title: Mechanism of IFN-gamma-induced endocytosis of tight junction proteins: myosin II-dependent vacuolarization of the apical plasma membrane.
abstract: Disruption of epithelial barrier by proinflammatory cytokines such as IFN-gamma represents a major pathophysiological consequence of intestinal inflammation. We have previously shown that IFN-gamma increases paracellular permeability in model T84 epithelial cells by inducing endocytosis of tight junction (TJ) proteins occludin, JAM-A, and claudin-1. The present study was designed to dissect mechanisms of IFN-gamma-induced endocytosis of epithelial TJ proteins. IFN-gamma treatment of T84 cells resulted in internalization of TJ proteins into large actin-coated vacuoles that originated from the apical plasma membrane and resembled the vacuolar apical compartment (VAC) previously observed in epithelial cells that lose cell polarity. The IFN-gamma dependent formation of VACs required ATPase activity of a myosin II motor but was not dependent on rapid turnover of F-actin. In addition, activated myosin II was observed to colocalize with VACs after IFN-gamma exposure. Pharmacological analyses revealed that formation of VACs and endocytosis of TJ proteins was mediated by Rho-associated kinase (ROCK) but not myosin light chain kinase (MLCK). Furthermore, IFN-gamma treatment resulted in activation of Rho GTPase and induced expressional up-regulation of ROCK. These results, for the first time, suggest that IFN-gamma induces endocytosis of epithelial TJ proteins via RhoA/ROCK-mediated, myosin II-dependent formation of VACs.
authors.affiliation: Epithelial Pathobiology Research Unit, Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA 30322, USA.
authors.forename: Markus
authors.initials: M
authors.lastname: Utech
authors.forename: Andrei I
authors.initials: AI
authors.lastname: Ivanov
authors.forename: Stanislav N
authors.initials: SN
authors.lastname: Samarin
authors.forename: Matthias
authors.initials: M
authors.lastname: Bruewer
authors.forename: Jerrold R
authors.initials: JR
authors.lastname: Turner
authors.forename: Randall J
authors.initials: RJ
authors.lastname: Mrsny
authors.forename: Charles A
authors.initials: CA
authors.lastname: Parkos
authors.forename: Asma
authors.initials: A
authors.lastname: Nusrat
mesh_terms: D000199:Actins / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology* / Q000648:ultrastructure; D016764:Cell Polarity; D062445:Claudin-1; D004705:Endocytosis; D004847:Epithelial Cells / Q000502:physiology / Q000648:ultrastructure; D007371:Interferon-gamma / Q000494:pharmacology / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins / Q000378:metabolism*; D024462:Myosin Type II / Q000502:physiology*; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism; D062793:Occludin; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011994:Recombinant Proteins; D019108:Tight Junctions / Q000502:physiology*; D015854:Up-Regulation; D014617:Vacuoles / Q000502:physiology*; D020741:rho GTP-Binding Proteins / Q000378:metabolism; D054460:rho-Associated Kinases
chemical_list: D000199:Actins; D062445:Claudin-1; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D062793:Occludin; D011994:Recombinant Proteins; D007371:Interferon-gamma; D000255:Adenosine Triphosphate; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D009219:Myosin-Light-Chain Kinase; D024462:Myosin Type II; D020741:rho GTP-Binding Proteins