scholarly journals Reevaluating the Role ofAcanthamoebaProteases in Tissue Invasion: Observation of Cytopathogenic Mechanisms on MDCK Cell Monolayers and Hamster Corneal Cells

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Maritza Omaña-Molina ◽  
Arturo González-Robles ◽  
Lizbeth Iliana Salazar-Villatoro ◽  
Jacob Lorenzo-Morales ◽  
Ana Ruth Cristóbal-Ramos ◽  
...  
Keyword(s):  
Conditioned Medium ◽  
Corneal Epithelium ◽  
Mdck Cell ◽  
Mechanical Effect ◽  
Cell Junctions ◽  
Corneal Tissue ◽  
Tissue Destruction ◽  
Cell Monolayers ◽  
Quantitative Analyses ◽  
Cellular Separation

The morphological analysis of the cytopathic effect on MDCK cell monolayers and hamster cornea and qualitative and quantitative analyses of conditioned medium and proteases were evaluated and compared between two strains ofAcanthamoebagenotype T4. Further than highlighting the biological differences found between both strains, the most important observation in this study was the fact that proteases both in total extracts and in conditioned medium are apparently not determinant in tissue destruction. An interestingly finding was that no lysis of corneal tissue was observed as it was previously suggested. These results, together with previous studies, allow us to conclude that the invasion and disruption of corneal tissue is performed by the penetration of the amoebae through cell junctions, either by the action of proteases promoting cellular separation but not by their destruction and/or a mechanical effect exerted by amoebae. Therefore, contact-dependent mechanisms inAcanthamoebapathogenesis are more relevant than it has been previously considered. This is supported because the phagocytosis of recently detached cells as well as those attached to the corneal epithelium leads to the modification of the cellular architecture facilitating the migration and destruction of deeper layers of the corneal epithelium.

Novel bUT-B2 urea transporter isoform is constitutively activated

2009 ◽  
Vol 297 (2) ◽  
pp. R323-R329 ◽  
Author(s):  
P. Tickle ◽  
A. Thistlethwaite ◽  
C. P. Smith ◽  
G. S. Stewart
Keyword(s):  
Protein Kinase ◽  
Transient Response ◽  
Mdck Cell ◽  
Kinase Activity ◽  
Intracellular Camp ◽  
Protein Kinase Activity ◽  
Urea Transport ◽  
Urea Transporter ◽  
Cell Monolayers ◽  
Human Orthologs

Our previous studies have detailed a novel facilitative UT-B urea transporter isoform, bUT-B2. Despite the existence of mouse and human orthologs, the functional characteristics of UT-B2 remain undefined. In this report, we produced a stable MDCK cell line that expressed bUT-B2 protein and investigated the transepithelial urea flux across cultured cell monolayers. We observed a large basal urea flux that was significantly reduced by known inhibitors of facilitative urea transporters; 1,3 dimethylurea ( P < 0.001, n = 17), thionicotinamide ( P < 0.05, n = 11), and phloretin ( P < 0.05, n = 9). Pre-exposure for 1 h to the antidiuretic hormone vasopressin had no effect on bUT-B2-mediated urea transport (NS, n = 3). Acute vasopressin exposure for up to 30 min also failed to elicit any transient response (NS, n = 9). Further investigation confirmed that bUT-B2 function was not affected by alteration of intracellular cAMP (NS, n = 4), intracellular calcium (NS, n = 3), or protein kinase activity (NS, n = 4). Finally, immunoblot data suggested a possible role for glycosylation in regulating bUT-B2 function. In conclusion, this study showed that bUT-B2-mediated transepithelial urea transport was constitutively activated and unaffected by known regulators of renal UT-A urea transporters.

Transport of iron chelators and chelates across MDCK cell monolayers: implications for iron excretion during chelation therapy

2010 ◽  
Vol 91 (3) ◽  
pp. 401-412 ◽  
Author(s):  
Xi-Ping Huang ◽  
Jake J. Thiessen ◽  
Michael Spino ◽  
Douglas M. Templeton
Keyword(s):  
Mdck Cell ◽  
Chelation Therapy ◽  
Iron Chelators ◽  
Cell Monolayers ◽  
Iron Excretion

Effect of stretch on structural integrity and micromechanics of human alveolar epithelial cell monolayers exposed to thrombin

2006 ◽  
Vol 290 (6) ◽  
pp. L1104-L1110 ◽  
Author(s):  
Xavier Trepat ◽  
Ferranda Puig ◽  
Nuria Gavara ◽  
Jeffrey J. Fredberg ◽  
Ramon Farre ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Epithelial Cell ◽  
Structural Integrity ◽  
Alveolar Epithelial Cell ◽  
Compressive Strain ◽  
Cell Junctions ◽  
Cell Monolayers ◽  
Alveolar Epithelial ◽  
Epithelial Cell Monolayers ◽  
Human Alveolar Epithelial Cell

