Pituitary adenylate cyclase activating polypeptide induces multiple signaling pathways in rat peritoneal mast cells.
Pituitary adenylate cyclase activating polypeptide (PACAP) is a high-affinity ligand for at least two types of G-protein coupled receptors, the PACAP type 1 and type 2 receptor. In this study it is demonstrated that the C-terminal PACAP-fragment PACAP(6-27) stimulates serotonin release from rat peritoneal mast cells with higher potency (EC50: 0.2 vs. 2.0 microM) than the PACAP receptor ligand PACAP(1-27). PACAP-induced degranulation of rat peritoneal mast cells was abolished by pertussis toxin and by benzalkonium chloride (IC50: 9.1 microg/ml) indicating the involvement of heterotrimeric G-proteins of the Gi-type. The PACAP effect was also reduced by inhibitors of the phosphatidylinositol specific phospholipase C ((U73122), IC50: 4 microM; (ET-18-O-CH3), IC50: 18 microM), by D609, a specific inhibitor of the phosphatidylcholine specific phospholipase C (IC50: 41 microM), by the protein kinase C-inhibitor staurosporine (IC50: 0.6 microM) and by the lipoxygenase inhibitor nordihydroguaiaretic acid (NGDA) but not by indomethacin. It is concluded that PACAP peptides stimulate secretion in rat peritoneal mast cells in a PACAP receptor-independent manner, probably via direct activation of heterotrimeric G-proteins of the Gi-type; these G-proteins may lead to a sequential activation of different signaling cascades (see above), which may converge at the level of one or more staurosporine-sensitive protein kinase.
Department of Pharmacology, Christian-Albrechts University of Kiel, Germany. jseebeck@pharmakologie.uni-kiel.de
J
J
Seebeck
M L
ML
Kruse
A
A
Schmidt-Choudhury
J
J
Schmidtmayer
W E
WE
Schmidt
D037361:Adenylate Cyclase Toxin; D000818:Animals; D001952:Bridged-Ring Compounds / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D009637:Masoprocol / Q000494:pharmacology; D008407:Mast Cells / Q000187:drug effects* / Q000378:metabolism; D009479:Neuropeptides / Q000494:pharmacology*; D009636:Norbornanes; D010529:Peritoneal Cavity / Q000166:cytology*; D037342:Pertussis Toxin; D010742:Phospholipid Ethers / Q000494:pharmacology; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011760:Pyrrolidinones / Q000494:pharmacology; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects*; D019311:Staurosporine / Q000494:pharmacology; D013859:Thiocarbamates; D013871:Thiones / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D003189:p-Methoxy-N-methylphenethylamine / Q000494:pharmacology
C495403:Adcyap1 protein, rat; D037361:Adenylate Cyclase Toxin; D001952:Bridged-Ring Compounds; D004963:Estrenes; D009479:Neuropeptides; D009636:Norbornanes; D010742:Phospholipid Ethers; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011760:Pyrrolidinones; D013859:Thiocarbamates; D013871:Thiones; D010566:Virulence Factors, Bordetella; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C074854:U 73343; C026659:edelfosine; D003189:p-Methoxy-N-methylphenethylamine; C046498:tricyclodecane-9-yl-xanthogenate; D009637:Masoprocol; D037342:Pertussis Toxin; D019311:Staurosporine; D007213:Indomethacin