Centromere Integrity and Cytoskeletal Function in Oocyte Aneuploidy and Reproductive Aging

About This Grant

PROJECT SUMMARY Chromosome segregation errors in mammalian oocytes are a leading cause of infertility, miscarriage, and developmental conditions such as Down syndrome. These errors increase significantly with maternal age and highlight the unique vulnerabilities of the oocyte: prolonged arrest, acentrosomal spindle assembly, and epigenetically maintained chromatin. Although the loss of chromosome cohesion during advancing maternal age has long been considered an explanation, it occurs gradually with age and is unlikely to account for the near- exponential rise in aneuploidy observed at advanced reproductive ages. Our findings, alongside those of others, demonstrate that cytoskeletal disorganization alone is sufficient to trigger premature sister chromatid separation and that even young oocytes, which maintain robust cohesion, frequently exhibit segregation errors. This proposal focuses on the centromere as a dynamic regulatory hub that coordinates kinetochore assembly and spindle attachment, as well as on the spindle as a structural system that provides a buffer against centromere dysfunction. Our central hypothesis posits that meiotic fidelity relies on the integrity of the centromere- cytoskeleton axis and that its age-sensitive breakdown leads to chromosome segregation errors. Using mouse oocytes, we will integrate TRIM-Away-mediated protein depletion, synthetic oocyte aging platforms, and quantitative high-resolution live imaging assays to analyze how centromere proteins (e.g., CENP-A, CENP-C), centromeric DNA composition, and microtubule-associated proteins (MAPs) interact to protect chromosome segregation. Aim 1 will identify how CENP-A and downstream kinetochore components support kinetochore function and spindle assembly checkpoint signaling. Aim 2 will reveal how differences in centromeric DNA and the CENP-B–CENP-C axis contribute to chromosome-specific missegregation risk. Aim 3 will explore how MAPs maintain spindle structure and compensate for compromised centromeres in aging oocytes. These studies will demonstrate how centromeric weakening, chromatin asymmetries, and spindle disorganization collectively undermine meiotic fidelity in aged oocytes. This research reframes reproductive aging as a failure of an integrated chromatin–cytoskeletal system, highlighting new molecular targets to mitigate age-related fertility decline. By combining conceptual innovation with cutting-edge experimental tools in live oocytes, our approach presents a powerful strategy to uncover the molecular origins of aneuploidy and enhance opportunities for intervention in reproductive aging.