Systematic identification and characterization of high efficiency Cas9 guide RNAs for therapeutic targeting of ADAR
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PROVIDER: PRJNA1179362 | ENA |
REPOSITORIES: ENA
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Project description:Therapeutic targeting of the adenosine deaminase ADAR has great potential in cancer and other indications; however, it remains unclear what approach can enable effective and selective therapeutic inhibition. Herein, we conduct multi-staged guide RNA screening and identify high efficiency Cas9 guide RNAs to enable a CRISPR/Cas-based approach for ADAR knockout. Through characterization in human primary immune cell systems we observe similar activity with two-part guide RNA and single guide RNA, dose responsive activity, similar guide activity rank order across different cell types, and favorable computational off-target profiles of candidate guide RNAs. We determine that knockout of ADAR using these guide RNAs induces pharmacodynamic responses primarily consisting of immunological responses such as a type I interferon response, consistent with the known function of ADAR as a key regulator of dsRNA sensing. We observe similar biological effects with targeting only the p150 isoform or both p110 and p150 isoforms of ADAR, indicating that at least in the contexts evaluated, loss of p150 ADAR mediates the primary response. These findings provide a resource of well-characterized, high efficiency ADAR-targeting Cas9 guide RNAs suitable for genomic medicines utilizing different delivery modalities and addressing different therapeutic areas.
2025-01-08 | GSE280530 | GEO
Project description:RNA base editing represents a promising alternative for genome editing. Recent approaches harness the endogenous RNA editing enzyme ADAR to circumvent problems related to the ectopic expression of an editing enzyme, but they suffer from sequence restriction, lack of efficiency, and bystander editing. Here, we present in‐silico optimized CLUSTER guide RNAs, which bind their target mRNAs in a multivalent fashion and thereby enable editing with unprecedented precision as shown by next generation sequencing. CLUSTER guide RNAs can be genetically encoded and manufactured into viruses to work in various cell lines. They achieve on‐target editing on endogenous transcripts like GUSB and NUP43 with yields up to 45% without bystander editing and have been shown to recruit endogenous ADAR in vivo. The CLUSTER approach tremendously enlarges the sequence space available for guide RNA design and opens new avenues for drug development in the field of RNA base editing.
2021-09-20 | GSE184244 | GEO
Project description:Understanding the impact of guide RNA (gRNA) and genomic locus on CRISPR/Cas9 activity is crucial to design effective gene editing assays. However, it is challenging to profile Cas9 activity in the endogenous cellular environment. We leverage our TRIP technology to integrate ~1k barcoded reporter genes in the genomes of mouse embryonic stem cells. We target the integrated reporters (IRs) using RNA-guided Cas9 and characterize induced mutations by sequencing. We report that gRNA-sequence and IR locus explain most variation in mutation efficiency. Predominant insertions of a gRNA-specific nucleotide are consistent with template-dependent repair of staggered DNA ends with 1-bp 5′ overhangs. We confirm that such staggered ends are induced by Cas9 in mouse pre-B cells. To explain observed insertions, we propose a model generating primarily blunt and occasionally staggered DNA ends. Mutation patterns indicate that gRNA-sequence controls the fraction of staggered ends, which could be used to optimize Cas9-based insertion efficiency.
2019-03-08 | GSE127752 | GEO
Project description:Endogenous double-stranded RNA is prevented from activating the cytosolic antiviral receptor MDA5 by adenosine-to-inosine editing by ADAR. Consequently, CRISPR/cas9 targeting ADAR in the human monocytic cell line THP-1 induces a spontaneous MDA5-dependent interferon response. This response is synergistically enhanced by concomitant CRISPR/cas9 targeting of hnRNPC. For this study, cas9 transgenic THP-1 were nucleofected with combinations of control gRNA, ADAR gRNA or hnRNPC gRNA to elucidate the basis for synergistic interferon-stmulated gene induction by combined ADAR and hnRNPC targeting. As a control for interferon-stimulated gene induction, IFN-alpha treated THP-1 were included, as well. To investigate potential interferon inducing mechanisms, we quantified gene expression, intron expression as well as the expression of regions rich in adenosine-to-inosine editing clusters. In a second part, nuclear vs cytosolic distribution of RNA rich in adenosine-to-inosine clusters was investigated by sequencing of total RNA or RNA from cytosolic and nuclear extracts of ADAR and/or hnRNPC targeted cells. In the first part of the study, STING-deficient, cas9 transgenic THP-1 were nucleofected with combinations of control, GFP-targeting, ADAR-targeting or hnRNPC-targeting gRNA and cells collected for total RNA extraction on days three, four and five after nucleofection. In addition, another control-nucleofected sample was treated on day 3 for 24 h. The experiment was repeated three times leading to three replicates per condition. In the second part, WT cas9-transgenic THP-1 were nucleofected with combinations of control, ADAR-targeting or hnRNPC-targeting gRNA and cells were either collected for total RNA extraction or separated into digitonin-soluble (cytosolic) and digitonin-resistant (nuclear and mitochondrial) compartments and then RNA extracted. The experiment was repeated twice leading to two replicates per condition. Differential gene expression analysis confirmed synergistic induction of interferon-stimulated genes. RNA-seq analysis demonstrated dysregulation of Alu-containing introns in hnRNPC-deficient cells via utilization of unmasked cryptic splice sites, including introns containing ADAR-dependent A-to-I editing clusters or regions enriched in editing clusters (ECRs) in general. These putative MDA5 ligands showed reduced editing in the absence of ADAR, providing a plausible mechanism for the combined effects of hnRNPC and ADAR. Part 2 of the study confirmed cytosolic access of a subset of ECRs to the cytosol.
