Seung Hwa Park

Konkuk University, Sŏul, Seoul, South Korea

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Publications (34)102.5 Total impact

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    ABSTRACT: Preconception exposure to EtOH through the paternal route may affect neurobehavioral and developmental features of offspring. This study investigates the effects of paternal exposure to EtOH before conception on the hyperactivity, inattention, and impulsivity behavior of male offspring in mice. Sire mice were treated with EtOH in a concentration range approximating human binge drinking (0-4 g/kg/day EtOH) for 7 weeks and mated with untreated females mice to produce offspring. EtOH exposure to sire mice induced attention deficit hyperactivity disorder (ADHD)-like hyperactive, inattentive, and impulsive behaviors in offspring. As a mechanistic link, both protein and mRNA expression of dopamine transporter (DAT), a key determinant of ADHD-like phenotypes in experimental animals and humans, were significantly decreased by paternal EtOH exposure in cerebral cortex and striatum of offspring mice along with increased methylation of a CpG region of the DAT gene promoter. The increase in methylation of DAT gene promoter was also observed in the sperm of sire mice, suggesting germline changes in the epigenetic methylation signature of DAT gene by EtOH exposure. In addition, the expression of two key regulators of methylation-dependent epigenetic regulation of functional gene expression, namely, MeCP2 and DNMT1, was markedly decreased in offspring cortex and striatum sired by EtOH-exposed mice. These results suggest that preconceptional exposure to EtOH through the paternal route induces behavioral changes in offspring, possibly via epigenetic changes in gene expression, which is essential for the regulation of ADHD-like behaviors. © 2014 Wiley Periodicals, Inc.
    Journal of Neuroscience Research 02/2014; · 2.97 Impact Factor
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    ABSTRACT: Abnormal scarring results from the expression and composition of extracellular matrix molecules. The transcription and translation of collagens I and III, fibronectin, laminin, periostin, and tenascin are all increased in raised dermal scar tissue. However, human keloid development is not fully defined. In this study, we identified proteins expressed differentially between normal skin and keloid scar tissues and examined their function in keloid formation using fibroblasts. Skin specimens from normal volunteers and patients with keloids were obtained by skin biopsy. Whole proteins were isolated by two-dimensional electrophoresis, and differentially expressed proteins were identified by matrix-assisted laser desorption/ionization-time of flight/time of flight mass spectrometry. Protein function was determined by proliferation assay using annexin A2-overexpressing keloid fibroblasts. The expression of 11 protein spots was altered by at least 1.5-fold in patients with keloids than in normal volunteers. Of these proteins, annexin A2, a pre-serum amyloid P component, serum albumin precursor, and tryptase-I, were down-regulated in keloid tissue compared to normal skin. Collagen alpha 1(V) chain precursor, collagen alpha 1(I) chain precursor, ferritin light subunit, alpha 1(III) collagen, 6-phosphogluconolactonase, and calponin 2 were up-regulated. Diminished expression of annexin A2 was confirmed by immunoblotting and immunohistochemistry. Treatment with the recombinant human epidermal growth factor increased proliferation of keloid fibroblasts, which was more inhibited in annexin A2-overexpressing fibroblasts than in non-transfected control cells. These results imply that annexin A2 may participate in keloid formation by inhibiting keloid fibroblast proliferation. Therefore, it is concluded that annexin A2 may be a valuable therapeutic target for keloid lesions.
    Archives for Dermatological Research 01/2014; · 2.71 Impact Factor
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    ABSTRACT: Korean Red Ginseng (KRG) is an oriental herbal preparation obtained from Panax ginseng Meyer (Araliaceae). To expand our understanding of the action of KRG on central nervous system (CNS) function, we examined the effects of KRG on tissue plasminogen activator (tPA)/plasminogen activator inhibitor-1 (PAI-1) expression in rat primary astrocytes. KRG extract was treated in cultured rat primary astrocytes and neuron in a concentration range of 0.1 to 1.0 mg/mL and the expression of functional tPA/PAI-1 was examined by casein zymography, Western blot and reverse transcription-polymerase chain reaction. KRG extracts increased PAI-1 expression in rat primary astrocytes in a concentration dependent manner (0.1 to 1.0 mg/mL) without affecting the expression of tPA itself. Treatment of 1.0 mg/mL KRG increased PAI-1 protein expression in rat primary astrocytes to 319.3±65.9% as compared with control. The increased PAI-1 expression mediated the overall decrease in tPA activity in rat primary astrocytes. Due to the lack of PAI-1 expression in neuron, KRG did not affect tPA activity in neuron. KRG treatment induced a concentration dependent activation of PI3K, p38, ERK1/2, and JNK in rat primary astrocytes and treatment of PI3K or MAPK inhibitors such as LY294002, U0126, SB203580, and SP600125 (10 μM each), significantly inhibited 1.0 mg/mL KRG-induced expression of PAI- 1 and down-regulation of tPA activity in rat primary astrocytes. Furthermore, compound K but not other ginsenosides such as Rb1 and Rg1 induced PAI-1 expression. KRG-induced up-regulation of PAI-1 in astrocytes may play important role in the regulation of overall tPA activity in brain, which might underlie some of the beneficial effects of KRG on CNS such as neuroprotection in ischemia and brain damaging condition as well as prevention or recovery from addiction.
