Chromosome translocations involving the mixed lineage leukemia gene MLL are associated with aggressive acute leukemias in both children and adults. Leukemogenic MLL fusion proteins delete the MLL SET domain Lys(4) methyltransferase activity and fuse MLL to 1 of >40 different translocation partners. Some MLL fusion proteins involve nuclear proteins that are transcriptional activators, whereas others have transcriptional activating activity but instead dimerize the truncated MLL molecule. Both types of MLL fusion proteins enforce persistent expression of Hox a9 and Meis1, which is pivotal for leukemogenesis through mechanisms that remain obscure. Here, we show that nuclear and dimerizable forms of MLL bind with a similar pattern to the Hox a9 locus that overlaps the distribution of wild-type MLL and deregulate transcription of three isoforms of Hox a9. Induction of MLL fusion protein activity is associated with increased levels of histone acetylation and Lys(4) methylation at Hox target genes. In addition, the MLL-ENL-ER protein, but not dimerized MLL, also induces dimethylation of histone H3 at Lys(79), suggesting alternative mechanisms for transcriptional activation.
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http://dx.doi.org/10.1158/0008-5472.CAN-05-1041 | DOI Listing |
Cancers (Basel)
January 2025
Hematology Unit, S. Eugenio Hospital (ASL Roma 2), 00122 Rome, Italy.
Menin (MEN1) is a well-recognized powerful tumor promoter in acute leukemias (AL) with KMT2A rearrangements (KMT2Ar, also known as MLL) and mutant nucleophosmin 1 (NPM1m) acute myeloid leukemia (AML). MEN1 is essential for sustaining leukemic transformation due to its interaction with wild-type KMT2A and KMT2A fusion proteins, leading to the dysregulation of KMT2A target genes. MEN1 inhibitors (MIs), such as revumenib, ziftomenib, and other active small molecules, represent a promising new class of therapies currently under clinical development.
View Article and Find Full Text PDFSheng Li Xue Bao
December 2024
State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Haihe Laboratory of Cell Ecosystem, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China.
The objective of the present study was to investigate the role and mechanism of bone marrow microenvironmental cells in regulating the mitochondrial mass of leukemia cells, and to uncover the mechanism of leukemia progression at the metabolic level. A mouse model of acute myeloid leukemia (AML) induced by the overexpression of the MLL-AF9 (MA9) fusion protein was established, and the bone marrow cells of AML mice were transplanted into mitochondrial fluorescence reporter mice expressing the Dendra2 protein (mito-Dendra2 mice). The proportion of Dendra2 cells in bone marrow leukemia cells at different stages of AML was quantified by flow cytometry.
View Article and Find Full Text PDFUnderstanding the molecular pathogenesis of MLL fusion oncoprotein (MLL-FP) leukaemia has spawned epigenetic therapies that have improved clinical outcomes in this often-incurable disease. Using genetic and pharmacological approaches, we define the individual and combined contribution of KAT6A, KAT6B and KAT7, in MLL-FP leukaemia. Whilst inhibition of KAT6A/B is efficacious in some pre-clinical models, simultaneous targeting of KAT7, with the novel inhibitor PF-9363, increases the therapeutic efficacy.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
Epigenetics Research Laboratory, Institute of Nano Science and Technology, Knowledge City, Sector 81, Mohali, Punjab 140306, India.
The heterogeneous form of malignancy in the myeloid lineage of normal hematopoietic stem cells (HSCs) is characterized as acute myeloid leukemia (AML). The t(9;11) reciprocal translocation (p22;q23) generates MLL-AF9 oncogene, which results in myeloid-based monoblastic AML with frequent relapse and poor survival. MLL-AF9 binds with the C-Myb promoter and regulates AML onset, maintenance, and survival.
View Article and Find Full Text PDFBlood Adv
December 2024
Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States.
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