Characterization of a C57BL/6J Fancg-KO Mouse Model Generated by CRISPR/Cas9

Fanconi anemia (FA) develops due to a mutation in one of the FANC genes that are involved in repair of interstrand crosslinks (ICLs). FANCG, a member of the FA core complex, is essential for ICL repair. Previous FANCG-deficient mouse models were generated with drug-based selection cassettes in mixed mice backgrounds, leading to a disparity in interpretation of genotype-related phenotype. To exclude these confounders, we created a Fancg-KO (KO) mouse model using CRISPR/Cas9. The entire Fancg locus was targeted and maintained on the immunological well-characterized C57BL/6J background. Intercrossing of heterozygous mice resulted in sub-Mendelian numbers of homozygous mice, suggesting loss of FANCG can be embryonic lethal. KO mice displayed infertility, hypogonadism but no other developmental problems. Bone marrow analysis revealed a defect in various hematopoietic stem and progenitor subsets with a bias towards myelopoiesis. Cell lines derived from Fancg-KO mice were hypersensitive to crosslinking agents-cisplatin and Mitomycin C, and Fancg-KO mouse embryonic fibroblasts (MEFs) displayed increased γ-H2AX upon cisplatin treatment. Reconstitution of these MEFs with Fancg cDNA corrected for the ICL hypersensitivity. Collectively, this project provides a new, genetically and immunologically well-defined Fancg-KO mouse model for further in vivo and in vitro studies on FANCG and ICL repair.