title: Epidermal growth factor and phorbol ester regulate prolactin gene expression via distinct pathways.
abstract: Previous studies, involving phosphorylation of cytoplasmic proteins and localization of DNA regulatory elements, have suggested that epidermal growth factor (EGF) and 12-O-tetradecanoylphorbol-13-acetate (TPA) have similar actions on prolactin (PRL) gene expression by pituitary (GH) cells. However, little is presently known about whether the actions of these two factors involve common gene-distal intermediates. In the present study, we have employed two approaches to examine this question. Chronic exposure of GH3 cells to TPA, which strongly down-regulates protein kinase C activity, completely inhibited acute TPA stimulation of transient expression of a transfected PRL promoter construct ((-187)PRL-CAT), but did not inhibit EGF stimulation of either accumulation of endogenous PRL mRNA or of expression of (-187)PRL-CAT. Furthermore, the acute stimulatory effects of EGF and TPA on expression of (-187)PRL-CAT were additive. Each of these observations implies that EGF and TPA have gene-distal actions on PRL gene expression that are at least partially non-overlapping.
authors.affiliation: Department of Physiology and Biophysics, Mount Sinai School of Medicine of City University of New York, NY 10029.
authors.forename: A E
authors.initials: AE
authors.lastname: Jackson
authors.forename: S K
authors.initials: SK
authors.lastname: Bandyopadhyay
authors.forename: C
authors.initials: C
authors.lastname: Bancroft
mesh_terms: D000818:Animals; D002460:Cell Line; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism*; D011388:Prolactin / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000187:drug effects; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection
chemical_list: D004815:Epidermal Growth Factor; D011388:Prolactin; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate