Open AccessInterferon‐gamma signals via an ERK1/2‐ARF6 pathway to promote bacterial internalization by gut epithelia
Author(s) -
Smyth David,
McKay Catherine M.,
Gulbransen Brian D.,
Phan Van C.,
Wang Arthur,
McKay Derek M.
Publication year - 2012
Publication title -
cellular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.542
H-Index - 138
eISSN - 1462-5822
pISSN - 1462-5814
DOI - 10.1111/j.1462-5822.2012.01796.x
Subject(s) - transcytosis , internalization , transcellular , paracellular transport , biology , endocytosis , microbiology and biotechnology , barrier function , epithelium , tight junction , interferon , intestinal epithelium , intestinal mucosa , mapk/erk pathway , kinase , cell , immunology , biochemistry , permeability (electromagnetism) , medicine , genetics , membrane
Summary The barrier function of the epithelium lining the intestine is essential for health by preventing the free passage of colonic bacteria into the mucosa. Epithelia treated with interferon (IFN)‐γ display increased bacteria transcytosis. Much is known of how IFNγ affects the tight junction and paracellular permeability, yet its role in modifying transcellular traffic of commensal bacteria remains poorly understood. Using immunoblotting, ELISA and immunolocalization, IFNγ was found to activate extracellular regulated kinase (ERK)1/2 in the human colon‐like T84 epithelial cell line. Pharmacological inhibition of MEK/ERK1/2 signalling with U0126 significantly inhibited IFNγ‐induced increases in the transcytosis of non‐invasive Escherichia coli (strain HB101). IFNγ treatment enhanced epithelial internalization of E. coli , some of which subsequently escaped the enterocyte. Molecular analyses revealed that ERK1/2 inhibition prevented activation of the ADP‐ribosylation factor (ARF)‐6, a protein associated with endocytosis, and that siRNA knock‐down of ARF6 expression reduced IFNγ‐induced E. coli internalization into T84 cells. None of these interventions affected the drop in transepithelial resistance caused by IFNγ. Thus, increased transcellular passage may be a major component of IFNγ‐induced increases in epithelial permeability, and ERK1/2 and ARF6 are presented as important molecules in IFNγ‐evoked transcytosis of bacteria across gut epithelia.