In the Edit-R Lentiviral sgRNA vector backbone, the gene-specific crRNA and the tracrRNA are expressed under the control of a human U6 promoter, while expression of the puromycin resistance marker (PuroR) is driven from the mouse CMV promoter and allows for rapid selection of cells with integrated sgRNA. The plasmid contains the AmpR resistance marker for growth and selection in E. coli.
The Edit-R Lentiviral CRISPR-Cas9 platform is a two-vector system that utilizes a lentiviral vector with multiple Pol II promoter options for maximal Cas9 expression and a gene-specific vector for sgRNA expression designed to the target site of interest.
10 crRNAs with high functional scores for 10 genes (blue bars) and 10 crRNAs with low functional scores for the same genes (yellow bars) were tested for editing by Next Generation Sequencing. 93% of the high-scoring crRNAs and 32 % of the low scoring crRNAs showed > 40% of editing (indel formation). The Cas9-HEK293T cell line was transfected with 50 nM crRNA:tracrRNA, using 0.25 µL/well of DharmaFECT 1. Seventy-two hours post-transfection, cells were lysed and Nextera transposon-adapted amplicons spanning each crRNA site were generated for every treated sample as well as for a matched control amplicon from untransfected samples. Samples were indexed using the Nextera 96-well index kit and pooled for sequencing on a MiSeq instrument (paired end reads, 2 x 300 length). Reads that passed NGS quality filtering criteria were aligned to the reference file (Bowtie2 v2.1.0). Percent perfect reads were calculated and normalized to the control untransfected samples (Samtools v0.1.12a); the data is presented as normalized percent edited.
Here we are targeting the gene PSMD11 at 12 different sites and measuring functionality by EGFP signal to indicate disruption of the proteasome. Cells were either transfected with crRNA:tracrRNAs, or transduced with lentiviral particles for expression of a sgRNA of the same design. There is no significant difference between the two guide RNA formats when targeting the same genomic site; a good design for crRNA will translate into a good design for sgRNA.