减数分裂
减数分裂II
生物
非整倍体
染色体分离
粘蛋白
遗传学
主轴检查点
同源染色体
染色体
卵母细胞
细胞生物学
动细胞
胚胎
基因
作者
Aleksandar I. Mihajlović,Candice Byers,Laura G. Reinholdt,Greg FitzHarris
标识
DOI:10.15252/embr.202357227
摘要
Abstract Chromosome segregation errors in mammalian oocyte meiosis lead to developmentally compromised aneuploid embryos and become more common with advancing maternal age. Known contributors include age‐related chromosome cohesion loss and spindle assembly checkpoint (SAC) fallibility in meiosis‐I. But how effective the SAC is in meiosis‐II and how this might contribute to age‐related aneuploidy is unknown. Here, we developed genetic and pharmacological approaches to directly address the function of the SAC in meiosis‐II. We show that the SAC is insensitive in meiosis‐II oocytes and that as a result misaligned chromosomes are randomly segregated. Whilst SAC ineffectiveness in meiosis‐II is not age‐related, it becomes most prejudicial in oocytes from older females because chromosomes that prematurely separate by age‐related cohesion loss become misaligned in meiosis‐II. We show that in the absence of a robust SAC in meiosis‐II these age‐related misaligned chromatids are missegregated and lead to aneuploidy. Our data demonstrate that the SAC fails to prevent cell division in the presence of misaligned chromosomes in oocyte meiosis‐II, which explains how age‐related cohesion loss can give rise to aneuploid embryos.
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