Sparse CBX2 nucleates many Polycomb proteins to promote facultative heterochromatinization of Polycomb target genes.

ABSTRACT: Facultative heterochromatinization of genomic regulators by Polycomb repressive complex (PRC) 1 and 2 is essential in development and differentiation; however, the underlying molecular mechanisms remain obscure. Using genetic engineering, molecular approaches, and live-cell single-molecule imaging, we quantify the number of proteins within condensates formed through liquid-liquid phase separation (LLPS) and find that in mouse embryonic stem cells (mESCs), approximately 3 CBX2 proteins nucleate many PRC1 and PRC2 subunits to form one non-stoichiometric condensate. We demonstrate that sparse CBX2 prevents Polycomb proteins from migrating to constitutive heterochromatin, demarcates the spatial boundaries of facultative heterochromatin, controls the deposition of H3K27me3, regulates transcript

SUBMITTER: Ingersoll S 

PROVIDER: S-EPMC10871256 | biostudies-literature | 2024 Feb

REPOSITORIES: biostudies-literature