title: Functional coupling of tight junctions and microfilaments in T84 monolayers.
abstract: The actin-binding agent cytochalasin D (CD) in intact intestinal epithelium appears to elicit segmentation and contraction of a perijunctional ring of actomyosin and, consequently, to diminish tight junction resistance. We determined if an intestinal epithelial model composed of T84 cells also displayed such a perijunctional cytoskeletal specialization and, if so, whether exposure to CD also affected the tight junction barrier. We find T84 cells display a prominent perijunctional microfilament ring that is actin rich. CD elicits large decreases in transepithelial resistance due specifically to perturbed tight junction permeability as determined with dual Na+-mannitol flux analysis. Transepithelial mannitol and insulin fluxes also increase after CD exposure, but these molecules remain differentially restricted in accordance with their sizes, indicating that gross disruption of the monolayer has not occurred. Structurally, CD elicits segmentation and condensation of the perijunctional ring into actin-rich plaques. These features have similarity to those seen in native intestinal epithelia. This system may represent a simple model for studies of cytoskeletal-tight junction relationships.
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: J L
authors.initials: JL
authors.lastname: Madara
authors.forename: J
authors.initials: J
authors.lastname: Stafford
authors.forename: D
authors.initials: D
authors.lastname: Barenberg
authors.forename: S
authors.initials: S
authors.lastname: Carlson
mesh_terms: D008841:Actin Cytoskeleton / Q000502:physiology*; D002460:Cell Line; D003106:Colon / Q000166:cytology* / Q000378:metabolism / Q000502:physiology; D015638:Cytochalasin D; D003572:Cytochalasins / Q000494:pharmacology; D003584:Cytological Techniques; D003599:Cytoskeleton / Q000502:physiology*; D004553:Electric Conductivity; D006801:Humans; D007365:Intercellular Junctions / Q000378:metabolism / Q000502:physiology*; D010539:Permeability
chemical_list: D003572:Cytochalasins; D015638:Cytochalasin D