棘腹蛙生长激素/类胰岛素样生长因子轴关键基因的克隆与序列特征分析

摘要

Growth hormone (GH)/insulin-like growth factors (IGFs) axis was composed of GH system and IGFs system, which can promote cell proliferation, regulate growth and development, regulate physiological metabolism, as well as played an important role in the regulation of growth and development.In order to clear the functional structure and evolution characteristics of GH/IGFs axis from Paa boulengeri and to provide the theoretical basis for regulation study of growth and development for Paa boulengeri, the GH, insulin-like growth factor-Ⅰ (IGF-Ⅰ) and insulin-like growth factor-Ⅱ (IGF-Ⅱ) from Paa boulengeri were cloned and the sequence characteristics of them were analyzed.The results showed as follows: 1) multiple sequence alignment with amphibian model animals revealed that GH, IGF-Ⅰ and IGF-Ⅱ displayed respective genetic polymorphisms within conserved functional domains, and the N-terminal domain of IGF-Ⅱ showed a abbreviated evolution trend.2) The phylogenic clustering analysis found that IGFs from Paa boulengeri and amphibians were classified to one cluster, and they had a near relationship with bony fish, which indicated IGF-Ⅰ and IGF-Ⅱ were comparatively ancient genes.IGFs from Paa boulengeri had a near relationship with aquatic animals such as frogs and fishes, which implied GH had a trend of convergent evolution.3) To further define the specific functional sites of above genes, the protein structure of them were analyzed by Swiss-model server software, and some potential functional differentiation sites were found including THR52, LEU53, PHE72, PHE73 and SER74 from IGF-Ⅰ, TYR81, LYS82 and LYS83 from IGF-Ⅱ, and PHE208 from GH.The results indicate that the major genes of GH/IGFs axis from Paa boulengeri are relatively conserved, but their exist some potential functional differentiation sites compared with known model species, which can be as molecular targets for the functional study and genetic characteristics analysis of GH/IGFs axis from Paa boulengeri in future.%机体的生长激素(GH)/类胰岛素样生长因子(IGFs)轴由GH系统和IGFs系统构成,可促进细胞增殖、调节生长发育、调控生理代谢,在机体生长发育调控方面有着重要作用.为明确棘腹蛙GH/IGFs轴的功能结构和进化特征,为棘腹蛙生长发育调控方面的研究提供理论依据,本试验对棘腹蛙GH、类胰岛素生长因子-Ⅰ(IGF-Ⅰ)和类胰岛素生长因子-Ⅱ(IGF-Ⅱ)进行克隆并对其序列特征进行分析.结果显示:1)与两栖类模式动物的多重序列比对发现,棘腹蛙GH、IGF-Ⅰ和IGF-Ⅱ的功能结构域严格保守,具有一定的遗传多态性;IGF-Ⅱ的N端呈简缩进化趋势.2)遗传进化聚类分析发现,棘腹蛙IGFs与两栖动物聚为一支,并与硬骨鱼相对近缘,说明IGF-Ⅰ和IGF-Ⅱ进化地位相对原始;棘腹蛙GH则与蛙类、鱼类等水生动物相对近缘,暗示该基因具有趋同进化趋势.3)为进一步明确上述基因的特异性功能位点,利用Swiss-model server软件解析其蛋白质结构,最终确定IGF-Ⅰ的THR52、LEU53、PHE72、PHE73、SER74为潜在的功能分化位点,IGF-Ⅱ的TYR81、LYS82、LYS83为潜在的功能分化位点,GH的PHE208为潜在的功能分化位点.由此可知,棘腹蛙GH/IGFs轴的主要基因相对保守,但与已知模式物种相比,存在潜在的功能分化位点,可作为后期棘腹蛙GH/IGF轴功能研究和遗传进化特征分析的分子靶标.