DNMT3A regulates murine megakaryocyte-biased hematopoietic stem cell fate decisions.

Hematopoietic stem cells (HSCs) are defined by their capacity to regenerate all main components of the peripheral blood, but individual HSCs exhibit a range of preferences for generating downstream cell types. Their propensities are thought to be epigenetically encoded, but few differential regulatory mechanisms have been identified. In this work, we explored the role of the DNA methyltransferase 3A (DNMT3A) in the megakaryocyte-biased HSC population, which is thought to reside at the top of the hematopoietic hierarchy.

Clonal dynamics and somatic evolution of haematopoiesis in mouse.

Haematopoietic stem cells maintain blood production throughout life. Although extensively characterized using the laboratory mouse, little is known about clonal selection and population dynamics of the haematopoietic stem cell pool during murine ageing. We isolated stem cells and progenitors from young and old mice, identifying 221,890 somatic mutations genome-wide in 1,845 single-cell-derived colonies.

Autophagic signaling promotes systems-wide remodeling in skeletal muscle upon oncometabolic stress by D2-HG.

Objectives: Cachexia is a metabolic disorder and comorbidity with cancer and heart failure. The syndrome impacts more than thirty million people worldwide, accounting for 20% of all cancer deaths. In acute myeloid leukemia, somatic mutations of the metabolic enzyme isocitrate dehydrogenase 1 and 2 cause the production of the oncometabolite D2-hydroxyglutarate (D2-HG).

TET2 modulates spatial relocalization of heterochromatin in aged hematopoietic stem and progenitor cells.

DNA methylation deregulation at partially methylated domains (PMDs) represents an epigenetic signature of aging and cancer, yet the underlying molecular basis and resulting biological consequences remain unresolved. We report herein a mechanistic link between disrupted DNA methylation at PMDs and the spatial relocalization of H3K9me3-marked heterochromatin in aged hematopoietic stem and progenitor cells (HSPCs) or those with impaired DNA methylation. We uncover that TET2 modulates the spatial redistribution of H3K9me3-marked heterochromatin to mediate the upregulation of endogenous retroviruses (ERVs) and interferon-stimulated genes (ISGs), hence contributing to functional decline of aged HSPCs.

DNMT3A-coordinated splicing governs the stem state switch towards differentiation in embryonic and haematopoietic stem cells.

Upon stimulation by extrinsic stimuli, stem cells initiate a programme that enables differentiation or self-renewal. Disruption of the stem state exit has catastrophic consequences for embryogenesis and can lead to cancer. While some elements of this stem state switch are known, major regulatory mechanisms remain unclear.

Constitutive loss of DNMT3A causes morbid obesity through misregulation of adipogenesis.

DNA Methyltransferase 3 A (DNMT3A) is an important facilitator of differentiation of both embryonic and hematopoietic stem cells. Heterozygous germline mutations in lead to Tatton-Brown-Rahman Syndrome (TBRS), characterized by obesity and excessive height. While DNMT3A is known to impact feeding behavior via the hypothalamus, here we investigated a role in adipocyte progenitors utilizing heterozygous knockout mice that recapitulate cardinal TBRS phenotypes.

Modeling IKZF1 lesions in B-ALL reveals distinct chemosensitivity patterns and potential therapeutic vulnerabilities.

IKAROS family zinc finger 1 (IKZF1) alterations represent a diverse group of genetic lesions that are associated with an increased risk of relapse in B-cell acute lymphoblastic leukemia. Due to the heterogeneity of concomitant lesions, it remains unclear how IKZF1 abnormalities directly affect cell function and therapy resistance, and whether their consideration as a prognostic indicator is valuable in improving outcome. CRISPR/Cas9 strategies were used to engineer multiple panels of isogeneic lymphoid leukemia cell lines with a spectrum of IKZF1 lesions to measure changes in chemosensitivity, gene expression, cell cycle, and in vivo engraftment that can be linked to loss of IKAROS protein.

Perturbed hematopoiesis in individuals with germline DNMT3A overgrowth Tatton-Brown-Rahman syndrome.

Tatton-Brown-Rahman syndrome (TBRS) is an overgrowth disorder caused by germline heterozygous mutations in the DNA methyltransferase DNMT3A. DNMT3A is a critical regulator of hematopoietic stem cell (HSC) differentiation and somatic DNMT3A mutations are frequent in hematologic malignancies and clonal hematopoiesis. Yet, the impact of constitutive DNMT3A mutation on hematopoiesis in TBRS is undefined.

Bcor deficiency perturbs erythro-megakaryopoiesis and cooperates with Dnmt3a loss in acute erythroid leukemia onset in mice.

Recurrent loss-of-function mutations of BCL6 co-repressor (BCOR) gene are found in about 4% of AML patients with normal karyotype and are associated with DNMT3a mutations and poor prognosis. Therefore, new anti-leukemia treatments and mouse models are needed for this combinatorial AML genotype. For this purpose, we first generated a Bcor knockout mouse model characterized by impaired erythroid development (macrocytosis and anemia) and enhanced thrombopoiesis, which are both features of myelodysplasia/myeloproliferative neoplasms.

Tissue-Biased Expansion of DNMT3A-Mutant Clones in a Mosaic Individual Is Associated with Conserved Epigenetic Erosion.

