Distinct roles of Cep192 and Cep152 in acentriolar MTOCs and spindle formation during mouse oocyte maturation

Mammalian oocytes lack a centriole that acts as a microtubule organization center (MTOC) in most somatic cells. During oocyte maturation, MTOCs undergo remodeling processes, including decondensation, fragmentation, and self-organization. However, the underlying mechanisms of MTOC remodeling in mouse oocytes are not well understood. We showed that two pericentriolar proteins, Cep192 and Cep152, play crucial roles during MTOC remodeling in mouse oocytes. Cep192 is present in MTOCs at all stages of oocyte maturation, and its depletion induces ablation of MTOCs, delay in spindle formation, and abnormal chromosomal alignment in spindles. In the case of Cep152, its localization on MTOCs is limited at the germinal vesicle stage and then disappears from the MTOCs after the germinal vesicle breakdown stage. Cep152 exclusion from MTOCs is involved in the fragmentation of MTOCs, and it is regulated by cyclin-dependent kinase 1 activity. Our results demonstrate the different roles of Cep192 and Cep152 in MTOC remodeling and a novel regulatory mechanism during meiotic spindle formation in mouse oocytes.