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Sample records for affecting cell adhesion

  1. Cell adhesion property affected by cyclooxygenase and lipoxygenase: Opto-electric approach

    PubMed Central

    Choi, Chang Kyoung; Sukhthankar, Mugdha; Kim, Chul-Ho; Lee, Seong-Ho; English, Anthony; Kihm, Kenneth D.; Baek, Seung Joon

    2010-01-01

    Expression of cyclooxygenases (COX) and lipoxygenases (LOX) has been linked to many pathophysiological phenotypes, including cell adhesion. However, many current approaches to measure cellular changes are performed only in a fixed time point. Since cells dynamically move in conjunction with the cell matrix, there is a pressing need for dynamic or time-dependent methods for the investigation of cell properties. In the presented study, we used stable human colorectal cancer cell lines ectopically expressing COX-1, COX-2, and 15LOX-1, to investigate whether expression of COX-1, COX-2, or 15LOX-1 would affect cell adhesion using our opto-electric methodology. In a fixed time point experiment, only COX-1- and COX-2-expressing cells enhanced phosphorylation of focal adhesion kinase, but all the transfected cells showed invasion activity. However, in a real-time experiment using opto-electric approaches, transmitted cellular morphology was much different with tight adhesion being shown in COX-2 expressing cells, as imaged by differential interference contrast microscopy (DICM) and interference reflection contrast microscopy (IRCM). Furthermore, micro-impedance measurements showed a continued increase in both resistance and reactance of COX- and LOX-transfected cells, consistent with the imaging data. Our data indicate that both COX- and LOX-expressing cells have strong cell-to-cell and cell-to-substrate adhesions, and that cell imaging analysis with cell impedance data generates fully reliable results on cell adhesion measurement. PMID:20026301

  2. Cell adhesion property affected by cyclooxygenase and lipoxygenase: Opto-electric approach.

    PubMed

    Choi, Chang Kyoung; Sukhthankar, Mugdha; Kim, Chul-Ho; Lee, Seong-Ho; English, Anthony; Kihm, Kenneth D; Baek, Seung Joon

    2010-01-15

    Expression of cyclooxygenases (COX) and lipoxygenases (LOX) has been linked to many pathophysiological phenotypes, including cell adhesion. However, many current approaches to measure cellular changes are performed only in a fixed-time point. Since cells dynamically move in conjunction with the cell matrix, there is a pressing need for dynamic or time-dependent methods for the investigation of cell properties. In the presented study, we used stable human colorectal cancer cell lines ectopically expressing COX-1, COX-2, and 15LOX-1, to investigate whether expression of COX-1, COX-2, or 15LOX-1 would affect cell adhesion using our opto-electric methodology. In a fixed-time point experiment, only COX-1- and COX-2-expressing cells enhanced phosphorylation of focal adhesion kinase, but all the transfected cells showed invasion activity. However, in a real-time experiment using opto-electric approaches, transmitted cellular morphology was much different with tight adhesion being shown in COX-2 expressing cells, as imaged by differential interference contrast microscopy (DICM) and interference reflection contrast microscopy (IRCM). Furthermore, micro-impedance measurements showed a continued increase in both resistance and reactance of COX- and LOX-transfected cells, consistent with the imaging data. Our data indicate that both COX- and LOX-expressing cells have strong cell-to-cell and cell-to-substrate adhesions, and that cell imaging analysis with cell impedance data generates fully reliable results on cell adhesion measurement. Copyright 2009 Elsevier Inc. All rights reserved.

  3. [Mechanism of insulin-like growth factor-I affecting adhesion of trophoblast cells in vitro].

