[show abstract][hide abstract] ABSTRACT: Parkinson's disease (PD) is a devastating neurodegenerative disorder characterized by degeneration of the nigrostriatal dopaminergic pathway. Because the current therapies only lead to temporary, limited improvement and have severe side effects, new approaches to treat PD need to be developed. To discover new targets for potential therapeutic intervention, a chemical genetic approach involving the use of small molecules as pharmacological tools has been implemented. First, a screening of an in-house chemical library on a well-established cellular model of PD was done followed by a detailed pharmacological analysis of the hits. Here, we report the results found for the small heterocyclic derivative called SC001, which after different enzymatic assays was revealed to be a new glycogen synthase kinase-3 (GSK-3) inhibitor with IC(50) = 3.38 ± 0.08 μM. To confirm that GSK-3 could be a good target for PD, the evaluation of a set of structurally diverse GSK-3 inhibitors as neuroprotective agents for PD was performed. Results show that inhibitors of GSK-3 have neuroprotective effects in vitro representing a new pharmacological option for the disease-modifying treatment of PD. Furthermore, we show that SC001 is able to cross the blood-brain barrier, protects dopaminergic neurons, and reduces microglia activation in in vivo models of Parkinson disease, being a good candidate for further drug development.
ACS Chemical Neuroscience 02/2013; 4(2):350-60. · 3.87 Impact Factor
[show abstract][hide abstract] ABSTRACT: Glycogen synthase kinase-3 (GSK-3) is a serine/threonine kinase originally identified as a regulator of glycogen metabolism but it also plays a pivotal role in numerous cellular functions, including differentiation, cell cycle regulation, and proliferation. The dentate gyrus of the hippocampus, together with the subventricular zone of the lateral ventricles, is one of the regions in which neurogenesis takes place in the adult brain. Here, using a chemical genetic approach that involves the use of several diverse inhibitors of GSK-3 as pharmacological tools, we show that inhibition of GSK-3 induces proliferation, migration, and differentiation of neural stem cells toward a neuronal phenotype in in vitro studies. Also, we demonstrate that inhibition of GSK-3 with the small molecule NP03112, called tideglusib, induces neurogenesis in the dentate gyrus of the hippocampus of adult rats. Taken together, our results suggest that GSK-3 should be considered as a new target molecule for modulating the production and integration of new neurons in the hippocampus as a treatment for neurodegenerative diseases or brain injury and, consequently, its inhibitors may represent new potential therapeutic drugs in neuroregenerative medicine.
ACS Chemical Neuroscience 11/2012; 3(11):963-71. · 3.87 Impact Factor
[show abstract][hide abstract] ABSTRACT: We analyzed the role of the cannabinoid system in the cognitive deficits caused by developmentally-induced hypothyroidism. We studied in control and hypothyroid rats the effect of a cannabinoid agonist on spatial memory, hippocampal phosphorylation of CREB and expression of early genes. Our results show that, 1-basal hippocampal expression of early genes and spatial learning are decreased in hypothyroid rats; 2-hypothyroid rats are very sensitive to cannabinoid agonists. Low dose of cannabinoid agonist ineffective in controls altered spatial memory, CREB's phosphorylation and early gene expression in hypothyroids. These effects are not due a change in CB1 receptor (CB1R) content. 3-Treatment of hypothyroid rats with thyroid hormones normalized the biochemical and behavioral responses to cannabinoid agonists but did not correct the low basal levels of early gene transcripts and the deficits in spatial learning. All these data suggest that the hippocampal deregulation of early genes expression could play an important role in the basal cognitive deficits of hypothyroid rats.
