title: Identification of relaxin-3/INSL7 as a ligand for GPCR142.
abstract: We have recently identified the insulin-like peptide relaxin-3 (aka INSL7) as the endogenous ligand for an orphan G-protein-coupled receptor, GPCR135 (aka somatostatin- and angiotensin-like peptide receptor). Analysis of possible receptors related to GPCR135 revealed a single orphan receptor, GPCR142. Thus, we tested whether GPCR142 could also respond to relaxin-3 or related insulin-like molecules. Surprisingly, GPCR142 was activated by nanomolar concentrations of relaxin-3 but was completely unresponsive to all other known insulin-like peptides. We evaluated by reverse transcriptase-PCR the expression of GPCR142 mRNA in a variety of human tissues and found expression in brain, kidney, testis, thymus, placenta, prostate, salivary gland, thyroid, and colon. In an analysis of other species, we were able to find a full-length mouse homolog of GPCR142, but were unable to detect any complete GPCR142 transcripts in rat. With respect to intracellular signaling, GPCR142 is similar to GPCR135 in that it potently inhibits adenylate cyclase and stimulates 35S-GTPgammaS incorporation in response to relaxin-3. However, whereas GPCR135 signaling could be converted to calcium mobilization using a Gqi5 or Galpha16 G-proteins, GPCR142 was only capable of functioning in the presence of Galpha16. In the accompanying article (Liu, C., Eriste, E., Sutton, S., Chen, J., Roland, B., Kuei, C., Farmer, N., Jörnvall, H., Sillard, R., and Lovenberg, T. W. (2003) J. Biol. Chem. 278, 50754-50764), we present the case that relaxin-3, which has previously been shown to bind to the relaxin receptor LGR7, is most likely the endogenous ligand for GPCR135. In this report, we show an additional receptor, GPCR142, which is also selectively activated by relaxin-3. However, the anatomical localization of GPCR142 suggests that GPCR142 may have different physiological functions.
authors.affiliation: Johnson & Johnson Pharmaceutical Research and Development, L.L.C., San Diego, California 92121, USA. cliu9@prdus.jnj.com
authors.forename: Changlu
authors.initials: C
authors.lastname: Liu
authors.forename: Jingcai
authors.initials: J
authors.lastname: Chen
authors.forename: Steven
authors.initials: S
authors.lastname: Sutton
authors.forename: Barbara
authors.initials: B
authors.lastname: Roland
authors.forename: Chester
authors.initials: C
authors.lastname: Kuei
authors.forename: Niven
authors.initials: N
authors.lastname: Farmer
authors.forename: Rannar
authors.initials: R
authors.lastname: Sillard
authors.forename: Timothy W
authors.initials: TW
authors.lastname: Lovenberg
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D019556:COS Cells; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D003001:Cloning, Molecular; D006224:Cricetinae; D000242:Cyclic AMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006801:Humans; D008024:Ligands; D051379:Mice; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000502:physiology*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry* / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism / Q000502:physiology*; D018000:Receptors, Peptide / Q000737:chemistry* / Q000378:metabolism* / Q000502:physiology; D012065:Relaxin / Q000737:chemistry / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013552:Swine; D014018:Tissue Distribution; D014466:Ultraviolet Rays
chemical_list: D008024:Ligands; D009419:Nerve Tissue Proteins; C466742:RLN3 protein, rat; D012333:RNA, Messenger; C410092:RXFP3 protein, human; C480239:RXFP4 protein, human; D018160:Receptors, Cytoplasmic and Nuclear; D043562:Receptors, G-Protein-Coupled; D018000:Receptors, Peptide; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D012065:Relaxin; D000242:Cyclic AMP; D002118:Calcium