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Changes in Phosphorylation of τ During Ischemia and Reperfusion in the Rabbit Spinal Cord
Author(s) -
Shackelford Deborah A.,
Nelson Kevin E.
Publication year - 1996
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1996.66010286.x
Subject(s) - dephosphorylation , ischemia , phosphorylation , neurite , microbiology and biotechnology , kinase , phosphatase , spinal cord , biology , microtubule , cytoskeleton , neuroscience , chemistry , medicine , biochemistry , cell , in vitro
The microtubule‐associated protein τ 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 τ was examined in a reversible model of spinal cord ischemia in rabbits. τ was found to be dephosphorylated in response to ischemia with a time course that closely matched the production of permanent paraplegia. Dephosphorylation of τ was limited to the caudal lumbar spinal cord. In a similar manner, Ca 2+ /calmodulin‐dependent kinase II activity was reduced only in the ischemic region. Thus, dephosphorylation of τ is an early marker of ischemia as is the rapid loss of Ca 2+ /calmodulin‐dependent kinase II activity, τ, 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 τ may affect microtubule stability, possibly contributing to disruption of axonal transport but also facilitating neurite plasticity in a regenerative response.