Molecular and Cellular Endocrinology 10/2012; · 4.04 Impact Factor
[show abstract][hide abstract] ABSTRACT: Oxidative stress plays an important role in neuronal death in neurodegenerative disorders such as Parkinson's disease (PD). Hydroxyphenyl nitrones, derivatives of the nitrone spin trap alpha-phenyl-N-tert-butylnitrone (PBN), were synthesized and their antioxidant, anti-inflammatory and neuroprotective activity in neural cells evaluated. These hydroxyphenyl nitrones 5-7 were synthesized by reaction of the corresponding hydroxybenzaldehyde with N-tert-butyl hydroxylamine under microwave irradiation. They showed good peroxyl free radical scavenger capacities, analyzed by oxygen radical absorbance capacity (ORAC). Also inhibited peroxynitrite-mediated tyrosine nitration of alpha-synuclein in vitro and protected human neuroblastoma (SH-SY5Y) cells against SIN-1 and 6-OHDA toxicity when micromolar concentrations were used. Besides, the hydroxyphenyl nitrones evaluated showed anti-inflammatory activity modulating nitrite production in primary neural cell cultures of astrocytes and microglia treated with lipopolysaccharide (LPS), a potent inflammatory agent. These experimental data suggest a potential therapeutic use of these hydroxyphenyl nitrones against oxygen and nitrogen reactive species involved in neurodegenerative pathology.
European journal of medicinal chemistry 10/2012; 58C:44-49. · 3.27 Impact Factor
[show abstract][hide abstract] ABSTRACT: Increased levels of glutamate causing excitotoxic damage accompany many neurological disorders. A well-characterized model of excitotoxic damage involves administration of kainic acid (KA), which causes limbic seizure activity and subsequent neuronal death, particularly in the CA1 and CA3 areas of the hippocampus. Inhibition of the enzyme glycogen synthase kinase-3 (GSK-3) and cAMP levels might play an important role in neuroprotection. As intracellular cAMP levels depend, in part, on the activity of the phosphodiesterase enzymes (PDEs), these enzymes have recently emerged as potential therapeutic targets for the treatment of several diseases. In previous works, we have shown a potent anti-inflammatory and neuroprotective effect of GSK-3 inhibition in a model of excitotoxicity, as well as a reduction of nigrostriatal dopaminergic neuronal cell death after phosphodiesterase 7 inhibition, which leads to an increase in cAMP levels. This study was undertaken to determine whether simultaneous inhibition of GSK-3 and PDE-7 by a novel 5-imino-1,2,4-thiadiazole compound, named VP1.14, could prevent the massive neuronal loss in the hippocampus evoked by intrahippocampal injection of KA. Here, we show that rats treated with VP1.14 showed a reduced inflammatory response after KA injection, and exhibited a significant reduction in pyramidal cell loss in the CA1 and CA3 areas of the hippocampus. Studies with hippocampal HT22 cells in vitro also showed a clear neuroprotective effect of VP1.14 and an anti-inflammatory effect shown by a decrease in the nitrite liberation and in the expression of pro-inflammatory cytokines by primary cultures of astrocytes treated with lipopolysaccharide.
Journal of Neurochemistry 07/2012; 122(6):1193-202. · 3.97 Impact Factor
[show abstract][hide abstract] ABSTRACT: Phosphodiesterase (PDE) 7 is involved in proinflammatory processes, being widely expressed both on lymphocytes and on certain brain regions. Specific inhibitors of PDE7 have been recently reported as potential new drugs for the treatment of neurological disorders because of their ability to increase intracellular levels of cAMP and thus to modulate the inflammatory process, as a neuroprotective well-established strategy. Multiple sclerosis is an unmet disease in which pathologies on the immune system, T-cells, and specific neural cells are involved simultaneously. Therefore, PDE7 inhibitors able to interfere with all these targets may represent an innovative therapy for this pathology. Here, we report a new chemically diverse family of heterocyclic PDE7 inhibitors, discovered and optimized by using molecular modeling studies, able to increase cAMP levels in cells, decrease inflammatory activation on primary neural cultures, and also attenuate the clinical symptoms in the experimental autoimmune encephalomyelitis (EAE) mouse model. These results led us to propose the use of PDE7 inhibitors as innovative therapeutic agents for the treatment of multiple sclerosis.
