Language：Japanese   Publisher：(公社)日本生化学会  

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DOI： 10.4172/2155-9538.1000e128

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Language：Japanese   Publisher：(公社)日本生化学会  

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Language：Japanese   Publisher：(公社)日本生化学会  

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Language：Japanese   Publisher：(公社)日本生化学会  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER IRELAND LTD  

Histone deacetylase (HDAC) inhibitors induce histone acetylation and gene expression by changing local chromatin structures. They can thereby influence various cells to proliferate or differentiate. It has been reported that trichostatin A (TSA) or valproic acid (VPA) can induce the neuronal differentiation of mouse embryonic neural stem cells and rat cerebellar granule cells. It is unclear however which gene is responsible for the neuronal differentiation induced by HDAC inhibitors. In this study, we investigated the contribution of immediate early gene (IEG) nur77 to the neuronal differentiation induced by TSA. We report that TSA induces neurite outgrowth in PC12 cells, and C646, an inhibitor of HAT (histone acetyl transferase) (p300), prevents TSA-induced neurite formation. The acetylation of the Lys14 residue of histone H3, and mRNA and protein expression of nur77 gene were found to be stimulated after treatment with TSA, but not in the presence of C646. A knock-down of nur77 inhibits the neurite outgrowth induced by TSA. Furthermore, the ectopic expression of nur77 significantly elicits neurite formation in PC12 cells. These results suggest that the expression of nur77, which is up-regulated via the TSA-induced acetylation of Lys14 on histone H3, is essential for the neuronal differentiation in TSA-induced PC12 cells.

DOI： 10.1016/j.neures.2014.07.009

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Language：Japanese   Publisher：(公社)日本生化学会  

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Language：Japanese   Publisher：(公社)日本生化学会  

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Language：Japanese   Publisher：(公社)日本生化学会  

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Language：Japanese   Publisher：(公社)日本生化学会  

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Language：Japanese   Publisher：(公社)日本生化学会  

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Language：Japanese   Publisher：(公社)日本生化学会  

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Language：Japanese   Publisher：(公社)日本生化学会  

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Language：English   Publisher：OXFORD UNIV PRESS  

Recent reports have indicated that some low-molecular-weight compounds mimic neurotrophic factors inducing neurite outgrowth and neuroprotection. Carnosic acid (CA) promotes neurite outgrowth through the activation of Nrf2 in PC12 cells. CA also protects neurons via the keap/Nrf2 transcriptional pathway from oxidative stress. Forskolin-induced neurite outgrowth is mediated by activation of the PKA signalling pathway and this PKA-mediated neurite outgrowth is achieved by the expression of nur77 in PC12 cells. In addition, forskolin at its low concentration is closely related to the cAMP-induced protective function against L-DOPA-induced cytotoxicity in PC12 cells. A HDAC inhibitor trichostatin A (TSA) increases neurite length via p53 acetylation in rat cultured cerebellar granule neurons and in cerebral cortical neurons, and also protects neurons against glutathione depletion-induced oxidative stress. Recently, it was revealed that Nrf2 and p53 bind to CBP/p300 directly, and Nur77 is acetylated in vivo and in vitro by CBP/p300. Acetylation of Nrf2, p53 and Nur77 by CBP/p300 may constitute a novel similar regulatory mechanism for low-molecular-weight compounds with neurotrophic activities.

DOI： 10.1093/jb/mvr113

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Language：Japanese   Publisher：(公社)日本生化学会  

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Language：Japanese   Publisher：(公社)日本生化学会  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER/PLENUM PUBLISHERS  

Following endoplasmic reticulum (ER) stress, cerebral infarctions have been reported to involve an apoptotic process, including the activation of the caspase cascade. To confirm whether fragmented caspase-12, which is activated by cleavage and is detectable during ER stress, is also involved in embolic cerebral infarctions in rats, we adopted an autologous blood clot model for the analysis of cerebral infarctions. We performed experiments in rats with brain infarctions, which are closely related to embolic cerebral infarctions. We utilized a homologous blood clot, i.e., natural materials, to form the infarct area. Our findings reveal that caspase-12 is fragmented when infarct areas form in cerebral cortical neurons. Interestingly, we observed that these fragments translocated to the nuclei of not only cerebral cortical neurons but hippocampal neurons. We further found that glucose-regulated protein 78 (GRP78), a marker of ER stress, is up-regulated in both cerebral cortical and hippocampal neurons during cerebral infarction. This result suggests that the fragmentation of caspase-12 and the subsequent nuclear translocation of these fragments are involved in the brain infarction process in rats.