Alveolar epithelial cells in patients with acute lung injury subjected to mechanical ventilation are exposed to increased procoagulant activity and mechanical strain. Thrombin induces epithelial cell stiffening, contraction, and cytoskeletal remodeling, potentially compromising the balance of forces at the alveolar epithelium during cell stretching. This balance can be further compromised by the loss of integrity of cell-cell junctions in the injured epithelium. The aim of this work was to study the effect of stretch on the structural integrity and micromechanics of human alveolar epithelial cell monolayers exposed to thrombin. Confluent and subconfluent cells (A549) were cultured on collagen-coated elastic substrates. After exposure to thrombin (0.5 U/ml), a stepwise cell stretch (20%) was applied with a vacuum-driven system mounted on an inverted microscope. The structural integrity of the cell monolayers was assessed by comparing intercellular and intracellular strains within the monolayer. Strain was measured by tracking beads tightly bound to the cell surface. Simultaneously, cell viscoelasticity was measured using optical magnetic twisting cytometry. In confluent cells, thrombin did not induce significant changes in transmission of strain from the substrate to overlying cells. By contrast, thrombin dramatically impaired the ability of subconfluent cells to follow imposed substrate deformation. Upon substrate unstretching, thrombin-treated subconfluent cells exhibited compressive strain (9%). Stretch increased stiffness (56–62%) and decreased cell hysteresivity (13–22%) of vehicle cells. By contrast, stretch did not increase stiffness of thrombin-treated cells, suggesting disruption of cytoskeletal structures. Our findings suggest that thrombin could exacerbate epithelial barrier dysfunction in injured lungs subjected to mechanical ventilation.

scholarly journals Influenza neuraminidase is delivered directly to the apical surface of MDCK cell monolayers

FEBS Letters ◽  
1989 ◽  
Vol 244 (1) ◽  
pp. 57-60 ◽  
Author(s):  
Phillipa U. Daniels ◽  
J.Michael Edwardson
Keyword(s):  
Mdck Cell ◽  
Apical Surface ◽  
Cell Monolayers

Stem Cell-Like Characteristics of Corneal Epithelial Cells

2014 ◽  
Vol 998-999 ◽  
pp. 312-315
Author(s):  
Fan Wang ◽  
Bo Ren ◽  
Yi Ning Yan
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Epithelial Cells ◽  
Corneal Epithelium ◽  
Cell Activity ◽  
Stem Cell Marker ◽  
Corneal Tissue ◽  
Limbal Stem Cells ◽  
Corneal Epithelial Cells ◽  
Corneal Epithelial

Purpose: The adult corneal epithelium is maintained by a population of limbal stem cells (LSCs), transmembrane protein prominin, regarded as stem cell marker was investigated on mouse corneal tissue, to study weather contains CD133-expressing cells and their distribution. Methods: Enucleated mouse eyes were embedded in OCT and cryosections were performed for mmunohistochemical studies using the avidin-biotin-peroxidase complex (ABC) procedure. Meanwhile, dissected mouse corneas were analyzed by westernblot. Results: In the adult mouse, 13A4 immunoreactivity was detected at the apical side of superficial corneal epithelium, including the limbus region, but not by stroma and endothelium. 115 KDa protein was approved in corneal tissue by Westernblot. Conclusions: The stem cell activity does not occur along the limbus but presumably presented by small portion of corneal epithelial cells which may hold a similar properties of stem cells.

scholarly journals Human Cytomegalovirus US7, US8, US9, and US10 Are Cytoplasmic Glycoproteins, Not Found at Cell Surfaces, and US9 Does Not Mediate Cell-to-Cell Spread

2002 ◽  
Vol 76 (11) ◽  
pp. 5748-5758 ◽  
Author(s):  
Mary T. Huber ◽  
Roman Tomazin ◽  
Todd Wisner ◽  
Jessica Boname ◽  
David C. Johnson
Keyword(s):  
Membrane Proteins ◽  
Epithelial Cells ◽  
Human Cytomegalovirus ◽  
Cell Junctions ◽  
Direct Role ◽  
Cell Monolayers ◽  
Mediate Cell ◽  
Class Ii Antigen ◽  
Golgi Network ◽  
Cell Spread

ABSTRACT Human cytomegalovirus (HCMV) expresses a large number of membrane proteins with unknown functions. One class of these membrane proteins apparently acts to allow HCMV to escape detection by the immune system. The best characterized of these are the glycoproteins encoded within the US2 to US11 region of the HCMV genome that mediate resistance to CD8+ and CD4+ T cells. US2, US3, US6, and US11 block various aspects of the major histocompatibility complex (MHC) class I and class II antigen presentation pathways, functioning in cytoplasmic membranes to cause retention, degradation, or mislocalization of MHC proteins. Distantly homologous genes in this region, US7, US8, US9, and US10, are not well characterized. Here, we report expression of the glycoproteins encoded by US7 to US10 by using replication-defective adenovirus (Ad) vectors. US7, US9, and US10 remained sensitive to endoglycosidase H and were exclusively or largely present in the endoplasmic reticulum (ER) as determined by confocal microscopy. US8 reached the Golgi apparatus and trans-Golgi network and was more quickly degraded. Previous studies suggested that US9 could localize to cell junctions and mediate cell-to-cell spread in ARPE-19 retinal epithelial cells. We found no evidence of US9 at cell junctions of HEC-1A epithelial cells. HCMV recombinants lacking US9 produced smaller plaques on ARPE-19 cell monolayers but also exhibited defects in virus replication compared with wild-type HCMV in these cells. Other HCMV recombinants constructed in a similar fashion that were able to express US9 also produced small plaques and some of these exhibited defects in production of infectious progeny in ARPE-19 cells. Thus, there was no correlation between defects in cell-to-cell spread (plaque size) and loss of expression of US9, and it is possible that US9− mutants produce smaller plaques because they produce fewer progeny. Together, our results do not support the hypothesis that US9 plays a direct role in HCMV cell-to-cell spread.

SECRETORY IgA BLOCKS HYPOXIA AUGMENTED BACTERIAL PASSAGE ACROSS MDCK CELL MONOLAYERS

Shock ◽  
1997 ◽  
Vol 7 (Supplement) ◽  
pp. 32
Author(s):  
L N Diebel ◽  
D M Liberati ◽  
W J Brown
Keyword(s):  
Mdck Cell ◽  
Secretory Iga ◽  
Cell Monolayers
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