Project description:Despite the impact of DNMT3A mutation in acute myeloid leukemia has been emphasized, the precise molecular mechanisms in leukemogenesis are largely unknown. Here we show that, in murine transplantation experiments, recipients transplanted with DNMT3A mutant-transduced cells exhibit aberrant hematopoietic stem cell (HSC) accumulation. Differentiation-associated genes are down-regulated without accompanying changes in methylation status of their promoter-associated CpG islands in DNMT3A mutant-transduced stem/progenitor cells. DNMT3A mutant also promotes monoblastic transformation in vitro in combination with HOXA9. Molecularly, DNMT3A mutant interacts with polycomb repressive complex 1 (PRC1), leading to transcriptional silencing of PU.1. Suppression of PRC1 impairs aberrant HSC accumulation and monoblastic transformation. Taken together, our results highlight the functional role of DNMT3A mutation, forming the basis for leukemia development.
Project description:Despite the impact of DNMT3A mutation in acute myeloid leukemia has been emphasized, the precise molecular mechanisms in leukemogenesis are largely unknown. Here we show that, in murine transplantation experiments, recipients transplanted with DNMT3A mutant-transduced cells exhibit aberrant hematopoietic stem cell (HSC) accumulation. Differentiation-associated genes are down-regulated without accompanying changes in methylation status of their promoter-associated CpG islands in DNMT3A mutant-transduced stem/progenitor cells. DNMT3A mutant also promotes monoblastic transformation in vitro in combination with HOXA9. Molecularly, DNMT3A mutant interacts with polycomb repressive complex 1 (PRC1), leading to transcriptional silencing of PU.1. Suppression of PRC1 impairs aberrant HSC accumulation and monoblastic transformation. Taken together, our results highlight the functional role of DNMT3A mutation, forming the basis for leukemia development. GFP-labeled empty vector, DNMT3A wild-type (WT), R882H-transduced LSK cells derived from transplanted mice were utilized for compared the expression profiles (3 sorted empty vector-transduced LSK cells, 3 sorted DNMT3A WT-transduced LSK cells, and 3 sorted DNMT3A R882H-transduced LSK cells. Total RNA was extracted by TaKaRa NucleoSpin RNA XS according to the manufacturerâs protocol. Amplification and biotin labeling of fragmented cDNA was carried out from 3.67 ng of total RNA by using NuGen Ovation Pico WTA System V2 (NuGEN) and SureTag Complete DNA Labeling Kit (Agilent). Each 2 μg of cDNA were hybridized to the Agilent SurePrint G3 Mouse Gene Expression 8x60K (Agilent) using Gene Expression Hybridization Kit (Agilent). After scanning, the signal intensity for each feature was measured by Agilent Feature Extraction (Agilent).
Project description:Somatic DNMT3A R882 codon mutations drive the most common form of clonal haematopoiesis (CH) and are associated with increased acute myeloid leukaemia (AML) risk1,2. Preventing expansion of DNMT3A-R882-mutant haematopoietic stem/progenitor cells (HSPCs) may therefore avert progression to AML. To identify DNMT3A-R882-mutant-specific vulnerabilities, we conducted a genome-wide CRISPR screen on primary mouse Dnmt3aR882H/+ HSPCs. Amongst the 640 vulnerability genes identified, many were involved in mitochondrial metabolism and metabolic flux analysis confirmed enhanced oxidative phosphorylation usage in Dnmt3aR882H/+ vs Dnmt3a+/+ (WT) HSPCs. We selected citrate/malate transporter Slc25a1 and complex I component Ndufb11, for which pharmacological inhibitors are available, for downstream studies. In vivo administration of SLC25A1 inhibitor CTPI2 and complex I inhibitors IACS-010759 and metformin, suppressed post-transplantation clonal expansion of Dnmt3aR882H/+, but not WT, LT-HSCs. The effect of metformin was recapitulated using a primary human DNMT3A-R882 CH sample. Notably, analysis of 412,234 UK Biobank participants revealed that individuals taking metformin had markedly lower prevalence of DNMT3A-R882-mutant CH, after controlling for potential confounders including glycated haemoglobin, diabetes and body mass index. Collectively, our data propose that modulation of mitochondrial metabolism as a therapeutic strategy for prevention of DNMT3A-R882-mutant AML.
Project description:Cellular binary fate decisions require the progeny to silence genes associated with the alternative fate. The major subsets of alpha:beta T cells have been extensively studied as a model system for fate decisions. While the transcription factor RUNX3 is required for the initiation of Cd4 silencing in CD8 T cell progenitors, it is not required to maintain the silencing of Cd4 and other helper T lineage genes. The other runt domain containing protein, RUNX1, silences Cd4 in an earlier T cell progenitor, but this silencing is reversed whereas the gene silencing after RUNX3 expression is not reverse. Therefore, we hypothesized that RUNX3 and not RUNX1 recruits other factors that maintains the silencing of helper T lineage genes in CD8 T cells. To this end, we performed a proteomics screen of RUNX1 and RUNX3 to determine candidate silencing factors.