Journal: Nature

Article Title: Saturation Editing of Genomic Regions by Multiplex Homology-Directed Repair

doi: 10.1038/nature13695

Figure Lengend Snippet: (a) Experimental schematic. Cultured cells were co-transfected with a single Cas9-sgRNA construct (CRISPR) and a complex homology-directed repair (HDR) library containing an edited exon that harbors a random hexamer (blue, green, orange) and a fixed selective PCR site (red). CRISPR-induced cutting stimulated homologous recombination with the HDR library, inserting mutant exons into the genomes of many cells. At five days post-transfection, cells were harvested for gDNA and RNA. After reverse transcription, selective PCR was performed followed by sequencing of gDNA and cDNA derived amplicons. Hexamer enrichment scores were calculated by dividing cDNA counts normalized by gDNA counts. (b) Correlation of enrichment scores between biological replicates for hexamers observed in each experiment with positions of previously identified exonic splicing enhancers (ESEs), exonic splicing silencers (ESSs) and stop codons indicated. (c) Rank-ordered plot of enrichment scores with positions of ESEs, ESSs, and stop codons indicated.

Article Snippet: A bicistronic Cas9-sgRNA vector designed to cleave within BRCA1 exon 18 (“pCas9-sgBRCA1x18”) was cloned according to a published protocol by ligating annealed oligonucleotides into a human codon-optimized S. pyogenous Cas9-sgRNA vector from the lab of Feng Zhang (pX330-U6-Chimeric_BB-CBh-hSpCas9; Addgene plasmid #42230).

Techniques: Cell Culture, Transfection, Construct, CRISPR, Random Hexamer Labeling, Homologous Recombination, Mutagenesis, Sequencing, Derivative Assay