Selectively decreased expression of peroxiredoxins induced by silica in pulmonary epithelial cells.
OBJECTIVE
Peroxiredoxin (Prx) belongs to a ubiquitous family of antioxidant enzymes that regulates many cellular processes through intracellular oxidative signal transduction pathways. Silica-induced lung damage involves reactive oxygen species (ROS) that trigger subsequent toxic effects and inflammatory responses in alveolar epithelial cells resulting in fibrosis. Therefore, we investigated the role of Prx in the development of lung oxidant injury caused by silicosis, and determined the implication of ROS in that process.


METHODS
Lung epithelial cell lines A549 and WI26 were treated with 1% silica for 0, 24, or 48 hours, following pretreatment of the A549 cells with N-acetyl-L-cysteine and diphenylene iodonium and no pretreatment of the WI26 cells. We transfected an HA-ubiquitin construct into the A549 cell line and then analyzed the cells via Western blotting and co-immunoprecipitation.


RESULTS
Silica treatment induced cell death in the A549 lung epithelial cell line and selectively degraded Prx I without impairing protein synthesis in the A549 cells, even when the ROS effect was blocked chemically by N-acetyl-L-cysteine. A co-immunoprecipitation study revealed that Prx I did not undergo ubiquitination.


CONCLUSIONS
Silica treatment induces a decrease of Prx I expression in lung epithelial cell lines regardless of the presence of ROS. The silica-induced degradation of Prx does not involve the ubiquitin-proteasomal pathway.
Lee
Hye Lim
HL
Department of Pulmonary and Critical Care Medicine, Ajou University School of Medicine, Suwon, Korea.
Kim
Young Sun
YS
Park
Joo Hun
JH
Chung
Wou Young
WY
Lee
Kyu Sung
KS
Oh
Yoon Jung
YJ
Sheen
Seung Soo
SS
Park
Kwang Joo
KJ
Hwang
Sung Chul
SC
D002460:Cell Line; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D008168:Lung / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D054464:Peroxiredoxins / Q000032:analysis / Q000502:physiology*; D020033:Protein Isoforms; D017382:Reactive Oxygen Species / Q000378:metabolism; D012822:Silicon Dioxide / Q000633:toxicity*; D025801:Ubiquitin / Q000378:metabolism
D020033:Protein Isoforms; D017382:Reactive Oxygen Species; D025801:Ubiquitin; D012822:Silicon Dioxide; C515940:PRDX1 protein, human; D054464:Peroxiredoxins