    Journal of ginseng research 10/2013; 37(4):401-12. · 2.26 Impact Factor
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    ABSTRACT: In-utero exposure to valproic acid (VPA) has been known as a potent inducer of autism spectrum disorder (ASD), not only in humans, but also in animals. In addition to the defects in communication and social interaction as well as repetitive behaviors, ASD patients usually suffer from gastrointestinal (GI) problems. However, the exact mechanism underlying these disorders is not known. In this study, we examined the gross GI tract structure and GI motility in a VPA animal model of ASD. On embryonic day 12 (E12), 4 pregnant Sprague-Dawley (SD) rats were subcutaneously injected with VPA (400 mg/kg) in the treatment group, and with phosphate buffered saline (PBS) in the control group; the resulting male offspring were analyzed at 4 weeks of age. VPA exposure decreased the thickness of tunica mucosa and tunica muscularis in the stomach and ileum. Other regions such as duodenum, jejunum, and colon did not show a significant difference. In high-resolution microscopic observation, atrophy of the parietal and chief cells in the stomach and absorptive cells in the ileum was observed. In addition, decreased staining of the epithelial cells was observed in the hematoxylin and eosin (H&E)-stained ileum section. Furthermore, decreased motility in GI tract was also observed in rat offspring prenatally exposed to VPA. However, the mechanism underlying GI tract defects in VPA animal model as well as the association between abnormal GI structure and function with ASD is yet to be clearly understood. Nevertheless, the results from the present study suggest that this VPA ASD model undergoes abnormal changes in the GI structure and function, which in turn could provide beneficial clues pertaining to the pathophysiological relevance of GI complications and ASD phenotypes.
    Toxicological research. 09/2013; 29(3):173-9.
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    ABSTRACT: Although the role of α-synuclein aggregation on Parkinson's disease is relatively well known, the physiological role and the regulatory mechanism governing the expression of α-synuclein are unclear yet. We recently reported that α-synuclein is expressed and secreted from cultured astrocytes. In this study, we investigated the effect of valproic acid (VPA), which has been suggested to provide neuroprotection by increasing α-synuclein in neuron, on α-synuclein expression in rat primary astrocytes. VPA concentrationdependently increased the protein expression level of α-synuclein in cultured rat primary astrocytes with concomitant increase in mRNA expression level. Likewise, the level of secreted α-synuclein was also increased by VPA. VPA increased the phosphorylation of Erk1/2 and JNK and pretreatment of a JNK inhibitor SP600125 prevented the VPA-induced increase in α-synuclein. Whether the increased α-synuclein in astrocytes is involved in the reported neuroprotective effects of VPA awaits further investigation.
    Biomolecules and Therapeutics 05/2013; 21(3):222-228. · 0.79 Impact Factor
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    ABSTRACT: Liver regeneration after liver damage caused by toxins and pathogens is critical for liver homeostasis. Retardation of liver proliferation was reported in hepatitis B virus (HBV) X protein (HBx)-transgenic mice. However, the underlying mechanism of the HBx-mediated disturbance of liver regenerationis unknown.We investigated the molecular mechanismof the inhibition of liver regeneration using liver cell lines and a mouse model. The mouse model of acute HBV infection was established by hydrodynamic injection of viral DNA.Liver regeneration after partial hepatectomy was significantly inhibited in the HBV DNA-treatedmice. Mechanism studies have revealed that the expression of urokinase-type plasminogen activator (uPA), which regulates the activation of hepatocyte growth factor (HGF), was significantly decreased in the liver tissues of HBV or HBx-expressing mice. The down-regulation of uPA was further confirmed using liver cell lines transiently or stably transfected with HBx and the HBV genome. HBx suppresseduPA expression through the epigenetic regulationof the uPA promoter in mice liver tissues and human liver cell lines. Expression of HBx strongly induced hyper-methylation of the uPA promoter byrecruiting DNA methyltransferase (DNMT) 3A2.Conclusions:Taken together,these resultssuggest that infection of HBV impairs liver regeneration throughthe epigenetic dysregulation of liver regeneration signals by HBx. (HEPATOLOGY 2013.).
