scholarly journals Inhibition of N-glycosylation by tunicamycin attenuates cell–cell adhesion via impaired desmosome formation in normal human epidermal keratinocytes

2018 ◽  
Vol 38 (6) ◽  
Author(s):  
Seon-Pil Jin ◽  
Jin Ho Chung
Keyword(s):  
Cell Adhesion ◽  
Adhesive Strength ◽  
Epidermal Keratinocytes ◽  
Primary Keratinocytes ◽  
Human Epidermal Keratinocytes ◽  
Tissue Integrity ◽  
Cell Adhesive ◽  
Protein Functions ◽  
The Stability ◽  
Cell Cell

N-Glycosylation affects protein functions such as location, stability, and susceptibility to proteases. Desmosomes in keratinocytes are essential to maintain epidermal tissue integrity to protect against environmental insults. However, it is not yet known whether N-glycosylation affects desmosomal functions in primary keratinocytes. Tunicamycin is an inhibitor of N-glycosylation that has been a useful tool in glycobiology. Therefore, we investigated the effect of inhibiting N-glycosylation by tunicamycin treatment on desmosomes in primary keratinocytes. In our experiments, cell–cell adhesive strength was reduced in tunicamycin-treated primary keratinocytes. TEM showed that desmosome formation was impaired by tunicamycin. Desmogleins (Dsgs) 1 and 3, which constitute the core structure of desmosomes, were well transported to the cell–cell borders, but the amount decreased and showed an aberrant distribution at the cell borders in tunicamycin-treated keratinocytes. The stability of both desmoglein proteins was also reduced, and they were degraded through both proteasomal and lysosomal pathways, although inhibiting degradation did not restore the cell–cell adhesion. Finally, tunicamycin induced desmosomal instability, enhancing their disassembly. In conclusion, these results indicate that N-glycosylation is critical to the desmosome complex to maintain cell–cell adhesive strength in primary keratinocytes.

scholarly journals RAC1 Regulates Adherens Junctions through Endocytosis of E-Cadherin

2001 ◽  
Vol 12 (4) ◽  
pp. 847-862 ◽  
Author(s):  
Nasreen Akhtar ◽  
Neil A. Hotchin
Keyword(s):  
Cell Adhesion ◽  
Fluorescent Protein ◽  
Adherens Junctions ◽  
Expression Vectors ◽  
Epidermal Keratinocytes ◽  
Human Epidermal Keratinocytes ◽  
Cell Contacts ◽  
Green Fluorescent ◽  
E Cadherin ◽  
Cell Cell

The establishment of cadherin-dependent cell–cell contacts in human epidermal keratinocytes are known to be regulated by the Rac1 small GTP-binding protein, although the mechanisms by which Rac1 participates in the assembly or disruption of cell–cell adhesion are not well understood. In this study we utilized green fluorescent protein (GFP)-tagged Rac1 expression vectors to examine the subcellular distribution of Rac1 and its effects on E-cadherin–mediated cell–cell adhesion. Microinjection of keratinocytes with constitutively active Rac1 resulted in cell spreading and disruption of cell–cell contacts. The ability of Rac1 to disrupt cell–cell adhesion was dependent on colony size, with large established colonies being resistant to the effects of active Rac1. Disruption of cell–cell contacts in small preconfluent colonies was achieved through the selective recruitment of E-cadherin–catenin complexes to the perimeter of multiple large intracellular vesicles, which were bounded by GFP-tagged L61Rac1. Similar vesicles were observed in noninjected keratinocytes when cell–cell adhesion was disrupted by removal of extracellular calcium or with the use of an E-cadherin blocking antibody. Moreover, formation of these structures in noninjected keratinocytes was dependent on endogenous Rac1 activity. Expression of GFP-tagged effector mutants of Rac1 in keratinocytes demonstrated that reorganization of the actin cytoskeleton was important for vesicle formation. Characterization of these Rac1-induced vesicles revealed that they were endosomal in nature and tightly colocalized with the transferrin receptor, a marker for recycling endosomes. Expression of GFP-L61Rac1 inhibited uptake of transferrin-biotin, suggesting that the endocytosis of E-cadherin was a clathrin-independent mechanism. This was supported by the observation that caveolin, but not clathrin, localized around these structures. Furthermore, an inhibitory form of dynamin, known to inhibit internalization of caveolae, inhibited formation of cadherin vesicles. Our data suggest that Rac1 regulates adherens junctions via clathrin independent endocytosis of E-cadherin.

