Cloning of a mammalian transcriptional activator that binds unmethylated CpG motifs and shares a CXXC domain with DNA methyltransferase, human trithorax, and methyl-CpG binding domain protein 1.
Ligand screening was utilized to isolate a human cDNA that encodes a novel CpG binding protein, human CpG binding protein (hCGBP). This factor contains three cysteine-rich domains, two of which exhibit homology to the plant homeodomain finger domain. A third cysteine-rich domain conforms to the CXXC motif identified in DNA methyltransferase, human trithorax, and methyl-CpG binding domain protein 1. A fragment of hCGBP that contains the CXXC domain binds to an oligonucleotide probe containing a single CpG site, and this complex is disrupted by distinct oligonucleotide competitors that also contain a CpG motif(s). However, hCGBP fails to bind oligonucleotides in which the CpG motif is either mutated or methylated, and it does not bind to single-stranded DNA or RNA probes. Furthermore, the introduction of a CpG dinucleotide into an unrelated oligonucleotide sequence is sufficient to produce a binding site for hCGBP. Native hCGBP is detected as an 88-kDa protein by Western analysis and is ubiquitously expressed. The DNA-binding activity of native hCGBP is apparent in electrophoretic mobility shift assays, and hCGBP trans-activates promoters that contain CpG motifs but not promoters in which the CpG is ablated. These data indicate that hCGBP is a transcriptional activator that recognizes unmethylated CpG dinucleotides, suggesting a role in modulating the expression of genes located within CpG islands.
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Herman B. Wells Center for Pediatric Research, Section of Pediatric Hematology/Oncology, Department of Pediatrics, Indianapolis, Indiana 46202, USA.
Carlone
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Jacobsen
B M
BM
Flodin
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A
Skalnik
D G
DG
D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000032:analysis / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D029721:Drosophila Proteins; D015894:Genome, Human; D006801:Humans; D008780:Methyltransferases / Q000235:genetics*; D008969:Molecular Sequence Data; D012097:Repressor Proteins / Q000235:genetics*; D016415:Sequence Alignment; D017421:Sequence Analysis; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C066141:MBD1 protein, human; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C063460:Trl protein, Drosophila; D008780:Methyltransferases