MLL fusion proteins link transcriptional coactivators to previously active CpG-rich promoters.
Mixed-lineage leukemia (MLL) maintains the expression of cellular memory genes during development, while leukemic MLL fusion proteins aberrantly maintain expression of hematopoietic stem cell program genes such as HOXA9 to cause leukemia. However, the molecular mechanism of gene activation is unclear. Here we show that only two functional modules are necessary and sufficient for target recognition: those that bind to non-methylated CpGs and di-/tri-methylated histone H3 lysine 36 (H3K36me2/3). An artificial protein composed of the two targeting modules and an interaction domain for AF4-family coactivators can functionally substitute for MLL fusion proteins. Because H3K36me2/3 markers are indicative of active transcription, MLL fusion proteins target previously active CpG-rich genes and activate transcription by recruiting coactivators thereto. Our results indicate that such chromatin context-dependent gene activation is the fundamental mechanism by which MLL fusion proteins maintain the expression of the cellular memory/hematopoietic stem cell program genes.
Laboratory for Malignancy Control Research, Medical Innovation Center, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan, Division of Hematological Malignancy, National Cancer Center Research Institute, Tokyo 104-0045, Japan, Department of Molecular Oncology and Leukemia Program Project, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553, Japan and Department of Molecular Biology and Medicine, Laboratory for System Biology and Medicine (LSBM), Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Tokyo 153-8904, Japan.
Hiroshi
H
Okuda
Marie
M
Kawaguchi
Akinori
A
Kanai
Hirotaka
H
Matsui
Takeshi
T
Kawamura
Toshiya
T
Inaba
Issay
I
Kitabayashi
Akihiko
A
Yokoyama
D000818:Animals; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic; D018899:CpG Islands; D006657:Histones / Q000378:metabolism; D006801:Humans; D007942:Leukemia, Experimental / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D051788:Myeloid-Lymphoid Leukemia Protein / Q000737:chemistry / Q000378:metabolism*; D009707:Nucleosomes / Q000378:metabolism; D015514:Oncogene Proteins, Fusion / Q000737:chemistry / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D015534:Trans-Activators / Q000378:metabolism*; D015533:Transcriptional Activation
D006657:Histones; D009707:Nucleosomes; D015514:Oncogene Proteins, Fusion; D015534:Trans-Activators; D051788:Myeloid-Lymphoid Leukemia Protein