Fig. 1

Oxidative stress is involved in the pathogenesis of DKD. Copper/zinc superoxide dismutase (Cu/ZnSOD) and manganese superoxide dismutase (MnSOD) catalyze the mutation (or distribution) of superoxide (O₂^• −) radicals to hydrogen peroxide (H₂0₂) in the mitochondrial membrane space (IMS) and matrix, respectively. Hydrogen peroxide (H₂O₂) is converted to water by catalase (CAT) and a group of glutathione peroxidases (gpx) and peroxide reductases (Prxs). H₂O₂ spreads easily to other parts of the mitochondria or cytoplasm. O₂—reacts with nitric oxide (NO•) to produce peroxynitrite (ONOO-), ONOO- decomposes into highly oxidized intermediates such as NO₂ ⁻ , OH•, CO₃ ⁻ , etc., and finally forms stable NO₃ ⁻ . NF-κB, nuclear factor κB; Nrf2, nuclear factor (erythroid-derived 2)-like 2; PARP-1, poly (ADP-ribose) polymerases; FOXO, forkhead box protein O. ROS, reactive oxygen species