Project description:We investigated the role of DNMT1 in immune homeostasis by generating mice lacking DNMT1 in Foxp3+ T-regulatory (Treg) cells. These mice showed decreased peripheral Foxp3+ Tregs, complete loss of Foxp3+ Treg suppressive functions in vitro and in vivo, and died from autoimmunity by 3-4 weeks unless they received perinatal transfer of wild-type Tregs that prolonged their survival. Methylation of CpG-sites in the TSDR region of Foxp3 was unaffected by DNMT1 deletion, but microarray revealed more >500 proinflammatory and other genes were upregulated in DNMT1-/- Tregs. CD4-Cre-mediated DNMT1 deletion showed inability of conventional T cells to convert to Foxp3+ Treg under appropriate polarizing conditions. Hence, DNMT1 is absolutely necessary for maintenance of the gene program required for normal Treg development and function. RNA from three independent samples of magnetically separated CD4+CD25+ Treg of fl-DNMT1/Foxp3cre mice, compared to wild type (C57BL6) control
Project description:We investigated the role of DNMT1 in immune homeostasis by generating mice lacking DNMT1 in Foxp3+ T-regulatory (Treg) cells. These mice showed decreased peripheral Foxp3+ Tregs, complete loss of Foxp3+ Treg suppressive functions in vitro and in vivo, and died from autoimmunity by 3-4 weeks unless they received perinatal transfer of wild-type Tregs that prolonged their survival. Methylation of CpG-sites in the TSDR region of Foxp3 was unaffected by DNMT1 deletion, but microarray revealed more >500 proinflammatory and other genes were upregulated in DNMT1-/- Tregs. CD4-Cre-mediated DNMT1 deletion showed inability of conventional T cells to convert to Foxp3+ Treg under appropriate polarizing conditions. Hence, DNMT1 is absolutely necessary for maintenance of the gene program required for normal Treg development and function.
Project description:We report that Dnmt1 is crucial during perinatal intestinal development. Loss of Dnmt1 in intervillus progenitor cells causes global hypomethylation, DNA damage, premature differentiation, and apoptosis, and consequently, loss of nascent villi. We further confirm the critical role for Dnmt1 during crypt development using the in vitro organoid culture system, and illustrate a clear differential requirement for Dnmt1 in immature versus mature organoids. These results demonstrate an essential role for Dnmt1 in maintaining genomic stability during intestinal development and the establishment of intestinal crypts.
Project description:The DNA methyltransferase activity of DNMT1 is vital for genomic maintenance of DNA methylation. We report here that DNMT1 function is regulated by O-GlcNAcylation, a protein modification that is sensitive to glucose levels, and that elevated O-GlcNAcylation of DNMT1 from high glucose environment leads to alterations to the epigenome. Using mass spectrometry and complementary alanine mutation experiments, we identified S878 as the major residue that is O-GlcNAcylated on DNMT1. Functional studies further revealed that O-GlcNAcylation of DNMT1-S878 results in an inhibition of methyltransferase activity, resulting in a general loss of DNA methylation that is preferentially at partially methylated domains (PMDs). This loss of methylation corresponds with an increase in DNA damage and apoptosis. These results establish O-GlcNAcylation of DNMT1 as a mechanism through which the epigenome is regulated by glucose metabolism and implicates a role for glycosylation of DNMT1 in metabolic diseases characterized by hyperglycemia.
Project description:Lung endoderm development occurs through a series of finely coordinated transcriptional processes that are regulated by epigenetic mechanisms. However, the role of DNA methylation in regulating lung endoderm development remains poorly understood. We demonstrate that DNA methyltransferase 1 (Dnmt1) is required for early branching morphogenesis of the lungs and for restraining epithelial fate specification. Loss of Dnmt1 leads to an early branching defect, a loss of proximal endodermal cell differentiation, and an expansion of the distal endoderm compartment. Dnmt1 deficiency also leads to precocious distal endodermal cell differentiation with premature expression of alveolar type 2 cell restricted genes. These data reveal an important requirement for Dnmt1 mediated DNA methylation in early lung development to promote proper branching morphogenesis, maintain proximal endodermal cell fate, and suppress premature activation of the distal epithelial fate.
