Translocation and Down-Regulation of Protein Kinase C- sub( alpha ), beta , and - sub( gamma ) Isoforms During Ischemia-Reperfusion in Rat Brain

• Published in: Journal of neurochemistry Vol. 72; no. 6; pp. 2556 - 2564
• Main Authors: Harada, Kazuki, Maekawa, Tsuyoshi, Shama, KMA, Yamashima, Tetsumori, Yoshida, Ken-ichi
• Format: Journal Article
• Language: English
• Published: 01.06.1999
• ISSN: 0022-3042
• DOI: 10.1046/j.1471-4159.1999.0722556.x

We investigated the distribution of protein kinase C (PKC) isoforms in the subcellular fractions (P1, 1,000-g pellet; P2, 10,000-g pellet; P3, 100,000-g pellet; S, 100,000-g supernatant) of rat forebrain after ischemia or reperfusion by immunoblotting. PKC- sub( delta ) and - sub( epsilon ) isoforms were predominant in the P2 (synaptosome-rich) fraction, whereas PKC- sub( alpha ), - beta , - sub( gamma ), - sub( epsilon ), and - zeta isoforms were rich in the S (cytosolic) fraction. With time of ischemia (5-30 min), PKC- sub( alpha ), - beta , and - sub( gamma ) translocated to the P2 and P3 fractions, whereas reperfusion for 60 min after 30 min of ischemia reduced PKC- beta activity greatly and PKC- sub( alpha ) and - sub( gamma ) activities to a lesser extent. There was no redistribution of PKC- sub( delta ), - sub( epsilon ), and - zeta after ischemia or reperfusion. A calpain inhibitor, acetylleucylleucylnorleucinal, inhibited the down-regulation of PKC- beta , through intravenous injection. The PKC translocation to the P2 fraction was accompanied by their dephosphorylation, transition of PKC- sub( alpha ) from dimer to trimer, and the decrease in activity. These data show that PKC- sub( alpha ), - beta , and - sub( gamma ) isoforms translocate chiefly to the synaptosome in ischemic brain in association with the dephosphorylation, multimeric change, and inactivation, followed by the proteolysis of PKC- beta by calpain after postischemic reperfusion.