title: Ctr1 transports silver into mammalian cells.
abstract: Silver is a non-essential, toxic metal. The use of silver as an antimicrobial agent in many applications and its presence as a contaminant in foods and air can lead to accumulation in tissues. Despite its widespread use, the systems involved in the uptake of silver into mammalian cells are presently unknown. Previous studies have shown that copper uptake at the plasma membrane by copper transporter 1 (Ctr1) is inhibited by an excess of silver, suggesting that Ctr1 may function in importing silver into cells. In this study we examined directly the role of Ctr1 in the accumulation of silver in mammalian cells using over-expression experiments and mouse embryonic fibroblast cells lacking Ctr1. COS-7 cells transfected to express a human Ctr1-green fluorescent protein (hCtr1-GFP) fusion protein hyper-accumulated silver when incubated in medium supplemented with low micromolar concentrations (2.5-10 micromol/L) of AgNO(3). An hCtr1-GFPM150L,M154L variant deficient for copper transport failed to stimulate accumulation of silver. Mouse embryonic fibroblast cells lacking Ctr1 showed approximately a 50% reduction in silver content when incubated in silver-supplemented medium compared to a wild-type isogenic cell line. Collectively, these data demonstrate that Ctr1 transports both copper and silver and suggest that Ctr1 is an important transport protein in the accumulation of silver in mammalian cells.
authors.affiliation: Nutrition Research Division, Health Products and Food Branch, Health Canada, Ottawa, Ontario, Canada. jesse_bertinato@hc-sc.gc.ca
authors.forename: Jesse
authors.initials: J
authors.lastname: Bertinato
authors.forename: Lawrence
authors.initials: L
authors.lastname: Cheung
authors.forename: Rezaul
authors.initials: R
authors.lastname: Hoque
authors.forename: Louise J
authors.initials: LJ
authors.lastname: Plouffe
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D019556:COS Cells; D027682:Cation Transport Proteins / Q000172:deficiency / Q000378:metabolism*; D002522:Chlorocebus aethiops; D003300:Copper / Q000378:metabolism; D000079923:Copper Transporter 1; D004622:Embryo, Mammalian / Q000166:cytology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012834:Silver / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D027682:Cation Transport Proteins; D000079923:Copper Transporter 1; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D012834:Silver; D003300:Copper