Evidence for the Involvement of Distinct Signal Transduction Pathways in the Regulation of Constitutive and Interferon y-Dependent Gene Expression of NADPH Oxidase Components (gp91-phox, p47-phox, and p22-phox) and High-Affinity Receptor for IgG (FcyR-I) in Human Polymorphonuclear Leukocytes

We recently showed that mRNA levels coding the highaffinity Fcy receptor for IgG (FcyR-I, CD64) and two of the components of the phagocytic superoxide anion-generating system-the heavy-chain subunit of cytochrome b, , (gp91phox) and the 47-Kd cytosolic factor (p47-phox)-are modulated by interferon gamma (IFN-y). In this study, we examined whether dexamethasone (DEX) affects gp9l-phox and p47-phox mRNA expression of human polymorphonuclear leukocytes (PMN), treated or not with IFN-y. We also investigated whether staurosporine, a general inhibitor of protein kinases, influences gp9l-phox, p47-phox, and FcyR-l gene expression in PMN treated with or without IFN-y. We found that (1) gp9l-phox mRNA steady-state levels, expressed in control or IFN-ytreated PMN, were significantly inhibited, in a dose-dependent fashion, by both DEX and staurosporine; (2) p47-phox mRNA steady-state levels, expressed in control