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  • The EMBO Journal (2002) 21, 4632 - 4640
  • doi:10.1093/emboj/cdf460

The chromatin remodeling complex NoRC targets HDAC1 to the ribosomal gene promoter and represses RNA polymerase I transcription

Yonggang Zhou1, Raffaella Santoro1 and Ingrid Grummt1

  1. Division of Molecular Biology of the Cell II, Deutsches Krebsforschungszentrum, D-69120 Heidelberg, Germany

Correspondence to:

Ingrid Grummt, E-mail: I.Grummt@dkfz.de

Received 6 March 2002; Accepted 16 July 2002; Revised 12 July 2002

Mammalian chromatin remodeling complexes are involved in both activation and repression of transcription. Here, we show that NoRC, a SNF2h- containing nucleolar chromatin remodeling complex, represses ribosomal gene transcription. NoRC-mediated rDNA silencing was alleviated by trichostatin A, indicating that histone deacetylation is causally involved in silencing. Chromatin immunoprecipitation experiments demonstrate that overexpression of TIP5, the large subunit of NoRC, mediates deacetylation of nucleosomes in the vicinity of the rDNA promoter. Protein–protein interaction assays reveal association of TIP5 with the histone deacetylase HDAC1 in vivo and in vitro. Deletion of the C-terminal PHD finger and bromodomain abolishes the interaction of TIP5 and HDAC1, and abrogates transcriptional repression. The results suggest that NoRC silences the rDNA locus by targeting the SIN3 corepressor complex to the rDNA promoter, thereby establishing a repressed chromatin structure.

  • Keywords:

    • histone modification,
    • RNA polymerase I,
    • silencing,
    • TIP5,
    • transcription