合作小型猪T细胞受体α链的基因结构及其多样性

Genetic structure and diversity of T cell receptor alpha chain genes in Hezuo minipig

目的探讨猪TCR基因分子结构的复杂性及其与人类的相似性。方法以公开的猪TCRα链基因为参考序列设计两对特异性引物,用RT-PCR法从合作小型猪外周血、淋巴结和脾脏的淋巴细胞中克隆了93个猪TCRα基因（简称STA）。结果测序分析表明,克隆的猪TCRα链的基因均含有可变的信号肽区和V区、高变的J区和恒定的C区的基因片段,但基因间的核苷酸序列组成都不完全相同,且具有十分复杂的多态性和多样性,基因间的同源性在68.4%-98.7%,这与TCRα链的基本基因结构特征相一致。依据TCRα基因的同源性对其分子结构、遗传演化关系和归类分析发现,在其信号肽区、FR1区和CDR1区、FR2区和CDR2区以及FR3区和CDR3区都存在一些变异集中点和变异热点区。用IMGT/V-QUEST分析方法可将合作小型猪TCRαV区（STAV）、J区（STAJ）基因片段与人类的进行比较分析,发现合作小型猪TCRα与人类的遗传演化关系较近,每个序列都能找到与人类对应的TRAV、TRAJ基因片段,甚至V区的相似性可达92%以上。结论近交培育的合作小型猪在正常状态具有应对外界复杂微生物等环境的TCR遗传多样性分子基础,且适合作为人类免疫学及疾病研究的动物模型。

Objective To analyze the complexity of molecular structure in porcine T cell receptor gene and its similarity compared to humans.Method Based on the gene of porcine T cell receptor alpha chain （ TCRα） from the Gen-Bank database, 93 swine T cell receptor alpha chain genes （ STA） were cloned by reverse transcription-polymerase chain reaction （RT-PCR） from porcine peripheral blood lymphocytes, lymph nodes and spleen.Result Sequence analysis showed that STA genes all contain a domain of variable signal peptide and V, hypervariable J and conservative C.However, nucleotide sequence of STA was not completely identical with only 68.4%to 98.7%homology among genes, and had extremely sophisticated polymorphism and diversity.This was accord with the genetic structure of TCRαchain.Molecular structure, genetic evolution and classification of these genes were carried out according to the homology of TCRαgene, which all have several sites and zones of mutation on the domain of signal peptide, FR1 and CDR1, FR2 and CDR2, FR3 and CDR3.Analysis of similarity and classification of TCRαV domain（STAV）and J domain （STAJ） of Hezuo minipig u-sing IMGT/V-QUEST tools compared with those of humans found the genetic evolution relationship that was closer, and each of TRAV and TRAJ also found to have a corresponding fragment of humans, ever in 92% of similarity of TRAV between swine and humans.Conclusion Our results indicate that inbred Hezuo minipig possesses genetic diversity against complicated environment of microbes in healthy status, and Hezuo minipig is suitable as an animal model for research on human immunology and diseases.