Modeling CRISPR-Cas13d on-target and off-target effects using machine learning approaches
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE183256 | GEO | 2023/01/16
REPOSITORIES: GEO
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Project description:We performed an experimental Cas13d-SARScov2 genome-wide screen to identify gRNAs that would allow Cas13d to degrade the viral RNA. We built mCherry reporter plasmids that express mCherry with a 3kb 3'UTR deriving from the SARScov2 genome. In total we designed 11 reporters covering the entire plus strand of the viral genome and 11 other reporters covering the entire minus strand. Each of the 22 mCherry reporter plasmids carries a U6 expression cassette containing a Cas13d gRNA that targets the 3'UTR of the mCherry reporter. Each reporter is represented by a pool of reporters each containing a different gRNA that targets mCherry 3'UTR for a total average of ~300 gRNA per 3'UTR. The entire pool of 22 reporters, each with a pool of ~300 different gRNAs constitutes a comprehensive set ~6,500 reporters (~ 6,500 different gRNAs) that allowed us to interrogate the entire SARScov2 plus and minus strand viral RNA for regions of vulnerability and targetability. In order to specifically interrogate Cas13d activity an remove the biases that would be introduced in the reporter expression by the presence of a large 3kb 3'UTR we used a case (presence of Cas13d) control (absence of Cas13d) design. Briefly, the ~6,500 reporters were lentiviral transduced in RKO cells, the cells were split in 2 populations, 1 population was transduced with Cas13d and the other serving as control did not. The population expressing Cas13d was FACS sorted in low mCherry (efficient gRNAs) and high mCherry (un-efficient gRNAs) in 2 biological replicates and the genomic DNA of these populations was extracted, gRNAs were PCR amplified and sequenced. For the population that did not express Cas13d, a low mCherry, one high mCherry and unsorted population were sequenced as control libraries.
2023-10-29 | E-MTAB-11111 | biostudies-arrayexpress
Project description:Circular RNAs (circRNAs) are widely expressed, but their functions remain largely unknown. To study circRNAs in a high-throughput manner, short hairpin RNA (shRNA) screens1 have recently been used to deplete circRNAs by targeting their unique back-splicing junction (BSJ) sites. Here, we report frequent discrepancies between shRNA-mediated circRNA knockdown efficiency and the corresponding biological effect, raising pressing concerns about the robustness of shRNA screening for circRNA functional characterization. To address this issue, we leveraged the CRISPR/Cas13d system2 for functional study of circRNAs by optimizing the strategy for designing single guide RNAs to deplete circRNAs. We then performed shRNA and CRISPR/Cas13d parallel screenings and demonstrated that shRNA-mediated circRNA screening yielded a high rate of false positive phenotypes. Furthermore, using a CRISPR/Cas13d screening library targeting over 2,500 human hepatocellular carcinomas (HCC) related circRNAs, we identified a group of circRNAs, whose inhibition increased the therapeutic efficacy of sorafenib, an approved HCC drug. Collectively, these data demonstrate that CRISPR/Cas13d system is an effective approach to study the function of circRNAs in a high-throughput manner.
2020-12-06 | GSE162720 | GEO
Project description:A major challenge in the application of the CRISPR-Cas13d system is to accurately predict its guide-dependent on-target and off-target effect. Here, we perform CRISPR-Cas13d proliferation screens and design a deep learning model, named DeepCas13, to predict the on-target activity from guide sequences and secondary structures. DeepCas13 outperforms existing methods to predict the efficiency of guides targeting both protein-coding and non-coding RNAs. Guides targeting non-essential genes display off-target viability effects, which are closely related to their on-target efficiencies. Choosing proper negative control guides during normalization mitigates the associated false positives in proliferation screens. We apply DeepCas13 to the guides targeting lncRNAs, and identify lncRNAs that affect cell viability and proliferation in multiple cell lines. The higher prediction accuracy of DeepCas13 over existing methods is extensively confirmed via a secondary CRISPR-Cas13d screen and quantitative RT-PCR experiments. DeepCas13 is freely accessible via http://deepcas13.weililab.org. Application of CRISPR-Cas13d is limited by the inability to predict on- and off-targets. Here the authors perform CRISPR-Cas13d proliferation screens followed by modeling of Cas13d on- and off-targets; they design a deep learning model, DeepCas13, to predict the on-target activity of a gRNA.
