Studies on the gene expression of several NADPH oxidase components

Abstract

Introduction The NADPH oxidase is an enzymic system found in professional phagocytes (neutrophils, eosinophils, monocytes and macrophages) that catalyses the one-electron reduction of oxygen to 0; [ 11. This 0; and the toxic oxygen molecules derived from it are produced by phagocytes during the process of respiratory burst after exposure to appropriate stimuli, and are used for the killing and destruction of invading microbes and tumour cells [2]. NAIIPH oxidase is believed to be an electron transport chain whose components have been only in part completely identified (see [ 3, 41 for detailed reviews), characterized and cloned [ 5lo]. Cloning has been obtained especially through investigations of patients affected by chronic granulomatous disease (CGD), in whom NADPH oxidase functioning is defective because of abnormalities of its different polypeptides. The terminal component of the NADPH oxidase chain is a membrane-associated low potential haem protein, cytochrome bSSX, which is a heterodimer composed of two subunits [ 111: a 91 kDa chain (gp91-phox) and a 22 kDa chain (p22-phox). The other cloned components reside in the cytosol and both move into the membrane upon cell triggering [ 12, 131: a 47 kDa protein that undergoes phosphorylation during NADPH oxidase stimulation (p47-phox) [14] and a 67 kDa peptide (p67-phox), some functional aspects of which have been described [ 151.