NOX4

About: NOX4 is a research topic. Over the lifetime, 1392 publications have been published within this topic receiving 85507 citations. The topic is also known as: KOX & KOX-1.

The NOX Family of ROS-Generating NADPH Oxidases: Physiology and Pathophysiology

Abstract: For a long time, superoxide generation by an NADPH oxidase was considered as an oddity only found in professional phagocytes. Over the last years, six homologs of the cytochrome subunit of the phag...

Vascular NAD(P)H oxidases: specific features, expression, and regulation

Abstract: The importance of reactive oxygen species (ROS) in vascular physiology and pathology is becoming increasingly evident. All cell types in the vascular wall produce ROS derived from superoxide-generating protein complexes similar to the leukocyte NADPH oxidase. Specific features of the vascular enzymes include constitutive and inducible activities, substrate specificity, and intracellular superoxide production. Most phagocyte enzyme subunits are found in vascular cells, including the catalytic gp91phox (aka, nox2), which was the earliest member of the newly discovered nox family. However, smooth muscle frequently expresses nox1 rather than gp91phox, and nox4 is additionally present in all cell types. In cell culture, agonists increase ROS production by activating multiple signals, including protein kinase C and Rac, and by upregulating oxidase subunits. The oxidases are also upregulated in vascular disease and are involved in the development of atherosclerosis and a significant part of angiotensin II-induced hypertension, possibly via nox1 and nox4. Likewise, enhanced vascular oxidase activity is associated with diabetes. Therefore, members of this enzyme family appear to be important in vascular biology and disease and constitute promising targets for future therapeutic interventions.

Novel gp91 phox Homologues in Vascular Smooth Muscle Cells : nox1 Mediates Angiotensin II–Induced Superoxide Formation and Redox-Sensitive Signaling Pathways

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.

Superoxide Production and Expression of Nox Family Proteins in Human Atherosclerosis

Abstract: Background— NAD(P)H oxidases are important sources of superoxide in the vasculature, the activity of which is associated with risk factors for human atherosclerosis. This study was designed to investigate the localization of superoxide production and the expression of the Nox family of NAD(P)H oxidase proteins (gp91phox, Nox1, and Nox4) in nonatherosclerotic and atherosclerotic human coronary arteries. Methods and Results— In coronary artery segments from explanted human hearts, we examined intracellular superoxide production with dihydroethidium. In nonatherosclerotic coronary arteries, superoxide was present homogenously throughout the intima, media, and adventitia. In atherosclerotic arteries, there was an additional intense area of superoxide in the plaque shoulder, which is rich in macrophages and α-actin–positive cells. p22phox colocalized with gp91phox mainly in macrophages, whereas Nox4 was found only in nonphagocytic vascular cells. Expression of gp91phox and p22phox mRNA was associated with the ...

Identification of renox, an NAD(P)H oxidase in kidney.

Abstract: Oxygen sensing is essential for homeostasis in all aerobic organisms, but its mechanism is poorly understood. Data suggest that a phagocytic-like NAD(P)H oxidase producing reactive oxygen species serves as a primary sensor for oxygen. We have characterized a source of superoxide anions in the kidney that we refer to as a renal NAD(P)H oxidase or Renox. Renox is homologous to gp91phox (91-kDa subunit of the phagocyte oxidase), the electron-transporting subunit of phagocytic NADPH oxidase, and contains all of the structural motifs considered essential for binding of heme, flavin, and nucleotide. In situ RNA hybridization revealed that renox is highly expressed at the site of erythropoietin production in the renal cortex, showing the greatest accumulation of renox mRNA in proximal convoluted tubule epithelial cells. NIH 3T3 fibroblasts overexpressing transfected Renox show increased production of superoxide and develop signs of cellular senescence. Our data suggest that Renox, as a renal source of reactive oxygen species, is a likely candidate for the oxygen sensor function regulating oxygen-dependent gene expression and may also have a role in the development of inflammatory processes in the kidney.