Project description:DNA methyltransferases DNMT3A- and DNMT3B-mediated de novo DNA methylation critically regulates epigenomic and transcriptomic patterning during development. The hotspot DNMT3A mutations at the site of Arg822 (R882) promote macro-oligomer formation, leading to aberrant DNA methylation that in turn contributes to pathogenesis of acute myeloid leukemia (AML). However, the molecular basis underlying the hotspot mutation-induced functional mis-regulation of DNMT3A remains unclear. Here, we report the crystal structure of DNMT3A methyltransferase (MTase) domain, revealing a molecular basis for its DNMT3B-distinct oligomerization behavior. Introducing DNMT3B-converting mutations to DNMT3A R882 mutants also led to structure determination of R882H- and R882C-mutated DNMT3A, which show enhanced intermolecular contacts than wild-type DNMT3A. Consistently, our in vitro and genomic DNA methylation analyses reveal that the DNMT3B-converting mutations eliminate the gain-of-function effect of the DNMT3A R882 mutations in cells. Together, this study provides mechanistic insights into DNMT3A R882 mutation-triggered aberrant oligomerization and DNA hypomethylation in AML, with important implications in cancer therapy.
Project description:DNA methyltransferases DNMT3A- and DNMT3B-mediated de novo DNA methylation critically regulates epigenomic and transcriptomic patterning during development. The hotspot DNMT3A mutations at the site of Arg822 (R882) promote macro-oligomer formation, leading to aberrant DNA methylation that in turn contributes to pathogenesis of acute myeloid leukemia (AML). However, the molecular basis underlying the hotspot mutation-induced functional mis-regulation of DNMT3A remains unclear. Here, we report the crystal structure of DNMT3A methyltransferase (MTase) domain, revealing a molecular basis for its DNMT3B-distinct oligomerization behavior. Introducing DNMT3B-converting mutations to DNMT3A R882 mutants also led to structure determination of R882H- and R882C-mutated DNMT3A, which show enhanced intermolecular contacts than wild-type DNMT3A. Consistently, our in vitro and genomic DNA methylation analyses reveal that the DNMT3B-converting mutations eliminate the gain-of-function effect of the DNMT3A R882 mutations in cells. Together, this study provides mechanistic insights into DNMT3A R882 mutation-triggered aberrant oligomerization and DNA hypomethylation in AML, with important implications in cancer therapy.
Project description:Although the majority of acute myeloid leukemia (AML) patients initially respond to chemotherapy, most of them subsequently relapse due to persistent, chemoresistant disease. However, the mechanistic basis by which AML cells persist during chemotherapy has not been fully delineated. Recurrent somatic mutations in the DNA methyltransferase 3A gene (DNMT3A), most frequently at arginine 882 (DNMT3Amut), are commonly observed in AML patients, and are also detected in elderly subjects with clonal hematopoiesis in the absence of leukemic transformation. DNMT3Amut AML patients have an inferior outcome when treated with standard dose daunorubicin-based induction chemotherapy, suggesting that DNMT3Amut AML cells can persist following chemotherapy and drive relapse. DNMT3Amut cells show impaired nucleosome eviction and chromatin remodeling in response to DNA damage in the setting of anthracycline exposure. This defect leads to an inability to sense and repair DNA damage, which results in the accumulation of single-stranded DNA breaks and increased mutagenesis. Our studies identify a critical role for DNMT3A R882 mutations in driving AML chemoresistance, and highlight the importance of chromatin remodeling in the response to cytotoxic chemotherapy.
Project description:Although the majority of acute myeloid leukemia (AML) patients initially respond to chemotherapy, most of them subsequently relapse due to persistent, chemoresistant disease. However, the mechanistic basis by which AML cells persist during chemotherapy has not been fully delineated. Recurrent somatic mutations in the DNA methyltransferase 3A gene (DNMT3A), most frequently at arginine 882 (DNMT3Amut), are commonly observed in AML patients, and are also detected in elderly subjects with clonal hematopoiesis in the absence of leukemic transformation. DNMT3Amut AML patients have an inferior outcome when treated with standard dose daunorubicin-based induction chemotherapy, suggesting that DNMT3Amut AML cells can persist following chemotherapy and drive relapse. DNMT3Amut cells show impaired nucleosome eviction and chromatin remodeling in response to DNA damage in the setting of anthracycline exposure. This defect leads to an inability to sense and repair DNA damage, which results in the accumulation of single-stranded DNA breaks and increased mutagenesis. Our studies identify a critical role for DNMT3A R882 mutations in driving AML chemoresistance, and highlight the importance of chromatin remodeling in the response to cytotoxic chemotherapy.
Project description:Although the majority of acute myeloid leukemia (AML) patients initially respond to chemotherapy, most of them subsequently relapse due to persistent, chemoresistant disease. However, the mechanistic basis by which AML cells persist during chemotherapy has not been fully delineated. Recurrent somatic mutations in the DNA methyltransferase 3A gene (DNMT3A), most frequently at arginine 882 (DNMT3Amut), are commonly observed in AML patients, and are also detected in elderly subjects with clonal hematopoiesis in the absence of leukemic transformation. DNMT3Amut AML patients have an inferior outcome when treated with standard dose daunorubicin-based induction chemotherapy, suggesting that DNMT3Amut AML cells can persist following chemotherapy and drive relapse. DNMT3Amut cells show impaired nucleosome eviction and chromatin remodeling in response to DNA damage in the setting of anthracycline exposure. This defect leads to an inability to sense and repair DNA damage, which results in the accumulation of single-stranded DNA breaks and increased mutagenesis. Our studies identify a critical role for DNMT3A R882 mutations in driving AML chemoresistance, and highlight the importance of chromatin remodeling in the response to cytotoxic chemotherapy.
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 ‘hotspot’ 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 ‘stemness’ 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.