SMAR1 and Cux/CDP modulate chromatin and act as negative regulators of the TCRbeta enhancer (Ebeta)

Nucleic Acids Res. 2004 Sep 15;32(16):4862-75. doi: 10.1093/nar/gkh807. Print 2004.

Abstract

Chromatin modulation at various cis-acting elements is critical for V(D)J recombination during T and B cell development. MARbeta, a matrix-associated region (MAR) located upstream of the T cell receptor beta (TCRbeta) enhancer (Ebeta), serves a crucial role in silencing Ebeta-mediated TCR activation. By DNaseI hypersensitivity assays, we show here that overexpression of the MAR binding proteins SMAR1 and Cux/CDP modulate the chromatin structure at MARbeta. We further demonstrate that the silencer function of MARbeta is mediated independently by SMAR1 and Cux/CDP as judged by their ability to repress Ebeta-dependent reporter gene expression. Moreover, the repressor activity of SMAR1 is strongly enhanced in the presence of Cux/CDP. These two proteins physically interact with each other and colocalize within the perinuclear region through a SMAR1 domain required for repression. The repression domain of SMAR1 is separate from the MARbeta binding domain and contains a nuclear localization signal and an arginine-serine (RS)-rich domain, characteristic of pre-mRNA splicing regulators. Our data suggest that at the double positive stage of T cell development, cis-acting MARbeta elements recruit the strong negative regulators Cux and SMAR1 to control Ebeta-mediated recombination and transcription.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Cell Cycle Proteins / analysis
  • Cell Cycle Proteins / chemistry
  • Cell Cycle Proteins / physiology*
  • Cell Line, Tumor
  • Cell Nucleus / chemistry
  • Chromatin / chemistry*
  • DNA-Binding Proteins / analysis
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / physiology*
  • Enhancer Elements, Genetic*
  • Gene Silencing*
  • Homeodomain Proteins
  • Humans
  • Matrix Attachment Region Binding Proteins / chemistry
  • Matrix Attachment Region Binding Proteins / physiology
  • Mice
  • Molecular Sequence Data
  • Nuclear Proteins / analysis
  • Nuclear Proteins / chemistry
  • Nuclear Proteins / physiology*
  • Protein Structure, Tertiary
  • Receptors, Antigen, T-Cell, alpha-beta / genetics*
  • Regulatory Sequences, Nucleic Acid
  • Repressor Proteins / analysis
  • Repressor Proteins / physiology*
  • Transcription Factors
  • Transcription, Genetic

Substances

  • BANP protein, human
  • CUX1 protein, human
  • Cell Cycle Proteins
  • Chromatin
  • Cux1 protein, mouse
  • DNA-Binding Proteins
  • Homeodomain Proteins
  • Matrix Attachment Region Binding Proteins
  • Nuclear Proteins
  • Receptors, Antigen, T-Cell, alpha-beta
  • Repressor Proteins
  • SATB1 protein, human
  • Transcription Factors