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This Article Accepted manuscript (PDF) All Versions of this Article: JOE-08-0325v1 199/2/253    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Chen, T. Articles by Lin, H. Search for Related Content PubMed PubMed Citation Articles by Chen, T. Articles by Lin, H.

T Chen, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China
Z Tang, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China
A Yan, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China
W Li, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China
H Lin, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China

Correspondence: Wensheng Li, Email: lsslws{at}mail.sysu.edu.cn

Abstract

Growth hormone secretagogue receptor (GHS-R) is the receptor of ghrelin, a circulating GH-releasing and appetite-inducing hormone. In this paper, two GHS-R cDNAs, namely for gpGHS-R1a and gpGHS-R1b, were identified and characterized in a teleost, the orange-spotted grouper (Epinephelus coioides). The gpGHS-R1a is 1512bp in length with an open reading frame that encodes a protein of 383 amino acids with seven transmembrane domains, while the 1703bp gpGHS-R1b contains an open reading frame encoding for 303 amino acids with five transmembrane domains. Comparison between cDNA and gene sequences showed that the two transcripts are two alternative splicing forms of a single gpGHS-R gene. Tissue distribution and ontogeny of two gpGHS-R mRNAs were examined by RT-PCR. The gpGHS-R1a is mainly expressed in brain and pituitary gland, as compared with a more widespread expression of gpGHS-R1b. During embryonic and larval development, the gpGHS-R1b mRNA appears before the gpGHS-R1a mRNA. Furthermore, quantitative real-time PCR performed on brain showed that both transcripts have the highest expression level in the pituitary gland. The expression level of gpGHS-R1a was generally higher than that of gpGHS-R1b. GHS-R expressing cells were also detected widely in grouper brain by in-situ hybridization, with a broader distribution than previous reports in mammals. Finally, an in-vitro study showed that expression of both gpGHS-R transcripts in pituitary and hypothalamus is down-regulated by GH and ghrelin but not by des-acyl ghrelin, and this suggests that feedback-regulation of GHS-R also exists in teleostean fishes.