Nitric oxide and mechanisms of redox signaling

Regulation of signal transduction and gene expression is a multifaceted process involving ligands, receptors, and second messengers that trigger cascades of protein kinases and phosphatases and propagate the signal to the nucleus to alter gene expression. Reduction Reduction-oxidation (redox)-based regulatory pathways provide additional means of gating signal transduction, and redox-based regulation of gene expression emerges as a fundamental regulatory mechanism in living cells. The cellular redox state is reflected by the degree of oxidation (or reduction) of various redox-active molecules at a specific cellular location at any given time point. The ratio of oxidized/reduced redox species determines the redox potential, which may vary dramatically in time and in different compartments of a cell and consequently alter in a temporally and spatially dynamic process the activity of signaling enzymes that carry redox-active functional groups. Generation and action of free radicals such as nitric oxide, superoxide, and H2O2 that para-digmatically-highlight the impact of redox regulation on cellular signal transduction and gene expression are discussed with a special focus on the renal glomerular response to injury.