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)

Previous studies utilizing crude brain homogenates have shown that forebrain ischemia results in inhibition of calcium/calmodulin-dependent protein kinase II (CaM kinase II) activity without large-scale proteolysis of the enzyme. In this report, a monoclonal antibody (1C3-3D6) directed against the beta- (60-kDa) subunit of CaM kinase II that does not recognize ischemically altered enzyme was utilized to further investigate the ischemia-induced inhibition of CaM kinase II. Immunohistochemical investigations showed that the ischemia-induced decreased immunoreactivity of CaM kinase II occurred immediately following ischemic insult in ischemia-sensitive cells such as pyramidal cells of the hippocampus. No decrease in CaM kinase II immunoreactivity was observed in ischemia-resistant cells such as granule cells of the dentate gyrus. The decreased immunoreactivity was observed for CaM kinase II balanced for protein staining and calmodulin binding in vitro. In addition, autophosphorylation of CaM kinase II in the presence of low (7 microM) or high (500 microM) ATP did not alter immunoreactivity of the enzyme with 1C3-3D6. The data demonstrate the production of a monoclonal antibody that recognizes the beta-subunit of CaM kinase II in a highly specific manner, but does not recognize ischemic enzyme. Together with previous studies, the data support the hypothesis that rapid, ischemia-induced inhibition of CaM kinase II activity may be involved in the cascade of events that lead to selective neuronal cell loss in stroke.
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PMID:Global forebrain ischemia results in decreased immunoreactivity of calcium/calmodulin-dependent protein kinase II. 132 53

The activity of multifunctional calcium/calmodulin-dependent protein kinase II (CaM kinase II) has recently been shown to be inhibited by transient global ischemia. To investigate the nature of ischemia-induced inhibition of the enzyme, CaM kinase II was purified to greater than 1,000-fold from brains of control and ischemic gerbils. The characteristics of CaM kinase II from control and ischemic preparations were compared by numerous parameters. Kinetic analysis of purified control and ischemic CaM kinase II was performed for autophosphorylation properties, ATP, magnesium, calcium, and calmodulin affinity, immunoreactivity, and substrate recognition. Ischemia induced a reproducible inhibition of CaM kinase II activity, which could not be overcome by increasing the concentration of any of the reaction parameters. Ischemic CaM kinase II was not different from control enzyme in affinity for calmodulin, Ca2+, Mg2+, or exogenously added substrate or rate of autophosphorylation. CaM kinase II isolated from ischemic gerbils displayed decreased immunoreactivity with a monoclonal antibody (immunoglobulin G3) directed toward the beta subunit of the enzyme. In addition, ischemia caused a significant decrease in affinity of CaM kinase II for ATP when measured by extent of autophosphorylation. To characterize further the decrease in ATP affinity of CaM kinase II, the covalent-binding ATP analog 8-azido-adenosine-5'-[alpha-32P]triphosphate was used. Covalent binding of 25 microM azido-ATP was decreased 40.4 +/-12.3% in ischemic CaM kinase II when compared with control enzyme (n = 5; p less than 0.01 by paired Student's t test). Thus, CaM kinase II levels for ischemia and control fractions were equivalent by protein staining, percent recovery, and calmodulin binding but were significantly different by immunoreactivity and ATP binding. The data are consistent with the hypothesis that ischemia induces a posttranslational modification that alters ATP binding in CaM kinase II and that results in an apparent decrease in enzymatic activity.
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PMID:Global forebrain ischemia induces a posttranslational modification of multifunctional calcium- and calmodulin-dependent kinase II. 132 15

