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RFP represses transcriptional activation by bHLH transcription factors.

Basic helix-loop-helix (bHLH) transcription factors play a pivotal role in the regulation of tumorigenesis, and also in a wide range of other developmental processes in diverse species from yeast to humans. Here we demonstrate for the first time that Ret finger protein (RFP), a member of the TRIM family of proteins initially identified as a recombined transforming gene from a human lymphoma, is a novel interaction partner for four different bHLH proteins (SCL, E47, MyoD and mASH-1), but does not interact with GATA-1 or PU.1. Interaction with SCL required the B-box and first coiled-coil region of RFP together with the bHLH domain of SCL. RFP was able to repress transcriptional activation by E47, MyoD and mASH-1, but not by members of several other transcription factor families. Transcriptional repression by RFP was trichostatin A sensitive and did not involve an Id-like mechanism or ubiquitination with subsequent degradation of bHLH proteins. Instead, our results suggest that bHLH transcription factors are regulated by a previously undescribed interaction with RFP, which functions to recruit HDAC and/or Polycomb proteins and thus repress target genes of bHLH proteins. These results reveal an unexpected link between the bHLH and TRIM protein families.

Pubmed ID: 16007160


  • Bloor AJ
  • Kotsopoulou E
  • Hayward P
  • Champion BR
  • Green AR



Publication Data

October 13, 2005

Associated Grants

  • Agency: Wellcome Trust, Id:

Mesh Terms

  • Animals
  • Basic Helix-Loop-Helix Transcription Factors
  • Cell Line
  • DNA-Binding Proteins
  • Immunoprecipitation
  • Mice
  • Nuclear Proteins
  • Repressor Proteins
  • Transcription Factors
  • Transcriptional Activation
  • Two-Hybrid System Techniques