Laboratory of Reproductive Biology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan.
Reproduction. 2024 May 31;168(1). doi: 10.1530/REP-24-0079. Print 2024 Jul 1.
Proper early embryonic development in mammals relies on precise cellular signaling pathways. This study reveals that NSUN5 is crucial for the regulation of the Hippo pathway, ensuring normal proliferation and differentiation in mouse preimplantation embryos.
NOL1/NOP2/Sun domain family, member 5 (NSUN5) is an enzyme belonging to the 5-methylcytosine (m5C) writer family that modifies rRNA and mRNA. Our data revealed an upregulation of Nsun5 at the two-cell stage of mouse preimplantation development, suggesting its significance in early embryonic development. Given m5C's important role in stabilizing rRNA and mRNA and the Hippo signaling pathway's critical function in lineage segregation during embryogenesis, we hypothesized that NSUN5 controls cell differentiation by regulating the expression of components of the Hippo signaling pathway in mouse early embryos. To examine this hypothesis, we employed Nsun5-specific small interfering RNAs for targeted gene silencing in mouse preimplantation embryos. Nsun5 knockdown resulted in significant developmental impairments including reduced blastocyst formation, smaller size of blastocysts, and impaired hatching from the zona pellucida. Nsun5 knockdown also led to decreased cell numbers and increased apoptosis in embryos. We also observed diminished nuclear translocation of yes-associated protein 1 (YAP1) in Nsun5 knockdown embryos at the morula stage, indicating disrupted cell differentiation. This disruption was further evidenced by an altered ratio of CDX2-positive to OCT4-positive cells. Furthermore, Nsun5 depletion was found to upregulate the Hippo signaling-related key genes, Lats1 and Lats2 at the morula stage. Our findings underscore the essential role of Nsun5 in early embryonic development by affecting cell proliferation, YAP1 nuclear translocation, and the Hippo pathway.
哺乳动物胚胎的正常早期发育依赖于精确的细胞信号通路。本研究揭示，NSUN5 对 Hippo 通路的调控至关重要，确保了小鼠着床前胚胎的正常增殖和分化。
NOL1/NOP2/Sun 结构域家族成员 5（NSUN5）是一种酶，属于 5-甲基胞嘧啶（m5C）写入器家族，可修饰 rRNA 和 mRNA。我们的数据显示，NSUN5 在小鼠着床前胚胎发育的二细胞期上调，表明其在早期胚胎发育中的重要性。鉴于 m5C 在稳定 rRNA 和 mRNA 中的重要作用以及 Hippo 信号通路在胚胎发生过程中谱系分离中的关键作用，我们假设 NSUN5 通过调节 Hippo 信号通路组件的表达来控制细胞分化在小鼠早期胚胎中。为了检验这一假设，我们在小鼠着床前胚胎中使用了针对 Nsun5 的特异性小干扰 RNA 进行靶向基因沉默。Nsun5 敲低导致胚胎发育严重受损，包括囊胚形成减少、囊胚体积减小以及从透明带孵化受损。Nsun5 敲低还导致胚胎细胞数量减少和凋亡增加。我们还观察到 Nsun5 敲低胚胎在桑葚胚期 YAP1（yes-associated protein 1）核易位减少，表明细胞分化受到干扰。这种干扰进一步表现在 CDX2 阳性细胞与 OCT4 阳性细胞的比例改变。此外，在桑葚胚期发现 Nsun5 耗竭会上调 Hippo 信号相关关键基因 Lats1 和 Lats2。我们的研究结果强调了 Nsun5 通过影响细胞增殖、YAP1 核易位和 Hippo 通路在早期胚胎发育中的重要作用。
