Molecular Cloning and mRNA Profile of Insulin-like Growth Factor Type 1 Receptor in Orange-spotted Grouper,Epinephelus coioides

更新时间:2023-08-14

【摘要】 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 andmaintenance of the malignant phenotype.In this study,we cloned the cDNA from the hypothalamus of theorange-spotted grouper(Epinephelus coioides)using reverse transcription PCR(RT-PCR)and the rapidamplification of cDNA ends(RACE)method.The deduced amino acid sequence showed that the receptorcomprises 1413 amino acid residues.It contains cysteine-rich domains in its α-subunit,and a conservedtransmembrane domain and TK domains in its β-subunit.Comparison of the amino acid sequence withthose of other species showed that the grouper IGF-IR shares 90.2%,89.6%,71.9% and 72% similaritywith the IGF-IR of the Japanese flounder,turbot,zebrafish-a and zebrafish-b,respectively.When comparedwith its mammalian homologue,grouper IGF-IR contains a large insertion at its C-terminus.Phylogeneticanalysis has revealed that the grouper IGF-IR belongs to the b-type IGF-IRs and has a higher similarity withflounder and turbot IGF-IR,and a lower similarity(<70%)with human,mouse and avian IGF-IR.GrouperIGF-IR transcripts were detected in the brain,peripheral tissues,embryos and early development larvae bysemi-quantitative RT-PCR assay.It was observed that IGF-IR mRNA expression was greater in the brainthan in peripheral tissues.The level of IGF-IR mRNA expression was much higher in retina,gonad,skeletalmuscle and gill tissues than in liver,heart and thymus tissues.The expression of IGF-IR can be visualizedas a ubiquitous signal in unfertilized eggs,embryos and early development larvae.The distribution pattern ofIGF-IR mRNA in grouper development suggests that IGF-IR plays an important role in the embryo andearly larval development stages.

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