Insulin and cellular stressors both activate p38 MAPK. Insulin protects cardiac tissue in a p38 MAPK-dependent manner. Paradoxically, inhibiting p38 MAPK is also protective. Hsp27 phosphorylation is regulated by p38 MAPK. Insulin was tested in H9c2 cardiomyocytes subjected to media exchange, 6 hours of oxygen-glucose deprivation, and reoxygenation. Insulin suppressed stress-induced phosphorylation of Hsp27 due to media-exchange or oxygen-glucose deprivation. Surprisingly, insulin increased Hsp27 phosphorylation during reoxygenation. Insulin also reduced total p38 MAPK levels. Insulin before oxygen-glucose deprivation prevented both localization of Hsp27 to the nucleus and localization of phospho-p38 MAPK to the cytoplasm. Insulin during oxygen-glucose deprivation caused the localization of phospho-p38 MAPK in the cytoplasm, but did not increase Hsp27 phosphorylation until reoxygenation. In conclusion, insulin may protect before oxygen-glucose deprivation by redirecting phospho-p38 MAPK to the nucleus away from damaging pathways in the cytoplasm and protects during oxygen-glucose deprivation by priming phospho-p38 MAPK to phosphorylate Hsp27. / Insulin was used on a model on H9c2 myotubes to determine the effect of oxygen-glucose deprivation and reoxygenation on the localization and phosphorylation of Hsp27 and p38 MAPK

Spinal muscle atrophy (SMA) is an autosomal recessive neurodegenerative disease which is characterized by the loss of α motor neurons from the anterior horn of the spinal cord, resulting in progressive muscle atrophy. The loss of functional Survival motor neuron (SMN) protein due to mutations or deletion in the SMN1 gene is the cause of SMA. A potential treatment strategy for SMA is to upregulate levels of the SMN protein originating from the copy gene SMN2 which can compensate in part for the absence of the functional SMN1 gene. I have shown a novel therapeutic strategy for SMA treatment through the activation of the p38 pathway by the bacterial antibiotic anisomycin which stabilizes and increases SMN mRNA levels in vitro. Activation of the p38 pathway by anisomycin leads to cytoplasmic accumulation of HuR protein which binds to the 3’UTR of SMN transcript resulting in increased SMN levels. This opens up a novel potential therapeutic strategy for SMA. I have also identified and demonstrated a significant induction of SMN protein levels in vitro and in vivo upon treatment with FDA approved drug celecoxib, which also activates the p38 pathway. Celecoxib mitigates disease severity along with increasing the lifespan of SMA mice. Sodium valproate, trichostatin A and aclarubicin, all agents which effectively enhance SMN2 expression, have been recently shown to activate STAT5 in SMA-like mouse embryonic fibroblasts and human SMN2-transfected NSC34 cells. Given that prolactin is also known to activate the STAT5 signalling pathway, can cross blood brain barrier and is FDA approved, we elected to assess its impact on SMN levels. In this manner, I have demonstrated a significant induction in SMN mRNA and protein levels in neuronal NT2 and MN-1 cells upon treatment with prolactin. I have also demonstrated that activation of the STAT5 pathway by prolactin is necessary for this transcriptional upregulation of the SMN gene. I have found that prolactin treatment induces SMN expression in brain and spinal cord samples and that it ameliorates the disease phenotype, improving motor neuron function and increasing survival in the SMA mouse model. Presently there is no cure for SMA. This study will help in the identification and characterization of potential therapeutic compounds for the treatment of SMA.

Spinal muscle atrophy (SMA) is an autosomal recessive neurodegenerative disease which is characterized by the loss of α motor neurons from the anterior horn of the spinal cord, resulting in progressive muscle atrophy. The loss of functional Survival motor neuron (SMN) protein due to mutations or deletion in the SMN1 gene is the cause of SMA. A potential treatment strategy for SMA is to upregulate levels of the SMN protein originating from the copy gene SMN2 which can compensate in part for the absence of the functional SMN1 gene. I have shown a novel therapeutic strategy for SMA treatment through the activation of the p38 pathway by the bacterial antibiotic anisomycin which stabilizes and increases SMN mRNA levels in vitro. Activation of the p38 pathway by anisomycin leads to cytoplasmic accumulation of HuR protein which binds to the 3’UTR of SMN transcript resulting in increased SMN levels. This opens up a novel potential therapeutic strategy for SMA. I have also identified and demonstrated a significant induction of SMN protein levels in vitro and in vivo upon treatment with FDA approved drug celecoxib, which also activates the p38 pathway. Celecoxib mitigates disease severity along with increasing the lifespan of SMA mice. Sodium valproate, trichostatin A and aclarubicin, all agents which effectively enhance SMN2 expression, have been recently shown to activate STAT5 in SMA-like mouse embryonic fibroblasts and human SMN2-transfected NSC34 cells. Given that prolactin is also known to activate the STAT5 signalling pathway, can cross blood brain barrier and is FDA approved, we elected to assess its impact on SMN levels. In this manner, I have demonstrated a significant induction in SMN mRNA and protein levels in neuronal NT2 and MN-1 cells upon treatment with prolactin. I have also demonstrated that activation of the STAT5 pathway by prolactin is necessary for this transcriptional upregulation of the SMN gene. I have found that prolactin treatment induces SMN expression in brain and spinal cord samples and that it ameliorates the disease phenotype, improving motor neuron function and increasing survival in the SMA mouse model. Presently there is no cure for SMA. This study will help in the identification and characterization of potential therapeutic compounds for the treatment of SMA.

