Project description:Here, we show that Dnmt3a and Dnmt3b show non-overlapping and unique patterns of genomic localization in human epidermal stem cells and their differentiated counterparts. Dnmt3a, but not Dnmt3b, binds to the TSSs of a cohort of genes required for the interaction of stem cells with their underlying stroma. Unexpectedly, TSSs bound by Dnmt3a are highly transcribed and are devoid of DNA-methylation. Conversely, Dnmt3b specifically decorates the genebody of genes that establish the stem cell and differentiated signatures. Genic occupation by Dnmt3b correlates with high levels of DNA-methylation, broad domains of histone H3K4me3 8, and robust transcription. Intriguingly, both proteins also bind to the most active subset of enhancers, and are required for the production of their associated bidirectional enhancer RNAs 9. We show that typical and super-enhancers are very dynamically regulated during the linear transition of epidermal stem cells to differentiated keratinocytes. Interestingly, Dnmt3a and Dnmt3b show a strong preference for the super-enhancers that define the ectodermal lineage, but importantly, that also establish the functional traits associated to the stem cell and differentiated states. These enhancers contain very low levels of DNA-methylation, but high amounts of DNA-hydroxymethylation. Depletion of either protein completely impairs human epidermal stem cell self-renewal by inducing their spontaneous differentiation.
Project description:The de novo DNA methyltransferase Dnmt3a is mutated in human acute myeloid leukemia, and suppresses tumorigenesis in murine models of leukemia and lung cancer. Conversely, deregulation of the other de novo DNA methyltransferase, Dnmt3b, predominantly promotes tumorigenesis. However, the molecular mechanisms underlying the roles of Dnmt3a and Dnmt3b in cancer remain poorly understood. Using conditional knockout mice, here we show that Dnmt3a -- but not Dnmt3b -- strongly protects epidermal stem cells from carcinogen-induced tumor initiation, without affecting the progression of benign lesions to aggressive carcinomas. Only upon combined deletion of Dnmt3a and Dnmt3b, squamous cell carcinomas acquired a more aggressive fate and even became metastatic, indicating that Dnmt3b is tumor-suppressive, rather than pro-tumorigenic, in epidermal neoplasia. Mechanistically, Dnmt3a promotes the expression of epidermal differentiation genes by interacting with their enhancers, and inhibits the expression of lipid metabolism and cell proliferation genes by directly methylating their promoters. Altogether, we demonstrate that Dnmt3a, but not Dnmt3b, is critical for suppressing epidermal tumor initiation, while both enzymes prevent tumor progression.
Project description:The de novo DNA methyltransferase Dnmt3a is mutated in human acute myeloid leukemia, and suppresses tumorigenesis in murine models of leukemia and lung cancer. Conversely, deregulation of the other de novo DNA methyltransferase, Dnmt3b, predominantly promotes tumorigenesis. However, the molecular mechanisms underlying the roles of Dnmt3a and Dnmt3b in cancer remain poorly understood. Using conditional knockout mice, here we show that Dnmt3a -- but not Dnmt3b -- strongly protects epidermal stem cells from carcinogen-induced tumor initiation, without affecting the progression of benign lesions to aggressive carcinomas. Only upon combined deletion of Dnmt3a and Dnmt3b, squamous cell carcinomas acquired a more aggressive fate and even became metastatic, indicating that Dnmt3b is tumor-suppressive, rather than pro-tumorigenic, in epidermal neoplasia. Mechanistically, Dnmt3a promotes the expression of epidermal differentiation genes by interacting with their enhancers, and inhibits the expression of lipid metabolism and cell proliferation genes by directly methylating their promoters. Altogether, we demonstrate that Dnmt3a, but not Dnmt3b, is critical for suppressing epidermal tumor initiation, while both enzymes prevent tumor progression.
Project description:The de novo DNA methyltransferase Dnmt3a is mutated in human acute myeloid leukemia, and suppresses tumorigenesis in murine models of leukemia and lung cancer. Conversely, deregulation of the other de novo DNA methyltransferase, Dnmt3b, predominantly promotes tumorigenesis. However, the molecular mechanisms underlying the roles of Dnmt3a and Dnmt3b in cancer remain poorly understood. Using conditional knockout mice, here we show that Dnmt3a -- but not Dnmt3b -- strongly protects epidermal stem cells from carcinogen-induced tumor initiation, without affecting the progression of benign lesions to aggressive carcinomas. Only upon combined deletion of Dnmt3a and Dnmt3b, squamous cell carcinomas acquired a more aggressive fate and even became metastatic, indicating that Dnmt3b is tumor-suppressive, rather than pro-tumorigenic, in epidermal neoplasia. Mechanistically, Dnmt3a promotes the expression of epidermal differentiation genes by interacting with their enhancers, and inhibits the expression of lipid metabolism and cell proliferation genes by directly methylating their promoters. Altogether, we demonstrate that Dnmt3a, but not Dnmt3b, is critical for suppressing epidermal tumor initiation, while both enzymes prevent tumor progression.
