Department of Human Genetics, Instituto Nacional de Saúde Doutor Ricardo Jorge, Lisboa, Portugal; University of Lisboa, Faculty of Sciences, BioISI - Biosystems and Integrative Sciences Institute, Lisboa, Portugal.
Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal.
Biochem Biophys Res Commun. 2019 Oct 22;518(4):664-671. doi: 10.1016/j.bbrc.2019.08.105. Epub 2019 Aug 26.
The nonsense-mediated decay (NMD) pathway selectively degrades mRNAs carrying a premature translation-termination codon but also regulates the abundance of a large number of physiological mRNAs that encode full-length proteins. In human cells, NMD-targeted mRNAs are degraded by endonucleolytic cleavage and exonucleolytic degradation from both 5-' and 3'-ends. This is done by a process not yet completely understood that recruits decapping and 5'-to-3' exonuclease activities, as well as deadenylating and 3'-to-5' exonuclease exosome activities. In yeast, DIS3/Rrp44 protein is the catalytic subunit of the exosome, but in humans, there are three known paralogues of this enzyme: DIS3, DIS3L1, and DIS3L2. However, little is known about their role in NMD. Here, we show that some NMD-targets are DIS3L2 substrates in human cells. In addition, we observed that DIS3L2 acts over full-length transcripts, through a process that also involves UPF1. Moreover, DIS3L2-mediated decay is dependent on the activity of the terminal uridylyl transferases Zcchc6/11 (TUT7/4). Together, our findings establish a role for DIS3L2 and uridylation in NMD.
无意义介导的衰变 (NMD) 途径选择性降解携带过早翻译终止密码子的 mRNA，但也调节大量编码全长蛋白质的生理 mRNA 的丰度。在人类细胞中，NMD 靶向的 mRNA 通过内切核酸酶切割和 5' 和 3' 末端的外切核酸酶降解进行降解。这是通过一个尚未完全理解的过程完成的，该过程招募脱帽和 5' 到 3' 外切核酸酶活性，以及去腺苷酸化和 3' 到 5' 外切酶 exosome 活性。在酵母中，DIS3/Rrp44 蛋白是 exosome 的催化亚基，但在人类中，这种酶有三个已知的同源物：DIS3、DIS3L1 和 DIS3L2。然而，人们对它们在 NMD 中的作用知之甚少。在这里，我们表明一些 NMD 靶向物是人类细胞中 DIS3L2 的底物。此外，我们观察到 DIS3L2 对全长转录物起作用，通过一个也涉及 UPF1 的过程。此外，DIS3L2 介导的衰变依赖于末端尿苷转移酶 Zcchc6/11 (TUT7/4) 的活性。总之，我们的发现确立了 DIS3L2 和尿苷化在 NMD 中的作用。
