duration in the characterized seizure mutant, parabss. We further show that chemical inhibitors of protein products of some of the genes targeted are similarly anticonvulsant. Finally, to establish whether the anticonvulsant activity of identified compounds results from increased dpum transcription, we performed a luciferase-based assay to monitor dpum promoter activity. Third instar larvae exposed to sodium fluoride, gemcitabine, metformin, bestatin, WP1066 or valproic acid all showed increased dpum promoter activity. Thus, this study validates Pum as a favourable target for AED design and, moreover, identifies a number of lead compounds capable of increasing the expression of this homeostatic regulator.
... This analysis also supports the evidence that STAT-3 is the major downstream effector to the altered cytokine signalling cascade. Studies in rat model demonstrated that systemic administration of WP1066, a STAT-3 inhibitor, transiently reduce seizure-induced STAT3 in vivo and also lower the seizure frequencies over time 39 . Thus, STAT3 can be considered as a potential therapeutic target for both HS and FCD and needs further investigations. ...
Article
Full-text available
Experimental and clinical evidence have demonstrated aberrant expression of cytokines/chemokines and their receptors in patients with hippocampal sclerosis (HS) and focal cortical dysplasia (FCD). However, there is limited information regarding the modulation of cytokine/chemokine-regulatory networks, suggesting contribution of miRNAs and downstream transcription factors/receptors in these pathologies. Hence, we studied the levels of multiple inflammatory mediators (IL1β, IL1Ra, IL6, IL10, CCL3, CCL4, TNFα and VEGF) along with transcriptional changes of nine related miRNAs and mRNA levels of downstream effectors of significantly altered cytokines/chemokines in brain tissues obtained from patients with HS (n = 26) and FCD (n = 26). Up regulation of IL1β, IL6, CCL3, CCL4, STAT-3, C-JUN and CCR5, and down regulation of IL 10 were observed in both HS and FCD cases (p < 0.05). CCR5 was significantly up regulated in FCD as compared to HS (p < 0.001). Both, HS and FCD presented decreased miR-223-3p, miR-21-5p, miR-204-5p and let-7a-5p and increased miR-155-5p expression (p < 0.05). As compared to HS, miR-204-5p (upstream to CCR5 and IL1β) and miR-195-5p (upstream to CCL4) were significantly decreased in FCD patients (p < 0.01). Our results suggest differential alteration of cytokine/chemokine regulatory networks in HS and FCD and provide a rationale for developing pathology specific therapy.
... JAK/STAT signal pathway plays a vital role in the differentiation and proliferation of astrocytes, and the proliferation of astrocytes is an important pathological change in the brain tissue of epileptic patients. In the temporal lobe epilepsy rat model, the JAK2/STAT3 signaling pathway is activated, and the using JAK2/STAT3 specific inhibitor WP 1066 can reduce the frequency and severity of the occurrence of epilepsy [17]. Another study showed that the specific blocking JAK2/STAT3 pathway could significantly inhibited the expression of synaptic protein in temporal lobe epilepsy model rats' hippocampus, regulating the hippocampal synaptic plasticity and played an important antiepileptic role [18]. ...
... JAK/STAT mediates decreases in a1 subunit-containing GABA A receptors in hippocampus that occur after experimental SE and TBI 247,249 and may contribute to the increased hyperexcitability observed in the hippocampus of injured animals and to subsequent development of epilepsy. Inhibition of STAT3 phosphorylation after SE-induced brain injury reduces the severity of subsequent epilepsy in the rat pilocarpine model, 253 suggesting that JAK-STAT activation after SE may contribute to epileptogenesis. In the CCI model of PTE in mice, the JAK/STAT pathway is differentially activated depending on the severity of brain injury, and correlates with the presence and severity of subsequent cognitive comorbidities. ...
Article
Full-text available
The most common forms of acquired epilepsies arise following acute brain insults such as traumatic brain injury, stroke, or central nervous system infections. Treatment is effective for only 60%-70% of patients and remains symptomatic despite decades of effort to develop epilepsy prevention therapies. Recent preclinical efforts are focused on likely primary drivers of epileptogenesis, namely inflammation, neuron loss, plasticity, and circuit reorganization. This review suggests a path to identify neuronal and molecular targets for clinical testing of specific hypotheses about epileptogenesis and its prevention or modification. Acquired human epilepsies with different etiologies share some features with animal models. We identify these commonalities and discuss their relevance to the development of successful epilepsy prevention or disease modification strategies. Risk factors for developing epilepsy that appear common to multiple acute injury etiologies include intracranial bleeding, disruption of the blood-brain barrier, more severe injury, and early seizures within 1 week of injury. In diverse human epilepsies and animal models, seizures appear to propagate within a limbic or thalamocortical/corticocortical network. Common histopathologic features of epilepsy of diverse and mostly focal origin are microglial activation and astrogliosis, heterotopic neurons in the white matter, loss of neurons, and the presence of inflammatory cellular infiltrates. Astrocytes exhibit smaller K⁺ conductances and lose gap junction coupling in many animal models as well as in sclerotic hippocampi from temporal lobe epilepsy patients. There is increasing evidence that epilepsy can be prevented or aborted in preclinical animal models of acquired epilepsy by interfering with processes that appear common to multiple acute injury etiologies, for example, in post–status epilepticus models of focal epilepsy by transient treatment with a trkB/PLCγ1 inhibitor, isoflurane, or HMGB1 antibodies and by topical administration of adenosine, in the cortical fluid percussion injury model by focal cooling, and in the albumin posttraumatic epilepsy model by losartan. Preclinical studies further highlight the roles of mTOR1 pathways, JAK-STAT3, IL-1R/TLR4 signaling, and other inflammatory pathways in the genesis or modulation of epilepsy after brain injury. The wealth of commonalities, diversity of molecular targets identified preclinically, and likely multidimensional nature of epileptogenesis argue for a combinatorial strategy in prevention therapy. Going forward, the identification of impending epilepsy biomarkers to allow better patient selection, together with better alignment with multisite preclinical trials in animal models, should guide the clinical testing of new hypotheses for epileptogenesis and its prevention.
... BDNF regulation of 1 and 4 subunit expression via inducible cAMP response element repressor (ICER) and early growth response factor (Egr3) pathways respectively, reviewed in Scharfman and Brooks-Kayal (2014) may also be relevant to drug addiction and could be targeted to therapeutic advantage (see also Alteration in GABA A R function and Conclusion sections). In this regard, the observation that selective early inhibition of STAT3, which mediates BDNF effect upon ICER down-regulation of 1 expression (Grabenstatter et al. 2014b), or increased 1-subunit expression in hippocampus dentate gyrus via a viral-mediated delivery approach (Raol et al. 2006) reduces long-term seizure frequency or the number of animals experiencing spontaneous seizures respectively, in the pilocarpine temporal lobe epilepsy model is intriguing. Secondly, 4 GABA A receptors are known to mediate a sustained form of inhibition known as tonic inhibition, and increased tonic inhibition in the NAcc associates with increased alcohol consumption in two mouse models of increased spontaneous GABA A receptor channel activity (Anstee et al. 2013;Maguire et al. 2014;Rewal et al. 2012; see alpha4-and delta-subunit containing receptors section). ...
Article
GABAA receptors form the major class of inhibitory neurotransmitter receptors in the mammalian brain. This review sets out to summarise the evidence that variations in genes encoding GABAA receptor isoforms are associated with aspects of addictive behaviour in humans, while animal models of addictive behaviour also implicate certain subtypes of GABAA receptor. In addition to outlining the evidence for the involvement of specific subtypes in addiction, we summarise the particular contributions of these isoforms in control over the functioning of brain circuits, especially the mesolimbic system, and make a first attempt to bring together evidence from several fields to understanding potential involvement of GABAA Receptor Subtypes in addictive behaviour. While the weight of the published literature is on alcohol dependency, the underlying principles outlined are relevant across a number of different aspects of addictive behaviour.
... *p , 0.05, **p , 0.01, ***p , 0.001 (one-way ANOVA test). severity along with downregulation of STAT3-regulated genes (42). Our current investigation demonstrates that brain exposure to IL-6 is sufficient to induce seizures in vivo with duration and amplitude depending on the dose of injected IL-6. ...
Article
TGF-β1 is a master cytokine in immune regulation, orchestrating both pro- and anti-inflammatory reactions. Recent studies show that whereas TGF-β1 induces a quiescent microglia phenotype, it plays a pathogenic role in the neurovascular unit and triggers neuronal hyperexcitability and epileptogenesis. In this study, we show that, in primary glial cultures, TGF-β signaling induces rapid upregulation of the cytokine IL-6 in astrocytes, but not in microglia, via enhanced expression, phosphorylation, and nuclear translocation of SMAD2/3. Electrophysiological recordings show that administration of IL-6 increases cortical excitability, culminating in epileptiform discharges in vitro and spontaneous seizures in C57BL/6 mice. Intracellular recordings from layer V pyramidal cells in neocortical slices obtained from IL-6 -: treated mice show that during epileptogenesis, the cells respond to repetitive orthodromic activation with prolonged after-depolarization with no apparent changes in intrinsic membrane properties. Notably, TGF-β1 -: induced IL-6 upregulation occurs in brains of FVB/N but not in brains of C57BL/6 mice. Overall, our data suggest that TGF-β signaling in the brain can cause astrocyte activation whereby IL-6 upregulation results in dysregulation of astrocyte -: neuronal interactions and neuronal hyperexcitability. Whereas IL-6 is epileptogenic in C57BL/6 mice, its upregulation by TGF-β1 is more profound in FVB/N mice characterized as a relatively more susceptible strain to seizure-induced cell death. Copyright © 2015 by The American Association of Immunologists, Inc.