    PubMed

    Liu, Jie; Zhang, Han-wang; Wei, Yu-lan; Li, Yu-feng

    2005-06-01

    To investigate the mechanism of insulin-like growth factor-I (IGF-I) affecting adhesion of trophoblast cells in vitro. Trophoblast cells were obtained from early gestation at artificial abortion to set up the in vitro trophoblast cell adhesion model. The trophoblast cells were incubated with or without 10 nmol/L IGF-I and were divided into three groups (10 nmol/L IGF-I, 10 nmol/L IGF-I + alpha v beta3Ab, and control). The amount of adhered cells was assessed by examining absorbency using enzyme-linked immunoassay. Morphological changes were studied using scanning electron microscopy. The expression of phosphorylated focal adhesion kinase was determined by immunocytochemistry. After serum-starved trophoblast cells were incubated only with IGF-I, the mean absorbency was 0.491 +/- 0.049, obviously higher than control 0.198 +/- 0.022 and the difference was dramatic (P < 0.01). When cells were pre-treated with antibody against alpha v beta3 integrin and then incubated with IGF-I, the mean absorbency was only 0.184 +/- 0.031, distinctly lower than that incubated with IGF-I, and the difference was significant (P < 0.01), however, compared with control, there was no significant difference (P > 0.05). Scanning electron microscopy highlighted a dramatic increase in lamellipodial formation and extension in the IGF-I treated cells compared with control. Immunocytochemistry staining showed phosphorylated focal adhesion kinase was expressed in the trophoblast cells treated with IGF-I. 10 nmol/L IGF-I can significantly stimulate trophoblast cells adhesion to fibronectin, but antibody against alpha v beta3 integrin obviously blocks its adhesion. IGF-I can stimulate lamellipodial formation and extension at the adhesion sites, and promote adhesion of trophoblast cells to fibronectin by activating phosphorylated focal adhesion kinase.

  4. Cell surface alpha 2,6 sialylation affects adhesion of breast carcinoma cells.

    PubMed

    Lin, Shaoqiang; Kemmner, Wolfgang; Grigull, Sabine; Schlag, Peter M

    2002-05-15

    Tumor-associated alterations of cell surface glycosylation play a crucial role in the adhesion and metastasis of carcinoma cells. The aim of this study was to examine the effect of alpha 2,6-sialylation on the adhesion properties of breast carcinoma cells. To this end mammary carcinoma cells, MDA-MB-435, were sense-transfected with sialyltransferase ST6Gal-I cDNA or antisense-transfected with a part of the ST6Gal-I sequence. Sense transfectants showed an enhanced ST6Gal-I mRNA expression and enzyme activity and an increased binding of the lectin Sambucus nigra agglutinin (SNA), specific for alpha 2,6-linked sialic acid. Transfection with ST6Gal-I in the antisense direction resulted in less enzyme activity and SNA reactivity. A sense-transfected clone carrying increased amounts of alpha 2,6-linked sialic acid adhered preferentially to collagen IV and showed reduced cell-cell adhesion and enhanced invasion capacity. In contrast, antisense transfection led to less collagen IV adhesion but enhanced homotypic cell-cell adhesion. In another approach, inhibition of ST6Gal-I enzyme activity by application of soluble antisense-oligodeoxynucleotides was studied. Antisense treatment resulted in reduced ST6 mRNA expression and cell surface 2,6-sialylation and significantly decreased collagen IV adhesion. Our results suggest that cell surface alpha 2,6-sialylation contributes to cell-cell and cell-extracellular matrix adhesion of tumor cells. Inhibition of sialytransferase ST6Gal-I by antisense-oligodeoxynucleotides might be a way to reduce the metastatic capacity of carcinoma cells.

  5. Knockdown of fucosyltransferase III disrupts the adhesion of circulating cancer cells to E-selectin without affecting hematopoietic cell adhesion.

    PubMed

    Yin, Xiaoyan; Rana, Kuldeepsinh; Ponmudi, Varun; King, Michael R

    2010-11-02

    Adhesive interactions between selectins and their ligands play an essential role during cancer extravasation. Fucosylation of these proteins by fucosyltransferases, or FUTs, is critical for their functions. Using quantitative RT-PCR, we demonstrated that FUT4 and FUT7 are the predominant FUTs expressed in hematopoietic cell line, while FUT3 is heavily expressed by multiple cancer cell lines including the prostate cancer cell line MDA PCa2b. Knockdown of FUT3 expression in MDA PCa2b cells by small interference RNA (siRNA) significantly reduced FUT3 expression. Cell-surface sialyl Lewis antigens were largely abolished. Cell adhesion and cell rolling on the blood vessel wall were simulated by perfusing cancer cells through microtubes coated with recombinant human E-selectin. At physiological levels of wall shear stress, the number of flowing cancer cells recruited to the microtube surface was dramatically reduced by FUT3 knockdown. Higher rolling velocity was also observed, which is consistent with reduced E-selectin binding activity. Interestingly, FUT3 siRNA treatment also significantly reduced the cell growth rate. Combined with the novel siRNA delivery platform recently developed in our laboratory, FUT3 siRNA could be a promising conjunctive therapy aiming at reducing the metastatic virulence of circulating epithelial cancer cells.

