牙鲆(Paralichthys olivaceus)Activin基因两种β亚基的启动子克隆及生物信息学分析

Bioinformatic Characterization of Promoters of Two Activin-β Subunit Genes in Paralichthys olivaceus

以牙鲆为研究对象,利用染色体步移(Genome walking)获得了Activin两个β亚基基因的上游部分启动子序列,并对其进行了转录调控元件的生物信息学预测分析。获得了ActivinβA和βB两个亚基的启动子部分序列,长度分别约为2.7 kb和2.4 kb;在预测的ActivinβB转录起始位点(+1位)的上游31 bp处有1个典型的TATA box,而在ActivinβA中未发现TATA box的存在。两个基因的启动子上发现了多个转录因子Sp1、Oct-1、C/EBP、CREB、GATA-1、HNF-3、HNF-1、USF等结合位点,还发现了与内分泌相关的Pit-1、ER、PR、GR、RAR、RXR等结合位点,但肌性转录因子Myo D、myogenin和雄性的性别决定基因SRY结合位点仅在ActivinβA启动子中发现。生物信息学分析显示,牙鲆ActivinβA和βB表达受到多种潜在因子的调控,二者在调控上有所差异。

Activin is a member of the transforming growth factor-β （TGF-β） family and regulates sex hormones. It was originally discovered in pig ovarian follicular fluid. Activin contains two β subunits and plays a vital role in the hypothalamus-pituitary-gonad axis （HPG）. It regulates the secretion of pituitary gonadotropin, the production of steroid hormones and the maturation of oocyte in ovary. Paralichthys olivaceus is a type of important commercial fish species that has advantageous traits in aquaculture such as the fast growth rate. Better understanding of its reproduction mechanism is essential for the guidance of the breeding of P. olivaceus. In this study, we analyzed the expression and regulation of Activin gene related to the reproductive endocrinology of P. olivaceus. Our data should provide important information for future studies on biological functions of Activin and for the practice in the culture of P. olivaceus. We used the genome walking method to obtain the partial sequence of promoters located in the upstream of Activin βA and βB genes of P. olivaceus, and predicted the binding sites of transcriptional regulation elements using the bioinformatical method. The promoters of these two genes were 2.7 kb and 2.4 kb in length respectively. The results showed that the TATA box of Activin βB was located at 31 bp in the upstream region of the transcription initiation site, however this structure was not found in Activin βA. We found in the two promoters a number of binding sites of the transcription factors including Sp1, Oct-1, C/EBP, CREB, GATA-1, c-Jun, HNF-3, HNF-1, and USF. Moreover, we also found multiple transcription binding sites of endocrine-related factors such as Pit-1, ER, PR, GR, RAR, and RXR. However, the binding sites of MyoD, myogenin and SRY were only found in Activin βA. In conclusion, the bioinformatical analysis suggested that the basic and hormone-inducing expression of both Activin βA and βB was regulated by a variety of factors; however, the mechanisms of the regulation were different between the two genes.