CRF and cAMP regulation of POMC gene expression in corticotrophic tumor cells.
The effects of corticotropin releasing factor (CRF) on pro-opiomelanocortin (POMC) gene expression were investigated in an anterior pituitary corticotrophic tumor cell line, AtT-20/D16-16. The results of mRNA dot blot hybridization assays suggested that CRF, at a concentration of 10(-7) M, positively regulates the expression of the POMC gene in AtT-20 cells in a concentration-dependent fashion. Evaluation of the time course of this effect indicated that CRF had a biphasic mode of action. CRF and alpha-amanitin (inhibitor of RNA polymerase II activity) were also found to affect POMC mRNA levels in a concentration-dependent fashion. Eight-bromo-cyclic adenosine monophosphate (8-Br-cAMP) produced biphasic effects on POMC mRNA levels, supporting evidence of a role for cAMP as a second messenger in the regulation of POMC gene expression. It was also found that alpha-amanitin negatively regulated basal and CRF-stimulated POMC mRNA levels at both the 2 hr and 24 hr time periods, supporting evidence for positive regulation of POMC by CRF at the transcriptional level.
Knight
R M
RM
National Institute of Neurological and Communicative Disorders and Stroke, Bethesda, MD 20892.
Farah
J M
JM
Bishop
J F
JF
O'Donohue
T L
TL
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology*; D000324:Adrenocorticotropic Hormone; D000546:Amanitins / Q000494:pharmacology; D000818:Animals; D002460:Cell Line; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology*; D000242:Cyclic AMP / Q000502:physiology*; D005796:Genes / Q000187:drug effects*; D007700:Kinetics; D010911:Pituitary Neoplasms; D011333:Pro-Opiomelanocortin / Q000235:genetics*; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects*; D001615:beta-Endorphin / Q000378:metabolism
D000546:Amanitins; D012333:RNA, Messenger; D015124:8-Bromo Cyclic Adenosine Monophosphate; D001615:beta-Endorphin; D011333:Pro-Opiomelanocortin; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone; D000242:Cyclic AMP