DNA methyltransferase 3A (DNMT3A) is the most commonly mutated gene in clonal hematopoiesis (CH). Somatic DNMT3A mutations arise in hematopoietic stem cells (HSCs) many years before malignancies develop, but difficulties in comparing their impact before malignancy with wild-type cells have limited the understanding of their contributions to transformation. To circumvent this limitation, we derived normal and DNMT3A mutant lymphoblastoid cell lines from a germline mosaic individual in whom these cells co-existed for nearly 6 decades.

Preparing the child welfare workforce: Organizational commitment, identity, and desire to stay.

Background: Since 1995, Colorado has had a Title IV-E child welfare Stipend Program, most recently involving four universities in partnership with the Colorado Department of Human Services.

Objective: A ten-year cohort study was conducted to understand program graduates' experiences with organizational commitment, the impact of stipends on child welfare professional identity and desire to remain in the child welfare field.

Participants And Methods: The mixed methods evaluation involved 245 stipend graduates from 2006 to 2016 from Bachelor of Social Work (BSW) and Master of Social Work (MSW) programs and included an online survey and focus groups.

A combination strategy targeting enhancer plasticity exerts synergistic lethality against BETi-resistant leukemia cells.

Primary and acquired drug resistance imposes a major threat to achieving optimized clinical outcomes during cancer treatment. Aberrant changes in epigenetic modifications are closely involved in drug resistance of tumor cells. Using BET inhibitor (BETi) resistant leukemia cells as a model system, we demonstrated herein that genome-wide enhancer remodeling played a pivotal role in driving therapeutic resistance via compensational re-expression of pro-survival genes.

Dnmt3a loss and Idh2 neomorphic mutations mutually potentiate malignant hematopoiesis.

Mutations in the epigenetic regulators DNMT3A and IDH1/2 co-occur in patients with acute myeloid leukemia and lymphoma. In this study, these 2 epigenetic mutations cooperated to induce leukemia. Leukemia-initiating cells from Dnmt3a-/- mice that express an IDH2 neomorphic mutant have a megakaryocyte-erythroid progenitor-like immunophenotype, activate a stem-cell-like gene signature, and repress differentiated progenitor genes.

Antibiotic treatment ameliorates Ten-eleven translocation 2 (TET2) loss-of-function associated hematological malignancies.

TET2 is among the most frequently mutated genes in hematological malignancies, as well as in healthy individuals with clonal hematopoiesis. Inflammatory stress is known to promote the expansion of Tet2-deficient hematopoietic stem cells, as well as the initiation of pre-leukemic conditions. Infection is one of the most frequent complications in hematological malignancies and antibiotics are commonly used to suppress infection-induced inflammation, but their application in TET2 mutation-associated cancers remained underexplored.

Mutant NPM1 Maintains the Leukemic State through HOX Expression.

NPM1 is the most frequently mutated gene in cytogenetically normal acute myeloid leukemia (AML). In AML cells, NPM1 mutations result in abnormal cytoplasmic localization of the mutant protein (NPM1c); however, it is unknown whether NPM1c is required to maintain the leukemic state. Here, we show that loss of NPM1c from the cytoplasm, either through nuclear relocalization or targeted degradation, results in immediate downregulation of homeobox (HOX) genes followed by differentiation.

DNMT3A and TET1 cooperate to regulate promoter epigenetic landscapes in mouse embryonic stem cells.

Background: DNA methylation is a heritable epigenetic mark, enabling stable but reversible gene repression. In mammalian cells, DNA methyltransferases (DNMTs) are responsible for modifying cytosine to 5-methylcytosine (5mC), which can be further oxidized by the TET dioxygenases to ultimately cause DNA demethylation. However, the genome-wide cooperation and functions of these two families of proteins, especially at large under-methylated regions, called canyons, remain largely unknown.

Loss of Dnmt3a Immortalizes Hematopoietic Stem Cells In Vivo.

Somatic mutations in DNMT3A are recurrent events across a range of blood cancers. Dnmt3a loss of function in hematopoietic stem cells (HSCs) skews divisions toward self-renewal at the expense of differentiation. Moreover, DNMT3A mutations can be detected in the blood of aging individuals, indicating that mutant cells outcompete normal HSCs over time.

Genome-Wide Analysis of DNA Methylation in Hematopoietic Cells: DNA Methylation Analysis by WGBS.

DNA methylation is a major epigenetic modification that regulates gene expression, genome imprinting, and development and has a role in diseases including cancer. There are various methods for whole-genome methylation profiling that differ in cost and resolution. Recent advances in high-throughput sequencing technologies coupled with bisulfite treatment enable absolute DNA methylation quantification and genome-wide single-nucleotide resolution analysis.

DNMT3A and TET2 compete and cooperate to repress lineage-specific transcription factors in hematopoietic stem cells.

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 Dnmt3a and Tet2 double-knockout mice in which the development of malignancy is accelerated, we show that the double-knockout methylome reflects regions of independent, competitive and cooperative activity. Expression of lineage-specific transcription factors, including the erythroid regulators Klf1 and Epor, is upregulated in double-knockout hematopoietic stem cells (HSCs).