The p120(ctn)-binding partner Kaiso is a bi-modal DNA-binding protein that recognizes both a sequence-specific consensus and methylated CpG dinucleotides.
The p120(ctn)-binding partner Kaiso is a new member of the POZ-zinc finger family of transcription factors implicated in development and cancer. To understand the role of Kaiso in gene regulation and p120(ctn)-mediated signaling and adhesion, we sought to identify Kaiso-specific DNA binding sequences and potential target genes. Here we demonstrate that Kaiso is a dual specificity DNA-binding protein that recognizes the specific consensus sequence TCCTGCNA as well as methyl-CpG dinucleotides. A minimal core sequence CTGCNA was identified as sufficient for Kaiso binding. Two copies of the Kaiso-binding site are present in the human and murine matrilysin promoters, implicating matrilysin as a candidate target gene for Kaiso. In electrophoretic mobility shift assays, matrilysin promoter-derived oligonucleotide probes formed a complex with GST-Kaiso fusion proteins possessing the zinc finger domain but not with fusion proteins lacking the zinc fingers. We further determined that only Kaiso zinc fingers 2 and 3 were necessary and sufficient for sequence-specific DNA binding. Interestingly, Kaiso also possesses a methyl-CpG-dependent DNA-binding activity distinct from its sequence-specific DNA binding. However, Kaiso has a higher affinity for the TCCTGCNA consensus than for the methyl-CpG sites. Furthermore, the DNA-binding ability of Kaiso with either recognition site was inhibited by p120(ctn). Kaiso thus appears to have two modes of DNA binding and transcriptional repression, both of which may be modulated by its interaction with the adhesion cofactor p120(ctn).
Daniel
Juliet M
JM
Department of Biology, LSB-331, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada. danielj@mcmaster.ca
Spring
Christopher M
CM
Crawford
Howard C
HC
Reynolds
Albert B
AB
Baig
Akeel
A
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D001667:Binding, Competitive; D051177:Catenins; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D018899:CpG Islands / Q000235:genetics*; D004247:DNA / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D006801:Humans; D020783:Matrix Metalloproteinase 7 / Q000235:genetics; D051379:Mice; D009841:Oligonucleotides / Q000235:genetics / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D000071999:S100 Calcium-Binding Protein A4; D009418:S100 Proteins / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D000095002:Delta Catenin
D051177:Catenins; D015815:Cell Adhesion Molecules; D004268:DNA-Binding Proteins; D009841:Oligonucleotides; D010750:Phosphoproteins; D000071999:S100 Calcium-Binding Protein A4; D009418:S100 Proteins; C470944:S100a4 protein, mouse; D014157:Transcription Factors; C492254:ZBTB33 protein, human; C118822:Zbtb33 protein, mouse; C077591:S100A4 protein, human; D004247:DNA; D020783:Matrix Metalloproteinase 7; D000095002:Delta Catenin