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Cellular low zinc levels increase cell oxidants partially through a mechanism involving NADPH oxidase
Author(s) -
AIMO LUCILA,
MACKENZIE GERARDO,
OTEIZA PATRICIA
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a995-b
Subject(s) - nadph oxidase , reactive oxygen species , transactivation , chemistry , zinc , oxidase test , incubation , microbiology and biotechnology , biochemistry , transcription factor , enzyme , biology , gene , organic chemistry
Several studies have shown that a condition of zinc (Zn) deficiency increases the production of cell oxidants such as reactive oxygen species (ROS), reactive nitrogen species and carbon‐centered free radicals. However, the mechanisms involved in the high levels of cellular ROS are still unclear. The objective of this study was to test the hypothesis that a decrease in cellular Zn levels can lead to an increased ROS production through a mechanism that involves NADPH oxidase. For this purpose, human IMR‐32 neuroblastoma cells were cultured in control (C) or Zn‐chelated media containing 1.5 (1.5 Zn) or 15 μM (15 Zn) Zn. Global cell oxidants, measured with DCDCDHF, H 2 O 2 production, measured with Amplex Red, and the activation of the H 2 O 2 ‐responsive transcription factor AP‐1 were determined. After 2 to 6 h of incubation, significantly higher levels of oxidants (DCDCDHF) were found in the 1.5 Zn (60–40 %, p < 0.005) compared to C and 15 Zn cells. This increase was reduced (p < 0.001) when cells were incubated simultaneously in the presence of NADPH oxidase inhibitor DPI. Similar results were observed when H 2 O 2 was determined. We next evaluated the effect of Zn deficiency‐induced increase in H 2 O 2 on the activation of AP‐1. A significant increase in AP‐1‐DNA binding activity (40%) and in the transactivation of an AP‐1‐driven gene (p‐AP1‐Luc) (60%) of the Zn deficient cells was observed after 2 and 6 h respectively. Results indicate that Zn deficiency could increase ROS production and trigger oxidant‐responsive cell signals partially through a mechanism involving NADPH oxidase. Supported by grants from the University of California and NIEHS‐CEHS, USA