BioProject

Polycomb group (PcG) proteins mediate heritable but reversible silencing of developmental regulator genes by modifying their chromatin configuration. More...

Polycomb group (PcG) proteins mediate heritable but reversible silencing of developmental regulator genes by modifying their chromatin configuration. Accumulating evidence documents a role for PcG proteins in regulating higher order chromatin structures likely by their clustering, however, underlying mechanisms and its impact on transcriptional regulation remain obscure. In this study, we found that subnuclear clustering of PRC1 at canonical PcG target genes depended on head-to-tail polymerization property of SAM domain of Phc2 and likely Phc1. We show that Phc2-SAM polymerization limits the dynamic nature of PRC1, thereby promotes stable association of PRC1 with PcG target genes and contributes to their robust silencing. Our findings suggest a novel model by which SAM polymerization of Phc2 modulates the structural organization of PcG complexes to enable robust yet reversible PcG-mediated repression during development. Overall design: ChIP on chip analysis was carried out using the Mouse Promoter ChIP-on-chip Microarray Set (G4490A, Agilent, Palo Alto, Calif., USA). MEFs were subjected to ChIP assay using a Ring1B antibody. Purified immunoprecipitated and input DNA was subjected to T7 RNA polymerase-based amplification. Labeling, hybridization and washing were carried out according to the Agilent mammalian ChIP-on-chip protocol (ver.9.0). Scanned images were quantified with Agilent Feature Extraction software under standard conditions. Less...