BCoR, a novel corepressor involved in BCL-6 repression

  1. Khanh D. Huynh1,
  2. Wolfgang Fischle4,
  3. Eric Verdin4, and
  4. Vivian J. Bardwell1,2,3,5
  1. 1Biochemistry, Molecular Biology, and Biophysics Program; 2Department of Genetics, Cell Biology, and Development; and 3Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455 USA; 4Gladstone Institute of Virology and Immunology, University of California, San Francisco, California 94103 USA

Abstract

BCL-6 encodes a POZ/zinc finger transcriptional repressor that is required for germinal center formation and may influence apoptosis. Aberrant expression ofBCL-6 due to chromosomal translocations is implicated in certain subtypes of non-Hodgkin's lymphoma. The POZ domains of BCL-6 and several other POZ proteins interact with corepressors N-CoR and SMRT. Here we identify and characterize a novel corepressor BCoR (BCL-6 interacting corepressor), which is expressed ubiquitously in human tissues. BCoR can function as a corepressor when tethered to DNA and, when overexpressed, can potentiate BCL-6 repression. Specific class I and II histone deacetylases (HDACs) interact in vivo with BCoR, suggesting that BCoR may functionally link these two classes of HDACs. Strikingly, BCoR interacts selectively with the POZ domain of BCL-6 but not with eight other POZ proteins tested, including PLZF. Additionally, interactions between the BCL-6 POZ domain and SMRT, N-CoR, and BCoR are mutually exclusive. The specificity of the BCL-6/BCoR interaction suggests that BCoR may have a role in BCL-6-associated lymphomas.

Keywords

Footnotes

  • 5 Corresponding author.

  • E-MAIL bardwell{at}lenti.med.umn.edu; FAX (612) 626-6140.

    • Received March 8, 2000.
    • Accepted May 23, 2000.
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