This research program will elucidate the molecular mechanisms underlying the epigenetic inheritance of centromeres, an essential chromosomal landmark, defined by the histone H3 variant, Centromere Protein A (CENP-A) across animal generations. Centromeres are critical for accurate chromosome segregation and genome stability, marking the chromatin that serves as the attachment site for spindle microtubules during both mitosis and meiosis. Unlike other epigenetic marks that are erased during development, the centromeric CENPA mark must be stably inherited through animal generations through a yet unknown mechanism, to ensure genome integrity and species continuity. Understanding these mechanisms is vital, as errors in CENP-A inheritance can cause chromosomal instability (CIN), including aneuploidy. By bridging these gaps, this program will uncover how centromeric identity and size are maintained across generations, offering critical insights into the context-specific rules of chromosome segregation and epigenetic inheritance, with broader implications for developmental biology, and the prevention of chromosomal instability disorders.

Previous studies using cultured cells have established that centromere identity is maintained across somatic cell cycles via a “copying” mechanism, where pre-existing CENP-A nucleosomes direct their own assembly. While this well-established model explains somatic cell inheritance, recent findings challenge this paradigm in early embryonic divisions. In embryos, centromere asymmetry between maternal and paternal genomes arises due to unequal CENP-A levels, contradicting the copying mechanism. Embryos must rapidly equalize CENP-A levels, resolving asymmetry to unify the genomes and avoid genome instability, such as aneuploidy, associated with persistent asymmetry. The mechanisms of CENP-A equalization, including how an optimal centromere size is determined, are unknown and represent critical knowledge gaps that will be addressed in this research. Specifically, over the next 5 years, I will develop in vivo animal models using a dual hypothesis-driven and discovery-based approach to study the dynamic plasticity of centromere inheritance during embryonic divisions that tissue culture models cannot capture, focusing on:

1. Defining molecular mechanisms of CENP-A equalization between parental genomes.
2. Determining how embryos choose and establish a uniform centromere size optimized for proper chromosome segregation.

By moving beyond paradigms derived largely from cultured cell systems, this program will establish a foundational in vivo framework for centromere inheritance, transforming our understanding of how genome stability is safeguarded across generations and directly informing mechanisms underlying infertility, and related disorders.