Streamlined generation of CRISPR/Cas9-mediated single-cell knockout clones in murine cell lines

Clonal cell lines harbouring loss-of-function mutations in genes of interest are crucial for studying the cellular functions of the encoded proteins. Recent advances in genome engineering have converged on the CRISPR/Cas9 technology to quickly and reliably generate frameshift mutations in the target genes across various cell lines and species. Although high on-target cleavage efficiencies can be obtained reproducibly, screening and identifying clones with loss-of-function alleles remains a major bottleneck. Here, we describe a single sgRNA strategy to generate CRISPR/Cas9-mediated frameshift mutations in target genes of mammalian cell lines that can be easily and cost-effectively identified. Given the proliferation of workhorse cell lines such as HEK293 and N2a cells and the resulting clonal expansion of the cell type, our protocol can facilitate the isolation of knockout clonal cell lines and their genetic validation within a period of down to 3-4 weeks.