The relaxin family peptide receptors and their ligands : new developments and paradigms in the evolution from jawless fish to mammals

摘要: Relaxin family peptide receptors (Rxfps) and their ligands, relaxin (Rln) insulin-like (Insl) peptides, are broadly implicated in the regulation of reproductive neuroendocrine processes mammals. Most placental mammals harbour genes for four receptors, namely rxfp1, rxfp2, rxfp3 rxfp4. The number identity rxfps other vertebrates immensely variable, which is probably attributable to intraspecific variation regulation. Here, we highlight several interesting, but greatly overlooked, aspects rln/insl-rxfp evolutionary history: ancient origin, recruitment novel diverse roles selection, differential retention lineage-specific loss over time. tremendous diversity rln/insl rxfp appears have arisen from two divergent one ligand that were duplicated by whole genome duplications (WGD) early vertebrate evolution, although genes, notably mammals, also via small scale duplications. Duplication varied across lineages: teleosts retained more WGD-derived dominated those thought be involved (rln3, insl5 3/4 genes), while eutherian witnessed diversification rapid evolution reproduction (rln/insl3). Several arose history lost most and, a lesser extent, diverging tetrapods. To elaborate on history, provide updated phylogenies Rxfp1/2 Rxfp3/4 including new sequences taxa such as coelacanth, skate, spotted gar, lamprey. We summarize recent progress made towards understanding functional biology Rxfps non-mammalian taxa, providing conceptual framework research Rxfp signaling vertebrates.