Identification of Tcf4 residues involved in high-affinity beta-catenin binding

Biochem Biophys Res Commun. 1999 Mar 24;256(3):584-90. doi: 10.1006/bbrc.1999.0379.

Abstract

The N-termini of members of the T-cell factor (Tcf) and lymphocyte-enhancement factor (Lef) protein families bind to beta-catenin, forming bipartite transcription factors which regulate expression of genes involved in organismal development and the growth of normal and malignant colon epithelium. Elevated levels of Tcf4:beta-catenin are found in colon tumor cells with mutations in the adenomatous polyposis coli (APC) gene. The elevated levels of Tcf4:beta-catenin result in increased transcription of genes, including c-myc, important for the growth of these tumor cells. Here we analyze the interaction between beta-catenin and Tcf4 and show that the N-terminal 53 amino acids of Tcf4 bind with high affinity to beta-catenin. We show that this high-affinity interaction involves multiple contact points including Tcf4 Asp-16, which is essential for beta-catenin binding. In addition to Tcf/Lef family members, beta-catenin binds to APC and cadherins. We found that the binding of beta-catenin to Tcf4, APC, or E-cadherin was mutually exclusive. These results are discussed with regard to how beta-catenin interacts with its binding partners and to the potential for identifying specific, small molecule inhibitors of these interactions.

MeSH terms

  • Adenomatous Polyposis Coli Protein
  • Amino Acid Sequence
  • Amino Acid Substitution
  • Amino Acids / analysis
  • Amino Acids / genetics
  • Amino Acids / metabolism*
  • Aspartic Acid / genetics
  • Aspartic Acid / metabolism
  • Binding, Competitive
  • Cadherins / chemistry
  • Cadherins / genetics
  • Cadherins / metabolism
  • Conserved Sequence
  • Cytoskeletal Proteins / chemistry
  • Cytoskeletal Proteins / genetics
  • Cytoskeletal Proteins / metabolism*
  • Enzyme-Linked Immunosorbent Assay
  • Humans
  • Inhibitory Concentration 50
  • Leucine / genetics
  • Leucine / metabolism
  • Molecular Sequence Data
  • Protein Binding
  • Protein Structure, Secondary
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Sequence Deletion
  • Solubility
  • TCF Transcription Factors
  • Trans-Activators*
  • Transcription Factor 7-Like 2 Protein
  • Transcription Factors / chemistry
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • beta Catenin

Substances

  • Adenomatous Polyposis Coli Protein
  • Amino Acids
  • CTNNB1 protein, human
  • Cadherins
  • Cytoskeletal Proteins
  • Recombinant Fusion Proteins
  • TCF Transcription Factors
  • TCF7L2 protein, human
  • Trans-Activators
  • Transcription Factor 7-Like 2 Protein
  • Transcription Factors
  • beta Catenin
  • Aspartic Acid
  • Leucine