ZFIN ID: ZDB-PUB-100621-41
Two functional growth hormone secretagogue receptor (ghrelin receptor) type 1a and 2a in goldfish, Carassius auratus
Kaiya, H., Miura, T., Matsuda, K., Miyazato, M., and Kangawa, K.
Date: 2010
Source: Molecular and Cellular Endocrinology   327(1-2): 25-39 (Journal)
Registered Authors: Matsuda, Kouhei
Keywords: cDNA cloning, Gene, Ghrelin, Ghrelin receptor, Goldfish, GHS-R1a, GHS-R2a, Liver, Vagal lobe
MeSH Terms:
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Biological Assay
  • Calcium/metabolism
  • Cell Line
  • DNA, Complementary/genetics
  • Fasting
  • Gene Expression Profiling
  • Gene Expression Regulation/drug effects
  • Ghrelin/pharmacology
  • Goldfish/genetics*
  • Humans
  • Intracellular Space/drug effects
  • Intracellular Space/metabolism
  • Molecular Sequence Data
  • Phylogeny
  • RNA, Messenger/genetics
  • RNA, Messenger/metabolism
  • Receptors, Ghrelin/chemistry
  • Receptors, Ghrelin/genetics*
  • Receptors, Ghrelin/metabolism
  • Sequence Homology, Amino Acid
PubMed: 20558240 Full text @ Mol. Cell. Endocrinol.
Here we report the identification and characterization of ghrelin (GRLN) receptors in goldfish Carassius auratus. We identified four distinct mRNAs generated from four different genes. Those were roughly divided into two types, based on the number of amino acids and amino acid sequence similarity; one composed of 360 amino acids, which is similar to zebrafish GHS-R1a (showing 94-96% identity) and the other encodes a 366- or 367-amino acid protein, which demonstrated 95% identity to zebrafish GHS-R2a. We therefore designated these proteins as goldfish GHS-R1a type 1 (1a-1) and 1a-2 and GHS-R2a type 1 (2a-1) and 2a-2. GHS-R1a and 2a proteins share 74% sequence identity with each other. In functional analyses, three of these four receptors (except 2a-2 receptor), were activated by goldfish GRLN or GHS. The GRLN activity was inhibited by [D-Lys(3)] GHRP-6 but not by des-acyl goldfish GRLN. Expression levels of GHS-R1a mRNA were 2 to 50-folds higher than those of GHS-R2a, and GHS-R2a-2 mRNA expression was 1/25 of GHS-R2a-1. GHS-R1a-1 and 1a-2 mRNAs were mainly detected in the central nervous system (CNS), pituitary, liver, intestine and testis, whereas GHS-R2a-1 and 2a-2 mRNAs were predominantly expressed in the CNS, body kidney, ovary and testis. A seven-days fasting led to a decrease in GHS-R1a-1 mRNA expression in the vagal lobe, but stimulated GHS-R1a-2 mRNA in the liver, although no change was observed in GHS-R2a mRNAs. These results indicate that goldfish has four GHS-Ra that is divided into two types, 1a and 2a; and each receptor expression is separately regulated with GHS-R1a acts on energy metabolism.