Optimized RNA-targeting CRISPR/Cas13d technology outperforms shRNA in identifying functional circRNAs
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PROVIDER: PRJNA682745 | ENA |
REPOSITORIES: ENA
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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: Not available
| S-EPMC7818937 | biostudies-literature
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:Two shRNAs were placed into expression vectors harboring mir30 microRNA scaffold and an optimized scaffold where the artificial restriction sights in mir30 have been removed. After infection and selection shRNA processing was assessed by small-RNA cloning. For both shRNAs, placement into the optimized scaffold resulted in a ~two-fold increase in processing (based on smallRNA levels).
2014-11-24 | GSE62187 | GEO
Project description:Two shRNAs were placed into expression vectors harboring mir30 microRNA scaffold and an optimized scaffold where the artificial restriction sights in mir30 have been removed. After infection and selection shRNA processing was assessed by small-RNA cloning. For both shRNAs, placement into the optimized scaffold resulted in a ~two-fold increase in processing (based on smallRNA levels). Purpose: Others have reported that the EcoRI site that was introduced to the mir30 scaffold results in decreased smallRNA processing and hence reduced target knockdown. We've developed an alternative scaffold (termed ultramir) where this site is removed. smallRNA cloning was used to determine if the movement of this sight resulted in an increase in shRNA processing. Method: Two shRNAs (one targeting Renilla Luciferase and one targeting Human RPA3) were cloned into the original mir30 cassette the ultramir cassette. Each of the 4 constructs were infected in duplicate at single copy into cells and the cells seltected unitil infection percentages reached >90% (the shRenilla hairpin was infected into HEK293T cells and the shRPA3 construts into the Gallus gallus cell line ERC. After selection smallRNA cloning was perfromed and the amount of smallRNAs corrresponding to the two shRNAs compared to the endogenous microRNA populatlon. Results: smallRNA levels of the two shRNAs doubled relative to the microRNA population when they were placed into the ultramir scaffold.
2014-11-24 | E-GEOD-62187 | biostudies-arrayexpress
Project description:An optimized microRNA scaffold increases shRNA processing and target knockdown
| PRJNA263394 | ENA
Project description:To explore the overall circRNAs involved in growth and development of Arabidopsis thaliana across the lifespan, we deeply sequenced samples of whole plants from different developmental stages (cotyledons emergence, rosette leavesï¹¥1 mm, rosette growth complete, first flower open, flourishing florescence, first silique shattered, senescence). The total RNA was purified by rRNA-depletion and linear RNA removal with RNAseR, and sequenced by the Illumina HiSeq2500 platform. We obtained 31 Gb raw data and identified 1217 circRNAs with expression quantity. We annotated these circRNAs and predicted their targeted microRNA. The circRNAs involved in growth and development of Arabidopsis thaliana across lifespan were identified and analyzed using the Illumina HiSeq2500 platform.
2016-09-01 | E-GEOD-77672 | biostudies-arrayexpress
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:We conducted a two-vector CRISPR/Cas13d proliferation screening experiment. The screening library contains 10,830 sgRNAs targeting 192 protein-coding genes and 234 lncRNAs, and the screening experiment was performed using a melanoma cell line A375. It provides a unique dataset to model Cas13d sgRNA efficiency and specificity. We designed a deep learning model, named DeepCas13, to predict the sgRNA on-target activity with high accuracy from sgRNA sequences and RNA secondary structures.
2023-01-16 | GSE183256 | 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