Fig. 2

Caspase-12 activation plays a crucial role in M. smegmatis-mediated apoptosis. RAW 264.7 cells were infected with M. smegmatis (MOI = 5) for 0–24 h. a Western blot analysis of caspase-12, -9, and -3 levels. RAW 264.7 cells were pretreated with b the caspase-12 inhibitor z-ATAD-fmk (20 μM), c the caspase-9 inhibitor z-LEHD-fmk (20 μM), d the pan-caspase inhibitor z-VAD-fmk (20 μM), or e 4-PBA (10 mM) for 1 h and subsequently infected with M. smegmatis (MOI = 5) for 24 h. The activation of caspase-12, -9, and -3 was evaluated by western blotting. f RAW 264.7 cells were pretreated with caspase inhibitors and 4-PBA for 1 h and infected with M. smegmatis (MOI = 5) for 24 h. Apoptosis was measured by Annexin-V/PI staining. Data are means ± SDs of three independent experiments. *p < 0.05. M. smeg, Mycobacterium smegmatis; UN, uninfected; TM, tunicamycin; STS, staurosporine; 4-PBA, 4-phenylbutyric acid