DRP004383
HMGA2 blocks local expansion of Polycomb domains and timed repression of neurogenic genes
During normal development, cells become gradually and irreversibly committed to their specific fate and lose the potential to generate other cell types. Polycomb group proteins (PcG) play a central role in repressing lineage specific genes and limiting differentiation capacity of stem cell during development. Although PcG repress their target genes dynamically during development through Histone H3K27trimethylation (H3K27me3), it is unclear what triggers PcG mediated repression. Here we found that the timed local expansion of H3K27me3 domain into the gene coding regions triggers the timed repression of neurogenic genes at the end of the neurogenic phase. We found that H3K27me3 marks already reside at the upstream intergenic regions even when these genes are expressed. The timed expansion of these H3K27me3 in the late developmental stage is mediated by the release of HMGA proteins, which bind to the border of the H3K27me3 domain in early stages.