ATR was required for the induction of TP53-dependent autophagy in Beas-2B cells upon PM2.5 exposure. (A) Beas-2B cells were treated as described in Fig. 1A, and then the activation status of ATM and ATR was determined. (B) Beas-2B cells were transfected with ATR siRNA, ATM siRNA or control siRNA; then, cells were treated with PM2.5 (100 μg/mL) 36 h after transfection. The activation status of TP53 and the expression levels of ATR, ATM, DRAM1, BECN1 and MAP1LC3B were examined 24 h after PM2.5 exposure. (C) Beas-2B cells stably transfected with TP53-dependent luciferase reporter were transfected with ATR siRNA, ATM siRNA or control siRNA; then exposed to PM2.5 (100 μg/mL) 36 h after transfection. The induction of TP53-dependent luciferase activity was determined 12 h after PM2.5 exposure (**, P < 0.01). (D and E) Beas-2B cells were transfected with ATR siRNA or control siRNA and then treated with PM2.5 (100 μg/mL) 36 h after transfection. The autophagy signals were detected as described in Fig. 2C and 2D (**, P < 0.01). p, phosphorylated.