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P1‐201: Hypoxia regulates the ferrous iron uptake and reactive oxygen species (ROS) level via divalent metal transporter 1 (DMT1) by hypoxia‐inducible factor‐1
Author(s) -
Wang Dan,
Wang Lihong,
Zhu Li
Publication year - 2010
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2010.05.752
Subject(s) - dmt1 , reactive oxygen species , transferrin , transcription factor , ferrous , chemistry , hypoxia (environmental) , western blot , biology , microbiology and biotechnology , transporter , biochemistry , oxygen , gene , organic chemistry
Background: Recent studies have shown that bivalent metals such as iron, copper, and zinc are involved in APP expression, Ab deposition, and senile plaque formation in the AD brain. The divalent metal transporter 1 (DMT1) plays a critical role in ion-mediated neuropathogenesis in AD and that pharmacological blockage of DMT1 may provide novel therapeutic strategies against AD. DMT1 is a protein recently shown to play a pivotal role in iron uptake from both transferrin (Tf) and non-Tf sources in different anatomic sites. Iron is needed for several essential functions including cellular growth and survival but is also potentially dangerous as a catalyst of reactive oxygen species production, so it is toxic when present in excess. In mammalian cells, exposure to a low-oxygen environment triggers a hypoxic response pathway centered on the regulated expression of the hypoxia-inducible transcription factor (HIF). Hypoxia has been shown to increase the expression of a variety of proteins involved in iron homeostasis. Although previous studies have provided expression of DMT1 increased by hypoxia, little is known about the relationship between DMT1 and hypoxia. Methods: Cells were exposed hypoxia (1%O2). The expression of DMT1 and HIF-1a were detected by Western Blot. The coding sequence of HIF-1a was constructed into expressed vector called pcDNA3-HIF-1a. DNA fragments from the DMT1 promoter region were cloned into the luciferase reporter vectors. The luciferase activity was quantitated to identify the relationship between HIF-1a and transcription of DMT1. Atomicabsorption spectroscopy and Calcein loading were used to quantify the total amount of iron or ferrous iron uptake, respectively. Results: In this study we have identified a functional hypoxia response element (HRE) that contains a binding site for hypoxia-inducible factor-1 (HIF-1). Here we have identified a founctional HRE at position of -327 w -323 (ACGTG) in DMT1 promoter. Both the total cellular iron and ferrous uptake increased after hypoxia, decreased after RNA interference DMT1. Reactive oxygen species (ROS) were also increased by DMT1. Conclusions: DMT1 is a target gene for HIF-1 and hypoxia might affect cellular iron uptake and ROS through regulating the expression of DMT1.