LAUSR

Bafilomycin-A1 is known for its lysosomal V-ATPase targeting, irrespective of cell types. Recently ML9, prevents store-operated Ca2+ entry, also reported for targeting the lysosomes and causing cell death. However, no study has been performed on the mechanism of lysosome targeting of bafilomycin and ML9. Here and, using cardiomyocytes, we observed 8 h pre-incubation of ML9 leads a significant cell death, but longer treatment was needed for bafilomycin. But surprisingly the death is not associated with ROS or ATP production. The FACS study with lysotracker green and LC3II expression levels, as well as the LC3-GFP puncta formation, are in support of lysosomotropic nature both of bafilomycin and of ML9 but significant differences on lysosomotropicity were not observed upon both of the treatments. However, in a molecular docking study, we found bafilomycin-A1 as a better inhibitor of V-ATPase towards C1 and C2 domains than ML9. In conclusion, at this stage, V-ATPase may not be associated with death program, but ML9 may induce lysosomal membrane permeabilization to release the lysosomal protease in the cytosol for causing cell death.