Project description:We investigate the dynamics for Histone marks H3K4me3 and H3K27me3 during Dnmt3a and Dnmt3b knockout in mouse hematopoietic stem cells. The term dko represents double knockout of both Dnmt3a and Dnmt3b, while the term sko denotes single knockout of Dnmt3a. The Wildtype profiles were generated in study GSE47765. Mouse hematopoietic stem cell histone methylation profiles of sko and dko mice were generated generated by deep sequencing, in duplicate, using Illumina Hiseq 2000
Project description:DNA methylation is an epigenetic modification associated with transcriptional repression of promoters and is essential for mammalian development. Establishment of DNA methylation is mediated by the de novo DNA methyltransferases DNMT3A and DNMT3B, whereas DNMT1 ensures maintenance of methylation through replication. Absence of these enzymes is lethal, and somatic mutations in these genes have been associated with several human diseases. How genomic DNA methylation patterns are regulated remains poorly understood, as the mechanisms that guide recruitment and activity of DNMTs in vivo are largely unknown. To gain insights into this matter we determined chromosomal binding and site-specific activity of the mammalian de novo DNA methyltransferases DNMT3A and DNMT3B. We show that both enzymes localize to methylated, CpG dense regions in mouse stem cells, yet are excluded from active promoters and enhancers. By specifically measuring sites of de novo methylation, we observe that enzymatic activity reflects chromosomal binding. De novo methylation increases with CpG density, yet is excluded from nucleosomes. Notably, we observed selective binding of DNMT3B to the bodies of transcribed genes, which leads to their preferential methylation. This targeting to transcribed sequences requires SETD2-mediated methylation of lysine 36 on histone H3 and a functional PWWP domain of DNMT3B. Together these findings reveal how sequence and chromatin cues guide de novo methyltransferase activity to ensure methylome integrity. Genome-wide binding analysis for biotin-tagged DNMT3A2 and DNMT3B and variants in wild type ES, wild type neuroprogenitor cells, ES cells triple-KO for Dnmt1,3a,3b and ES cell mutant for Setd2
Project description:Induced pluripotent stem cells (iPSCs) are generated from somatic cells by the transduction of defined transcription factors and involves dynamic changes in DNA methylation. While the reprogramming of somatic cells is accompanied by de-methylation of pluripotency genes, the functional importance of de novo DNA methylation has not been clarified. Here, using loss-of-function studies, we generated iPSCs from fibroblasts that were deficient in de novo DNA methylation mediated by Dnmt3a and Dnmt3b. These iPSCs reactivated pluripotency genes, underwent self-renewal and showed restricted developmental potential which was rescued upon re-introduction of Dnmt3a and Dnmt3b. We conclude that de novo DNA methylation by Dnmt3a and Dnmt3b is dispensable for nuclear reprogramming of somatic cells. RNA levels of Dnmt3ab deficient iPSC cell lines were compared to control iPSC cell lines
Project description:We investigate the dynamics for Histone marks H3K4me3 and H3K27me3 during Dnmt3a and Dnmt3b knockout in mouse hematopoietic stem cells. The term dko represents double knockout of both Dnmt3a and Dnmt3b, while the term sko denotes single knockout of Dnmt3a. The Wildtype profiles were generated in study GSE47765.
Project description:This SuperSeries is composed of the SubSeries listed below. DNA methylation is an epigenetic modification associated with transcriptional repression of promoters and is essential for mammalian development. Establishment of DNA methylation is mediated by the de novo DNA methyltransferases DNMT3A and DNMT3B, whereas DNMT1 ensures maintenance of methylation through replication. Absence of these enzymes is lethal, and somatic mutations in these genes have been associated with several human diseases. How genomic DNA methylation patterns are regulated remains poorly understood, as the mechanisms that guide recruitment and activity of DNMTs in vivo are largely unknown. To gain insights into this matter we determined chromosomal binding and site-specific activity of the mammalian de novo DNA methyltransferases DNMT3A and DNMT3B. We show that both enzymes localize to methylated, CpG dense regions in mouse stem cells, yet are excluded from active promoters and enhancers. By specifically measuring sites of de novo methylation, we observe that enzymatic activity reflects chromosomal binding. De novo methylation increases with CpG density, yet is excluded from nucleosomes. Notably, we observed selective binding of DNMT3B to the bodies of transcribed genes, which leads to their preferential methylation. This targeting to transcribed sequences requires SETD2-mediated methylation of lysine 36 on histone H3 and a functional PWWP domain of DNMT3B. Together these findings reveal how sequence and chromatin cues guide de novo methyltransferase activity to ensure methylome integrity. Refer to individual Series
Project description:DNA methylation is an epigenetic modification associated with transcriptional repression of promoters and is essential for mammalian development. Establishment of DNA methylation is mediated by the de novo DNA methyltransferases DNMT3A and DNMT3B, whereas DNMT1 ensures maintenance of methylation through replication. Absence of these enzymes is lethal, and somatic mutations in these genes have been associated with several human diseases. How genomic DNA methylation patterns are regulated remains poorly understood, as the mechanisms that guide recruitment and activity of DNMTs in vivo are largely unknown. To gain insights into this matter we determined chromosomal binding and site-specific activity of the mammalian de novo DNA methyltransferases DNMT3A and DNMT3B. We show that both enzymes localize to methylated, CpG dense regions in mouse stem cells, yet are excluded from active promoters and enhancers. By specifically measuring sites of de novo methylation, we observe that enzymatic activity reflects chromosomal binding. De novo methylation increases with CpG density, yet is excluded from nucleosomes. Notably, we observed selective binding of DNMT3B to the bodies of transcribed genes, which leads to their preferential methylation. This targeting to transcribed sequences requires SETD2-mediated methylation of lysine 36 on histone H3 and a functional PWWP domain of DNMT3B. Together these findings reveal how sequence and chromatin cues guide de novo methyltransferase activity to ensure methylome integrity. Whole-genome bisulfite sequencing for Dnmt1,3a,3b-triple-KO ES cells expressing DNMT3A2 or DNMT3B1 and for Dnmt1,3a,3b,Setd2-KO ES cells expressing DNMT3B1