Structural Insights into DNMT3A-3L-Mediated de novo DNA Methylation on Chromatin
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PROVIDER: PRJNA1235252 | ENA |
REPOSITORIES: ENA
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Project description:DNA methylation is one of the critical epigenetic mechanisms, yet its establishment and regulation during mammalian embryonic development remain poorly understood. DNA methyltransferases DNMT3A and DNMT3B require catalytically inactive variants such as DNMT3L or DNMT3B3 to function effectively during gametogenesis and early embryogenesis. Abnormal DNA methylation can lead to genomic instability and oncogenesis, underscoring the importance of deciphering its molecular mechanisms, especially during embryonic development, where DNMT3L is primarily expressed. Here, we present a high-resolution cryo-EM structure of the nucleosome-bound full-length DNMT3A2-3L and oligomeric structures of the DNMT3A2-3L complex in its nucleosome-free state. Notably, in the nucleosome-bound complex, we observed a 180° rotational difference in the C-terminal “Switching Helix” of DNMT3L compared to its counterpart in DNMT3B3 within the DNMT3A2-3B3-NCP complex, eliminating the direct interactions with the nucleosome acidic patch. Instead, we identify a previously unrecognized mechanism in which the DNMT3L ADD domain significantly contributes to nucleosome engagement, while the DNMT3A PWWP domain inhibits nucleosome binding, suggesting an additional layer of regulatory complexity. Furthermore, our first-ever discovery of the novel oligomeric arrangement of DNMT3A2-3L in its nucleosome-free state highlights its dynamic assembly and indicates potential allosteric regulation. Based on the structures and supporting biophysical data, we propose that the DNMT3A-3L complex senses histone tail modifications and dynamically searches for and engages with linker DNA by selecting or reorganizing the complex to a more stable and active heterotetrameric state, shedding light on its role in co-regulating DNA methylation on chromatin.
2025-03-13 | GSE291793 | GEO
Project description:Structural basis for DNMT3A-mediated de novo DNA methylation
| PRJNA388375 | ENA
Project description:DNA methylation by de novo DNA methyltransferases 3A (DNMT3A) and 3B (DNMT3B) is essential for genome regulation and development. Dysregulation of this process is implicated in various diseases, notably cancer. However, the mechanisms underlying DNMT3 substrate recognition and enzymatic specificity remain elusive. Here we report a 2.65-Å crystal structure of the DNMT3A-DNMT3L-DNA complex where two DNMT3A monomers simultaneously attack two CpG dinucleotides, with the target sites separated by fourteen base pairs within the same DNA duplex. The DNMT3A-DNA interaction involves a target recognition domain (TRD), a catalytic loop and DNMT3A homodimeric interface. A TRD residue Arg836 makes crucial contact with CpG, ensuring DNMT3A enzymatic preference towards CpG sites in cells. Hematological cancer-associated somatic mutations at the substrate-binding sites decrease DNMT3A activity, induce CpG hypomethylation and promote transformation of hematopoietic cells. Together, our study reveals the mechanistic basis for DNMT3A-mediated DNA methylation and establishes its etiologic link to human disease.
2018-01-01 | GSE99391 | GEO
Project description:DNA methylation by de novo DNA methyltransferases 3A (DNMT3A) and 3B (DNMT3B) is essential for genome regulation and development. Dysregulation of this process is implicated in various diseases, notably cancer. However, the mechanisms underlying DNMT3 substrate recognition and enzymatic specificity remain elusive. Here we report a 2.65-Å crystal structure of the DNMT3A-DNMT3L-DNA complex where two DNMT3A monomers simultaneously attack two CpG dinucleotides, with the target sites separated by fourteen base pairs within the same DNA duplex. The DNMT3A-DNA interaction involves a target recognition domain (TRD), a catalytic loop and DNMT3A homodimeric interface. A TRD residue Arg836 makes crucial contact with CpG, ensuring DNMT3A enzymatic preference towards CpG sites in cells. Hematological cancer-associated somatic mutations at the substrate-binding sites decrease DNMT3A activity, induce CpG hypomethylation and promote transformation of hematopoietic cells. Together, our study reveals the mechanistic basis for DNMT3A-mediated DNA methylation and establishes its etiologic link to human disease.
2018-01-01 | GSE99390 | GEO
Project description:DNA methylation by de novo DNA methyltransferases 3A (DNMT3A) and 3B (DNMT3B) is essential for genome regulation and development. Dysregulation of this process is implicated in various diseases, notably cancer. However, the mechanisms underlying DNMT3 substrate recognition and enzymatic specificity remain elusive. Here we report a 2.65-Å crystal structure of the DNMT3A-DNMT3L-DNA complex where two DNMT3A monomers simultaneously attack two CpG dinucleotides, with the target sites separated by fourteen base pairs within the same DNA duplex. The DNMT3A-DNA interaction involves a target recognition domain (TRD), a catalytic loop and DNMT3A homodimeric interface. A TRD residue Arg836 makes crucial contact with CpG, ensuring DNMT3A enzymatic preference towards CpG sites in cells. Hematological cancer-associated somatic mutations at the substrate-binding sites decrease DNMT3A activity, induce CpG hypomethylation and promote transformation of hematopoietic cells. Together, our study reveals the mechanistic basis for DNMT3A-mediated DNA methylation and establishes its etiologic link to human disease.
