Signalling profiles of H3 relaxin, H2 relaxin and R3(BΔ23-27)R/I5 acting at the relaxin family peptide receptor 3 (RXFP3)

Br J Pharmacol. 2014 Jun;171(11):2827-41. doi: 10.1111/bph.12623.

Abstract

Background and purpose: Relaxin family peptide receptor 3 (RXFP3) is expressed in brain areas important for processing sensory information and feeding, suggesting that it may be a target for anti-anxiety and anti-obesity drugs. We examined the effects of H3 relaxin, the biased agonist H2 relaxin and the antagonist, R3(BΔ23-27)R/I5, on RXFP3 signalling to establish their suitability as tools to assess the physiological roles of RXFP3.

Experimental approach: The signalling profile of the RXFP3 ligands was determined using reporter gene assays, multiplexed signalling assays and direct examination of receptor-G protein and receptor-β-arrestin interactions using BRET.

Key results: H2 relaxin activated p38MAPK and ERK1/2 with lower efficacy than H3 relaxin, but had similar efficacy for JNK1/2 phosphorylation. H2 or H3 relaxin activation of p38MAPK, JNK1/2 or ERK1/2 involved Pertussis toxin-sensitive G-proteins. R3(BΔ23-27)R/I5 blocked H3 relaxin AP-1 reporter gene activation, but not H2 relaxin AP-1 activation or H3 relaxin NF-κB activation. R3(BΔ23-27)R/I5 activated the SRE reporter, but did not inhibit either H2 or H3 relaxin SRE activation. R3(BΔ23-27)R/I5 blocked H3 relaxin-stimulated p38MAPK and ERK1/2 phosphorylation, but was a weak partial agonist for p38MAPK and ERK1/2 signalling. p38MAPK activation by R3(BΔ23-27)R/I5 was G protein-independent. H3 relaxin-activated RXFP3 interacts with Gαi2 , Gαi3 , Gαo A and Gαo B whereas H2 relaxin or R3(BΔ23-27)R/I5 induce interactions only with Gαi2 or Gαo B . Only H3 relaxin promoted RXFP3/β-arrestin interactions that were blocked by R3(BΔ23-27)R/I5.

Conclusion and implications: Understanding signalling profile of drugs acting at RXFP3 is essential for development of therapies targeting this receptor.

Keywords: R3(BΔ23-27)R/I5; RXFP3 signalling; relaxin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • CHO Cells
  • Cricetulus
  • Cyclic AMP / metabolism
  • Endopeptidases / genetics
  • Endopeptidases / metabolism
  • Humans
  • Mitogen-Activated Protein Kinases / metabolism
  • NF-kappa B / genetics
  • Receptors, G-Protein-Coupled / genetics
  • Receptors, G-Protein-Coupled / metabolism*
  • Relaxin / metabolism*
  • Serum Response Element / genetics
  • Transcription Factor AP-1 / genetics

Substances

  • Bacterial Proteins
  • NF-kappa B
  • RLN2 protein, human
  • RLN3 protein, human
  • RXFP3 protein, human
  • Receptors, G-Protein-Coupled
  • Transcription Factor AP-1
  • Relaxin
  • Cyclic AMP
  • Mitogen-Activated Protein Kinases
  • Endopeptidases
  • alkaline protease