Cerebral ischemia produces a disruption of calcium homeostasis in neurons. This may explain the extreme sensitivity of these cells to ischemic insult. Prolonged increases in calcium levels may produce irreversible damage to the cell by altering important calcium-dependent enzyme systems such as calcium/calmodulin-dependent protein kinase II. Five minutes of acute forebrain ischemia in the gerbil produced a significant decrease in calcium/calmodulin-dependent protein kinase II activity as early as 10 seconds postischemia and persisting up to 7 days after insult. Because hypothermia protects against ischemia-induced cell death in the gerbil, we examined the effect of ischemia on cell death and calcium/calmodulin-dependent protein kinase II at different intracerebral temperatures: hyperthermia (39 degrees C), normothermia (36 degrees C), and hypothermia (32 degrees C). In ischemic animals, hyperthermia produced severe loss of neurons in CA1 and moderate loss in CA3-CA4 subregions. Normothermia in ischemic animals produced severe loss of neurons in the CA1 subregion. Hypothermic ischemic animals showed no significant loss of neurons in any hippocampal region. Ischemia produced a severe decrease (17 +/- 6% of control) in calcium/calmodulin-dependent kinase II activity in hyperthermic animals, a moderate decrease (55 +/- 15% of control) in normothermic animals, and no decrease of enzyme activity in hypothermic animals. Thus, lowering and raising intracerebral temperature decreased and increased, respectively, the extent of ischemia-induced damage in the gerbil. Because ischemia-induced effects on calcium/calmodulin-dependent protein kinase II activity are rapid and long-lasting, hypothermia may protect through preservation of calcium/calmodulin-dependent protein kinase II activity.
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PMID:Effects of ischemia on multifunctional calcium/calmodulin-dependent protein kinase type II in the gerbil. 217 73

We used brief bilateral carotid artery occlusion in gerbils to examine the effects of temperature on ischemia-induced inhibition of calcium/calmodulin-dependent protein kinase II activity and neuronal death. In normothermic (36 degrees C) gerbils, ischemia induced a severe loss of hippocampal CA1 pyramidal neurons measured 7 days after ischemia (28.4 neurons/mm, n = 10; control density in 10 naive gerbils 262.1 neurons/mm) and a significant decrease in forebrain calcium/calmodulin-dependent protein kinase II autophosphorylation measured 2 hours after ischemia (12.9 fmol/min, n = 6; control phosphorylation in six naive gerbils 23.5 fmol/min). The effect of temperature on these indicators of ischemic damage was examined by adjusting intracerebral temperature before and during the ischemic insult. Hyperthermic (39 degrees C) gerbils showed almost complete loss of neurons in the CA1 region (3.0 neurons/mm, n = 11) and extension of neuronal death into the CA2, CA3, and CA4 regions. In addition, hyperthermia exacerbated ischemia-induced inhibition of calcium/calmodulin-dependent protein kinase II activity (4.2 fmol/min, n = 6). Hypothermia (32 degrees C) protected against ischemia-induced CA1 pyramidal cell damage (257.0 neurons/mm, n = 20) and inhibition of calcium/calmodulin-dependent protein kinase II activity (26.0 fmol/min, n = 6). Our results are consistent with the hypothesis that loss of calcium/calmodulin-dependent protein kinase II activity may be a critical event in the development of ischemia-induced cell death.
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PMID:Temperature modulation of ischemic neuronal death and inhibition of calcium/calmodulin-dependent protein kinase II in gerbils. 226 78

This study analyzed the ability of the N-methyl-D-aspartate receptor antagonist dextrorphan (DX) to prevent neuronal degeneration (analyzed by light microscopy), calmodulin (CaM) redistribution (analyzed by immunocytochemistry) and changes in activity of two major Ca(2+)-dependent protein kinases--calcium/calmodulin-dependent protein kinase II (CaM-KII) and protein kinase C (PKC) (analyzed by specific substrate phosphorylation) after 20 min of global ischemia (four-vessel occlusion model) in rats. DX treatment before and after ischemia significantly protected hippocampal and cortical neurons from neurodegeneration whereas DX posttreatment alone did not have any effect on preservation of neuronal morphology as compared with placebo treatment analyzed 72 h after 20 min of ischemia. Similarly to histological changes, DX exhibited protection against redistribution of CaM observed after ischemia. These changes were detected both in hippocampus as well as in cerebral cortex. Finally, DX administered before ligation of the carotid arteries reduced loss in both CaM-KII and PKC activity evoked by ischemia.
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PMID:Neuronal protection and preservation of calcium/calmodulin-dependent protein kinase II and protein kinase C activity by dextrorphan treatment in global ischemia. 768 73

