Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanisms of ischemic cell damage are still not fully understood. It has been shown that alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionate (AMPA)/kainate receptor antagonists, such as 6-nitro-7- sulphamoyl-benzo-(f)-quinoxaline-2, 3-dione (NBQX), are neuroprotective in models of transient forebrain ischemia, even when applied during recovery, indicating that nonNMDA receptors may play a pivotal role in ischemic cell damage. In the present series of experiments, we studied whether transient cerebral ischemia causes changes in the extent of mRNA editing of AMPA/kainate receptor subunits, a reaction critical for the control of calcium flux through nonNMDA receptor ion channels. Transient cerebral ischemia was produced in rats using the four-vessel occlusion (4-VO) model. After 30 min of ischemia, brains were recirculated for 4, 8, or 24 h. Total RNA was extracted from the cortex, striatum, and hippocampus in order to analyze the extent of mRNA editing of the glutamate receptor subunits GluR2, GluR5, and GluR6. RNA was converted by reverse transcription into cDNA, which was used as a template for subunit-specific polymerase chain reaction (PCR) to amplify a product across the edited base A (A edited to I in the second transmembrane-spanning regions of GluR2, GluR5, and GluR6). PCR products were analyzed with the restriction enzyme Bbv 1, which recognizes the cDNA sequence GCAGC originating from unedited but not that originating from edited GluR2, GluR5, or GluR6 mRNA (GCGGC, the base I is read as G). Restriction digests were electrophoresed, and the bands visualized with ethidium bromide and then photographed. The extent of mRNA editing of the different subunits was quantified using image analysis and appropriate standards. In all control brains studied, GluR2 mRNA was completely edited and remained so after reversible cerebral ischemia. The extent of GluR5 mRNA editing was significantly upregulated in the striatum (from 39 +/- 6% in controls to 57 +/- 9 and 56 +/- 7 after 4 and 8 h of recovery, respectively, p < 0.05 versus control) but not in the cortex and hippocampus. The extent of GluR6 mRNA editing was significantly reduced after 24 h of recovery: in the cortex, from 92 +/- 1 to 78 +/- 6% (p < 0.01); in the striatum, from 91 +/- 2 to 79 +/- 1% (p < 0.001); and in the hippocampus, from 90 +/- 3 to 80 +/- 2% (p < 0.05). A significant reduction was already apparent in the striatum after 4 h of recovery (p < 0.05). Results indicate that mRNA editing is regulated differently in each of the glutamate receptor subunits GluR2, GluR5, and GluR6 after transient cerebral ischemia. The ischemia-induced upregulation of GluR5 mRNA editing observed in the striatum may be indicative of a higher sensitivity to transient ischemia of neurons that exhibit a large fraction of unedited GluR5 mRNA. This assumption is corroborated by the observation (Mackler and Eberwine, 1993) that GluR5 mRNA is completely unedited in neurons of the hippocampal CA1-subfield, a region most vulnerable to transient cerebral ischemia. Whether the decrease in GluR6 mRNA editing observed in all brain structures after ischemia results from a disturbance of the editing reaction or from glial proliferation will have to be established in further experiments. Studying ischemia-induced changes in mRNA editing of glutamate receptor subunits GluR5 and GluR6 may help to elucidate the molecular mechanisms of ischemic cell damage.
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PMID:RNA editing of glutamate receptor subunits GluR2, GluR5 and GluR6 in transient cerebral ischemia in the rat. 896 93

The postsynaptic density (PSD) is a cytoskeletal specialization involved in the anchoring of neurotransmitter receptors and in regulating the response of postsynaptic neurons to synaptic stimulation. The postsynaptic protein PSD-95 binds to NMDA receptor subunits NR2A and NR2B and to signaling molecules such as neuronal nitric oxide synthase and p135synGAP. We investigated the effects of transient cerebral ischemia on protein interactions involving PSD-95 and the NMDA receptor in the rat hippocampus. Ischemia followed by reperfusion resulted in a decrease in the solubility of the NMDA receptor and PSD-95 in 1% sodium deoxycholate, the decrease being greater in the vulnerable CA1 hippocampal subfield than in the less sensitive CA3/dentate gyrus regions. Solubilization of the kainic acid receptor GluR6/7 and the PSD-95 binding proteins, neuronal nitric oxide synthase and p135synGAP, also decreased following ischemia. The association between PSD-95 and NR2A and NR2B, as indicated by coimmunoprecipitation, was less in postischemic samples than in sham-operated controls. Ischemia also resulted in a decrease in the size of protein complexes containing PSD-95, but had only a small effect on the size distribution of complexes containing the NMDA receptor. The results indicate that molecular interactions involving PSD-95 and the NMDA receptor are modified by an ischemic challenge.
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PMID:Altered interaction between PSD-95 and the NMDA receptor following transient global ischemia. 1061 18

