Optimized methods to use Cas9 nickases in genome editing
The CRISPR-Cas9 system has emerged as one of the leading tools for modifying genomes of organisms ranging from E. coli to humans. One of the key components of this editing system is Cas9 endonuclease. The cleavage activity of the S. pyogenes Cas9 enzyme is mediated by the coordinated functions of two catalytic domains and creates blunt-ended, double-stranded breaks. Alanine substitution at key residues within these domains creates two Cas9 nickase variants. Variant D10A produces a nick on the targeting strand, while H840A nicks the non-targeting strand. This double nicking strategy can be leveraged to reduce unwanted off-target effect. However, the nickase experiments can be inherently more complicated than standard CRISPR-Cas9 editing, given the requirement for two guide RNAs to function simultaneously. In this webinar, both Shuqi Yan and Mollie Schubert present the data from the characterization of a number of factors that impact the efficiency of cooperative nicking in cell cultures. They also summarize a few key design considerations for achieving efficient gene disruption or homology directed repair (HDR) when planning your nickase experiments.
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