2021-07-16 | GSE176012 | GEO
Project description:ADAR was deleted from the B16 murine melanoma line using CRISPR/Cas9. The loss-of-function phenotype was assessed in vitro with cytokine stimulation or vehicle control.
2018-12-30 | GSE110708 | GEO
Project description:To study target sequence specificity, selectivity, and reaction kinetics of Streptococcus pyogenes Cas9 activity, we challenged libraries of random variant targets with purified Cas9::guide RNA complexes in vitro. Cleavage kinetics were nonlinear, with a burst of initial activity followed by slower sustained cleavage. Consistent with other recent analyses of Cas9 sequence specificity, we observe considerable (albeit incomplete) impairment of cleavage for targets mutated in the PAM sequence or in "seed" sequences matching the proximal 8 bp of the guide. A second target region requiring close homology was located at the other end of the guide::target duplex (positions 13-18 relative to the PAM). Strikingly, a subset of variants which broke homology in the intervening region consistently increased the capacity of Cas9 to cleave in extended reactions. Sequences flanking the guide+PAM region had measurable (albeit modest) effects on cleavage. Taken together, these studies provide both a basis for predicting effective cleavage targets and a basis for potential optimization of guide RNAs to yield efficiency beyond that of the simple perfect-match guides.
2014-11-14 | GSE58426 | GEO
Project description:We report long-read sequencing results from the sox32 allele targeted with a multi-guide Cas9 RNP strategy. Embryos were cell-injected with Cas9 RNP programmed with 4 guides simultaneously targeting different portions of the sox32 gene. Genomic DNA was extracted from each embryo and the sox32 coding sequence and intron were amplified and sequenced. Six individual embryos were evaluated. We found that the majority of sequences were unique and most involved mutations confined to the target sites rather than larger lesions spanning two or more target sites. We also found that alleles accumulated mutations over several DNA replication cycles, which may in part explain the diversity of alleles that were generated. This study is the first to use high-throughput sequencing to evaluate of an allele of this size mutated by a multi-guide Cas9 RNP strategy and provides insights into the dynamics of CRISPR-Cas9 RNP gene editing in vivo.
2018-07-01 | GSE115233 | GEO
Project description:We engineered circular ADAR recruiting guide RNAs (cadRNAs) that efficiently recruit endogenous ADARs to edit specific sites on target RNA
2021-11-15 | GSE164956 | GEO
Project description:Guide-free Cas9 is detrimental to pig preimplantation embryo development
| PRJNA930390 | ENA
Project description:CRISPR interference (CRISPRi), the targeting of a catalytically dead Cas protein to block transcription, is the leading technique to silence gene expression in bacteria. However, design rules for CRISPRi remain poorly defined, limiting predictable design for gene interrogation, pathway manipulation, and high-throughput screens. Here we develop a best-in-class prediction algorithm for guide silencing efficiency by systematically investigating factors influencing guide depletion in multiple genome-wide essentiality screens, with the surprising discovery that gene-specific features such as transcriptional activity substantially impact prediction of guide activity. Accounting for these features as part of algorithm development allowed us to develop a mixed-effect random forest regression model that provides better estimates of guide efficiency than existing methods, as demonstrated in an independent saturating screen. We further applied methods from explainable AI to extract interpretable design rules from the model, such as sequence preferences in the vicinity of the PAM distinct from those previously described for genome engineering applications. Our approach provides a blueprint for the development of predictive models for CRISPR technologies where only indirect measurements of guide activity are available.
2023-12-19 | GSE196911 | GEO