SKIP counteracts p53-mediated apoptosis via selective regulation of p21Cip1 mRNA splicing
SKIP counteracts p53-mediated apoptosis via selective regulation of p21Cip1 mRNA splicing
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DOI：
10.1101/gad.2002611
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发表时间：
2011-04-01
影响因子：
10.5
通讯作者：
Jones, Katherine A.
中科院分区：
文献类型：
--
作者：
Chen, Yupeng;Zhang, Lirong;Jones, Katherine A.
ski相互作用蛋白SKIP/SNW1既是诱导基因的剪接因子，也是转录辅激活因子。我们先前表明转录延伸因子如SKIP在遭受DNA损伤应激的细胞中是必不可少的。然而，我们在这里报道SKIP对于基础和应激诱导的细胞周期阻滞因子p21（Cip1）的表达至关重要。RNAi染色质免疫沉淀（RNAi- chip）和RNA免疫沉淀（RNA- ip）实验表明，SKIP不是胁迫下基因转录延伸所必需的，而是剪接和p21（Cip1）蛋白表达的关键。SKIP与3 '剪接位点识别因子U2AF65相互作用，并将其招募到p21（Cip1）基因和mRNA上。值得注意的是，SKIP并不需要在其他p53诱导的靶标上剪接或装载U2AF65，包括促凋亡基因PUMA。因此，SKIP的缺失诱导p21（Cip1）的快速下调，并使细胞容易经历p53介导的细胞凋亡，这一过程被化疗性DNA损伤剂大大增强。ChIP实验显示SKIP被招募到p21（Cip1）基因启动子上，而不是PUMA基因启动子上，这表明p21（Cip1）基因特异性剪接主要是共转录的。skip相关因子DHX8和Prp19也是胁迫下p21（Cip1）表达的选择性必需因子。总之，这些研究确定了控制癌细胞凋亡的新步骤。
The Ski-interacting protein SKIP/SNW1 functions as both a splicing factor and a transcriptional coactivator for induced genes. We showed previously that transcription elongation factors such as SKIP are dispensable in cells subjected to DNA damage stress. However, we report here that SKIP is critical for both basal and stress-induced expression of the cell cycle arrest factor p21(Cip1). RNAi chromatin immunoprecipitation (RNAi-ChIP) and RNA immunoprecipitation (RNA-IP) experiments indicate that SKIP is not required for transcription elongation of the gene under stress, but instead is critical for splicing and p21(Cip1) protein expression. SKIP interacts with the 3` splice site recognition factor U2AF65 and recruits it to the p21(Cip1) gene and mRNA. Remarkably, SKIP is not required for splicing or loading of U2AF65 at other investigated p53-induced targets, including the proapoptotic gene PUMA. Consequently, depletion of SKIP induces a rapid down-regulation of p21(Cip1) and predisposes cells to undergo p53-mediated apoptosis, which is greatly enhanced by chemotherapeutic DNA damage agents. ChIP experiments reveal that SKIP is recruited to the p21(Cip1), and not PUMA, gene promoters, indicating that p21(Cip1) gene-specific splicing is predominantly cotranscriptional. The SKIP-associated factors DHX8 and Prp19 are also selectively required for p21(Cip1) expression under stress. Together, these studies define a new step that controls cancer cell apoptosis.