A versatile cohesion manipulation system reveals CENP-A dysfunction accelerates female reproductive age-related egg aneuploidy.

Female reproductive aging is accompanied by a dramatic rise in the incidence of egg aneuploidy. Premature loss of chromosome cohesion proteins and untimely separation of chromosomes is thought to underly high rates egg aneuploidy during maternal aging. However, because chromosome cohesion loss occurs gradually over female reproductive lifespan and cytoskeletal defects alone can predispose eggs to chromosomal abnormalities, the root causes of exponential rise in egg aneuploidy at advanced reproductive ages remain a mystery. Here, we applied high-resolution live imaging to visualize for the first time cohesion protein dynamics underpinning meiotic chromosome segregation. To discover proteins whose dysfunction accelerates aneuploidies associated with female reproductive aging, we innovated the first experimental system in which chemically induced cohesion reduction rapidly triggers aging-like chromosomal abnormalities in young eggs. By integrating this direct cohesion manipulation system with quantitative high-resolution microscopy and targeted protein degradation tools, we identified the centromeric protein CENP-A as a new factor whose aging-like depletion causes a dramatic rise in premature separation of sister chromatids. Our work illuminates cohesion loss-independent origins of age-related egg aneuploidy and provides new avenues to discover therapeutic targets for extending the female reproductive lifespan.