  6. Tenascin-C enhances pancreatic cancer cell growth and motility and affects cell adhesion through activation of the integrin pathway.

    PubMed

    Paron, Igor; Berchtold, Sonja; Vörös, Julia; Shamarla, Madhavi; Erkan, Mert; Höfler, Heinz; Esposito, Irene

    2011-01-01

    Pancreatic cancer (PDAC) is characterized by an abundant fibrous tissue rich in Tenascin-C (TNC), a large ECM glycoprotein mainly synthesized by pancreatic stellate cells (PSCs). In human pancreatic tissues, TNC expression increases in the progression from low-grade precursor lesions to invasive cancer. Aim of this study was the functional characterization of the effects of TNC on biologic relevant properties of pancreatic cancer cells. Proliferation, migration and adhesion assays were performed on pancreatic cancer cell lines treated with TNC or grown on a TNC-rich matrix. Stable transfectants expressing the large TNC splice variant were generated to test the effects of endogenous TNC. TNC-dependent integrin signaling was investigated by immunoblotting, immunofluorescence and pharmacological inhibition. Endogenous TNC promoted pancreatic cancer cell growth and migration. A TNC-rich matrix also enhanced migration as well as the adhesion to the uncoated growth surface of poorly differentiated cell lines. In contrast, adhesion to fibronectin was significantly decreased in the presence of TNC. The effects of TNC on cell adhesion were paralleled by changes in the activation state of paxillin and Akt. TNC affects proliferation, migration and adhesion of poorly differentiated pancreatic cancer cell lines and might therefore play a role in PDAC spreading and metastasis in vivo.

  7. Adhesive ligand tether length affects the size and length of focal adhesions and influences cell spreading and attachment

    PubMed Central

    Attwood, Simon J.; Cortes, Ernesto; Haining, Alexander William M.; Robinson, Benjamin; Li, Danyang; Gautrot, Julien; del Río Hernández, Armando

    2016-01-01

    Cells are known to respond to physical cues from their microenvironment such as matrix rigidity. Discrete adhesive ligands within flexible strands of fibronectin connect cell surface integrins to the broader extracellular matrix and are thought to mediate mechanosensing through the cytoskeleton-integrin-ECM linkage. We set out to determine if adhesive ligand tether length is another physical cue that cells can sense. Substrates were covalently modified with adhesive arginylglycylaspartic acid (RGD) ligands coupled with short (9.5 nm), medium (38.2 nm) and long (318 nm) length inert polyethylene glycol tethers. The size and length of focal adhesions of human foreskin fibroblasts gradually decreased from short to long tethers. Furthermore, we found cell adhesion varies in a linker length dependent manner with a remarkable 75% reduction in the density of cells on the surface and a 50% reduction in cell area between the shortest and longest linkers. We also report the interplay between RGD ligand concentration and tether length in determining cellular spread area. Our findings show that without varying substrate rigidity or ligand density, tether length alone can modulate cellular behaviour. PMID:27686622

  8. Adhesive ligand tether length affects the size and length of focal adhesions and influences cell spreading and attachment

    NASA Astrophysics Data System (ADS)

    Attwood, Simon J.; Cortes, Ernesto; Haining, Alexander William M.; Robinson, Benjamin; Li, Danyang; Gautrot, Julien; Del Río Hernández, Armando