Palmitate (PA), one of the most prevalent saturated fatty acids, causes myocardial dysfunction. However, the mechanisms by which PA induces cell apoptosis and autophagy remain to be elucidated. We showed that autophagy was induced in an mTORC1-dependent way and played a protective role against PA-induced apoptosis, which was verified by pretreatment with 3-methyladenine (3MA) and rapamycin. However, p62 began to accumulate after 18 h treatment with PA, suggesting prolonged exposure to PA lead to an impairment of autophagic flux. PA enhanced ROS production as well as activated p38-mitogen-activated protein kinase (p38 MAPK) and c-jun NH2 terminal kinases (JNKs). The antioxidant N-Acety-L-Cysteine (NAC) was found to attenuate the JNK and p38 MAPK activation with a concomitant reduction of PA-induced autophagy and apoptosis. Furthermore, both JNK and p38 MAPK inhibitors were shown to directly abrogate caspase 7 cleavage as well as the conversion of LC3BI to LC3BII. Thus, we demonstrate that PA stimulates autophagy and apoptosis via ROS-dependent JNK and p38 MAPK pathways.

Valproic acid (VPA), a widely prescribed drug for seizures and bipolar disorder, induces apoptosis in microglia, but the underlying mechanism by which microglia apoptosis in response to VPA is not yet known. In this study, we found that the mitochondrial pathway played an important role in VPA-induced apoptosis in both BV-2 microglia and mouse primary microglial cells. In addition, VPA increased the level of phospho-p38 mitogen-activated protein kinase (MAPK), but had no effects on phospho-ERK and phospho-JNK MAPKs. Moreover, p38 inhibitor SB203580 strongly inhibited VPA-induced apoptosis and caspase-3 activation. Taken together, our results clearly demonstrated that VPA could induce apoptosis of microglia via p38 MAPK and mitochondrial apoptosis pathway.

Cardiac fibroblasts play an important role in myocardial remodeling by proliferating, differentiating, and secreting extracellular matrix proteins. Estrogen has been reported to have a number of cardioprotective properties. However, it is unclear whether estrogen affects cardiac fibroblast differentiation. The purpose of the present study was to investigate the effect of estrogen on angiotensin II-induced cardiac fibroblast proliferation and differentiation. Cardiac fibroblasts were stimulated with angiotensin II (1 μM) in the presence or absence of 17β-estradiol (100 nM). Pretreatment of cardiac fibroblasts with 17β-estradiol significantly inhibited angiotensin II-induced cardiac fibroblast proliferation and differentiation (indicated by a reduction in alpha-smooth muscle actin (α-SMA) expression) by 25% and 20%. Pretreatment of 17β-estradiol significantly reduced angiotensin II-increased levels of phospho-p38 mitogen-activated protein kinase (MAPK) by 40% and nuclear factor-κB (NF-κB) binding activity in cardiac fibroblasts by 55%. Our data suggests estrogen could have an anti-fibrotic effect through limiting cardiac fibroblast proliferation and differentiation, which are the critical steps in the pathogenesis of cardiac fibrosis.

京都大学 / 0048 / 新制・論文博士 / 博士(医学) / 乙第13206号 / 論医博第2160号 / 新制||医||1031(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 木村 剛, 教授 岩田 想, 教授 秋山 芳展 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM

No description available.