    Hepatology 03/2013; · 12.00 Impact Factor
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    ABSTRACT: Prenatal exposure to alcohol has consistently been associated with adverse effects on neurodevelopment, which is collectively called fetal alcohol spectrum disorder (FASD). Increasing evidence suggest that prenatal exposure to alcohol increases the risk of developing attention deficit/hyperactivity disorder-like behavior in human. In this study, we investigated the behavioral effects of prenatal exposure to EtOH in offspring mice and rats focusing on hyperactivity and impulsivity. We also examined changes in dopamine transporter and MeCP2 expression, which may underlie as a key neurobiological and epigenetic determinant in FASD and hyperactive, inattentive and impulsive behaviors. Mouse or rat offspring born from dam exposed to alcohol during pregnancy (EtOH group) showed hyper locomotive activity, attention deficit and impulsivity. EtOH group also showed increased dopamine transporter and norepinephrine transporter level compared to control group in the prefrontal cortex and striatum. Prenatal exposure to EtOH also significantly decreased the expression of MeCP2 in both prefrontal cortex and striatum. These results suggest that prenatal exposure to EtOH induces hyperactive, inattentive and impulsive behaviors in rodent offspring that might be related to global epigenetic changes as well as aberration in catecholamine neurotransmitter transporter system.
    Neurochemical Research 01/2013; · 2.13 Impact Factor
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    ABSTRACT: Presently, few treatments for spinal cord injury (SCI) are available and none have facilitated neural regeneration and/or significant functional improvement. Agmatine (Agm), a guanidinium compound formed from decarboxylation of L-arginine by arginine decarboxylase, is a neurotransmitter/neuromodulator and been reported to exert neuroprotective effects in central nervous system injury models including SCI. The purpose of this study was to demonstrate the multifaceted effects of Agm on functional recovery and remyelinating events following SCI. Compression SCI in mice was produced by placing a 15 g/mm(2) weight for 1 min at thoracic vertebra (Th) 9 segment. Mice that received an intraperitoneal (i.p.) injection of Agm (100 mg/kg/day) within 1 hour after SCI until 35 days showed improvement in locomotor recovery and bladder function. Emphasis was made on the analysis of remyelination events, neuronal cell preservation and ablation of glial scar area following SCI. Agm treatment significantly inhibited the demyelination events, neuronal loss and glial scar around the lesion site. In light of recent findings that expressions of bone morphogenetic proteins (BMPs) are modulated in the neuronal and glial cell population after SCI, we hypothesized whether Agm could modulate BMP- 2/4/7 expressions in neurons, astrocytes, oligodendrocytes and play key role in promoting the neuronal and glial cell survival in the injured spinal cord. The results from computer assisted stereological toolbox analysis (CAST) demonstrate that Agm treatment dramatically increased BMP- 2/7 expressions in neurons and oligodendrocytes. On the other hand, BMP- 4 expressions were significantly decreased in astrocytes and oligodendrocytes around the lesion site. Together, our results reveal that Agm treatment improved neurological and histological outcomes, induced oligodendrogenesis, protected neurons, and decreased glial scar formation through modulating the BMP- 2/4/7 expressions following SCI.
    PLoS ONE 01/2013; 8(1):e53911. · 3.53 Impact Factor
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    ABSTRACT: J. Neurochem. (2012) 123, 226-238. ABSTRACT: Fragile X syndrome (FXS), the most common single genetic cause of mental retardation and autistic spectrum disease, occurs when FMR1 gene is mutated. FMR1 encodes fragile X mental retardation protein (FMRP) which regulates translation of mRNAs playing important roles in the development of neurons as well as formation and maintenance of synapses. To examine whether FMRP regulates cell viability, we induced apoptosis in rat primary cortical neurons with glutamate in vitro and with middle cerebral artery occlusion (MCAO) in striatal neurons in vivo. Both conditions elicited a rapid, but transient FMRP expression in neurons. This up-regulated FMRP expression was abolished by pre-treatment with PI3K and Protein Kinase B (Akt) inhibitors: LY294002, Akt inhibitor IV, and VIII. Reduced FMRP expression in vitro or in vivo using small hairpin Fmr1 virus exacerbated cell death by glutamate or MCAO, presumably via hypophosphorylation of Akt and reduced expression of B-cell lymphoma-extra large (Bcl-xL). However, over-expression of FMRP using enhanced green fluorescent protein (eGFP)-FMRP constructs alleviated cell death, increased Akt activity, and enhanced Bcl-xL production. The pro-survival role of Akt-dependent up-regulation of FMRP in glutamate-stimulated cultured neuron as well as in ischemic brain may have a clinical importance in FXS as well as in neurodegenerative disorders and traumatic brain injury.
    Journal of Neurochemistry 07/2012; 123(2):226-238. · 3.97 Impact Factor
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    ABSTRACT: Background: Cancer is one of the highly virulent diseases known to humankind with a high mortality rate. Breast cancer is the most common cancer in women worldwide. Sorghum is a principal cereal food in many parts of the world, and is critical in folk medicine of Asia and Africa. In the present study, we analyzed the effects of HSE in metastatic breast cancer. Methodology/Principal Findings: Preliminary studies conducted on MDA-MB 231 and MCF-7 xenograft models showed tumor growth suppression by HSE. Western blotting studies conducted both in vivo and in vitro to check the effect of HSE in Jak/STAT pathways. Anti-metastatic effects of HSE were confirmed using both MDA-MB 231 and MCF-7 metastatic animal models. These studies showed that HSE can modulate Jak/STAT pathways, and it hindered the STAT5b/IGF-1R and STAT3/ VEGF pathways not only by down-regulating the expression of these signal molecules and but also by preventing their phosphorylation. The expression of angiogenic factors like VEGF, VEGF-R2 and cell cycle regulators like cyclin D, cyclin E, and pRb were found down-regulated by HSE. In addition, it also targets Brk, p53, and HIF-1a for anti-cancer effects. HSE induced G1 phase arrest and migration inhibition in MDA-MB 231 cells. The metastasis of breast cancer to the lungs also found blocked by HSE in the metastatic animal model. Conclusions/Significance: Usage of HS as a dietary supplement is an inexpensive natural cancer therapy, without any side effects. We strongly recommend the use of HS as an edible therapeutic agent as it possesses tumor suppression, migration inhibition, and anti-metastatic effects on breast cancer.
    PLoS ONE 07/2012; · 3.53 Impact Factor
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    ABSTRACT: The nonobese diabetic (NOD) mouse is a classical animal model for autoimmune type 1 diabetes (T1D), closely mimicking features of human T1D. Thus, the NOD mouse presents an opportunity to test the effectiveness of induced pluripotent stem cells (iPSCs) as a therapeutic modality for T1D. Here, we demonstrate a proof of concept for cellular therapy using NOD mouse-derived iPSCs (NOD-iPSCs). We generated iPSCs from NOD mouse embryonic fibroblasts or NOD mouse pancreas-derived epithelial cells (NPEs), and applied directed differentiation protocols to differentiate the NOD-iPSCs toward functional pancreatic beta cells. Finally, we investigated whether the NPE-iPSC-derived insulin-producing cells could normalize hyperglycemia in transplanted diabetic mice. The NOD-iPSCs showed typical embryonic stem cell-like characteristics such as expression of markers for pluripotency, in vitro differentiation, teratoma formation, and generation of chimeric mice. We developed a method for stepwise differentiation of NOD-iPSCs into insulin-producing cells, and found that NPE-iPSCs differentiate more readily into insulin-producing cells. The differentiated NPE-iPSCs expressed diverse pancreatic beta cell markers and released insulin in response to glucose and KCl stimulation. Transplantation of the differentiated NPE-iPSCs into diabetic mice resulted in kidney engraftment. The engrafted cells responded to glucose by secreting insulin, thereby normalizing blood glucose levels. We propose that NOD-iPSCs will provide a useful tool for investigating genetic susceptibility to autoimmune diseases and generating a cellular interaction model of T1D, paving the way for the potential application of patient-derived iPSCs in autologous beta cell transplantation for treating diabetes.