    2016-09-01

    Cells are known to respond to physical cues from their microenvironment such as matrix rigidity. Discrete adhesive ligands within flexible strands of fibronectin connect cell surface integrins to the broader extracellular matrix and are thought to mediate mechanosensing through the cytoskeleton-integrin-ECM linkage. We set out to determine if adhesive ligand tether length is another physical cue that cells can sense. Substrates were covalently modified with adhesive arginylglycylaspartic acid (RGD) ligands coupled with short (9.5 nm), medium (38.2 nm) and long (318 nm) length inert polyethylene glycol tethers. The size and length of focal adhesions of human foreskin fibroblasts gradually decreased from short to long tethers. Furthermore, we found cell adhesion varies in a linker length dependent manner with a remarkable 75% reduction in the density of cells on the surface and a 50% reduction in cell area between the shortest and longest linkers. We also report the interplay between RGD ligand concentration and tether length in determining cellular spread area. Our findings show that without varying substrate rigidity or ligand density, tether length alone can modulate cellular behaviour.

  9. Adhesive ligand tether length affects the size and length of focal adhesions and influences cell spreading and attachment.

    PubMed

    Attwood, Simon J; Cortes, Ernesto; Haining, Alexander William M; Robinson, Benjamin; Li, Danyang; Gautrot, Julien; Del Río Hernández, Armando

    2016-09-30

    Cells are known to respond to physical cues from their microenvironment such as matrix rigidity. Discrete adhesive ligands within flexible strands of fibronectin connect cell surface integrins to the broader extracellular matrix and are thought to mediate mechanosensing through the cytoskeleton-integrin-ECM linkage. We set out to determine if adhesive ligand tether length is another physical cue that cells can sense. Substrates were covalently modified with adhesive arginylglycylaspartic acid (RGD) ligands coupled with short (9.5 nm), medium (38.2 nm) and long (318 nm) length inert polyethylene glycol tethers. The size and length of focal adhesions of human foreskin fibroblasts gradually decreased from short to long tethers. Furthermore, we found cell adhesion varies in a linker length dependent manner with a remarkable 75% reduction in the density of cells on the surface and a 50% reduction in cell area between the shortest and longest linkers. We also report the interplay between RGD ligand concentration and tether length in determining cellular spread area. Our findings show that without varying substrate rigidity or ligand density, tether length alone can modulate cellular behaviour.

  10. Anabolic androgens affect the competitive interactions in cell migration and adhesion between normal mouse urothelial cells and urothelial carcinoma cells.

    PubMed

    Huang, Chi-Ping; Hsieh, Teng-Fu; Chen, Chi-Cheng; Hung, Xiao-Fan; Yu, Ai-Lin; Chang, Chawnshang; Shyr, Chih-Rong

    2014-09-26

    The urothelium is constantly rebuilt by normal urothelial cells to regenerate damaged tissues caused by stimuli in urine. However, the urothelial carcinoma cells expand the territory by aberrant growth of tumor cells, which migrate and occupy the damaged tissues to spread outside and disrupt the normal cells and organized tissues and form a tumor. Therefore, the interaction between normal urothelial cells and urothelial carcinoma cells affect the initiation and progression of urothelial tumors if normal urothelial cells fail to migrate and adhere to the damages sites to regenerate the tissues. Here, comparing normal murine urothelial cells with murine urothelial carcinoma cells (MBT-2), we found that normal cells had less migration ability than carcinoma cells. And in our co-culture system we found that carcinoma cells had propensity migrating toward normal urothelial cells and carcinoma cells had more advantages to adhere than normal cells. To reverse this condition, we used anabolic androgen, dihyrotestosterone (DHT) to treat normal cells and found that DHT treatment increased the migration ability of normal urothelial cells toward carcinoma cells and the adhesion capacity in competition with carcinoma cells. This study provides the base of a novel therapeutic approach by using anabolic hormone-enforced normal urothelial cells to regenerate the damage urothelium and defend against the occupancy of carcinoma cells to thwart cancer development and recurrence.

