The Interplay Between Reactive Oxygen Species, Glucose Metabolism and NF-kB in the Pathogenesis of Type 2 Diabetes

Reactive oxygen species (ROS) are an essential component for the maintenance of cellular function. However, if produced in excess, ROS can drive cellular dysfunction and compromise cell viability. Indeed, uncontrolled ROS production plays a pivotal role in the pathogenesis of type 2 diabetes (T2D), contributing to the loss of β-cell function and the impairment in insulin signalling, as well as driving the development of diabetic complications, which can severely compromise quality of life. T2D is characterised by persistent hyperglycaemia, which is a leading contributor to ROS overproduction in this disease state. This enhanced, almost uncontrolled, increase in glucose metabolism upregulates several ROS-producing pathways, including the hexosamine pathway, protein kinase C, NADPH oxidase and the mitochondrial electron transport chain. There is accumulating evidence to suggest that in a bid to preserve redox homeostasis, ROS acts to suppress glucose metabolism by inactivating several enzymes involved in the regulation of glycolytic flux, including glucokinase, glyceraldehyde 3-phosphate dehydrogenase, phosphofructokinase-1 and pyruvate kinase. Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) is a multi-faceted transcription factor, with a central role in ROS signalling and redox homeostasis. Whilst NF-κB mediates the transcriptional regulation of many pro-oxidants, NF-κB activity is also regulated by the oxidative status, with ROS having both inhibitory and stimulatory roles in these signalling pathways. Interestingly, NF-κB is also involved in controlling the delicate balance between glycolytic flux and mitochondrial respiration. This review will summarise the interplay linking hyperglycaemia with ROS formation, emphasising the role of glucose metabolism in the process, and the crosstalk of these pathways with NF-κB.