Ring1B compacts chromatin structure and represses gene expression independent of histone ubiquitination.
Mol Cell, 2010/5/14;38(3):452-64.
Eskeland R[1], Leeb M, Grimes GR, Kress C, Boyle S, Sproul D, Gilbert N, Fan Y, Skoultchi AI, Wutz A, Bickmore WA
Affiliations
PMID: 20471950DOI: 10.1016/j.molcel.2010.02.032
Impact factor: 19.328
Abstract
How polycomb group proteins repress gene expression in vivo is not known. While histone-modifying activities of the polycomb repressive complexes (PRCs) have been studied extensively, in vitro data have suggested a direct activity of the PRC1 complex in compacting chromatin. Here, we investigate higher-order chromatin compaction of polycomb targets in vivo. We show that PRCs are required to maintain a compact chromatin state at Hox loci in embryonic stem cells (ESCs). There is specific decompaction in the absence of PRC2 or PRC1. This is due to a PRC1-like complex, since decompaction occurs in Ring1B null cells that still have PRC2-mediated H3K27 methylation. Moreover, we show that the ability of Ring1B to restore a compact chromatin state and to repress Hox gene expression is not dependent on its histone ubiquitination activity. We suggest that Ring1B-mediated chromatin compaction acts to directly limit transcription in vivo.
MeSH terms
Acetylation; Animals; Cell Differentiation; Cell Line; Chromatin Assembly and Disassembly; Down-Regulation; Embryonic Stem Cells; Histones; Homeodomain Proteins; Methylation; Mice; Mutation; Polycomb Repressive Complex 1; Polycomb Repressive Complex 2; Polycomb-Group Proteins; Protein Processing, Post-Translational; Repressor Proteins; Transcription, Genetic; Ubiquitin-Protein Ligases; Ubiquitination
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