title: From gonadotropin-inhibitory hormone to SIFamides: are echinoderm SALMFamides the "missing link" in a bilaterian family of neuropeptides that regulate reproductive processes?
abstract: Gonadotropin-inhibitory hormone (GnIH) belongs to a family of vertebrate neuropeptides with a C-terminal PxRFamide motif, which exert effects by activating the G-protein coupled receptors NPFF1 and/or NPFF2. Comparative analysis of genome sequence data has revealed that orthologs of NPFF1/NPFF2-type receptors occur throughout the Bilateria and the neuropeptide ligand that activates the Drosophila NPFF1/NPFF2-type receptor has been identified as AYRKPPFNGSIFamide ("SIFamide"). Therefore, SIFamide-type neuropeptides, which occur throughout protostomian invertebrates, probably share a common evolutionary origin with vertebrate PxRFamide-type neuropeptides. Based on structural similarities, here SALMFamide neuropeptides are identified as candidate ligand components of this ancient bilaterian peptide-receptor signaling system in a deuterostomian invertebrate phylum, the echinoderms (e.g., starfish, sea urchins). Furthermore, functional studies provide evidence that PxRFamide/SALMFamide/SIFamide-type neuropeptides have evolutionarily conserved roles in regulation (typically inhibitory) of reproductive processes.
authors.affiliation: Queen Mary University of London, School of Biological & Chemical Sciences, Mile End Road, London E1 4NS, UK. Electronic address: M.R.Elphick@qmul.ac.uk.
authors.forename: Maurice R
authors.initials: MR
authors.lastname: Elphick
mesh_terms: D000818:Animals; D007028:Hypothalamic Hormones / Q000235:genetics / Q000378:metabolism; D007447:Invertebrate Hormones / Q000235:genetics / Q000378:metabolism; D009479:Neuropeptides / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D012098:Reproduction / Q000235:genetics / Q000502:physiology*
chemical_list: D007028:Hypothalamic Hormones; D007447:Invertebrate Hormones; D009479:Neuropeptides; C069624:SALMFamide 1; C069625:SALMFamide 2
keywords: FMRFamide; GnIH; NPFF; SALMFamide; SIFamide