CRISPR-Cas9–based genetic screens are a powerful new tool in biology. By simply altering the sequence of the single-guide RNA (sgRNA), one can reprogram Cas9 to target different sites in the genome with relative ease, but the on-target activity and off-target effects of individual sgRNAs can vary widely. Here, we use recently devised sgRNA design rules to create human and mouse genome-wide libraries, perform positive and negative selection screens and observe that the use of these rules produced improved results. Additionally, we profile the off-target activity of thousands of sgRNAs and develop a metric to predict off-target sites. We incorporate these findings from large-scale, empirical data to improve our computational design rules and create optimized sgRNA libraries that maximize on-target activity and minimize off-target effects to enable more effective and efficient genetic screens and genome engineering.
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Sequence Read Archive
We thank M. Tomko, M. Greene, A. Brown, D. Alan and T. Green for software engineering support, and T. Nguyen, N. Tran and X. Yang for library production support (Broad Institute). Z.T. is funded by NIH 5K12CA087723-12, ASCO Young Investigator Award, LLS Special Fellow Award. J.G.D. is a Merkin Institute Fellow and is supported by the Next Generation Fund at the Broad Institute of MIT and Harvard.
Supplementary Table 1. Rounds of selection used to design Avana and Asiago library Supplementary Table 2. sgRNAs in the six subpools of Avana library Supplementary Table 3. sgRNAs in the six subpools of Asiago library Supplementary Table 4. Screening data for vemurafenib in A375 cells for all biological replicates screened with Avana libraries (divided by subpools) as well as GeCKOv1 and GeCKOv2 libraries Supplementary Table 5. RIGER analysis of vemurafenib screens using weighted-sum option Supplementary Table 6. STARS analysis of vemurafenib screens Supplementary Table 7. List of PanCancer genes Supplementary Table 8. Screening data for selumetinib in A375 cells for all biological replicates screened with Avana library Supplementary Table 9. STARS analysis of selumetinib screens Supplementary Table 10. Negative selection screening data in HT29 and A375 cells with GeCKO libraries Supplementary Table 11. Negative selection screening data in HT29 and A375 cells with GeCKO libraries and the set of 291 core essential genes annotated by Hart and colleagues Supplementary Table 12. STARS analysis of the negative selection screening data for GeCKO and Avana libraries individually Supplementary Table 13. STARS analysis of the negative selection screening data for GeCKO and Avana libraries merged Supplementary Table 14. Screening data for 6-thioguanine screen in 293T, A375 and HT29 cells Supplementary Table 15. Screening data for interferon-gamma treatment of BV2 cells and output of STARS analysis Supplementary Table 16. Screening data for the tiling of resistance genes Supplementary Table 17. Gini importance of individual features in the gradient-boosted regression tress model, Rule Set 2 Supplementary Table 18. Screening data for off-target analysis of CD33 in MOLM13 cells Supplementary Table 19. Percent-active, delta-log-fold-change, and one-sided Welch's t-test p-value calculations for the CD33 off-target dataset that is used to calculate the CFD score Supplementary Table 20. Activity of sgRNAs designed against H2-D1 that have up to 6 mismatches to H2-K Supplementary Table 21. sgRNAs in the Brunello library Supplementary Table 22. sgRNAs in the Brie library Supplementary Table 23. sgRNA sequences and primers used for individual follow-up experiments
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Genome Biology (2018)