Expression of a dominant negative cadherin mutant inhibits proliferation and stimulates terminal differentiation of human epidermal keratinocytes

1996 ◽  
Vol 109 (13) ◽  
pp. 3013-3023 ◽  
Author(s):  
A.J. Zhu ◽  
F.M. Watt
Keyword(s):  
Cell Adhesion ◽  
Terminal Differentiation ◽  
Intercellular Adhesion ◽  
Dominant Negative ◽  
Epidermal Keratinocytes ◽  
Dominant Negative Mutant ◽  
Beta Catenin ◽  
Human Epidermal Keratinocytes ◽  
Negative Mutant ◽  
E Cadherin

Cell adhesion molecules are not only required for maintenance of tissue integrity, but also regulate many aspects of cell behaviour, including growth and differentiation. While the regulatory functions of integrin extracellular matrix receptors in keratinocytes are well established, such functions have not been investigated for the primary receptors that mediate keratinocyte intercellular adhesion, the cadherins. To examine cadherin function in normal human epidermal keratinocytes we used a retroviral vector to introduce a dominant negative E-cadherin mutant, consisting of the extracellular domain of H-2Kd and the transmembrane and cytoplasmic domains of E-cadherin. As a control a vector containing the same construct, but with the catenin binding site destroyed, was prepared. High levels of expression of the constructs were achieved; the dominant negative mutant, but not the control, formed complexes with alpha-, beta- and gamma-catenin. In cells expressing the dominant negative mutant there was a 5-fold decrease in the level of endogenous cadherins and a 3-fold increase in the level of beta-catenin. Cell-cell adhesion and stratification were inhibited by the dominant negative mutant and desmosome formation was reduced. Expression of the mutant resulted in reduced levels of the alpha 2 beta 1 and alpha 3 beta 1 integrins and increased cell motility, providing further evidence for cross-talk between cadherins and the beta 1 integrins. In view of the widely documented loss of E-cadherin in keratinocyte tumours it was surprising that the dominant negative mutant had an inhibitory effect on keratinocyte proliferation and stimulated terminal differentiation even under conditions in which intercellular adhesion was prevented. These results establish a role for cadherins in regulating keratinocyte growth and differentiation and raise interesting questions as to the relative importance of cell adhesion-dependent and -independent mechanisms.

Effect of silver nanoparticles on human primary keratinocytes

2013 ◽  
Vol 394 (1) ◽  
pp. 113-123 ◽  
Author(s):  
Radoslaw Szmyd ◽  
Anna Grazyna Goralczyk ◽  
Lukasz Skalniak ◽  
Agnieszka Cierniak ◽  
Barbara Lipert ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Chemical Properties ◽  
Wound Dressings ◽  
Epidermal Keratinocytes ◽  
Primary Keratinocytes ◽  
Human Epidermal Keratinocytes ◽  
Normal Human ◽  
Physical And Chemical ◽  
First Time ◽  
Human Primary Keratinocytes

Abstract Silver nanoparticles (AgNPs) have many biological applications in biomedicine, biotechnology and other life sciences. Depending on the size, shape and the type of carrier, AgNPs demonstrate different physical and chemical properties. AgNPs have strong antimicrobial, antiviral and antifungal activity, thus they are used extensively in a range of medical settings, particularly in wound dressings but also in cosmetics. This study was undertaken to examine the potential toxic effects of 15 nm polyvinylpyrrolidone-coated AgNPs on primary normal human epidermal keratinocytes (NHEK). Cells were treated with different concentrations of AgNPs and then cell viability, metabolic activity and other biological and biochemical aspects of keratinocytes functioning were studied. We observed that AgNPs decrease keratinocyte viability, metabolism and also proliferatory and migratory potential of these cells. Moreover, longer exposure resulted in activation of caspase 3/7 and DNA damage. Our studies show for the first time, that AgNPs may present possible danger for primary keratinocytes, concerning activation of genotoxic and cytotoxic processes depending on the concentration.

scholarly journals Microtubule Disruption in Keratinocytes Induces Cell-Cell Adhesion through Activation of Endogenous E-Cadherin

2001 ◽  
Vol 12 (7) ◽  
pp. 1983-1993 ◽  
Author(s):  
Sun-Ho Kee ◽  
Peter M. Steinert
Keyword(s):  
Cell Adhesion ◽  
Cell Lines ◽  
Epidermal Keratinocytes ◽  
Cell Periphery ◽  
Microtubule Disruption ◽  
Low Calcium ◽  
High Calcium ◽  
Long Term Treatment ◽  
E Cadherin ◽  
Cell Cell

