| Cas9 is the nuclease guided by the crRNA and tracrRNA (or trans-activating crRNA) to cleave specific DNA sequences. A guide RNA (gRNA) can be designed to include a hairpin that mimics the tracrRNA-crRNA complex. Binding specificity is based on the gRNA and a three nucleotide NGG sequence called the protospacer adjacent motif (PAM) sequence. With its ease in designing guide sequences to target specific genomic loci, the CRISPR/Cas system is a much simpler, faster, and robust alternative to TALEN and Zinc finger nuclease platforms. For site-specific genome editing, the CRISPR/Cas9 system requires the Cas 9 nuclease and the gRNA. This RGD-fiber modified adenovirus expresses a codon-optimized spCas9. It can be used along with guided RNA for genome-editing in cells that regular Ad5 doesnt infect well, including human or mouse macrophages, ES cells, T cells, synoviocytes, certain fibroblast and islet grafts etc. |