| S-EPMC9912244 | biostudies-literature
Project description:To examine the potential off-target effects by CRISPR/Cas13d-mediated CTSL knockdown in 293FT cells
2022-06-09 | GSE203052 | GEO
Project description:Cas13 is a unique family of CRISPR endonucleases exhibiting programmable binding and cleavage of RNAs and is a strong candidate for eukaryotic RNA knockdown in the laboratory and the clinic. However, sequence-specific binding of Cas13 to the target RNA unleashes non-specific bystander RNA cleavage, or collateral activity, which may confound knockdown experiments and raises concerns for therapeutic applications. Although conserved across orthologs and robust in cell-free and bacterial environments, the extent of collateral activity in mammalian cells remains disputed. Here, we investigate Cas13d collateral activity in the context of an RNA-targeting therapy for myotonic dystrophy type 1, a disease caused by a transcribed long CTG repeat expansion. We find that when targeting CUGn RNA in HeLa and other cell lines, Cas13d depletes endogenous and transgenic RNAs, interferes with critical cellular processes, and activates stress response and apoptosis pathways. We also observe collateral effects when targeting other repetitive and unique transgenic sequences, and we provide evidence for collateral activity when targeting highly expressed endogenous transcripts. To minimize collateral activity for repeat-targeting Cas13d therapeutics, we introduce gRNA excision for negative-autoregulatory optimization (GENO), a simple strategy that leverages crRNA processing to control Cas13d expression and is easily integrated into an AAV gene therapy. We argue that thorough assessment of collateral activity is necessary when applying Cas13d in mammalian cells and that implementation of GENO illustrates the advantages of compact and universally robust regulatory systems for Cas-based gene therapies.
2021-12-23 | GSE191329 | GEO
Project description:Huntington's disease (HD) is a fatal, dominantly inherited neurodegenerative disorder caused by a CAG trinucleotide expansion in exon 1 of the huntingtin (HTT) gene. Although the pathogenesis of HD remains complex, the CAG-expanded (CAGEX) HTT mRNA and protein ultimately causes disease through a toxic gain-of-function mechanism. As the reduction of pathogenic mutant HTT mRNA is beneficial as a treatment, we developed a mutant allele-sensitive CAGEX RNA-targeting CRISPR-Cas13d system (Cas13d/CAGEX) that eliminates toxic CAGEX RNA in HD patient-derived fibroblasts and iPSC-derived striatal neurons. We show that intrastriatal delivery of Cas13d/CAGEX via a single adeno-associated viral vector, serotype 9 (AAV9) mediates significant and selective reduction of mutant HTT mRNA and protein levels within the striatum of heterozygous zQ175 mice, an established mouse model of HD. Moreover, the reduction of mutant HTT mRNA renders a sustained partial reversal of HD phenotypes, including improved motor coordination, attenuated striatal atrophy, and reduction of mutant HTT protein aggregates. Importantly, phenotypic improvements were durable for at least 8 months without gross or behavioral adverse effects, and with minimal off-target interactions of Cas13d/CAGEX in the mouse transcriptome. Taken together, we demonstrate a proof-of-principle of an RNA-targeting CRISPR/Cas13d system as a therapeutic approach for HD, a strategy with broad implications for the treatment of other dominantly inherited neurodegenerative disorders.