Multiple processes lead to neuronal death after ischemia, but the generation of nitric oxide (NO) is a key component in this cascade of events. The mechanisms that regulate the extent of neuronal degeneration during anoxia and NO toxicity are multifactorial. Neuronal death may be modulated by the activity of signal transduction systems that influence the toxicity of NO or its metabolic products such as cGMP. The enzyme responsible for the production of NO, nitric oxide synthase (NOS), is phosphorylated by protein kinase C (PKC), the cAMP-dependent protein kinase (PKA), and the calcium/calmodulin-dependent protein kinase II (CaM-II). We examined in primary cultured hippocampal neurons whether the protein kinases PKC, PKA, CaM-II, and cGMP-dependent protein kinase modified the toxic effects of anoxia and NO. Down-regulation of PKC activity with PMA (1 microM) increased hippocampal neuronal survival during anoxia and NO exposure from approximately 22% to 88%. Inhibitors of PKC activity (H-7, H-8, sphingosine, and staurosporine) also were neuroprotective. Down-regulation of PKC activity increased survival during anoxia even in the presence of the NOS inhibitor, N omega-methyl-L-arginine. Thus, although down-regulation of PKC activity may increase neuronal survival by decreasing NOS activity, it also is likely that PKC contributes to ischemic neuronal death by mechanisms that are independent of NOS. Inhibition of the cGMP-dependent protein kinase activity, but not the activity of the CaM-II also was neuroprotective during NO administration. In contrast to the protective effects of inhibition of PKC and the cGMP-dependent protein kinase, activation rather than inhibition of PKA increased hippocampal neuronal survival during NO exposure. These results indicate that neuronal survival during anoxia and NO exposure is linked to the modulation of PKC, PKA, and cGMP-dependent protein kinase activity but is not dependent on the CaM-II pathway. Understanding the involvement of PKC, PKA, and the cGMP-dependent protein kinase in modulating the effect of neuronal death during ischemia and NO toxicity may help in directing future therapeutic modalities for cerebrovascular disease.
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PMID:Protein kinases modulate the sensitivity of hippocampal neurons to nitric oxide toxicity and anoxia. 823 Mar 23

[32P]Azido-purine analogs of ATP and GTP were used to detect changes in phosphorylation and nucleotide binding induced by ischemia and subsequent reperfusion in rat brain striatum, hippocampus and paramedian cortex (PM cortex) tissues. Major changes in phosphorylation were observed for a 130-kDa protein, tentatively identified as the Ca2+ transport ATPase, and calcium/calmodulin-dependent protein kinase II (CaM Kinase II) in all tissues. However, recovery of the phosphorylation of the 130-kDa protein occurred only in the PM cortex on reperfusion. A 200-300% increase in [32P]8N3ATP photoinsertions was observed in the striatum and hippocampus regions for a 43-kDa protein with an isoelectric point of 6.8. This protein was identified as glutamine synthetase (GS) and the increase in binding was found to be due to both increased copy number and activation by Mn2+. An increase in [32P]8N3GTP photoinsertion into a 55-kDa protein, identified as the beta-subunit of tubulin, was found only in the striatum and hippocampus. This indicates the depolymerization of microtubulin in these tissues. These changes correlate to the vulnerability of the striatum and hippocampus to ischemia-induced neuronal death.
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PMID:A comparison of changes in nucleotide-protein interactions in the striatal, hippocampus and paramedian cortex after cerebral ischemia and reperfusion: correlations to regional vulnerability. 922 22

