title: Rapid disruption of intestinal epithelial tight junction and barrier dysfunction by ionizing radiation in mouse colon in vivo: protection by N-acetyl-l-cysteine.
abstract: The goals of this study were to evaluate the effects of ionizing radiation on apical junctions in colonic epithelium and mucosal barrier function in mice in vivo. Adult mice were subjected to total body irradiation (4 Gy) with or without N-acetyl-l-cysteine (NAC) feeding for 5 days before irradiation. At 2-24 h postirradiation, the integrity of colonic epithelial tight junctions (TJ), adherens junctions (AJ), and the actin cytoskeleton was assessed by immunofluorescence microscopy and immunoblot analysis of detergent-insoluble fractions for TJ and AJ proteins. The barrier function was evaluated by measuring vascular-to-luminal flux of fluorescein isothiocyanate (FITC)-inulin in vivo and luminal-to-mucosal flux in vitro. Oxidative stress was evaluated by measuring protein thiol oxidation. Confocal microscopy showed that radiation caused redistribution of occludin, zona occludens-1, claudin-3, E-cadherin, and β-catenin, as well as the actin cytoskeleton as early as 2 h postirradiation, and this effect was sustained for at least 24 h. Feeding NAC before irradiation blocked radiation-induced disruption of TJ, AJ, and the actin cytoskeleton. Radiation increased mucosal permeability to inulin in colon, which was blocked by NAC feeding. The level of reduced-protein thiols in colon was depleted by radiation with a concomitant increase in the level of oxidized-protein thiol. NAC feeding blocked the radiation-induced protein thiol oxidation. These data demonstrate that radiation rapidly disrupts TJ, AJ, and the actin cytoskeleton by an oxidative stress-dependent mechanism that can be prevented by NAC feeding.
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee.
authors.forename: Pradeep K
authors.initials: PK
authors.lastname: Shukla
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee.
authors.forename: Ruchika
authors.initials: R
authors.lastname: Gangwar
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee.
authors.forename: Bhargavi
authors.initials: B
authors.lastname: Manda
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee.
authors.forename: Avtar S
authors.initials: AS
authors.lastname: Meena
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee.
authors.forename: Nikki
authors.initials: N
authors.lastname: Yadav
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee.
authors.forename: Erzsebet
authors.initials: E
authors.lastname: Szabo
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee.
authors.forename: Andrea
authors.initials: A
authors.lastname: Balogh
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee.
authors.forename: Sue Chin
authors.initials: SC
authors.lastname: Lee
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee.
authors.forename: Gabor
authors.initials: G
authors.lastname: Tigyi
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee rrao2@uthsc.edu.
authors.forename: RadhaKrishna
authors.initials: R
authors.lastname: Rao
mesh_terms: D000111:Acetylcysteine / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D008841:Actin Cytoskeleton / Q000378:metabolism; D000818:Animals; D003106:Colon / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D019587:Dietary Supplements; D005260:Female; D016166:Free Radical Scavengers / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D007444:Inulin / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018384:Oxidative Stress; D011832:Radiation Injuries / Q000188:drug therapy / Q000517:prevention & control*; D011839:Radiation, Ionizing; D011837:Radiation-Protective Agents / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D013438:Sulfhydryl Compounds / Q000378:metabolism; D062725:Tight Junction Proteins / Q000378:metabolism; D019108:Tight Junctions / Q000378:metabolism / Q000528:radiation effects*
chemical_list: D016166:Free Radical Scavengers; D011837:Radiation-Protective Agents; D013438:Sulfhydryl Compounds; D062725:Tight Junction Proteins; D007444:Inulin; D000111:Acetylcysteine
keywords: actin; adherens junction; barrier function; cytoskeleton; intestine; occludin; oxidative stress; protein thiol; zona occludens-1
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