Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.
Cell. 2012 Aug 17;150(4):710-24. doi: 10.1016/j.cell.2012.06.041.
The muscleblind-like (Mbnl) family of RNA-binding proteins plays important roles in muscle and eye development and in myotonic dystrophy (DM), in which expanded CUG or CCUG repeats functionally deplete Mbnl proteins. We identified transcriptome-wide functional and biophysical targets of Mbnl proteins in brain, heart, muscle, and myoblasts by using RNA-seq and CLIP-seq approaches. This analysis identified several hundred splicing events whose regulation depended on Mbnl function in a pattern indicating functional interchangeability between Mbnl1 and Mbnl2. A nucleotide resolution RNA map associated repression or activation of exon splicing with Mbnl binding near either 3' splice site or near the downstream 5' splice site, respectively. Transcriptomic analysis of subcellular compartments uncovered a global role for Mbnls in regulating localization of mRNAs in both mouse and Drosophila cells, and Mbnl-dependent translation and protein secretion were observed for a subset of mRNAs with Mbnl-dependent localization. These findings hold several new implications for DM pathogenesis.
肌萎缩侧索硬化症相关蛋白（Mbnl）家族的 RNA 结合蛋白在肌肉和眼睛发育以及肌强直性营养不良（DM）中发挥重要作用，其中扩展的 CUG 或 CCUG 重复序列在功能上耗尽了 Mbnl 蛋白。我们通过 RNA-seq 和 CLIP-seq 方法，在大脑、心脏、肌肉和肌母细胞中鉴定了 Mbnl 蛋白的转录组范围的功能和生物物理靶点。该分析确定了数百个剪接事件，其调节取决于 Mbnl 功能，表明 Mbnl1 和 Mbnl2 之间具有功能可互换性。核苷酸分辨率 RNA 图谱将外显子剪接的抑制或激活与 Mbnl 在 3' 剪接位点附近或下游 5' 剪接位点附近的结合分别相关联。亚细胞区室的转录组分析揭示了 Mbnls 在调节小鼠和果蝇细胞中 mRNA 定位方面的全局作用，并且观察到具有 Mbnl 依赖性定位的一组 mRNA 存在 Mbnl 依赖性翻译和蛋白质分泌。这些发现对 DM 的发病机制具有若干新的意义。
