Sub-lethal oxidative stress induces lysosome biogenesis via a lysosomal membrane permeabilization-cathepsin-caspase 3-transcription factor EB-dependent pathway

// San Min Leow 1,2 , Shu Xian Serene Chua 1 , Gireedhar Venkatachalam 1,2 , Liang Shen 3 , Le Luo 1 and Marie-Veronique Clement 1,2 1 Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore 2 National University of Singapore Graduate School for Integrative Sciences and Engineering, Singapore, Singapore 3 Biostatistic Unit, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore Correspondence to: Marie-Veronique Clement, email: // Keywords : sub-lethal oxidative stress, lysosomal membrane permeabilization, caspase 3, transcription factor EB, lysosomes, Autophagy Received : January 24, 2016 Accepted : December 05, 2016 Published : December 18, 2016 Abstract Here we provide evidence to link sub-lethal oxidative stress to lysosome biogenesis. Exposure of cells to sub-lethal concentrations of exogenously added hydrogen peroxide resulted in cytosol to nuclear translocation of the Transcription Factor EB (TFEB), the master controller of lysosome biogenesis and function. Nuclear translocation of TFEB was dependent upon the activation of a cathepsin-caspase 3 signaling pathway, downstream of lysosomal membrane permeabilization and accompanied by a significant increase in lysosome numbers as well as induction of TFEB-dependent lysosome-associated genes expression such as Ctsl , Lamp2 and its spliced variant Lamp2a , Neu1 , Ctsb , Sqstm1 , and Atg9b . The effects of sub-lethal oxidative stress on lysosomal gene expression and biogenesis were rescued upon gene silencing of caspase 3 and TFEB. Notably, caspase 3 activation was not associated with phenotypic hallmarks of apoptosis, evidenced by the absence of caspase 3 substrate cleavage, such as PARP, Lamin A/C or gelsolin. Taken together, these data demonstrate for the first time an unexpected and non-canonical role of a cathepsin-caspase 3 axis in the nuclear translocation of TFEB leading to lysosome biogenesis under conditions of sub-lethal oxidative stress.