牛ASCL2基因生物信息学分析

Bioinformatics Analysis of Bovine ASCL2 Gene

在人与小鼠中，ASCL2基因是一个母源表达的印记基因，在早期胚胎和胎盘发育中起重要作用。牛ASCL2基因的印记状态和印记的分子机理还没有被研究。本研究采用生物信息学方法对牛ASCL2基因分子进化、启动子和CpG岛区域以及蛋白的高级结构进行分析和预测，为进一步揭示该基因生物学功能和其分子调控机理奠定基础。对21种哺乳动物ASCL2基因的mRNA序列进化分析表明：这21种哺乳动物问的遗传距离小于0．536，且牛与猪遗传距离最小，为0．106，与基因进化树分析结果一致。CpG岛在线软件预测显示，在牛中，该基因上游5k序列中有三个CpG岛。启动子在线软件预测和转录因子分析相结合显示，启动子最可能位于该基因5’端上游4725--4775bp处CpG岛区域内，此区域包括大量潜在转录因子结合位点，并在4734bp处存在一个TATA框。蛋白质在线软件分析表明，ASCL2基因编码一种螺旋一环一螺旋形转录因子，有仅一螺旋、B一转角和无规则卷曲3种二级结构。

In human and mice, A SCL2 is a maternally expressed imprinted gene and plays an important role in the early embryonic and placental development. The imprinting status and imprinting molecular mechanism of bovine A SCL2 gene have not been studied. The aims of this study are to analyze and predict the molecular evolution, pro- moter, CpG islands and protein advanced structure of bovine A SCL2 gene using software and on-line tool. The result of genetic distance of 21 mammals species indicated that bovine and pig shared the minimum （0.106）, which accor- dant with the phylogenetic tree. The genetic distance of all the species were blow 0.536. CG content was analyzed with CpG Plot online software, the result indicated that there were three CpG islands in 5＇-flanking region. Using promoter online software combined with transcription factor analysis, the potential promoter of bovine A SCL2 gene was predicted to locate in 4 725-4 775 bp of 5＇-flanking region, which overlaps with the CpG island area. Some transcription factor binding sites were detected in this region and a TATA-box was found in 4 734 bp. Protein soft- ware analysis showed that the A SCL2 gene encodes a helix-loop-helix-shaped transcription factor and its secondary structure is relatively simple including a-helix, β-tum and random coil.