Molecular Characterization and Localization of the\ud NAD(P)H Oxidase Components gp91-phox and p22-phox\ud in Endothelial Cells
- Publisher: American Heart Association
The production of reactive oxygen species (ROS) within endothelial cells may have several effects, including\ud alterations in the activity of paracrine factors, gene expression, apoptosis, and cellular injury. Recent studies indicate that\ud a phagocyte-type NAD(P)H oxidase is a major source of endothelial ROS. In contrast to the high-output phagocytic\ud oxidase, the endothelial enzyme has much lower biochemical activity and a different substrate specificity\ud (NADH.NADPH). In the present study, we (1) cloned and characterized the cDNA and predicted amino acid structures\ud of the 2 major subunits of rat coronary microvascular endothelial cell NAD(P)H oxidase, gp91-phox and p22-phox;\ud (2) undertook a detailed comparison with phagocytic NADPH oxidase sequences; and (3) studied the subcellular\ud location of these subunits in endothelial cells. Although these studies revealed an overall high degree of homology\ud (.90%) between the endothelial and phagocytic oxidase subunits, the endothelial gp91-phox sequence has potentially\ud important differences in a putative NADPH-binding domain and in putative glycosylation sites. In addition, the\ud subcellular location of the endothelial gp91-phox and p22-phox subunits is significantly different from that reported for\ud the neutrophil oxidase, in that they are predominantly intracellular and collocated in the vicinity of the endoplasmic\ud reticulum. This first detailed characterization of gp91-phox and p22-phox structure and location in endothelial cells\ud provides new data that may account, in part, for the differences in function between the phagocytic and endothelial\ud NAD(P)H oxidases.