We have previously reported the formation of calcium/calmodulin-dependent protein kinase II (CaMKII) clusters approximately 110 nm in diameter in hippocampal neurons in culture and in the intact adult brain, under conditions that simulate ischemic stress and increase [Ca(2+)](i) [Dosemeci et al. (2000) J. Neurosci. 20, 3076-3084; Tao-Cheng et al. (2001) Neuroscience 106, 69-78]. These observations suggest that ischemia-like conditions that prevail during the dissection of brain tissue for the preparation of hippocampal slices could lead to the formation of CaMKII clusters. We now show by pre-embedding immuno-electron microscopy that, indeed, CaMKII clusters are present in the CA1 pyramidal neurons in hippocampal slices from adult rats fixed immediately after dissection, and that the number of CaMKII clusters increases with the delay time between decapitation and fixation. Moreover, CaMKII clusters are typically localized near the endoplasmic reticulum. When acute slices are allowed to recover in oxygenated medium for 2 h, CaMKII clusters mostly disappear, indicating that clustering is reversible. Also, the postsynaptic density, another site for CaMKII accumulation under excitatory conditions, becomes thinner upon recovery. Treatment of recovered slices with high potassium for 90 s causes the re-appearance of CaMKII clusters in nearly all CA1 pyramidal cells examined. On the other hand, when dissociated hippocampal neurons in primary culture are exposed to the same depolarizing conditions, only approximately 25% of neurons exhibit CaMKII clusters, indicating a difference in the susceptibility of the neurons in culture and in acute slices to excitatory stimuli. Altogether these observations indicate that the effect of CaMKII clustering should be considered when interpreting experimental results obtained with hippocampal slices.
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PMID:Calcium/calmodulin-dependent protein kinase II clusters in adult rat hippocampal slices. 1242 9

To explore biochemical basis for cerebroprotective effect of immunosuppressant FK506, we studied changes in subcellular distribution of protein kinase C gamma (PKC gamma) as well as calcium/calmodulin-dependent protein kinase II (CaMKII) after ischemia. Male Mongolian gerbils were subjected to 5 min forebrain ischemia. FK506 (1 or 3 mg kg-1) was administered at 1 min after recirculation, which was confirmed to be cerebroprotective by histological examination at seven days after ischemia. At the designated time points (before ischemia, 5 min ischemia, 1 and 24 h recovery), heads were frozen and samples were taken from CA1 subfield of hippocampus. Western blot analysis was carried out. Persistent translocations of PKC gamma and CaMKII to synaptosomal P2 fraction were observed in vehicle-treated group. FK506 significantly decreased levels of PKC gamma and CaMKII in P2 fraction at 24 h of recovery. The present results suggest FK506 downregulates translocated PKC gamma and CaMKII, which may contribute to its survival promoting effect after cerebral ischemia.
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PMID:Effects of FK506 on the translocation of protein kinase C and CaM kinase II in the gerbil hippocampal CA1 neurons. 1286 2

The majority of hippocampal neurons in dissociated cultures and in intact brain exhibit clustering of calcium/calmodulin-dependent protein kinase II (CaMKII) into spherical structures with an average diameter of 110 nm when subjected to conditions that mimic ischemia and excitotoxicity [Neuroscience 106 (2001) 69]. Because clustering of CaMKII would reduce its effective concentration within the neuron, it may represent a cellular strategy to prevent excessive CaMKII-mediated phosphorylation during episodes of Ca2+ overload. Here we employ a relatively mild excitatory stimulus to promote sub-maximal clustering for the purpose of studying the conditions for the formation and disappearance of CaMKII clusters. Treatment with 30 microM N-methyl-D-aspartic acid (NMDA) for 2 min produced CaMKII clustering in approximately 15% of dissociated hippocampal neurons in culture, as observed by pre-embedding immunogold electron microscopy. These CaMKII clusters could be labeled with antibodies specific to the phospho form (Thr286) of CaMKII, suggesting that at least some of the CaMKII molecules in clusters are autophosphorylated. To test whether phosphorylation is involved in the formation and maintenance of CaMKII clusters, the phosphatase inhibitors calyculin A (5 nM) or okadaic acid (1 microM) were included in the incubation medium. With inhibitors more neurons exhibited CaMKII clusters in response to 2 min NMDA treatment. Furthermore, 5 min after the removal of NMDA and Ca2+, CaMKII clusters remained and could still be labeled with the phospho-specific antibody. In contrast, in the absence of phosphatase inhibitors, no clusters were detected 5 min after the removal of NMDA and Ca2+ from the medium. These results suggest that phosphatases type 1 and/or 2A regulate the formation and disappearance of CaMKII clusters.
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PMID:Inhibition of phosphatase activity facilitates the formation and maintenance of NMDA-induced calcium/calmodulin-dependent protein kinase II clusters in hippocampal neurons. 1559 Jan 49


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