Mesangial deposition of extracellular matrix (ECM) is a hallmark of several glomerular diseases including diabetic nephropathy. Accumulation of advanced oxidation protein products (AOPPs) has been found in diabetes and chronic kidney disease and linked to mesangial ECM deposition and progressive glomerulosclerosis in these disorders. Although emerging evidence implicates AOPPs as the renal pathogenic factors, the underlying mechanisms have not been investigated. Here, using cultured rat mesangial cell (MC) as a model, we identify AOPPs as the important mediators for activation of MC NADPH oxidase. Exposure of MCs to AOPPs, through membrane-associated phosphorylation of protein kinase C (PKC), induced rapid phosphorylation of cytosolic p47^phox and its membrane translocation, enhanced interaction of p47^phox with the membrane components p22^phox and Nox4, and increased expression of these key regulatory subunits of NADPH oxidase. AOPPs challenge triggered cytosolic superoxide generation, resulting in upregulation of fibronectin and collagen IV genes and proteins and overexpression of TGF-1 via a PKC-NADPH oxidase-dependent pathway, as these downstream events were blocked by the inhibitors of PKC, inhibitors of NADPH oxidase, or the cytosolic superoxide scavenger. These data provide new information for understanding the molecular basis underlying AOPPs-induced MC perturbation and might be a central step toward development of new intervention.