Journal of Medicinal Chemistry 03/2012; 55(7):3274-84. · 5.61 Impact Factor
[show abstract][hide abstract] ABSTRACT: Cumulative evidence strongly supports that glycogen synthase kinase-3 (GSK-3) is a pathogenic molecule when it is up-dysregulated, emerging as an important therapeutic target in severe unmet human diseases. GSK-3 specific inhibitors might be promising effective drugs for the treatment of devastating pathologies such as neurodegenerative diseases, stroke, and mood disorders. As GSK-3 has the ability to phosphorylate primed substrates, small molecules able to bind to this site should be perfect drug candidates, able to partially block the activity of the enzyme over some specific substrates. Here, we report substituted 5-imino-1,2,4-thiadiazoles as the first small molecules able to inhibit GSK-3 in a substrate competitive manner. These compounds are cell permeable, able to decrease inflammatory activation and to selectively differentiate neural stem cells. Overall, 5-imino-1,2,4-thiadiazoles are presented here as new molecules able to decrease neuronal cell death and to increase endogenous neurogenesis blocking the GSK-3 substrate site.
Journal of Medicinal Chemistry 02/2012; 55(4):1645-61. · 5.61 Impact Factor
[show abstract][hide abstract] ABSTRACT: A simple and efficient synthetic method for the preparation of quinazoline type phosphodiesterase 7 (PDE7) inhibitors, based on microwave irradiation, has been developed. The use of this methodology improved yields and reaction times, providing a scalable procedure. These compounds are pharmacologically interesting because of their in vivo efficacy both in spinal cord injury and Parkinson's disease models, as shown in previous studies from our group. Herein we describe for the first time that administration of one of the PDE7 inhibitors here optimized, 3-phenyl-2,4-dithioxo-1,2,3,4-tetrahydroquinazoline (compound 5), ameliorated brain damage and improved behavioral outcome in a permanent middle cerebral artery occlusion (pMCAO) stroke model. Furthermore, we demonstrate that these PDE7 inhibitors are potent anti-inflammatory as well as neuroprotective agents in primary cultures of neural cells. These results led us to propose PDE7 inhibitors as a new class of therapeutic agents for neuroprotection.
European journal of medicinal chemistry 11/2011; 47(1):175-85. · 3.27 Impact Factor
[show abstract][hide abstract] ABSTRACT: C/EBPβ is a leucine-zipper transcription factor implicated in the control of metabolism, development, cell differentiation, and proliferation. However, it remains unclear its role in tumor development. Here, we show that down-regulation of C/EBPβ by RNA interference inhibits proliferation in the GL261 murine glioblastoma cell line, induces an arrest of the cell cycle at the G0/G1 boundary, and diminishes their transformation capacity and migration. In addition, we show that C/EBPβ regulates the expression of several DNA damage response- and invasion-related genes. Lastly, C/EBPβ depletion significantly retards tumor onset and prolongs survival in a murine orthotopic brain tumor model. Immunohistochemical analysis revealed a significant diminution of proliferating cell nuclear antigen (PCNA) labeling in tumors derived from C/EBPβ-depleted GL261 cells compared with that in controls. These results show, for the first time, the dependence of glioma cells on C/EBPβ and suggest a potential role of this transcription factor in glioma development.
