CHK1 Controls Zygote Pronuclear Envelope Breakdown by Regulating F-Actin Through Interacting With MICAL3

CHK1 mutations could cause zygote arrest at pronuclei stage that is poorly understood at molecular level. In the current study, by transferring the pre-pronuclei from CHK1-mutation zygotes into the cytoplasm of normal enucleated fertilized eggs, we could successfully rescue mutation-caused zygote arrest and harvest high-quality blastocysts,which indicates that CHK1 dysfunction may tremendously destroy biological events mainly in the cytoplasm. We then found that CHK1 mutants affected the F-actin meshwork to disturb pronuclear envelope breakdown. By collecting 6000 mouse zygotes for Co-immunoprecipitation/Mass spectrum, we further identified that CHK1 interacted with MICAL3, a vital regulator of F-actin disassembly. While CHK1 mutants enhanced the interaction with MICAL3 and thus increased MICAL3 enzyme activity, resulting in excessive F-actin depolymerization. This study supplies an interpretation for the regulatory mechanism of pronuclear envelope breakdown during the transition from meiosis to the first mitosis in mammalian.Funding Information: This research was supported by the National Natural Science Foundation of China (82171842, 81871168, 31871509), the National Key Research and Development Program of China (2018YFC1004000), the Basic Science Center Program of NSFC (31988101), the Foundation for Distinguished Young Scholars of Shandong Province (JQ201816), the Innovative Research Team of High-Level Local Universities in Shanghai (SHSMU-ZLCX20210200.Declaration of Interests: The authors declare no competing interests.Ethics Approval Statement: All subjects signed informed consents, and this study was reviewed and approved by the Institutional Review Board of Reproductive Medicine, Shandong University.The protocol for the animal study was reviewed and approved by the Institutional Review Board of Reproductive Medicine, Shandong University.