2018-01-01 | GSE93727 | GEO
Project description:Mammalian DNA methylation patterns are established by two de novo DNA methyltransferases DNMT3A and DNMT3B, which exhibit both redundant and distinctive methylation activities. However, the related molecular basis remains undetermined. Through comprehensive structural, enzymology and cellular characterizations of DNMT3A and DNMT3B, here we uncovered distinct and interrelated modes-of-action underlying their CpG site and flanking sequence interaction. Strikingly, K777 of DNMT3B makes direct contacts with the DNA base at the +1 flank position of the cytosine methylation site, which contrasts with its counterpart in DNMT3A that forms base-specific contacts with the CpG site. Consequently, there is a divergent substrate and flanking sequence preference between DNMT3A and DNMT3B in vitro and in cells, thus providing an explanation for site-specific epigenomic alterations seen in ICF syndrome patients with DNMT3B mutations. Together, this study reveals crucial, yet complicated interplays of DNMT3s, DNA sequences and resultant methylation.
2020-06-18 | GSE145899 | GEO
Project description:Mammalian de novo DNA methyltransferases (DNMT) are responsible for the establishment of cell-type-specific DNA methylation in healthy and diseased tissues. Through genome-wide analysis of de novo methylation activity in murine stem cells we uncover that DNMT3A prefers to methylate CpGs followed by cytosines or thymines, while DNMT3B predominantly methylates CpGs followed by guanines or adenines. These signatures are further observed at non-CpG sites, resembling methylation context observed in specialised cell types, including neurons and oocytes. We further show that these preferences result from structural differences in the catalytic domains of the two de novo DNMTs and are not a consequence of differential recruitment to the genome. Molecular dynamics simulations suggest that, in case of human DNMT3A, the preference is due to favourable polar interactions between the flexible Arg836 side chain and the guanine that base-pairs with the cytosine following the CpG. By exchanging arginine to a lysine, the corresponding sidechain in DNMT3B, the sequence preference is reversed, confirming the requirement for arginine at this position. This context-dependent de novo DNA methylation by DNMT3A and DNMT3B, provides additional insights into the complex regulation of methylation patterns.
2020-11-16 | GSE151992 | GEO
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
2011-05-16 | E-GEOD-28629 | biostudies-arrayexpress
Project description:DNA methylation plays essential roles in mammalian development. During post-implantation development, de novo establishment of DNA methylation is accomplished by DNA methyltransferases, in particular DNMT3A and DNMT3B. At present, the distinct functions of these two enzymes remain largely elusive. To comprehensively identify the target sites for de novo DNA methylation by the DNMT3 enzymes, we took advantage of female mouse ES cells established in the presence of MEK and Gsk3 inhibitors, which lack most DNA methylation (2i/L ES cells), in combination with genetic ablation of Dnmt3a or Dnmt3b. We analyzed de novo DNA methylation in mouse embryonic fibroblasts (2i-MEFs) derived from Dnmt3 knockout (KO) 2i/L ES cells. Both Dnmt3a and Dnmt3b KO 2i-MEFs exhibited a modest but global reduction in CpG methylation, which was particularly notable on the X chromosome in Dnmt3b KO cells. Although most genes were methylated similarly in both knockouts, we identified 355 and 333 uniquely unmethylated genes in Dnmt3a and Dnmt3b KO 2i-MEFs, respectively. Notably, Dnmt3a was exclusively required for de novo methylation at both TSS regions and gene bodies of Polycomb group (PcG) target developmental genes. Consistent with this, tissue-specific DNA methylation at PcG target developmental genes was substantially reduced in Dnmt3a KO embryos. Finally, we found that human patients with DNMT3A mutant acute myeloid leukemia (AML) or harboring DNMT3B mutation associated with immunodeficiency, centromere, and facial anomalies (ICF) syndrome exhibited reduced CpG methylation at regions that were hypomethylated in Dnmt3a or Dnmt3b KO 2i-MEFs, respectively. Collectively, our findings in DNA-hypomethylated 2i/L ES cells revealed a set of unique de novo DNA methylation target sites for both DNMT3 enzymes during mammalian development that overlap with hypomethylated sites in human patients.
2020-05-13 | GSE111172 | GEO
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.
2011-05-16 | GSE28629 | GEO