[Objective] This study investigated the association between a single nucleotide polymorphism (SNP) in the 5'-regulatory region of CGI-58 gene and meat quality of Qinchuan beef cattle and its effect on promoter activity.[Method] A total of 480 Qinchuan beef cattle at the age of 18 to 24 months were selected,and the intramuscular fat content,eye muscle area and back fat thickness were measured.Blood samples were collected from jugular vein and DNA samples were extracted.The 5'-regulatory region of CGI-58 gene was amplified by PCR,its single nucleotide polymorphism was detected by direct sequencing,and the general linear model (GLM) provided by SAS (version 8.1) was used to correlate the single nucleotide polymorphic site and fleshy traits.The potential transcription factor binding sites and methylation levels of CGI-58 gene were analyzed by MatInspector and cMethPrimer.Double luciferase reporter vectors containing different genotypes of SNP sites were constructed and then transfected them into 3T3L-1 and C2C12 cell lines of mouse and bovine preadipoeytes.The relative activity of luciferase in three cells was determined and statistically analyzed.[Result] A new SNP site was found in the 5'-regulatory region of CGI-58 gene:g.14451079A＞C.Three genotypes were detected at g.14451079A＞C locus including AA,CC and AC.AA genotype had the highest frequency,A allele frequency was greater than C allele frequency,and the promoter activity and eye muscle area of AC genotype were significantly higher than that of other genotypes.The g.14451079A＞C mutation from A to C was produced in the second base A of a predicted transcription factor binding site v-myb in the promoter region of the CGI-58 promoter region,and this mutation led to significant changes in promoter activity.The transcription factor binding site was located on the CpG island of software analysis.[Conclusion] The single nucleotide polymorphism of Qinchuan beef cattle CGI-58 gene promoter region g.14451079A＞C site was significantly associated with eye muscle area and had highly significant effect on promoter activity.%[目的]探究秦川肉牛CGI-58基因5'-调控区中1个新单核苷酸多态(single nucleotide polymorphism,SNP)位点与肉品质的关联性,及其对该基因启动子活性的影响.[方法]选取18～24月龄的480头秦川肉牛为研究对象,测定其肌内脂肪含量、眼肌面积和背膘厚等肉品质性状指标.颈静脉采集试验牛血样,提取DNA样品,PCR扩增CGI-58基因5’-调控区,通过直接测序技术检测其单核苷酸多态性,并使用SAS(version 8.1)软件提供的一般线性模型(GLM)对单核苷酸多态位点与肉质性状进行关联分析.通过MatInspector和cMethPrimer软件分析CGI-58基因潜在的转录因子结合位点及其甲基化水平.构建含有SNP位点不同基因型的双荧光素酶报告载体,并转染小鼠3T3L-1、C2C12细胞系和牛前体脂肪细胞,测定其在3种细胞中的荧光素酶相对活性,并进行统计学分析.[结果]在秦川肉牛CGI-58基因5’-调控区发现1个新的SNP位点:g.14451079A＞C.g.14451079A＞C位点共有3种基因型:AA、CC和AC,其中AA基因型频率最高,A等位基因频率大于C等位基因频率,且AC基因型的启动子活性与眼肌面积显著高于其他基因型.g.14451079A＞C由A到C的突变发生在CGI-58启动子区域中一个预测的转录因子结合位点v-myb的第2个碱基A上,该突变导致启动子活性发生了显著变化,且该转录因子结合位点位于软件分析的CpG岛上.[结论]秦川肉牛CGI-58基因启动子区g.14451079A＞C位点的单核苷酸多态性与眼肌面积存在显著关联,且对该基因启动子活性有极显著影响.
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