Assessment of on- and off-target effects of dSpCas9-DNMT3A and dSpCas9-TET1 fusion proteins and the impact of modulating promoter strength on the specificity of CRISPR/dCas9-based epigenetic editing tools
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PROVIDER: PRJNA522270 | ENA |
REPOSITORIES: ENA
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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.
2019-09-12 | GSE126528 | GEO
Project description:In order to assess Tet1 binding, we first generated a Flag tagged Tet1 ES cells and then knocked out Dnmt3a in the [WT, Tet1-Flag] cells. By Tet1 ChIP and Flag ChIP, we showed that Tet1 binding was complementary to Dnmt3a. And Tet1 binding was not affected or slightly increased at majority of its targets.
2018-05-16 | GSE100955 | GEO
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.
2018-06-05 | GSE107607 | GEO
Project description:We report the generation of CRISPR-dCas9 DNA methyltransferases to mediate targeted DNA methylation. Using the dCas9-BFP-DNMT3A and dCas9-BFP-DNMT3B methyltransferases, we have demonstrated that these two methyltransferase can mediate targeted methylation in three human genes tested: uPA, TGFBR3, and CDKN2A in human HEK293T cells. We also showed that these methyltransferases could mediate gene inhibition. five samples co-transfected with five uPA sgRNAs and each of the four dCas9 fusions, or control transfection with pUC19 plasmid
2016-06-01 | E-GEOD-74935 | biostudies-arrayexpress
Project description:Precise regulation of DNA methylation in mammals is critical for genome stability and epigenetic regulation. The discovery of the ten-eleven translocation (TET) proteins catalyzing the oxidation from 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC) revolutionized the perspective on the complexity and regulation of DNA modifications. Despite accumulating knowledge about the role of TET1, it remains unclear to what extent these can be attributed to its catalytic activity. Here, we use genome engineering and quantitative multi-omics approaches to dissect the role and mechanism of TET1 in mESCs. Our study identifies TET1 as an essential interaction hub for multiple chromatin modifying complexes and as a global regulator of histone modifications. Strikingly, we find that the majority of transcriptional regulation depends on non-catalytic functions of TET1. Moreover, we show that the establishment of H3K9me3 and H4K20me3 at ERV1, ERVK, and ERVL is mediated by TET1 independent of DNA demethylation. We provide evidence that repression of endogenous retroviruses depends on the interaction between TET1 and SIN3A. In summary, we demonstrate that the non-catalytic functions of TET1 are critical for regulation of gene expression and the silencing of endogenous retroviruses in mESCs.
2022-08-31 | PXD028850 | Pride
Project description:TET1 maintains hypomethylation at bivalent promoters through its catalytic activity in embryonic stem cells (ESCs). However, whether and how TET1 exerts catalytic activity-independent functions in regulating bivalent genes is not well understood. Therefore, we mapped the TET1 interactome in mouse ESCs using a SILAC IP-MS proteomics approach.
2022-06-10 | PXD033587 | Pride
Project description:A modular dCas9-SunTag DNMT3A epigenome editing system overcomes pervasive off-target activity of direct fusion dCas9-DNMT3A constructs
| PRJNA420755 | ENA
Project description:Mammalian DNA methylation is a critical epigenetic mechanism orchestrating gene expression networks in many biological processes. However, investigation of the functions of specific methylation events remains challenging. Here, we demonstrate that fusion of Tet1 or Dnmt3a with a catalytically inactive Cas9 (dCas9) enables targeted DNA methylation editing. Targeting of the dCas9-Tet1 or -Dnmt3a fusion protein to methylated or unmethylated promoter sequences caused activation or silencing, respectively, of an endogenous reporter. Targeted demethylation of the BDNF promoter IV or the MyoD distal enhancer by dCas9-Tet1 induced BDNF expression in post-mitotic neurons or activated MyoD facilitating reprogramming of fibroblasts into myoblasts, respectively. Targeted de novo methylation of a CTCF loop anchor site by dCas9-Dnmt3a blocked CTCF binding and interfered with DNA looping, causing altered gene expression in the neighboring loop. Finally, we show that these tools can edit DNA methylation in mice demonstrating their wide utility for functional studies of epigenetic regulation.
2016-09-23 | GSE83890 | GEO
Project description:Detection of DNA methylation in the genome has been possible for decades; however, the ability to deliberately and specifically manipulate local DNA methylation states in the genome has been extremely limited. Consequently, this has impeded our understanding of the direct effect 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. Recent adaptations of genome editing technologies, including fusion of the DNMT3A DNA methyltransferase catalytic domain to catalytically inactive Cas9 (dC9-D3A), have aimed to alter DNA methylation at desired loci. Here, we show that these tools exhibit consistent off-target DNA methylation deposition in the genome, limiting their capabilities to unambiguously assess the functional consequences of DNA methylation. To address this, 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 methylation by dC9-D3A. Furthermore, we used dC9Sun-D3A to demonstrate the binding sensitivity to DNA methylation for CTCF and NRF1 in situ. Overall, this modular dC9Sun-D3A system enables precise DNA methylation deposition with the lowest off-target DNA methylation levels reported to date, allowing accurate functional determination of the role of DNA methylation at single loci.
| S-EPMC6071642 | biostudies-literature
Project description:Surveillance of DNA methylation in mammals is critical for genome stability and epigenetic regulation. The discovery of the ten-eleven translocation (TET) proteins catalyzing the oxidation from 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC) revolutionized the understanding of DNA methylation dynamics. Interestingly, in recent years evidence accumulated that TET1 also harbours non-catalytic functions. However, the role and mechanism of TET1 DNA demethylation independent functions still remain poorly understood. Here, we use genome engineering and quantitative multi-omics approaches to dissect the non-catalytic role of TET1. Strikingly, we find that the majority of transcriptional regulation depends on non-catalytic functions of TET1. To gain insights into possible mechanisms by which TET1 regulates transcription independent of DNA demethylation, we asked if the loss of TET1 is accompanied by changes in the histone modificaiton landscape. To this end, we compared the relative abundances of core histone modifications between Tet1 KO, Tet1 CM and WT mESCs using quantitative LC-MS/MS analysis. Surprisingly, we observed a profound global reduction of pH4Kac and H4K20me3 as well as H3K27me3 in Tet1 KO mESC. Vice versa, the monomethylation states of the latter two residues, H3K27me1 and H4K20me1 were significantly increased in Tet1 KO. Similar to the results from the transcriptome data, most of these changes were specific to Tet1 KO cells.
2022-08-11 | PXD028566 | Pride