Stimulation of extracellular signal-regulated kinase by pituitary adenylate cyclase-activating polypeptide in alpha T3-1 gonadotrophs.
The putative hypophysiotropic factor pituitary adenylate cyclase-activating polypeptide (PACAP) stimulates glycoprotein hormone alpha-subunit (alpha GSU) gene transcription and secretion in the clonal gonadotroph alpha T3-1 cell line. The specific signalling pathways regulating these actions of PACAP have not been clearly defined. We have examined the possibility that mitogen activated protein kinases (MAPKs) may play a role in mediating the effects of PACAP on alpha T3-1 gonadotrophs. Treatment of alpha T3-1 cells with PACAP (100 nM) or epidermal growth factor (EGF, 10 nM) for 5 min significantly stimulated extracellular signal-regulated kinase activity (ERK, a component of the MAPK pathway) as determined by an immunocomplex assay. Pre-treatment of alpha T3-1 cells with the specific MAPK kinase (MEK) inhibitor, U0126, blocked PACAP and EGF-induced activation of ERK. Transcriptional stimulation of a human alpha GSU-luciferase reporter construct by PACAP was unaffected by U0126 treatment. However, pre-treatment with U0126 significantly inhibited PACAP stimulation of [(3)H]-thymidine incorporation in alpha T3-1 cells. Thus our results suggest that PACAP stimulates ERK activation in alpha T3-1 cells, and that the functional effect of this ERK activation is increased DNA synthesis and cell proliferation rather then transcriptional activation of the alpha GSU gene.
Fowkes
R C
RC
Department of Endocrinology, St Bartholomew's & the Royal London School of Medicine & Dentistry, Queen Mary, University of London, London EC1A 7BE, UK. r.c.fowkes@mds.qmw.ac.uk
Burch
J
J
Burrin
J M
JM
D000818:Animals; D002070:Butadienes / Q000494:pharmacology; D018929:Cell Culture Techniques; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009479:Neuropeptides / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009570:Nitriles / Q000494:pharmacology; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology
C495402:Adcyap1 protein, mouse; D002070:Butadienes; D004791:Enzyme Inhibitors; D009479:Neuropeptides; D009570:Nitriles; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; C113580:U 0126; D020928:Mitogen-Activated Protein Kinases