    Stem cells and development 04/2012; 21(14):2642-55. · 4.15 Impact Factor
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    ABSTRACT: Bax Inhibitor-1 (BI-1) is an evolutionally conserved apoptotic suppressor and belongs to the BI-1 family of proteins, which contain BI-1-like transmembrane domains. As their cellular functions and regulatory mechanisms remain incompletely understood, we compared their anti-apoptotic properties. Forced expression of BI-1 resulted in the most effective suppression of stress-induced apoptosis, compared with other family members, together with significant extracellular signal-regulated kinase (ERK)1/2 activation. BI-1-mediated ERK1/2 activation led to the suppression of mitochondria-mediated reactive oxygen species (ROS) production. Involvement of the ERK signaling pathway in BI-1-induced anti-apoptotic effects was confirmed by knockdown studies with ERK- or BI-1-specific siRNA. Moreover, we produced transgenic (TG) mice overexpressing BI-1, and the relationship between ERK1/2 activation and the suppression of ROS production or apoptosis was confirmed in mouse embryonic fibroblast (MEF) cells derived from these mice. Interestingly, we found that BI-1 TG mice showed splenomegaly and abnormal megakaryopoiesis. Taken together, our results suggest that BI-1-induced ERK1/2 activation plays an important role in the modulation of intracellular ROS generation and apoptotic cell death and may also affect autoimmune response.
    Biochimica et Biophysica Acta 01/2012; 1823(4):876-88. · 4.66 Impact Factor
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    ABSTRACT: Oroxylin A is a flavone isolated from a medicinal herb reported to be effective in reducing the inflammatory and oxidative stresses. It also modulates the production of brain derived neurotrophic factor (BDNF) in cortical neurons by the transactivation of cAMP response element-binding protein (CREB). As a neurotrophin, BDNF plays roles in neuronal development, differentiation, synaptogenesis, and neural protection from the harmful stimuli. Adenosine A2A receptor colocalized with BDNF in brain and the functional interaction between A2A receptor stimulation and BDNF action has been suggested. In this study, we investigated the possibility that oroxylin A modulates BDNF production in cortical neuron through the regulation of A2A receptor system. As ex-pected, CGS21680 (A2A receptor agonist) induced BDNF expression and release, however, an antagonist, ZM241385, prevented oroxylin A-induced increase in BDNF production. Oroxylin A activated the PI3K-Akt-GSK-3β signaling pathway, which is inhibited by ZM241385 and the blockade of the signaling pathway abolished the increase in BDNF production. The physiological roles of oroxylin A-induced BDNF production were demonstrated by the increased neurite extension as well as synapse formation from neurons. Overall, oroxylin A might regulate BDNF production in cortical neuron through A2A receptor stimulation, which promotes cellular survival, synapse formation and neurite extension.
    Biomolecules and Therapeutics 01/2012; 20(1):27-35. · 0.79 Impact Factor
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    ABSTRACT: As a member of neurotrophin family, brain derived neurotrophic factor (BDNF) plays critical roles in neuronal development, differentiation, synaptogenesis, and neural protection from the harmful stimuli. There have been reported that adenosine A2(A) receptor subtype is widely distributed in the brain regions, such as hippocampus, striatum, and cortex. Adenosine A2(A) receptor is colocalized with BDNF in brain regions and the functional interaction between A2(A) receptor stimulation and BDNF action has been suggested. In this study, we investigated the possibility that the activation of A2(A) receptor modulates BDNF production in rat primary cortical neuron. CGS21680, an adenosine A2(A) receptor agonist, induced BDNF expression and release. An antagonist against A2(A) receptor, ZM241385, prevented CGS21680-induced increase in BDNF production. A2(A) receptor stimulation induced the activation of Akt-GSK-3β signaling pathway and the blockade of the signaling pathway with specific inhibitors abolished the increase in BDNF production, possibly via modulation of ERK1/2-CREB pathway. The physiological roles of A2(A) receptor-induced BDNF production was demonstrated by the protection of neurons from the excitotoxicity and increased neurite extension as well as synapse formation from immature and mature neurons. Taken together, activation of A2(A) receptor regulates BDNF production in rat cortical neuron, which provides neuro-protective action.
