贵州矮马(Equus caballus)生长激素受体基因5个单核苷酸位点的多态性研究

Polymorphism of Five SNPs in Exon 10 of Growth Hormone Receptor Gene in Guizhou Pony(Equus caballus)

旨在探究贵州矮马生长慢的根本原因,本研究采用PCR和基因克隆技术测定贵州矮马生长激素受体基因(GHR)外显子10的核苷酸序列;以伊犁马为对照,通过AS-PCR和SSCP方法研究贵州矮马群体中SNP位点的分布频率,应用群体遗传学和生物信息学方法分析基因型与体尺指标间的相关性。结果,从贵州矮马GHR外显子10中得到10个单倍型,包括10个SNPs位点,其中的5个引起氨基酸改变。与伊犁马相比,贵州矮马GHR基因1028位点的A等位基因占优势,对应较低的尻高和较粗的管围;1471位点的E等位基因在贵州矮马群体中分布较多,与胸围率较高相关;1697和1732两个位点的杂合型存在于最矮的雄性矮马(6岁)GHR基因中。1028位点引起的V343A位于UbE结构域中,1471、1697和1732位点引起的S491G、Y566C和R578G改变与GHR蛋白的磷酸化有关。这4个位点可能影响GHR的内化作用或通过磷酸化途径影响细胞内的信号传导效率。研究结果提示,贵州矮马GHR基因外显子10中的多态性变化可能影响贵州矮马的生长发育。

To explore the reason for the slow growth of Guizhou pony,sequences of exon 10 in GHRgene were cloned from the genome of Guizhou pony by polymerase chain reaction(PCR)and gene cloning methods.Distribution of 5single nucleotide polymorphism(SNP)sites was determined by allele-specific PCR(AS-PCR)and single-strand conformation polymorphism(SSCP)methods.Taking Ili horse as control,the relationship between the genotypes of GHRand body sizes of Guizhou pony and Ili horse was calculated based on population genetics and bioinformatics algorithms.The results showed that a total of 10 haplotypes of exon 10 of GHR gene were sequenced from Guizhou pony,in which contained 10 SNP sites.Among them,5sites,1028,1267,1471,1697 and 1732,changed the amino acid residues of GHR.Frequencies of 3sites,1028,1267 and 1471,were tested by AS-PCR method.Compared with Ili horse,allele A at site 1028 was dom-inant and related with the lower rump height and higher cannon circumference in Guizhou pony.The percentage of allele E at 1471 site in Guizhou pony was higher than that in Ili horse and related to higher chest girth ratio of pony.Heterozygous genotypes of 1697 and 1732sites were detected from the shortest male pony with 106 cm in height,6years old.The V343 Achange resulted from 1028 site located in the ubiquitin-dependent endocytosis(UbE)motif and might affect the GHR internalization and degradation.Changes at S491 G,Y566Cand R578 Gsites resulted from SNP sites of 1471,1697 and 1732,might directly or indirectly impact the phosphorylation of GHR and influence the activation of signal transduction pathways.It suggested that the polymorphisms in exon 10 of GHRgene might have an effect on the growth and development of Guizhou pony.