Competitive binding of postsynaptic density 95 and Ca2+-calmodulin dependent protein kinase II to N-methyl-D-aspartate receptor subunit 2B in rat brain.

AIM

To investigate the interactions among postsynaptic density 95 (PSD-95), Ca2+-calmodulin dependent protein kinase IIalpha (CaMKIIalpha), and N-methyl-D-aspartate receptor subunit 2B (NR2B) during ischemia and reperfusion in hippocampus of rats.

METHODS

Brain ischemia was induced by four-vessel occlusion procedure in rats. Immunoprecipitation and immunoblotting were performed to study the interactions and phosphorylation of proteins. The association-dissociation of PSD-95 and CaMKIIalpha to and from N-methyl-D-aspartate (NMDA) receptor induced by ischemia and reperfusion and the effects of 1-[N,O-bis-(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenyl-piperazine (KN-62, a selective inhibitor of CaMKII) on these protein interactions were investigated. Coimmunoprecipitation and immunoblotting were performed for the studies of interactions among proteins.

RESULTS

The alternations of the binding level of PSD-95 and CaMKIIalpha to NR2B during ischemia and reperfusion demonstrated the negative correlation to each other. Pre-administration of KN62 through both cerebral ventricles inhibited the 10 min ischemia-induced increase of the binding of PSD-95 to NR2B and, on the contrary, promoted the binding of CaMKIIalpha to NR2B.

CONCLUSION

PSD-95 competes with CaMKII to bind to NR2B during ischemia and reperfusion in rat hippocampus.