Binding to nonmethylated CpG DNA is essential for target recognition, transactivation, and myeloid transformation by an MLL oncoprotein.
The MLL gene is a frequent target for leukemia-associated chromosomal translocations that generate dominant-acting chimeric oncoproteins. These invariably contain the amino-terminal 1,400 residues of MLL fused with one of a variety of over 30 distinct nuclear or cytoplasmic partner proteins. Despite the consistent inclusion of the MLL amino-terminal region in leukemia oncoproteins, little is known regarding its molecular contributions to MLL-dependent oncogenesis. Using high-resolution mutagenesis, we identified three MLL domains that are essential for in vitro myeloid transformation via mechanisms that do not compromise subnuclear localization. These include the CXXC/Basic domain and two novel domains of unknown function. Point mutations in the CXXC domain that eliminate myeloid transformation by an MLL fusion protein also abolished recognition and binding of nonmethylated CpG DNA sites in vitro and transactivation in vivo. Our results define a critical role for the CXXC DNA binding domain in MLL-associated oncogenesis, most likely via epigenetic recognition of CpG DNA sites within the regulatory elements of target genes.
Ayton
Paul M
PM
Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA.
Chen
Everett H
EH
Cleary
Michael L
ML
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D001854:Bone Marrow Cells / Q000166:cytology; D019556:COS Cells; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002471:Cell Transformation, Neoplastic; D018899:CpG Islands; D003593:Cytoplasm / Q000378:metabolism; D004247:DNA / Q000737:chemistry / Q000235:genetics*; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D017353:Gene Deletion; D017930:Genes, Reporter; D011495:Histone-Lysine N-Methyltransferase; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D008856:Microscopy, Fluorescence; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D051788:Myeloid-Lymphoid Leukemia Protein; D010957:Plasmids / Q000378:metabolism; D017354:Point Mutation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011519:Proto-Oncogenes / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D015533:Transcriptional Activation; D014178:Translocation, Genetic
D004268:DNA-Binding Proteins; C497422:KMT2A protein, human; D014157:Transcription Factors; D051788:Myeloid-Lymphoid Leukemia Protein; D004247:DNA; D008156:Luciferases; D011495:Histone-Lysine N-Methyltransferase; C497423:Kmt2a protein, mouse