No / Cryptolepis sanguinolenta and its bioactive alkaloid, cryptolepine have shown anti-inflammatory activity. However, the underlying mechanism of anti-inflammatory action in neuronal cells has not been investigated. In the present study we evaluated an extract of C. sanguinolenta (CSE) and cryptolepine (CAS) on neuroinflammation induced with IL-1β in SK-N-SH neuroblastoma cells. We then attempted to elucidate the mechanisms underlying the anti-neuroinflammatory effects of CAS in SK-N-SH cells. Cells were stimulated with 10 U/ml of IL-1β in the presence or absence of different concentrations of CSE (25–200 μg/ml) and CAS (2.5–20 μM). After 24 h incubation, culture media were collected to measure the production of PGE2 and the pro-inflammatory cytokines (TNFα and IL-6). Protein and gene expressions of cyclooxygenase (COX-2) and microsomal prostaglandin synthase-1 (mPGES-1) were studied by immunoblotting and qPCR, respectively. CSE produced significant (p < 0.05) inhibition of TNFα, IL-6 and PGE2 production in SK-N-SH cells. Studies on CAS showed significant and dose-dependent inhibition of TNFα, IL-6 and PGE2 production in IL-1β-stimulated cells without affecting viability. Pre-treatment with CAS (10 and 20 μM) was also found to inhibit IL-1β-induced protein and gene expressions of COX-2 and mPGES-1. Further studies to determine the mechanism of action of CAS showed inhibition of NF-κBp65 nuclear translocation, but not IκB phosphorylation. At 10 and 20 μM, CAS inhibited IL-1β-induced phosphorylation of p38 MAPK. Studies on the downstream substrate of p38, MAPK-activated protein kinase 2 (MAPKAPK2) showed that CAS produced significant (p < 0.05) and dose dependent inhibition of MAPKAPK2 phosphorylation in IL-1β-stimulated SK-N-SH cells. This study clearly shows that cryptolepine (CAS) inhibits neuroinflammation through mechanisms involving inhibition of COX-2 and mPGES-1. It is suggested that these actions are probably mediated through NF-κB and p38 signalling.

O monóxido de carbono (CO) tem um importante papel na fisiologia animal incluindo plasticidade sináptica, processos de memória e aprendizagem, inflamação e liberação de neuropeptídios hipotalâmicos. Recentemente tem sido demonstrado que a liberação de vasopressina (AVP) e ocitocina (OT) em resposta a alterações no balanço hidromineral pode ser modulada por esse neuromodulador gasoso, contudo, os mecanismos pelos quais essa modulação ocorre ainda não foram elucidados. Nesse sentido, nós mapeamos possíveis alvos intracelulares do CO pelos quais esse gás poderia afetar as respostas neuroendócrinas tais como as propriedades passivas de membrana de neurônios magnocelulares do núcleo supraóptico (SON), via de sinalização da p38 MAPK, sistema óxido nítrico (NO)/óxido nítrico sintase (NOS), participação de astrócitos hipotalâmicos e a resposta antioxidante à diferentes condições de hidratação: euhidratação, 24 e 48 horas de privação hídrica. Nós observamos que a inibição da formação central de CO reduziu o aumento das concentrações plasmáticas de AVP e OT induzido pela privação hídrica, bem como inibiu a atividade NOS nos grupos hidratado e desidratado por 48 horas (PH 48); enquanto a razãoe p-p38 MAPK/p38 MAPK ratio foi aumentada pela doação central de CO em todas as condições de hidratação analisadas. Além do mais, nós demonstramos a expressão de HO-1, p38 MAPK e p-p38 MAPK em astrócitos hipotalâmicos. Em relação à resposta antioxidade, observamos que camundongos silenciados para Nrf2 no SON tem a resposta à desidratação prejudicada. Esses dados indicam o papel do CO como uma molécula neuromodulatória nas respostas neuroendócrinas à desidratação onde pode exercer sua função via resposta antioxidante em tempo mais curto de restrição hídrica e via sistema do NO em tempo mais prolongado / Carbon monoxide plays important roles in animal physiology including synaptic plasticity, learning and memory processes, inflammation and hypothalamic neuropeptide release. Recently it has been demonstrated that the AVP and OT release in response to changes in hydromineral balance can be modulated by this gaseous neuromodulator; however, the mechanisms by which this modulation occurs need to be elucidated. In order to answer this questioning, we evaluated the CO effect on neuroendocrine responses, SON magnocellular neurons passive membrane properties, p38 MAPK signaling, NO/NOS system and astrocytes participation in rats during control or 24/48 WD conditions. We observed that CO formation inhibition reduced the water deprivation-induced increase in plasma AVP and OT concentration and NOS activity in basal and 48 WD groups; while p-p38 MAPK/p38 MAPK ratio was increased by central CO donation in both euhydrated and dehydrated conditions. Furthermore, we demonstrated HO-1, p38 MAPK and p-p38 MAPK expression in MBH astrocytes. These data indicate the CO role as neuromodulatory molecule in neuroendocrine responses to dehydration where it might play its biological functions through p38 MAPK phosphorylation and NOS activity in a water restriction longer period