RRC ID 31794
Author Kobayashi Y, Hamamoto A, Hirayama T, Saito Y.
Title Molecular cloning, expression, and signaling pathway of four melanin-concentrating hormone receptors from Xenopus tropicalis.
Journal Gen Comp Endocrinol
Abstract Melanin-concentrating hormone (MCH) mainly regulates feeding in mammals and pigmentation in teleosts. It acts via two G-protein-coupled receptors, MCH receptor 1 (MCHR1) and MCHR2. Although many studies exploring the MCH system in teleosts and mammals have been carried out, studies on other organisms are limited. In this study, we cloned and characterized four MCHR subtypes from the diploid species Xenopus tropicalis (X-MCHRs; X-MCHR1a, R1b, R2a, and R2b). According to a phylogenetic tree of the X-MCHRs, X-MCHR1a and R2a are close to mammalian MCHRs, while X-MCHR1b and R2b are close to teleostean MCHRs. We previously reported that the G-protein coupling capacity of the MCHR subtypes differed between mammals (R1: Gαi/o and Gαq; R2: Gαq) and teleosts (R1: Gαq; R2: Gαi/o and Gαq) in mammalian cell-based assays. By using Ca(2+) mobilization assays with pertussis toxin in CHO dhfr(-) cells, we found that X-MCHR1a promiscuously coupled to both Gαi/o and Gαq, while X-MCHR1b and R2a exclusively coupled to Gαq. However, no Ca(2+) influx was detected in cells transfected with X-MCHR2b. Reverse transcription-PCR showed that the X-MCHR mRNAs were expressed in various tissues. In particular, both X-MCHR1b and R2b were exclusively found in melanophores of the dorsal skin. In skin pigment migration assays, melanophores were weakly aggregated at low concentrations but dispersed at high concentrations of MCH, suggesting possible interactions between X-MCHR1b and R2b for the regulation of body color. These findings demonstrate that X. tropicalis has four characteristic MCHRs and will be useful for elucidating the nature of MCHR evolution among vertebrates.
Volume 212
Pages 114-23
Published 2015-2-1
DOI 10.1016/j.ygcen.2014.03.005
PII S0016-6480(14)00078-1
PMID 24662390
MeSH Amino Acid Sequence Animals Blotting, Western CHO Cells Calcium / metabolism Cloning, Molecular Cricetulus Gene Expression Regulation* Hypothalamic Hormones / genetics* Hypothalamic Hormones / metabolism Melanins / genetics* Melanins / metabolism Melanophores / metabolism Molecular Sequence Data Phylogeny Pituitary Hormones / genetics* Pituitary Hormones / metabolism RNA, Messenger / genetics Real-Time Polymerase Chain Reaction Receptors, Pituitary Hormone / genetics* Receptors, Pituitary Hormone / metabolism Reverse Transcriptase Polymerase Chain Reaction Sequence Homology, Amino Acid Signal Transduction* Skin / metabolism Xenopus / genetics* Xenopus / growth & development
IF 2.428
Times Cited 6
Xenopus tropicalis Nigerian H line