DOI： 10.1007/s10571-011-9687-0

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Language：English   Publishing type：Part of collection (book)   Publisher：ELSEVIER ACADEMIC PRESS INC  

Nerve growth factor (NGF) was first described by Rita Levi-Montalcini in the early 1960s from her studies of peripheral neurons. It has since been reported that NGF has the potential to elongate neurites or to prevent apoptosis via specific intracellular mechanisms. It has further been reported that as a component of these mechanisms, NGF binds to a specific receptor, TrkA, and thereby contributes to peripheral nerve cell functions or neuronal functions. It is noteworthy in this regard that pheochromocytoma 12 (PC12) cells express TrkA and respond to neurite outgrowth or anti-apoptotic signals by binding to NGF. Hence, PC12 cells have been used as an in vitro model system for the study of neuronal functions. It has been reported that endoplasmic reticulum (ER) stress is involved in neurodegenerative disorders, including Alzheimer's, Parkinson's, and Huntington's disease. The common link with regard to ER stress is that the neuronal cells die in these pathologies via specific intracellular mechanisms. This type of cell death, if it is apoptotic in nature, is termed ER stress-mediated apoptosis. In the process of ER stress-mediated apoptosis, the cleavage of pro-caspase-12 residing on the ER and the expression of glucose-regulated protein 78 (GRP78) can be observed. The expression of GRP78 protein is a characteristic of an unfolded protein response (UPR) via specific signal transduction pathways mediated by the unfolded protein response element (UPRE) in the upstream region of the grp78 gene so on. In ER stress-mediated apoptosis, a caspase cascade is also observed. To further clarify the mechanisms underlying ER stress-mediated apoptosis, a better understanding of the UPR is therefore important. In our current study, we describe a method for detecting gene induction via the UPR, focusing on GRP78 and caspase activities as the measurement end-points. The information generated by our method will accelerate our understanding of the pathophysiological processes leading to ER stress-mediated apoptosis.

DOI： 10.1016/B978-0-12-385114-7.00003-9

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

An elevated level of cyclic AMP (cAMP) within cells activates gene expression through the cAMP-PKA-CREB pathway. Among the CREB target genes, some immediate early genes exist that are responsive to cAMP including the nur77 and c-fos genes. Treatment with dibutyryl-cAMP (dbcAMP) as well as nerve growth factor (NGF) induces neurite outgrowth in PC12 cells. Here, we report that acetylation of histone H3 was gradually stimulated after treatment with dbcAMP in PC12 cells and peaked 1 h after treatment. As the result of reverse transcription-polymerase chain reaction (RT-PCR) and quantitative real-time PCR (qPCR) experiments, both nur77 and c-fos gene expression were found to have peak 1 h after treatment. Knock-down with siRNA against nur77 mRNA inhibited the neurite outgrowth induced by dbcAMP, whereas knock-down with siRNA against c-fos mRNA did not inhibit the dbcAMP-induced neurite outgrowth. A chromatin immunoprecipitation (ChIP) assay revealed that the nur77 gene was associated with the acetylated Lys14 of histone H3 after treatment with dbcAMP. However, the amount of c-fos gene associated with acetylated histone H3 was not changed after treatment with dbcAMP. These results suggest that the expression of nur77, which is essential for the neuronal differentiation induced by dbcAMP, is up-regulated via dbcAMP-induced acetylation of the Lys14 of histone H3 in PC12 cells.

DOI： 10.1093/jb/mvq036

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER IRELAND LTD  

The glucose analog 2-deoxy-D-glucose (2DG) depletes cells of glucose. Inhibition of glycosylation caused by glucose depletion induces endoplasmic reticulum (ER) stress with subsequent apoptosis. Glucose-regulated protein 78 (GRP78) is a molecular chaperone that acts within the ER. During ER stress, GRP78 expression is induced as part of the unfolded protein response (UPR). We found that nerve growth factor (NGF) prevented 2DG-triggered ER stress-mediated apoptosis, but not the induction of GRP78 expression, in PC12 cells. Surprisingly, GRP78 expression was further up-regulated when NGF was added to 2DG-treated PC12 cells. When a specific inhibitor of phosphatidylinositol 3-kinase (PI3-K), LY294002, was added to 2DG plus NGF-treated cells, both the effects of NGF on 2DG-induced apoptosis and GRP78 expression were significantly diminished. In addition, versipelostatin (VST), a specific inhibitor of GRP78 expression, and small interfering RNA (siRNA) against GRP78 mRNA also decreased both the effects of NGF on 2DG-induced apoptosis and GRP78 expression. RT-PCR and Western blot analyses revealed that enhanced production of nuclear p50 ATF6, but not spliced XBP1, mainly contributed to the NGF-induced enhancement of GRP78 expression in 2DG-treated cells. These results suggest that the NGF-activated PI3-K/Akt signaling pathway plays a protective role against ER stress-mediated apoptosis via enhanced expression of GRP78 in PC12 cells. (C) 2009 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