... Reference and ground electrodes (stainless steel screws) were placed bilaterally behind lambda (i.e., over the cerebellum). Dental acrylic was used to secure the electrodes in a plastic connector (Plastics-One, Roanoke, VA) according to standard methods (Zhang et al., 2004;Grabenstatter et al., 2014). Animals were allowed to recover from surgery for 1 week before proceeding with any further experimentation. ...
Article
In this study, we analyzed the impact that spontaneous seizures might have on the plasma membrane expression, composition and function of GABAA receptors (GABAARs). For this, tissue of chronically epileptic rats was collected within 3hours of seizure occurrence (≤3hours group) or at least 24hours after seizure occurrence (≥24hours group). A retrospective analysis of seizure frequency revealed that selecting animals on the bases of seizure proximity also grouped animals in terms of overall seizure burden with a higher seizure burden observed in the ≤3hours group. A biochemical analysis showed that although animals with more frequent/recent seizures (≤3hours group) had similar levels of GABAAR at the plasma membrane they showed deficits in inhibitory neurotransmission. In contrast, tissue obtained from animals experiencing infrequent seizures (≥24hours group) had increased plasma membrane levels of GABAAR and showed no deficit in inhibitory function. Together, our findings offer an initial insight into the molecular changes that might help to explain how alterations in GABAAR function can be associated with differential seizure burden. Our findings also suggest that increased plasma membrane levels of GABAAR might act as a compensatory mechanism to more effectively maintain inhibitory function, repress hyperexcitability and reduce seizure burden. This study is an initial step towards a fuller characterization of the molecular events that trigger alterations in GABAergic neurotransmission during chronic epilepsy. Copyright © 2015. Published by Elsevier Inc.
... Interestingly, inhibition of STAT3 has been implicated in prevention of several other diseases. For example, inhibition of STAT by WP1066 ameliorated the severity of chronic epilepsy [22]. Inhibition of STAT3 significantly attenuated the progressive phenotypes of Alport syndrome in the mouse model [23]. ...
Article
Full-text available
Epithelial-mesenchymal transition (EMT) in peritoneum was induced during peritoneal dialysis (PD), which finally caused progressive fibrosis. However, the underlying mechanisms were not well elucidated. We established advanced glycation end-products (AGEs)-induced EMT model using primary human peritoneal mesothelial cells (HPMCs). The working concentration and time of AGEs were optimized. Then the expression and activation signal transducer and activator of transcription 3 (STAT3), a key factor of EMT in cancer, were detected. The regulation of STAT3 by miRNA was also explored. 50 μg/ml AGEs treatment for 24 h can successfully induce EMT in HPMCs. AGEs treatment upregulated and activated STAT3. miRNA-454, potentially targeting STAT3, was down-regulated in AGEs-treated HPMCs. Overexpression of miRNA-454 prevented AGEs- induced EMT in HPMCs. AGEs induce epithelial to mesenchymal transformation of Human peritoneal mesothelial cells via upregulation of STAT3.
... Kinase signaling, including activation of PI3K-Akt-mTOR, JAK-STAT, and BDNF-TrkB pathways, has been implicated in animal and in vitro models of acquired chronic epilepsies [10][11][12][13][14][15][16][17]. However, kinases that have been found to play a role in epilepsy to date represent only a small percentage of the total kinome, since the human genome includes over 500 kinase genes [18]. ...
Article
Full-text available
Kinase signaling plays an important role in acquired epilepsy, but only a small percentage of the total kinome has been investigated in this context. A major roadblock that prevents the systematic investigation of the contributions of kinase signaling networks is the slow speed of experiments designed to test the chronic effects of target inhibition in epilepsy models. We developed a novel in vitro screening platform based on microwire recordings from an organotypic hippocampal culture model of acquired epilepsy. This platform enables the direct, parallel determination of the effects of compounds on spontaneous epileptiform activity. The platform also enables repeated recordings from the same culture over two-week long experiments. We screened 45 kinase inhibitors and quantified their effects on seizure duration, the frequency of paroxysmal activity, and electrographic load. We identified several inhibitors with previously unknown antiepileptic properties. We also used kinase inhibition profile cross-referencing to identify kinases that are inhibited by seizure-suppressing compounds, but not by compounds that had no effect on seizures.
... In the present study, a pilocarpine-induced seizure model was selected, which highly resembles the morphological and synaptic characteristics of TLE in humans. Rats injected with pilocarpine endure a period of status epilepticus followed by a chronic indefinite period of spontaneous recurrent seizures (21). ...
Article
Full-text available
Previous studies have indicated that the adenosine triphosphate‑sensitive homomeric P2X7 receptor (P2X7R) plays an important role and exhibits therapeutic potential in a number of brain disorders, including temporal lobe epilepsy (TLE). The aim of the present study was to assess the expression of P2X7R, glutamate (GLU) and glial fibrillary acidic protein (GFAP) in the temporal neocortex and hippocampus of rats with lithium‑pilocarpine‑induced epilepsy as well as in patients with intractable TLE. The results demonstrated that the levels of P2X7R, GLU and GFAP were significantly upregulated in rats with spontaneous recurrent seizures, whereas they were reduced in rats that were treated with brilliant blue G (BBG), a P2X7R antagonist. To the best of our knowledge, the present study is also the first to demonstrate that P2X7R expression was elevated in patients with intractable TLE. These findings suggest that P2X7R plays a key role in the development of TLE and that BBG treatment may be a promising therapeutic strategy for TLE.
... Finally, the PET experiment detected signal from a benzodiazepine antagonist ([11C]flumazenil) while the autoradiogra phy experiment used a b enzodiaz epine ([3H]flunitrazepam). GABA A Rs composed of different subunits/subunit isoforms have unique physiological properties as well as different affinities for benzodiazepines and different relative affinities for benzodiazepine agonists and antagonists [177,[197][198][199]. Alterations in GABA A R subunit/ subunit isoform composition have been identified in key regions of epilepsy networks and have resulted in modified GABA A transmission [190,[200][201][202][203][204]. ...
Article
Full-text available
Tremor is the most common movement disorder; however, we are just beginning to understand the brain circuitry that generates tremor. Various neuroimaging, neuropathological, and physiological studies in human tremor disorders have been performed to further our knowledge of tremor. But, the causal relationship between these observations and tremor is usually difficult to establish and detailed mechanisms are not sufficiently studied. To overcome these obstacles, animal models can provide an important means to look into human tremor disorders. In this manuscript, we will discuss the use of different species of animals (mice, rats, fruit flies, pigs, and monkeys) to model human tremor disorders. Several ways to manipulate the brain circuitry and physiology in these animal models (pharmacology, genetics, and lesioning) will also be discussed. Finally, we will discuss how these animal models can help us to gain knowledge of the pathophysiology of human tremor disorders, which could serve as a platform towards developing novel therapies for tremor.
... Genetic predispositions for developing seizures can for example arise as a result of channelopathies, which are each associated with specific seizure types and probabilities of having certain symptoms (Chang and Lowenstein, 2003;Glasscock et al., 2007). Other examples include mutations in transcriptional regulators such as JAK-STAT (Grabenstatter et al., 2014), proteins involved in cell growth such as mTOR (Way et al., 2012), or expansions in noncoding regions (Ishiura et al., 2018). On the other hand, acquired epilepsy can arise for many different reasons including: traumatic brain injury, infection, cancer, cerebrovascular disorder, autoimmune disorder, and developmental malformation (Berkovic et al., 2006). ...
Article
Full-text available
Epilepsy is a major neurological disorder characterized by repeated seizures afflicting 1% of the global population. The emergence of seizures is associated with several comorbidities and severely decreases the quality of life of patients. Unfortunately, around 30% of patients do not respond to first-line treatment using anti-seizure drugs (ASDs). Furthermore, it is still unclear how seizures arise in the healthy brain. Therefore, it is critical to have well developed models where a causal understanding of epilepsy can be investigated. While the development of seizures has been studied in several animal models, using chemical or electrical induction, deciphering the results of such studies has been difficult due to the uncertainty of the cell population being targeted as well as potential confounds such as brain damage from the procedure itself. Here we describe novel approaches using combinations of optical and genetic methods for studying epileptogenesis. These approaches can circumvent some shortcomings associated with the classical animal models and may thus increase the likelihood of developing new treatment options.
... What's more, we have found that Foxp1 is the target gene of miR-183, and reduced miR-183 could elevate the expression of Foxp1, which is a new finding that has not been revealed in other studies. In addition, our research has illustrated that the Jak/Stat signaling pathway was activated in EP, and a similar result has been clarified in pilocarpine-induced status epilepticus by Grabenstatter et al. [27]. Another important result of this research unraveled that inhibited miR-183 could alleviate hippocampal neuron injury in EP by promoting the expression of Foxp1. ...
Article
Recently, the impacts of microRNAs (miRNAs) have been identified in epilepsy (EP), this study was designed to assess the role of miR-183 in hippocampal neuron injury in EP. Rat EP models were established by injected with lithium-pilocarpine. The pathological observation of rats’ hippocampus sections was conducted. Expression of miR-183, Foxp1, Jak1, Stat1, and Stat3 in rats’ hippocampal tissues was determined by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis. The proliferation ability and the apoptosis of the rats’ neurons were measured. Furthermore, the target relation between miR-183 and Foxp1 was determined by bioinformatics analysis and dual-luciferase gene reporter assay. The levels of miR-183, Jak1, Stat1, and Stat3 were elevated, and the expression of Foxp1 was declined in EP rats’ hippocampal tissues. Inhibited miR-183 could up-regulate Foxp1, inhibited miR-183 together with up-regulated Foxp1 could repress hippocampal neuron injury, promote neuron proliferation, suppress neuron apoptosis, and inactivate the Jak/Stat signaling pathway, resulting in an attenuation of EP progression. Moreover, down-regulated Foxp1 could reverse the attenuation of EP progression which was contributed by inhibited miR-183. Our study implies that inhibited miR-183 could up-regulate Foxp1, resulting in an inactivation of the Jak/Stat signaling pathway and promotion of neuron proliferation, as well as inhibition of apoptosis of hippocampal neurons in EP rats, by which the hippocampal neuron injury and EP progression could be repressed.
