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This Article Full Text Full Text (PDF) All Versions of this Article: 291/2/L272    most recent 00342.2005v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Turi, J. L. Articles by Ghio, A. J. Search for Related Content PubMed PubMed Citation Articles by Turi, J. L. Articles by Ghio, A. J.

Duodenal cytochrome b: a novel ferrireductase in airway epithelial cells

Departments of ¹Pediatrics and ⁵Medicine, Duke University Medical Center, Durham; ²National Health and Environmental Effects Research Laboratory, Environmental Protection Agency, Research Triangle Park, North Carolina; ³Department of Molecular Medicine, Guy's, King's, and St. Thomas' School of Medicine, King's College London, London, United Kingdom; and ⁴Department of Pediatrics, University of Colorado Health Sciences Center, Denver, Colorado

Submitted 4 August 2005 ; accepted in final form 24 February 2006

Catalytically active iron in the lung causes oxidative stress and promotes microbial growth that can be limited by intracellular sequestration of iron within ferritin. Because cellular iron uptake requires membrane ferrireductase activity that in the gut can be provided by duodenal cytochrome b (Dcytb), we sought Dcytb in the lung to test the hypothesis that it contributes to epithelial iron regulation by reducing Fe³⁺ for cellular iron transport. Dcytb expression was found in respiratory epithelium in vitro and in vivo and was responsive to iron concentration. Iron transport was measured in human bronchial epithelial (HBE) cells using inductively coupled plasma atomic emission spectroscopy and was demonstrated to be partially inhibited in the presence of Dcytb-blocking antibody, suggesting that Dcytb reduces Fe³⁺ for cellular iron transport. A definite source of reducing equivalents for Dcytb was sought but not identified. We found no evidence that ascorbate was involved but did demonstrate that O₂^–· production decreased when Dcytb function was blocked. The presence of Dcytb in airway epithelial cells and its regulation by iron therefore may contribute to pulmonary cytoprotection.

iron