DOI： 10.1016/j.neures.2009.09.003

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE  

Persistent endoplasmic reticulum (ER) stress and impairment of the ubiquitin-proteasome system (UPS) cause neuronal cell death. However, the relationship between these two phenomena remains controversial. In our current study, we have utilized an expanded polyglutamine fusion Protein (polyQ81) expression system in PC12 cells to further examine the involvement of ER stress and UPS impairment in cell death. The expression of polyQ81-induced ER stress and cell death. PolyQ81 also induced the activation of c-Jun N-terminal kinase (JNK) and caspase-3 and an increase in polyubiquitin immunoreactivity, suggesting UPS impairment. ER stress was induced prior to the accumulation of polyubiquitinated proteins. Low doses of lactacystin had almost similar effects on cell viability and on the activation of JNK and caspase-3 between normal cells and polyQ81-expressing cells. These results suggest that ER stress mediates polyglutamine toxicity prior to UPS impairment during the initial stages of these toxic effects. (C) 2008 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.bbrc.2008.10.006

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

We previously reported that nicotine protected against tunicamycin (T(m))-induced ER stress-mediated apoptosis, but not thapsigargin (T(g))-induced apoptosis in PC12 cells. In the present study, we report that the expression of glucose-regulated protein 78 (GRP78) was suppressed by nicotine in Tm-treated PC12 cells. Interestingly, the GRP78 expression was not changed by nicotine in Tg-treated cells. Moreover, nicotine reduced the activation of caspase-12 in Tm-treated cells, but not in Tg-treated cells. These results suggest that nicotine prevented Tm-induced ER stress-mediated apoptosis by attenuating an early stage of Tm-induced ER stress. It was possible that the suppression of GRP78 expression by nicotine was achieved through the suppression of the Ire1-XBP1 and/or ATF6 pathways. We observed that nicotine suppressed the Tm-induced, but not Tg-induced, splicing of XBP1 mRNA, and also suppressed the Tm-induced, but not Tg-induced, production of cleaved ATF6 in PC12 cells. These results indicate that the suppression of Ire1-XBP1 and ATF6 pathways contributes to the suppression of GRP78 expression by nicotine in Tm-treated PC12 cells, suggesting that nicotine suppresses a common step upstream of both the Ire1-XBP1 and ATF6 pathways which are required for the expression of GRP78 during Tm-induced ER stress.

DOI： 10.1093/jb/mvn063

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER IRELAND LTD  

Endocrine disrupting chemicals (EDCs) induce estrogenic phenotypes in sexual organs and cells by chronic stimulation through binding to estrogen receptors. Although cell death may be induced instead of phenotypic change by EDCs in germ cells, the mechanism of the effect of EDCs in neuronal cells is still obscure. Here we report that p-nonylphenol, one of the EDCs, induced apoptosis with up-regulation of glucose-regulated protein 78 (GRP78) expression and activation of caspase-12, which are involved in endoplasmic reticulum (ER) stress specific phenomena, in NGF-treated neuronally differentiated PC12 cells. Moreover, we observed that p-nonylphenol increased the intracellular Ca2+ concentration and p-nonylphenol-induced apoptosis was prevented when BAPTA-AM, a membrane-permeable Ca2+ chelator, was added. Intriguingly, we also discovered that decreased phosphorylation of ERK1/2 was induced by p-nonylphenol in the presence of NGF, whereas p-nonylphenol alone did not induce phosphorylation of ERK1/2. These lines of evidence suggest that p-nonyl phenol can induce ER stress-mediated apoptosis via increased intracellular Ca2+ concentration, and can reduce ERK1/2 phosphorylation to attenuate the cell survival effect of NGF, in neuronally differentiated PC12 cells. (c) 2007 Elsevier Ireland Ltd. All rights reserved.

