BioMetals

, Volume 22, Issue 5, pp 803–815

Zinc transport by respiratory epithelial cells and interaction with iron homeostasis

  • Zhongping Deng
  • Lisa A. Dailey
  • Joleen Soukup
  • Jacqueline Stonehuerner
  • Judy D. Richards
  • Kimberly D. Callaghan
  • Funmei Yang
  • Andrew J. Ghio
Article

DOI: 10.1007/s10534-009-9227-2

Cite this article as:
Deng, Z., Dailey, L.A., Soukup, J. et al. Biometals (2009) 22: 803. doi:10.1007/s10534-009-9227-2

Abstract

Despite recurrent exposure to zinc through inhalation of ambient air pollution particles, relatively little information is known about the homeostasis of this metal in respiratory epithelial cells. We describe zinc uptake and release by respiratory epithelial cells and test the postulate that Zn2+ transport interacts with iron homeostasis in these same cells. Zn2+ uptake after 4 and 8 h of exposure to zinc sulfate was concentration- and time-dependent. A majority of Zn2+ release occurred in the 4 h immediately following cell exposure to ZnSO4. Regarding metal importers, mRNA for Zip1 and Zip2 showed no change after respiratory epithelial cell exposure to zinc while mRNA for divalent metal transporter (DMT)1 increased. Western blot assay for DMT1 protein supported an elevated expression of this transport protein following zinc exposure. RT-PCR confirmed mRNA for the metal exporters ZnT1 and ZnT4 with the former increasing after ZnSO4. Cell concentrations of ferritin increased with zinc exposure while oxidative stress, measured as lipid peroxides, was decreased supporting an anti-oxidant function for Zn2+. Increased DMT1 expression, following pre-incubations of respiratory epithelial cells with TNF-α, IFN-γ, and endotoxin, was associated with significantly decreased intracellular zinc transport. Finally, incubations of respiratory epithelial cells with both zinc sulfate and ferric ammonium citrate resulted in elevated intracellular concentrations of both metals. We conclude that exposure to zinc increases iron uptake by respiratory epithelial cells. Elevations in cell iron can possibly affect an increased expression of DMT1 and ferritin which function to diminish oxidative stress. Comparable to other metal exposures, changes in iron homeostasis may contribute to the biological effects of zinc in specific cells and tissues.

Keywords

Zinc compounds Iron Oxidative stress Divalent metal transporter 1 Ferritin Membrane transporters Metals Lung 

Abbreviations

DMSO

Dimethylsulfoxide

DMT1

Divalent metal transporter 1

DNPH

2,4-Dinitrophenylhydrazine

DPBS

Dulbecco’s phosphate buffered saline

HBE

Human bronchial epithelial

ICPOES

Inductively coupled plasma optical emission spectroscopy

KGM

Keratinocyte growth medium

LDH

Lactate dehydrogenase

MTT

Methylthiazoletetrazolium

PM

Particulate matter

TCA

Trichloroacetic acid

Tf

Transferrin

TfR

Transferrin receptor

Copyright information

© Springer Science+Business Media, LLC. 2009

Authors and Affiliations

  • Zhongping Deng
    • 1
    • 2
  • Lisa A. Dailey
    • 3
  • Joleen Soukup
    • 3
  • Jacqueline Stonehuerner
    • 3
  • Judy D. Richards
    • 3
  • Kimberly D. Callaghan
    • 4
  • Funmei Yang
    • 4
  • Andrew J. Ghio
    • 3
    • 5
  1. 1.Center for Environmental Medicine, Asthma and Lung BiologyUniversity of North CarolinaChapel HillUSA
  2. 2.National Shanghai Center for Drug Safety Evaluation and ResearchShanghai Institute of Pharmaceutical IndustryShanghaiChina
  3. 3.National Health and Environmental Effects Research Laboratory, Office of Research and DevelopmentUnited States Environmental Protection AgencyDurhamUSA
  4. 4.Department of Cellular and Structural BiologyUniversity of Texas Health Science CenterSan AntonioUSA
  5. 5.Human Studies Division, US EPAChapel HillUSA

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