Pituitary adenylate cyclase polypeptide (PACAP) stimulates cyclic AMP formation in pituitary fibroblasts and 3T3 tumor fibroblasts: lack of enhancement by protein kinase C activation.
A number of neuropeptides were shown to produce potent mitogenic effects on Swiss 3T3 fibroblasts by activating the phospholipase C pathway. Here we provide evidence for the activation by PACAP of the adenylate cyclase pathway in 3T3, as well as in non-tumoral pituitary fibroblasts, similarly to what was seen in pituitary endocrine cells. In these cells, PACAP triggered elevation of both intracellular and extracellular contents of cAMP and the effect was time- and dose-dependent, with half-maximal stimulations being induced with about 0.1 nM. Following activation of protein kinase C (PKC) by the phorbol ester phorbol 12-myristate 13-acetate (PMA), PACAP-induced cAMP production was amplified in pituitary endocrine cells, but was either unchanged or dampened in 3T3 and pituitary fibroblasts, respectively. Pretreatment of cells with pertussis toxin (PT) failed to change the effect of PMA on PACAP-stimulated adenylate cyclase activity, irrespective of the cell type being used. However, PT dramatically reduced the potentiation by PMA of cAMP production enhanced by forskolin in 3T3 cells. These results provide new evidence pointing to the presence in fibroblasts of receptors for PACAP, coupled to cAMP production, which may play a role in the modulation of the mitogenic signal. They also indicate that, compared with pituitary endocrine cells, PKC activation in fibroblasts differentially affected PACAP-induced cAMP formation and that these effects were unaltered upon inhibition by PT of Gi-like proteins.
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D016475:3T3 Cells / Q000187:drug effects* / Q000378:metabolism; D037361:Adenylate Cyclase Toxin; D000818:Animals; D002461:Cell Line, Transformed; D005576:Colforsin / Q000494:pharmacology; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology; D000242:Cyclic AMP / Q000096:biosynthesis*; D004789:Enzyme Activation / Q000187:drug effects; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D009479:Neuropeptides / Q000494:pharmacology*; D037342:Pertussis Toxin; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D010902:Pituitary Gland / Q000166:cytology; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013268:Stimulation, Chemical; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
C495402:Adcyap1 protein, mouse; C495403:Adcyap1 protein, rat; D037361:Adenylate Cyclase Toxin; D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D010566:Virulence Factors, Bordetella; D005576:Colforsin; D003346:Corticotropin-Releasing Hormone; D000242:Cyclic AMP; D037342:Pertussis Toxin; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D015056:1-Methyl-3-isobutylxanthine