DOI： 10.1016/j.neulet.2007.11.058

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Kansai University Special Research Fund 20070401-20080331

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER  

New series historic deacetylase inhibitors comprising a hydroxamic acid or 2-aminobenzamide group as a zinc-chelating function were synthesized and evaluated for antiproliferative activities against a panel of human cancer cells. The 2-aminobenzamide series inhibitors generally had the potency in cell growth inhibitions comparable to that of MS-275. Among them, the compound having a (3,4-difluorobenzyl)(2-hydroxyethyl) amino group at one end and a 2-aminobenzamide group at the other of molecule showed the most promising profile as an anticancer drug candidate, since it had a comparatively low toxicity as did MS-275 against a normal fibroblast cell CCD-1059SK. Additionally, the derivative exhibited a high recovery in human plasma stability test. (c) 2006 Elsevier SAS. All rights reserved.

DOI： 10.1016/j.ejmech.2006.02.002

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER IRELAND LTD  

Although many kinds of nicotinic acetylcholine receptor (nAChR) subtypes have been reported in the neuronal tissues, subtype differences in the nAChR-mediated intracellular signaling remains obscure. Using nAChR agonists and antagonists, the involvement of nAChRs in extracellular signal-regulated protein kinase (ERK) phosphorylation in PC12h cells was investigated. Cytisine and nicotine induced the phosphorylation of ERKs in a dose-dependent manner, whereas RJR-2403 had no effect. Cytisine, but not RJR-2403, also induced phosphorylation of CREB. Mecamylamine, dextromethorphan and 18-methoxycoronaridine inhibited nicotine-induced ERK phosphorylation with much higher affinity than dihydro-beta-erythroidine and alpha-conotoxin MII. These results suggest the involvement of alpha 3 beta 4 nAChRs in ERK phosphorylation in PC12h cells. (C) 2005 Elsevier Ireland Ltd. All rights reserved.

DOI： 10.1016/j.neulet.2005.09.003

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER IRELAND LTD  

Tunicamycin, an inhibitor of the glycosylation of newly biosynthesized proteins, induces endoplasmic reticulum (ER) stress and subsequent apoptosis, and caspase family proteases are activated during the process of ER stress-mediated apoptosis. In the present study, we showed that thapsigargin (Th), an inhibitor of the sarcoplasmic/endoplasmic reticulum Ca2+ ATPase (SERCA), also induced ER stress-mediated apoptosis, and nerve growth factor (NGF) prevented the apoptosis in PC 12 cells. We also found that LY294002, an inhibitor of phosphatidylinositol 3-kinase (PI3-K), reduced the survival of cells treated with NGF for 24 It in the presence of Th. We discovered that the activities of caspase-3, -9 and -12 were increased time-dependently after the treatment with Th, and NGF suppressed the Th-triggered activation of caspase-3, -9 and -12. LY294002 diminished the effect of NGF on the inactivation of all these caspases. These results indicate that the NGF-induced PI3-K signaling pathway prevents Th-triggered ER stress-specific apoptosis via inhibition of caspase-mediated apoptotic signal. (C) 2005 Elsevier Ireland Ltd. All rights reserved.

DOI： 10.1016/j.neulet.2005.07.030

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

We purified the psychrophilic and thermolabile malate dehydrogenase to homogeneity from a novel psychrotolerant, Flavobacterium frigidimaris KUC-1, isolated from Antarctic seawater. The enzyme was a homotetramer with a molecular weight of about 123k and that of the subunit was about 32 k. The enzyme required NAD(P)(+) as a coenzyme and catalyzed the oxidation Of L-malate and the reduction of oxalacetate specifically. The reaction proceeded through an ordered bi-bi mechanism. The enzyme was highly susceptible to heat treatment, and the half-life time at 40 degrees C was estimated to be 3.0 min. The k(cat)/K-m (mu m(-1).s(-1)) values for L-malate and NAD(+) at 30 degrees C were 289 and 2,790, respectively. The enzyme showed pro-R stereospecificity for hydrogen transfer at the C4 position of the nicotinamide moiety of the coenzyme. The enzyme contained 311 amino acid residues and much lower numbers of proline and arginine residues than other malate dehydrogenases.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We have recently reported that the ASK1-p38 MAPK pathway has an important role in the low potassium (LK)-induced apoptosis of cultured cerebellar granule neurons. In the present study, we observed that ERK1/2 were significantly activated 6 h after a change of medium from HK (high potassium) to LK. In addition, U0126, a specific inhibitor of MEKs, remarkably prevented the apoptosis of cultured cerebellar granule neurons. Then, we examined the mechanism underlying the activation of ERK1/2 in the LK-induced apoptotic pathway. The addition of SB203580, an inhibitor of p38 MAPK, suppressed the increase in the phosphorylation of ERK1/2 after the change to LK medium. Furthermore, we found that the expression of a constitutively active mutant of ASK1, an upstream kinase of p38 MAPK, enhanced the phosphorylation of ERK1/2. These results suggest that ERK1/2 play a crucial role in LK-induced apoptosis of cultured cerebellar granule neurons and that the LK-stimulated activation of ERK1/2 is regulated by the ASK1-p38 MAPK pathway. (c) 2005 Elsevier B.V All rights reserved.