In this study, we investigated the effect of PSD-95 antisense oligodeoxynucleotides on the phosphorylation of MLK3, JNK3 and interactions of MLK3 and PSD-95 with kainate receptor (GluR6) by immunoprecipitation and immunoblotting. Transient (15 min) brain ischemia was induced by the four-vessel occlusion in Sprague-Dawley rats. The antisense oligodeoxynucleotides of PSD-95 were administrated to the SD rats once per day for 3 days before ischemia. Our data show that the antisense oligodeoxynucleotides could inhibit phosphorylation of MLK3 and JNK3 and decrease the interactions of MLK3 and PSD-95 with GluR6. These results indicate that PSD-95 plays an important role in the formation of the GluR6.PSD-95.MLK3 signaling module and MLK3 and JNK3 activation in postischemic rat hippocampus.
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PMID:Postsynaptic density protein 95 antisense oligodeoxynucleotides inhibits the activation of MLK3 and JNK3 via the GluR6.PSD-95.MLK3 signaling module after transient cerebral ischemia in rat hippocampus. 1530

Recent studies have shown that GluR6 is involved in the modulation of neuronal cell death. It has been shown that PKA can phosphorylate recombinant GluR6 homomeric receptors and that this phosphorylation of GluR6 was suggested to underlie an enhancement of whole-cell current responses. Here, we try to find out whether brain ischemia and reperfusion could induce any change in the serine phosphorylation of GluR6. Our results showed that the serine phosphorylation of GluR6 increased in hippocampus during brain ischemia and early reperfusion period. Then, we used several drugs to investigate the mechanism of modulating the serine phosphorylation of GluR6. KT5720, a specific cell-permeable inhibitor of protein kinase A (PKA), had no effect on the increase in serine phosphorylation of GluR6 induced by brain ischemia or reperfusion. On the other hand, KN-62, a selective inhibitor of rat brain Ca(2+)/calmodulin-dependent protein kinase II (CaMKII), diminished the increase in serine phosphorylation of GluR6. Moreover, our results showed that either MK801 (a NMDA receptor antagonist) or Nifedipine (a L-type Ca2+ channel (L-VGCC) blocker) decreased the increase in serine phosphorylation. In conclusion, our results suggest that CaMKII, activated through NMDA receptors and L-VGCCs, mediated the serine phosphorylation of GluR6 during brain ischemia and early reperfusion period.
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PMID:Calcium/calmodulin-dependent protein kinase II (CaMKII), through NMDA receptors and L-Voltage-gated channels, modulates the serine phosphorylation of GluR6 during cerebral ischemia and early reperfusion period in rat hippocampus. 1612 2

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

To investigate whether the kainate (KA) receptors subunit GluR6 is involved in the neuronal cell death induced by cerebral ischemia followed by reperfusion, the antisense oligodeoxynucleotides (ODNs) of GluR6 were used to suppress the expression of GluR6 by intracerebroventricular infusion once per day for 3 days before ischemia. Transient brain ischemia was induced by four-vessel occlusion in Sprague-Dawley rats. The effects of GluR6 antisense ODNs on the phosphorylation of MLK3 and JNK and the interactions of MLK3 and PSD-95 with GluR6 were examined by immunoprecipitation and immunoblotting. Our results show that GluR6 antisense ODNs can knock down the expression of GluR6 and suppress the assembly of the GluR6.PSD-95.MLK3 signaling module and, therefore, inhibit JNK activation and phosphoralation of c-jun. On the other hand, the GluR6 antisense ODNs also show a protective role against neuronal cell death induced by cerebral ischemia/reperfusion. Administration of GluR6 antisense ODNs once per day for 3 days before cerebral ischemia significantly decreased neuronal degeneration. In conclusion, our results demonstrate that kainate receptor subunit GluR6 plays an important role in neuronal death induced by cerebral ischemia followed by reperfusion.
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PMID:Neuroprotective effects of GluR6 antisense oligodeoxynucleotides on transient brain ischemia/reperfusion-induced neuronal death in rat hippocampal CA1 region. 1626 25

