Regulation of H-ras splice variant expression by cross talk between the p53 and nonsense-mediated mRNA decay pathways
Regulation of H-ras splice variant expression by cross talk between the p53 and nonsense-mediated mRNA decay pathways
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DOI：
10.1128/mcb.00272-07
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发表时间：
2007-10-01
影响因子：
5.3
通讯作者：
Auboeuf, Didier
中科院分区：
文献类型：
--
作者：
Barbier, Jerome;Dutertre, Martin;Auboeuf, Didier
当细胞暴露在基因毒性应激中时，涉及P53的DNA监控通路被激活，从而允许DNA修复。真核细胞还进化出了一种控制mRNAs质量的机制，称为信使核糖核酸监视。事实上，携带提前翻译终止密码子(PTCs)的突变的mRNAs被无义介导的mRNA衰退(NMD)途径选择性地降解。然而，在特定基因的情况下，例如原癌基因，不会产生PTC从而不会导致mRNA降解的突变可能对细胞有害。在这项研究中，我们证明了H-ras基因在没有突变的情况下会产生一种NMD靶标剪接变异体，该变异体在细胞质中被降解。我们观察到，用基因毒性应激诱导剂喜树碱处理6h，有利于产生经NMD过程在细胞质中降解的H-ras NMD-靶向转录本。我们的数据表明，NMD过程允许消除主要原癌基因H-ras中因喜树碱短期治疗而产生的转录本，而不依赖于突变诱导的PTCs。喜树碱对H-ras基因表达的影响依赖于P53，并参与了SC35剪接因子的部分调控。有趣的是，长期使用喜树碱和P53过表达24小时可导致H-ras NMD靶点在胞浆中积聚，但由于其他NMD靶点不稳定，NMD过程并未完全被抑制。最后，主要的NMD效应器UPF1是喜树碱最佳激活P53所必需的，这与最近的数据表明NMD效应器是基因组稳定所必需的。总而言之，我们确定了调控H-ras剪接变异体表达水平的P53和NMD通路之间的串扰。
When cells are exposed to a genotoxic stress, a DNA surveillance pathway that involves p53 is activated, allowing DNA repair. Eukaryotic cells have also evolved a mechanism called mRNA surveillance that controls the quality of mRNAs. Indeed, mutant mRNAs carrying premature translation termination codons (PTCs) are selectively degraded by the nonsense-mediated mRNA decay (NMD) pathway. However, in the case of particular genes, such as proto-oncogenes, mutations that do not create PTCs and therefore that do not induce mRNA degradation, can be harmful to cells. In this study, we showed that the H-ras gene in the absence of mutations produces an NMD-target splice variant that is degraded in the cytosol. We observed that a treatment with the genotoxic stress inducer camptothecin for 6 It favored the production of the H-ras NMD-target transcript degraded in the cytosol by the NMD process. Our data indicated that the NMD process allowed the elimination of transcripts produced in response to a short-term treatment with camptothecin from the major proto-oncogene H-ras, independently of PTCs induced by mutations. The camptothecin effects on H-ras gene expression were p53 dependent and involved in part modulation of the SC35 splicing factor. Interestingly, a long-term treatment with camptothecin as well as p53 overexpression for 24 h resulted in the accumulation of the H-ras NMD target in the cytosol, although the NMD process was not completely inhibited as other NMD targets are not stabilized. Finally, Upf1, a major NMD effector, was necessary for optimal p53 activation by camptothecin, which is consistent with recent data showing that NMD effectors are required for genome stability. In conclusion, we identified cross talk between the p53 and NMD pathways that regulates the expression levels of H-ras splice variants.