Protein kinase Cdelta mediates ethanol-induced up-regulation of L-type calcium channels.
Brief ethanol exposure inhibits L-type, voltage-gated calcium channels in neural cells, whereas chronic exposure increases the number of functional channels. In PC12 cells, this adaptive response is mediated by protein kinase C (PKC), but the PKC isozyme responsible is unknown. Since chronic ethanol exposure increases expression of PKCdelta and PKCepsilon, we investigated the role these isozymes play in up-regulation of L-type channels by ethanol. Incubation with the PKC inhibitor GF 109203X or expression of a PKCdelta fragment that inhibits phorbol ester-induced PKCdelta translocation largely prevented ethanol-induced increases in dihydropyridine binding and K+-stimulated 45Ca2+ uptake. A corresponding PKCepsilon fragment had no effect on this response. These findings indicate that PKCdelta mediates up-regulation of L-type channels by ethanol. Remaining responses to ethanol in cells expressing the PKCdelta fragment were not inhibited by GF 109203X, indicating that PKCdelta-independent mechanisms also contribute. PKCdelta overexpression increased binding sites for dihydropyridine and L-channel antagonists, but did not increase K+-stimulated 45Ca2+ uptake, possibly because of homeostatic responses that maintain base-line levels of channel function. Since L-type channels modulate drinking behavior and contribute to neuronal hyperexcitability during alcohol withdrawal, these findings suggest an important role for PKCdelta in alcohol consumption and dependence.
Gerstin
E H
EH
Department of Neurology, Ernest Gallo Clinic and Research Center, University of California, San Francisco, California 94110, USA.
McMahon
T
T
Dadgar
J
J
Messing
R O
RO
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000378:metabolism; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D020746:Calcium Channels, L-Type; D004791:Enzyme Inhibitors / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology*; D007211:Indoles / Q000494:pharmacology; D007527:Isoenzymes / Q000378:metabolism*; D017275:Isradipine / Q000378:metabolism; D008301:Maleimides / Q000494:pharmacology; D016716:PC12 Cells; D011188:Potassium / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051745:Protein Kinase C-delta; D051381:Rats; D015854:Up-Regulation
D000893:Anti-Inflammatory Agents; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D004791:Enzyme Inhibitors; D007211:Indoles; D007527:Isoenzymes; D008301:Maleimides; D000431:Ethanol; C497260:Prkcd protein, rat; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; C070515:bisindolylmaleimide I; D011188:Potassium; D017275:Isradipine