Project description:To investigate the genome-wide occupancy of the DNA methylation editing tool dCas9-DNMT3A in cells harboring non-targeting sgRNAs (CTRL) and cells harboring sgRNAs targeting the IL1RN promoter (sgIL1RN).
Project description:We assessed both on-target and off-target DNA methylation editing events following targeting with dCas9-DNMT3A to the IL1RN locus in cells undergoing B to macrophage transdifferentiation.
Project description:DNA methylation is a covalent modification of the genome that plays important roles in genome regulation and vertebrate development. Although detection of this modification in the genome has been possible for several decades, the ability to deliberately and specifically manipulate local DNA methylation states in the genome has been extremely limited. Consequently, this has impeded the direct determination of the consequence of DNA methylation on transcriptional regulation and transcription factor binding in the native chromatin context. Thus, highly specific targeted epigenome editing tools are needed to address this outstanding question. Recent adaptations of genome editing technologies, such as the fusion of the DNMT3A methyltransferase catalytic domain to catalytically inactive Cas9 (dC9-D3A), have aimed to provide new tools for altering DNA methylation at desired loci. Here, we performed a deeper analysis of the performance of the tools at a genome wide level which revealed consistent off-target binding events and DNA methylation deposition throughout the genome, limiting the capacity of these tools to generate unambiguous determination of the functional consequences of DNA methylation. To address this issue, we developed a modular dCas9-SunTag (dC9Sun-D3A) system that can recruit multiple DNMT3A catalytic domains to a target site for editing DNA-methylation. dC9Sun-D3A is tunable, specific and exhibits much higher induction of DNA methylation at target sites than the dC9-D3A direct fusion protein. Importantly, genome-wide characterization of dC9Sun-D3A binding sites and DNA methylation revealed minimal off-target protein binding and induction of DNA methylation with dC9Sun-D3A, compared to pervasive off-target binding and methylation by the dC9-D3A direct fusion construct. Furthermore, we used dC9Sun-D3A to test the impact of DNA methylation upon the DNA binding of CTCF and NRF1 upon targeted methylation of their core binding sites, demonstrating the binding sensitivity of these proteins to DNA methylation in situ. Overall, this modular dC9Sun-D3A system enables precise DNA methylation deposition with the least amount of off-target DNA methylation reported to date, allowing accurate functional determination of the role of DNA methylation at single loci.
Project description:We characterized the role of the DNA methyltransferase DNMT3A in the fate decisions of murine megakaryocyte-biased HSCs and in the differentiation of megakaryocytes and platelets. In this experiment, we isolated washed platelets from 4 WT and 4 Dnmt3a+/– germline mice (2 males and 2 females per group) and subjected them to proteomic analysis by mass-spectrometry. We sought to identify changes at the protein level that occur in platelets due to aberrant DNA methylation during the differentiation of upstream hematopoietic cells.
Project description:Inferring causal relationship between epigenetic marks and gene expression requires molecular tools which can precisely modify specific genomic regions in a living cell. In this work, we present a comprehensive, modular and extensible CRISPR/dCas9-based molecular toolbox for targeted epigenetic modulation and direct gene regulation. It features a system for expression of orthogonal dCas9 proteins fused to catalytic domains of various effectors, and includes a multi-gRNA system for targeting dCas9 orthologs to up to six loci. This part of the study aimed to determine the impact of promoter strength on modulating on- and off-target activity of dSpCas9-DNMT3A and dSpCas9-TET1 fusion proteins. The dSpCas9-DNMT3A N-terminal fusion was used to target IL6ST with four sgRNAs, and the dSpCas9-TET1 N-terminal fusion was used to target MGAT3 with five gRNAs. For each locus, two types of constructs were used: i) construct having both the fusion protein and the selection marker (PuroR) under the same strong, constitutive CAG promoter; ii) the fusion construct under the weak EFS promoter, while maintaining efficient selection of transfected cells with PuroR under the strong SV40 promoter. Epigenome-wide profiling was conducted using the Illumina Infinium Human MethylationEPIC Beadchip arrays to assess on- and off-target activity of the fusion proteins in transfected HEK293 cells.
Project description:We demonstrate that dCas9-SunTag-DNMT3A dramatically increased CpG methylation at the HOXA5 locus in human embryonic kidney 293T cells (HEK293T). Furthermore, using a single sgRNA, dCas9-SunTag-DNMT3A was able to methylate a 4.5 kb genomic region and repress HOXA5 gene expression. Reduced representation bisulfite sequencing (RRBS) and RNA-seq showed that dCas9-SunTag-DNMT3A methylated regions of interest with minimal impact on the global DNA methylome and transcriptome.
Project description:We demonstrate that dCas9-SunTag-DNMT3A dramatically increased CpG methylation at the HOXA5 locus in human embryonic kidney 293T cells (HEK293T). Furthermore, using a single sgRNA, dCas9-SunTag-DNMT3A was able to methylate a 4.5 kb genomic region and repress HOXA5 gene expression. Reduced representation bisulfite sequencing (RRBS) and RNA-seq showed that dCas9-SunTag-DNMT3A methylated regions of interest with minimal impact on the global DNA methylome and transcriptome.
Project description:We demonstrate that dCas9-SunTag-DNMT3A dramatically increased CpG methylation at the HOXA5 locus in human embryonic kidney 293T cells (HEK293T). Furthermore, using a single sgRNA, dCas9-SunTag-DNMT3A was able to methylate a 4.5 kb genomic region and repress HOXA5 gene expression. Reduced representation bisulfite sequencing (RRBS) and RNA-seq showed that dCas9-SunTag-DNMT3A methylated regions of interest with minimal impact on the global DNA methylome and transcriptome.
Project description:Here, we demonstrate that dCas9-SunTag-DNMT3A dramatically increased CpG methylation at the HOXA5 locus in human embryonic kidney 293T cells (HEK293T). Furthermore, using a single sgRNA, dCas9-SunTag-DNMT3A was able to methylate a 4.5 kb genomic region and repress HOXA5 gene expression. Reduced representation bisulfite sequencing (RRBS) and RNA-seq showed that dCas9-SunTag-DNMT3A methylated regions of interest with minimal impact on the global DNA methylome and transcriptome.