title: Calcium Channels and Oxidative Stress Mediate a Synergistic Disruption of Tight Junctions by Ethanol and Acetaldehyde in Caco-2 Cell Monolayers.
abstract: Ethanol is metabolized into acetaldehyde in most tissues. In this study, we investigated the synergistic effect of ethanol and acetaldehyde on the tight junction integrity in Caco-2 cell monolayers. Expression of alcohol dehydrogenase sensitized Caco-2 cells to ethanol-induced tight junction disruption and barrier dysfunction, whereas aldehyde dehydrogenase attenuated acetaldehyde-induced tight junction disruption. Ethanol up to 150 mM did not affect tight junction integrity or barrier function, but it dose-dependently increased acetaldehyde-mediated tight junction disruption and barrier dysfunction. Src kinase and MLCK inhibitors blocked this synergistic effect of ethanol and acetaldehyde on tight junction. Ethanol and acetaldehyde caused a rapid and synergistic elevation of intracellular calcium. Calcium depletion by BAPTA or Ca2+-free medium blocked ethanol and acetaldehyde-induced barrier dysfunction and tight junction disruption. Diltiazem and selective knockdown of TRPV6 or CaV1.3 channels, by shRNA blocked ethanol and acetaldehyde-induced tight junction disruption and barrier dysfunction. Ethanol and acetaldehyde induced a rapid and synergistic increase in reactive oxygen species by a calcium-dependent mechanism. N-acetyl-L-cysteine and cyclosporine A, blocked ethanol and acetaldehyde-induced barrier dysfunction and tight junction disruption. These results demonstrate that ethanol and acetaldehyde synergistically disrupt tight junctions by a mechanism involving calcium, oxidative stress, Src kinase and MLCK.
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, 894 Union Avenue, Memphis TN 38163, USA.
authors.forename: Geetha
authors.initials: G
authors.lastname: Samak
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, 894 Union Avenue, Memphis TN 38163, USA.
authors.forename: Ruchika
authors.initials: R
authors.lastname: Gangwar
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, 894 Union Avenue, Memphis TN 38163, USA.
authors.forename: Avtar S
authors.initials: AS
authors.lastname: Meena
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, 894 Union Avenue, Memphis TN 38163, USA.
authors.forename: Roshan G
authors.initials: RG
authors.lastname: Rao
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, 894 Union Avenue, Memphis TN 38163, USA.
authors.forename: Pradeep K
authors.initials: PK
authors.lastname: Shukla
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, 894 Union Avenue, Memphis TN 38163, USA.
authors.forename: Bhargavi
authors.initials: B
authors.lastname: Manda
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, 894 Union Avenue, Memphis TN 38163, USA.
authors.forename: Damodaran
authors.initials: D
authors.lastname: Narayanan
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, 894 Union Avenue, Memphis TN 38163, USA.
authors.forename: Jonathan H
authors.initials: JH
authors.lastname: Jaggar
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, 894 Union Avenue, Memphis TN 38163, USA.
authors.forename: RadhaKrishna
authors.initials: R
authors.lastname: Rao
mesh_terms: D000079:Acetaldehyde / Q000378:metabolism* / Q000494:pharmacology; D000426:Alcohol Dehydrogenase / Q000378:metabolism; D000071396:Aldehyde Dehydrogenase, Mitochondrial / Q000378:metabolism; D018938:Caco-2 Cells; D015220:Calcium Channels / Q000378:metabolism*; D002478:Cells, Cultured; D000431:Ethanol / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D018384:Oxidative Stress / Q000187:drug effects*; D019108:Tight Junctions / Q000187:drug effects* / Q000378:metabolism*; D062826:Zonula Occludens-1 Protein / Q000378:metabolism
chemical_list: D015220:Calcium Channels; C569042:TJP1 protein, human; D062826:Zonula Occludens-1 Protein; D000431:Ethanol; C489332:ADH1B protein, human; D000426:Alcohol Dehydrogenase; C096127:ALDH2 protein, human; D000071396:Aldehyde Dehydrogenase, Mitochondrial; D000079:Acetaldehyde