Optimized CRISPR guide RNA library cloning reduces skew and enables more compact genetic screens
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PROVIDER: PRJNA922472 | ENA |
REPOSITORIES: ENA
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Project description:The development of CRISPR genetic screening tools has improved functional genomics, as these tools enable precise genomic editing, provide broad access to genomic regions beyond protein-coding genes, and have fewer off-target effects than other functional genomics modalities, allowing for novel applications with smaller library sizes compared to prior technologies. Pooled functional genomics screens require high cellular coverage per perturbation to accurately quantify phenotypes and average out phenotype-independent variability across the population. While more compact libraries have decreased the number of cells needed for a given screen, the cell coverage required for large-scale CRISPR screens still poses technical hurdles to screen in more challenging systems, such as iPSC-derived and primary cells. A major factor that influences cell coverage is screening library uniformity, as larger variation in individual guide RNA abundance requires higher cell coverage to reliably measure low-abundance guides. In this work, we have systematically optimized guide RNA cloning procedures to decrease bias. We implement these protocols to demonstrate that CRISPRi screens using 10-fold fewer cells than the current standard provides equivalent statistically significant hit-calling results to screens run at higher coverage, opening the possibility of conducting genome-wide and other large-scale CRISPR screens in technically challenging models.
2023-01-10 | GSE222531 | GEO
Project description:Epigenetic profiles guide optimized CRISPR/Cas9-mediated gene knockout in human T cells
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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:Since the creation of Dolly, the first sheep cloned via somatic cell nuclear transfer (SCNT), in 1997, more than a dozen species of mammals have been cloned using this technology. One hypothesis for the limited success of cloning via SCNT (1-5%) is that the clones are likely derived from adult stem cells, which form an extremely small fraction in most adult tissues. Support for this hypothesis is that the cloning efficiency of full term development using embryonic stem (ES) cells as nuclear donors is 5-10 times higher than that for somatic cells as nuclear donors. Additionally, cloned pups could not be produced directly from cloned embryos derived from nuclei of differentiated B and T cells or neuronal cells. The question remains: can SCNT-derived animal clones be derived from truly differentiated somatic cells? We tested this hypothesis with mouse hematopoietic cells at different differentiation stages: hematopoietic stem cells (HSCs), progenitor cells (HPCs), and granulocytes. Surprisingly, we found that cloning efficiency increases over the differentiation hierarchy. The terminally differentiated post-mitotic granulocytes yielded the greatest cloning efficiency and we produced two cloned pups from granulocytes. We conclude that cloned mammals could be directly derived from post-mitotic differentiated somatic cells. Keywords: cell type comparison
2006-10-01 | GSE5677 | GEO
Project description:The loss of compact myocardial cardiomyocyte (compact CM) identity suggests that PRDM16 deficiency may dramatically alter the cellular composition in left ventricular (LV) compact myocardium. To test this hypothesis, we performed single-cell RNA-seq (scRNA-seq) to examine gene dysreulation in Prdm16cKO heart. We also performed Visium Spatial Transcriptomics (ST) to facilitate mapping CM clusters to their original locations in the heart. As a result, we were able to demonstrate gene misregulation in Prdm16cKO mouse mainly occurred in LV compact CM.
2021-12-20 | GSE179392 | GEO
Project description:The loss of compact myocardial cardiomyocyte (compact CM) identity suggests that PRDM16 deficiency may dramatically alter the cellular composition in left ventricular (LV) compact myocardium. To test this hypothesis, we performed single-cell RNA-seq (scRNA-seq) to examine gene dysreulation in Prdm16cKO heart. We also performed Visium Spatial Transcriptomics (ST) to facilitate mapping CM clusters to their original locations in the heart. As a result, we were able to demonstrate gene misregulation in Prdm16cKO mouse mainly occurred in LV compact CM.
2021-12-20 | GSE179390 | GEO
Project description:Engineered transactivation domains (TADs) combined with programmable DNA binding platforms have revolutionized synthetic transcriptional control. Despite recent progress in programmable CRISPR/Cas-based transactivation (CRISPRa) technologies, the TADs used in these systems often contain poorly tolerated elements and/or are prohibitively large for many applications. Here we defined and optimized minimal TADs built from human mechanosensitive transcription factors (MTFs). We used these components to construct potent and compact multipartite transactivation modules (MSN, NMS, and eN3×9) and to build the CRISPR-dCas9 recruited enhanced activation module (CRISPR-DREAM) platform. We found that CRISPR-DREAM was specific, robust across mammalian cell types, and efficiently stimulated transcription from diverse regulatory loci. We also showed that MSN and NMS were portable across Type I, II, and V CRISPR systems, TALEs, and ZF proteins. Further, as proofs of concepts, we used dCas9-NMS to efficiently reprogram human fibroblasts into iPSCs and demonstrated that MTF TADs are efficacious and well tolerated in therapeutically important primary human cell types. Finally, we leveraged the compact and potent features of these engineered TADs to build new dual and all-in-one CRISPRa AAV systems. Altogether, these compact human TADs, fusion modules, and new delivery architectures should be valuable for synthetic transcriptional control in biomedical applications.
2023-07-31 | GSE238178 | 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:Cloning mammals by somatic cell nuclear transfer (SCNT) is highly inefficient because of aberrant genomic reprogramming. In addition to random reprogramming errors, we hypothesized the presence of specific errors as evidenced by common anomalies among clones. We found that Xist, which normally inactivates one of the two X chromosomes in females, was ectopically expressed from the active X (Xa) chromosome in cloned mouse embryos of both sexes. Deletion of Xist on Xa normalized global gene expression and produced about a 10-fold increase in cloning efficiency. We also identified an Xist-independent mechanism that specifically downregulated a subset of X-linked genes through somatic-type repressive histone blocks. Thus, we have identified nonrandom reprogramming errors in mouse cloning, which provide promising targets for breakthroughs in SCNT cloning technology.
2010-09-16 | GSE23181 | GEO