Protein kinase C-mediated down-regulation of beta1-adrenergic receptor gene expression in rat C6 glioma cells.
In the current study, we investigated the mechanism by which protein kinase C (PKC) regulates the expression of beta1-adrenergic receptor (beta1AR) mRNA in rat C6 glioma cells. Exposure of the cells to 4beta-phorbol-12-myristate-13-acetate (PMA), an activator PKC, resulted in a down-regulation of both beta1AR binding sites and mRNA levels in a time- and concentration-dependent manner. This effect was not observed with phorbol esters that do not activate PKC and was blocked by bisindolylmaleimide, a specific PKC inhibitor. Activation of PKC did not reduce the half-life of beta1AR mRNA but significantly decreased the activity of the beta1AR promoter, as determined by reporter analysis. A putative response element, with partial homology to a consensus cAMP response element, was identified by mutation analysis of the promoter at positions -343 to -336, relative to the translational start site. Mutation of this putative regulatory element, referred to as a beta1AR-PKC response element, completely blocked the PKC-mediated down-regulation of beta1AR promoter activity. Gel mobility shift analysis detected two specific bands when C6 cell extracts were incubated with a labeled DNA probe containing the beta1AR-PKC response element sequence. Formation of one of these bands was inhibited by an oligonucleotide probe containing a consensus CRE and disrupted by an antibody for cAMP response element binding protein. Based on these studies, we propose that the PKC-induced down-regulation of beta1AR gene transcription in C6 cells is mediated in part by a cAMP response element binding protein-dependent mechanism acting on a novel response element.
Li
Z
Z
Division of Molecular Psychiatry, Departments of Psychiatry and Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06508, USA.
Vaidya
V A
VA
Alvaro
J D
JD
Iredale
P A
PA
Hsu
R
R
Hoffman
G
G
Fitzgerald
L
L
Curran
P K
PK
Machida
C A
CA
Fishman
P H
PH
Duman
R S
RS
D000818:Animals; D002273:Carcinogens / Q000494:pharmacology*; D000242:Cyclic AMP / Q000378:metabolism; D015536:Down-Regulation; D005910:Glioma / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000187:drug effects; D011493:Protein Kinase C / Q000378:metabolism*; D012333:RNA, Messenger / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D018342:Receptors, Adrenergic, beta-1 / Q000187:drug effects* / Q000235:genetics; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000187:drug effects
D002273:Carcinogens; D012333:RNA, Messenger; D018342:Receptors, Adrenergic, beta-1; D000242:Cyclic AMP; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate