CDB15:0001302 RLN3 — RXFP3
Experimentally validated in Human, Mixed species; Orthology-inferred in Human, Mouse, Rat, Frog, Zebrafish, Macaque, Pig, Dog, Cow, Chimp, Horse, Marmoset, Sheep
Title
Journal:; Year Published:
Abstract
Pharmacological characterization of relaxin-3/INSL7 receptors GPCR135 and GPCR142 from different mammalian species.
The Journal of pharmacology and experimental therapeutics, 2005; PubMed, Homo sapiens RLN3 — Homo sapiens RXFP3
ABSTRACT: Relaxin-3 has recently been identified as a ligand for two structurally related G-protein-coupled receptors, human GPCR135 and GPCR142. This current study reports the characterization of mouse and rat GPCR135 as well as GPCR142 from mouse, monkey, cow, and pig at the molecular and pharmacological levels. Mouse and rat GPCR135 exhibit high homology (>85%) to the human GPCR135 and have very similar pharmacological properties to that of the human GPCR135. Human and mouse/rat relaxin-3 both bind to and activate mouse, rat, and human GPCR135 at high affinity with IC(50) or EC(50) values close to 0.5 nM. In contrast, the mouse GPCR142 is less well conserved (74% homology) with human GPCR142. The rat GPCR142 gene was found to be a pseudogene. We further cloned GPCR142 genes from monkey, cow, and pig and found that they are highly homologous (>84%) to human GPCR142. Pharmacological characterization of GPCR142 from different species demonstrated that relaxin-3 binds to GPCR142 from different species at high affinity (IC(50) < 5 nM). However, relaxin-3 does not stimulate a Ca(2+) response in cells coexpressing Galpha(16) and mouse GPCR142, whereas it does for cells expressing GPCR142 from other species tested. Our results suggest that GPCR142 may have a diminished role as a receptor for relaxin-3 in rodents, or perhaps GPCR142 functions as a receptor for another ligand in nonrodents. Boels and Schaller recently reported bradykinin as a ligand for GPCR142 (also known as GPR100). In this report, we demonstrate that bradykinin activates neither GPCR135 nor GPCR142, whereas relaxin-3 does.
Relaxin-3: improved synthesis strategy and demonstration of its high-affinity interaction with the relaxin receptor LGR7 both in vitro and in vivo.
Biochemistry, 2006; PubMed, Homo sapiens RLN3 — Homo sapiens RXFP3
ABSTRACT: Relaxin-3 is a member of the human relaxin peptide family, the gene for which, RLN3, is predominantly expressed in the brain. Mapping studies in the rodent indicate a highly developed network of RLN3, RLN1, and relaxin receptor-expressing cells in the brain, suggesting that relaxin peptides have important functional roles in the central nervous system. A regioselective disulfide-bond synthesis protocol was developed and used for the chemical synthesis of human (H3) relaxin-3. The selectively S-protected A and B chains were combined by stepwise formation of each of the three insulin-like disulfides via aeration, thioloysis, and iodolysis. Judicious positioning of the three sets of S-protecting groups was crucial for acquisition of synthetic H3 relaxin in a good overall yield. The activity of the peptide was tested against relaxin family peptide receptors. Although the highest activity was demonstrated on the human relaxin-3 receptor (GPCR135), the peptide also showed high activity on relaxin receptors (LGR7) from various species and variable activity on the INSL3 receptor (LGR8). Recombinant mouse prorelaxin-3 demonstrated similar activity to H3 relaxin, suggesting that the presence of the C peptide did not influence the conformation of the active site. H3 relaxin was also able to activate native LGR7 receptors. It stimulated increased MMP-2 expression in LGR7-expressing rat ventricular fibroblasts in a dose-dependent manner and, following infusion into the lateral ventricle of the brain, stimulated water drinking in rats, activating LGR7 receptors located in the subfornical organ. Thus, H3 relaxin is able to interact with the relaxin receptor LGR7 both in vitro and in vivo.