The serum- and glucocorticoid-inducible kinase-1 (SGK1) is ubiquitously expressed and under genomic control by cell stress (including cell shrinkage) and hormones (including gluco- and mineralocorticoids). Similar to its isoforms SGK2 and SGK3, SGK1 is activated by insulin and growth factors via phosphatidylinositol 3-kinase and the 3-phosphoinositide-dependent kinase PDK1. SGKs activate ion channels (e.g., ENaC, TRPV5, ROMK, Kv1.3, KCNE1/KCNQ1, GluR1, GluR6), carriers (e.g., NHE3, GLUT1, SGLT1, EAAT1-5), and the Na+-K+-ATPase. They regulate the activity of enzymes (e.g., glycogen synthase kinase-3, ubiquitin ligase Nedd4-2, phosphomannose mutase-2) and transcription factors (e.g., forkhead transcription factor FKHRL1, beta-catenin, nuclear factor kappaB). SGKs participate in the regulation of transport, hormone release, neuroexcitability, cell proliferation, and apoptosis. SGK1 contributes to Na+ retention and K+ elimination of the kidney, mineralocorticoid stimulation of salt appetite, glucocorticoid stimulation of intestinal Na+/H+ exchanger and nutrient transport, insulin-dependent salt sensitivity of blood pressure and salt sensitivity of peripheral glucose uptake, memory consolidation, and cardiac repolarization. A common ( approximately 5% prevalence) SGK1 gene variant is associated with increased blood pressure and body weight. SGK1 may thus contribute to metabolic syndrome. SGK1 may further participate in tumor growth, neurodegeneration, fibrosing disease, and the sequelae of ischemia. SGK3 is required for adequate hair growth and maintenance of intestinal nutrient transport and influences locomotive behavior. In conclusion, the SGKs cover a wide variety of physiological functions and may play an active role in a multitude of pathophysiological conditions. There is little doubt that further targets will be identified that are modulated by the SGK isoforms and that further SGK-dependent in vivo physiological functions and pathophysiological conditions will be defined.
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PMID:(Patho)physiological significance of the serum- and glucocorticoid-inducible kinase isoforms. 1701 87

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

Our previous study indicates that global ischemia facilitates the assembly of the GluR6.PSD-95.MLK3 signaling module, which in turn activated MLK3, leading to exacerbated ischemic neuron death. In addition, JIP1, functioning as a scaffold protein, could couple MLK3-MKK7-JNK to form a specific signaling module and facilitate the activation of the JNK signal pathway. However, the organization, regulation, and function between the two signaling modules and the effects they have on MLK3 activation remain incompletely understood. Here, we show that JIP1 maintains MLK3 in an inactive and monomeric state; once activated, MLK3 binds to PSD-95 and then dimerizes and autophosphorylates. In addition, a GluR6 C-terminus-containing peptide (Tat-GluR6-9c) and antisense oligonucleotides (AS-ODNs) against PSD-95 inhibit the integration of PSD-95 and MLK3 and the dimerization of MLK3, facilitate the interaction of JIP1 and MLK3, and, consequently, perform neuroprotection on neuron death. However, AS-ODNs against JIP1 play a negative role compared to that mentioned above. The findings show that the crosstalk occurs between PSD-95 and the JIP1-mediated signaling module, which may be involved in brain ischemic injury and contribute to the regulation of MLK3 activation. Thus, specific blockade of PSD-95-MLK3 coupling may reduce the extent of ischemia-reperfusion-induced neuronal cell death.
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PMID:Crosstalk between PSD-95 and JIP1-mediated signaling modules: the mechanism of MLK3 activation in cerebral ischemia. 1734 86

Kainate receptor containing GluR6 subunit (KAR) is involved in the neuronal cell death induced by cerebral ischemia/reperfusion (I/R). Hypothermia is an effective neuroprotectant in brain ischemia, whereas the neuroprotective mechanisms have not been clearly established. The present study was set out to examine whether hypothermia would cause the alternation of the assembly of the GluR6-PSD95-MLK3 signaling module and the activation of c-Jun N-terminal kinase (JNK) pathway through KAR. Hypothermia (32 degrees C) was induced 10 min before ischemia and was maintained for 3 h after ischemia. Our results indicated that hypothermia could inhibit the assembly of GluR6-PSD95-MLK3 signaling module and suppressed the activation of MLK3, MKK4/7, and JNK3. The inhibition of JNK3 activation by hypothermia diminished the phosphorylation of the transcription factor c-Jun and downregulated FasL expression in hippocampal CA1. Meanwhile, the inhibition of JNK3 activation by hypothermia attenuated bax translocation, the release of cytochrome c, and the activation of caspase-3 in CA1 subfields. Both GluR6 antagonist NS102 and GluR6 antisense oligodeoxynucleotides partly blocked the aforementioned effects of hypothermia, which was further confirmed by histology. Taken together, our results strongly suggest that hypothermia decreased the increased assembly of the GluR6-PSD95-MLK3 signaling module and the activation of JNK pathway induced by I/R through KAR, which gave a new insight into the ischemic therapy.
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PMID:Neuroprotection of hypothermia against neuronal death in rat hippocampus through inhibiting the increased assembly of GluR6-PSD95-MLK3 signaling module induced by cerebral ischemia/reperfusion. 1817 94


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