[show abstract][hide abstract] ABSTRACT: Peroxisome proliferator-activated receptor gamma (PPARγ) belongs to a family of ligand-activated nuclear receptors and its ligands are known to control many physiological and pathological situations. Its role in the central nervous system has been under intense analysis during the last years. Here we show a novel function for PPARγ in controlling stem cell expansion in the adult mammalian brain. Adult rats treated with pioglitazone, a specific ligand of PPARγ, had elevated numbers of proliferating progenitor cells in the subventricular zone and the rostral migratory stream. Electron microscopy analysis also showed important changes in the subventricular zone ultrastructure of pioglitazone-treated animals including an increased number of migratory cell chains. These results were further confirmed in vitro. Neurosphere assays revealed significant increases in the number of neurosphere forming cells from pioglitazone- and rosiglitazone (two specific ligands of PPARγ receptor)-treated cultures that exhibited enhanced capacity for cell migration and differentiation. The effects of pioglitazone were blocked by the PPARγ receptor antagonists GW9662 and T0070907, suggesting that its effects are mediated by a mechanism dependent on PPARγ activation. These results indicate for the first time that activation of PPARγ receptor directly regulates proliferation, differentiation, and migration of neural stem cells in vivo.
[show abstract][hide abstract] ABSTRACT: The dentate gyrus of the hippocampus is one of the regions in which neurogenesis takes place in the adult brain. We have previously demonstrated that CCAAT/enhancer binding protein β (C/EBPβ) is expressed in the granular layer of the dentate gyrus of the adult mouse hippocampus. Taking into account the important role of C/EBPβ in the consolidation of long term memory, the fact that newborn neurons in the hippocampus contribute to learning and memory processes, and the role of this transcription factor, previously demonstrated by our group, in regulating neuronal differentiation, we speculated that this transcription factor could regulate stem/progenitor cells in this region of the brain.
Here, we show, using C/EBPβ knockout mice, that C/EBPβ expression is observed in the subset of newborn cells that proliferate in the hippocampus of the adult brain. Mice lacking C/EBPβ present reduced survival of newborn cells in the hippocampus, a decrease in the number of these cells that differentiate into neurons and a diminished number of cells that are proliferating in the subgranular zone of the dentate gyrus. These results were further confirmed in vitro. Neurosphere cultures from adult mice deficient in C/EBPβ present less proliferation and neuronal differentiation than neurospheres derived from wild type mice.
In summary, using in vivo and in vitro strategies, we have identified C/EBPβ as a key player in the proliferation and survival of the new neurons produced in the adult mouse hippocampus. Our results support a novel role of C/EBPβ in the processes of adult hippocampal neurogenesis, providing new insights into the mechanisms that control neurogenesis in this region of the brain.
PLoS ONE 01/2011; 6(10):e24842. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: Phosphodiesterase 7 plays a major role in down-regulation of protein kinase A activity by hydrolyzing cAMP in many cell types. This cyclic nucleotide plays a key role in signal transduction in a wide variety of cellular responses. In the brain, cAMP has been implicated in learning, memory processes and other brain functions.
Here we show a novel function of phosphodiesterase 7 inhibition on nigrostriatal dopaminergic neuronal death. We found that S14, a heterocyclic small molecule inhibitor of phosphodiesterase 7, conferred significant neuronal protection against different insults both in the human dopaminergic cell line SH-SY5Y and in primary rat mesencephalic cultures. S14 treatment also reduced microglial activation, protected dopaminergic neurons and improved motor function in the lipopolysaccharide rat model of Parkinson disease. Finally, S14 neuroprotective effects were reversed by blocking the cAMP signaling pathways that operate through cAMP-dependent protein kinase A.
Our findings demonstrate that phosphodiesterase 7 inhibition can protect dopaminergic neurons against different insults, and they provide support for the therapeutic potential of phosphodiesterase 7 inhibitors in the treatment of neurodegenerative disorders, particularly Parkinson disease.
