Genome-scale CRISPR-Cas9 knockout and transcriptional activation screening

Forward genetic screens are powerful tools for the unbiased discovery and functional characterization of specific genetic elements associated with a phenotype of interest. Recently, the RNA-guided endonuclease Cas9 from the microbial CRISPR (clustered regularly interspaced short palindromic repeats) immune system has been adapted for genome-scale screening by combining Cas9 with pooled guide RNA libraries. Here we describe a protocol for genome-scale knockout and transcriptional activation screening using the CRISPR-Cas9 system. Custom- or ready-made guide RNA libraries are constructed and packaged into lentiviral vectors for delivery into cells for screening. As each screen is unique, we provide guidelines for determining screening parameters and maintaining sufficient coverage. To validate candidate genes identified by the screen, we further describe strategies for confirming the screening phenotype, as well as genetic perturbation, through analysis of indel rate and transcriptional activation. Beginning with library design, a genome-scale screen can be completed in 9-15 weeks, followed by 4-5 weeks of validation.Paul & Daisy Soros Fellowships for New Americans (New York, N.Y.)McGovern Institute for Brain Research at MIT (Friends of McGovern Institute Fellowship)Massachusetts Institute of Technology. Poitras Center for Affective Disorders ResearchUnited States. Department of Energy (Computational Science Graduate Fellowship)National Institute of Mental Health (U.S.) (5DP1-MH100706)National Institute of Mental Health (U.S.) (1R01-MH110049)New York Stem Cell FoundationPoitras FoundationSimons FoundationPaul G. Allen Family FoundationVallee FoundationTom HarrimanB. Metcalf

Zinc Finger Nuclease mediated knockout of ADP dependent Glucokinase in Cancer cell lines: Effects on cell survival and Mitochondrial Oxidative Metabolism

<div><p>Zinc finger nucleases (ZFN) are powerful tools for editing genes in cells. Here we use ZFNs to interrogate the biological function of <i>ADPGK</i>, which encodes an ADP-dependent glucokinase (ADPGK), in human tumour cell lines. The hypothesis we tested is that ADPGK utilises ADP to phosphorylate glucose under conditions where ATP becomes limiting, such as hypoxia. We characterised two ZFN knockout clones in each of two lines (H460 and HCT116). All four clones had frameshift mutations in all alleles at the target site in exon 1 of <i>ADPGK,</i> and were ADPGK-null by immunoblotting. <i>ADPGK</i> knockout had little or no effect on cell proliferation, but compromised the ability of H460 cells to survive siRNA silencing of hexokinase-2 under oxic conditions, with clonogenic survival falling from 21±3% for the parental line to 6.4±0.8% (p = 0.002) and 4.3±0.8% (p = 0.001) for the two knockouts. A similar increased sensitivity to clonogenic cell killing was observed under anoxia. No such changes were found when <i>ADPGK</i> was knocked out in HCT116 cells, for which the parental line was less sensitive than H460 to anoxia and to hexokinase-2 silencing. While knockout of <i>ADPGK</i> in HCT116 cells caused few changes in global gene expression, knockout of <i>ADPGK</i> in H460 cells caused notable up-regulation of mRNAs encoding cell adhesion proteins. Surprisingly, we could discern no consistent effect on glycolysis as measured by glucose consumption or lactate formation under anoxia, or extracellular acidification rate (Seahorse XF analyser) under oxic conditions in a variety of media. However, oxygen consumption rates were generally lower in the <i>ADPGK</i> knockouts, in some cases markedly so. Collectively, the results demonstrate that <i>ADPGK</i> can contribute to tumour cell survival under conditions of high glycolytic dependence, but the phenotype resulting from knockout of <i>ADPGK</i> is cell line dependent and appears to be unrelated to priming of glycolysis in these lines.</p></div

The Role of Research in Viral Disease Eradication and Elimination Programs: Lessons for Malaria Eradication

Using their experiences from, and analysis of, global campaigns to eradicate smallpox, poliomyelitis, and measles, Myron Levine and colleagues derive lessons for malaria eradication

Rapid breeding of parthenocarpic tomato plants using CRISPR/Cas9

Parthenocarpy in horticultural crop plants is an important trait with agricultural value for various industrial purposes as well as direct eating quality. Here, we demonstrate a breeding strategy to generate parthenocarpic tomato plants using the CRISPR/Cas9 system. We optimized the CRISPR/Cas9 system to introduce somatic mutations effectively into SlIAA9—a key gene controlling parthenocarpy— with mutation rates of up to 100% in the T0 generation. Furthermore, analysis of off-target mutations using deep sequencing indicated that our customized gRNAs induced no additional mutations in the host genome. Regenerated mutants exhibited morphological changes in leaf shape and seedless fruit—a characteristic of parthenocarpic tomato. And the segregated next generation (T1) also showed a severe phenotype associated with the homozygous mutated genome. The system developed here could be applied to produce parthenocarpic tomato in a wide variety of cultivars, as well as other major horticultural crops, using this precise and rapid breeding technique

Unraveling CRISPR-Cas9 genome engineering parameters via a library-on-library approach.

We developed an in vivo library-on-library methodology to simultaneously assess single guide RNA (sgRNA) activity across ∼1,400 genomic loci. Assaying across multiple human cell types and end-processing enzymes as well as two Cas9 orthologs, we unraveled underlying nucleotide sequence and epigenetic parameters. Our results and software (http://crispr.med.harvard.edu/sgRNAScorer) enable improved design of reagents, shed light on mechanisms of genome targeting, and provide a generalizable framework to study nucleic acid-nucleic acid interactions and biochemistry in high throughput