DOI： 10.1016/j.brainres.2005.01.041

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Brain-derived neurotrophic factor (BDNF), one of the neurotrophic factors acting in the central nervous system (CNS), prevents ordinary types of neuronal cell death induced by various stimulants. On the other hand, an accumulation of unfolded proteins in the endoplasmic reticulum (ER) leads to ER stress and then induces ER stress-mediated cell death. The ER stress-mediated cell death is distinctive because the caspase-12 activity plays a crucial role in the progression of cell death. We previously showed that nerve growth factor (NGF) attenuated ER stress-mediated cell death in non-neuronal PC12 cells. Here, we report that BDNF suppressed the ER stress-mediated cell death in tunicamycin (Tm)-treated cerebral cortical neurons. An analysis using a specific inhibitor of phosphatidylinositol 3-kinase (P13-K), LY294002, revealed that BDNF prevented this cell death via the P13-K signaling pathway. We found that the number of NeuN/TUNEL-double positive cells and the activity of caspase-3 suppressed by BDNF were increased by LY294002. We also discovered that LY294002 diminished the effect of BDNF on the activation of caspase-12, indicating that BDNF prevents ER stress-mediated cell death via a P13-K-dependent mechanism by suppressing the activation of caspase-12 in cultured CNS neurons. (C) 2004 Published by Elsevier B.V.

DOI： 10.1016/j.brainres.2004.09.005

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI IRELAND LTD  

Nicotine has been reported to have neuroprotective effects. The present study deals with the neuroprotective effect of nicotine on the tunicamycin-induced apoptosis of PC12h cells. Treatment of PC12h cells with tunicamycin causes endoplasmic reticulum stress leading to apoptosis. Nicotine dose-dependently prevented the tunicamycin-induced apoptosis. Hoechst 33258 staining demonstrated the protective effect of nicotine against tunicamycin-induced apoptosis. Treatment with nicotinic acetylcholine receptor (nAChR) and L-type voltage-sensitive calcium channel (L-VSCC) antagonists prevented the nicotine-induced protective effect. A phosphatidylinositol 3-kinase (PI3-K) inhibitor had no influence on the nicotine-induced neuroprotective effect. These results show that the neuroprotective effect of nicotine occurs through nAChRs including the alpha 7 subtype and L-VSCC in PC12h cells and not through the PI3-K/Akt pathway. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

DOI： 10.1016/j.neulet.2004.08.029

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

Following endoplasmic reticulum. (ER) stress, which occurs via inhibition of the glycosylation of newly synthesized proteins, caspase family proteins are activated to promote ER stress-mediated apoptosis. Here we report that nerve growth factor (NGF) suppressed the ER stress-mediated apoptosis in tunicamycin-treated PC12 cells through an extensive decrease of the caspase-3/-9/-12 activity. Detailed analysis of the mechanism underlying the NGF-mediated cell survival revealed that the activities of all seriate caspases were reduced through the phosphatidylinositol 3-kinase (PI3-K) signaling pathway induced by NGF. Moreover, we found that the activity of c-Jun N-terminal kinase (JNK) was not essential for the tunicamycin-induced apoptosis of PC12 cells. These results demonstrate that the inactivation of caspase-12 via the NGF-mediated PI3-K signaling pathway leads to inactivation of the caspase cascade including caspase-3 and -9.

DOI： 10.1093/jb/mvh053

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

On cell maturation following culture in medium containing 26 mM potassium (high K+; HK), a change to medium containing 5 mM potassium (low K+; LK) rapidly induces apoptosis in rat cerebellar granule neurons. Brain-derived neurotrophic factor (BDNF) and insulin-like growth factor-1 (IGF-1) have survival-promoting effects on the neurons via PI3-K. However, it remains unclear how they prevent the apoptosis in the pathway downstream of phosphatidylinositol-3 kinase (PI3-K). Recently, we have reported that PI3-K-ASK1 pathway is involved in signal-transduction to p38 MAPK (p38)-c-Jun pathway. Here we found that IGF-1 had a greater survival-promoting effect than BDNF, and activated PI3-K to a higher level and maintained the level for a longer time. BDNF and IGF-1 suppressed the activation of p38 and c-Jun, but not of c-Jun N-terminal kinase (JNK), caused by lowering the potassium concentration. The inhibitory effects of IGF-1 were much greater than those of BDNF. In addition, LY294002, a specific inhibitor of PI3-K, cancelled the inhibitory effects of BDNF and IGF-1. These results suggest that the greater inhibitory effects of IGF-1 than BDNF, on activation of p38 and c-Jun and apoptosis, are caused by the higher level of PI3-K activation during LK-induced apoptosis of cultured cerebellar granule neurons. (C) 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.molbrainres.2003.09.009

