title: Activation of hypoxia-inducible factor-1 protects airway epithelium against oxidant-induced barrier dysfunction.
abstract: The respiratory epithelium forms an important barrier against inhaled pollutants and microorganisms, and its barrier function is often compromised during inflammatory airway diseases. Epithelial activation of hypoxia-inducible factor-1 (HIF-1) represents one feature of airway inflammation, but the functional importance of HIF-1 within the respiratory epithelium is largely unknown. Using primary mouse tracheal epithelial (MTE) cells or immortalized human bronchial epithelial cells (16HBE14o-), we evaluated the impact of HIF-1 activation on loss of epithelial barrier function during oxidative stress. Exposure of either 16HBE14o- or MTE cells to H(2)O(2) resulted in significant loss of transepithelial electrical resistance and increased permeability to fluorescein isothiocyanate-dextran (4 kDa), and this was attenuated significantly after prior activation of HIF-1 by preexposure to hypoxia (2% O(2); 6 h) or the hypoxia mimics CoCl(2) or dimethyloxalylglycine (DMOG). Oxidative barrier loss was associated with reduced levels of the tight junction protein occludin and with hyperoxidation of the antioxidant enzyme peroxiredoxin (Prx-SO(2)H), events that were also attenuated by prior activation of HIF-1. Involvement of HIF-1 in these protective effects was confirmed using the pharmacological inhibitor YC-1 and by short-hairpin RNA knockdown of HIF-1α. The protective effects of HIF-1 were associated with induction of sestrin-2, a hypoxia-inducible enzyme known to reduce oxidative stress and minimize Prx hyperoxidation. Together, our results suggest that loss of epithelial barrier integrity by oxidative stress is minimized by activation of HIF-1, in part by induction of sestrin-2.
authors.affiliation: Department of Pathology, College of Medicine, University of Vermont, Burlington, 05405-0068, USA.
authors.forename: Nels
authors.initials: N
authors.lastname: Olson
authors.forename: Milena
authors.initials: M
authors.lastname: Hristova
authors.forename: Nicholas H
authors.initials: NH
authors.lastname: Heintz
authors.forename: Karen M
authors.initials: KM
authors.lastname: Lounsbury
authors.forename: Albert
authors.initials: A
authors.lastname: van der Vliet
mesh_terms: D000600:Amino Acids, Dicarboxylic / Q000494:pharmacology; D000818:Animals; D015687:Cell Hypoxia; D002460:Cell Line; D003035:Cobalt / Q000494:pharmacology; D003911:Dextrans / Q000493:pharmacokinetics; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D005456:Fluorescent Dyes / Q000493:pharmacokinetics; D055785:Gene Knockdown Techniques; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009687:Nuclear Proteins / Q000378:metabolism; D062793:Occludin; D016877:Oxidants / Q000494:pharmacology*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010539:Permeability; D054464:Peroxiredoxins / Q000378:metabolism; D061251:Primary Cell Culture; D011393:Procollagen-Proline Dioxygenase / Q000037:antagonists & inhibitors; D034622:RNA Interference; D020545:Respiratory Mucosa / Q000378:metabolism / Q000473:pathology*; D014132:Trachea / Q000473:pathology; D000084622:Sestrins
chemical_list: D000600:Amino Acids, Dicarboxylic; D003035:Cobalt; D003911:Dextrans; D016650:Fluorescein-5-isothiocyanate; D005456:Fluorescent Dyes; D006861:Hydrogen Peroxide; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008565:Membrane Proteins; D009687:Nuclear Proteins; D062793:Occludin; D016877:Oxidants; D054464:Peroxiredoxins; D011393:Procollagen-Proline Dioxygenase; C568985:OCLN protein, human; C568986:Ocln protein, mouse; C465398:SESN2 protein, human; D000084622:Sestrins; C015219:fluorescein isothiocyanate dextran; C018021:cobaltous chloride; C040947:oxalylglycine