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,pp.20-9
著者・共著者	MIYAYAMA Takamitsu†*, ARAI Yuta, HIRANO Seishiro
担当区分	筆頭著者,責任著者
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