Tài liệu Báo cáo khoa học: A novel tachykinin-related peptide receptor of Octopus vulgaris –

A novel tachykinin-related peptide receptor of Octopus

vulgaris – evolutionary aspects of invertebrate tachykinin

and tachykinin-related peptide

Atsuhiro Kanda, Kyoko Takuwa-Kuroda, Masato Aoyama and Honoo Satake

Suntory Institute for Bioorganic Research, Osaka, Japan

Tachykinins (TKs) are vertebrate multifunctional brain ⁄

gut peptides involved in various central and peripheral

functions, including smooth muscle contraction, vaso￾dilatation, inflammation, and the processing of sensory

information in a neuropeptidergic or endocrine ⁄

paracrine fashion [1–4]. The major mammalian TK

family peptides are Substance P (SP), neurokinin (NK)

A (NKA), NKB, and hemokinin-1 ⁄ endokinins. The

vertebrate TKs share a common motif, FXGLM-NH2,

at their C-termini [1,5]. Three mammalian TK recep￾tors (TKRs), NK1, NK2 and NK3 receptors (NK1R,

NK2R, NK3R), have so far been identified. These

receptors belong to the class I G-protein-coupled

receptor (GPCR) family, and have been shown to trig￾ger the phospholipase C–inositol triphosphate–calcium

signal transduction cascade via coupling to Gq

Keywords

evolution; Octopus vulgaris; oct-TKRPR;

tachykinin-related peptide receptor;

tachykinin

Correspondence

A. Kanda, Suntory Institute for Bioorganic

Research, 1-1-1 Wakayamadai, Shimamoto￾cho, Mishima-gun, Osaka 618-8503, Japan

Fax: +81 75 962 2115

Tel: +81 75 962 3743

E-mail: [email protected]

Database

Nucleotide sequence data are available in

the DDBJ ⁄ EMBL ⁄ GenBank databases under

the accession number AB096700

(Received 16 December 2006, revised 17

February 2007, accepted 28 February 2007)

doi:10.1111/j.1742-4658.2007.05760.x

The tachykinin (TK) and tachykinin-related peptide (TKRP) family repre￾sent one of the largest peptide families in the animal kingdom and exert

their actions via a subfamily of structurally related G-protein-coupled

receptors. In this study, we have identified a novel TKRP receptor from

the Octopus heart, oct-TKRPR. oct-TKRPR includes domains and motifs

typical of G-protein-coupled receptors. Xenopus oocytes that expressed

oct-TKRPR, like TK and TKRP receptors, elicited an induction of mem￾brane chloride currents coupled to the inositol phosphate ⁄ calcium pathway

in response to Octopus TKRPs (oct-TKRP I–VII) with moderate ligand

selectivity. Substance P and Octopus salivary gland-specific TK, oct-TK-I,

completely failed to activate oct-TKRPR, whereas a Substance P analog

containing a C-terminal Arg-NH2 exhibited equipotent activation of

oct-TKRPs. These functional analyses prove that oct-TKRPs, but not

oct-TK-I, serve as endogenous functional ligands through oct-TKRPR,

although both of the family peptides were identified in a single species, and

the importance of C-terminal Arg-NH2 in the specific recognition of

TKRPs by TKRPR is conserved through evolutionary lineages of Octopus.

Southern blotting of RT-PCR products revealed that the oct-TKRPR

mRNA was widely distributed in the central and peripheral nervous

systems plus several peripheral tissues. These results suggest multiple

physiologic functions of oct-TKRPs as neuropeptides both in the Octopus

central nervous system and in peripheral tissues. This is the first report

on functional discrimination between invertebrate TKRPs and salivary

gland-specific TKs.

Abbreviations

GPCR, G-protein coupled receptor; inv-TK, invertebrate tachykinin; NK, neurokinin; NKR, neurokinin receptor; oct-TK, Octopus tachykinin;

oct-TKRP, Octopus tachykinin-related peptide; oct-TKRPR, Octopus tachykinin-related peptide receptor; SP, Substance P; TK, tachykinin;

TKR, tachykinin receptor; TKRP, tachykinin-related peptide; TKRPR, tachykinin-related peptide receptor; TM, transmembrane domain.

FEBS Journal 274 (2007) 2229–2239 ª 2007 The Authors Journal compilation ª 2007 FEBS 2229