... For up-regulated genes, STAT3, a nuclear factor associated with the JAK/STAT pathway, is the principal driver. This observation aligns with reports arguing that activation of the JAK/STAT pathway occurs in both pilocarpine and kainic acid SE models [44][45][46] . Interestingly, EZH2 was also found to be a significant driver of up-regulated genes (Figure 2A). ...
Preprint
Full-text available
Complex neurological conditions can give rise to large scale transcriptomic changes that drive disease progression. It is likely that alterations in one or a few transcription factors or cofactors underlie these transcriptomic alterations. Identifying the driving transcription factors/cofactors is a non-trivial problem and a limiting step in the understanding of neurological disorders. Epilepsy has a prevalence of 1% and is the fourth most common neurological disorder. While a number of anti-seizure drugs exist to treat seizures symptomatically, none is curative or preventive. This reflects a lack of understanding of disease progression. We used a novel systems approach to mine transcriptome profiles of rodent and human epileptic brain samples to identify regulators of transcriptional networks in the epileptic brain. We find that Enhancer of Zeste Homolog 2 (EZH2) regulates differentially expressed genes in epilepsy across multiple rodent models of acquired epilepsy. EZH2 undergoes a prolonged upregulation in the epileptic brain. A transient inhibition of EZH2 immediately after seizure induction robustly increases spontaneous seizure burden weeks later. Thus, EZH2 upregulation is a protective response mounted after a seizure. These findings are the first to characterize a role for EZH2 in opposing epileptogenesis and debut a bioinformatic approach to identify nuclear drivers of complex transcriptional changes in disease. Author Summary Epilepsy is the fourth most common neurological disorder and has been described since the time of Hippocrates. Despite this, no treatments exist to stop epilepsy progression. This is fundamentally due to the complex nature of the disease. Epilepsy is associated with hundreds if not thousands of gene expression changes in the brain that are likely driven by a few key master regulators called transcription factors and cofactors. Finding the aberrantly acting factors is a complex problem that currently lacks a satisfactory solution. We used a novel datamining tool to define key master regulators of gene expression changes across multiple epilepsy models and patient samples. We find that a nuclear enzyme, EZH2, regulates a large number of genes in the rodent and patient epileptic brain and that it’s function is protective. Thus, inhibiting EZH2 greatly exacerbates seizure burden. This is the first report of a novel datamining tool to define drivers of large-scale gene changes and is also the first report of EZH2 induction as an endogenous protective response in the epilepsy.
... For up-regulated genes, STAT3, a nuclear factor associated with the JAK/STAT pathway, is the principal driver. This observation aligns with reports arguing that activation of the JAK/STAT pathway occurs in both pilocarpine and kainic acid SE models [44][45][46]. Interestingly, EZH2 was also found to be a significant driver of up-regulated genes (Fig 2A). ...
Article
Full-text available
Complex neurological conditions can give rise to large scale transcriptomic changes that drive disease progression. It is likely that alterations in one or a few transcription factors or cofactors underlie these transcriptomic alterations. Identifying the driving transcription factors/cofactors is a non-trivial problem and a limiting step in the understanding of neurological disorders. Epilepsy has a prevalence of 1% and is the fourth most common neurological disorder. While a number of anti-seizure drugs exist to treat seizures symptomatically, none is curative or preventive. This reflects a lack of understanding of disease progression. We used a novel systems approach to mine transcriptome profiles of rodent and human epileptic brain samples to identify regulators of transcriptional networks in the epileptic brain. We find that Enhancer of Zeste Homolog 2 (EZH2) regulates differentially expressed genes in epilepsy across multiple rodent models of acquired epilepsy. EZH2 undergoes a prolonged upregulation in the epileptic brain. A transient inhibition of EZH2 immediately after status epilepticus (SE) robustly increases spontaneous seizure burden weeks later. This suggests that EZH2 upregulation is a protective. These findings are the first to characterize a role for EZH2 in opposing epileptogenesis and debut a bioinformatic approach to identify nuclear drivers of complex transcriptional changes in disease.
... In chronic epilepsy, kinase signaling comprising of activated JAK-STAT, BDNF-TrkB, and PI3K-Akt-mTOR pathways have been demonstrated in animal and in vitro models [107][108][109][110][111][112][113][114]. Till date, a small percentage of PP2 Prevent albuminuria, glomerular matrix protein accumulation, GBM thickening, and podocyte depletion [90] PP2 Decrease levels of blood urea nitrogen and serum creatinine, triglyceride, and urine albumin [91] SKI-606 Reduce renal epithelial cell matrix adhesion, proliferation, and cyst formation [92] SKI-606 Ameliorate renal cyst formation and biliary ductal abnormalities [93] Col4, collagen 4; TACE, tumor necrosis factor-converting enzyme; EGFR, epidermal growth factor receptor; MAPK, mitogen-activated protein kinase; GBM, glomerular base membrane kinases have been found to play a major role in epilepsy [115]. ...
Article
Full-text available
Background Src kinase, a nonreceptor protein-tyrosine kinase is composed of 11 members (in human) and is involved in a wide variety of essential functions required to sustain cellular homeostasis and survival. Main body of the abstract Deregulated activity of Src family kinase is related to malignant transformation. In 2001, Food and Drug Administration approved imatinib for the treatment of chronic myeloid leukemia followed by approval of various other inhibitors from this category as effective therapeutics for cancer patients. In the past decade, Src family kinase has been investigated for the treatment of diverse pathologies in addition to cancer. In this regard, we provide a systematic evaluation of Src kinase regarding its mechanistic role in cancer and other diseases. Here we comment on preclinical and clinical success of Src kinase inhibitors in cancer followed by diabetes, hypertension, tuberculosis, and inflammation. Short conclusion Studies focusing on the diversified role of Src kinase as potential therapeutical target for the development of medicinally active agents might produce significant advances in the management of not only various types of cancer but also other diseases which are in demand for potent and safe therapeutics.
... Similarly, Zhang et al. (2019) found that STAT3 was overexpressed in 169 children suffering from epilepsy, suggesting that it is associated with the risk of epilepsy and drug resistance to epilepsy (Li et al., 2020). By inhibiting STAT3 gene transcription, the frequency of seizures can be reduced (Grabenstatter et al., 2014). ...
Article
Full-text available
Epilepsy is a chronic brain dysfunction induced by an abnormal neuronal discharge that is caused by complicated psychopathologies. Recently, accumulating studies have revealed a close relationship between inflammation and epilepsy. Specifically, microglia and astrocytes are important inflammatory cells in the central nervous system (CNS) that have been proven to be related to the pathogenesis and development of epilepsy. Additionally, interleukin 4 (IL-4) is an anti-inflammatory factor that can regulate microglia and astrocytes in many aspects. This review article focuses on the regulatory role of IL-4 in the pathological changes of glial cells related to epilepsy. We additionally propose that IL-4 may play a protective role in epileptogenesis and suggest that IL-4 may be a novel therapeutic target for the treatment of epilepsy.
... Tlr2, Stat3 and Ptgs2 are well-known mediators of neuroinflammation and are potential antiseizure or antiepilepsy targets. 21,[25][26][27] CD44 is an extracellular adhesion molecule expressed by glial cells and neurons. It regulates neurite outgrowth, leukocyte homing, synaptic transmission, and BBB integrity. ...
Article
Full-text available
Aims To identify transcriptome signatures underlying epileptogenesis in temporal lobe epilepsy (TLE). Methods Robust rank aggregation analysis was used to integrate multiple microarrays in rodent models of TLE and determine differentially expressed genes (DEGs) in acute, latent, and chronic stages. Functional annotation and protein‐protein interaction analysis were performed to explore the potential functions of the DEGs and identify hub genes with the highest intramodular connectivity. The association between hub genes and hippocampal sclerosis/seizure frequency was analyzed using publicly available RNA‐sequencing datasets from TLE patients. We subsequently established a pilocarpine‐induced status epilepticus (SE) model in rats and validated mRNA expression of hub genes by quantitative reverse transcription PCR (qRT‐PCR). Results The DEGs in the acute, latent, and chronic phases of TLE in animal models were prominently enriched in inflammatory response. Hub genes identified in the acute phase mainly participated in biological processes including inflammation, blood‐brain barrier damage, and cell adhesion. The hub genes in the latent phase were related to microglia/macrophage activation (Emr1 and Aif1) and phagocytosis (Cd68, Tyrobp, and Lyz). In the chronic phase, the hub genes were associated with activation of complements and microglia/macrophages. We further found that some hub genes identified in human TLE, such as Tlr2, Lgals3, and Stat3, were positively correlated with seizure frequency. Other hub genes, including Lgals3 and Serpine1, were associated with hippocampus sclerosis. qRT‐PCR analysis confirmed that the mRNA levels of hub genes in rat hippocampus were significantly up‐regulated after SE induction. Conclusions Our integrated analysis identified hub genes in different stages of epilepsy. The functional annotations suggest that the activation and phagocytic activities of microglia/macrophages may play critical roles in epileptogenesis of TLE.
... HDAC3 is also able to deacetylate and regulate the dephosphorylation at ser727 of STAT3, thus, repressing its activity [28,29]. Studies conducted using experimental models as well as human samples have reported that there is an increase in the levels of both STAT1 and STAT3 in the hippocampus following seizures [30][31][32]. Since STATs are key signaling mediators whose expression is induced by interleukins and interferons, the regulation of their subcellular localization by HDAC3 can provide an insight into the mechanism of epileptogenesis. ...