  11. Nanoscale topographic changes on sterilized glass surfaces affect cell adhesion and spreading.

    PubMed

    Wittenburg, Gretel; Lauer, Günter; Oswald, Steffen; Labudde, Dirk; Franz, Clemens M

    2014-08-01

    Producing sterile glass surfaces is of great importance for a wide range of laboratory and medical applications, including in vitro cell culture and tissue engineering. However, sterilization may change the surface properties of glass and thereby affect its use for medical applications, for instance as a substrate for culturing cells. To investigate potential effects of sterilization on glass surface topography, borosilicate glass coverslips were left untreated or subjected to several common sterilization procedures, including low-temperature plasma gas, gamma irradiation and steam. Imaging by atomic force microscopy demonstrated that the surface of untreated borosilicate coverslips features a complex landscape of microislands ranging from 1000 to 3000 nm in diameter and 1 to 3 nm in height. Steam treatment completely removes these microislands, producing a nanosmooth glass surface. In contrast, plasma treatment partially degrades the microisland structure, while gamma irradiation has no effect on microisland topography. To test for possible effects of the nanotopographic structures on cell adhesion, human gingival fibroblasts were seeded on untreated or sterilized glass surfaces. Analyzing fibroblast adhesion 3, 6, and 24 h after cell seeding revealed significant differences in cell attachment and spreading depending on the sterilization method applied. Furthermore, single-cell force spectroscopy revealed a connection between the nanotopographic landscape of glass and the formation of cellular adhesion forces, indicating that fibroblasts generally adhere weakly to nanosmooth but strongly to nanorough glass surfaces. Nanotopographic changes induced by different sterilization methods may therefore need to be considered when preparing sterile glass surfaces for cell culture or biomedical applications. © 2013 Wiley Periodicals, Inc.

  12. Secretagogin affects insulin secretion in pancreatic β-cells by regulating actin dynamics and focal adhesion

    PubMed Central

    Yang, Seo-Yun; Lee, Jae-Jin; Lee, Jin-Hee; Lee, Kyungeun; Oh, Seung Hoon; Lim, Yu-Mi; Lee, Myung-Shik; Lee, Kong-Joo

    2016-01-01

    Secretagogin (SCGN), a Ca2+-binding protein having six EF-hands, is selectively expressed in pancreatic β-cells and neuroendocrine cells. Previous studies suggested that SCGN enhances insulin secretion by functioning as a Ca2+-sensor protein, but the underlying mechanism has not been elucidated. The present study explored the mechanism by which SCGN enhances glucose-induced insulin secretion in NIT-1 insulinoma cells. To determine whether SCGN influences the first or second phase of insulin secretion, we examined how SCGN affects the kinetics of insulin secretion in NIT-1 cells. We found that silencing SCGN suppressed the second phase of insulin secretion induced by glucose and H2O2, but not the first phase induced by KCl stimulation. Recruitment of insulin granules in the second phase of insulin secretion was significantly impaired by knocking down SCGN in NIT-1 cells. In addition, we found that SCGN interacts with the actin cytoskeleton in the plasma membrane and regulates actin remodelling in a glucose-dependent manner. Since actin dynamics are known to regulate focal adhesion, a critical step in the second phase of insulin secretion, we examined the effect of silencing SCGN on focal adhesion molecules, including FAK (focal adhesion kinase) and paxillin, and the cell survival molecules ERK1/2 (extracellular-signal-regulated kinase 1/2) and Akt. We found that glucose- and H2O2-induced activation of FAK, paxillin, ERK1/2 and Akt was significantly blocked by silencing SCGN. We conclude that SCGN controls glucose-stimulated insulin secretion and thus may be useful in the therapy of Type 2 diabetes. PMID:27095850

  13. Parameters affecting the adhesion strength between a living cell and a colloid probe when measured by the atomic force microscope.

    PubMed

    McNamee, Cathy E; Pyo, Nayoung; Tanaka, Saaya; Vakarelski, Ivan U; Kanda, Yoichi; Higashitani, Ko

    2006-03-15

    In this study, we used the colloid probe atomic force microscopy (AFM) technique to investigate the adhesion force between a living cell and a silica colloid particle in a Leibovitz's L-15 medium (L-15). The L-15 liquid maintained the pharmaceutical conditions necessary to keep the cells alive in the outside environment during the AFM experiment. The force curves in such a system showed a steric repulsion in the compression force curve, due to the compression of the cells by the colloid probe, and an adhesion force in the decompression force curve, due to binding events between the cell and the probe. We also investigated for the first time how the position on the cell surface, the strength of the pushing force, and the residence time of the probe at the cell surface individually affected the adhesion force between a living cell and a 6.84 microm diameter silica colloid particle in L-15. The position of measuring the force on the cell surface was seen not to affect the value of the maximum adhesion force. The loading force was also seen not to notably affect the value of the maximum adhesion force, if it was small enough not to pierce and damage the cell. The residence time of the probe at the cell surface, however, clearly affected the adhesion force, where a longer residence time gave a larger maximum force. From these results, we could conclude that the AFM force measurements should be made using a loading force small enough not to damage the cell and a fixed residence time, when comparing results of different systems.

