The pluripotency of stem cells determines their developmental potential. While the pluripotency states of pluripotent stem cells are variable and interconvertible, the mechanisms underlying the acquisition and maintenance of pluripotency remain largely elusive. Here, we identified that methylenetetrahydrofolate dehydrogenase (NAD⁺-dependent), methenyltetrahydrofolate cyclohydrolase (Mthfd2) plays an essential role in maintaining embryonic stem cell pluripotency and promoting complete reprogramming of induced pluripotent stem cells. Mechanistically, in mitochondria, Mthfd2 maintains the integrity of the mitochondrial respiratory chain and prevents mitochondrial dysfunction. In the nucleus, Mthfd2 stabilizes the phosphorylation of EXO1 to support DNA end resection and promote homologous recombination repair. Our results revealed that Mthfd2 is a dual-function factor in determining the pluripotency of pluripotent stem cells through both mitochondrial and nuclear pathways, ultimately ensuring safe application of pluripotent stem cells.

干细胞的多能性决定了它们的发展潜力。尽管多能干细胞的多能状态是可变的并且可以相互转换，但是获得和维持多能性的基础机制仍然很难捉摸。在这里，我们发现亚甲基四氢叶酸脱氢酶（NAD ⁺依赖），亚甲基四氢叶酸环化酶（Mthfd2）在维持胚胎干细胞多能性和促进诱导性多能干细胞的完全重编程中起着至关重要的作用。从机制上讲，在线粒体中，Mthfd2保持线粒体呼吸链的完整性并防止线粒体功能障碍。在细胞核中，Mthfd2稳定EXO1的磷酸化以支持DNA末端切除并促进同源重组修复。我们的结果表明，Mthfd2是通过线粒体和核途径确定多能干细胞的多能性的双重功能因子，最终确保了多能干细胞的安全应用。