Year: 2026
Type: article
Abstract: During early development, embryos undergo the maternal-to-zygotic transition (MZT), when control of development shifts from maternal factors to the newly activated zygotic genome. Decades of studies in various model organisms suggest that the nucleocytoplasmic (N/C) ratio is a key regulator of zygotic genome activation (ZGA), though this relationship is more nuanced in some organisms than others. Changing the nuclear content, nucleus size or cell size has been shown to shift the timing of ZGA. Mechanistically, the N/C ratio is linked to fundamental cellular processes that regulate genome activities, including nuclear import, repressor titration, activator accumulation, cell cycle lengthening, and chromatin remodeling. In this review, we summarize the experimental evidence supporting the N/C ratio as a regulator of ZGA and describe the associated molecular mechanisms. We also discuss the limitations of the N/C ratio model, highlight species-specific differences, and examine outstanding questions.
Authors: Lily Acker, Hui Chen
Institution: University of South Carolina
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $3,801
Funder: University of South Carolina
OpenAlex ID: W7147452009