斑点叉尾鮰巨噬细胞移动抑制因子(MIF)基因多态性及表达分析

Polymorphisms and Expression of Macrophage Migration Inhibitory Factor Gene from Channel Catfish,Ictalurus punctatus

巨噬细胞移动抑制因子(MIF)是一类主要由T细胞产生、负责机体在环境协迫和炎症反应中进行免疫应答的细胞因子。根据斑点叉尾鮰MIF基因EST序列,应用RACE技术克隆了MIF 3'UTR和5'UTR序列,利用Genome Walking技术克隆了MIF启动子序列,通过特异PCR克隆MIF内含子序列,并对多个体MIF基因组序列进行多态性分析,利用荧光定量PCR研究MIF的组织分布。结果显示,斑点叉尾鮰MIF基因组序列共3 918 bp,其中编码区348 bp,编码115个氨基酸,5'UTR为70 bp,3'UTR为434 bp,启动子为1 382 bp,共有2个内含子,分别为243 bp和1 441 bp。MIF基因组序列中包含4个重复单元序列和60个多态性位点,其中共有6个SNP位于转录因子结合位点上。斑点叉尾鮰MIF mRNA在肠中表达量最高,肌肉中表达量最低。

Macrophage migration inhibitory factor （ MIF ） was considered as a unique cytokine produced by T-cell and involved in immune response to inflammation and stress. In this study, the genomic sequence of MIF was identified, and the polymorphisms and expression level were studied in channel catfish lctalurus punctatus. The genomic sequence of MIF was identified to be 3 918 bp, consisting of a 70 bp 5＇-untranslated region （ UTR ） , a 160 bp 3＇-UTR, a 348 bp open reading frame （ORF） , two introns as 243 and l 441 bp, and a 1382 bp promoter. Four repetitive sequences were found in promoter and introns. Sixty sites of single nucleotide polymorphisms （ SNPs ） were identified in MIF genomie sequence, among which 6 sites were found to locate in the binding sites for transcription factor. MIF was found to be most abundantly expressed in intestine, and weaker in other tissues. These results could give more information and greater understanding of the degree of MIF genetic variation.