title: RFP represses transcriptional activation by bHLH transcription factors.
abstract: 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.
authors: Department of Haematology, Cambridge Institute for Medical Research, Cambridge University, Hills Road, Cambridge CB2 2XY, UK.
authors: Adrian J C
authors: AJ
authors: Bloor
authors: Ekaterina
authors: E
authors: Kotsopoulou
authors: Penny
authors: P
authors: Hayward
authors: Brian R
authors: BR
authors: Champion
authors: Anthony R
authors: AR
authors: Green
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000502:physiology*; D047468:Immunoprecipitation; D051379:Mice; D009687:Nuclear Proteins / Q000502:physiology*; D012097:Repressor Proteins / Q000502:physiology*; D014157:Transcription Factors / Q000502:physiology*; D015533:Transcriptional Activation / Q000502:physiology*; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases; D000070584:Tripartite Motif Proteins
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D044767:Ubiquitin-Protein Ligases; C489296:Trim27 protein, mouse; D000070584:Tripartite Motif Proteins