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Mol Cell. 2010 May 14;38(3):452-64. doi: 10.1016/j.molcel.2010.02.032.

Ring1B compacts chromatin structure and represses gene expression independent of histone ubiquitination.

Author information

1
MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Crewe Road, Edinburgh EH4 2XU, UK.

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.

PMID:
20471950
PMCID:
PMC3132514
DOI:
10.1016/j.molcel.2010.02.032
[Indexed for MEDLINE]
Free PMC Article

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