PLoS ONE 01/2011; 6(2):e17240. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: Thyroid hormones are essential for normal brain development, and multiple alterations at behavioral, cognitive, cellular, and molecular levels have been described in animals made hypothyroid during development. Here we analyzed the effect of developmental hypothyroidism in the rat on the sensitivity to kainic acid-induced limbic seizures and the expression of kainate receptors in the hippocampus. Our results show that hypothyroid rats are extremely sensitive to the proconvulsant and neurotoxic effects of kainic acid (KA). Hypothyroid rats entered in status epilepticus at a dose of KA three times lower than that required to reach status epilepticus in control animals. In accordance with this, high levels of glial activation and neuronal loss after low KA dose injections were observed only in the hippocampus of hypothyroid rats. These effects correlated with an increased expression of kainate receptor subunits, excluding GluR5, in the hippocampus of hypothyroid animals. The concentrations of GluR6, GluR7, KAR1, and KAR2 (ionotropic glutamate receptor subunits of the kainic acid subtype) mRNAs were increased between 50 and 250% in hypothyroid animals relative to the values in controls. In agreement with these results, Western blot and immunohistochemical analysis showed a clear increase in the hippocampal content of GluR6/7 proteins in hypothyroid animals.
[show abstract][hide abstract] ABSTRACT: Thiadiazolidinones (TDZD) are small heterocyclic compounds first described as non-ATP competitive inhibitors of glycogen synthase kinase 3β (GSK-3β). In this study, we analyzed the effects of 4-benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione (TDZD-8), on murine GL261 cells growth in vitro and on the growth of established intracerebral murine gliomas in vivo.
Our data show that TDZD-8 decreased proliferation and induced apoptosis of GL261 glioblastoma cells in vitro, delayed tumor growth in vivo, and augmented animal survival. These effects were associated with an early activation of extracellular signal-regulated kinase (ERK) pathway and increased expression of EGR-1 and p21 genes. Also, we observed a sustained activation of the ERK pathway, a concomitant phosphorylation and activation of ribosomal S6 kinase (p90RSK) and an inactivation of GSK-3β by phosphorylation at Ser 9. Finally, treatment of glioblastoma stem cells with TDZD-8 resulted in an inhibition of proliferation and self-renewal of these cells.
Our results suggest that TDZD-8 uses a novel mechanism to target glioblastoma cells, and that malignant progenitor population could be a target of this compound.
PLoS ONE 01/2010; 5(11):e13879. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: 15-Deoxi-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)) is known to play an important role in the pathophysiology of carcinogenesis, however, the molecular mechanisms underlying these effects are not yet fully understood. Recently, we have shown that 15d-PGJ(2) is a potent inducer of breast cancer cell death and that this effect is associated with a disruption of the microtubule cytoskeletal network. Here, we show that treatment of the MCF-7 breast cancer cell line with 15d-PGJ(2) induces an accumulation of cells in the G(2)/M compartment of the cell cycle and a marked disruption of the microtubule network. 15d-PGJ(2) treatment causes mitotic abnormalities that consist of failure to form a stable metaphase plate, incapacity to progress through anaphase, and failure to complete cytokinesis. 15d-PGJ(2) binds to tubulin through the formation of a covalent adduct with at least four cysteine residues in alpha- and beta-tubulin, as detected by hybrid triple-quadrupole mass spectrometry analysis. Overall, these results support the hypothesis that microtubule disruption and mitotic arrest, as a consequence of the binding of 15d-PGJ(2) to tubulin, can represent one important pathway leading to breast cancer cell death.
[show abstract][hide abstract] ABSTRACT: Kainic acid (KA)-induced status epilepticus (SE) is a well-characterized model of excitotoxic neuronal injury. Excitotoxicity results from activation of specific glutamate receptors, with resultant elevation of intracellular Ca(2+). The CA1 and CA3 subregions of the hippocampus are especially vulnerable to KA, and this pattern of neuronal injury resembles that occurring in patients with temporal lobe epilepsy. Calcium plays an essential role in excitotoxicity, and accordingly calcium channel inhibitors have been shown to have protective effects in various experimental models of epilepsy and brain injury. Moreover, they also potentiate the antiseizure efficacy of conventional antiepileptic drugs. This study was undertaken to determine whether NP04634, a novel compound, reported as a non-L-type voltage-sensitive calcium channel (VSCC) inhibitor, could prevent the entrance in SE and the neuronal loss evoked by intraperitoneal injection of KA. Our results show that intragastrical administration of NP04634 reduced the percentage of rats that entered SE after KA injection, increased the latency of SE entry, and significantly reduced the mortality of rats that entered SE. Also, NP04634 prevented the loss of hippocampal CA1 and CA3 pyramidal neurons and reduced the gliosis induced by KA. These results point to a potential anticonvulsant and neuroprotective role for NP04634.
