State Key Laboratory of Microbial Technology, Shandong University, Qingdao Campus, Qingdao 266237, China.
School of Basic Medical Sciences, Hangzhou Normal University, Hangzhou 311121, China.
Biomolecules. 2024 Aug 17;14(8):1023. doi: 10.3390/biom14081023.
Nonsense-mediated mRNA decay (NMD) is a highly conserved post-transcriptional gene expression regulatory mechanism in eukaryotic cells. NMD eliminates aberrant mRNAs with premature termination codons to surveil transcriptome integrity. Furthermore, NMD fine-tunes gene expression by destabilizing RNAs with specific NMD features. Thus, by controlling the quality and quantity of the transcriptome, NMD plays a vital role in mammalian development, stress response, and tumorigenesis. Deficiencies of NMD factors result in early embryonic lethality, while the underlying mechanisms are poorly understood. SMG5 is a key NMD factor. In this study, we generated an conditional knockout mouse model and found that -null results in early embryonic lethality before E13.5. Furthermore, we produced multiple lines of knockout mouse embryonic stem cells (mESCs) and found that the deletion of in mESCs does not compromise cell viability. -null delays differentiation of mESCs. Mechanistically, our study reveals that the c-MYC protein, but not mRNA, is upregulated in SMG5-deficient mESCs. The overproduction of c-MYC protein could be caused by enhanced protein synthesis upon SMG5 loss. Furthermore, SMG5-null results in dysregulation of alternative splicing on multiple stem cell differentiation regulators. Overall, our findings underscore the importance of SMG5-NMD in regulating mESC cell-state transition.
无意义介导的 mRNA 降解（NMD）是真核细胞中一种高度保守的转录后基因表达调控机制。NMD 消除具有提前终止密码子的异常 mRNA，以监测转录组的完整性。此外，NMD 通过使具有特定 NMD 特征的 RNA 不稳定来精细调节基因表达。因此，通过控制转录组的质量和数量，NMD 在哺乳动物发育、应激反应和肿瘤发生中发挥着至关重要的作用。NMD 因子的缺乏会导致早期胚胎致死，但其潜在机制尚不清楚。SMG5 是一种关键的 NMD 因子。在这项研究中，我们生成了一个条件性敲除小鼠模型，发现 -/-导致 E13.5 之前的早期胚胎致死。此外，我们产生了多条 -/- 敲除小鼠胚胎干细胞（mESCs），并发现 mESCs 中 -/-并不影响细胞活力。-/- 延迟 mESCs 的分化。从机制上讲，我们的研究揭示了在 SMG5 缺陷型 mESCs 中，c-MYC 蛋白而不是 -/-mRNA 上调。SMG5 缺失后，c-MYC 蛋白的过度产生可能是由于蛋白质合成增强所致。此外，SMG5-/-导致多个干细胞分化调节剂的可变剪接失调。总的来说，我们的研究结果强调了 SMG5-NMD 在调节 mESC 细胞状态转变中的重要性。
