Ontology highlight
ABSTRACT:
PROVIDER: PRJNA1162663 | ENA |
REPOSITORIES: ENA
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Project description:Compact and versatile CRISPR-Cas systems will enable genome engineering applications through high-efficiency delivery in a wide variety of contexts. Here we create an efficient miniature Cas system (CasMINI) engineered from the type V-F Cas12f (Cas14) system by guide RNA and protein engineering, which is less than half the size of currently used CRISPR systems (Cas9 or Cas12a). We demonstrate that CasMINI can drive high levels of gene activation (up to thousands-fold increases), while the natural Cas12f system fails to function in mammalian cells. We show that the CasMINI system has comparable activities to Cas12a for gene activation, is highly specific, and allows for robust base editing and gene editing. We expect that CasMINI can be broadly useful for cell engineering and gene therapy applications ex vivo and in vivo.
2021-09-10 | GSE180773 | GEO
Project description:Cas12a CRISPR technology, unlike Cas9, allows for multiplexing guide RNAs from a single transcript, simplifying combinatorial perturbations. While Cas12a has been implemented for multiplexed knockout genetic screens, it has yet to be optimized for CRISPR activation (CRISPRa) screens in human cells. Here we develop a new Cas12a-based transactivation domain (TAD) recruitment system using the ALFA nanobody and demonstrate simultaneous activation of up to four genes. We screen a genome-wide library to identify modulators of growth and MEK inhibition, and we compare these results to those obtained with open reading frame (ORF) overexpression and Cas9-based CRISPRa. We find that the activity of multiplexed arrays is largely predictable from the best-performing guide and we provide criteria for selecting active guides. We anticipate that these results will greatly accelerate the exploration of gene function and combinatorial phenotypes at scale.
2023-05-08 | GSE230445 | GEO
Project description:Cas12a CRISPR technology, unlike Cas9, allows for multiplexing guide RNAs from a single transcript, simplifying combinatorial perturbations. While Cas12a has been implemented for multiplexed knockout genetic screens, it has yet to be optimized for CRISPR activation (CRISPRa) screens in human cells. Here we develop a new Cas12a-based transactivation domain (TAD) recruitment system using the ALFA nanobody and demonstrate simultaneous activation of up to four genes. We screen a genome-wide library to identify modulators of growth and MEK inhibition, and we compare these results to those obtained with open reading frame (ORF) overexpression and Cas9-based CRISPRa. We find that the activity of multiplexed arrays is largely predictable from the best-performing guide and we provide criteria for selecting active guides. We anticipate that these results will greatly accelerate the exploration of gene function and combinatorial phenotypes at scale.
2023-05-09 | GSE231789 | GEO
Project description:we characterized a novel compact Cas12a ortholog, EbCas12a, from the Erysipelotrichia bacterium with activities in mammalian cells. It is with the PAM sequence of 5’-TTTV-3’ (V=A, G, C) and the smallest size of ~3.47kb among reported Cas12a orthologs so far. Moreover, enhanced EbCas12a (enEbCas12a) was also developed to have comparable editing efficiency with higher specificity to AsCas12a and LbCas12a in mammalian cells. With the help of the compact enEbCas12a, all-in-one AAV delivery system with crRNA for Cas12a was developed for both in vitro and in vivo. Altogether, with the help of the novel smallest high fidelity enEbCas12a, this first case of the all-in-one AAV delivery for Cas12a could greatly boost future gene therapy and scientific research.
2023-07-10 | GSE236647 | GEO
Project description:The CRISPR-Cas12a platform has attracted interest in the genome editing community because the prototypic Acidaminococcus Cas12a generates a staggered DNA double-strand break upon binding to an AT-rich protospacer-adjacent motif (PAM, 5'-TTTV). The broad application of the platform in primary human cells was enabled by the development of an engineered version of the natural Cas12a protein, called Cas12a Ultra. In this study, we confirmed that CRISPR-Cas12a Ultra ribonucleoprotein complexes enabled allelic gene disruption frequencies of over 90% at multiple target sites in human T cells, hematopoietic stem and progenitor cells (HSPCs), and induced pluripotent stem cells (iPSCs). In addition, we demonstrated for the first time the efficient knock-in potential of the platform in human iPSCs and achieved targeted integration of a GFP marker gene into the AAVS1 safe harbor site and a CSF2RA super-exon into CSF2RA in up to 90% of alleles without selection. Clonal analysis revealed bi-allelic integration in >50% of the screened iPSC clones without compromising their pluripotency and genomic integrity. Thus, in combination with the adeno-associated virus vector system, CRISPR-Cas12a Ultra provides a highly efficient genome editing platform for performing targeted knock-ins in human iPSCs.
2024-02-09 | GSE249731 | GEO
Project description:CRISPR-Cas systems can be utilized as programmable-spectrum antimicrobials to combat bacterial infections. However, how CRISPR nucleases perform as antimicrobials across target sites and strains remains poorly explored. Here, we address this knowledge gap by systematically interrogating the use of CRISPR antimicrobials against multidrug-resistant and hypervirulent strains of Klebsiella pneumoniae. Comparing different Cas nucleases, we found that AsCas12a exhibited robust targeting across different strains. The elucidated modes of escape from this nuclease varied widely, restraining opportunities to enhance killing. We also encountered individual guide RNAs yielding different extents of clearance across strains. The differences were attributed to improper RNA folding, leading to inefficient DNA cleavage and subsequent repair via homologous recombination. To explore features that could improve targeting across strains, we performed a genome-wide screen in different K. pneumoniae strains that yielded guide design rules and trained an algorithm for predicting guide efficiency. Finally, we showed that Cas12a antimicrobials can be exploited to eliminate K. pneumoniae when encoded in phagemids delivered by T7-like phages. Altogether, our results highlight the importance of evaluating antimicrobial activity of CRISPR antimicrobials across relevant strains and define critical parameters for efficient CRISPR-based targeting.
2023-07-17 | GSE237136 | GEO
Project description:Transporters mediate and control the flux of molecules across compartmental membranes. The human genome encodes 1500 genes with transport functions, of which the solute carriers (SLCs) form the largest superfamily with more than 450 members. Over 250 different SLCs are expressed in a typical human cell, many exhibiting overlapping expression patterns and substrate specificities. The collective role of these often seemingly redundant transporters in defining cellular outcomes, such as cell survival, remains unclear. Here, we performed pooled combinatorial KO screens to identify genetic interactions between 258 expressed SLCs, and between a subset of SLCs and selected metabolic enzymes under different growth conditions using both CRISPR-Cas12a and -Cas9 double knockout systems in the colorectal carcinoma cell line HCT116.
2024-06-19 | GSE269905 | GEO