Search results for "Cell junction"
showing 10 items of 14 documents
Effect of intermittent shear stress on corneal epithelial cells using an in vitro flow culture model.
2018
Abstract Purpose The aim of this study was to establish and to evaluate an in vitro model for culturing human telomerase-immortalized corneal epithelial (hTCEpi) cells under adjustable medium flow mimicking the movements of the tear film on the ocular surface. Methods Using an IBIDI pump system, cells were cultured under unidirectional, continuous or oscillating, discontinuous medium flow. Cell surface and cytoskeletal architecture were investigated by scanning electron microscopy and immunofluorescence. Gene expression of e-cadherin, occludin, tight junction protein (TJP), desmoplakin, desmocollin and mucins was investigated by real-time PCR. Protein expression of desmoplakin, TJP, occludi…
Nitric Oxide System and Bronchial Epithelium: More Than a Barrier
2021
Airway epithelium forms a physical barrier that protects the lung from the entrance of inhaled allergens, irritants, or microorganisms. This epithelial structure is maintained by tight junctions, adherens junctions and desmosomes that prevent the diffusion of soluble mediators or proteins between apical and basolateral cell surfaces. This apical junctional complex also participates in several signaling pathways involved in gene expression, cell proliferation and cell differentiation. In addition, the airway epithelium can produce chemokines and cytokines that trigger the activation of the immune response. Disruption of this complex by some inflammatory, profibrotic, and carcinogens agents c…
Clostridium difficile Toxins Disrupt Epithelial Barrier Function by Altering Membrane Microdomain Localization of Tight Junction Proteins
2001
ABSTRACT The anaerobic bacterium Clostridium difficile is the etiologic agent of pseudomembranous colitis. C. difficile toxins TcdA and TcdB are UDP-glucosyltransferases that monoglucosylate and thereby inactivate the Rho family of GTPases (W. P. Ciesla, Jr., and D. A. Bobak, J. Biol. Chem. 273:16021–16026, 1998). We utilized purified reference toxins of C. difficile , TcdA-10463 (TcdA) and TcdB-10463 (TcdB), and a model intestinal epithelial cell line to characterize their influence on tight-junction (TJ) organization and hence to analyze the mechanisms by which they contribute to the enhanced paracellular permeability and disease pathophysiology of pseudomembranous colitis. The increase i…
Shortstop Recruits EB1/APC1 and Promotes Microtubule Assembly at the Muscle-Tendon Junction
2003
Abstract Background: Shot (previously named Kakapo), is a Drosophila Plakin family member containing both Actin binding and microtubule binding domains. In Drosophila , it is required for a wide range of processes, including axon extension, dendrite formation, axonal terminal arborization at the neuromuscular junction, tendon cell development, and adhesion of wing epithelium. Results: To address how Shot exerts its activity at the molecular level, we investigated the molecular interactions of Shot with candidate proteins in mature larval tendon cells. We show that Shot colocalizes with EB1/APC1 and with a compact microtubule array extending between the muscle-tendon junction and the cuticle…
Maintenance of the intestinal tube in Caenorhabditis elegans: the role of the intermediate filament protein IFC-2.
2008
The Caenorhabditis elegans intestinal lumen is surrounded by a dense cytoplasmic network that is laterally attached to the junctional complex and is referred to as the endotube. It localizes to the terminal web region which anchors the microvillar actin filament bundles and is particularly rich in intermediate filaments. To examine their role in intestinal morphogenesis and function, C. elegans reporter strains were generated expressing intestine-specific CFP-tagged intermediate filament polypeptide IFB-2. When these animals were treated with dsRNA against intestinal intermediate filament polypeptide IFC-2, the endotube developed multiple bubble-shaped invaginations that protruded into the …
Complexus adhaerentes, a new group of desmoplakin-containing junctions in endothelial cells: II. Different types of lymphatic vessels.
1994
Abstract In diverse mammalian species, including (man, cow and rat) the very flat endothelial cells of lymphatic vessels of various organs, including the retothelial meshwork of sinus of lymph nodes, are connected by zonula -like plaque-bearing junctions which differ from the similarly structured junctions of blood vessel endothelia by the presence of desmoplakin or an as yet unknown but closely related plaque protein. These extended junctions, which also contain plakoglobin but none of the presently known desmogleins and desmocollins, are therefore different from the spot-like desmosomes ( maculae adhaerentes ) present in epithelia, myocardium and dendritic reticulum cells of lymphatic fol…
Utilization of metabolic energy in treatment of ocular surface disorders: polyphosphate as an energy source for corneal epithelial cell proliferation.
2019
Impaired regeneration of the corneal epithelium, as found in many ocular surface diseases, is a major clinical problem in ophthalmology. We hypothesized that corneal epithelial regeneration can be promoted by the physiological, energy-delivering as well as “morphogenetically active” polymer, inorganic polyphosphate (polyP). Corneal limbal explants (diameter, 4 mm) were cultivated on collagen-coated well plates in the absence or presence of polyP (chain length, ∼40 Pi units; 50 μg ml−1) or human platelet lysate (hp-lysate; 5% v/v). Cell outgrowth and differentiation were analyzed after staining with DRAQ5 (nuclei) and rhodamine phalloidin (cytoskeleton), as well as by environmental scanning …
Intestinal absorption enhancement via the paracellular route by fatty acids, chitosans and others: a target for drug delivery.
2005
Peroral delivery of hydrophilic drugs is one of the greatest challenges in biopharmaceutical research. Hydrophilic drugs usually present low bioavailability after oral administration. One of the causes of this low bioavailability is their poor intestinal permeation through the paracellular pathway. This pathway is actually restricted by the presence of tight junctions at the apical side of the enterocytes. In the last few years, great interest has been focused on the structure and cellular regulation of tight junctions, materializing in more in-depth knowledge of this intestinal barrier. Simultaneously, and on the basis of this understanding, continuous efforts are being made to develop age…
Tumor dedifferentiation: an important step in tumor invasion.
1985
Tumor invasion in vivo was studied by light and electron microscopy as well as by immunofluorescence microscopy. Special regard was paid to the grade of tumor differentiation. Dimethylhydrazine-induced murine colonic carcinomas comprising a differentiated and an undifferentiated tumor type with low and high invasiveness respectively, were used. At the invasion front of both tumor types a striking dissociation of the organized tumor cell complexes into isolated tumor cells was found together with a loss of most of the cytological features of differentiation. It is supposed that this process mobilizes the tumor cells from the main tumor bulk enabling them to invade the host tissue by active l…
Gap junctional intercellular communication of cultured rat liver parenchymal cells is stabilized by epithelial cells and their isolated plasma membra…
1994
The gap junctional intercellular communication (GJIC) determined by measuring dye coupling with Lucifer yellow, decreased within 3 d from 66% to 28% in monocultures of rat liver parenchymal cells. Coculturing of the parenchymal cells with a nonparenchymal epithelial cell line from rat liver resulted in increased and stabilized intercellular communication (83% after 3 d). The presence of isolated plasma membrane vesicles of the nonparenchymal epithelial cells also stabilized the intercellular communication between the liver parenchymal cells (70% after 3 d). When liver parenchymal cells were cocultured with a rat liver fibroblast cell line the gap junctional communication between the parench…