Various membrane ATPases have been tested for their sensitivity to Bafilomycin A1, a macrolide antibiotic. Bafilomycin A1 is a specific and reversible inhibitor of vacuolar H⁺-ATPase (V-ATPase). It is used as an autophagy inhibitor at the late stage. Bafilomycin A1 blocks autophagosome-lysosome fusion and inhibits acidification and protein degradation in lysosomes of cultured cells. In addition, it induces apoptosis. Bafilomycin A1 also displays different types of membrane ATPases with the I₅₀ of 400 nmol/mg, 4 nmol/mg and 50 nmol/mg for the vacuolar ATPases of a fungus (N. crassa), a plant (Z. mays), and an animal (bovine abrenal medulla). The I₅₀ values refer as μmol of Bafilomycin A1 per mg of protein giving 50% inhibition of ATPase activity.

Bafilomycin A1, a macrolide antibiotic, is a specific and reversible inhibitor of V-ATPase and an autophagy inhibitor at the late stage.

Bafilomycin A1 disrupts autophagic flux by inhibiting both V-ATPase-dependent acidification and Ca-P60A/SERCA-dependent autophagosome-lysosome fusion. It at a low concentration (1 nM) effectively and specifically inhibits and kills pediatric B-cell acute lymphoblastic leukemia cells. Moreover, it also targets both early and late stages of the autophagy pathway, mitochondria and induces caspase-independent apoptosis. In addition, Bafilomycin A1 induces the binding of Beclin 1 to Bcl-2, which further inhibits autophagy and promotes apoptotic cell death. Furthermore, Bafilomycin A1 also inhibits the growth of a variety of cultured cells dose-dependently. They include golden hamster embryo and NIH-3T3 fibroblasts and PC12 and HeLa cells. The IC₅₀ of Bafilomycin A1 for inhibition of cell growth ranges from 10 to 50 nM.

In summary, Bafilomycin A1 is a potent and selective inhibitor of V-ATPases. Thus, it can study the physiological role of this class of enzymes. Bafilomycin A1 targets both autophagy and apoptosis pathways in pediatric B-cell acute lymphoblastic leukemia.

Reference:

Bowman EJ, et al. Proc Natl Acad Sci U S A. 1988;85(21):7972-7976.; Mauvezin C, et al. Autophagy. 2015;11(8):1437-1438.;Yuan N, et al. Haematologica. 2015;100(3):345-356.