title: Cyclic stretch induces alveolar epithelial barrier dysfunction via calpain-mediated degradation of p120-catenin.
abstract: Lung hyperinflation is known to be an important contributing factor in the pathogenesis of ventilator-induced lung injury. Mechanical stretch causes epithelial barrier dysfunction and an increase in alveolar permeability, although the precise mechanisms have not been completely elucidated. p120-catenin is an adherens junction-associated protein that regulates cell-cell adhesion. In this study, we determined the role of p120-catenin in cyclic stretch-induced alveolar epithelial barrier dysfunction. Cultured alveolar epithelial cells (MLE-12) were subjected to uniform cyclic (0.5 Hz) biaxial stretch from 0 to 8 or 20% change in surface area for 0, 1, 2, or 4 h. At the end of the experiments, cells were lysed to determine p120-catenin expression by Western blot analysis. Immunofluorescence staining of p120-catenin and F-actin was performed to assess the integrity of monolayers and interepithelial gap formation. Compared with unstretched control cells, 20% stretch caused a significant loss in p120-catenin expression, which was coupled to interepithelial gap formation. p120-Catenin knockdown with small interfering RNA (siRNA) dose dependently increased stretch-induced gap formation, whereas overexpression of p120-catenin abolished stretch-induced gap formation. Furthermore, pharmacological calpain inhibition or depletion of calpain-1 with a specific siRNA prevented p120-catenin loss and subsequent stretch-induced gap formation. Our findings demonstrate that p120-catenin plays a critical protective role in cyclic stretch-induced alveolar barrier dysfunction, and, thus, maintenance of p120-catenin expression may be a novel therapeutic strategy for the prevention and treatment of ventilator-induced lung injury.
authors.affiliation: Department of Pharmacology, University of Illinois College of Medicine, Chicago, IL 60612, USA.
authors.forename: Yuelan
authors.initials: Y
authors.lastname: Wang
authors.forename: Richard D
authors.initials: RD
authors.lastname: Minshall
authors.forename: David E
authors.initials: DE
authors.lastname: Schwartz
authors.forename: Guochang
authors.initials: G
authors.lastname: Hu
mesh_terms: D000818:Animals; D015824:Blood-Air Barrier / Q000503:physiopathology*; D015153:Blotting, Western; D002154:Calpain / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051177:Catenins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells; D004848:Epithelium / Q000473:pathology / Q000503:physiopathology; D005455:Fluorescent Antibody Technique; D042541:Intracellular Space; D051379:Mice; D011650:Pulmonary Alveoli / Q000473:pathology / Q000503:physiopathology*; D034741:RNA, Small Interfering / Q000008:administration & dosage; D013194:Staining and Labeling; D013312:Stress, Physiological; D014162:Transfection; D015854:Up-Regulation; D000095002:Delta Catenin
chemical_list: D051177:Catenins; D034741:RNA, Small Interfering; D002154:Calpain; D000095002:Delta Catenin; C000722349:Ctnnd1 protein, mouse