Salmon growth hormone receptor: Molecular cloning, ligand specificity, and response to fasting

Haruhisa Fukada, Yuichi Ozaki, Andrew L. Pierce, Shinji Adachi, Kohei Yamauchi, Akihiko Hara, Penny Swanson, Walton W. Dickhoff

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Abstract

To better understand the role of growth hormone in regulating fish growth, the cDNA of growth hormone receptor (GHR) was cloned from the liver of masu salmon (Oncorhynchus masou) and characterized. The masu salmon GHR (msGHR) sequence revealed common features of a GHR, including a (Y/F)GEFS motif in the extracellular domain, a single transmembrane region, and Box 1 and Box 2 in the intracellular domain. However, the amino acid sequence identity was low (≤49%) compared to GHRs of other vertebrates including seven teleosts, and the putative msGHR protein lacked one pair of cysteine residues in the extracellular domain. To verify the identity of the msGHR, the recombinant protein of the extracellular domain was expressed with a histidine tag protein (His-msGHR-ECD), refolded and purified for analysis of its ligand specificity. In competition experiments, the specific binding between His-msGHR-ECD and radioiodine-labeled salmon GH was displaced completely by only salmon GH, and not by salmon prolactin or somatolactin. A real-time RT-PCR assay was used to measure salmon GHR mRNA in the liver of fed and fasted coho salmon (Oncorhynchus kisutch). The levels of hepatic GHR mRNA were lower in fasted fish compared to fed fish after 3 weeks, suggesting that GHR gene expression is reduced following a long-term fast. These results confirm the identity of the salmon GHR based on ligand specificity and response to fasting.

Original languageEnglish
Pages (from-to)61-71
Number of pages11
JournalGeneral and Comparative Endocrinology
Volume139
Issue number1
DOIs
Publication statusPublished - 2004 Oct

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Keywords

  • Binding assay
  • Cloning
  • Growth hormone
  • Growth hormone receptor
  • Insulin-like growth factor-I
  • Salmon

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Endocrinology

Cite this

Fukada, H., Ozaki, Y., Pierce, A. L., Adachi, S., Yamauchi, K., Hara, A., Swanson, P., & Dickhoff, W. W. (2004). Salmon growth hormone receptor: Molecular cloning, ligand specificity, and response to fasting. General and Comparative Endocrinology, 139(1), 61-71. https://doi.org/10.1016/j.ygcen.2004.07.001