title: Selectively decreased expression of peroxiredoxins induced by silica in pulmonary epithelial cells.
abstract: 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.
authors.affiliation: Department of Pulmonary and Critical Care Medicine, Ajou University School of Medicine, Suwon, Korea.
authors.forename: Hye Lim
authors.initials: HL
authors.lastname: Lee
authors.forename: Young Sun
authors.initials: YS
authors.lastname: Kim
authors.forename: Joo Hun
authors.initials: JH
authors.lastname: Park
authors.forename: Wou Young
authors.initials: WY
authors.lastname: Chung
authors.forename: Kyu Sung
authors.initials: KS
authors.lastname: Lee
authors.forename: Yoon Jung
authors.initials: YJ
authors.lastname: Oh
authors.forename: Seung Soo
authors.initials: SS
authors.lastname: Sheen
authors.forename: Kwang Joo
authors.initials: KJ
authors.lastname: Park
authors.forename: Sung Chul
authors.initials: SC
authors.lastname: Hwang
mesh_terms: 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
chemical_list: D020033:Protein Isoforms; D017382:Reactive Oxygen Species; D025801:Ubiquitin; D012822:Silicon Dioxide; C515940:PRDX1 protein, human; D054464:Peroxiredoxins