The association of the cytoskeleton with the cadherin–catenin complex is essential for strong cell-cell adhesion in epithelial cells. In this study, we have investigated the effect of microtubule organization on cell-cell adhesion in differentiating keratinocytes. When microtubules of normal human epidermal keratinocytes (NHEKs) grown in low calcium media (0.05 mM) were disrupted with nocodazole or colcemid, cell-cell adhesion was induced through relocalization of the E-cadherin–catenin–actin complex to the cell periphery. This was accompanied by actin polymerization. Also, it was found that microtubule disruption-induced cell-cell adhesion was significantly reduced in more advanced differentiated keratinocytes. For example, when NHEK cells cultured under high calcium (1.2 mM) for 8 d and then in low calcium for 1 d were treated with nocodazole, there was no induction of cell-cell adhesion. Also long-term treatment of a phorbol ester for 48 h inhibited nocodazole-induced cell-cell adhesion of NHEK. Furthermore, this nocodazole-induced cell-cell adhesion could be observed in squamous cancer cell lines (A431 and SCC-5, -9, and -25) under low calcium condition, but not in the keratinocyte cell lines derived from normal epidermis (HaCaT, RHEK). On the other hand, HaCaT cells continuously cultivated in low calcium media regained a less differentiated phenotype such as decreased expression of cytokeratin 10, and increased K5; these changes were accompanied with inducibility of cell-cell adhesion by nocodazole. Together, our results suggest that microtubule disruption can induce the cell-cell adhesion via activation of endogenous E-cadherin in non- or early differentiating keratinocytes. However, this is no longer possible in advanced terminally differentiating keratinocytes, possibly due to irreversible changes effected by cell envelope barrier formation.

scholarly journals Early Events in Actin Cytoskeleton Dynamics and E-Cadherin-Mediated Cell-Cell Adhesion during Epithelial-Mesenchymal Transition

Cells ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 578 ◽  
Author(s):  
Irina Y. Zhitnyak ◽  
Svetlana N. Rubtsova ◽  
Nikita I. Litovka ◽  
Natalya A. Gloushankova
Keyword(s):  
Cell Adhesion ◽  
Epithelial Mesenchymal Transition ◽  
Immunofluorescent Staining ◽  
Actin Binding ◽  
Mesenchymal Transition ◽  
Actin Bundle ◽  
Cell Contacts ◽  
The Stability ◽  
E Cadherin ◽  
Cell Cell

Epithelial-mesenchymal transition (EMT) plays an important role in development and also in initiation of metastasis during cancer. Disruption of cell-cell contacts during EMT allowing cells to detach from and migrate away from their neighbors remains poorly understood. Using immunofluorescent staining and live-cell imaging, we analyzed early events during EMT induced by epidermal growth factor (EGF) in IAR-20 normal epithelial cells. Control cells demonstrated stable adherens junctions (AJs) and robust contact paralysis, whereas addition of EGF caused rapid dynamic changes at the cell-cell boundaries: fragmentation of the circumferential actin bundle, assembly of actin network in lamellipodia, and retrograde flow. Simultaneously, an actin-binding protein EPLIN was phosphorylated, which may have decreased the stability of the circumferential actin bundle. Addition of EGF caused gradual replacement of linear E-cadherin–based AJs with dynamic and unstable punctate AJs, which, unlike linear AJs, colocalized with the mechanosensitive protein zyxin, confirming generation of centripetal force at the sites of cell-cell contacts during EMT. Our data show that early EMT promotes heightened dynamics at the cell-cell boundaries—replacement of stable AJs and actin structures with dynamic ones—which results in overall weakening of cell-cell adhesion, thus priming the cells for front-rear polarization and eventual migration.

scholarly journals DDR1 triggers epithelial cell differentiation by promoting cell adhesion through stabilization of E-cadherin

2011 ◽  
Vol 22 (7) ◽  
pp. 940-953 ◽  
Author(s):  
Yi-Chun Yeh ◽  
Chia-Ching Wu ◽  
Yang-Kao Wang ◽  
Ming-Jer Tang
Keyword(s):  
Cell Adhesion ◽  
Underlying Mechanism ◽  
Dominant Negative ◽  
Cell Junctions ◽  
Dominant Negative Mutant ◽  
Protein Levels ◽  
Epithelial Plasticity ◽  
The Stability ◽  
E Cadherin ◽  
Cell Cell

Discoidin domain receptor 1 (DDR1) promotes E-cadherin–mediated adhesion. The underlying mechanism and its significance, however, have not been elucidated. Here we show that DDR1 overexpression augmented, whereas dominant negative mutant (DN-DDR1) or knockdown of DDR1 inhibited E-cadherin localized in cell-cell junctions in epithelial cells. DDR1 changed the localization and abundance of E-cadherin, as well as epithelial plasticity, as manifested by enhancement of microvilli formation and alteration of cytoskeletal organization. DDR1 also reduced protein abundance of mesenchymal markers, whereas DN-DDR1 and sh-DDR1 showed opposite effects. These results suggest that expression of DDR1 increases epithelial plasticity. Expression of DDR1 augmented E-cadherin protein levels by decreasing its degradation rate. Photobleaching and photoconversion of E-cadherin conjugated with Eos fluorescence protein demonstrated that DDR1 increased the stability of E-cadherin on the cell membrane, whereas sh-DDR1 decreased it. Pull-down assay and expression of constitutively active or dominant-negative Cdc42 showed that DDR1 stabilized E-cadherin through inactivation of Cdc42. Altogether, our results show that DDR1 promotes cell-cell adhesion and differentiation through stabilization of E-cadherin, which is mediated by Cdc42 inactivation.

