P53 ICE CRIM mouse: a tool to generate mutant allelic series in somatic cells and germ lines for cancer studies

The clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 technology facilitates somatic genome editing to reveal cooperative genetic interactions at the cellular level without extensive breeding between different mutant animals. Here we propose a transgenic inducible Cas9 effector–CRISPR mutagen (ICE CRIM) mouse model in which CRISPR/Cas9–mediated somatic mutagenesis events can occur in response to Cre expression. The well-known tumor suppressor gene, Trp53, and 2 important DNA mismatch repair genes, Mlh1 and Msh2, were selected to be our somatic mutagenesis targets. Amplicon-based sequencing was performed to validate the editing efficiency and to identify the mutant allelic series. Crossed with various Cre lines, the Trp53 ICE CRIM alleles were activated to generate targeted cancer gene somatic or germ line mutant variants. We provide experimental evidence to show that an activated ICE CRIM can mutate both targeted alleles within a cell. Simultaneous disruption of multiple genes was als...