ミヤヤマ タカミツ   Takamitsu Miyayama
  宮山 貴光
   所属   医学部 医学科
   職種   助教
論文種別 原著
言語種別 英語
査読の有無 査読あり
表題 Mitochondrial electron transport is inhibited by disappearance of metallothionein in human bronchial epithelial cells following exposure to silver nitrate
掲載誌名 正式名:Toxicology
ISSNコード:1879-3185 (Electronic)0300-483X (Linking)
巻・号・頁 305,20-9頁
著者・共著者 MIYAYAMA Takamitsu†*, ARAI Yuta, HIRANO Seishiro
発行年月 2013/03
概要 Silver (Ag) possesses antibacterial activity and has been used in wound dressings and deodorant powders worldwide. However, the metabolic behavior and biological roles of Ag in mammals have not been well characterized. In the present study, we exposed human bronchial epithelial cells (BEAS-2B) to AgNO3 and investigated uptake and intracellular distribution of Ag, expression of metallothionein (MT), generation of reactive oxygen species (ROS), and changes in mitochondrial respiration. The culture medium concentration of Ag decreased with time and stabilized at 12h. The concentration of both Ag and MT in the soluble cellular fraction increased up to 3h and then decreased, indicating that cytosolic Ag relocated to the insoluble fraction of the cells. The levels of mRNAs for the major human MT isoforms MT-I and MT-II paralleled with the protein levels of Ag-MT. The intensity of fluorescence derived from ROS was elevated in the mitochondrial region at 24h. Ag decreased mitochondrial oxygen consumption in a dose-dependent manner and the activity of mitochondrial complex I-IV enzymes was significantly inhibited following exposure to Ag. In a separate experiment, we found that hydrogen peroxide (H2O2) at concentrations as low as 0.001% (equivalent to the concentration of H2O2 in Ag-exposed cells) removed Ag from MT. These results suggest MT was decomposed by cytosolic H2O2, and then Ag released from MT relocated to insoluble cellular fractions and inhibited electron chain transfer of mitochondrial complexes, which eventually led to cell damage.
DOI 10.1016/j.tox.2013.01.004S0300-483X(13)00009-7 [pii]
文献番号 23333424