scholarly journals Dynamic and Static Interactions between p120 Catenin and E-Cadherin Regulate the Stability of Cell-Cell Adhesion

Cell ◽  
2010 ◽  
Vol 141 (1) ◽  
pp. 117-128 ◽  
Author(s):  
Noboru Ishiyama ◽  
Seung-Hye Lee ◽  
Shuang Liu ◽  
Guang-Yao Li ◽  
Matthew J. Smith ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
P120 Catenin ◽  
The Stability ◽  
E Cadherin ◽  
Cell Cell

scholarly journals A genome-wide screen identifies conserved protein hubs required for cadherin-mediated cell–cell adhesion

2014 ◽  
Vol 204 (2) ◽  
pp. 265-279 ◽  
Author(s):  
Christopher P. Toret ◽  
Michael V. D’Ambrosio ◽  
Ronald D. Vale ◽  
Michael A. Simon ◽  
W. James Nelson
Keyword(s):  
Cell Adhesion ◽  
Protein Interactions ◽  
Intracellular Signaling ◽  
Cell Types ◽  
Cytoskeleton Organization ◽  
Drosophila Melanogaster S2 Cells ◽  
Genome Wide ◽  
A Genome ◽  
Protein Functions ◽  
Cell Cell

Cadherins and associated catenins provide an important structural interface between neighboring cells, the actin cytoskeleton, and intracellular signaling pathways in a variety of cell types throughout the Metazoa. However, the full inventory of the proteins and pathways required for cadherin-mediated adhesion has not been established. To this end, we completed a genome-wide (∼14,000 genes) ribonucleic acid interference (RNAi) screen that targeted Ca2+-dependent adhesion in DE-cadherin–expressing Drosophila melanogaster S2 cells in suspension culture. This novel screen eliminated Ca2+-independent cell–cell adhesion, integrin-based adhesion, cell spreading, and cell migration. We identified 17 interconnected regulatory hubs, based on protein functions and protein–protein interactions that regulate the levels of the core cadherin–catenin complex and coordinate cadherin-mediated cell–cell adhesion. Representative proteins from these hubs were analyzed further in Drosophila oogenesis, using targeted germline RNAi, and adhesion was analyzed in Madin–Darby canine kidney mammalian epithelial cell–cell adhesion. These experiments reveal roles for a diversity of cellular pathways that are required for cadherin function in Metazoa, including cytoskeleton organization, cell–substrate interactions, and nuclear and cytoplasmic signaling.

A role for the Drosophila segment polarity gene armadillo in cell adhesion and cytoskeletal integrity during oogenesis

Development ◽  
1993 ◽  
Vol 118 (4) ◽  
pp. 1191-1207 ◽  
Author(s):  
M. Peifer ◽  
S. Orsulic ◽  
D. Sweeton ◽  
E. Wieschaus
Keyword(s):  
Cell Adhesion ◽  
Germ Line ◽  
Adherens Junctions ◽  
Beta Catenin ◽  
Cell Adhesive ◽  
Segment Polarity ◽  
Drosophila Ovary ◽  
Segment Polarity Gene ◽  
Polarity Gene ◽  
Cell Cell

The epithelial sheet is a structural unit common to many tissues. Its organization appears to depend on the function of the multi-protein complexes that form adherens junctions. Elegant cell biological experiments have provided support for hypotheses explaining the function of adherens junctions and of their components. These systems, however, lack the ability to test function within an entire organism during development. The realization that the product of the Drosophila segment polarity gene armadillo is related to the vertebrate adhesive junction components plakoglobin and beta-catenin led to the suggestion that armadillo might provide a genetic handle to study adhesive junction structure and function. An examination of the potential function of Armadillo in cell-cell adhesive junctions was initiated using the Drosophila ovary as the model system. We examined the distribution of Armadillo in the Drosophila ovary and demonstrated that this localization often parallels the location of cell-cell adhesive junctions. The consequences of removing armadillo function from the germ-line cells of the ovary were also examined. Germ-line armadillo mutations appear to disrupt processes requiring cell adhesion and integrity of the actin cytoskeleton, consistent with a role for Armadillo in cell-cell adhesive junctions. We have also used armadillo mutations to examine the effects on ovarian development of altering the stereotyped cell arrangements of the ovary. The implications of these results for the role of adhesive junctions during development are discussed.

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