Article
Full-text available
Introduction: Epilepsy is a network-level neurological disorder characterized by unprovoked recurrent seizures and associated comorbidities. Aberrant activity and localization of histone deacetylases (HDACs) have been reported in epilepsy and HDAC inhibitors (HDACi) have been used for therapeutic purposes. Several non-histone targets of HDACs have been recognized whose reversible acetylation can modulate protein functions and can contribute to disease pathology. Areas covered: This review provides an overview of HDACs in epilepsy and reflects its action on non-histone substrates involved in the pathogenesis of epilepsy and explores the effectiveness of HDACi as anti-epileptic drugs (AEDs). It also covers the efforts undertaken to target the interaction of HDACs with their substrates. We have further discussed non-deacetylase activity possessed by specific HDACs that might be essential in unraveling the molecular mechanism underlying the disease. For this purpose, relevant literature from 1996 to 2020 was derived from PubMed. Expert opinion: The interaction of HDACs and their non-histone substrates can serve as a promising therapeutic target for epilepsy. Pan-HDACi offers limited benefits to the epileptic patients. Thus, identification of novel targets of HDACs contributing to the disease and designing inhibitors targeting these complexes would be more effective and holds a greater potential as an anti-epileptogenic therapy. ARTICLE HISTORY
Article
Full-text available
Brain-derived neurotrophic factor (BDNF) levels are elevated after status epilepticus (SE), leading to activation of multiple signaling pathways, including the janus kinase/signal transducer and activator of transcription pathway that mediates a decrease in GABAA receptor α1 subunits in the hippocampus (Lund et al., 2008). While BDNF can signal via its pro or mature form, the relative contribution of these forms to signaling after SE is not fully known. In the current study, we investigate changes in proBDNF levels acutely after SE in C57BL/6J mice. In contrast to previous reports (Unsain et al., 2008; Volosin et al., 2008; VonDran et al., 2014), our studies found that levels of proBDNF in the hippocampus are markedly elevated as early as 3 h after SE onset and remain elevated for 7 d. Immunohistochemistry studies indicate that seizure-induced BDNF localizes to all hippocampal subfields, predominantly in principal neurons and also in astrocytes. Analysis of the proteolytic machinery that cleaves proBDNF to produce mature BDNF demonstrates that acutely after SE there is a decrease in tissue plasminogen activator and an increase in plasminogen activator inhibitor-1 (PAI-1), an inhibitor of extracellular and intracellular cleavage, which normalizes over the first week after SE. In vitro treatment of hippocampal slices from animals 24 h after SE with a PAI-1 inhibitor reduces proBDNF levels. These findings suggest that rapid proBDNF increases following SE are due in part to reduced cleavage, and that proBDNF may be part of the initial neurotrophin response driving intracellular signaling during the acute phase of epileptogenesis.
Article
Full-text available
Colony Stimulating Factor 1 Receptor (CSF1R) is a potential target for anti-epileptic drugs. However, inhibition of CSF1R is not well tolerated by patients, thereby prompting the need for alternative targets. To develop a framework for identification of such alternatives, we here develop a mathematical model of a pro-inflammatory gene regulatory network (GRN) involved in epilepsy and centered around CSF1R. This GRN comprises validated transcriptional and post-transcriptional regulations involving STAT1, STAT3, NFκB, IL6R, CSF3R, IRF8, PU1, C/EBPα, TNFR1, CSF1 and CSF1R. The model was calibrated on mRNA levels of all GRN components in lipopolysaccharide (LPS)-treated mouse microglial BV-2 cells, and allowed to predict that STAT1 and STAT3 have the strongest impact on the expression of the other GRN components. Microglial BV-2 cells were selected because, the modules from which the GRN was deduced are enriched for microglial marker genes. The function of STAT1 and STAT3 in the GRN was experimentally validated in BV-2 cells. Further, in silico analysis of the GRN dynamics predicted that a pro-inflammatory stimulus can induce irreversible bistability whereby the expression level of GRN components occurs as two distinct states. The irreversibility of the switch may enforce the need for chronic inhibition of the CSF1R GRN in order to achieve therapeutic benefit. The cell-to-cell heterogeneity driven by the bistability may cause variable therapeutic response. In conclusion, our modeling approach uncovered a GRN controlling CSF1R that is predominantly regulated by STAT1 and STAT3. Irreversible inflammation-induced bistability and cell-to-cell heterogeneity of the GRN provide a theoretical foundation to the need for chronic GRN control and the limited potential for disease modification via inhibition of CSF1R.
Article
Complex circuitry with feed-forward and feed-back systems regulate neuronal activity throughout the brain. Cell biological, electrical, and neurotransmitter systems enable neural networks to process and drive the entire spectrum of cognitive, behavioral, and motor functions. Simultaneous orchestration of distinct cells and interconnected neural circuits relies on hundreds, if not thousands, of unique molecular interactions. Even single molecule dysfunctions can be disrupting to neural circuit activity, leading to neurological pathology. Here, we sample our current understanding of how molecular aberrations lead to disruptions in networks using three neurological pathologies as exemplars: epilepsy, traumatic brain injury (TBI), and Alzheimer's disease (AD). Epilepsy provides a window into how total destabilization of network balance can occur. TBI is an abrupt physical disruption that manifests in both acute and chronic neurological deficits. Last, in AD progressive cell loss leads to devastating cognitive consequences. Interestingly, all three of these neurological diseases are interrelated. The goal of this review, therefore, is to identify molecular changes that may lead to network dysfunction, elaborate on how altered network activity and circuit structure can contribute to neurological disease, and suggest common threads that may lie at the heart of molecular circuit dysfunction. © The Author(s) 2015.
Article
Epileptogenesis is most commonly associated with neurodegeneration and a bioenergetic defect attributing to the fact that mitochondrial dysfunction plays a key precursor for neuronal death. Mitochondria are the essential organelle of neuronal cells necessary for certain neurophysiological processes like neuronal action potential activity and synaptic transmission. The mitochondrial dysfunction disrupts calcium homeostasis leading to inhibitory interneuron dysfunction and increasing the excitatory postsynaptic potential. In epilepsy, the prolonged repetitive neuronal activity increases the excessive demand for energy and acidosis in the brain further increasing the intracellular calcium causing neuronal death. Similarly, the mitochondrial damage also leads to the decline of energy by dysfunction of the electron transport chain and abnormal production of the ROS triggering the apoptotic neuronal death. Thus, the elevated level of cytosolic calcium causes the mitochondria DNA damage coinciding with mtROS and releasing the cytochrome c binding to Apaf protein further initiating the apoptosis resulting in epileptic encephalopathies. The various genetic and mRNA studies of epilepsy have explored the various pathogenic mutations of genes affecting the mitochondria functioning further initiating the neuronal excitotoxicity. Based on the results of previous studies, the recent therapeutic approaches are targeting basic mitochondrial processes, such as energy metabolism or free-radical generation, or specific interactions of disease-related proteins with mitochondria and hold great promise to attenuate epileptogenesis. Therefore, the current review emphasizes the emerging insights to uncover the relation between mitochondrial dysfunction and ROS generation contributing to mechanisms underlying epileptic seizures.
Article
Full-text available
Multiple Sclerosis (MS) is a severe brain and spinal cord condition with a diverse autoimmune response and a wide variety of demyelination symptoms that primarily affect young adults. The primary reason for this disease is inflammation of white and grey matter caused by increased production of proinflammatory cytokines, which further damages the progenitor oligodendrocytes and appears to induce hypertrophy of the astrocytes and gliosis. Overexpression of the JAK/STAT signaling pathway contributes directly to physiological and pathological results in motor neuron diseases. Cytokines such as IL-17, IL-6, IL-12, TNF-α, and INF-ϒ use JAK/STAT signaling to trigger self-reactive CD4+ T-cells differentiate them into Th1 phenotypes that over-activate immune reactions in the brain. Similarly, PPARγ plays a critical role in regulating the immune response by providing an anti-inflammatory effect by inhibiting macrophage and cytokine production activation. PPARγ also mediates the intrinsic molecular process of the T-cell, which selectively regulates the differentiation of Th17. Various studies indicate the neuroprotective function of PPARγ agonists by attenuating the JAK/STAT mediated activation of glial cells, inhibiting interleukin, and the differentiation of Th1 cells. Therefore, to maintain the brain's immune system, both PPARγ,and JAK/STAT oppositely regulate each other. Dysregulation in JAK/STAT and PPARγ signaling contributes to several physiological changes leading to neurological disorders, including MS. Based on the above view; we summarized the combined role of JAK/STAT-PPARγsignaling in MS and explored potential therapeutic strategies for disease improvement by the use of pathway modulators.
Article
In this study, we used the pilocarpine model of epilepsy to evaluate the involvement of calpain dysregulation on epileptogenesis. Detection of spectrin breakdown products (SBDPs, a hallmark of calpain activation) after induction of pilocarpine-induced status epilepticus (SE) and before appearance of spontaneous seizure suggested the existence of sustained calpain activation during epileptogenesis. Acute treatment with the cell permeable inhibitor of calpain, MDL-28170, resulted in a partial but significant reduction on seizure burden. The reduction on seizure burden was associated with a limited reduction on the generation of SBDPs but was correlated with a reduction in astrocytosis, microglia activation and cell sprouting. Together, these observations provide evidence for the role of calpain in epileptogenesis. In addition, provide proof-of-principle for the use of calpain inhibitors as a novel strategy to prevent epileptic seizures and its associated pathologies.
Article
Traumatic brain injury (TBI) greatly increases the risk of medically intractable epilepsy. Several models of TBI have been developed to investigate the relationship between TBI and posttraumatic epileptogenesis. Because the incident that precipitates development of epilepsy is known, studying mechanisms of epileptogenesis, identifying biomarkers to predict PTE, and developing treatments to prevent epilepsy after TBI are attainable research goals.