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPANESE BIOCHEMICAL SOC  

Previously, we reported that p38, which belongs to the mitogen-activated protein kinase (MAPK) superfamily, has an important role in the induction of apoptosis of cultured cerebellar granule neurons. However, the molecular mechanisms upstream of p38 activation remain unclear. Apoptosis signal-regulating kinase-1 (ASK1), a MAPK kinase kinase (MAPKKK) protein, is known to activate both c-Jun N-terminal kinase (JNK) and p38 via MAPK kinase (MKK) 4/7 and MKK3/6, respectively. Here, we examined whether ASK1 is involved in the activation of p38 in the low potassium (LK)-induced apoptosis of cerebellar granule neurons. We found that ASK1 was activated after a change to LK medium. In addition, the expression of ASK1-KM, a dominant-negative form of ASK1, using an adenovirus system was found to inhibit the activation of p38 and c-Jun and to prevent apoptosis. On the other hand, the expression of ASK1-DeltaN, a constitutively active form of ASK1, activated p38 and c-Jun, but not JNK, another possible downstream target of ASK1. Furthermore, we examined the relationship between phosphatidylinositol 3-kinase (PI3-K) and ASK1. The addition of LY294002, a specific inhibitor of PI3-K, enhanced the ASK1 activity. These results indicate that ASK1 works downstream of PI3-K to regulate the p38-c-Jun pathway and apoptosis in cultured cerebellar granule neurons.

DOI： 10.1093/jb/mvg092

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Kansai University Special Research Fund 200204-

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1-Methyl-4-phenyl-1,2,3,6-tetra-hydropyridine (MPTP) is a potent inducer of cell death, producing reactive oxygen species (ROS) and causing apoptosis in PC 12h cells at I mM [Shimoke et al., J. Neurosci. Res. 63 (2001) 402-409]. We showed here that MPTP also had a weak proliferative effect on PC12h at 500 muM when treated for 24 h. The proliferative effect was additive within 24 h cells when nerve growth factor (NGF) was present in the culture medium, but NGF promoted cell differentiation 2 or 3 days after. Use of PD98059, a specific inhibitor of MEK1 located upstream of extracellular signal-regulated kinases (ERKs), revealed that the NGF- and MPTP-induced proliferative effect depends on the MEK1 pathway because PD98059 diminished the proliferation completely, and interestingly, NGF and MPTP promoted sustained activation of ERKs. Moreover, we observed that MPTP increased the activity of p38 MAPK but not c-jun N-terminal kinase (JNK) in 30 min. We also observed that SB203580, a specific inhibitor of p38 MAPK, decreased cell viability. These results suggest that NGF and MPTP cooperate to promote acute cell proliferation via the sustained ERKs and the p38 MAPK pathway within 24 h in PC12h cells. (C) 2002 Elsevier Science B.V. All rights reserved.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BLACKWELL SCIENCE LTD  

Brain-derived neurotrophic factor (BDNF) and insulin-like growth factor-1 (IGF-1) act on various neurons of the CNS as neurotrophic factors promoting neuronal differentiation and survival. We examined the survival-promoting effects of BDNF and IGF-1 on serum deprivation-induced death in cultured cerebral cortical neurons, and compared the intracellular signaling pathways stimulated by BDNF and IGF-1 in the neurons. We found that the survival-promoting effect of BDNF was much weaker than that of IGF-1 in serum deprivation-induced death of cultured cortical neurons. We found no differences in the levels of phosphatidylinositol 3-kinase (Ptdlns3-K) activity or Akt (also called PKB) phosphorylation induced by BDNF and IGF-1 in the cultured cortical neurons, although many reports suggest that Ptdlns3-K and Akt are involved in survival promotion. In addition, phosphorylation signals of mitogen-activated protein kinase (MAPK) and cAMP responsive element-binding protein (CREB), which have also been reported to be involved in survival promotion, were stimulated by BDNF much more potently than by IGF-1. These results show that there may be, as yet unidentified, intracellular signaling pathways other than the Ptdlns3-K-Akt, MAPK and CREB signaling, to regulate survival promotion. These unidentified signaling pathways may be responsible for the distinct strengths of the survival-promoting effects of BDNF and IGF-1.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-LISS  

