Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0917798 (cerebral ischemia)
 17,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Kainate receptor glutamate receptor 6 (GluR6) binds to the postsynaptic density protein 95 (PSD-95), which in turn anchors mixed lineage kinase 3 (MLK3) via SH3 domain in rat brain tissue. MLK3 subsequently activates c-Jun NH(2)-terminal kinase (JNK) via MAP kinase kinases (MKKs). We investigated the association of PSD-95 with GluR6 and MLK3, MLK3 autophosphorylation, the interaction of MLK3 with JNK3, and JNK3 phosphorylation following cerebral ischemia in rat hippocampus. Our results indicate that the GluR6.PSD-95.MLK3 complex peaked at 6 h of reperfusion. Furthermore, MLK3 autophosphorylation and the interaction of MLK3 with JNK3 occurred with the alteration of GluR6.PSD-95.MLK3 signaling module. To further prove whether JNK3 activation in ischemic hippocampus is mediated by GluR6.PSD-95.MLK3 signaling pathway, the AMPA/KA receptor antagonist 6,7-dinitroquinoxaline-2, (1H, 4H)-dione (DNQX), the GluR6 antagonist 6,7,8,9-Tetrahydro-5-nitro-1H-benz[g]indole-2,3-dione-3-oxime (NS102), the AMPA receptor antagonist 1-(4-aminophenyl)-4-methyl-7,8-methylenedioxy-5H-2,3-benzo diazepine (GYKI52466), and the NMDA receptor antagonist ketamine were given to the rats 20 min prior to ischemia. Our findings indicate that both DNQX and NS102 significantly attenuated the association of PSD-95 with GluR6 and MLK3, MLK3 autophosphorylation, interaction of MLK3 with JNK3, and JNK3 phosphorylation, while GYKI52466 and ketamine had no effect. Moreover, administration of NS102 before cerebral ischemia significantly increased the number of the surviving hippocampal CA1 pyramidal cells at 5 days of reperfusion. Consequently, GluR6, one subunit of kainate receptor, plays a critical role in inducing JNK3 activation after ischemic injury.
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PMID:Activation of c-Jun NH2-terminal kinase 3 is mediated by the GluR6.PSD-95.MLK3 signaling module following cerebral ischemia in rat hippocampus. 1625 62

Cerebral ischemia induces kainate receptor glutamate receptor 6 (GluR6) binding to the postsynaptic density protein 95 (PSD95), which in turn anchors mixed lineage kinase 3 (MLK3) via SH3 domain in rat brain. MLK3 subsequently activates c-Jun NH(2)-terminal kinase (JNK) via MAP kinase kinases (MKKs). In this study, we investigated the association of PSD95 with GluR6 and MLK3, the autophosphorylation of MLK3, the combination of MLK3 with JNK3, and the phosphorylation of JNK3 during cerebral ischemia in rat hippocampus CA1. Our results indicate that the GluR6-PSD95-MLK3 complex quickly enhanced at 5 min of ischemia and peaked at 10 min of ischemia, and then gradually reduced with the prolonged time of ischemia. Interestingly, the combination of MLK3 and JNK3 gradually increased from 5 min to 30 min of ischemia. JNK3 phosphorylation first increased and then attenuated in cytosol, suggesting the translocation of activated JNK3 to nucleus during ischemia. To further investigate the possible mechanism of JNK3 activation, antioxidant N-acetylcysteine (NAC) was given to the rats 20 min prior to ischemia. Results indicate that NAC distinctly inhibited the association of PSD95 with GluR6 and MLK3, the autophosphorylation of MLK3, the combination of MLK3 with JNK3 and JNK3 activation. Taken together, these finding indicate that ischemic stimulation results in JNK3 activation through the GluR6-PSD95-MLK3 signaling module, and that the activation of JNK3 is closely related to oxidative stress.
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PMID:Antioxidant N-acetylcysteine inhibits the activation of JNK3 mediated by the GluR6-PSD95-MLK3 signaling module during cerebral ischemia in rat hippocampus. 1703 Apr 33