Article
Patients with TLE are prone to tolerance to antiepileptic drugs. Based on the perspective of molecular targets for drug resistance, it is necessary to explore effective drug resistant genes and signaling pathways for the treatment of TLE. We performed gene expression profiles in hippocampus of patients with drug-resistant TLE and identified ROCK2 as one of the 20 most significantly increased genes in hippocampus. In vitro and in vivo experiments were performed to identify the potential role of ROCK2 in epileptogenesis. In addition, the activity of Stat3 pathway was tested in rat hippocampal tissues and primary cultured astrocytes. The expression levels of ROCK2 in the hippocampus of TLE patients were significantly increased compared with the control group, which was due to the hypomethylation of ROCK2 promoter. Fasudil, a specific Rho-kinase inhibitor, alleviated epileptic seizures in the pilocarpine rat model of TLE. Furthermore, ROCK2 activated the Stat3 pathway in pilocarpine-treated epilepsy rats, and the spearman correlation method confirmed that ROCK2 is associated with Stat3 activation in TLE patients. In addition, ROCK2 was predominantly expressed in astrocytes during epileptogenesis, and induced epileptogenesis by activating astrocyte cell cycle progression via Stat3 pathway. The overexpressed ROCK2 plays an important role in the pathogenesis of drug-resistant epilepsy. ROCK2 accelerates astrocytes cell cycle progression via the activation of Stat3 pathway likely provides the key to explaining the process of epileptogenesis.
Article
C-X-C motif chemokine receptor 2 (CXCR2) is one of the most well characterized chemokine receptors and is a potential target for treating brain pathologies involving inflammatory processes, including epilepsy. However, the role of CXCR2 in epilepsy has not been investigated, and whether CXCR2 modulates seizure activity in temporal lobe epilepsy (TLE) remains unknown. In this study, we aimed to determine the potential role of CXCR2 in intractable TLE patients and in pilocarpine-induced epileptic mice. Here, through Western blotting and semi-quantitative immunohistochemistry, we detected that CXCR2 protein expression was up-regulated (by nearly 50%) in the temporal neocortex of TLE patients and in the hippocampus and adjacent temporal cortex of pilocarpine mice model. Double-label immunofluorescence and immunohistochemical analysis indicated that CXCR2 was expressed in neurons. To investigate the effect of the CXCR2 selective antagonist SB225002 on seizure activity, SB225002 was i.p. administered during the latency window of spontaneous recurrent seizures (SRSs). This treatment increased (by nearly 40%) the latency of SRSs and reduced (by nearly 50%) the frequency of SRSs during the chronic period of epilepsy. This study suggests that CXCR2 plays a critical role in modifying epileptic seizure activity and that CXCR2 blockade could be a potential molecular therapeutic target for epilepsy.
Article
Full-text available
Elevated levels of chemokine C-C motif ligand 2 (CCL2) and its receptor CCR2 have been reported in patients with temporal lobe epilepsy and in experimental seizures. However, the functional significance and molecular mechanism underlying CCL2-CCR2 signaling in epileptic brain remains largely unknown. In this study, we found that the upregulated CCL2 was mainly expressed in hippocampal neurons and activated microglia from mice 1 d after kainic acid (KA)-induced seizures. Taking advantage ofCX3CR1 GFP /+:CCR2 RFP /+double-transgenic mice, we demonstrated that CCL2-CCR2 signaling has a role in resident microglial activation and blood-derived monocyte infiltration. Moreover, seizure-induced degeneration of neurons in the hippocampal CA3 region was attenuated in mice lacking CCL2 or CCR2. We further showed that CCR2 activation induced STAT3 (signal transducer and activator of transcription 3) phosphorylation and IL-1β production, which are critical for promoting neuronal cell death after status epilepticus. Consistently, pharmacological inhibition of STAT3 by WP1066 reduced seizure-induced IL-1β production and subsequent neuronal death. Two weeks after KA-induced seizures, CCR2 deficiency not only reduced neuronal loss, but also attenuated seizure-induced behavioral impairments, including anxiety, memory decline, and recurrent seizure severity. Together, we demonstrated that CCL2-CCR2 signaling contributes to neurodegeneration via STAT3 activation and IL-1β production after status epilepticus, providing potential therapeutic targets for the treatment of epilepsy.SIGNIFICANCE STATEMENTEpilepsy is a global concern and epileptic seizures occur in many neurological conditions. Neuroinflammation associated with microglial activation and monocyte infiltration are characteristic of epileptic brains. However, molecular mechanisms underlying neuroinflammation in neuronal death following epilepsy remain to be elucidated. Here we demonstrate that CCL2-CCR2 signaling is required for monocyte infiltration, which in turn contributes to kainic acid (KA)-induced neuronal cell death. The downstream of CCR2 activation involves STAT3 (signal transducer and activator of transcription 3) phosphorylation and IL-1β production. Two weeks after KA-induced seizures, CCR2 deficiency not only reduced neuronal loss, but also attenuated seizure-induced behavioral impairments, including anxiety, memory decline, and recurrent seizure severity. The current study provides a novel insight on the function and mechanisms of CCL2-CCR2 signaling in KA-induced neurodegeneration and behavioral deficits.
Article
Introduction: Epilepsy is a network-level neurological disorder characterized by unprovoked recurrent seizures and associated comorbidities. Aberrant activity and localization of histone deacetylases (HDACs) have been reported in epilepsy and HDAC inhibitors (HDACi) have been used for therapeutic purposes. Several non-histone targets of HDACs have been recognized whose reversible acetylation can modulate protein functions and can contribute to disease pathology. Areas covered: This review provides an overview of HDACs in epilepsy and reflects its action on non-histone substrates involved in the pathogenesis of epilepsy and explores the effectiveness of HDACi as anti-epileptic drugs (AEDs). It also covers the efforts undertaken to target the interaction of HDACs with their substrates. We have further discussed non-deacetylase activity possessed by specific HDACs that might be essential in unraveling the molecular mechanism underlying the disease. For this purpose, relevant literature from 1996 to 2020 was derived from PubMed. Expert opinion: The interaction of HDACs and their non-histone substrates can serve as a promising therapeutic target for epilepsy. Pan-HDACi offers limited benefits to the epileptic patients. Thus, identification of novel targets of HDACs contributing to the disease and designing inhibitors targeting these complexes would be more effective and holds a greater potential as an anti-epileptogenic therapy.
Article
Although over 25 antiepileptic drugs (AEDs) have become currently available for clinical use, the incidence of epilepsy worldwide and the proportions of drug-resistant epilepsy among them are not significantly reduced during the past decades. Traditional screens for AEDs have been mainly focused on their anti-ictogenic roles, and their efficacies primarily depend on suppressing neuronal excitability or enhancing inhibitory neuronal activity, almost without the influence on the epileptogenesis or with inconsistent results from different studies. Epileptogenesis refers to the pathological process of a brain from its normal status to the alterations with the continuous prone of unprovoked spontaneous seizures after brain insults, such as stroke, traumatic brain injury, CNS infectious and autoimmune disorders, and even some specific inherited conditions. Recently growing experimental and clinical studies have discovered the underlying mechanisms for epileptogenesis, which are multiaspect and multistep. These findings provide us a number of interesting sites for antiepileptogenic drugs (AEGDs). AEGDs have been evidenced as significantly roles of postponing or completely blocking the development of epilepsy in experimental models. The present review will introduce potential novel candidate drug-targets for AEGDs based on the published studies.
Article
Morin is a bioactive flavonoid with prominent neuroprotective potentials, however, its impact on epilepsy-provoked cognitive dysregulations has not been revealed. Hence, the present investigation aims to divulge the potential anticonvulsant/neuroprotective effects of morin in rats using a pentylenetetrazole (PTZ)-induced kindling model with an emphasis on the possible signaling trajectories involved. Kindling was induced using a sub-convulsive dose of PTZ (35 mg/kg, i.p.), once every other day for 25 days (12 injections). The expression of targeted biomarkers and molecular signals were examined in hippocampal tissues by ELISA, Western blotting, immunohistochemistry, and histopathology. Contrary to PTZ effects, administration of morin (10 mg/kg, i.p., from day 15 of PTZ injection to the end of the experiment) significantly reduced the severity of seizures coupled with a delay in kindling acquisition. It also preserved hippocampal neurons, and diminished astrogliosis to counteract cognitive deficits, exhibited by the enhanced performance in MWM and PA tests. These favorable impacts of morin were mediated via the abrogation of the PTZ-induced necroptotic changes and mitochondrial fragmentation proven by the suppression of p-RIPK-1/p-RIPK-3/p-MLKL and PGAM5/Drp-1 cues alongside the enhancement of caspase-8. Besides, morin inhibited the inflammatory cascade documented by the attenuation of the pro-convulsant receptor/cytokines TNFR-1, TNF-α, I L-1β, and IL-6 and the marked reduction of hippocampal IL-6/p-JAK2/p-STAT3/GFAP cue. In tandem, morin signified its anti-oxidant capacity by lowering the hippocampal contents of MDA, NOX-1, and Keap-1 with the restoration of the impaired Nrf-2/HO-1 pathway. Together, these versatile neuro-modulatory effects highlight the promising role of morin in the management of epilepsy.
Article
Full-text available
Temporal lobe epilepsy represents the largest group of patients with treatment resistant/medically intractable epilepsy undergoing epilepsy surgery. The underpinnings of common forms of TLE in many instances begin in early life with the occurrence of an initial precipitating event. The first epileptic seizure often occurs after a variable latency period following this event. The precise natural history and progression following the first seizure to the development of TLE, its subsequent resolution through spontaneous remission or the development of treatment resistant epilepsy remain poorly understood. Our present understanding of the role played by these initial events, the subsequent latency to development of temporal lobe epilepsy, and the emergence of treatment resistance remains incomplete. A critical analysis of published data suggest that TLE is a heterogeneous condition, where the age of onset, presence or absence of a lesion on neuroimaging, the initial precipitating event, association with febrile seizures, febrile status epilepticus, and neurotropic viral infections influence the natural history and outcome. The pathways and processes through which these variables coalesce into a framework will provide the basis for an understanding of the natural history of TLE. The questions raised need to be addressed in future prospective and longitudinal observational studies.
