Project description:Development of the 3Cs multiplex technology for combinatorial screening and identification of genetic interactions among human autophagy genes in cell proliferation and autophagy flux.
Project description:CRISPR-based gene perturbation enables unbiased investigations of single and combinatorial genotype-to-phenotype associations. In light of efforts to map combinatorial gene dependencies at scale, choosing an efficient and robust CRISPR-associated (Cas) nuclease is of utmost importance. Even though SpCas9 and AsCas12a are widely used for single, combinatorial, and orthogonal screenings, side-by-side comparisons remain sparse. Here, we systematically compared combinatorial SpCas9, AsCas12a, and CHyMErA in hTERT-immortalized retinal pigment epithelial cells and extracted performance-critical parameters for combinatorial and orthogonal CRISPR screens. Our analyses identified SpCas9 to be superior to enhanced and optimized AsCas12a, with CHyMErA being largely inactive in the tested conditions. Since AsCas12a contains RNA processing activity, we used arrayed dual-gRNAs to improve AsCas12a and CHyMErA applications. While this negatively influenced the effect size of combinatorial AsCas12a applications, it enhanced the performance of CHyMErA. This improved performance, however, was limited to AsCas12a dual-gRNAs, as SpCas9 gRNAs remained largely inactive. To avoid the use of hybrid gRNAs for orthogonal applications, we engineered the multiplex SpCas9-enAsCas12a system (multiSPAS) that avoids RNA processing for efficient orthogonal gene editing.
Project description:Single-cell CRISPR screens allow for the exploration of mammalian gene function and genetic regulatory networks, but their utility has been limited in part by their reliance on indirect sgRNA indexing. Here, we present direct capture Perturb-seq, a versatile screening approach in which expressed sgRNAs are sequenced alongside single-cell transcriptomes. Direct capture Perturb-seq enables the detection of multiple distinct sgRNAs expressed from a single vector within individual cells and thus allows pooled single-cell CRISPR screens to be easily paired with combinatorial perturbation libraries. We demonstrate that this approach allows high-throughput investigations of genetic interactions, and we leverage this ability to dissect epistatic interactions between cholesterol biogenesis and DNA repair. We also show that targeting individual genes with multiple sgRNAs per cell improves the efficacy of CRISPR interference and activation, facilitating the use of compact, highly active CRISPR libraries for single-cell screens. Lastly, we show that hybridization-based target enrichment permits sensitive, specific sequencing of informative transcripts from single-cell RNA-seq experiments.
Project description:All bulk CRISPR based screens CD2 and B2M CRISPRi tiling screens (primary human CD8 T cells), IL2RA CRISPRa tiling screens (Jurkats), CRISPRi/a TF screens (primary human CD8 T cells), and CRISPR TFome KO (primary human T cells)
Project description:We have combined a machine-learning approach with other strategies to optimize the efficiency of sgRNAs for CRISPR screens and have constructed a genome-wide, sequence-verified, arrayed CRISPR library. This incorporates expression strategies to facilitate multiplexed or combinatorial screening. By conducting parallel loss-of-function screens, we compare our approach to existing sgRNA design and expression strategies.