小鼠BTB/锌指结构新基因Bsg6的克隆及表达谱分析

Cloning and Expression Analysis of a Novel Mouse Gene BTB/Zinc Finger Gene Bsg6

Bsg6(brain specific gene 6)是用消减差异筛选的方法克隆的小鼠头部特异表达新基因.Bsg6基因cDNA长3 871 bp,编码一个670个氨基酸残基的蛋白,GenBank登录号AY635051,位于小鼠第4号染色体,由2个外显子构成.Bsg6蛋白含有一个N端BTB(Broad-complex,Tramtrack,andBric-a-brac)结构域和两个C端C2H2型锌指结构域.小鼠Bsg6蛋白与其在人类和鸡中同源蛋白的同源性分别为86.2%和79.1%.Bsg6在小鼠胚胎中的表达具有一定动态性,在E8.5的小鼠胚胎中,Bsg6主要在前脑和神经管表达.在E9.5的小鼠胚胎中,Bsg6的表达明显增强并主要集中在前脑的端脑部.Bsg6在E10.5小鼠胚胎端脑的表达出现了下降,但是在中脑和后脑的表达增加,此外,Bsg6 mRNA的表达还出现在肢芽和尾部.在HH10期的鸡胚中,Bsg6主要在头部和神经管前端表达.Northern杂交结果显示,Bsg6在很多小鼠成体组织中没有表达,但是在破骨细胞瘤中高表达.Bsg6的表达谱提示,Bsg6可能是在器官形成期对脑的发育起到重要作用的转录因子,而且其表达受到严格的调控,此外Bsg6还可能与肿瘤的发生有关.

The subtractive differential screening was used to clone a novel mouse gene Bsg6 （brain specific gene 6） expressed specifically in E9.5 mouse embryo brain. As evaluated by DNA sequencing and bioinformatic analysis, the Bsg6 cDNA is 3 871 bp in length encoding a 670-amino-acid protein, the Genebank accession number is AY635051 and the Bsg6 gene is located on mouse chromosome 4 with 2 exons. Bsg6 protein contains a BTB（Broad-complex, Tramtrack, and Bric-a-brac） motif on the N terminus and two consecutive C2 H2 zinc finger motifs on the C terminus. Mouse Bsg6 protein shows high similarity with human and chicken homology protein with identity of 86.2% and 79.1% respectively. Whole-mount in situ hybridization showed that mRNA level of Bsg6 in mouse embryos was vary in different regions of brain. Expression was found in brain and nerve tube of E8.5 mouse embryo. By E9.5, the transcripts of Bsg6 increased significantly and was found predominantly in forebrain. By E10.5, the expression of Bsg6 decreased in forebrain, while increased in midbrain and hindbrain, expression was also found in limb and tail. Bsg6 expression was also found in brain and anterior of nerve tube of HH10 chicken embryo. No Bsg6 mRNA were found in adult mouse tissues, while Bsg6 was expressed in mouse osteoclastoma cell line. The expression patterns of Bsg6 gene suggest that Bsg6 may play an important role and be under strict control in the developing brain in the organogenesis stage, Bsg6 might also play a role in the tumor genesis.