中国大鲵促甲状腺激素受体的克隆及序列分析
The Cloning and Analysis of TSHR Genes in Andrias davidianus
王勤，何青，袁月华，徐海龙，李成磊
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DOI：
作者单位：(四川农业大学生命科学学院，四川雅安625014)
中文关键字：中国大鲵；克隆；甲状腺激素受体；组织分布
英文关键字：Andrias davidianus; cloning; TSHR; tissue distribution
中文摘要：本实验以大鲵脑组织为材料，通过RT-PCR和RACE方法成功获得了中国大鲵Andrias davidianus 促甲状腺激素受体(TSHR) cDNA全长序列。该序列编码585个氨基酸，具有典型的G蛋白偶联受体家族的特点，有4个N-糖基化位点，7个跨膜α螺旋。同源分析显示，大鲵TSHR与热带爪蟾、变色龙、人的TSHR同源性分别为70%、70%和67%。同时大鲵与其它脊椎动物TSHR在结构上存在一些差异，如缺乏前导序列、胞外部分序列缩短、没有富含亮氨酸的重复单位(LRRs)等，大鲵TSHR结构上的这些差异是否与其不同的生理功能相关有待进一步研究。利用邻接法对部分脊椎动物TSHR氨基酸序列构建分子系统树，结果显示有尾目大鲵为两栖动物中较早分化的一支，表明其进化地位较原始。RT-PCR组织分布分析发现，TSHR基因在大鲵的甲状腺外组织也有表达，其中性腺组织表达量最高，这可能暗示TSHR与大鲵的生殖调节有关。
英文摘要：In the present study, we cloned the cDNA sequence of TSHR from the brain tissue of the Chinese giant salamander Andrias davidianus. The cDNA of thyroid-stimulating hormone receptor (TSHR) was 1922 bp in length, including an open reading frame of 1758 bp and coding 585 amino acids, which showed 70%, 67% and 70% similarity to TSHR of Xenopus tropicalis, Homo sapiens and Anolis carolinensis respectively. The A. davidianus TSHR has four consensus sites for N-linked glycosylation and seven transmembrane domains. Compared with other vertebrate TSHR, A. davidianus TSHR had some structural differences, such as lack of guide sequence and leucine rich repeats, relative short extracellular sequence, etc. Whether these differences were involved in different functions of TSHR in A. davidianus still needs further study. In Neighbor-joining (NJ) phylogenetic tree of 36 vertebrate TSHR protein sequences, A. davidianus derived firstly from amphibian, which could reflect its basal evolutionary status within amphibian. The semi-quantitative analysis of tissue-specific expression suggested that the TSHR was also expressed in extra-thyroidal organs, especially in testis which showed a significant high expression level. These suggested that TSHR might be associated with the reproduction regulation of A. davidianus. Our results provided basic data for future studies concerning the function of TSHR in Caudata.