Activation of focal adhesion kinase via M1 muscarinic acetylcholine receptor is required in restitution of intestinal barrier function after epithelial injury

• Published in: Biochimica et biophysica acta Vol. 1842; no. 4; pp. 635 - 645
• Main Authors: Khan, Md Rafiqul Islam, Yazawa, Takashi, Anisuzzaman, Abu Syed Md, Semba, Shingo, Ma, Yanju, Uwada, Junsuke, Hayashi, Hisayoshi, Suzuki, Yuichi, Ikeuchi, Hiroki, Uchino, Motoi, Maemoto, Atsuo, Muramatsu, Ikunobu, Taniguchi, Takanobu
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.04.2014
• Subjects: Cell Line, Tumor; Electric Impedance; Enzyme Activation; Epithelial barrier function; Extracellular Signal-Regulated MAP Kinases - analysis; Extracellular Signal-Regulated MAP Kinases - physiology; Focal adhesion kinase; Focal Adhesion Protein-Tyrosine Kinases - analysis; Focal Adhesion Protein-Tyrosine Kinases - physiology; Humans; IBD; Immunohistochemistry; Interferon-gamma - pharmacology; Intestinal Mucosa - metabolism; mAChR; Phosphorylation; Receptor, Muscarinic M1 - analysis; Receptor, Muscarinic M1 - physiology; IBD; Focal adhesion kinase; mAChR; Epithelial barrier function
• ISSN: 0925-4439; 0006-3002; 1879-260X; 1878-2434
• DOI: 10.1016/j.bbadis.2013.12.007

Impairment of epithelial barrier is observed in various intestinal disorders including inflammatory bowel diseases (IBD). Numerous factors may cause temporary damage of the intestinal epithelium. A complex network of highly divergent factors regulates healing of the epithelium to prevent inflammatory response. However, the exact repair mechanisms involved in maintaining homeostatic intestinal barrier integrity remain to be clarified. In this study, we demonstrate that activation of M1 muscarinic acetylcholine receptor (mAChR) augments the restitution of epithelial barrier function in T84 cell monolayers after ethanol-induced epithelial injury, via ERK-dependent phosphorylation of focal adhesion kinase (FAK). We have shown that ethanol injury decreased the transepithelial electrical resistance (TER) along with the reduction of ERK and FAK phosphorylation. Carbachol (CCh) increased ERK and FAK phosphorylation with enhanced TER recovery, which was completely blocked by either MT-7 (M1 antagonist) or atropine. The CCh-induced enhancement of TER recovery was also blocked by either U0126 (ERK pathway inhibitor) or PF-228 (FAK inhibitor). Treatment of T84 cell monolayers with interferon-γ (IFN-γ) impaired the barrier function with the reduction of FAK phosphorylation. The CCh-induced ERK and FAK phosphorylation were also attenuated by the IFN-γ treatment. Immunological and binding experiments exhibited a significant reduction of M1 mAChR after IFN-γ treatment. The reduction of M1 mAChR in inflammatory area was also observed in surgical specimens from IBD patients, using immunohistochemical analysis. These findings provide important clues regarding mechanisms by which M1 mAChR participates in the maintenance of intestinal barrier function under not only physiological but also pathological conditions. •A role of muscarinic acetylcholine receptor (mAChR) in epithelial barrier function is explored.•M1 subtype of mAChR enhances intestinal barrier recovery after injury.•The order of signaling cascade is M1, MAP kinase and focal adhesion kinase (FAK) to regulate barrier function.•Interferon-γ results in the reduction of epithelial barrier, M1 density and FAK activity.