A novel tachykinin‐related peptide receptor

Abstract

Structurally tachykinin-related peptides have been isolated from various invertebrate species and shown to exhibit their biological activities through a G-protein-coupled receptor (GPCR) for a tachykinin-related peptide. In this paper, we report the identification of a novel tachykinin-related peptide receptor, the urechistachykinin receptor (UTKR) from the echiuroid worm, Urechis unitinctus. The deduced UTKR precursor includes seven transmembrane domains and typical sites for mammalian tachykinin receptors and invertebrate tachykinin-related peptide receptors. A functional analysis of the UTKR expressed in Xenopus oocytes demonstrated that UTKR, like tachykinin receptors and tachykinin-related peptide receptors, activates calciumdependent signal transduction upon binding to its endogenous ligands, urechistachykinins (Uru-TKs) IÀV and VII, which were isolated as Urechis tachykinin-related peptides from the nervous tissue of the Urechis unitinctus in our previous study. UTKR responded to all Uru-TKs equivalently, showing that UTKR possesses no selective affinity with Uru-TKs. In contrast, UTKR was not activated by substance P or an Uru-TK analog containing a C-terminal Met-NH 2 instead of Arg-NH 2 . Furthermore, the genomic analysis revealed that the UTKR gene, like mammalian tachykinin receptor genes, consists of five exons interrupted by four introns, and all the intron-inserted positions are completely compatible with those of mammalian tachykinin receptor genes. These results suggest that mammalian tachykinin receptors and invertebrate tachykinin-related peptide receptors were evolved from a common ancestral GPCR gene. This is the first identification of an invertebrate tachykinin-related peptide receptor from other species than insects and also of the genomic structure of a tachykininrelated peptide receptor gene.

Tachykinins: Neuropeptides That Are Ancient, Diverse, Widespread and Functionally Pleiotropic

“…In many insects, receptors of both DTKR- and NTLR-type have been identified (Jiang et al, 2013). In other invertebrates, such as for instance annelids ( Urechis ) and mollusks ( Octopus ) only receptors of DTKR type are known (Kawada et al, 2002; Kanda et al, 2007), suggesting that the NTL signaling system arose in the arthropod lineage (Jiang et al, 2013). However, TK-like precursors with NTL-like peptides are found in the spider mite (chelicerate) as well as tardigrades; the latter suggesting that the NTL signaling might also be present outside arthropods.…”

The Functional Role of the Tachykinin Consensus Region of Urechistachykinin Peptide Family for Its Antimicrobial Activity

“…Depending on the prepro urechistachykinin cDNA sequence, the precursor encodes five more putative sequences (U III-VII) which take part in the endogenous functions of tachykinins. 3) In this study, to investigate the functional role of the conserved sequence of the tachykinin in U II, the structural requirements of U II which harbor the antimicrobial activity were investigated by comparing the activity of the template peptide to the three designed analogue peptides.…”