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DUODENAL CYTOCHROME B: A NOVEL FERRIREDUCTASE IN AIRWAY EPITHELIAL CELLS
TURI, J., X. WANG, A. T. MCKIE, E. NOZIK-GRAYCK, L. B. MAMO, K. M. CRISSMAN, C. A. PIANTADOSI, AND A. J. GHIO. DUODENAL CYTOCHROME B: A NOVEL FERRIREDUCTASE IN AIRWAY EPITHELIAL CELLS. American Journal of Physiology - Lung Cellular and Molecular Physiology. American Physiological Society, Bethesda, MD, 291(2):L272-280, (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 Fe(3+) 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 Fe(3+) 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 O(2)(-). 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.
to test the hypothesis that duodenal cytochrome b contributes to epithelial iron regulation by reducing Fe(3+) for cellular iron transport
Record Details:Record Type: DOCUMENT (JOURNAL/PEER REVIEWED JOURNAL)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL HEALTH AND ENVIRONMENTAL EFFECTS RESEARCH LAB
HUMAN STUDIES DIVISION
CLINICAL RESEARCH BRANCH