    Neurochemical Research 07/2011; 36(12):2259-69. · 2.13 Impact Factor
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    ABSTRACT: Induced pluripotent stem (iPS) cells have been generated from various somatic cells; however, a major restriction of the technology is the use of potentially harmful genome-integrating viral DNAs. Here, without a viral vector, we generated iPS cells from fibroblasts using a non-viral magnetic nanoparticle-based transfection method that employs biodegradable cationic polymer PEI-coated super paramagnetic nanoparticles (NP). Our findings support the possible use of transient expression of iPS genes in somatic cells by magnet-based nanofection for efficient generation of iPS cells. Results of dynamic light scattering (DLS) analysis and TEM analyses demonstrated efficient conjugation of NP with iPS genes. After transfection, nanofection-mediated iPS cells showed ES cell-like characteristics, including expression of endogenous pluripotency genes, differentiation of three germ layer lineages, and formation of teratomas. Our results demonstrate that magnet-based nanofection may provide a safe method for use in generation of virus-free and exogenous DNA-free iPS cells, which will be crucial for future clinical applications in the field of regenerative medicine.
    Biomaterials 06/2011; 32(28):6683-91. · 8.31 Impact Factor
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    ABSTRACT: In the current investigation, the status of the septo-hippocampal cholinergic pathway and hippocampal mitogen-activated protein kinase (MAPK) signaling was examined in male Wistar rats with chronic cerebral hypoperfusion, which showed cognitive deficits based on assessment on a version of the Morris water maze. Chronic cerebral hypoperfusion was induced by bilateral common artery occlusion and maintained for 12 weeks until behavioral testing. Chronic cerebral hypoperfusion was shown to induce memory impairments and microglial activation in regions of white matter, including the fimbria of hippocampus. Choline acetyltransferase expression of the basal forebrain and expression of hippocampal MAPKs was decreased in rats with BCCAo compared to control rats. The results of this study suggest that cognitive decline induced by chronic cerebral hypoperfusion could be related to dysfunction of the basal forebrain cholinergic system and reduction of hippocampal MAPK activities.
    Experimental neurobiology. 06/2011; 20(2):92-9.
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    ABSTRACT: Intended to investigate whether agmatine treatment reduces collagen scar area in mice subjected to spinal cord injury (SCI). The purpose of the present study is to demonstrate the protective effect of agmatine on complete transection SCI mice. SUMMARY OF BACK GROUND DATA: The deposition of collagen that occurs at the lesion site, during the SCI, was well known. Agmatine has been reported to exert neuroprotective effect in various stress models including central nervous system injuries. In the present investigation, we hypothesized that agmatine treatment could rescue the mice subjected to SCI. Complete SCI was made at the T9 level. Agmatine was dissolved in normal saline (100 mg/kg, Sigma, St. Louis, MO) and given intraperitoneally 5 minutes after complete transection daily for 4 weeks (agmatine-treated mice, n = 30). Controls received normal saline in the same manner (experimental control, n = 30). Surface righting reflex test, expression of bone morphogenetic protein-7 (BMP-7), TGFβ-2 (transforming growth factor β-2), and collagen scar area were measured and the results were compared with Mann-Whitney U test using SAS. Agmatine treatment improved the surface righting reflex of mice at 4 weeks after SCI (P = 0.030). The collagen scar, physical barrier to axon regeneration, was noticeably diminished by agmatine treatment at 4 weeks after SCI (P = 0.001). The expression of BMP-7, which is considered both neuroprotective and neuroregenerative, was increased in agmatine treatment group compared with experimental control group in the early stages after SCI (P = 0.015 at 1 day after SCI; P = 0.010 at 3 days; P = 0.035 at 1 week; P = 0.826 at 2 weeks). The expression of TGFβ-2 correlated with the deposition of the collagen matrix at the lesion site was decreased with agmatine treatment at 1 and 2 weeks after SCI (P = 0.001 at 1 week; P = 0.002 at 2 weeks). Survival rate was found to be higher in agmatine treatment group than in the experimental control group for 4 weeks after SCI (P = 0.076). These results suggest that agmatine treatment could support neuroregeneration by reducing the collagen scar area through decreasing the expression of TGFβ-2 and increasing the expression of BMP-7 after SCI. Especially, the improved surface righting reflex of agmatine-treated group proposes that agmatine treatment have the potency to facilitate functional recovery after SCI. However, the drug (agmatine) warrants further investigation in higher mammals.
