牛Fas基因的组织表达分析及其功能预测

Expression Distribution and Function Prediction of Cattle Fas Gene

采用RT-PCR技术从中国西门塔尔牛睾丸组织总RNA中反转录FascDNA,将其克隆于pMD19-Tvector后进行测序分析,并对其表达的蛋白结构功能进行预测、分析。结果表明:牛的FascDNA序列为1109bp,编码323个氨基酸残基,在氨基酸序列上与羊、猪、人、小鼠的相似性分别为90.5%、65.3%、56.7%和48.6%。Fas蛋白的胞外区有2个糖基化位点和3个富含半胱氨酸残基的结构亚域,对Fas蛋白的定位及凋亡信号识别有重要作用。牛与羊、猪、人、小鼠Fas的死亡结构域(Death domain,DD)氨基酸序列的相似性分别为94.3%、68.5%、59.6%和70.8%,体现了该结构在各物种间较强的保守性及接受凋亡信号诱导靶细胞凋亡的重要性。组织表达谱发现,Fas不仅表达于牛的淋巴、脾等淋巴系统,而且高表达于牛生殖系统的睾丸中,这对于进一步阐明Fas在公牛精子发生过程中的调控作用奠定基础。

The Fas cDNA gene was amplified from the RNA of simmental cattle testis by polymerase chain reaction （PCR）, the PCR products were cloned into PMD19-T vector and sequenced. The results showed that bovine Fas cDNA consisted of 1 109 bp and encoded 323 amino acid residues.The identities of the deduced amino acid sequence of the cattle Fas to sheep, pig, human and mouse were 90.5%,65.3%,56.7% and 48.6%, respectively. There were two N-linked glyeosylation sites and three cysteine-rich domains （CRD）in the extracellular region of Fas protein, they were important for localization and signal recognition of Fas protein. The identities of the cattleJdeath domain （DD） to sheep, pig, human and mouse were 94.3%,68.5%,59.6% and 70.8%, respectively. The intracellular portion of Fas containing death domain was high homology among species. RT-PCR was conducted for 10 tissues, and expression of cattle Fas mRNA was detected not only in the lymph and spleen but in bovine reproductive system of testis, which revealed Fas played an important role in bovine spermatogenesis, follicular development and pregnancy maintenance.