2022-11-15 | GSE214108 | GEO
Project description:Huntington's disease (HD) is a fatal, dominantly inherited neurodegenerative disorder caused by a CAG trinucleotide expansion in exon 1 of the huntingtin (HTT) gene. Although the pathogenesis of HD remains complex, the CAG-expanded (CAGEX) HTT mRNA and protein ultimately causes disease through a toxic gain-of-function mechanism. As the reduction of pathogenic mutant HTT mRNA is beneficial as a treatment, we developed a mutant allele-sensitive CAGEX RNA-targeting CRISPR-Cas13d system (Cas13d/CAGEX) that eliminates toxic CAGEX RNA in HD patient-derived fibroblasts and iPSC-derived striatal neurons. We show that intrastriatal delivery of Cas13d/CAGEX via a single adeno-associated viral vector, serotype 9 (AAV9) mediates significant and selective reduction of mutant HTT mRNA and protein levels within the striatum of heterozygous zQ175 mice, an established mouse model of HD. Moreover, the reduction of mutant HTT mRNA renders a sustained partial reversal of HD phenotypes, including improved motor coordination, attenuated striatal atrophy, and reduction of mutant HTT protein aggregates. Importantly, phenotypic improvements were durable for at least 8 months without gross or behavioral adverse effects, and with minimal off-target interactions of Cas13d/CAGEX in the mouse transcriptome. Taken together, we demonstrate a proof-of-principle of an RNA-targeting CRISPR/Cas13d system as a therapeutic approach for HD, a strategy with broad implications for the treatment of other dominantly inherited neurodegenerative disorders.
2022-11-15 | GSE214109 | GEO
Project description:Early embryonic development is driven by maternal gene products deposited into the oocyte. Due to the lack of reliable knockdown strategies, maternal mRNA functions have remained elusive. CRISPR-Cas13 systems have recently been employed to induce RNA degradation in yeast, plants and mammalian cell lines. However, no systematic study of the potential of Cas13 has been carried out in an animal model system. Here, we show that CRISPR-Cas13d is an effective and precise system to deplete specific mRNA transcripts in zebrafish embryos. We demonstrate that both zygotically-expressed and maternally-provided transcripts are efficiently targeted, resulting in an 85% average decrease in transcript level and the recapitulation of well-known embryonic phenotypes. Moreover, we show that this system can be used in medaka, killifish, sea anemone and mouse embryos. All together our results demonstrate that CRISPR-Cas13d is an efficient knockdown platform to understand gene function in animal embryos.
2022-01-21 | GSE135884 | GEO
Project description:The intrinsic collateral cleavage activity of Cas13d,which refers to the gRNA-independent degradation of bystander RNA, significantly limits its therapeutic potential. To extensively evaluate the collateral effects of hpCas13d genome-wide, we conducted RNA-seq analysis of the transcriptome in HEK293T cells after the transfections with dCas13d, wtCas13d, hpCas13d, and hfCas13d . Compared to dCas13d, wtCas13d with a PPIA gRNA (reported to induce the significant collateral cleavage) resulted in significant downregulations of thousands genes. In sharp contrast, hpCas13d and hfCas13d showed much less off-target genes, respectively. These findings demonstrate that hpCas13d exhibits reduced collateral activity, rendering it suitable for in vivo applications.
2024-02-28 | GSE260500 | GEO
Project description:CRISPR technologies have begun to revolutionize T cell therapies; however, conventional CRISPR/Cas9 genome-editing tools are limited in their safety, efficacy, and scope. To address these challenges, we developed MEGA (Multiplexed Effector Guide Arrays), a platform for programmable and scalable regulation of the T cell transcriptome using the RNA-guided, RNA-targeting activity of CRISPR/Cas13d. MEGA enables quantitative, reversible, and massively-multiplexed gene knockdown in primary human T cells without targeting or cutting genomic DNA. Applying MEGA to a model of CAR T cell exhaustion, we robustly suppressed inhibitory receptor upregulation and uncovered paired regulators of T cell function through combinatorial CRISPR screening. We additionally implemented druggable regulation of MEGA to control CAR activation in a receptor-independent manner. Lastly, MEGA enabled multiplexed disruption of immunoregulatory metabolic pathways to enhance CAR T cell fitness and anti-tumor activity in vitro and in vivo. MEGA offers a versatile synthetic toolkit for applications in cancer immunotherapy and beyond.
2023-11-06 | GSE246823 | GEO