The human candidate tumor suppressor gene HIC1 recruits CtBP through a degenerate GLDLSKK motif.
HIC1 (hypermethylated in cancer) and its close relative HRG22 (HIC1-related gene on chromosome 22) encode transcriptional repressors with five C(2)H(2) zinc fingers and an N-terminal BTB/POZ autonomous transcriptional repression domain that is unable to recruit histone deacetylases (HDACs). Alignment of the HIC1 and HRG22 proteins from various species highlighted a perfectly conserved GLDLSKK/R motif highly related to the consensus CtBP interaction motif (PXDLSXK/R), except for the replacement of the virtually invariant proline by a glycine. HIC1 strongly interacts with mCtBP1 both in vivo and in vitro through this conserved GLDLSKK motif, thus extending the CtBP consensus binding site. The BTB/POZ domain does not interact with mCtBP1, but the dimerization of HIC1 through this domain is required for the interaction with mCtBP1. When tethered to DNA by fusion with the Gal4 DNA-binding domain, the HIC1 central region represses transcription through interactions with CtBP in a trichostatin A-sensitive manner. In conclusion, our results demonstrate that HIC1 mediates transcriptional repression by both HDAC-independent and HDAC-dependent mechanisms and show that CtBP is a HIC1 corepressor that is recruited via a variant binding site.
Deltour
Sophie
S
CNRS UMR 8526, Institut de Biologie de Lille, Institut Pasteur de Lille, 59017 Lille Cedex, France.
Pinte
Sébastien
S
Guerardel
Cateline
C
Wasylyk
Bohdan
B
Leprince
Dominique
D
D000429:Alcohol Oxidoreductases; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D019556:COS Cells / Q000378:metabolism; D022003:Cell Nucleus Structures / Q000378:metabolism; D002478:Cells, Cultured; D017124:Conserved Sequence; D006224:Cricetinae; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D019143:Evolution, Molecular; D016147:Genes, Tumor Suppressor; D006655:Histone Deacetylases / Q000378:metabolism; D006801:Humans; D051741:Kruppel-Like Transcription Factors; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D011817:Rabbits; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
D004268:DNA-Binding Proteins; C096870:Hic1 protein, mouse; D051741:Kruppel-Like Transcription Factors; D010750:Phosphoproteins; D012097:Repressor Proteins; D014157:Transcription Factors; D000429:Alcohol Oxidoreductases; C096794:C-terminal binding protein; D006655:Histone Deacetylases