Functional characterization of a receptor for vasoactive-intestinal-peptide-related peptides in cultured dermal melanophores from Xenopus laevis.
A receptor for vasoactive-intestinal-peptide (VIP)-related peptides was functionally characterized in a cell line derived from Xenopus melanophores using a recently described microtiter-plate-based bioassay. Activation of the melanophore VIP receptor by VIP or the peptides pituitary-adenylate-cyclase-activating polypeptide (PACAP 38), PACAP 27, and helodermin stimulated intracellular 3'-5' cyclic adenosine monophosphate (cAMP) accumulation and pigment dispersion in the cells. Helodermin, with an EC50 (concentration of peptide inducing half-maximal melanosome dispersion) of 46.5 pM, was the most potent activator of pigment dispersion, followed by PACAP 38 > VIP > PACAP 27. A similar order of potencies was observed for the peptides to induce cAMP accumulation. The responses to VIP agonists were selectively inhibited by the VIP antagonists PACAP-(6-27) and (N-Ac-Tyr(1)-D-Phe2)-growth-hormone-releasing factor[GRF](1-29)-NH2. Taken together, the results suggest that the melanophores express a VIP receptor that shares certain characteristics of, but also differs significantly from, other previously identified VIP receptors.
Marotti
L A
LA
The Interdepartmental Neuroscience Program, Yale University School of Medicine, USA.
Jayawickreme
C K
CK
Lerner
M R
MR
D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D020405:Dermis / Q000166:cytology; D006801:Humans; D008547:Melanophores / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D020460:Melanosomes / Q000502:physiology; D009479:Neuropeptides / Q000378:metabolism / Q000494:pharmacology; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D018005:Receptors, Vasoactive Intestinal Peptide / Q000378:metabolism*; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism / Q000494:pharmacology; D029867:Xenopus Proteins; D014982:Xenopus laevis
C495404:ADCYAP1 protein, Xenopus; C495401:ADCYAP1 protein, human; D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D018005:Receptors, Vasoactive Intestinal Peptide; D029867:Xenopus Proteins; D014660:Vasoactive Intestinal Peptide; D000242:Cyclic AMP