  14. Modification of Cellular Cholesterol Content Affects Traction Force, Adhesion and Cell Spreading.

    PubMed

    Norman, Leann L; Oetama, Ratna J; Dembo, Micah; Byfield, F; Hammer, Daniel A; Levitan, Irena; Aranda-Espinoza, Helim

    2010-06-01

    Cellular cholesterol is a critical component of the plasma membrane, and plays a key role in determining the physical properties of the lipid bilayer, such as elasticity, viscosity, and permeability. Surprisingly, it has been shown that cholesterol depletion increases cell stiffness, not due to plasma membrane stiffening, but rather, due to the interaction between the actin cytoskeleton and the plasma membrane. This indicates that traction stresses of the acto-myosin complex likely increase during cholesterol depletion. Here we use force traction microscopy to quantify the forces individual cells are exerting on the substrate, and total internal reflection fluorescence microscopy as well as interference reflection microscopy to observe cell-substrate adhesion and spreading. We show that single cells depleted of cholesterol produce larger traction forces and have large focal adhesions compared to untreated or cholesterol-enriched cells. Cholesterol depletion also causes a decrease in adhesion area for both single cells and monolayers. Spreading experiments illustrate a decrease in spreading area for cholesterol-depleted cells, and no effect on cholesterol-enriched cells. These results demonstrate that cholesterol plays an important role in controlling and regulating the cell-substrate interactions through the actin-plasma membrane complex, cell-cell adhesion, and spreading.

  15. Plakophilin 2 Affects Cell Migration by Modulating Focal Adhesion Dynamics and Integrin Protein Expression

    PubMed Central

    Koetsier, Jennifer L.; Amargo, Evangeline V.; Todorović, Viktor; Green, Kathleen J.; Godsel, Lisa M.

    2014-01-01

    Plakophilin 2 (PKP2), a desmosome component, modulates the activity and localization of the small GTPase RhoA at sites of cell–cell contact. PKP2 regulates cortical actin rearrangement during junction formation, and its loss is accompanied by an increase in actin stress fibers. We hypothesized that PKP2 may regulate focal adhesion dynamics and cell migration. Here we show that PKP2-deficient cells bind efficiently to the extracellular matrix, but upon spreading display total cell areas ~30% smaller than control cells. Focal adhesions in PKP2-deficient cells are ~2× larger and more stable than in control cells, and vinculin displays an increased time for fluorescence recovery after photobleaching. Furthermore, β4 and β1 integrin protein and mRNA expression is elevated in PKP2-silenced cells. Normal focal adhesion phenotypes can be restored in PKP2-null cells by dampening the RhoA pathway or silencing β1 integrin. However, integrin expression levels are not restored by RhoA signaling inhibition. These data uncover a potential role for PKP2 upstream of β1 integrin and RhoA in integrating cell–cell and cell–substrate contact signaling in basal keratinocytes necessary for the morphogenesis, homeostasis, and reepithelialization of the stratified epidermis. PMID:23884246

