中国猪种SLA-DR基因的克隆及序列分析

Molecular Cloning and Characterization of SLA-DR Genes for Three Chinese Swine Strains

为探讨SLA DR基因结构及其在猪 人异种器官移植中的作用 ,本研究采用RT PCR扩增三个中国猪种SLA DRcDNA ,然后克隆入测序载体 ,进行双向测序 ,获得了具有完整阅读框架的三个结构和已有序列不同的新DRB等位基因 ,其长度为80 1个核苷酸 ,除末端终止密码外 ,编码 2 6 6个氨基酸残基 ;三个中国猪种DRA基因和已报告的NIH小型猪DRA基因结构相同 ,其长度均为 75 9个核苷酸 ,除末端终止密码外 ,编码 2 5 2个氨基酸残基。分析还揭示 ,(1)中国猪种SLA DR基因及其推导的氨基酸序列与人相应基因的同源性明显高于小鼠I E基因 ;(2 )中国猪DR分子 (DRα链和β链 )存在和人CD4分子相结合的HLA同源序列 ,但个别关键氨基酸残基发生改变 ,其改变幅度明显低于小鼠I E分子。人 猪MHC显示较高的同源性 ,在分子水平为人体T细胞同时采用直接和间接方式识别猪SLA这一免疫学现象提供了依据。

To elucidate the structures of SLA DR genes of three partially inbred Chinese swine strains(GX, GZ and YN), RT PCR was used to amplify their SLA DRA and DRB cDNA, and the sequences of the amplified DNA were determined Three SLA DRB alleles were thus obtained, each of which came from one strain, and had the same length of 801 nucleotides with an complete open reading frame (ORF) Their sequences, however, were different in comparison with each other or with those of published sequences of SLA DRB genes, suggested that the GX DRB, GZ DRB and YN DRB were new alleles With an ORF of 759 nucleotides, the three SLA DRA alleles GX DRA, GZ DRA, and YN DRA however, were identical in terms of sequences, which were shared by the alleles SLA DRA c and SLA DRA d from NIH minipig Moreover, a phylogenetic analysis of the sequences revealed that both SLA DRA and SLA DRB of the swine strains were more similar to HLA DRA/DRB1*0101 than to H 2 Eα/Eβ The human CD4 binding sites of HLA DR molecule and their counterparts in swine and mouse were further analyzed These data indicated that most of these sites are conserved among the related molecules, in porcine and in human, the substitution patterns in the porcine DR molecules are quite different from those of the mouse H 2 Eα/β chain