During the S phase of mitosis, Sororin is recruited by acetylated Smc3 and stabilizes sister chromatid cohesion by counteracting the Wapl-Pds5 interaction. Thereafter, Sororin is phosphorylated during prophase and translocated to the cytoplasm, where its function remains poorly understood. Here, we report that Sororin acts as a regulator of meiotic G₂-M transition and spindle assembly in mammalian oocytes. Sororin is present in the nucleus of GV oocytes and becomes associated with the spindle apparatus during meiosis I in mice. Depletion of Sororin causes failure of GVBD due to inactivation of Cdk1 and defective spindle assembly because of reduced levels of Cyclin B2. We validate Sororin interactions with Cyclin B2 that protects it from destruction by APC^Cdh1, which drives M phase entry and bipolar spindle formation. Notably, the meiotic functions of Sororin are conserved among mammals. Together, our findings provide novel insights into the noncanonical role of Sororin in the resumption of meiosis and progression through meiosis I in mammalian oocytes.

中文翻译：

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内聚素稳定剂 Sororin 驱动哺乳动物卵母细胞中的 G2-M 转换和纺锤体组装

在有丝分裂的 S 期，Sororin 被乙酰化 Smc3 募集，并通过抵消 Wapl-Pds5 相互作用来稳定姐妹染色单体的凝聚力。此后，索罗林在前期被磷酸化并转移到细胞质，其功能仍然知之甚少。在这里，我们报告 Sororin 作为哺乳动物卵母细胞中减数分裂 G ₂ -M 转换和纺锤体组装的调节剂。Sororin 存在于 GV 卵母细胞的细胞核中，并在小鼠减数分裂 I 期间与纺锤体相关。Sororin 的消耗导致 GVBD 的失败，这是由于 Cdk1 的失活和由于 Cyclin B2 水平的降低而导致的纺锤体组装缺陷。我们验证了 Sororin 与 Cyclin B2 的相互作用，以保护其免受 APC ^{Cdh1的破坏}，它驱动 M 相进入和双极纺锤体形成。值得注意的是，Sororin 的减数分裂功能在哺乳动物中是保守的。总之，我们的研究结果为 Sororin 在哺乳动物卵母细胞中通过减数分裂 I 恢复减数分裂和进展中的非规范作用提供了新的见解。