Chennathukuzhi V M, Lefrancois S, Morales C R, Syed V, Hecht N B
Center for Research on Reproduction and Women's Health and Department of Obstetrics and Gynecology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA.
Mol Reprod Dev. 2001 Apr;58(4):460-9. doi: 10.1002/1098-2795(20010401)58:4<460::AID-MRD15>3.0.CO;2-F.
The single copy mouse Testis Brain RNA-Binding Protein (TB-RBP) gene encodes three mRNAs of 3.0, 1.7, and 1.0 kb which only differ in their 3' UTRs. The 1 kb TB-RBP mRNA predominates in testis, while somatic cells preferentially express the 3.0 kb TB-RBP mRNA. Here we show that the 1 kb mRNA is translated several-fold more efficiently than the 3 kb TB-RBP in rabbit reticulocyte lysates and cells with elevated levels of the 1 kB TB-RBP mRNA express high levels of TB-RBP. To determine if the cleavage stimulatory factor CstF 64 can modulate the alternative splicing of the TB-RBP pre-mRNA and therefore TB-RBP expression, CstF 64 levels and binding to alternative polyadenylation sites were examined. CstF 64 is abundant in the testis and preferentially binds to a distal site in the TB-RBP pre-mRNA that produces the 3 kb TB-RBP. Moreover, upregulation or overexpression of CstF 64 increases the poly(A) site selection for the 1 kb TB-RBP mRNA. We propose that the level of the polyadenylation factor CstF 64 modulates the level of TB-RBP synthesis in male germ cells by an alternative processing of the TB-RBP pre-mRNA.
单拷贝的小鼠睾丸脑RNA结合蛋白（TB-RBP）基因编码三种mRNA，大小分别为3.0、1.7和1.0 kb，它们仅在3'非翻译区有所不同。1 kb的TB-RBP mRNA在睾丸中占主导，而体细胞优先表达3.0 kb的TB-RBP mRNA。我们在此表明，在兔网织红细胞裂解物中，1 kb的mRNA比3 kb的TB-RBP翻译效率高几倍，并且1 kB TB-RBP mRNA水平升高的细胞表达高水平的TB-RBP。为了确定切割刺激因子CstF 64是否能调节TB-RBP前体mRNA的可变剪接从而影响TB-RBP的表达，我们检测了CstF 64的水平及其与可变聚腺苷酸化位点的结合情况。CstF 64在睾丸中含量丰富，且优先结合到TB-RBP前体mRNA中产生3 kb TB-RBP的一个远端位点。此外，CstF 64的上调或过表达会增加1 kb TB-RBP mRNA的聚腺苷酸化位点选择。我们提出，聚腺苷酸化因子CstF 64的水平通过TB-RBP前体mRNA的可变加工来调节雄性生殖细胞中TB-RBP的合成水平。