Article
Full-text available
Cell cycle activation (CCA) is one of the principal secondary injury mechanisms following brain trauma, and it leads to neuronal cell death, microglial activation, and neurological dysfunction. Cyclin D1 (CD1) is a key modulator of CCA and is upregulated in neurons and microglia following traumatic brain injury (TBI). In this study we subjected CD1-wild-type (CD1(+/+)) and knockout (CD1(-/-)) mice to controlled cortical impact (CCI) injury to evaluate the role of CD1 in post-traumatic neurodegeneration and neuroinflammation. As early as 24 h post-injury, CD1(+/+) mice showed markers of CCA in the injured hemisphere, including increased CD1, E2F1, and proliferating cell nuclear antigen (PCNA), as well as increased Fluoro-Jade B staining, indicating neuronal degeneration. Progressive neuronal loss in the hippocampus was observed through 21 days post-injury in these mice, which correlated with a decline in cognitive function. Microglial activation in the injured hemisphere peaked at 7 days post-injury, with sustained increases at 21 days. In contrast, CD1(-/-) mice showed reduced CCA and neurodegeneration at 24 h, as well as improved cognitive function, attenuated hippocampal neuronal cell loss, decreased lesion volume, and cortical microglial activation at 21 days post-injury. These findings indicate that CD1-dependent CCA plays a significant role in the neuroinflammation, progressive neurodegeneration, and related neurological dysfunction resulting from TBI. Our results further substantiate the proposed role of CCA in post-traumatic secondary injury, and suggest that inhibition of CD1 may be a key therapeutic target for TBI.
Article
Full-text available
Introduction: Signal transducer and activator of transcription 3 (STAT3) controls a key signaling pathway in the development of many malignant diseases. Several genetic studies have proven its central role in the regulation of apoptosis, proliferation, angiogenesis and immune responses making it an attractive target for cancer therapy. Areas covered: This article addresses the role of STAT3 in immune response modulation and highlights the contribution of STAT3 in inflammation-mediated tumorigenesis. We also review the rationale to use novel STAT3 inhibitors and list some of these inhibitors such as STA-21, IS3 295, S3I- M2001 and small molecule JAK2 inhibitors AZD1480 and AZ960 that have been found to be efficient against tumors. We summarize the efforts that have been made so far in identifying promising compounds and mention the barriers that need to be overcome for successful application of STAT3 inhibitors in clinics. Expert opinion: STAT3 is an important target in tumor biology based on its frequent activation in various tumors and its pleiotropic effects on different cell types. Screening large libraries of logically synthesized small molecule inhibitors is one way to rapidly generate many potential molecules, which can then be tested in different biologically relevant models. The stage is, therefore, set for the identification and development of novel STAT3 inhibitors that will, in the very near future, enter the clinical realm.
Article
Full-text available
The oncogenic role of STAT3 has been elucidated in a number of human malignancies including leukemia, lymphoma, malignant glioma and cancers of the breast, lung, and head and neck (HNSCC). Here we show that WP1066 has profound anti-neoplastic effects in HNSCC, mediated in part by suppression of JAK2-STAT3 signaling. WP1066 inhibited constitutive and inducible STAT3 phosphorylation in both dose- and time-dependant manners. Further, the nuclear translocation of STAT3 was completely inhibited, resulting in decreased DNA binding activity. In vivo testing of WP1066 in a nude mouse orthotopic model of HNSCC demonstrated significant anti-tumor effects, with histological evidence of decreased cellular proliferation and angiogenesis. Collectively, these data suggest that WP1066 suppresses squamous cell carcinoma cell growth, in part through its effects on JAK-STAT pathways, and establishes this small molecule as potentially efficacious agent in the treatment of HNSCC.
Article
Full-text available
Signal transducer and activator of transcription 3 (STAT3) is a latent cytoplasmic transcription factor responsive to cytokine signaling and tyrosine kinase oncoproteins by nuclear translocation when it is tyrosine-phosphorylated. We report that malignant transformation by activated Ras is impaired without STAT3, in spite of the inability of Ras to drive STAT3 tyrosine phosphorylation or nuclear translocation. Moreover, STAT3 mutants that cannot be tyrosine-phosphorylated, that are retained in the cytoplasm, or that cannot bind DNA nonetheless supported Ras-mediated transformation. Unexpectedly, STAT3 was detected within mitochondria, and exclusive targeting of STAT3 to mitochondria without nuclear accumulation facilitated Ras transformation. Mitochondrial STAT3 sustained altered glycolytic and oxidative phosphorylation activities characteristic of cancer cells. Thus, in addition to its nuclear transcriptional role, STAT3 regulates a metabolic function in mitochondria, supporting Ras-dependent malignant transformation.
Article
Full-text available
The signal transducers and activators of transcription (STAT) family members have been implicated in regulating the growth, differentiation, and death of normal and transformed cells in response to either extracellular stimuli, including cytokines and growth factors, or intracellular tyrosine kinases. c-myc expression is coordinately regulated by multiple signals in these diverse cellular responses. We show that STAT3 mostly mediates the rapid activation of the c-myc gene upon stimulation of the interleukin (IL)-6 receptor or gp130, a signal transducing subunit of the receptor complexes for the IL-6 cytokine family. STAT3 does so most likely by binding to cis-regulatory region(s) of the c-myc gene. We show that STAT3 binds to a region overlapping with the E2F site in the c-myc promoter and this site is critical for the c-myc gene promoter– driven transcriptional activation by IL-6 or gp130 signals. This is the first identification of the linkage between a member of the STAT family and the c-myc gene activation, and also explains how the IL-6 family of cytokines is capable of inducing the expression of the c-myc gene.
Article
Full-text available
Acquired epilepsy (i.e., after an insult to the brain) is often considered to be a progressive disorder, and the nature of this hypothetical progression remains controversial. Antiepileptic drug treatment necessarily confounds analyses of progressive changes in human patients with acquired epilepsy. Here, we describe experiments testing the hypothesis that development of acquired epilepsy begins as a continuous process of increased seizure frequency (i.e., proportional to probability of a spontaneous seizure) that ultimately plateaus. Using nearly continuous surface cortical and bilateral hippocampal recordings with radiotelemetry and semiautomated seizure detection, the frequency of electrographically recorded seizures (both convulsive and nonconvulsive) was analyzed quantitatively for approximately 100 d after kainate-induced status epilepticus in adult rats. The frequency of spontaneous recurrent seizures was not a step function of time (as implied by the "latent period"); rather, seizure frequency increased as a sigmoid function of time. The distribution of interseizure intervals was nonrandom, suggesting that seizure clusters (i.e., short interseizure intervals) obscured the early stages of progression, and may have contributed to the increase in seizure frequency. These data suggest that (1) the latent period is the first of many long interseizure intervals and a poor measure of the time frame of epileptogenesis, (2) epileptogenesis is a continuous process that extends much beyond the first spontaneous recurrent seizure, (3) uneven seizure clustering contributes to the variability in occurrence of epileptic seizures, and (4) the window for antiepileptogenic therapies aimed at suppressing acquired epilepsy probably extends well past the first clinical seizure.
Article
Full-text available
The gamma-aminobutyric acid (GABA) type A receptor (GABA(A)R) is the major inhibitory neurotransmitter receptor in the brain. Its multiple subunits show regional, developmental, and disease-related plasticity of expression; however, the regulatory networks controlling GABA(A)R subunit expression remain poorly understood. We report that the seizure-induced decrease in GABA(A)R alpha1 subunit expression associated with epilepsy is mediated by the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway regulated by brain-derived neurotrophic factor (BDNF). BDNF- and seizure-dependent phosphorylation of STAT3 cause the adenosine 3',5'-monophosphate (cAMP) response element-binding protein (CREB) family member ICER (inducible cAMP early repressor) to bind with phosphorylated CREB at the Gabra1:CRE site. JAK/STAT pathway inhibition prevents the seizure-induced decrease in GABA(A)R alpha1 abundance in vivo and, given that BDNF is known to increase the abundance of GABA(A)R alpha4 in a JAK/STAT-independent manner, indicates that BDNF acts through at least two distinct pathways to influence GABA(A)R-dependent synaptic inhibition.
Article
Full-text available
Repeated electroconvulsive seizure (ECS), a model for electroconvulsive therapy (ECT), exerts neuroprotective and proliferative effects in the brain. This trophic action of ECS requires inhibition of apoptotic activity, in addition to activation of survival signals. c-Myc plays an important role in apoptosis of neurons, in cooperation with the Bcl-2 family proteins, and its activity and stability are regulated by phosphorylation and ubiquitination. We examined c-Myc and related proteins responsible for apoptosis after repeated ECS. In the rat frontal cortex, repeated ECS for 10 days reduced the total amount of c-Myc, while increasing phosphorylation of c-Myc at Thr58, which reportedly induces degradation of c-Myc. As expected, ubiquitination of both phosphorylated and total c-Myc increased after 10 days ECS, suggesting that ECS may reduce c-Myc protein level via ubiquitination-proteasomal degradation. Bcl-2 family proteins, caspase, and poly(ADP-ribose) polymerase (PARP) were investigated to determine the consequence of down-regulating c-Myc. Protein levels of Bcl-2, Bcl-X(L), Bax, and Bad showed no change, and cleavage of caspase-3 and PARP were not induced. However, phosphorylation of Bad at Ser-155 and binding of Bad to 14-3-3 increased without binding to Bcl-X(L) after repeated ECS, implying that repeated ECS sequesters apoptotic Bad and frees pro-survival Bcl-XL. Taken together, c-Myc down-regulation via ubiquitination-proteasomal degradation and Bad inactivation by binding to 14-3-3 may be anti-apoptotic mechanisms elicited by repeated ECS in the rat frontal cortex. This finding further supports the trophic effect of ECS blocking apoptosis as a possible therapeutic effect of ECT.
