title: Translocation and down-regulation of protein kinase C-alpha, -beta, and -gamma isoforms during ischemia-reperfusion in rat brain.
abstract: 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-delta and -epsilon isoforms were predominant in the P2 (synaptosome-rich) fraction, whereas PKC-alpha, -beta, -gamma, -epsilon, and -zeta isoforms were rich in the S (cytosolic) fraction. With time of ischemia (5-30 min), PKC-alpha, -beta, and -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-alpha and -gamma activities to a lesser extent. There was no redistribution of PKC-delta, -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-alpha from dimer to trimer, and the decrease in activity. These data show that PKC-alpha, -beta, and -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.
authors.affiliation: Department of Legal Medicine, Yamaguchi University School of Medicine, Ube, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Harada
authors.forename: T
authors.initials: T
authors.lastname: Maekawa
authors.forename: K M
authors.initials: KM
authors.lastname: Abu Shama
authors.forename: T
authors.initials: T
authors.lastname: Yamashima
authors.forename: K
authors.initials: K
authors.lastname: Yoshida
mesh_terms: D000818:Animals; D001921:Brain / Q000201:enzymology*; D002154:Calpain / Q000037:antagonists & inhibitors; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003600:Cytosol / Q000201:enzymology; D015971:Gene Expression Regulation, Enzymologic; D002546:Ischemic Attack, Transient / Q000201:enzymology*; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D008297:Male; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D064546:Protein Kinase C beta; D051571:Protein Kinase C-alpha; D051381:Rats; D017208:Rats, Wistar; D015424:Reperfusion; D013347:Subcellular Fractions / Q000201:enzymology; D013574:Synaptosomes / Q000201:enzymology; D013997:Time Factors
chemical_list: D015853:Cysteine Proteinase Inhibitors; D007527:Isoenzymes; C087857:protein kinase C gamma; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D051571:Protein Kinase C-alpha; D002154:Calpain