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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It has recently been recognized that cellular stresses activate certain members of the mitogen-activated protein kinase (MAPK) superfamily. One role of these "stress-activated" MAPKs is to increase the transactivating activity of the transcription factors c-Jun, Elk1, and ATF2. These findings may be particularly relevant to hearts that have been exposed to pathological stresses. Using the isolated perfused rat heart, we show that global ischemia does not activate the 42- and 44-kD extracellular signal-regulated (protein) kinase (ERK) subfamily of MAPKs but rather stimulates a 38-kD activator of MAPK-activated protein kinase-2 (MAPKAPK2). This activation is maintained during reperfusion. The molecular characteristics of this protein kinase suggest that it is a member of the p38/reactivating kinase (RK) group of stress-activated MAPKs. In contrast, stress-activated MAPKs of the c-Jun N-terminal kinase (JNK/SAPKs) subfamily are not activated by ischemia alone but are activated by reperfusion following ischemia. Furthermore, transfection of ventricular myocytes with activated protein kinases (MEKK1 and SEK1) that may be involved in the upstream activation of JNK/ SAPKs induces increases in myocyte size and transcriptional changes typical of the hypertrophic response. We speculate that activation of multiple parallel MAPK pathways may be important in the responses of hearts to cellular stresses.
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PMID:Stimulation of the stress-activated mitogen-activated protein kinase subfamilies in perfused heart. p38/RK mitogen-activated protein kinases and c-Jun N-terminal kinases are activated by ischemia/reperfusion. 875 92

Stress-activated protein kinase (SAPK/JNK) has been implicated in the signaling pathway that leads to cell death. Carvedilol, a new vasodilating beta-adrenoceptor antagonist with potent antioxidant activity, has been shown to convey a high degree of cardioprotection in a variety of experimental models of myocardial ischemia as well as in patients with congestive heart failure. The present study was designed to explore whether the cardioprotective effects of carvedilol involve inhibition of SAPK activation. Ex vivo ischemia (30 min)-reperfusion (60-120 min) of the rabbit heart resulted in 67% reduction of pressure-rate product, 45% necrosis of left ventricular tissue and 62% loss of myocardial creatine kinase (P < 0.01 vs. basal). SAPK levels in the perfused hearts increased markedly following reperfusion (5.6-fold increase, P < 0.01 vs. basal). Carvedilol, at 10 microM, administered at time of reperfusion, enhanced recovery of pressure-rate product by 61%, reduced necrotic size by 65% and decreased myocardial creatine kinase loss by 62% (P < 0.01 vs. vehicle). Carvedilol also inhibited reperfusion-induced activation of SAPK by 61% (P<0.01 vs. vehicle). Carvedilol, at 1 microM, displayed a trend of cardioprotection and inhibition of SAPK activation. Our results suggest that SAPK may play a role in ischemia/reperfusion-induced cardiac injury and inhibition of SAPK activation by carvedilol may contribute to its cardioprotective effects.
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PMID:Carvedilol inhibits activation of stress-activated protein kinase and reduces reperfusion injury in perfused rabbit heart. 959 95

For many inherited and acquired hepatic diseases, liver transplantation is the only possible therapeutic strategy. Ischemia/reperfusion (I/R) damage to donor tissue is thought to be one component that may play a role in the decline of posttransplant tissue function and ultimately rejection. The transcription factors, AP-1 and nuclear factor kappaB (NF-kappaB), play important roles in the acute cellular responses to tissue damage, as well as the inflammatory phase following I/R. We have found that the DNA binding activity of AP-1 was dramatically increased following warm ischemia at 1 to 3 hours postreperfusion. Induced DNA binding activity was composed of predominately c-Jun and JunD hetero- and homodimers as determined by electrophoretic mobility supershift assays. This increase in AP-1 activity occurred in the absence of significant changes in the steady-state protein levels of c-Jun and JunB. Maximal activation of Jun amino-terminal kinase ( JNK) occurred within the 25 to 30 minutes postreperfusion, just before the peak in AP-1 DNA binding. These findings suggest that phosphorylation may play an important role in regulating AP-1 transcriptional complexes. Furthermore, JunD protein levels slightly increased at 3 hours postreperfusion, concordant with changes in AP-1 DNA binding activity. The activation of NF-kappaB at 1 hour postreperfusion was independent of proteolytic degradation of IkappaB- or IkappaB-beta. This activation of NF-kappaB DNA binding activity in the nucleus was preceded by an increase in tyrosine phosphorylation of IkappaB-. These studies suggest that JNK, IkappaB tyrosine kinase, and JunD are potential targets for therapeutic intervention during liver I/R injury.
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PMID:Ischemia/reperfusion injury in the liver of BALB/c mice activates AP-1 and nuclear factor kappaB independently of IkappaB degradation. 975 39

