Original Article

Brain ischemia induces serine phosphorylation of neuronal nitric oxide synthase by Ca(2+)/calmodulin-dependent protein kinase II in rat hippocampus

Authors: Xue-bo YAN, Fan-jie MENG, Bo SONG, Guang-yi ZHANG

Abstract

AIM:
To investigate whether brain ischemia induces serine phosphorylation of neuronal nitric oxide synthase (nNOS) by Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and the interaction between CaMKII? and nNOS in rat hippocampus.
METHODS:
Brain ischemia was induced by bilateral carotid artery occlusion procedure. Phosphorylation and the interaction of proteins were studied by immunoprecipitation and immunoblotting. We investigated during brain ischemia serine phosphorylation and amount of nNOS in crude membranes fraction (P) and cytosolic fraction (S), interaction between CaMKIIalpha and nNOS, and the effects of 1-[N,O-bis-(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazine (KN-62, a selective inhibitor of CaMKII) on phosphorylation and the interaction of proteins in P.
RESULTS:
Serine phosphorylation of nNOS in P increased persistently during brain ischemia, and 15 min ischemia-induced serine phosphorylation of nNOS was attenuated significantly by KN-62. But there was no serine phosphorylation of nNOS in S. The distributions of nNOS were not affected by ischemia and KN-62. However, the binding levels of both CaMKIIalpha with nNOS and Thr(286) autophosphorylated CaMKIIalpha with nNOS increased after ischemia, and were diminished by KN-62.
CONCLUSION:
CaMKII interacted with nNOS and regulated serine phosphorylation of nNOS during brain ischemia.
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