S-nitrosylation, as a post-translational protein modification, recently has been paid more and more attention in stroke research. S-nitrosylation regulates protein function by the mechanisms of covalent attachment that control the addition or the removal of nitric oxide (NO) from a cysteine thiol. The derivation of NO is established by the demonstration that, in cerebral neurons, NO mainly generates from neuronal nitric oxide synthase (nNOS) during the early stages of reperfusion. In the past researches, we demonstrate that global ischemia-reperfusion facilitates the activation of glutamate receptor 6 (GluR6) -mediated c-Jun N-terminal kinase (JNK) signaling pathway. The objective of this study is primarily to determine, during the early stages of reperfusion in rat four-vessel occlusion (4-VO) ischemic model, whether nNOS-derived NO affects the GluR6-mediated JNK signaling route via S-nitrosylation which is performed mainly by the biotin switch assay. Here, we show that administration of 7-nitroindazole, an inhibitor of nNOS, or ketamine, an antagonist of N-methyl-d-aspartate receptor (NMDAR), diminishes the increased S-nitrosylation of GluR6 induced by cerebral ischemia-reperfusion. In contrast, 2-amion-5,6-dihydro-6-methyl-4H-1,3-thiazine, an inhibitor of inducible NO synthase does not affect S-nitrosylation of GluR6. Moreover, treatment with sodium nitroprusside (SNP), an exogenous NO donor, increases the S-nitrosylation and phosphorylation of nNOS, leading to the attenuation of the increased S-nitrosylation of GluR6 and the assembling of GluR6* postsynaptic density protein 95 (PSD95)* mixed lineage kinase 3 (MLK3) signaling module induced by cerebral ischemia-reperfusion. The results also show that GluR6 downstream MLK3* mitogen activated protein kinase kinase 4/7* JNK signaling module and nuclear or non-nuclear apoptosis pathways are involved in the above signaling route. However, dithiothreitol (DTT) antagonizes the neuroprotection of SNP. Treatment with DTT alone, as a negative control, prevents S-nitrosylation of proteins, which indicates the existence of endogenously produced S-nitrosylation. These data suggest that GluR6 is S-nitrosylated by endogenous NO in cerebral ischemia-reperfusion, which is possibly correlated with NMDAR* PSD95* nNOS signaling module, and further activates GluR6* PSD95* MLK3 signaling module and JNK signaling pathway. In contrast, exogenous NO donor antagonizes the above action of endogenous NO generated from nNOS. Thus, our results provide the coupling of nNOS with GluR6 by S-nitrosylation during the early stages of ischemia-reperfusion, which can be a new approach for stroke therapy.
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PMID:Coupling between neuronal nitric oxide synthase and glutamate receptor 6-mediated c-Jun N-terminal kinase signaling pathway via S-nitrosylation contributes to ischemia neuronal death. 1867 85

In our previous studies, Tat-GluR6-9c (a glutamate receptor 6 C-terminus peptide fused the TAT protein transduction sequence) not only inhibited the activation of MLK3 (mixed lineage kinase 3) and JNK (c-Jun N-terminal kinase) via the GluR6.PSD-95 (postsynaptic density protein 95).MLK3 signaling module but also diminished neuronal death induced by kainic acid or transient cerebral ischemia in rat hippocampus. Here, we investigate whether overexpression of the PDZ1 domain of PSD-95 protein could suppress the binding of GluR6 with PSD-95 and the activation of MLK3, MKK7 (mitogen-activated kinase kinase 7) and JNK1/2, and rescused neuronal cell death induced by kainic acid. Our results showed that overexpression of the PDZ1 domain of PSD-95 protein could prevent nuclear accumulation and abrogate neuronal cell death in SD (Sprague-Dawley) rat hippocampal neuronal cells. Further studies indicated that overexpression of PDZ1 could inhibit the enhancement of binding of GluR6 to PSD-95 and prevent the activation of MLK3, MKK7 and JNK1/2 induced by kainic acid. Taken together, the essential role of the PDZ1 domain of PSD-95 in apoptotic cell death in neurons provides an experimental foundation for gene therapy of neurodegenerative diseases with overexpression of the PDZ1 domain.
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PMID:Overexpression of PDZ1 domain prevents apoptosis of rat hippocampal neurons induced by kainic acid. 1947 22

GluR6 kainate receptor subunit is largely expressed in hippocampus of brain regions and plays an important role in brain ischemia/reperfusion-mediated neuronal cell death. Our previous researches have shown that cerebral ischemia/reperfusion could facilitate the assembly of GluR6 and postsynaptic density protein 95(PSD95) as well as mixed lineage kinase 3(MLK3) and further induce the activation of c-Jun NH2-terminal kinase 3(JNK3), leading to neuronal death of hippocampal CA1. Here, we show that over-expression of C-terminal amino acids of GluR6 can interrupt the combination of GluR6 with PSD95, inhibit the assembly of GluR6.PSD-95.MLK3 signaling module, suppress the activation of JNK3 and the downstream signaling pathway. Thus, our results imply that over-expression of C-terminal amino acids of GluR6 induce neuroprotection against ischaemic brain injury in rat hippocampal CA1 region via suppressing proapoptosis signaling pathways, which can be an experimental foundation for gene therapy of stroke.
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PMID:Inhibition of cerebral ischemia/reperfusion-induced injury by adenovirus expressed C-terminal amino acids of GluR6. 1974 68

