Requirement for Reactive Oxygen Species in Serum-induced and Platelet-derived Growth Factor-induced Growth of Airway Smooth Muscle

Abstract

Reactive oxygen species have been recently identified as important mediators of mitogenic signaling in a number of cell types. We therefore explored their role in mediating mitogenesis of airway smooth muscle. The antioxidants catalase, N-acetylcysteine, and probucol significantly reduced proliferation in primary cultures of rat tracheal smooth muscle stimulated with fetal bovine serum or platelet-derived growth factor, without affecting cell viability or inducing apoptosis. N-Acetylcysteine also significantly reduced serum-stimulated elevation of c-Fos but did not prevent the normal mitogeninduced increase in c-fos mRNA. Fractionation of ribosomes by sucrose density centrifugation and subsequent dot-blot Northern analysis revealed that antioxidants reduced incorporation of c-fos mRNA into the heaviest polyribosomes, suggesting redox regulation of c-fos mRNA translation. Serum treatment of monolayers produced a small but reproducibly significant rise in superoxide dismutase-inhibitable reduction of ferricytochrome c by myocyte monolayers. Serum-induced ferricytochrome c reduction, cellular proliferation, and c-Fos elevation were decreased by the flavoprotein-dependent enzyme inhibitor dipheyleneiodonium. Growth responses to fetal bovine serum and superoxide dismutase-inhibitable reduction of ferricytochrome c were not different between cultured tracheal myocytes from wild-type versus gp91 phagocyte oxidase null mice. These results suggest that mitogen stimulation of airway smooth muscle induces signal transduction of cell proliferation that is in part dependent on generation of partially reduced oxygen species, generated by an NADH or NADPH oxidoreductase that is different from the oxidase in phagocytic cells.

Non-hypoxic pathway mediates the induction of hypoxia inducible factor 1 alpha (HIF-1 alpha ) in vascular smooth muscle cells

“…The flavoproteincontaining enzyme inhibitor Diphenyleneiodonium (DPI) has been widely used to evaluate the activity of this pathway. DPI has been shown to inhibit Ang II, thrombin and PDGF mediated induction of ROS production in VSMC (31,34,35). When cells were pretreated with 10 µM DPI prior to stimulation with Ang II, HIF-1α induction was completely inhibited (Fig.…”

“…Recent evidence has convincingly shown that in VSMC, Ang II, thrombin and PDGF can modulate the expression and activity of different elements of the NAD(P)H oxidase system (32)(33)(34)(35)(36). This system is responsible for strong increases in intracellular ROS levels found in these cells after growth factor and hormone stimulation.…”

“…Different hormones and growth factors have been shown to activate the production of ROS in VSMC cells (31,34,35). It is interesting to note that VSMC cells specifically contain homologues to the various proteins that are similar to components of the phagocytic NAD(P)H oxidase whose activation leads to the production of ROS (32)(33)(34)(35)(36).…”

A redox cycle within the cell cycle: ring in the old with the new

“…Administering ROS activates a wide variety of proteins in various pathways; for example, platelet-derived growth factor (PDGF), EGF, mitogen-activated protein kinase (MAPK), protein kinase C (PKC) and protein kinase B (PKB/Akt) signal-transduction pathways. H 2 O 2 generation during the activation of PDGF, transforming growth factor and EGF receptor signaling has also been well established (Sundaresan et al, 1995;Bae et al, 1997;Brar et al, 1999;Junn et al, 2000;Okuyama et al, 2001). The H 2 O 2 generated results in tyrosine phosphorylation of the receptor, which subsequently activates MAPK (Gamou and Shimizu, 1995).…”

Airway smooth muscle cells: contributing to and regulating airway mucosal inflammation?

“…Nitric oxide can inhibit deoxyribonucleic acid (DNA) synthesis and the proliferation of airway smooth muscle. Reactive oxygen species generated by an oxidoreductase of reduced nicotinamide adenine dinucleotide are required for serum or PDGF-induced growth of airway smooth muscle cells [56]. Furthermore, superoxide dismutase mimetics are capable of inhibiting serum-induced proliferation of airway smooth muscle cells [55].…”