Transient global ischemia caused by 5 min of cardiac arrest induced delayed neuronal cell death (apoptosis) in the CA1 region of the rat hippocampus. To characterize the molecular mechanisms that regulate apoptosis in vivo, the contributions to cell death of mitogen-activated protein kinase family members were examined in the hippocampal region after brain ischemia-reperfusion. Ischemia-reperfusion led to a strong activation of the JNK/SAPK (c-Jun NH2-terminal protein kinase/stress activated protein kinase), ERK (extracellular signal-regulated kinase), and p38 enzymes. These results with other previous studies suggest that the activation of JNK/SAPK in accordance with p38 contributes to the induction of apoptosis in CA1 neurons.
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PMID:Delayed neuronal cell death in the rat hippocampus is mediated by the mitogen-activated protein kinase signal transduction pathway. 1007 72

Stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) is activated by a variety of cellular or environmental stresses. Proper regulation of the SAPK/JNK pathway may be critical for cell survival or death under various conditions. In this study, we report the molecular cloning of novel isoforms of JIP-1, which harbor a putative phosphotyrosine interaction domain and a helix-loop-helix domain, as well as an SH3 homologous region in the C terminus. Northern analysis indicates that transcription variant jip-1 is expressed in brain and kidney and transcription variants jip-2 and jip-3 are specifically expressed in brain. In situ hybridization data showed that the hybridized jip messages were heavily concentrated in adult brain, and were particularly enriched in the cerebral cortex and hippocampus, the brain regions vulnerable to pathological states such as hypoxia-ischemia, epilepsy, and Alzheimer's disease. All the deduced protein products of the jip transcription variants appear to have a similar property in that they inhibit the SAPK/JNK stimulation when overexpressed. Inhibition of SAPK activation by overexpression of the novel isoform JIP-2a resulted in suppression of etoposide-induced cell death in a neuroglioma cell line, N18TG. These findings suggest that JIP may play an important role in regulation of the SAPK pathway that is involved in stress-induced cellular responses.
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PMID:Molecular cloning of multiple splicing variants of JIP-1 preferentially expressed in brain. 1009 34

Both mitochondrial ATP-sensitive K+ (KATP) channels and the actin cytoskeleton have been proposed to be end-effectors in ischemic preconditioning (PC). For evaluation of the participation of these proposed end effectors, rabbits underwent 30 min of regional ischemia and 3 h of reperfusion. PC by 5-min ischemia + 10-min reperfusion reduced infarct size by 60%. Diazoxide, a mitochondrial KATP-channel opener, administered before ischemia was protective. Protection was lost when diazoxide was given after onset of ischemia. Anisomycin, a p38/JNK activator, reduced infarct size, but protection from both diazoxide and anisomycin was abolished by 5-hydroxydecanoate (5-HD), an inhibitor of mitochondrial KATP channels. Isolated adult rabbit cardiomyocytes were subjected to simulated ischemia by centrifuging the cells into an oxygen-free pellet for 3 h. PC was induced by prior pelleting for 10 min followed by resuspension for 15 min. Osmotic fragility was assessed by adding cells to hypotonic (85 mosmol) Trypan blue. PC delayed the progressive increase in fragility seen in non-PC cells. Incubation with diazoxide or pinacidil was as protective as PC. Anisomycin reduced osmotic fragility, and this was reversed by 5-HD. Interestingly, protection by PC, diazoxide, and pinacidil could be abolished by disruption of the cytoskeleton by cytochalasin D. These data support a role for both mitochondrial KATP channels and cytoskeletal actin in protection by PC.
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PMID:Ischemic preconditioning depends on interaction between mitochondrial KATP channels and actin cytoskeleton. 1019 63

Ischemic preconditioning is a phenomenon whereby exposure of the myocardium to a brief episode of ischemia and reperfusion markedly reduces tissue necrosis induced by a subsequent prolonged ischemia. Therefore, it is hoped that elucidation of the mechanism of preconditioning will yield therapeutic strategies capable of reducing myocardial infarction. In the rabbit, the brief period of preconditioning ischemia and reperfusion releases adenosine, bradykinin, opioids, and oxygen radicals that summate to induce the translocation and activation of protein kinase C (PKC). PKC appears to be the first element of a complex kinase cascade that is activated during the prolonged ischemia in preconditioned hearts. Current evidence indicates that PKC activates a tyrosine kinase that leads to the activation of p38 mitogen-activated protein (MAP) kinase or JNK, or possibly both. The stimulation of these stress-activated protein kinases ultimately induces the opening of mitochondrial K(ATP) channels that may be the final mediator of protection by ischemic preconditioning.
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PMID:Signal transduction in ischemic preconditioning: the role of kinases and mitochondrial K(ATP) channels. 1035 30

