Wang Zhong, Lin Haifan
Department of Cell Biology, Duke University Medical School, Durham, NC 27710, USA.
Dev Biol. 2007 Feb 1;302(1):160-8. doi: 10.1016/j.ydbio.2006.09.016. Epub 2006 Sep 15.
The RNA Recognition Motif (RRM) type RNA binding protein Bruno is required for the differentiation of cystoblasts, the committed daughters of germline stem cells in the Drosophila ovary. To understand how Bruno controls cystoblast differentiation, we used a bioinformatics approach to identify potential mRNA targets of Bruno. One such target is the Sex-lethal (Sxl) transcript MS11, which contains four Bruno Response Elements (BREs) in its 3' untranslated region. Electrophoresis mobility shift assays demonstrated that Bruno specifically binds to the BREs of Sxl MS11 mRNA. Tagged transgenic Sxl MS11 cDNA constructs were used to show that Bruno represses the translation of the Sxl MS11 mRNA via the BRE-containing region in the 3'UTR. The lack of either Bruno or the BRE-containing region leads to overexpression of SXL, which in turn causes defects in cystoblast differentiation similar to the Bruno mutant phenotype. Therefore, Sxl MS11 represents a novel target of Bruno-mediated translational repression required for cystoblast differentiation.
RNA识别基序（RRM）型RNA结合蛋白布鲁诺（Bruno）是果蝇卵巢中生殖系干细胞定向分化产生的成囊细胞分化所必需的。为了了解布鲁诺如何控制成囊细胞分化，我们采用生物信息学方法来鉴定布鲁诺潜在的mRNA靶标。其中一个靶标是性致死（Sex-lethal，Sxl）转录本MS11，其3'非翻译区含有四个布鲁诺反应元件（BREs）。电泳迁移率变动分析表明，布鲁诺特异性结合Sxl MS11 mRNA的BREs。带有标签的转基因Sxl MS11 cDNA构建体用于证明布鲁诺通过3'UTR中含BRE的区域抑制Sxl MS11 mRNA的翻译。缺乏布鲁诺或含BRE的区域会导致SXL过表达，进而导致成囊细胞分化缺陷，类似于布鲁诺突变体表型。因此Sxl MS11代表了布鲁诺介导的成囊细胞分化所需的翻译抑制的一个新靶标。