Article
Full-text available
Two anionic fluorescein derivatives can be used for the simple and definitive localization of neuronal degeneration in brain tissue sections. Initial work on the first generation fluorochrome, Fluoro-Jade, demonstrated the utility of this compound for the detection of neuronal degeneration induced by a variety of well-characterized neurotoxicants, including kainic acid, 3-nitropropionic acid, isoniazid, ibogaine, domoic acid, and dizocilpine maleate (MK-801). After validation, the tracer was used to reveal previously unreported sites of neuronal degeneration associated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), methamphetamine, and d-fenfluramine. Preliminary findings with a second generation fluorescein derivative, Fluoro-Jade B, suggest that this tracer results in staining of optimal contrast and resolution in animals dosed with kainic acid. These 2 tracers can be combined with other histologic methods, including immunofluoresence and fluorescent Nissl stains. Recent preliminary findings on a number of specialized applications of Fluoro-Jade include the detection of apoptosis, amyloid plaques, astrocytes, and dead cells in tissue culture.
Article
Full-text available
Non-receptor and receptor tyrosine kinases, such as Src and EGF receptor (EGFR), are major inducers of vascular endothelial growth factor (VEGF), one of the most potent mediators of angiogenesis. While tyrosine kinases signal through multiple pathways, signal transducer and activation of transcription 3 (Stat3) is a point of convergence for many of these and is constitutively activated with high frequency in a wide range of cancer cells. Here, we show that VEGF expression correlates with Stat3 activity in diverse human cancer cell lines. An activated Stat3 mutant (Stat3C) up-regulates VEGF expression and stimulates tumor angiogenesis. Stat3C-induced VEGF up-regulation is abrogated when a Stat3-binding site in the VEGF promoter is mutated. Furthermore, interrupting Stat3 signaling with dominant-negative Stat3 protein or Stat3 antisense oligonucleotide in tumor cells down-regulates VEGF expression. Consistent with an important role of Stat3 in VEGF up-regulation induced by various oncogenic tyrosine kinases, v-Src-mediated VEGF expression is inhibited when Stat3 signaling is blocked. Moreover, chromatin immunoprecipitation assays indicate that Stat3 protein binds to the VEGF promoter in vivo and mutation of a Stat3-binding site in the VEGF promoter abrogates v-Src-induced VEGF promoter activity. These studies provide evidence that the VEGF gene is regulated directly by Stat3 protein, and indicate that Stat3 represents a common molecular target for blocking angiogenesis induced by multiple signaling pathways in human cancers.
Article
Full-text available
The Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway transmits information received from extracellular polypeptide signals, through transmembrane receptors, directly to target gene promoters in the nucleus, providing a mechanism for transcriptional regulation without second messengers. Evolutionarily conserved in eukaryotic organisms from slime molds to humans, JAK-STAT signaling appears to be an early adaptation to facilitate intercellular communication that has co-evolved with myriad cellular signaling events. This co-evolution has given rise to highly adapted, ligand-specific signaling pathways that control gene expression. In addition, the JAK-STAT signaling pathways are regulated by a vast array of intrinsic and environmental stimuli, which can add plasticity to the response of a cell or tissue.
Article
Full-text available
The precise mechanism responsible for the frequent overexpression of cyclinD1 in human head and neck squamous cell carcinoma (HNSCC) is not known. In view of the fact that signal transducers and activators of transcription 3 (Stat3) is often activated in HNSCC cells, we examined the effects of Stat3 on cyclin D1 expression and cell proliferation in the YCU-H891 HNSCC cell line that displays constitutive activation of Stat3. Expression of a dominant negative Stat3 construct in YCU-H891 cells inhibited proliferation, cyclin D1 promoter activity, and cellular levels of cyclin D1 mRNA and protein. The levels of the antiapoptotic Bcl-2 and Bcl-X(L) proteins were also inhibited. In 51 primary tumor samples from patients with squamous cell carcinoma of the p.o. tongue, there was a significant correlation between increased levels of the activated form of Stat3, phosphorylated-Stat3, and increased levels of cyclin D1 (P < 0.0001). Increased tumor levels of phosphorylated-Stat3 were also associated with lower survival rates (P < 0.01). This study provides the first evidence that in HNSCC, constitutive activation of Stat3 plays a causative role in overexpression of cyclin D1, and in clinical studies, Stat3 activation may provide a novel prognostic factor. Furthermore, agents that target Stat3 may be useful in the treatment of HNSCC.
Article
Full-text available
Extracellular proteins bound to cell-surface receptors can change nuclear gene expression patterns in minutes, with far-reaching consequences for development, cell growth and homeostasis. The signal transducer and activator of transcription (STAT) proteins are among the most well studied of the latent cytoplasmic signal-dependent transcription-factor pathways. In addition to several roles in normal cell decisions, dysregulation of STAT function contributes to human disease, making the study of these proteins an important topic of current research.
Article
Full-text available
Much remains unknown about the natural history of intractable localization-related epilepsy, including how long it typically takes before intractability becomes evident. This information could guide the design of future studies, resolve certain discrepancies in the literature, and provide more accurate information about long-term prognosis. Individuals evaluated for resective surgery for refractory localization-related epilepsy were prospectively identified at the time of initial surgical evaluation at seven surgical centers (between 1996 and 2001). The latency time between onset of epilepsy and failure of second medication and history of remission (>/=1 year seizure-free) before surgical evaluation were examined with respect to age at onset, hippocampal atrophy, febrile seizures, and surgical site. In the 333 patients included in the analysis, latency time was 9.1 years (range 0 to 48) and 26% reported a prior remission before surgery. A prior remission of >/=5 years was reported by 8.5% of study participants. Younger age at onset was strongly associated with longer latency time (p < 0.0001) and higher probability of past remission (p < 0.0001). In multivariable analyses, age at onset remained as the most important explanatory variable of both latency time and prior remission. A substantial proportion of localization-related epilepsy may not become clearly intractable for many years after onset. This is especially true of epilepsy of childhood and early adolescent onset. If prospective studies confirm these findings and the underlying mechanisms behind these associations become understood, this raises the possibility of considering interventions that might interrupt such a process and some day prevent some forms of epilepsy from becoming intractable.
Article
We investigated the activation and cellular distribution of two signaling pathways, the signal transducers and activators of transcription (STATs) and mitogen-activated protein kinases (MAPKs) following kainic acid (KA)-induced seizures, in relation to the expression of gp 130, a common cytokine signal transducer for the interleukin (IL)-6 family of cytokines. Rapid and short-lasting upregulation of gp130 was observed in the granule cells. This became evident in astrocytes by 3 h, increased progressively to peak at 3 days, and was sustained for 10 days. STATs, including STAT1 and STAT3, and p42/44 MAPK were activated in distinct cellular and spatial distributions within the hippocampus following seizures. A rapid and sustained seizure-induced activation of STAT3 and STAT1, revealed by nuclear STAT3 and STAT1 immumoreactivities, was observed exclusively in reactive astrocytes in the hippocampus, nearly coinciding with the time course of gp 130 expression; however, STAT3 activation was greater. In contrast, seizure induced the rapid and transient activation of p42/44 MAPK in a subpopulation of hippocampal neurons and in astrocytes, although with weaker staining intensity. Two signaling pathways involving gp130, STATs and MAPK, were differentially activated in reactive astrocytes after KA injection, indicating that STATs and MAPK may differentially mediate the astroglial reaction in the rat hippocampus after KA-induced seizures.
Article
Approximately 1 in 26 people will develop epilepsy at some point in their lives. Although epilepsy is one of the nation's most common neurological disorders, public understanding is limited. A complex spectrum of disorders, epilepsy affects an estimated 2.2million people in the United States. Living with epilepsy is about more than just seizures; it is often defined in practical terms, such as challenges, uncertainties, and limitations in school, social situations, employment, driving, and independent living. People with epilepsy are also faced with health and community services that are fragmented, uncoordinated, and difficult to obtain. The Institute of Medicine's report (2012) [1], Epilepsy across the spectrum: promoting health and understanding, examines the public health dimensions of epilepsy with a focus on (a) public health surveillance and data collection and integration; (b) population and public health research; (c) health policy, health care, and human services; and (d) education for providers, people with epilepsy and their families, and the public. The report's recommendations range from the expansion of collaborative epilepsy surveillance efforts to the independent accreditation of epilepsy centers, to the coordination of public awareness efforts, and to the engagement of people with epilepsy and their families in education, dissemination, and advocacy activities. Given the current gaps in epilepsy knowledge, care, and education, there is an urgent need to take action-across multiple dimensions-to improve the lives of people with epilepsy and their families. The realistic, feasible, and action-oriented recommendations in this report can help enable short- and long-term improvements for people with epilepsy.
Article
Abstract The gamma-aminobutyric acid (GABA) type A receptor (GABA(A)R) is responsible for most fast synaptic inhibition in the adult brain. The GABA(A)R protein is composed of multiple subunits that determine the distribution, properties, and dynamics of the receptor. Several studies have shown that the Janus kinase/signal transducer and activator of transcription (JaK/STAT) and early growth response 3 (Egr3) signaling pathways can alter GABA(A)R subunit expression after status epilepticus (SE). In this study we investigated changes in these pathways after experimental TBI in the rat using a lateral fluid percussion injury (FPI) model. Our results demonstrated changes in the expression of several GABA(A)R subunit levels after injury, including GABA(A)R α1 and α4 subunits. This change appears to be transcriptional, and there is an associated increase in the phosphorylation of STAT3, and an increase in the expression of Egr3 and inducible cAMP element repressor (ICER) after FPI. These findings suggest that the activation of the JaK/STAT and Egr3 pathways after TBI may regulate injury-related changes in GABA(A)R subunit expression.
