Open AccessDysregulation of junctional adhesion molecule‐A contributes to ethanol‐induced barrier disruption in intestinal epithelial cell monolayers
Author(s) -
Chopyk Daniel M.,
Kumar Pradeep,
Raeman Reben,
Liu Yunshan,
Smith Tekla,
Anania Frank A.
Publication year - 2017
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.13541
Subject(s) - paracellular transport , tight junction , occludin , claudin , barrier function , microbiology and biotechnology , intestinal epithelium , chemistry , gene knockdown , caco 2 , cell junction , epithelium , biophysics , biology , biochemistry , cell , membrane , apoptosis , genetics , permeability (electromagnetism)
Alcohol consumption promotes loss of intestinal barrier function. However, mechanisms by which ethanol affects the tight junction ( TJ ), the cellular structure responsible for maintaining the gut epithelial barrier, are not well understood. Three classes of transmembrane proteins comprise TJ s: occludin, claudins, and junctional adhesion molecules ( JAM s). It has recently been postulated that JAM ‐A (F11R), the most abundant JAM expressed in intestinal epithelium, regulates “leak” pathway flux, a paracellular route for the nonselective permeation of large solutes. Since transluminal flux of many gut‐derived antigens occurs through this pathway, we investigated the role of JAM ‐A in ethanol‐induced disruption of the intestinal epithelial barrier. Using Caco‐2 and SK ‐ CO 15 monolayers, we found that ethanol induced a dose‐ and time‐dependent decrease in JAM ‐A protein expression to about 70% of baseline levels. Alcohol also reduced Ras‐related protein 2 (Rap2) activity, and enhanced myosin light chain kinase ( MLCK ) activity, changes consistent with impaired JAM ‐A signaling. Stable overexpression and sh RNA ‐mediated knockdown of JAM ‐A were employed to investigate the role of JAM ‐A in paracellular‐mediated flux following alcohol exposure. The paracellular flux of 40‐ kD a fluorescein isothiocynate ( FITC )‐dextran following ethanol treatment was decreased by the overexpression of JAM ‐A; conversely, flux was enhanced by JAM ‐A knockdown. Thus, we conclude that ethanol‐mediated control of JAM ‐A expression and function contributes to mechanisms by which this chemical induces intestinal epithelial leakiness.