A potent transrepression domain in the retinoblastoma protein induces a cell cycle arrest when bound to E2F sites

Proc Natl Acad Sci U S A. 1995 Dec 5;92(25):11544-8. doi: 10.1073/pnas.92.25.11544.

Abstract

An intact T/E1A-binding domain (the pocket) is necessary, but not sufficient, for the retinoblastoma protein (RB) to bind to DNA-protein complexes containing E2F and for RB to induce a G1/S block. Indirect evidence suggests that the binding of RB to E2F may, in addition to inhibiting E2F transactivation function, generate a complex capable of functioning as a transrepressor. Here we show that a chimera in which the E2F1 transactivation domain was replaced with the RB pocket could, in a DNA-binding and pocket-dependent manner, mimic the ability of RB to repress transcription and induce a cell cycle arrest. In contrast, a transdominant negative E2F1 mutant that is capable of blocking E2F-dependent transactivation did not. Fusion of the RB pocket to a heterologous DNA-binding domain unrelated to E2F likewise generated a transrepressor protein when scored against a suitable reporter. These results suggest that growth suppression by RB is due, at least in part, to transrepression mediated by the pocket domain bound to certain promoters via E2F.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Base Sequence
  • Carrier Proteins*
  • Cell Cycle Proteins*
  • Cell Cycle*
  • Cells, Cultured
  • DNA / metabolism
  • DNA-Binding Proteins*
  • E2F Transcription Factors
  • E2F1 Transcription Factor
  • Humans
  • Molecular Sequence Data
  • Mutation
  • Peptide Fragments / genetics
  • Peptide Fragments / metabolism*
  • Promoter Regions, Genetic
  • Protein Binding
  • Protein Structure, Tertiary
  • Recombinant Fusion Proteins
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism*
  • Retinoblastoma Protein / genetics
  • Retinoblastoma Protein / metabolism*
  • Retinoblastoma-Binding Protein 1
  • Transcription Factor DP1
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Transcriptional Activation

Substances

  • Carrier Proteins
  • Cell Cycle Proteins
  • DNA-Binding Proteins
  • E2F Transcription Factors
  • E2F1 Transcription Factor
  • E2F1 protein, human
  • Peptide Fragments
  • Recombinant Fusion Proteins
  • Repressor Proteins
  • Retinoblastoma Protein
  • Retinoblastoma-Binding Protein 1
  • Transcription Factor DP1
  • Transcription Factors
  • DNA