Novel gp91 ^phox Homologues in Vascular Smooth Muscle Cells

Abstract

Abstract-Emerging evidence indicates that reactive oxygen species are important regulators of vascular function. Although NAD(P)H oxidases have been implicated as major sources of superoxide in the vessel wall, the molecular identity of these proteins remains unclear. We recently cloned nox1 (formerly mox-1), a member of a new family of gp91 phox homologues, and showed that it is expressed in proliferating vascular smooth muscle cells (VSMCs). In this study, we examined the expression of three nox family members, nox1, nox4, and gp91 phox , in VSMCs, their regulation by angiotensin II (Ang II), and their role in redox-sensitive signaling. We found that both nox1 and nox4 are expressed to a much higher degree than gp91 phox in VSMCs. Although serum, platelet-derived growth factor (PDGF), and Ang II downregulated nox4, they markedly upregulated nox1, suggesting that this enzyme may account for the delayed phase of superoxide production in these cells. Furthermore, an adenovirus expressing antisense nox1 mRNA completely inhibited the early phase of superoxide production induced by Ang II or PDGF and significantly decreased activation of the redox-sensitive signaling molecules p38 mitogen-activated protein kinase and Akt by Ang II. In contrast, redox-independent pathways induced by PDGF or Ang II were unaffected. These data support a role for nox1 in redox signaling in VSMCs and provide insight into the molecular identity of the VSMC NAD(P)H oxidase and its potentially critical role in vascular disease. (Circ Res. 2001;88:888-894.)

Novel Human Homologues of p47 and p67 Participate in Activation of Superoxide-producing NADPH Oxidases

“…3), respectively. On the other hand, it is known that vascular smooth muscle cells express Nox1 (57) and produce superoxide in a stimulus-dependent manner (37). As expected from the dependence, p47 phox exists in the cells and plays a crucial role in superoxide production (58), whereas the cells do not contain p67 phox (37), raising the possibility that p51 nox may be present instead.…”

Inhibition of NADPH oxidase 4 activates apoptosis via the AKT/apoptosis signal-regulating kinase 1 pathway in pancreatic cancer PANC-1 cells

“…Although they share common structural similarities with six transmembrane domains and the cytoplasmic domain that comprises NADPH-and FAD-binding sites, each member appears to exert a specific biological role through superoxide generation. For example, the best-studied Nox2 (gp91phox) is responsible for host defense against microorganism invasion (Bokoch, 1994), Nox1 mediates PDGF- (Suh et al, 1999) or EGF- (Mitsushita et al, 2004) stimulated mitogenesis in fibroblast cells and angiotensin-induced proliferation in vascular smooth muscle cells (Lassegue et al, 2001), and Nox4 is coupled to insulin signal transduction including glucose uptake in adipocytes (Mahadev et al, 2004) and Toll-like receptor 4-mediated inflammation (Park et al, 2004).…”

Expression of Nox1 in 3T3 cells increases cellular acid production but not proton conductance

“…4E, lines) resulted in halfmaximal block at 276 ± 50 μM (mock 3T3) and 265 ± 114 μM (Nox1 3T3, p > 0.5). Expression of Nox1 had no measurable effects on blocker kinetics by ZnSO 4 .…”

“…Basal pH i was similar in both cell types (mock 3T3, 6.958 ± 0.157, n = 3; Nox1 3T3, 6.963 ± 0.22, n = 6). To investigate the production of intracellular acid, cells were treated with 30 mM NH 4 Cl added to the bath solution (equimolar exchange for NaCl at constant pH). This resulted in a rapid alkalinization of the cytosol (Fig.…”

“…5A). Kinetics of pH i acidification in presence of NH 4 Cl were quantified by determining the time constants (τ) of reacidification for individually measured cells, as shown in Fig. 5B.…”