Stapled B chain analogues of relaxin‐3 retain biological activity

• Published in: The FASEB journal Vol. 30; no. S1
• Main Authors: Dawe, Gavin Stewart, Jayakody, Tharindunee, Mawari, Subhi
• Format: Journal Article
• Language: English
• Published: 01-04-2016
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fasebj.30.1_supplement.lb512

Abstract only
Relaxin‐3, the most recently discovered member of the relaxin/insulin‐like family of peptides, is involved in regulating stress and anxiety, feeding, metabolism and cognition. Mature relaxin‐3 consists of two peptide chains (A and B) held together by disulphide bonds. Structure activity relationship studies have revealed that the relaxin‐3 B chain is more important in binding and activating the cognate receptor of relaxin‐3, relaxin/insulin‐like family peptide receptor 3 (RXFP3), than the A chain. Stapling renders peptide drugs less prone to proteolysis and can increase activity by locking the peptide conformation. We synthesized stapled B chains of relaxin‐3, hypothesizing that stapling mimics the function of the A chain in stabilizing the B chain and does not compromise activation of RXFP3. Relaxin‐3 B chain was stapled at the 14
th
and 18
th
positions or the 18
th
and 22
nd
positions by i and i+4 ring‐closing metathesis hydrocarbon stapling. In order to determine RXFP3 activation, we tested the peptides for cAMP inhibition and ERK1/2 activation. Both peptides significantly activated RXFP3 as observed in the inhibition of forskolin induced cAMP assay and ERK1/2 activation assay. We conclude that stapling of the relaxin‐3 B chain does not prevent its ability to activate RXFP3. Stapling of the relaxin‐3 B chain holds promise for development of stable peptide agonists and antagonists of RXFP3 to aid relaxin‐3/RXFP3 research.
Support or Funding Information
This work was supported by the Biomedical Research Council of Singapore (BMRC 10/1/21/19/645), the National Medical Research Council of Singapore (NMRC/1287/2011) and the Ministry of Education, Singapore, Academic Research Fund Tier 1 Seed Fund for Basic Science Research (T1‐BSRG 2014‐03).