title: KLF4 interacts with beta-catenin/TCF4 and blocks p300/CBP recruitment by beta-catenin.
abstract: Wnt signaling is crucial in the organization and maintenance of the human intestinal epithelium, and somatic mutations that result in deregulated Wnt signaling are an early event in the development of colorectal cancer. The Wnt ligand ultimately results in the stabilization of cytoplasmic beta-catenin, which is then free to enter the nucleus and activate transcription through its interaction with the transcription factor TCF4. Our laboratory recently found that KLF4, a transcription factor highly expressed in the adult intestine and critical for intestinal differentiation, interacts with beta-catenin and inhibits Wnt signaling. In this study, we characterize the molecular mechanisms of KLF4-mediated inhibition of Wnt/beta-catenin signaling. We find that the KLF4 directly interacts with the C-terminal transactivation domain of beta-catenin and inhibits p300/CBP recruitment by beta-catenin. KLF4 inhibits p300/CBP-mediated beta-catenin acetylation as well as histone acetylation on Wnt target genes. In addition, we observe that KLF4 directly interacts with TCF4 independently of beta-catenin and that KLF4 and TCF4 are expressed in similar patterns within the large intestine, with greatest staining near the epithelial surface. These results provide a deeper understanding of the regulation of beta-catenin in the intestine and will have important implications in cancer and stem cell research.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas 77555, USA.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Evans
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
authors.forename: Wen
authors.initials: W
authors.lastname: Zhang
authors.forename: Chunming
authors.initials: C
authors.lastname: Liu
mesh_terms: D000107:Acetylation; D000818:Animals; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000378:metabolism*; D045744:Cell Line, Tumor; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000166:cytology; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000378:metabolism*; D051379:Mice; D017434:Protein Structure, Tertiary; D015398:Signal Transduction / Q000502:physiology; D000073940:Transcription Factor 4; D014162:Transfection; D051153:Wnt Proteins / Q000378:metabolism*; D051176:beta Catenin / Q000378:metabolism*
chemical_list: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; C000715467:KLF4 protein, human; C000715468:Klf4 protein, mouse; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; C090743:Tcf4 protein, mouse; D000073940:Transcription Factor 4; D051153:Wnt Proteins; D051176:beta Catenin