In this study, we investigate the in vivo activation of mitogen-activated protein kinases (MAPK) as important signal transduction cascades observed after myocardial ischemia/reperfusion. Myocardial continuous ischemia and ischemia/reperfusion was produced in Wistar rats. The activities of MAPKs in the ischemic and ischemia/reperfused regions were measured using an in-gel kinase assay, an in vitro kinase assay and Western blot analysis. Activator protein-1 (AP-1) DNA binding activity was determined using an electrophoretic mobility shift assay. DNA fragmentation was detected as DNA ladders by agarose gel electrophoresis. The p46JNK and p55JNK activities of continuous ischemia were significantly increased at 30 min (5.9 and 4.2 fold, respectively P<0.05). Coronary reperfusion increased both p42ERK and p44ERK activities at 30 min (3.0 and 2.3 fold P<0.01), and both p46JNK and p55JNK activities at 30 min (1.4 and 1.7 fold P<0.05). The AP-1 DNA binding activities of continuous ischemia were significantly increased at 1, 3 and 7 days (28, 21 and 17 fold, respectively P<0.01). Coronary reperfusion markedly decreased AP-1 DNA binding activities at 1 (41%P<0.01) and 3 days (48%P<0.05). Myocardial DNA fragmentation was considerably more enhanced by reperfusion than continuous ischemia. In conclusion, our present work provides the first in vivo evidence that ERK and JNK are activated by reperfusion from the activities of continuous ischemia. These signal transduction mechanisms may be partially responsible for the myocardial injury.
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PMID:Activation of mitogen-activated protein kinases in in vivo ischemia/reperfused myocardium in rats. 1037 1

The signal transduction pathways by which ischemia-reperfusion leads to apoptosis may involve the JNK pathway, ceramide generation, and inhibition of protective PKC pathways. The biochemical events associated with apoptosis include mitochondrial inactivation, cytochrome c dislocation, caspase activation, and cytoplasmic acidification. Through the concerted efforts of multiple classes of enzymes, apoptosis is accomplished, resulting in the death of a cell in which potentially transforming oncogenes have been degraded and inflammatory contents are contained within the plasma membrane until the fragments can be ingested by phagocytes. This non-inflammatory mode of cell death permits tissue remodeling with minimal scar formation, and so is preferable to necrotic cell death. The distinction between apoptosis and necrosis, which implies different mechanisms of cell death, is blurred in the case of a pathologic insult such as ischemia-reperfusion. It is suggested that it is more useful to view cell death in the context of whether or not it can be prevented.
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PMID:Apoptosis in myocardial ischemia-reperfusion. 1041 51

The purpose of this review is to discuss ATF3, a member of the ATF/CREB family of transcription factors, and its roles in stress responses. In the introduction, we briefly describe the ATF/CREB family, which contains more than 10 proteins with the basic region-leucine zipper (bZip) DNA binding domain. We summarize their DNA binding and heterodimer formation with other bZip proteins, and discuss the nomenclature of these proteins. Over the years, identical or homologous cDNA clones have been isolated by different laboratories and given different names. We group these proteins into subgroups according to their amino acid similarity; we also list the alternative names for each member, and clarify some potential confusion in the nomenclature of this family of proteins. We then focus on ATF3 and its potential roles in stress responses. We review the evidence that the mRNA level of ATF3 greatly increases when the cells are exposed to stress signals. In animal experiments, the signals include ischemia, ischemia coupled with reperfusion, wounding, axotomy, toxicity, and seizure; in cultured cells, the signals include serum factors, cytokines, genotoxic agents, cell death-inducing agents, and the adenoviral protein E1A. Despite the overwhelming evidence for its induction by stress signals, not much else is known about ATF3. Preliminary results suggest that the JNK/SAPK pathway is involved in the induction of ATF3 by stress signals; in addition, IL-6 and p53 have been demonstrated to be required for the induction of ATF3 under certain conditions. The consequences of inducing ATF3 during stress responses are not clear. Transient transfection and in vitro transcription assays indicate that ATF3 represses transcription as a homodimer; however, ATF3 can activate transcription when coexpressed with its heterodimeric partners or other proteins. Therefore, it is possible that, when induced during stress responses, ATF3 activates some target genes but represses others, depending on the promoter context and cellular context. Even less is understood about the physiological significance of inducing ATF3. We will discuss our preliminary results and some reports by other investigators in this regard.
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PMID:ATF3 and stress responses. 1044 Feb 33


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