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ISSN
1672-9145
Acta Biochim Biophys Sin
2005, 37(5): 327–334
CN 31-1940/Q
Molecular Cloning and mRNA Profile of Insulin-like Growth Factor
Type 1 Receptor in Orange-spotted Grouper, Epinephelus coioides
Yue-Mei KUANG#, Wen-Sheng LI#, and Hao-Ran LIN*
Institute of Aquatic Economic Animals and Guangdong Provincial Key
Laboratory for Aquatic Economic Animals,
Zhongshan University, Guangzhou 510275, China
Abstract The insulin-like growth factor type 1 receptor (IGF-IR) belongs to the
tyrosine kinase (TK) receptor family. Besides being mitogenic, IGF-IR plays a
crucial role in cell survival, transformation and maintenance of the malignant
phenotype. In this study, we cloned the cDNA from the hypothalamus of the
orange-spotted grouper (Epinephelus coioides) using reverse
transcription PCR (RT-PCR) and the rapid amplification of cDNA ends (RACE)
method. The deduced amino acid sequence showed that the receptor comprises 1413
amino acid residues. It
contains cysteine-rich domains in its a-subunit, and a
conserved transmembrane domain and TK domains in its b-subunit.
Comparison of the amino acid sequence with those of
other species showed that the grouper IGF-IR shares 90.2%, 89.6%, 71.9% and 72%
similarity with the IGF-IR of the Japanese flounder, turbot, zebrafish-a and
zebrafish-b, respectively. When compared with its mammalian homologue, grouper
IGF-IR contains a large insertion at its C-terminus. Phylogenetic analysis has
revealed that the grouper IGF-IR belongs to the b-type IGF-IRs and has a higher
similarity with flounder and turbot IGF-IR, and a lower similarity (<70%)
with human, mouse and avian IGF-IR. Grouper IGF-IR transcripts were detected in
the brain, peripheral tissues, embryos and early development larvae by
semi-quantitative RT-PCR assay. It was observed that IGF-IR mRNA expression was
greater in the brain than in peripheral tissues. The level of IGF-IR mRNA
expression was much higher in retina, gonad, skeletal muscle and gill tissues
than in liver, heart and thymus tissues. The expression of IGF-IR can be
visualized as a ubiquitous signal in unfertilized eggs, embryos and early
development larvae. The distribution pattern of IGF-IR mRNA in grouper
development suggests that IGF-IR plays an important role in the embryo and
early larval development stages.
Key words orange-spotted grouper (Epinephelus
coioides); insulin-like growth factor type 1 receptor; cDNA cloning; mRNA
expression
—————–
Received: January 6, 2005 Accepted: March 7, 2005
This work was supported by the grants from the National High
Technology Research and Development Program of China (No. 2003AA603410, No.
2003AA603011), the Major State Basic Research Development Program of China
(2004CB117402) and the Natural Science Foundation of Guangdong Province (No.
20023002)
#These two authors contributed equally
to this work
*Correspondent
author: Tel, 86-20-84113791; Fax, 86-20-84113717; E-mail, [email protected]