Phorbol ester and calcium regulation of corticotrophin-releasing factor receptor 1 expression in a neuronal cell line.
We have previously demonstrated that corticotrophin-releasing factor receptor 1 (CRF-R1) mRNA levels can be down-regulated via activation of the cyclic AMP pathway in CATH.a cells, a neuronal cell line. In this study, we show evidence for down-regulation of CRF-R1 mRNA levels via activation of the protein kinase C (PKC) and calcium second messenger pathways. Incubation of CATH.a cells with phorbol 12-myristate 13-acetate (PMA), an activator of PKC, resulted in a time- and concentration-dependent down-regulation of CRF-R1 mRNA levels. Pretreatment with the inactive phorbol ester 4alpha-phorbol failed to influence significantly CRF-R1 mRNA levels. Incubation with carbachol, a cholinergic agonist known to activate PKC and increase intracellular calcium levels via phosphatidylinositol breakdown, also down-regulated CRF-R1 mRNA levels. Intracellular calcium levels were directly increased using A23187, a calcium ionophore, and thapsigargin, a calcium-ATPase inhibitor. Elevation of intracellular calcium content using either A23187 or thapsigargin significantly down-regulated levels of CRF-R1 mRNA. Furthermore, chelation of calcium with EGTA or blockade of voltage-dependent calcium channels with nifedipine inhibited agonist-mediated down-regulation of CRF-R1 mRNA levels. These results indicate that activation of PKC or calcium signal transduction pathways is sufficient to cause down-regulation of CRF-R1 mRNA levels and that calcium is required for agonist-mediated down-regulation of this receptor.
Iredale
P A
PA
Department of Psychiatry, Connecticut Mental Health Center, Yale University School of Medicine, New Haven 06508, U.S.A.
Bundey
R
R
Duman
R S
RS
D000470:Alkaloids; D000818:Animals; D053119:Benzophenanthridines; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D002460:Cell Line; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects; D004533:Egtazic Acid / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007700:Kinetics; D051379:Mice; D009543:Nifedipine / Q000494:pharmacology; D010617:Phenanthridines / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D018019:Receptors, Corticotropin-Releasing Hormone / Q000096:biosynthesis*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D019284:Thapsigargin / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects*; D000099052:CRF Receptor, Type 1
D000470:Alkaloids; D053119:Benzophenanthridines; D004791:Enzyme Inhibitors; D010617:Phenanthridines; D012333:RNA, Messenger; D018019:Receptors, Corticotropin-Releasing Hormone; D000001:Calcimycin; D004533:Egtazic Acid; D000099052:CRF Receptor, Type 1; D019284:Thapsigargin; D002217:Carbachol; D003346:Corticotropin-Releasing Hormone; C016299:chelerythrine; D011493:Protein Kinase C; D009543:Nifedipine; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium