Differential isoform-specific regulation of calcium-independent protein kinase C in rat cerebral cortex.
Regulation of the Ca(2+)-independent protein kinase C (PKC) activity and isoforms by phorbol esters was investigated in rat cerebral cortex. Loss of soluble PKC eta immunoreactivity from the soluble fraction was dramatic with only a small increase in the membrane fraction. The kinetics of PKC epsilon and -delta translocation were slower than that for PKC eta, while phorbol esters had no effect on PKC zeta translocation. Despite the translocation of PKC delta, -epsilon and -eta from the soluble to the membrane fraction, both fractions showed a loss of PKC activity. These data indicate that the rates of translocation, inactivation and/or downregulation appear to be different not only among these Ca(2+)-independent isozymes, but also from that reported for the Ca(2+)-dependent PKCs. In addition, these results emphasize the importance of measuring both Ca(2+)-independent PKC activity and immunoreactivity in evaluating activation of these isoforms.
Pascale
A
A
Institute of Pharmacological Sciences, University of Milano, Italy.
Fortino
I
I
Govoni
S
S
Trabucchi
M
M
Wetsel
W C
WC
Battaini
F
F
D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000201:enzymology*; D015536:Down-Regulation; D004789:Enzyme Activation / Q000502:physiology; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000096:biosynthesis / Q000378:metabolism*; D008297:Male; D010703:Phorbol Esters / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D011493:Protein Kinase C / Q000096:biosynthesis / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D007527:Isoenzymes; D010703:Phorbol Esters; D011189:Potassium Chloride; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium