Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.17 (CaMKII)
 4,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Reversible spinal cord ischemia in rabbits induced a rapid loss of Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) activity measured as incorporation of phosphate into exogenous substrates. About 70% of the activity was lost from the cytosolic fraction of spinal cord homogenates after 15 min of ischemia preceding irreversible paraplegia, which takes 25 min in this model. The loss of enzyme activity correlated with a loss of in situ renaturable autophosphorylation activity and a loss of CaM kinase II alpha and beta subunits in the cytosol detected by immunoblotting. CaM kinase II activity in the particulate fraction also decreased but the protein levels of the alpha and beta subunits increased. Thus ischemia resulted in an inactivation of CaM kinase II and a sequential or concurrent subcellular redistribution of the enzyme. However, denaturation and renaturation in situ of the CaM kinase subunits immobilized on membranes partly reversed the apparent inactivation of the enzyme in the particulate fraction. CaM kinase II activity was restored after reperfusion following short (< or = 25 min) durations of ischemia but not after longer durations (60 min) that result in irreversible paraplegia. The ischemia-induced inactivation of CaM kinase II, which phosphorylates proteins regulating many cellular processes, may be important in the cascade of events leading to delayed neuronal cell death.
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PMID:Inactivation and subcellular redistribution of Ca2+/calmodulin-dependent protein kinase II following spinal cord ischemia. 839 89

The microtubule-associated protein tau plays an important role in the dynamics of microtubule assembly necessary for axonal growth and neurite plasticity. Ischemia disrupts the neuronal cytoskeleton both by promoting proteolysis of its components and by affecting kinase and phosphatase activities that alter its assembly. In this study the effect of ischemia and reperfusion on the expression and phosphorylation of tau was examined in a reversible model of spinal cord ischemia in rabbits. tau was found to be dephosphorylated in response to ischemia with a time course that closely matched the production of permanent paraplegia. Dephosphorylation of tau was limited to the caudal lumbar spinal cord. In a similar manner, Ca2+/calmodulin-dependent kinase II activity was reduced only in the ischemic region. Thus, dephosphorylation of tau is an early marker of ischemia as is the rapid loss of Ca2+/calmodulin-dependent kinase II activity. tau, however, was rephosphorylated rapidly during reperfusion at site(s) that cause a reduction in its electrophoretic mobility regardless of the neurological outcome. Alterations in phosphorylation or degradation of tau may affect microtubule stability, possibly contributing to disruption of axonal transport but also facilitating neurite plasticity in a regenerative response.
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PMID:Changes in phosphorylation of tau during ischemia and reperfusion in the rabbit spinal cord. 852 66