title: Novel splice variants of type I pituitary adenylate cyclase-activating polypeptide receptor in frog exhibit altered adenylate cyclase stimulation and differential relative abundance.
abstract: Pituitary adenylate cyclase-activating polypeptide (PACAP) exerts its various effects through activation of two types of G protein-coupled receptors, a receptor with high affinity for PACAP named PAC1-R and two receptors exhibiting similar affinity for both PACAP and vasoactive intestinal polypeptide named VPAC1-R and VPAC2-R. Here, we report the characterization of PAC1-R and novel splice variants in the frog Rana ridibunda. The frog PAC1-R has 78% homology with human PAC1-R and is highly expressed in the central nervous system. Two splice variants of the frog receptor that display additional amino acid cassettes in the third intracellular loop were characterized. PAC1-R25 carries a 25-amino acid insertion that matches the hop cassette of the mammalian receptor, whereas PAC1-R41 carries a cassette with no homology to any mammalian PAC1-R variant. A third splice variant of PAC1-R, exhibiting a completely different intracellular C-terminal domain, named PAC1-Rmc has also been identified. Determination of cAMP formation in cells transfected with the cloned receptors showed that PACAP activated PAC1-R, PAC1-R25, and PAC1-R41 with similar potency. In contrast, PACAP failed to stimulate adenylate cyclase in cells transfected with PAC1-Rmc. Fusion of PAC1-R or PAC1-Rmc with the green fluorescent protein revealed that both receptors are expressed and targeted to the plasma membrane in transfected cells. The different PAC1-R variants are highly expressed in the frog brain and spinal cord and to a lesser extent in peripheral tissues, where only certain isoforms could be detected. The present data indicate that in frog, PACAP may act through different PAC1-R splice variants that differ in their G(s) protein coupling and their abundance in various tissues.
authors.affiliation: European Institute for Peptide Research (IFRMP 23), Laboratory of Cellular and Molecular Neuroendocrinology, Institut National de la Santé et de la Recherche Médicale, University of Rouen, 76821 Mont Saint Aignan, France.
authors.forename: David
authors.initials: D
authors.lastname: Alexandre
authors.forename: Hubert
authors.initials: H
authors.lastname: Vaudry
authors.forename: Luca
authors.initials: L
authors.lastname: Grumolato
authors.forename: Valérie
authors.initials: V
authors.lastname: Turquier
authors.forename: Alain
authors.initials: A
authors.lastname: Fournier
authors.forename: Sylvie
authors.initials: S
authors.lastname: Jégou
authors.forename: Youssef
authors.initials: Y
authors.lastname: Anouar
mesh_terms: D000262:Adenylyl Cyclases / Q000502:physiology*; D017398:Alternative Splicing / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D015139:Blotting, Southern; D001923:Brain Chemistry / Q000235:genetics; D003001:Cloning, Molecular; D000242:Cyclic AMP / Q000378:metabolism; D017403:In Situ Hybridization; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D009479:Neuropeptides / Q000494:pharmacology / Q000502:physiology; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D010957:Plasmids / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D011895:Rana ridibunda; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D051237:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I; D011979:Receptors, Pituitary Hormone / Q000187:drug effects / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014018:Tissue Distribution; D014162:Transfection
chemical_list: D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D012333:RNA, Messenger; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D051237:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I; D011979:Receptors, Pituitary Hormone; D000242:Cyclic AMP; D000262:Adenylyl Cyclases