Ras-dependent and -independent regulation of reactive oxygen species by mitogenic growth factors and TGF-beta1.
Mitogenic growth factors and transforming growth factor beta1 (TGF-beta1) induce the generation of reactive oxygen species (ROS) in nonphagocytic cells, but their enzymatic source(s) and regulatory mechanisms are largely unknown. We previously reported on the ability of TGF-beta1 to activate a cell surface-associated NADH:flavin:O(2) oxidoreductase (NADH oxidase) that generates extracellular H(2)O(2). In this study, we compared the ROS-generating enzymatic systems activated by mitogenic growth factors and TGF-beta1 with respect to the primary reactive species produced (O(2)(.-) vs. H(2)O(2)), the site of generation (intracellular vs. extracellular) and regulation by Ras. We find that the mitogenic growth factors PDGF-BB, FGF-2, and TGF-alpha (an EGF receptor ligand) are able to rapidly (within 5 min) induce the generation of intracellular O(2)(.-) without detectable NADH oxidase activity or extracellular H(2)O(2) release. In contrast, TGF-beta1 does not stimulate intracellular O(2)(.-) production and the delayed induction of extracellular H(2)O(2) release is not associated with O(2)(.-) production. Expression of dominant-negative Ras (N17Ras) protein by herpes simplex virus-mediated gene transfer blocks mitogen-stimulated intracellular O(2)(.-) generation but has no effect on TGF-beta1-induced NADH oxidase activation/H(2)O(2) production. These results demonstrate that there are at least two distinctly different ROS-generating enzymatic systems in lung fibroblasts regulated by mitogenic growth factors and TGF-beta1 via Ras-dependent and -independent mechanisms, respectively. In addition, these findings suggest that endogenous production of ROS by growth factors/cytokines may have different biological effects depending on the primary reactive species generated and site of production.
Thannickal
V J
VJ
Pulmonary and Critical Care Division, Department of Medicine, New England Medical Center/Tupper Research Institute. Department of Biochemistry, Tufts University School of Medicine, Boston, Massachusetts 02111, USA. vthannickal@lifespan.org
Day
R M
RM
Klinz
S G
SG
Bastien
M C
MC
Larios
J M
JM
Fanburg
B L
BL
D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D008168:Lung / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D009097:Multienzyme Complexes / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D008249:Protein-Lysine 6-Oxidase / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction; D015320:Tachykinins; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D018631:ras Proteins / Q000378:metabolism*
D009097:Multienzyme Complexes; D017382:Reactive Oxygen Species; D015320:Tachykinins; D016212:Transforming Growth Factor beta; D016222:Fibroblast Growth Factor 2; C083384:ranatachykinin A; D006861:Hydrogen Peroxide; D008249:Protein-Lysine 6-Oxidase; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases; D018631:ras Proteins