Dimerization contributes to oncogenic activation of MLL chimeras in acute leukemias

• Published in: Cancer cell Vol. 4; no. 2; pp. 99 - 110
• Main Authors: So, Chi Wai, Lin, Min, Ayton, Paul M, Chen, Everett H, Cleary, Michael L
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.08.2003
• Subjects: Acute Disease; Adaptor Proteins, Signal Transducing; Animals; Calcium-Binding Proteins - chemistry; Calcium-Binding Proteins - genetics; Calcium-Binding Proteins - metabolism; Cell Line; Cell Transformation, Neoplastic; Cercopithecus aethiops; COS Cells; Dimerization; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Gene Expression Regulation, Neoplastic; Histone Methyltransferases; Histone-Lysine N-Methyltransferase; Homeodomain Proteins; Humans; Intracellular Signaling Peptides and Proteins; Leukemia - genetics; Leukemia - metabolism; Leukemia - pathology; Methyltransferases - chemistry; Methyltransferases - genetics; Methyltransferases - metabolism; Mice; Mice, Inbred C57BL; Myeloid-Lymphoid Leukemia Protein; Nerve Tissue Proteins - chemistry; Nerve Tissue Proteins - genetics; Nerve Tissue Proteins - metabolism; Phosphoproteins - chemistry; Phosphoproteins - genetics; Phosphoproteins - metabolism; Protein Methyltransferases; Protein Structure, Tertiary; Proto-Oncogenes; Recombinant Fusion Proteins - chemistry; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Survival Rate; Trans-Activators - genetics; Transcription Factors; Transcriptional Activation
• ISSN: 1535-6108; 1878-3686
• DOI: 10.1016/S1535-6108(03)00188-0

MLL is a histone methyltransferase that can be converted into an oncoprotein by acquisition of transcriptional effector domains following heterologous protein fusions with a variety of nuclear transcription factors, cofactors, or chromatin remodeling proteins in acute leukemias. Here we demonstrate an alternative mechanism for activation of MLL following fusions with proteins (AF1p/Eps15 and GAS7) that normally reside in the cytoplasm. The coiled-coil oligomerization domains of these proteins are necessary and sufficient for leukemogenic transformation induced by the respective MLL fusion proteins. Furthermore, homodimerization of MLL by synthetic dimerization modules mimics bona fide MLL fusion proteins resulting in Hox gene activation and enhanced self-renewal of hematopoietic progenitors. Our studies support an oligomerization-dependent mechanism for oncogenic conversion of MLL, presumably in part by recruitment of accessory factors through the dimerized MLL moiety of the chimeric protein.