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
Project description:Comparisons of molecular phenotypes across primates provide unique information to understand human biology and evolution and single-cell RNA-seq CRISPR interference screens are a powerful approach to analyze them. Here, we generate and validate three human, three gorilla and two cynomolgus iPS cell lines that carry a dox-inducible KRAB-dCas9 construct in the AAVS1 locus. We show that despite variable expression levels of KRAB-dCas9 among lines, comparable downregulation of target genes and comparable phenotypic effects are observed in a single-cell RNA-seq CRISPR interference screen. Hence, we provide valuable resources for performing and further extending CRISPRi screens in human and non-human primates.
Project description:Comparisons of molecular phenotypes across primates provide unique information to understand human biology and evolution and single-cell RNA-seq CRISPR interference screens are a powerful approach to analyze them. Here, we generate and validate three human, three gorilla and two cynomolgus iPS cell lines that carry a dox-inducible KRAB-dCas9 construct in the AAVS1 locus. We show that despite variable expression levels of KRAB-dCas9 among lines, comparable downregulation of target genes and comparable phenotypic effects are observed in a single-cell RNA-seq CRISPR interference screen. Hence, we provide valuable resources for performing and further extending CRISPRi screens in human and non-human primates.
Project description:As a potent and accurate genome-editing tool, CRISPR-Cas9 has been widely used in biomedical research and evaluated as gene therapy in treating human diseases. Although distinct engineered Cas9s, dCas9s and additional endonucleases have been identified, as these bacterial enzymes do not naturally express in mammalian cells, whether and how bacterial Cas9 proteins are regulated by mammalian hosts remains poorly understood. Here, we identified Keap1 as an endogenous E3 ligase that targets Cas9/dCas9/Fanzor1 for ubiquitination and degradation. Cas9-“ETGE” mutants evading Keap1 recognition displayed enhanced gene editing ability in cells. dCas9-“ETGE” mutants displayed extended protein half-life on chromatin, leading to significantly improved CRISPa and CRISPRi efficacy. Cas9 binding to Keap1 also inactivate Keap1 function via competing with Keap1 substrates or binding partners, while engineered Cas9 mutants showed less perturbation. Thus, our study reveals a mammalian specific Cas9 regulation and provides new Cas9 designs not only with enhanced gene regulatory capacity but also with minimal effects on disrupting endogenous Keap1 signaling.
Project description:we performed lentiviral CRISPR interference (CRISPRi) by recruiting dCas9 fused with the KRAB domain to the CSMD1 enhancer (fam3) in the neuronal precursor cell line – Lund human mesencephalic (LUHMES). Given that the expression of CSMD1 was not detectable in LUHMES cells we differentiated these cells into neurons. Differentiated neurons with CRISPRi of CSMD1 enhancer showed significantly higher expression of CSMD1 than control.
Project description:Assess the on- and off-target effects of dox-inducible CRISPR/Cas9 and CRISPRi constructs in a human iPS cell line. Transcript quantification of 3 cell lines, each plus or minus doxycycline and with or without specific single guide RNAs (sgRNAs), with 2 biological replicates each.
Project description:CRISPR-Cas transcriptional tools have been widely applied for programmable regulation of complex biological networks. In comparison to eukaryotic systems, bacterial CRISPR activation (CRISPRa) has stringent target site requirements for effective gene activation. While genes may not always have an NGG protospacer adjacent motif (PAM) at the appropriate position, PAM-flexible dCas9 variants can expand the range of targetable sites. Here we systematically evaluate a panel of PAM-flexible dCas9 variants for their ability to activate bacterial genes. We observe that dxCas9-NG provides a high dynamic range of gene activation for sites with NGN PAMs while dSpRY permits modest activity across almost any PAM. Similar trends were observed for heterologous and endogenous promoters. For all variants tested, improved PAM-flexibility comes with the tradeoff that CRISPRi-mediated gene repression becomes less effective. Weaker CRISPR interference (CRISPRi) gene repression can be partially rescued by expressing multiple sgRNAs to target many sites in the gene of interest. Our work provides a framework to choose the most effective dCas9 variant for a given set of gene targets, which will further expand the utility of CRISPRa/i gene regulation in bacterial systems.
Project description:The spatiotemporal control of 3D chromatin structure is fundamental for gene regulation, yet it remains challenging to obtain high-resolution chromatin interacting profiles at cis-regulatory elements (CREs) by chromatin conformation capture (3C)-based methods. Here, we describe the redesigned dCas9-based CAPTURE method for multiplexed, high-throughput and high-resolution analysis of locus-specific chromatin interactions. Using C-terminally biotinylated dCas9, endogenous biotin ligase and pooled sgRNAs, the new system enables quantitative analysis of the spatial configuration of a few to hundreds of enhancers or promoters in a single experiment, enabling systematic comparisons across CREs within and between gene clusters. We reveal the hierarchical structure of super-enhancers (SEs) and distinct modes of SE-gene interactions. Multiplexed capture of temporal dynamics of promoter-centric interactions establishes the instructive function of enhancer-promoter looping in transcriptional regulation during lineage differentiation. These applications illustrate the ability of multiplexed CAPTURE for decoding the organizational principles of genome structure and function.