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Ezh1 and Ezh2 maintain repressive chromatin through different mechanisms.

Polycomb group proteins are critical to maintaining gene repression established during Drosophila development. Part of this group forms the PRC2 complex containing Ez that catalyzes di- and trimethylation of histone H3 lysine 27 (H3K37me2/3), marks repressive to transcription. We report that the mammalian homologs Ezh1 and Ezh2 form similar PRC2 complexes but exhibit contrasting repressive roles. While PRC2-Ezh2 catalyzes H3K27me2/3 and its knockdown affects global H3K27me2/3 levels, PRC2-Ezh1 performs this function weakly. In accordance, Ezh1 knockdown was ineffectual on global H3K27me2/3 levels. Instead, PRC2-Ezh1 directly and robustly represses transcription from chromatinized templates and compacts chromatin in the absence of the methyltransferase cofactor SAM, as evidenced by electron microscopy. Ezh1 targets a subset of Ezh2 genes, yet Ezh1 is more abundant in nonproliferative adult organs while Ezh2 expression is tightly associated with proliferation, as evidenced when analyzing aging mouse kidney. These results might reflect subfunctionalization of a PcG protein during evolution.

Pubmed ID: 19026781

Authors

  • Margueron R
  • Li G
  • Sarma K
  • Blais A
  • Zavadil J
  • Woodcock CL
  • Dynlacht BD
  • Reinberg D

Journal

Molecular cell

Publication Data

November 21, 2008

Associated Grants

  • Agency: NIGMS NIH HHS, Id: GM64844
  • Agency: Howard Hughes Medical Institute, Id:
  • Agency: Howard Hughes Medical Institute, Id:

Mesh Terms

  • Animals
  • Baculoviridae
  • Cell Line
  • Cell Line, Tumor
  • Chromatin
  • Chromatin Immunoprecipitation
  • DNA-Binding Proteins
  • Genes, Reporter
  • HeLa Cells
  • Histone-Lysine N-Methyltransferase
  • Humans
  • Immunohistochemistry
  • Jurkat Cells
  • Kidney
  • Luciferases
  • Mice
  • Mutation
  • NIH 3T3 Cells
  • Polycomb Repressive Complex 2
  • Promoter Regions, Genetic
  • Recombinant Proteins
  • Repressor Proteins
  • Transcription Factors
  • Transfection