Maternal CENP-C restores centromere symmetry in mammalian zygotes to ensure proper chromosome segregation.

Abstract

Across metazoan species, the centromere-specific histone variant CENP-A is essential for accurate chromosome segregation, yet its regulation during the mammalian parental-to-zygote transition is poorly understood. To address this, we generated a CENP-A-mScarlet mouse model that revealed sex-specific dynamics: mature sperm retain 10% of the CENP-A levels present in MII oocytes. However, this difference is resolved in zygotes prior to the first mitosis, using maternally inherited cytoplasmic CENP-A. Notably, the increase in CENP-A at paternal centromeres is independent of sensing CENP-A asymmetry or the presence of maternal chromosomes. Instead, CENP-A equalization relies on the asymmetric recruitment of maternal CENP-C to paternal centromeres. Depletion of maternal CENP-A decreases total CENP-A in both pronuclei without disrupting equalization. In contrast, reducing maternal CENP-C or disruption of its dimerization function impairs CENP-A equalization and chromosome segregation. Therefore, maternal CENP-C acts as a key epigenetic regulator that resets centromeric symmetry at fertilization to preserve genome integrity.