Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
Nucleic Acids Res. 2018 Feb 28;46(4):2030-2044. doi: 10.1093/nar/gkx1255.
The PolyC binding proteins (PCBPs) impact alternative splicing of a subset of mammalian genes that are enriched in basic cellular functions. Here, we focus our analysis on PCBP-controlled cassette exon-splicing within the cell cycle control regulator cyclin-dependent kinase-2 (CDK2) transcript. We demonstrate that PCBP binding to a C-rich polypyrimidine tract (PPT) preceding exon 5 of the CDK2 transcript enhances cassette exon inclusion. This splice enhancement is U2AF65-independent and predominantly reflects actions of the PCBP1 isoform. Remarkably, PCBPs' control of CDK2 ex5 splicing has evolved subsequent to mammalian divergence via conversion of constitutive exon 5 inclusion in the mouse CDK2 transcript to PCBP-responsive exon 5 alternative splicing in humans. Importantly, exclusion of exon 5 from the hCDK2 transcript dramatically represses the expression of CDK2 protein with a corresponding perturbation in cell cycle kinetics. These data highlight a recently evolved post-transcriptional pathway in primate species with the potential to modulate cell cycle control.
多聚嘧啶结合蛋白（PCBP）影响一组哺乳动物基因的选择性剪接，这些基因富集了基本的细胞功能。在这里，我们将分析重点放在细胞周期调控因子细胞周期蛋白依赖性激酶-2（CDK2）转录本中 PCBP 控制的盒式外显子剪接上。我们证明 PCBP 与 CDK2 转录本外显子 5 前的富含 C 的嘧啶多聚嘧啶区（PPT）结合，增强了盒式外显子的包含。这种剪接增强与 U2AF65 无关，主要反映了 PCBP1 同工型的作用。值得注意的是，PCBP 对 CDK2 ex5 剪接的控制是在哺乳动物分化后通过将小鼠 CDK2 转录本中组成性外显子 5 的包含转换为人类中对 PCBP 有反应的外显子 5 选择性剪接而进化的。重要的是，hCDK2 转录本中外显子 5 的缺失显著抑制了 CDK2 蛋白的表达，并相应地扰乱了细胞周期动力学。这些数据突出了灵长类动物中最近进化的转录后途径，具有调节细胞周期控制的潜力。
