Phagocyte-like NADPH oxidase [Nox2] in cellular dysfunction in models of glucolipotoxicity and diabetes

Abstract

Increased intracellular generation of reactive oxygen species [ROS] has been implicated in the pathology of metabolic [diabetes] and neurodegenerative [Alzheimer's] diseases. Accumulating evidence suggests NADPH oxidases [Noxs] as the principal source for cellular ROS in humans. Of this class of enzymes, the phagocyte-like Nox [Nox2] has come under intense scrutiny as one of the “culprits” for the induction of cellular damage culminating in the onset of diabetes and its complications. Functional regulation of Nox2 is fairly complex due to its membranous [gp91phox, p22phox] and cytosolic [p40phox, p47phox, p67phox and Rac1] cores, which require specific post-translational modification steps [phosphorylation and lipidation] for their membrane association. Therefore, optimal efficacy of Nox2 depends upon precise regulation of these signaling steps followed by translocation of the cytosolic components to the membrane. Interestingly, numerous recent studies have reported sustained activation of Nox2, ROS-derived oxidative stress, and cellular dysfunction in in vitro and in vivo models of glucolipotoxicity and diabetes. These investigations employed a variety of cell-permeable peptides and pharmacological inhibitors to impede Nox2 holoenzyme assembly and activation in pancreatic islet β-cells, cardiomyocytes and retinal endothelial cells under conditions of glucolipotoxicity and diabetes. Herein, we highlight the existing evidence to implicate Nox2 as the “trigger” of cellular damage, and identify critical gaps in our current understanding that need to be addressed to further affirm the roles of Nox2 as a potential therapeutic target for the treatment of diabetes and other metabolic disorders.