Mitochondrial H2O2 Generation Using a Tunable Chemogenetic Tool To Perturb Redox Homeostasis in Human Cells and Induce Cell Death.

Among reactive oxygen species (ROS), H2O2 alone acts as a signaling molecule that promotes diverse phenotypes depending on the intracellular concentration. Mitochondria have been suggested as both sources and sinks of cellular H2O2, and mitochondrial dysfunction has been implicated in diseases such as cancer. A genetically encoded H2O2 generator, d-amino acid oxidase (DAAO), was targeted to the mitochondria of human cells, and its utility in investigating cellular response to a range of H2O2 doses over time was assessed. Organelle-specific peroxiredoxin dimerization and protein S-glutathionylation were measured as indicators of increased H2O2 flux due to the activity of DAAO. Cell death was observed in a concentration- and time-dependent manner, and protein oxidation shifted in localization as the dose increased. This work presents the first systematic study of H2O2-specific perturbation of mitochondria in human cells, and it reveals a marked sensitivity of this organelle to increases in H2O2 in comparison with prior studies that targeted the cytosol.