Ethanol regulates calcium channel subunits by protein kinase C delta -dependent and -independent mechanisms.
Chronic exposure to ethanol increases the number of functional L-type voltage-gated calcium channels in neural cells. In PC12 cells, this adaptive response is mediated by protein kinase C delta (PKCdelta), but the mechanisms by which this occurs are not known. Since expression of several different calcium channel subunits can increase the abundance of functional L-type channels, we sought to identify which subunits are regulated by ethanol. Incubation of PC12 cells with 120-150 mm ethanol for 6 days increased levels of alpha(1C), alpha(2), and beta(1b) subunit immunoreactivity in cell membranes and selectively increased the abundance of mRNA encoding the alpha(1C-1) splice variant of alpha(1C). In cells expressing a fragment of PKCdelta (deltaV1) that selectively inhibits PKCdelta, there was no increase in membrane-associated alpha(1C), alpha(2), and beta(1b) immunoreactivity following chronic ethanol exposure. However, ethanol still increased levels of alpha(1C-1) mRNA in these cells. These results indicate that ethanol increases the abundance of L-type channels by at least two mechanisms; one involves increases in mRNA encoding a splice variant of alpha(1C) and the other is post-transcriptional, rate-limiting, and requires PKCdelta.
Walter
H J
HJ
Department of Neurology and the Graduate Programs in Neuroscience and Biomedical Sciences, University of California, San Francisco 94143, USA.
McMahon
T
T
Dadgar
J
J
Wang
D
D
Messing
R O
RO
D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D020746:Calcium Channels, L-Type / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000494:pharmacology*; D007527:Isoenzymes / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D008969:Molecular Sequence Data; D016716:PC12 Cells; D011493:Protein Kinase C / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D051745:Protein Kinase C-delta; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012260:Ribonucleases / Q000378:metabolism; D013997:Time Factors; D015854:Up-Regulation
D020746:Calcium Channels, L-Type; D017931:DNA Primers; D018076:DNA, Complementary; D007527:Isoenzymes; D012333:RNA, Messenger; D000431:Ethanol; C497260:Prkcd protein, rat; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; D012260:Ribonucleases