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Proc Natl Acad Sci U S A. 2016 Apr 5;113(14):3826-31. doi: 10.1073/pnas.1520926113. Epub 2016 Mar 21.

Combgap contributes to recruitment of Polycomb group proteins in Drosophila.

Author information

1
Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892;
2
Proteomics Centre, Erasmus University Medical Center, 3015 GE Rotterdam, The Netherlands; Department of Cell Biology, Erasmus University Medical Center, 3015 GE Rotterdam, The Netherlands.
3
Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892; jkassis@mail.nih.gov.

Abstract

Polycomb group (PcG) proteins are responsible for maintaining the silenced transcriptional state of many developmentally regulated genes. PcG proteins are organized into multiprotein complexes that are recruited to DNA via cis-acting elements known as "Polycomb response elements" (PREs). In Drosophila, PREs consist of binding sites for many different DNA-binding proteins, some known and others unknown. Identification of these DNA-binding proteins is crucial to understanding the mechanism of PcG recruitment to PREs. We report here the identification of Combgap (Cg), a sequence-specific DNA-binding protein that is involved in recruitment of PcG proteins. Cg can bind directly to PREs via GTGT motifs and colocalizes with the PcG proteins Pleiohomeotic (Pho) and Polyhomeotic (Ph) at the majority of PREs in the genome. In addition, Cg colocalizes with Ph at a number of targets independent of Pho. Loss of Cg leads to decreased recruitment of Ph at only a subset of sites; some of these sites are binding sites for other Polycomb repressive complex 1 (PRC1) components, others are not. Our data suggest that Cg can recruit Ph in the absence of PRC1 and illustrate the diversity and redundancy of PcG protein recruitment mechanisms.

KEYWORDS:

Combgap; PREs; PcG recruitment; Polycomb; gene expression

PMID:
27001825
PMCID:
PMC4833261
DOI:
10.1073/pnas.1520926113
[Indexed for MEDLINE]
Free PMC Article

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