Project description:Regulatory T (Treg) cells play an indispensable role in immune homeostasis. The development and function of Tregs are dependent on transcriptional factor Foxp3, but how constant expression of Foxp3 is maintained in Tregs is not clear. Here we show that ablation of the conserved non-coding DNA sequence 2 (CNS2) at the Foxp3 locus in mice led to spontaneous lymphoproliferative disease and exacerbation of experimental autoimmune encephalomyelitis (EAE). CNS2 is required for activated Treg cells to maintain elevated Foxp3 expression, which is critical for their suppressor function and lineage stability. Mechanistically, upon TCR stimulation, NFAT binds to both CNS2 and Foxp3 promoter and mediates the interaction between CNS2 and Foxp3 promoter. Our findings demonstrated an essential role for CNS2 in maintaining the stability and function of activated Treg cells and identified NFAT as a key mediator of its function. Gene expression was profiled in T regulatory cells (Treg) in WT and CNS2 knockout mice. CNS2 knockout mice lack a conserved non-coding DNA sequence 2 (CNS2) at the Foxp3 locus. Treg cells were further sorted into Foxp3-high and Foxp3-low populations based on the expression level of Foxp3. mRNA was profiled using RNA-Seq (unstranded, polyA+, SE100) in replicate for each condition
Project description:The forkhead DNA-binding protein FOXP3 is critical for the development and suppressive function of CD4+CD25+ regulatory T cells (TREG), which play a key role in maintaining self tolerance. Functionally, FOXP3 is capable of repressing transcription of cytokine genes regulated by the Nuclear Factor of Activated T cells (NFAT). Various mechanisms have been proposed by which FOXP3 mediates these effects. Using novel HEK cell lines that inducibly express either wild-type (WT) or mutant FOXP3, we have identified genome-wide expression patterns showing among other features that NFAT2 as an early target of FOXP3-mediated transcriptional repression. Six biological replicates of wild-type induced FOXP3 cell lines and six biological replicates of mutated FOXP3 cell line were studied.
Project description:The RING E3 ubiquitin ligase UHRF1 controls DNA methylation through its ability to target the maintenance DNA methyltransferase DNMT1 to newly replicated chromatin. DNMT1 recruitment relies on ubiquitylation of histone H3 by UHRF1, however, how UHRF1 deposits ubiquitin onto the histone is unknown. Here, we demonstrate that the ubiquitin-like domain (UBL) of UHRF1 is essential for RINGmediated H3 ubiquitylation. Using chemical crosslinking and mass spectrometry, biochemical assays and recombinant chromatin substrates we show that the UBL participates in structural rearrangements of UHRF1 upon binding to chromatin and the E2 ubiquitin conjugating enzyme UbcH5a/UBE2D1. Similar to ubiquitin, the UBL exerts its effects through a hydrophobic patch that contacts a regulatory surface on the “backside” of the E2 to stabilise the E2-E3-chromatin complex. Our analysis of the enzymatic mechanism of UHRF1 uncovers an unexpected function of the UBLdomain and defines a new role for this domain in DNMT1-dependent inheritance of DNA methylation.
Project description:Orofacial clefts of the lip and palate are widely recognized to result from complex gene–environment interactions, but inadequate understanding of environmental risk factors has stymied development of prevention strategies. We interrogated the role of DNA methylation, an environmentally malleable epigenetic mechanism, in orofacial development. Expression of the key DNA methyltransferase enzyme DNMT1 was detected throughout palate morphogenesis in the epithelium and underlying cranial neural crest cell (cNCC) mesenchyme, a highly proliferative multipotent stem cell population that forms orofacial connective tissue. Genetic and pharmacologic manipulations of DNMT activity were then applied to define the tissue- and timing-dependent requirement of DNA methylation in orofacial development. cNCC-specific Dnmt1 inactivation targeting initial palate outgrowth resulted in OFCs, while later targeting during palatal shelf elevation and elongation did not. Conditional Dnmt1 deletion reduced cNCC proliferation and subsequent differentiation trajectory, resulting in attenuated outgrowth of the palatal shelves and altered development of cNCC-derived skeletal elements. Finally, we found that the cellular mechanisms of cleft pathogenesis observed in vivo can be recapitulated by pharmacologically reducing DNA methylation in multipotent cNCCs cultured in vitro. These findings demonstrate that DNA methylation is a crucial epigenetic regulator of cNCC biology, define a critical period of development in which its disruption directly causes OFCs, and provide opportunities to identify environmental influences that contribute to OFC risk.