Multiplexed inactivation of endogenous genes by base-editor-mediated multi-stop system

Base editor is also a powerful tool to introduce early stop codons to simultaneously silence multiple genes to study family gene function in embryo development. Here, we identified the highest efficiency base editing system (hA3A-eBE-Y130F) with few sgRNA independent off-target sites among six well-established base editors in mouse embryo. Further, we developed a Multi-Stop system to simultaneously knock-out all Ten-eleven translocation (TET) family of dioxygenase genes (Tet1, Tet2 and Tet3) in zygotic genome leads embryo die before 10.5 days of gestation. Moreover, we showed that inactivation of three DNA methyltransferases genes (Dnmt1, Dnmt3a and Dnmt3b) in zygote leads to gastrulation failure. We also obtained multiple TET and DNMT family genes (6KO: Dnmt1/3a/3b and Tet1/2/3; 5KO: Dnmt3a/3b and Tet1/2/3; 4KO: Dnmt1 and Tet1/2/3) deactivated mouse embryos in one step, which indicated that Dnmt1 or Dnmt3a/b is indispensable for mouse gastrulation. Overall design: We used the deep sequencing to evaluate the mutant efficiency of all the mutant embryos.