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.
Project description:DNMT3A mutations are observed in myeloid malignancies, including myeloproliferative neoplasms (MPN), myelodysplastic syndromes (MDS), and acute myeloid leukemia (AML). Here we investigated the impact of conditional hematopoietic Dnmt3a loss on disease phenotype in primary mice. Dnmt3a ablation led to a lethal, fully penetrant myeloproliferative neoplasm with myelodysplasia (MDS/MPN) characterized by marked, progressive hepatomegaly that was transplantable. We detected expanded stem/progenitor populations in the liver of Dnmt3a-ablated mice. Homing studies showed that Dnmt3a-deleted bone marrow cells preferentially migrated to the liver. Hence, in addition to the established role of Dnmt3a in regulating self-renewal, Dnmt3a regulates tissue tropism and limits myeloid progenitor expansion in vivo.
Project description:DNMT3A mutations are observed in myeloid malignancies, including myeloproliferative neoplasms (MPN), myelodysplastic syndromes (MDS), and acute myeloid leukemia (AML). Here we investigated the impact of conditional hematopoietic Dnmt3a loss on disease phenotype in primary mice. Dnmt3a ablation led to a lethal, fully penetrant myeloproliferative neoplasm with myelodysplasia (MDS/MPN) characterized by marked, progressive hepatomegaly that was transplantable. We detected expanded stem/progenitor populations in the liver of Dnmt3a-ablated mice. Homing studies showed that Dnmt3a-deleted bone marrow cells preferentially migrated to the liver. Hence, in addition to the established role of Dnmt3a in regulating self-renewal, Dnmt3a regulates tissue tropism and limits myeloid progenitor expansion in vivo.
Project description:DNA Methyltransferase 3A (DNMT3A) is frequently mutated in various hematopoietic malignancies; however, the underlying oncogenic mechanisms remain elusive. Here, we report that DNMT3A mutational âhotspotâ at Arg882 (DNMT3A-R882H) cooperates with constitutively activated RAS in transforming murine hematopoietic stem/progenitor cells (HSPCs) ex vivo and inducing acute leukemias in vivo. DNMT3A-R882H potentiates aberrant transactivation of âstemnessâ gene expression programs, notably transcription factors Meis1, Hox-A, Mn1 and Mycn. Mechanistically, R882-mutated DNMT3A directly binds to cis-regulatory elements of these genes and induces focal CpG hypomethylation reminiscent of what was seen in human leukemias bearing DNMT3A R882 mutation. Furthermore, DNMT3A-R882H induced DNA hypomethylation facilitates gene enhancer/promoter activation and recruitment of Dot1l-associated transcription elongation machineries. Inactivation of Dot1l represses DNMT3AR882H-mediated stem cell gene dysregulation and acute leukemogenicity. In this dataset, we provided enhanced Reduced Representation Bisulfite Sequencing (eRRBS) DNA methylome profiling data showing effect of DNMT3A R882H mutation or WT expression on hematopoietic stem/progenitor cells with NRAS G12D co-transduction. eRRBBs DNA methylome analysis of Lin- enriched hematopoietic stem/progenitor cells with retroviral infection of NRAS G12D alone (EV-RAS), DNMT3A R882H with NRAS G12D (RH-RAS) or DNMT3A WT with NRAS G12D (WT-RAS) at day 16 post-transduction.
Project description:DNA Methyltransferase 3A (DNMT3A) is frequently mutated in various hematopoietic malignancies; however, the underlying oncogenic mechanisms remain elusive. Here, we report that DNMT3A mutational âhotspotâ at Arg882 (DNMT3A-R882H) cooperates with constitutively activated RAS in transforming murine hematopoietic stem/progenitor cells (HSPCs) ex vivo and inducing acute leukemias in vivo. DNMT3A-R882H potentiates aberrant transactivation of âstemnessâ gene expression programs, notably transcription factors Meis1, Hox-A, Mn1 and Mycn. Mechanistically, R882-mutated DNMT3A directly binds to cis-regulatory elements of these genes and induces focal CpG hypomethylation reminiscent of what was seen in human leukemias bearing DNMT3A R882 mutation. Furthermore, DNMT3A-R882H induced DNA hypomethylation facilitates gene enhancer/promoter activation and recruitment of Dot1l-associated transcription elongation machineries. Inactivation of Dot1l represses DNMT3AR882H-mediated stem cell gene dysregulation and acute leukemogenicity. In this dataset, we provided H3K4me1, H3K27ac and H3K79me2 ChIP-seq profiling data showing effect of DNMT3A R882H mutation or WT expression on epigenetic landscapes of hematopoietic stem/progenitor cells with NRAS G12D co-transduction. ChIP-seq analysis of Lin- enriched hematopoietic stem/progenitor cells with retroviral infection of NRAS G12D alone (EV-RAS), DNMT3A R882H with NRAS G12D (RH-RAS) or DNMT3A WT with NRAS G12D (WT-RAS) 3 weeks post-transduction. Antibodies of H3K4me1, H3K27ac and H3K79me2 were used.
Project description:Loss of chromosome 7 and del(7q) [-7/del(7q)] are recurring cytogenetic abnormalities in hematologic malignancies, including acute myeloid leukemia and therapy-related myeloid neoplasms, and associated with an adverse prognosis. We performed SNP array analysis on de novo and therapy-related myeloid neoplasms and identified a 2.17 Mb commonly deleted segment on chromosome band 7q22.1 containing CUX1, a gene encoding a homeodomain-containing transcription factor. Haploinsufficiency of the highly conserved ortholog, cut, led to hemocyte overgrowth and tumor formation in Drosophila melanogaster. Similarly, haploinsufficiency of CUX1 gave human hematopoietic cells a significant engraftment advantage upon transplantation into immunodeficient mice. These data identify CUX1 as a conserved, haploinsufficient tumor suppressor frequently deleted in myeloid neoplasms. We performed SNP-array analysis of 34 primary patient samples with de novo or therapy-related myeloid leukemia and one acute myeloid leukemia cell line, UoCM1. For patient samples, DNA was obtained from the white blood cells of bone marrow or peripheral blood leukemia specimens. Cytogenetic analysis revealed clonal -7/del(7q) in 17 of the cases.
Project description:Loss of chromosome 7 and del(7q) [-7/del(7q)] are recurring cytogenetic abnormalities in hematologic malignancies, including acute myeloid leukemia and therapy-related myeloid neoplasms, and associated with an adverse prognosis. We performed SNP array analysis on de novo and therapy-related myeloid neoplasms and identified a 2.17 Mb commonly deleted segment on chromosome band 7q22.1 containing CUX1, a gene encoding a homeodomain-containing transcription factor. Haploinsufficiency of the highly conserved ortholog, cut, led to hemocyte overgrowth and tumor formation in Drosophila melanogaster. Similarly, haploinsufficiency of CUX1 gave human hematopoietic cells a significant engraftment advantage upon transplantation into immunodeficient mice. These data identify CUX1 as a conserved, haploinsufficient tumor suppressor frequently deleted in myeloid neoplasms.
Project description:A transcriptome study in mouse hematopoietic stem cells was performed using a sensitive SAGE method, in an attempt to detect medium and low abundant transcripts expressed in these cells. Among a total of 31,380 unique transcript, 17,326 (55%) known genes were detected, 14,054 (45%) low-copy transcripts that have no matches to currently known genes. 3,899 (23%) were alternatively spliced transcripts of the known genes and 3,754 (22%) represent anti-sense transcripts from known genes.