Wuhan University, Hubei, China.
Mol Cell. 2009 Dec 25;36(6):996-1006. doi: 10.1016/j.molcel.2009.12.003.
Recent transcriptome analysis indicates that > 90% of human genes undergo alternative splicing, underscoring the contribution of differential RNA processing to diverse proteomes in higher eukaryotic cells. The polypyrimidine tract-binding protein PTB is a well-characterized splicing repressor, but PTB knockdown causes both exon inclusion and skipping. Genome-wide mapping of PTB-RNA interactions and construction of a functional RNA map now reveal that dominant PTB binding near a competing constitutive splice site generally induces exon inclusion, whereas prevalent binding close to an alternative site often causes exon skipping. This positional effect was further demonstrated by disrupting or creating a PTB-binding site on minigene constructs and testing their responses to PTB knockdown or overexpression. These findings suggest a mechanism for PTB to modulate splice site competition to produce opposite functional consequences, which may be generally applicable to RNA-binding splicing factors to positively or negatively regulate alternative splicing in mammalian cells.
最近的转录组分析表明，超过 90%的人类基因经历可变剪接，这突显了不同的 RNA 加工对高等真核细胞中多样化蛋白质组的贡献。多嘧啶 tract 结合蛋白 PTB 是一种特征明确的剪接抑制剂，但 PTB 敲低会导致外显子包含和跳过。现在，对 PTB-RNA 相互作用的全基因组作图和功能性 RNA 图谱的构建揭示了，在竞争的组成性剪接位点附近的主要 PTB 结合通常会诱导外显子包含，而在替代位点附近的普遍结合通常会导致外显子跳过。这种位置效应通过在迷你基因构建体上破坏或创建一个 PTB 结合位点，并测试它们对 PTB 敲低或过表达的反应进一步得到证明。这些发现为 PTB 调节剪接位点竞争以产生相反的功能结果提供了一种机制，这可能普遍适用于 RNA 结合剪接因子，以正向或负向调节哺乳动物细胞中的可变剪接。
