Human Relaxin Receptor RXFP1 Is Fully Functional in Mice

Presentation Number: SUN 272
Date of Presentation: April 2nd, 2017

Elena M Kaftanovskaya*1, Mariluz A Soula1, Courtney Myhr1, Brian A Ho1, Briana Cervantes1, Javier How1, Irina U Agoulnik1, Juan J. Marugan2 and Alexander I Agoulnik1
1Herbert Wertheim College of Medicine, Florida International University, Miami, FL, 2NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD


Relaxin, a small peptide hormone of insulin/relaxin family, has been shown to have antifibrotic, organ protective, vasodilatory, and pro-angiogenic properties in several animal models of human diseases and in clinical trials. Relaxin receptor is a G protein-coupled receptor RXFP1, relaxin family peptide receptor 1. We have identified a first series of small molecule allosteric RXFP1 agonists. Lead compound, ML290, demonstrated preferred ADME profiles; it is easy to synthesize and it has high stability in vivo. However, ML290 behaves as inverse allosteric agonist against mouse receptor in vitro. Therefore the effects of ML290 treatment cannot be tested in pre-clinical models in wild-type mice. Here we describe the production and analysis of a new mouse transgenic model, a knock-in/knockout of human RXFP1 (hRXFP1) cDNA into mouse Rxfp1 gene. Insertion of the targeting vector into mouse Rxfp1 locus caused a duplication of genomic DNA and a disruption of mouse gene expression. Quantitative RT-PCR showed that hRXFP1 had the same expression pattern as the endogenous mouse allele. Female mice hemizygous or homozygous for hRXFP1 allele showed relaxation of pubic symphysis at parturition, normal development of mammary nipples and cervical epithelium, thus indicating a full complementation of mouse Rxfp1 gene ablation. Intravenous injection of relaxin led to a rapid increase in heart rate in unconscious wild-type and humanized hRXFP1 females, but not in Rxfp1 deficient mice. The ML290 injection increased heart rate and decreased serum osmolality in humanized hRXFP1 but not in wild-type animals suggesting specific target engagement by small molecule agonist. Humanized RXFP1 mice can be used for testing relaxin receptor modulators in various preclinical studies.


Nothing to Disclose: EMK, MAS, CM, BAH, BC, JH, IUA, JJM, AIA