Tuberc Respir Dis.  2005 Mar;58(3):267-275. 10.4046/trd.2005.58.3.267.

Role of Reactive Oxygen Species in Transforming Growth Factor - beta1 - inuduced Fibronectin Secretion and alpha - Smooth Muscle Actin Expression in Human Lung Fibroblasts

Affiliations
  • 1Hyonam Kidney Laboratory, Soon Chun Hyang University, Korea. hblee@hkl.ac.kr
  • 2Ewha Womans University College of Pharmacy, Korea.
  • 3Department of Internal Medicine, Soon Chun Hyang University College of Medicine, Korea.

Abstract

BACKGROUND: The transforming growth factor-beta1 (TGF-beta1) plays a key role in lung fibrosis. However, the mole?cular mechanisms involved in TGF-beta1-induced lung fibrosis are unclear. TGF-beta1 is the key inducer of myofibroblast transdifferentiation via de novo synthesis of alphasmooth muscle actin (alpha-SMA). Since TGF-beta1 signals through reactive oxygen species (ROS) and ROS have been shown to induce accumulation of extracellular matrix (ECM) in various tissues, this study examined if ROS play a role in TGF-beta1-induced fibronectin secretion and alpha-SMA expression in human lung fibroblasts, MRC-5 cells.
METHODS
Growth arrested and synchronized MRC-5 cells were stimulated with TGF-beta1 (0.2-10 ng/ml) in the presence or absence of N-acetylcysteine (NAC) or diphenyleneiodonium (DPI) for up to 96 hours. Dichlorofluorescein (DCF)- sensitive cellular ROS were measured by FACScan and secreted fibronectin and cellular alpha-SMA by Western blot analysis.
RESULTS
TGF-beta1 increased the level of fibronectin secretion and alpha-SMA expression in MRC-5 cells in a dose- dependent manner. Both NAC (20 and 30 mM) and DPI (1 and 5 microM significantly inhibited TGF-beta1-induced fibronectin and alpha-SMA upregulation. The TGF-beta1-induced cellular ROS level was also significantly reduced by NAC and DPI.
CONCLUSIONS
The results suggest that NADPH oxidase-dependent ROS play an important role in TGF-beta1-induced fibronectin secretion and alpha-SMA expression in MRC-5 cells, which leads to myofibroblast transdifferentiation and progressive lung fibrosis.

Keyword

Pulmonary fibrosis; Transforming growth factor-beta1; Reactive oxygen species; alpha-Smooth muscle actin; Fibroblast; Myofibroblast; Fibronectin; N-acetylcysteine; Diphenyleneiodonium

MeSH Terms

Acetylcysteine
Actins*
Blotting, Western
Extracellular Matrix
Fibroblasts*
Fibronectins*
Fibrosis
Humans*
Lung*
Muscle, Smooth*
Myofibroblasts
NADP
Pulmonary Fibrosis
Reactive Oxygen Species*
Transforming Growth Factor beta1
Transforming Growth Factors*
Up-Regulation
Acetylcysteine
Actins
Fibronectins
NADP
Reactive Oxygen Species
Transforming Growth Factor beta1
Transforming Growth Factors
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