Silica-induced generation of reactive oxygen species in Rat2 fibroblast: role in activation of mitogen-activated protein kinase.
Exposure to silica has been associated with progressive pulmonary inflammation and fibrosis. While the fibroblasts play an important role in the pathogenesis of silicosis, the direct interaction between silica and fibroblasts is poorly understood. We observed that silica particles stimulated intracellular ROS generation in Rat2 fibroblast, evidenced by DCFH oxidation. Silica-induced DCFH oxidation was inhibited by catalase and DPI, a flavoenzyme inhibitor. Additionally, the time course of elevation of the intracellular ROS was paralleled by the increases of MEK and ERK phosphorylation. Silica-induced ERK phosphorylation was also effectively attenuated by catalase and DPI. However, SOD enhanced the silica-induced ERK phosphorylation, indicating a role for H(2)O(2) in ERK activation. Furthermore, ERK and MEK phosphorylation are reproduced by H(2)O(2) treatment. Taken together, these results demonstrate that silica stimulates ROS production via flavoenzyme-dependent mechanism in Rat2 fibroblasts and the H(2)O(2), in turn, serves as a signal transduction element in activating MEK-ERK pathway.
Cho
Y J
YJ
Department of Pharmacology, Catholic University of Korea, Seoul, 137-701, Korea.
Seo
M S
MS
Kim
J K
JK
Lim
Y
Y
Chae
G
G
Ha
K S
KS
Lee
K H
KH
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002374:Catalase / Q000494:pharmacology; D002460:Cell Line; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000493:pharmacokinetics; D005347:Fibroblasts; D006861:Hydrogen Peroxide / Q000378:metabolism; D009861:Onium Compounds / Q000493:pharmacokinetics; D010084:Oxidation-Reduction; D010766:Phosphorylation; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D012822:Silicon Dioxide / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D009861:Onium Compounds; D017382:Reactive Oxygen Species; C007517:diphenyleneiodonium; D012822:Silicon Dioxide; D006861:Hydrogen Peroxide; D002374:Catalase; D017871:Calcium-Calmodulin-Dependent Protein Kinases