title: Oxidative stress upregulates zinc uptake activity via Zrt/Irt-like protein 1 (ZIP1) in cultured mouse astrocytes.
abstract: OBJECTIVE
  Zinc released from glutamatergic boutons and astrocytes acts as neuro- and glio-transmitters, and thus its extracellular level has to be strictly regulated. We previously revealed that uptake of zinc by astrocytes plays a critical role in its clearance, and zinc transporter Zrt/Irt-like protein 1 (ZIP1) is the molecule responsible for the uptake. However, it is unknown whether or not the functionality of the zinc clearance system is altered under oxidative stress-loaded conditions. Here, we characterized zinc uptake by oxidative stress-loaded astrocytes.
  
  
  METHODS
  Cultured mouse astrocytes were treated with hydrogen peroxide (H2O2) to load oxidative stress. Functional expression of ZIP1 in astrocytes was evaluated by means of (65)Zn uptake, Western blotting and immunocytochemical analysis.
  
  
  RESULTS
  Treatment of astrocytes with 0.4mM H2O2 for 24h increased the expression levels of glial fibrillary acidic protein and 4-hydroxynonenal without significant decreases in their viability, indicating that induction of oxidative stress in astrocytes. Under oxidative stress-loaded conditions, astrocytes exhibited increased (65)Zn uptake activity, and the maximum uptake velocity for the uptake was significantly increased compared to that in the control group, while there was no change in the Michaelis constants, which were almost identical to that of mouse ZIP1. In the H2O2-treated astrocytes, the expression levels of ZIP1 were significantly increased in the cellular and plasma membrane fractions.
  
  
  CONCLUSIONS
  It appears that under oxidative stress-loaded conditions, astrocytes exhibit increased zinc clearance activity and this is due, at least in part, to increased ZIP1 expression.
authors.affiliation: Department of Environmental Biochemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Furuta
authors.affiliation: Department of Environmental Biochemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan.
authors.forename: Chiaki
authors.initials: C
authors.lastname: Ohshima
authors.affiliation: Department of Environmental Biochemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan.
authors.forename: Mayu
authors.initials: M
authors.lastname: Matsumura
authors.affiliation: Department of Environmental Biochemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Takebayashi
authors.affiliation: Department of Environmental Biochemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan.
authors.forename: Emi
authors.initials: E
authors.lastname: Hirota
authors.affiliation: Department of Environmental Biochemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Mawaribuchi
authors.affiliation: Department of Environmental Biochemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Nishida
authors.affiliation: Department of Environmental Biochemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan. Electronic address: nagasawa@mb.kyoto-phu.ac.jp.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Nagasawa
mesh_terms: D000447:Aldehydes / Q000378:metabolism; D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000096:biosynthesis / Q000502:physiology*; D002470:Cell Survival; D005904:Glial Fibrillary Acidic Protein / Q000096:biosynthesis; D006861:Hydrogen Peroxide; D051379:Mice; D018384:Oxidative Stress / Q000502:physiology*; D061251:Primary Cell Culture; D015032:Zinc / Q000378:metabolism*
chemical_list: D000447:Aldehydes; D027682:Cation Transport Proteins; D005904:Glial Fibrillary Acidic Protein; C485744:Slc39a1 protein, mouse; D006861:Hydrogen Peroxide; D015032:Zinc; C027576:4-hydroxy-2-nonenal
keywords: Astrocyte; Oxidative stress; ZIP1; Zinc uptake