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.
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.
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.
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.
Project description:RNA interference (RNAi) technology is widely used in basic and translational research. By mimicking natural primary microRNA (pri-miRNA) cluster, multiple engineered hairpins can be transcribed as a single transcript from the same Pol-II promoter, enabling multiplex RNAi in mammalian cells 1-5. However, constructing synthetic miRNA cluster is still time-consuming, and the processing and function of miRNA cluster are incompletely understood. Here, we identified a miRNA precursor architecture that allowed precise miRNA maturation. We established a hierarchical cloning method for efficient construction of synthetic miRNA cluster harboring up to 18 miRNA precursors. We demonstrated that maturation and function of individual miRNA precursors were independent on their positions in the cluster. We then analyzed the integration efficiency of miRNA clusters with varying number of miRNA precursors by using CRISPR/Cas9 mediated integration, piggyBac transposon system, and lentiviral system. This synthetic miRNA cluster system provides an important tool for multiplex RNAi in mammalian cells.
2016-09-01 | GSE71088 | GEO
Project description:Novel Cas12a Orthologs for Highly Efficient Genome Editing in Plants
Project description:CRISPR/Cas12a-based combinational screening has shown remarkable potential in identifying genetic interactions. Here, we described an innovative method for combinational genetic screen with rapid constructing of dual-crRNA library by gene splicing through overlap extension PCR (SOE PCR) and the adoption of CeCas12a, which was identified previously by us with strict PAM recognition and low off- targeting, to guarantee the fidelity and efficiency. The custom, pooled SOE crRNA array (SOCA) library for double knockout screen could be conveniently constructed in lab for widespread use and CeCas12a mediated high fidelity screen display good performances even under negative selection screen. By designing an SOCA dual-crRNA library which covered the most of kinase and metabolism-associated gene targets of FDA- approved drugs that were implicated in hepatocellular carcinoma (HCC) tumorigenesis, novel cross talks between the two gene sets were negatively selected out to synergistically inhibit HCC cell growth in vitro and in vivo and also validated by virtual double knockdown screening based on TCGA databases. Thus through our rapid, efficient and high fidelity double knockout screening system, it is very promising to systemically dig genetic interactions between multiple gene sets or synergistic combinations of FDA-approved drugs for clinical translational medicine in the future.
Project description:CRISPR/Cas12a-based combinational screening has shown remarkable potential in identifying genetic interactions. Here, we described an innovative method for combinational genetic screen with rapid constructing of dual-crRNA library by gene splicing through overlap extension PCR (SOE PCR) and the adoption of CeCas12a, which was identified previously by us with strict PAM recognition and low off- targeting, to guarantee the fidelity and efficiency. The custom, pooled SOE crRNA array (SOCA) library for double knockout screen could be conveniently constructed in lab for widespread use and CeCas12a mediated high fidelity screen display good performances even under negative selection screen. By designing an SOCA dual-crRNA library which covered the most of kinase and metabolism-associated gene targets of FDA- approved drugs that were implicated in hepatocellular carcinoma (HCC) tumorigenesis, novel cross talks between the two gene sets were negatively selected out to synergistically inhibit HCC cell growth in vitro and in vivo and also validated by virtual double knockdown screening based on TCGA databases. Thus through our rapid, efficient and high fidelity double knockout screening system, it is very promising to systemically dig genetic interactions between multiple gene sets or synergistic combinations of FDA-approved drugs for clinical translational medicine in the future.
Project description:CRISPR/Cas12a-based combinational screening has shown remarkable potential in identifying genetic interactions. Here, we described an innovative method for combinational genetic screen with rapid constructing of dual-crRNA library by gene splicing through overlap extension PCR (SOE PCR) and the adoption of CeCas12a, which was identified previously by us with strict PAM recognition and low off- targeting, to guarantee the fidelity and efficiency. The custom, pooled SOE crRNA array (SOCA) library for double knockout screen could be conveniently constructed in lab for widespread use and CeCas12a mediated high fidelity screen display good performances even under negative selection screen. By designing an SOCA dual-crRNA library which covered the most of kinase and metabolism-associated gene targets of FDA- approved drugs that were implicated in hepatocellular carcinoma (HCC) tumorigenesis, novel cross talks between the two gene sets were negatively selected out to synergistically inhibit HCC cell growth in vitro and in vivo and also validated by virtual double knockdown screening based on TCGA databases. Thus through our rapid, efficient and high fidelity double knockout screening system, it is very promising to systemically dig genetic interactions between multiple gene sets or synergistic combinations of FDA-approved drugs for clinical translational medicine in the future.