Loss of Dnmt3a Immortalizes Hematopoietic Stem Cells in vivo [RNA-Seq]
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE98184 | GEO | 2018/04/25
REPOSITORIES: GEO
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Project description:Recent epidemiological studies have shown that cancer-associated DNMT3A mutations can be detected in the blood of a large proportion of asymptotic elderly individuals. It is important to understand how these mutations provide a competitive advantage to HSCs and allow them to establish clonal dominance. Here we demonstrate that the stress of serial HSC transplantation immortalizes Dnmt3a-null HSCs.
2018-04-25 | GSE98186 | GEO
Project description:Recent epidemiological studies have shown that cancer-associated DNMT3A mutations can be detected in the blood of a large proportion of asymptotic elderly individuals. It is important to understand how these mutations provide a competitive advantage to HSCs and allow them to establish clonal dominance. Here we demonstrate that the stress of serial HSC transplantation immortalizes Dnmt3a-null HSCs.
2018-04-25 | GSE98185 | GEO
Project description:Epigenetic modifying enzymes DNMT3A and TET2 are recurrently mutated in hematological disorders despite possessing opposing biochemical functions in the DNA methylation processes. Using conditional ablation, we show these contrasting genotypes result in different functional effects in hematopoietic stem cells (HSCs). Loss of Dnmt3a bestows enhanced self-renewal on HSCs in serial, competitive repopulation assays while Tet2 loss functionally depletes HSCs after a tertiary transplant despite an initial competitive advantage. Moreover, loss of Tet2 sensitizes HSCs to the addition of a common leukemic driver mutation Flt3-ITD. Tet2-null mice experience a 5-fold decrease in median survival time when combined with Flt3-ITD while that of Dnmt3a-null mice decreases 1.5-fold. Molecular characterization of transcriptomes and chromatin accessibility reflects the functional differences between the genotypes as Dnmt3a-null cells reside in a more stem cell-like state while Tet2 loss leads to functional attrition of down-stream progenitors. These data further prove that DNMT3A and TET2 mutations lead HSCs down different molecular and functional pathways despite similar disease destinations.
2020-04-01 | GSE139911 | GEO
Project description:Mutations in the epigenetic modifiers DNMT3A and TET2 non-randomly co-occur in lymphoma and leukemia despite their epistasis in the methylation-hydroxymethylation pathway. Using double knock-out (DKO) mice in which malignancy development is accelerated, we show that the DKO methylome reflects regions of independent, competitive and cooperative activity. Expression of lineage-specific transcription factors, including the erythroid regulator Klf1 is upregulated in DKO HSCs. DNMT3A and TET2 both repress Klf1 suggesting a model of cooperative inhibition by the epigenetic modifiers. These data demonstrate a dual role for TET2 in promoting and inhibiting HSC differentiation, loss of which, along with DNMT3A, obstructs differentiation leading to transformation.
2016-05-20 | GSE72148 | GEO
Project description:In the aging hematopoietic system, blood cell production becomes dominated by a limited number of hematopoietic stem cell (HSC) clones. While somatic mutations in the de novo DNA methyltransferase 3A (DNMT3A) frequently drive clone dominance, the aging milieu also likely contributes to selection of variant HSCs. The detrimental impact of clonal hematopoiesis on organismal health is thought to be mediated by differentiated progeny of variant HSCs through mechanisms as yet poorly understood. Here, we examined the interaction between high fat diet (HFD) as an inflammatory stressor and a hematopoietic system haploinsufficient for DNMT3A. Strikingly, HFD accelerated weight gain in mice harboring bone marrow with reduced DNMT3A. Moreover, distal tissues of such mice including pancreas, adipose, and spleen, harbored high levels of mutant macrophages that impacted tissue function. Aberrant DNA methylation and pro-inflammatory transcriptional activation in mutant-derived myeloid cells correlated with increased IL-6 and TNFa signaling. Together, these findings identify synergism between HFD and DNMT3A haploinsufficiency that, through increased inflammatory myeloid cell functions, can contribute to deterioration in organismal health.
2024-01-01 | GSE208075 | GEO
Project description:Accumulation of fatty bone marrow (FBM) is one of the key age related changes possibly influencing the blood system. While a link between obesity and cancer evolution has been reported it remains unknown whether FBM can modify the evolution of the early stages of leukemia and clonal hematopoiesis (CH). To address this question, we established different FBM mouse models in immunodeficient mice in whom we can study both mouse and human cells. We focused our studies on two FBM models: 1) after sublethal irradiation; 2) after castration; and in both we used an adipogenesis inhibitor as a control (PPARγ inhibitor). We transplanted both human and mice hematopoietic stem cells (HSCs) carrying DNMT3A mutations into immunodeficient mice with FBM. A significant increase in self-renewal was found when DNMT3AMut-HSCs were exposed to FBM. To better understand the mechanisms of the FBM-CH interaction, we performed single cell RNA-sequencing on HSPCs after FBM exposure in vivo. A 6-10 fold increase in DNMT3AMut-HSCs was observed under FBM conditions in comparison to normal bone marrow. Mutated HSCs from mice exposed to FBM exhibited an activated inflammatory signaling (IL-6 and IFNγ). Cytokine analysis of BM fluid and BM derived adipocytes grown in vitro demonstrated increased IL-6 levels under FBM conditions. Anti-IL-6 neutralizing antibodies significantly reduced the selective advantage of mice derived DNMT3AMut-HSCs exposed to FBM. Overall, paracrine FBM inflammatory signals promote DNMT3A-driven clonal hematopoiesis, which can be inhibited by blocking the IL-6 receptor.
2023-02-19 | E-MTAB-12614 | biostudies-arrayexpress
Project description:Accumulation of fatty bone marrow (FBM) is one of the key age related changes possibly influencing the blood system. While a link between obesity and cancer evolution has been reported it remains unknown whether FBM can modify the evolution of the early stages of leukemia and clonal hematopoiesis (CH). To address this question, we established different FBM mouse models in immunodeficient mice in whom we can study both mouse and human cells. We focused our studies on two FBM models: 1) after sublethal irradiation; 2) after castration; and in both we used an adipogenesis inhibitor as a control (PPARγ inhibitor). We transplanted both human and mice hematopoietic stem cells (HSCs) carrying DNMT3A mutations into immunodeficient mice with FBM. A significant increase in self-renewal was found when DNMT3AMut-HSCs were exposed to FBM. To better understand the mechanisms of the FBM-CH interaction, we performed single cell RNA-sequencing on HSPCs after FBM exposure in vivo. A 6-10 fold increase in DNMT3AMut-HSCs was observed under FBM conditions in comparison to normal bone marrow. Mutated HSCs from mice exposed to FBM exhibited an activated inflammatory signaling (IL-6 and IFNγ). Cytokine analysis of BM fluid and BM derived adipocytes grown in vitro demonstrated increased IL-6 levels under FBM conditions. Anti-IL-6 neutralizing antibodies significantly reduced the selective advantage of mice derived DNMT3AMut-HSCs exposed to FBM. Overall, paracrine FBM inflammatory signals promote DNMT3A-driven clonal hematopoiesis, which can be inhibited by blocking the IL-6 receptor.
2023-02-19 | E-MTAB-12613 | biostudies-arrayexpress
Project description:DNMT3A (which encodes a de novo DNA methyltransferase) is one of the most frequently mutated genes in AML genomes. Point mutations at position R882 have been shown to cause a dominant negative loss of DNMT3A methylation activity, but 15% of DNMT3A mutations are predicted to produce truncated proteins, which could either have dominant negative activities, or cause loss-of-function and haploinsufficiency. We demonstrate that three of these mutants produce truncated, inactive proteins that do not dimerize with wild-type DNMT3A, strongly supporting the haploinsufficiency hypothesis. We therefore evaluated hematopoiesis in mice heterozygous for a constitutive null Dnmt3a mutation: unmanipulated mice developed myeloid skewing over time, and their stem/progenitor cells exhibited a long-term competitive transplantation advantage. Dnmt3a+/- mice spontaneously developed transplantable myeloid malignancies after a long latent period, and three of 12 tumors tested had cooperating mutations in the Ras- MAPK pathway. The residual Dnmt3a allele was neither mutated nor downregulated in tumors. The bone marrow cells of Dnmt3a+/- mice had a subtle but significant DNA hypomethylation phenotype that was not associated with gene dysregulation. These data demonstrate that haploinsufficiency for DNMT3A alters hematopoiesis, and predisposes mice (and probably humans) to myeloid malignancies by a mechanism that is not yet clear.
2017-08-01 | GSE100702 | GEO
Project description:Age-associated clonal hematopoiesis (CH) occurs due to somatic mutations accrued in hematopoietic stem cells (HSCs) that confer a selective advantage in the context of aging. The mechanisms by which CH-mutant HSCs gain this advantage with aging are not comprehensively understood. Using unbiased transcriptomic approaches, we identify Oncostatin M (OSM) signaling as a candidate contributor to aging-driven Dnmt3a-mutant CH. We find that Dnmt3a-mutant HSCs from young mice do not functionally respond to acute OSM stimulation with respect to proliferation, apoptosis, hematopoietic engraftment, or myeloid differentiation. However, young Dnmt3a-mutant HSCs transcriptionally upregulate an inflammatory cytokine network in response to acute OSM including genes encoding IL-6, IL-1b and TNFa. In addition, OSM-stimulated Dnmt3a-mutant HSCs upregulate the anti-inflammatory genes Socs3 and Nr4a1, creating a negative feedback loop limiting sustained activation of the inflammatory network. In the context of an aged BM microenvironment with chronically elevated levels of OSM, Dnmt3a-mutant HSCs upregulate pro-inflammatory genes but do not upregulate Socs3 and Nr4a1. Together, our work suggests that chronic inflammation with aging exhausts the regulatory mechanisms in young CH-mutant HSCs that resolve inflammatory states, and that OSM is a master regulator of an inflammatory network that contributes to age-associated CH.
2024-02-18 | GSE236693 | GEO
Project description:DNMT3A encodes an enzyme that carries out de novo DNA methylation, which is essential for the acquisition of cellular identity and specialized functions during cellular differentiation. It is the most common driver gene of age-related clonal hematopoiesis. As such, mature immune cells harboring DNMT3A mutations can be readily detected in elderly individuals. Most acquired DNMT3A mutations are heterozygous and predicted to cause loss-of-function, indicating that haploinsufficiency is the predominant pathogenic mechanism. Yet, whether and how DNMT3A haploinsufficiency affects the function of mature immune cells is poorly understood. Here, we demonstrate that DNMT3A haploinsufficiency impairs the gain of DNA methylation at decommissioned enhancers, while simultaneously and unexpectedly impairs DNA demethylation at thousands of newly activated enhancers in mature human myeloid cells. The DNA methylation defects alter the activity of affected enhancers, leading to abnormal gene expression and impaired immune response. These findings provide insights into the mechanism of immune dysfunction associated with acquired DNMT3A mutations and clonal hematopoiesis.
2021-04-12 | GSE168811 | GEO