Abstract：
Mouse embryonic stem cells (mESCs) sporadically transition to a transient totipotent state that resembles blastomeres of the two-cell (2C) embryo stage, which has been proposed to contribute to exceptional genomic stability, one of the key features of mESCs. However, the biological significance of the rare population of 2C-like cells (2CLCs) in ESC cultures remains to be tested. Here we generated an inducible reporter cell system for specific elimination of 2CLCs from the ESC cultures to disrupt the equilibrium between ESCs and 2CLCs. We show that removing 2CLCs from the ESC cultures leads to dramatic accumulation of DNA damage, genomic mutations, and rearrangements, indicating impaired genomic instability. Furthermore, 2CLCs removal results in increased apoptosis and reduced proliferation of mESCs in both serum/LIF and 2i/LIF culture conditions. Unexpectedly, p53 deficiency results in defective response to DNA damage, leading to early accumulation of DNA damage, micronuclei, indicative of genomic instability, cell apoptosis, and reduced self-renewal capacity of ESCs when devoid of 2CLCs in cultures. Together, our data reveal that transition to the privileged 2C-like state is a major component of the intrinsic mechanisms that maintain the exceptional genomic stability of mESCs for long-term self-renewal.
摘要：
小鼠胚胎干细胞（mESCs）偶尔过渡到类似于双细胞（2C）胚胎阶段的卵裂球的瞬时全能状态，它被认为有助于非凡的基因组稳定性，mESC的关键特征之一。然而,ESC培养物中2C样细胞（2CLC）的稀有群体的生物学意义仍有待测试。在这里，我们产生了一种诱导型报告细胞系统，用于从ESC培养物中特异性消除2CLC，以破坏ESC和2CLC之间的平衡。我们表明，从ESC培养物中去除2CLC会导致DNA损伤的急剧积累，基因组突变，和重新安排，表明基因组不稳定性受损。此外，2CLC去除导致在血清/LIF和2i/LIF培养条件下mESC的凋亡增加和增殖减少。出乎意料的是,p53缺陷导致对DNA损伤的反应缺陷，导致DNA损伤的早期积累，微核,表明基因组不稳定，细胞凋亡，培养物中缺乏2CLC时，ESC的自我更新能力降低。一起,我们的数据显示,向特权2C样状态的转变是维持mESCs长期自我更新的特殊基因组稳定性的内在机制的主要组成部分.