Nerve growth factor (NGF) mediates a variety of nerve cell actions through receptor tyrosine kinase TrkA. It has been revealed that the Akt pathway contributes to the prevention of apoptosis. It is thought that Parkinson's disease involves apoptosis, and NGF prevents apoptosis in an in vivo model system. However, there is no evidence that the Akt pathway helps to prevent parkinsonism. Here, we report that NGF prevents apoptosis induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in PC12 cells as an in vitro model system of parkinsonism and that this survival effect diminishes on addition of LY294002, a specific inhibitor of phosphatidylinositol 3-kinase. Immunocytochemical analysis revealed that 1 mM MPTP-treated cells or dominant negative Akt-expressing cells, to which were added NGF and MPTP, undergo apoptosis. Moreover, the caspase-3-like activity is increased by addition of MPTP or MPTP with NGF and LY294002. The importance of another signal pathway is shown by PD98059, a specific inhibitor of MAP kinase (MAPK) kinase, but PD98059 does not alter the survival effect in this model system. These results indicate that the Akt pathway helps to prevent parkinsonism by suppressing caspase-3-like activity, but the MAPK pathway is not involved in the NGF-dependent survival enhancing effect in this model system. (C) 2001 Wiley-Liss, Inc.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Cerebellar granule neurons maintained in medium containing 26 mM potassium or in medium (5 mM potassium) with 50 ng/ml brain-derived neurotrophic factor (BDNF) undergo an apoptotic cell death when exposed to 10 mu M LY294002, an inhibitor of phosphatidylinositol 3-kinase (PI3-K). To investigate the intracellular signaling mechanism of LY294002-induced apoptosis, the activities of Akt and c-Jun N-terminal kinase (JNK) were measured in cells in HK (26 mM potassium) medium or LK+ (5 mM potassium) medium containing BDNF, with or without 10 mu M LY294002. Akt activity decreased following the addition of 10 mu M LY294002. In addition, we found that LY294002 increased the JNK activity, which is known to mediate some types of cell death in cultured PNS neurons. We also observed elevated expression of c-Jun by LY294002 in HK+ or LK+ + BDNF. These findings demonstrated that apoptosis induced by inhibition of PI3-K activity involves suppression of the Akt activity and elevation of the JNK activity in cultured cerebellar granule neurons. Our results suggested that the PI3-K-Akt pathway suppresses the activation of JNK and c-Jun expression, and as a result prevents the neuronal cell death in cerebellar granule neurons. (C) 1999 Elsevier Science B.V. All rights reserved.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPRINGER-VERLAG TOKYO  

Cerebellar granule neurons obtained from 9-day-old rats die in an apoptotic manner when the neurons are cultured in serum-free medium containing a low concentration of potassium (5 mM). Brain-derived neurotrophic factor (BDNF) and a high concentration of potassium (26 mM) in the culture medium can effectively prevent this apoptosis. To examine which molecules are involved in the survival-promoting effect of BDNF on the apoptosis of cerebellar granule neurons, we used wortmannin, a specific inhibitor of phosphatidylinositol 3-kinase (PI3-K). Wortmannin inhibited the survival effect of BDNF and BDNF-induced increase of PI3-K activity in the cultured granule neurons. These results indicate that the preventive effect of BDNF on the apoptosis of cerebellar granule neurons is mediated by BDNF-stimulated activation of PI3-K.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