    Spine 02/2011; 36(25):2130-8. · 2.16 Impact Factor
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    ABSTRACT: Hepatitis B virus (HBV) infection is one of the major causes of hepatocellular carcinoma (HCC) development. Hepatitis B virus X protein (HBx) is known to play a key role in the development of hepatocellular carcinoma (HCC). Several cellular proteins have been reported to be over-expressed in HBV-associated HCC tissues, but their role in the HBV-mediated oncogenesis remains largely unknown. Here, we explored the effect of the over-expressed cellular protein, a ribosomal protein S3a (RPS3a), on the HBx-induced NF-κB signaling as a critical step for HCC development. The enhancement of HBx-induced NF-κB signaling by RPS3a was investigated by its ability to translocate NF-κB (p65) into the nucleus and the knock-down analysis of RPS3a. Notably, further study revealed that the enhancement of NF-κB by RPS3a is mediated by its novel chaperoning activity toward physiological HBx. The over-expression of RPS3a significantly increased the solubility of highly aggregation-prone HBx. This chaperoning function of RPS3a for HBx is closely correlated with the enhanced NF-κB activity by RPS3a. In addition, the mutational study of RPS3a showed that its N-terminal domain (1-50 amino acids) is important for the chaperoning function and interaction with HBx. The results suggest that RPS3a, via extra-ribosomal chaperoning function for HBx, contributes to virally induced oncogenesis by enhancing HBx-induced NF-κB signaling pathway.
    PLoS ONE 01/2011; 6(8):e22258. · 3.53 Impact Factor
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    ABSTRACT: Recent studies indicate that Toll-like receptors (TLRs), originally identified as infectious agent receptors, also mediate sterile inflammatory responses during tissue damage. In this study, we investigated the role of TLR2 in excitotoxic hippocampal cell death using TLR2 knock-out (KO) mice. TLR2 expression was up-regulated in microglia in the ipsilateral hippocampus of kainic acid (KA)-injected mice. KA-mediated hippocampal cell death was significantly reduced in TLR2 KO mice compared with wild-type (WT) mice. Similarly, KA-induced glial activation and proinflammatory gene expression in the hippocampus were compromised in TLR2 KO mice. In addition, neurons in organotypic hippocampal slice cultures (OHSCs) from TLR2 KO mouse brains were less susceptible to KA excitotoxicity than WT OHSCs. This protection is partly attributed to decreased expression of proinflammatory genes, such as TNF-α and IL-1β in TLR2 KO mice OHSCs. These data demonstrate conclusively that TLR2 signaling in microglia contributes to KA-mediated innate immune responses and hippocampal excitotoxicity.
    Journal of Biological Chemistry 12/2010; 285(50):39447-39457. · 4.65 Impact Factor
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    ABSTRACT: Recent studies indicate that Toll-like receptors (TLRs), originally identified as infectious agent receptors, also mediate sterile inflammatory responses during tissue damage. In this study, we investigated the role of TLR2 in excitotoxic hippocampal cell death using TLR2 knock-out (KO) mice. TLR2 expression was up-regulated in microglia in the ipsilateral hippocampus of kainic acid (KA)-injected mice. KA-mediated hippocampal cell death was significantly reduced in TLR2 KO mice compared with wild-type (WT) mice. Similarly, KA-induced glial activation and proinflammatory gene expression in the hippocampus were compromised in TLR2 KO mice. In addition, neurons in organotypic hippocampal slice cultures (OHSCs) from TLR2 KO mouse brains were less susceptible to KA excitotoxicity than WT OHSCs. This protection is partly attributed to decreased expression of proinflammatory genes, such as TNF-α and IL-1β in TLR2 KO mice OHSCs. These data demonstrate conclusively that TLR2 signaling in microglia contributes to KA-mediated innate immune responses and hippocampal excitotoxicity.
    Journal of Biological Chemistry 10/2010; 285(50):39447-57. · 4.65 Impact Factor

Publication Stats

224 Citations
102.50 Total Impact Points

Institutions

  • 2007–2014
    • Konkuk University
      • • Neuroscience Center
      • • Department of Animal Biotechnology
      • • School of Medicine
      Sŏul, Seoul, South Korea
  • 2011–2012
    • Seoul National University
      • Research Institute of Pharmaceutical Sciences
      Sŏul, Seoul, South Korea
    • Konkuk University Medical Center
      Changnyeong, South Gyeongsang, South Korea
  • 2010
    • Sahmyook University
      Sŏul, Seoul, South Korea