Project description:To better characterize the effects of USP7 on DNA methylation, we performed reduced representative bisulfite sequencing (RRBS) analysis for a genome-wide comparison of DNA methylation in wild-type, USP7-KO-1, DNMT3A/3B-DKO and DNMT3A/DNMT3B/USP7-TKO HeLa cell lines. RRBS analysis showed increased DNA methylation in USK7-KO cells and loss of USP7 elevates DNA methylation on pre-existing sites and de novo methylation.
Project description:DNA methylation is a key epigenetic modification involved in regulating gene expression and maintaining genomic integrity. Somatic patterns of DNA methylation are largely static, apart from focal dynamics at gene regulatory elements. To further advance our understanding of the role of DNA methylation in human development and disease, we inactivated all three catalytically active DNA methyltransferases in human embryonic stem cells (ESCs) using CRISPR/Cas9 genome editing. Disruption of DNMT3A or DNMT3B individually, as well as of both enzymes in tandem, creates viable, pluripotent cell lines with distinct effects on their DNA methylation landscape as assessed by whole-genome bisulfite sequencing. Surprisingly, in contrast to mouse, deletion of DNMT1 resulted in rapid cell death in human ESCs. To overcome the immediate lethality, we generated a doxycycline (DOX) responsive tTA-DNMT1* rescue line and readily obtained homozygous DNMT1 mutant lines. However, DOX-mediated repression of the exogenous DNMT1* initiates rapid, global loss of DNA methylation, followed by extensive cell death, demonstrating that DNA methylation is essential for human ESCs cultured in standard conditions. In summary, our data provide a comprehensive characterization of DNMT mutant ESCs, including single base genome-wide maps of their targets. RRBS methylation profiling of DNMT3A/3B DKO human ES cells
Project description:Dicer initiates RNA interference by generating small RNAs involved in various silencing pathways. Dicer participates in centromeric silencing, but its role in the epigenetic regulation of other chromatin domains has not been explored. Here we show that Dicer1 deficiency in Mus musculus leads to decreased DNA methylation, concomitant with increased telomere recombination and telomere elongation. These DNA-methylation defects correlate with decreased expression of Dnmt1, Dnmt3a and Dnmt3b DNA methyltransferases (Dnmts), and methylation levels can be recovered by their overexpression. We identify the retinoblastoma-like 2 protein (Rbl2) as responsible for decreased Dnmt expression in Dicer1-null cells, suggesting the existence of Dicer-dependent small RNAs that target Rbl2. We identify the miR-290 cluster as being downregulated in Dicer1-deficient cells and show that it silences Rbl2, thereby controlling Dnmt expression. These results identify a pathway by which miR-290 directly regulates Rbl2-dependent Dnmt expression, indirectly affecting telomere-length homeostasis. Keywords: Cell type comparison
Project description:Cytosine methylation is an epigenetic mark that dictates cell fate and response to stimuli. The timing and establishment of methylation logic during kidney development remains unknown. DNA methyltransferase 3a and 3b are the enzymes capable of establishing de novo methylation. We generated mice with genetic deletion of Dnmt3a and Dnmt3b in nephron progenitor cells (Six2Cre Dnmt3a/3b) and kidney tubule cells (KspCre Dnmt3a/3b). We characterized KspCre Dnmt3a/3b mice at baseline and after injury. Unbiased omics profiling, such as whole genome bisulfite sequencing, reduced representation bisulfite sequencing and RNA sequencing were performed on whole-kidney samples and isolated renal tubule cells. KspCre Dnmt3a/3b mice showed no obvious morphologic and functional alterations at baseline. Knockout animals exhibited increased resistance to cisplatin-induced kidney injury, but not to folic acid–induced fibrosis. Whole-genome bisulfite sequencing indicated that Dnmt3a and Dnmt3b play an important role in methylation of gene regulatory regions that act as fetal-specific enhancers in the developing kidney but are decommissioned in the mature kidney. Loss of Dnmt3a and Dnmt3b resulted in failure to silence developmental genes. We also found that fetal-enhancer regions methylated by Dnmt3a and Dnmt3b were enriched for kidney disease genetic risk loci. Methylation patterns of kidneys from patients with CKD showed defects similar to those in mice with Dnmt3a and Dnmt3b deletion. Our results indicate a potential locus-specific convergence of genetic, epigenetic, and developmental elements in kidney disease development.
Project description:Dicer initiates RNA interference by generating small RNAs involved in various silencing pathways. Dicer participates in centromeric silencing, but its role in the epigenetic regulation of other chromatin domains has not been explored. Here we show that Dicer1 deficiency in Mus musculus leads to decreased DNA methylation, concomitant with increased telomere recombination and telomere elongation. These DNA-methylation defects correlate with decreased expression of Dnmt1, Dnmt3a and Dnmt3b DNA methyltransferases (Dnmts), and methylation levels can be recovered by their overexpression. We identify the retinoblastoma-like 2 protein (Rbl2) as responsible for decreased Dnmt expression in Dicer1-null cells, suggesting the existence of Dicer-dependent small RNAs that target Rbl2. We identify the miR-290 cluster as being downregulated in Dicer1-deficient cells and show that it silences Rbl2, thereby controlling Dnmt expression. These results identify a pathway by which miR-290 directly regulates Rbl2-dependent Dnmt expression, indirectly affecting telomere-length homeostasis. Experiment Overall Design: Two-condition experiments. 6 comparisons. One dye-swap technical replicate for all samples. 2-color platform.
Project description:The balance between pluripotency and differentiation is critical during development and regeneration. miR-203 is a microRNA previously involved in differentiation of different tissues as well as in tumor suppression in multiple malignancies. We have shown that miR-203 is able to promote differentiation of embryonic stem (ES) and induced pluripotent stem (iPS) cells without decreasing pluripotency. We have observed that transient expression of miR-203 significantly improves the efficiency of ES/iPS cells in the generation of quimeras and tetraploid complementation assays, in addition to inducing complex embryo-like structures when these pluripotent cells are injected in mice. Mechanistically, we have shown that miR-203 mediates such effects, at least in part, by modulating the levels of de novo DNA methyltransferases. In the present RNAseq we have transiently silenced the levels of DNMT3a/3b in order to compare their transcriptomic profile with that observed in PSCs transiently exponed to miR-203.
Project description:Maintenance of human pluripotent stem cells is dependent on extrinsic signals and cross talk between transcriptional and epigenetic regulators. Methylation of cytosines through the de novo methyltransferases DNMT3A and 3B plays an important role for exiting pluripotency and facilitating proper differentiation. Here, we generated and analyzed single cell expression data from wild-type and DNMT3A/B knockout human embryonic stem cells to better understand the precise effects on pluripotency and differentiation. Although DNA methylation is generally associated with gene silencing, we find unexpected and widespread transcriptional repression upon loss of DNMT3A or DNMT3A/3B. Furthermore, the transcriptional misregulation in DNMT3A knockout cells is largely propagated during differentiation towards mesoderm. Additionally, we observe increased cellular and transcriptional heterogeneity in undifferentiated cells upon deactivation of DNMTs as well as a notable change in cell cycle gene expression. Taken together, our single-cell RNA sequencing data provides several new insights into the role of DNA methylation in human pluripotent stem cells.
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.