Journal of Neuroscience Research 07/2009; 87(16):3687-96. · 2.97 Impact Factor
[show abstract][hide abstract] ABSTRACT: PDE7 inhibitors regulate pro-inflammatory and immune T-cell functions, and are a potentially novel class of drugs especially useful in the treatment of a wide variety of immune and inflammatory disorders. Starting from our lead family of thioxoquinazolines, we designed, synthesized, and characterized a novel series of thioxoquinazoline derivatives. Many of these compounds showed inhibitory potencies at sub-micromolar levels against the catalytic domain of PDE7A1 and at the micromolar level against PDE4D2. Cell-based studies showed that these compounds not only increased intracellular cAMP levels, but also had interesting anti-inflammatory properties within a therapeutic window. The in silico data predict that these compounds are capable of the crossing the blood-brain barrier. The X-ray crystal structure of the PDE7A1 catalytic domain in complex with compound 15 at a resolution of 2.4 A demonstrated that hydrophobic interactions at the active site pocket are a key feature. This structure, together with molecular modeling, provides insight into the selectivity of the PDE inhibitors and a template for the discovery of new PDE7 or PDE7/PDE4 dual inhibitors.
[show abstract][hide abstract] ABSTRACT: Thyroid hormone plays a critical role in mitochondrial biogenesis in two areas of the developing brain, the cerebral cortex and the striatum. Here we analyzed, in the cerebral cortex of neonatal rats, the effect of hypothyroidism on the biogenesis in free and synaptosomal mitochondria by analyzing, in isolated mitochondria, the activity of respiratory complex I, oxidative phosphorylation, oxygen consumption, and the expression of mitochondrial genome. In addition, we studied the effect of thyroid hormone in oxygen consumption in vivo by determining metabolic flow through (13)C nuclear magnetic resonance spectroscopy. Our results clearly show that in vivo, hypothyroidism markedly reduces oxygen consumption in the neural population of the cerebral cortex. This effect correlates with decreased free mitochondria biogenesis. In contrast, no effect was observed in the biogenesis in synaptosomal mitochondria. The parameters analyzed were markedly improved after T(3) administration. These results suggest that a reduced biogenesis and the subsequent reduction of respiratory capacity in free mitochondria could be the underlying cause of decreased oxygen consumption in the neurons of the cerebral cortex of hypothyroid neonates.
[show abstract][hide abstract] ABSTRACT: Alterations in motor functions are well-characterized features observed in humans and experimental animals subjected to thyroid hormone dysfunctions during development. Here we show that congenitally hypothyroid rats display hyperactivity in the adult life. This phenotype was associated with a decreased content of cannabinoid receptor type 1 (CB(1)) mRNA in the striatum and a reduction in the number of binding sites in both striatum and projection areas. These findings suggest that hyperactivity may be the consequence of a thyroid hormone deficiency-induced removal of the endocannabinoid tone, normally acting as a brake for hyperactivity at the basal ganglia. In agreement with the decrease in CB(1) receptor gene expression, a lower cannabinoid response, measured by biochemical, genetic and behavioral parameters, was observed in the hypothyroid animals. Finally, both CB(1) receptor gene expression and the biochemical and behavioral dysfunctions found in the hypothyroid animals were improved after a thyroid hormone replacement treatment. Thus, the present study suggests that impairment in the endocannabinoid system can underlay the hyperactive phenotype associated with hypothyroidism.