Research Paper Volume 15, Issue 6 pp 1791—1807

Figure 1. Generation of an inducible suicidal mouse model of PD-L1 (PD- L1^ATTAC). (A) Scheme illustrating the construct used for the generation of PD-L1^ATTAC mice. The construct is under control of Cd274 promoter and codes for EGFP as a reporter gene and a FLAG-tagged caspase 8 fused to FKBP domains, which homodimerize in the presence of AP20187 and induce apoptosis of PD-L1⁺ cells. (B) Southern blot illustrating the presence of mESC clones harboring the correct integration of the PD-L1^ATTAC allele that were subsequently used for the generation of mutant mice. The 13.2 Kb band corresponds to the endogenous WT Cd274 gene, and the 8.5 Kb band to the knock-in PD-L1^ATTAC allele. (C) FACS analyses of PD-L1 expression as monitored by EGFP in PD-L1^ATTAC mESC cells harboring a dead Cas9 compatible with the SAM CRISPR activator system and transduced or not with a sgRNA against the Cd274 promoter. Percentage of EGFP+ cells is shown. (D) Representative picture from pairs of 3-month-old animals of the indicated genotypes.