To examine which lipid product of phosphatidylinositol 3-kinase (PI3-K) is essential for the survival-promoting pathway in cultured cerebellar granule neurons, three synthetic derivatives of lipid products of PI3-K were added to culture medium containing a low concentration (5 mM) of potassium (LK+) which induces apoptotic cell death. We found that dipalmitoylphosphatidylinositol 3,4-bisphosphate and dipalmitoylphosphatidylinositol 3,4,5-trisphosphate, but not dipalmitoylphosphatidylinositol 3-monophosphate, effectively blocked the LK+-induced apoptosis. These two synthetic phospholipids increased Akt activity but not that of PI3-K. These findings demonstrated that specific lipid products of PI3-K which are added to culture medium activate Akt/PKB without modulating PI3-K itself, and as a result prevent neuronal cell death in cerebellar granule neurons. (C) 1998 Federation of European Biochemical Societies.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Cerebellar granule neurons obtained from 9-day-old rats die in an apoptotic manner when cultured in serum-free medium containing a low concentration of potassium (5 mM). A high concentration of potassium (26 mM) in the culture medium and BDNF can effectively prevent this apoptosis. The survival effects of high potassium and BDNF were additive, and the effect of high potassium was not blocked by addition of anti-BDNF antibody. These observations indicated that these survival effects were independent. To examine which molecules are involved in the survival pathway induced by BDNF or high K+, we used wortmannin, a specific inhibitor of PI-3 kinase. Wortmannin blocked the survival effects of both BDNF and high K+ on cerebellar granule neurons. Furthermore, in vitro PI-3 kinase assay showed that treatment with BDNF or high K+ induced PI-3 kinase activity, which was diminished by addition of wortmannin. These results indicate that different survival-promoting agents, BDNF and high K+, can prevent apoptosis in cerebellar granule neurons via a common enzyme, PI-3 kinase. (C) 1997 Elsevier Science B.V.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We investigated the signaling pathways exerted by brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) in relation to their survival-promoting effects on dissociated cultures of cerebellar granule cells prepared from postnatal 9-day-old rats. Granule neuron survival in culture was supported by BDNF, but not significantly by either nerve growth factor (NGF) or NT-3. BDNF and NT-3 resulted in not only the respective autophosphorylation of the Trk receptors, TrkB or TrkC, but also tyrosine phosphorylation of SHC, a protein involved in controlling p21(ras) activity, and phosphatidylinositol-3' (PI-3') kinase. NGF does not result in TrkA phosphorylation, In parallel, c-Sos was induced within 30 min, in response to BDNF and NT-3. NT-3 induced the phosphorylation of these proteins to a lesser extent than BDNF. BDNF also induced the tyrosine phosphorylation of phospholipase C gamma (PLC gamma), but the NT-3-induced one was not detected. We postulate that no survival promotion by NT-3 is due to lesser level of trkC expression and of the NT-3-induced signaling in the cultured cerebellar granule neurons. Wortmannin, a specific inhibitor of PI-3' inhibited the BDNF effect on neuronal survival. PI-3' kinase-dependent pathways might be involved in the promotion of cerebellar granule cell survival by BDNF.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Aromatic C-H bond activation of various methyl-substituted benzenes by the Pd(MeCO2)2-SBu2i system have been studied. In the case of p-xylene the new and unusual compound [(SBu2i)(2,5-Me2C6H3)Pd(mu-MeCO2)2Pd(mu-MeCO2)2Pd(2,5-Me2C6H3)(SBu2i)] (1) has been isolated. Complex 1 reacts with styrene and carbon monoxide to afford (E)-1-(2,5-dimethylphenyl)-2-phenylethene and 2,5-dimethylbenzene carboxylic acid, respectively. It has also been found that coupling products, biaryls, are formed in the reaction between Pd(MeCO2)2-SBu2i and methyl-substituted benzenes. The isolated aryl-palladium(II) complexes and the coupling products have been characterized and identified by means of H-1 NMR, GC-MS, and elemental analysis. On the basis of the isomer distribution of both isolated arylpalladium(II) complexes and the coupling products, the effect of the methyl groups on the benzene nucleus towards aromatic C-H bond activation is discussed.

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Language：Japanese   Publisher：関西大学先端科学技術推進機構  

CiNii Books

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：ELSEVIER IRELAND LTD  

DOI： 10.1016/j.neures.2010.07.2201

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Language：Japanese   Publisher：Kansai University  

CiNii Books

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Other Link： http://hdl.handle.net/10112/948

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J-GLOBAL

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Language：English  

CiNii Books

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Language：English   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Aromatic C-H bond activation of various methyl-substituted benzenes by the Pd(MeCO2)2-SBu2i system have been studied. In the case of p-xylene the new and unusual compound [(SBu2i)(2,5-Me2C6H3)Pd(mu-MeCO2)2Pd(mu-MeCO2)2Pd(2,5-Me2C6H3)(SBu2i)] (1) has been isolated. Complex 1 reacts with styrene and carbon monoxide to afford (E)-1-(2,5-dimethylphenyl)-2-phenylethene and 2,5-dimethylbenzene carboxylic acid, respectively. It has also been found that coupling products, biaryls, are formed in the reaction between Pd(MeCO2)2-SBu2i and methyl-substituted benzenes. The isolated aryl-palladium(II) complexes and the coupling products have been characterized and identified by means of H-1 NMR, GC-MS, and elemental analysis. On the basis of the isomer distribution of both isolated arylpalladium(II) complexes and the coupling products, the effect of the methyl groups on the benzene nucleus towards aromatic C-H bond activation is discussed.

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科研費基盤研究

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重点領域研究助成 200204-

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