Improvements to Cas9-Mediated Mutation

Patent Status

Brief Description

Cas9 is an RNA-guided DNA endonuclease used to perform targeted genomic manipulations, which can include the error-prone knockout of sequences via non-homologous end joining (NHEJ) and the introduction of precise edits via homology directed repair (HDR). HDR editing shows great promise for a variety of uses, such as generating new cellular immunotherapies, curing genetic disease, and introducing traits into agricultural crops. Yet the efficiency of HDR has lagged behind that of NHEJ, complicating these exciting applications. Additionally, worries have arisen about unintended knockout from off-target NHEJ.

UC Berkeley researchers have found that Cas9 operates by a surprising mechanism, which suggested ways to improve HDR. Taking advantage of this mechanism, researchers found simple methods to dramatically increase the efficiency of HDR, introducing targeted mutations in human cells with frequencies around 60%. Additionally, catalytically inactive Cas9 can be used to make mutations via HDR without attendant error-prone NHEJ. This latter activity allows the precise introduction of mutations with no danger of undesired knockout at off-target sequences.

Suggested uses

• Precision gene editing in therapeutic contexts
• Introduction of desired traits in crops
• Generation of genetically modified organisms
• Isogenic cell line generation

Advantages

Publication

Enhancing homology-directed genome editing by catalytically active and inactive CRISPR-Cas9 using asymmetric donor DNA