Article
Gel retardation electrophoresis revealed that binding of a radiolabeled double stranded oligo-nucleotide probe for the nuclear transcription factor activator protein-1 (AP1) was markedly potentiated 2 h after the intraperitoneal injection of kainic acid (KA) at a dose range of 10–40 mg/kg in a dose-dependent manner in the murine hippocampus. The potentiation was seen in a manner independent of the crisis of convulsive seizures following the administration of KA at different doses. At the highest dose employed, the systemic KA significantly potentiated the AP1 binding in most central discrete structures examined except the cerebellum. In contrast, KA significantly potentiated binding of a radiolabeled probe for cyclic AMP response element binding protein (CREB) in a dose-dependent fashion in the hippocampus, without altering that in other parts of murine brain. No significant alteration was detected in binding of a probe for c-Myc in any brain regions examined 2 h after the administration of KA at different doses. However, immunoblotting analysis demonstrated that KA was ineffective in altering endogenous levels of both CREB and CREB phosphorlyated at serine133 in the hippocampus and cerebellum. These results suggest that in vivo systemic KA signals may be selectively transduced to nuclear AP1 in the hippocampus through a mechanism different from phosphorylation of CREB at serine133 in murine brain. Copyright © 1996 Elsevier Science Ltd.
Article
JAK-STAT is the major downstream signal pathway of interleukin-6 (IL-6) cytokine family and is regulated by Tyr705 phosphorylation of Stat3. The present study examined the extent and the localization of phosphorylated Stat3 protein in brain tissue after focal ischemia in rats. The localizations of unphosphorylated and phosphorylated Stat3 were immunohistochemically examined in rats after 0.5 to 168 h of reperfusion following 1.5 h of middle cerebral artery occlusion (MCAO), induced by the intraluminal suture method. Absolute phosphorylated Stat3 immunoreactive cell counts were made in the cerebral cortex (ischemic core, peri-ischemia region, and contralareral cortex) and lateral striatal regions on both the ischemic and the contralateral sides. Stat3 protein was localized diffusely in cortical and striatal neurons in the sham-operated animals. Although weak Stat3 staining was detected in damaged neurons in the ischemic region, activated microglia, astrocytes, and endothelial cells clearly expressed Stat3 in this region. On the other hand, the sham group showed no phosphorylated Stat3 immunoreactivity. Phosphorylated Stat3 immunoreactivity was first detected in neurons after 3.5 h of reperfusion in each cortical and striatal region. Thereafter, Stat3 phosphorylation was marked in neurons in the peri-infarct region, peaked at 24 h, and then gradually declined throughout the reperfusion period. Endothelial cells expressed phosphorylated Stat3 in the ischemic core at 48 h of reperfusion. To identify the cellular source of phosphorylated Stat3, lectin histochemical study and immunohistochemical study with anti-microtubule-associated proten-2 and anti-glial fibrillary acidic protein antibodies were carried out. Double-staining immunohistochemistry with these cellular makers revealed phosphorylated Stat3 to be present in neurons, but in neither astrocytes nor microglia/macrophages. These results were also confirmed be western blot analysis. The present results indicate that Stat3 activation occurs in neurons and endothelial cells only during post-ischemic reperfusion despite widespread expression of IL-6 cytokines.
Article
Since the discovery of neural precursor cells (NPCs) in the adult mammalian brain, there has been a lot of excitement surrounding the potential for regeneration in the adult brain. For instance, many studies have shown that a significant number of NPCs will migrate to a site of injury and differentiate into all of the neural lineages. However, one of the main challenges affecting endogenous neural regeneration is that many of the NPCs that migrate to the injury site ultimately undergo apoptosis. Therefore, we sought to determine whether myeloid cell leukemia-1 (Mcl-1), an anti-apoptotic Bcl-2 protein, would promote the survival of adult NPCs by impeding apoptosis. To do this, we first confirmed that Mcl-1 is endogenously expressed within the adult NPC population using BrdU labeling assays. Next, we conditionally deleted Mcl-1 in adult NPCs using cre/lox technology and expressed Cre from the NPC-specific promoter Nestin. In vitro, cells that had Mcl-1 conditionally deleted had a 2-fold increase in apoptosis when compared to controls. In vivo, we used electroporation to conditionally delete Mcl-1 in adult NPCs and assessed apoptosis at 72h. after electroporation. As in our in vitro results, there was a 2-fold increase in apoptosis when Mcl-1 was conditionally deleted. Finally, we found that Mcl-1 over-expression reduced the endogenous rate of adult NPC apoptosis 2-fold in vitro. Collectively, these results demonstrate that Mcl-1 is crucial for the survival of adult NPCs and may be a promising target for future neural regeneration therapies.
Article
J. Neurochem. (2012) 120, 710–720. Astrocytes respond to trauma by stimulating inflammatory signaling. In studies of cerebral ischemia and spinal cord injury, astrocytic signaling is mediated by the cytokine receptor glycoprotein 130 (gp130) and Janus kinase (Jak) which phosphorylates the transcription factor signal transducer and activator of transcription-3 (STAT3). To determine if STAT3 is activated after traumatic brain injury (TBI), adult male Sprague–Dawley rats received moderate parasagittal fluid-percussion brain injury or sham surgery, and then the ipsilateral cortex and hippocampus were analyzed at various post-traumatic time periods for up to 7 days. Western blot analyses indicated that STAT3 phosphorylation significantly increased at 30 min and lasted for 24 h post-TBI. A significant increase in gp130 and Jak2 phosphorylation was also observed. Confocal microscopy revealed that STAT3 was localized primarily within astrocytic nuclei. At 6 and 24 h post-TBI, there was also an increased expression of STAT3 pathway-related genes: suppressor of cytokine signaling 3, nitric oxide synthase 2, colony stimulating factor 2 receptor β, oncostatin M, matrix metalloproteinase 3, cyclin-dependent kinase inhibitor 1A, CCAAT/enhancer-binding protein β, interleukin-2 receptor γ, interleukin-4 receptor α, and α-2-macroglobulin. These results clarify some of the signaling pathways operative in astrocytes after TBI and demonstrate that the gp130-Jak2-STAT3 signaling pathway is activated after TBI in astrocytes.
Article
Activation of signal transducer and activator of transcription 3 (STAT3) is associated with poor clinical outcome of glioblastoma (GBM). However, the role of STAT3 in resistance to alkylator-based chemotherapy remains unknown. Here, we retrospectively analyzed the phosphorylated STAT3 (p-STAT3) profile of 68 GBM patients receiving alkylator therapy, identifying p-STAT3 as an independent unfavorable prognostic factor for progression-free and overall survival. Additionally, elevated p-STAT3 expression correlated with resistance to alkylator therapy. In vitro analysis revealed that U251 and U87 human glioma cells were refractory to treatment with the common alkylating agent temozolomide (TMZ), with only a modest impact on AKT and β-catenin activation in the context of high p-STAT3. Inhibition of STAT3 in these cells significantly enhanced the effect of TMZ. Inhibition of STAT3 dramatically decreased the IC50 of TMZ, increasing TMZ-induced apoptosis while up-regulating expression of Bcl-2 and down-regulating expression of Bax. Furthermore, inhibition of STAT3 increased TMZ-induced G₀-G₁ arrest and decreased Cyclin D1 expression compared to TMZ alone. Together, these results indicate that inhibition of STAT3 sensitizes glioma cells to TMZ, at least in part, by blocking the p-AKT and β-catenin pathways. These findings strongly support the hypothesis that STAT3 inhibition significantly improves the clinical efficacy of alkylating agents.
Article
Glial Fibrillary Acidic Protein (GFAP) is regarded as a marker of reactive astrogliosis. Recent studies have demonstrated that signal transducer and activator of transcription-3, STAT3 regulates GFAP expression after brain injuries. However, whether STAT3 controls astrogliosis in epilepsy is not clear. In this study, we measured p-STAT3 and GFAP expression during the epileptic process using immunohistochemistry, Western blotting and immunofluorescence. Both p-STAT3 and GFAP expression were highly expressed in the rat hippocampus during different phases of the epileptic process. The augmentation of GFAP expression was inhibited by AG490, a janus kinase 2 (JAK2, an upstream gene of STAT3) inhibitor. The coexpression of p-STAT3 and GFAP was detected in the epileptic rat hippocampus and temporal neocortex of patients. These findings indicate that epilepsy involves the activation of STAT3 that up-regulates the expression of GFAP, which may play an important role in epileptogenesis.
Daily electrical stimulations of the amygdala and hippocampus at intensities sufficient to evoke after-discharges (ADs) resulted in the development of motor seizures, which could not initially be evoked by these stimulations. The triggering of ADs was critical for this development, as well as for the development of permanent changes in the characteristics of the AD. The wave form of the AD "spikes" became more complex. The frequency of these spikes and the duration of AD increased. The amplitude of the AD spikes increased in the structure stimulated as well as in secondary structures to which the AD was "projected". This increase in amplitude of "projected" spikes often correlated with the appearance of motor seizures. Other electrographic developments are discussed including the appearance of spontaneous "inter-ictal" spiking in the amygdala. It was found that the development of motor seizures by stimulation of the amygdala resulted in an increased ability of the contralateral amygdala, and the septal area, but not of the hippocampus, to drive motor seizures when stimulated ("transfer"). Motor seizure development in the hippocampus transferred to the contralateral hippocampus. These developments were shown, by means of control subjects, with lesions in the primary focus to involve changes outside the primary focus. The implications of these developments with respect to seizure development are discussed.