Previous studies in our laboratory have shown that mixed lineage kinase 3 (MLK3) can be activated following global ischemia. In addition, other laboratories have reported that the activation of MLK3 may be linked to the accumulation of free radicals. However, the mechanism of MLK3 activation remains incompletely understood. We report here that MLK3, overexpressed in HEK293 cells, is S-nitrosylated (forming SNO-MLK3) via a reaction with S-nitrosoglutathione, an exogenous nitric oxide (NO) donor, at one critical cysteine residue (Cys-688). We further show that the S-nitrosylation of MLK3 contributes to its dimerization and activation. We also investigated whether the activation of MLK3 is associated with S-nitrosylation following rat brain ischemia/reperfusion. Our results show that the administration of 7-nitroindazole, an inhibitor of neuronal NO synthase (nNOS), or nNOS antisense oligodeoxynucleotides diminished the S-nitrosylation of MLK3 and inhibited its activation induced by cerebral ischemia/reperfusion. In contrast, 2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine (an inhibitor of inducible NO synthase) or nNOS missense oligodeoxynucleotides did not affect the S-nitrosylation of MLK3. In addition, treatment with sodium nitroprusside (an exogenous NO donor) and S-nitrosoglutathione or MK801, an antagonist of the N-methyl-D-aspartate receptor, also diminished the S-nitrosylation and activation of MLK3 induced by cerebral ischemia/reperfusion. The activation of MLK3 facilitated its downstream protein kinase kinase 4/7 (MKK4/7)-JNK signaling module and both nuclear and non-nuclear apoptosis pathways. These data suggest that the activation of MLK3 during the early stages of ischemia/reperfusion is modulated by S-nitrosylation and provides a potential new approach for stroke therapy whereby the post-translational modification machinery is targeted.
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PMID:S-nitrosylation of mixed lineage kinase 3 contributes to its activation after cerebral ischemia. 2212 24

Fasudil hydrochloride (FH), a Rho kinase (ROCK) inhibitor, has been reported to prevent cerebral ischemia in vivo from increasing cerebral blood flow and inhibiting inflammatory responses. However, it is uncertain by what mechanism a ROCK inhibitor can directly protect neurons against ischemic damage. The present study was designed to evaluate whether FH decreased the increased phosphorylation of glutamate receptor 6 (GluR6) and its downstream in GluR6-MLK3-JNKs signal transduction pathway following global transient cerebral ischemia, as a result of protecting against neuronal apoptosis and death. Transient cerebral ischemia was induced by the Pulsinelli-Brierley four-vessel occlusion method. FH (15 mg/kg) was administered to rats by intraperitoneal injection 30 min before ischemia. The phosphorylation and protein expression of GluR6 at 6 h during reperfusion were detected using immunoprecipitation and immunoblotting analysis. The phosphorylation and protein expression of Mixed lineage kinase 3 (MLK3) at ischemia/reperfusion (I/R) 6 h and c-Jun N-terminal kinase (JNK) at I/R 3 d were detected using immunoblotting analysis, respectively. The same method was used to detect the expression of caspase-3 at I/R 6 h. Furthermore, we also use TUNEL staining and Cresyl violet staining to examine the survival neurons in rat hippocampal CA1 regions after 3 and 5 d reperfusion, respectively. Our study indicated that FH could inhibit the increased phosphorylation of GluR6 and MLK3 and the expression of caspase-3 at peaked 6 h of reperfusion and the phosphorylation of JNK (3 d) (p < 0.5). The results of TUNEL staining and Cresyl violet showed that the number of surviving pyramidal neurons in rats hippocampal CA1 subfield increased markedly in FH-treated rats compared with ischemic groups after 3 or 5 d of reperfusion following ischemia (p < 0.5). These results suggested that FH, as a ROCK inhibitor, may be partly responsible for its protective effects against such damage by taking part in GluR6-MLK3-JNKs signaling pathway which modulates ischemic damage. Taken together, this is the first study investigating Rho and ROCK as the upstream of GluR6 taking part in GluR6-MLK3-JNKs signal transduction pathway following cerebral ischemia.
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PMID:Fasudil hydrochloride protects neurons in rat hippocampal CA1 region through inhibiting GluR6-MLK3-JNKs signal pathway. 2479 42