  16. Chemical and physical modifications to poly(dimethylsiloxane) surfaces affect adhesion of Caco-2 cells.

    PubMed

    Wang, Lin; Sun, Bing; Ziemer, Katherine S; Barabino, Gilda A; Carrier, Rebecca L

    2010-06-15

    Polydimethylsiloxane (PDMS) silicone elastomer is extensively used in soft lithography processes to fabricate microscale or nano scale systems for microfluidic or cell culture applications. Though PDMS is biocompatible, it is not an ideal material for cell culture due to its poor cell adhesion properties. In this study, PDMS surfaces were modified to promote intestinal cell adhesion, in the interest of testing feasibility of using microfabricated PDMS systems for high throughput drug screening. Modification techniques included changing chemical composition of PDMS (i.e., varying curing to mixing agent ratio, and oxidization of PDMS surface by oxygen plasma), surface treatment of PDMS by coating with charged molecules (i.e., poly-D-lysine, L-alpha-phosphatidylcholine, and a layer bylayer coating), and deposition of extracellular matrix (ECM) proteins (i.e., laminin, fibronectin, and collagen). The influence of these modifications on PDMS properties, including elastic modulus and surface properties (wettability, chemical composition, topography, and protein adsorption) were characterized. Modification techniques were all found to change PDMS properties and influence the attachment and proliferation of Caco-2 cells over three days of culture to varying degrees. Generally, Caco-2 cells preferred to attach on collagen-coated, fibronectin-coated, and fibronectin-coated oxygen-plasma treated PDMS. The results highlight the importance of considering multiple physical and chemical factors that may be influenced by biomaterial modification and result in altered cell attachment to microfabricated systems, including surface hydrophobicity, chemical composition, stiffness, and topography. This study provides a foundation for further miniaturization, utilizing soft lithography techniques, of Caco-2 cell-based system for high-throughput screening of drug intestinal absorption during lead optimization in drug discovery. The understanding of different surface modifications on

  17. Amyloid β induces adhesion of erythrocytes to endothelial cells and affects endothelial viability and functionality.

    PubMed

    Nakagawa, Kiyotaka; Kiko, Takehiro; Kuriwada, Satoko; Miyazawa, Taiki; Kimura, Fumiko; Miyazawa, Teruo

    2011-01-01

    It has been suggested that amyloid β-peptide (Aβ) might mediate the adhesion of erythrocytes to the endothelium which could disrupt the properties of endothelial cells. We provide evidence here that Aβ actually induced the binding of erythrocytes to endothelial cells and decreased endothelial viability, perhaps by the generation of oxidative and inflammatory stress. These changes are likely to contribute to the pathogenesis of Alzheimer's disease.

  18. Aire knockdown in medullary thymic epithelial cells affects Aire protein, deregulates cell adhesion genes and decreases thymocyte interaction.

    PubMed

    Pezzi, Nicole; Assis, Amanda Freire; Cotrim-Sousa, Larissa Cotrim; Lopes, Gabriel Sarti; Mosella, Maritza Salas; Lima, Djalma Sousa; Bombonato-Prado, Karina F; Passos, Geraldo Aleixo

    2016-09-01

    We demonstrate that even a partial reduction of Aire mRNA levels by siRNA-induced Aire knockdown (Aire KD) has important consequences to medullary thymic epithelial cells (mTECs). Aire knockdown is sufficient to reduce Aire protein levels, impair its nuclear location, and cause an imbalance in large-scale gene expression, including genes that encode cell adhesion molecules. These genes drew our attention because adhesion molecules are implicated in the process of mTEC-thymocyte adhesion, which is critical for T cell development and the establishment of central self-tolerance. Accordingly, we consider the following: 1) mTECs contribute to the elimination of self-reactive thymocytes through adhesion; 2) Adhesion molecules play a crucial role during physical contact between these cells; and 3) Aire is an important transcriptional regulator in mTECs. However, its role in controlling mTEC-thymocyte adhesion remains unclear. Because Aire controls adhesion molecule genes, we hypothesized that the disruption of its expression could influence mTEC-thymocyte interaction. To test this hypothesis, we used a murine Aire(+) mTEC cell line as a model system to reproduce mTEC-thymocyte adhesion in vitro. Transcriptome analysis of the mTEC cell line revealed that Aire KD led to the down-modulation of more than 800 genes, including those encoding for proteins involved in cell adhesion, i.e., the extracellular matrix constituent Lama1, the CAM family adhesion molecules Vcam1 and Icam4, and those that encode peripheral tissue antigens. Thymocytes co-cultured with Aire KD mTECs had a significantly reduced capacity to adhere to these cells. This finding is the first direct evidence that Aire also plays a role in controlling mTEC-thymocyte adhesion.

  19. Cleavage of extracellular matrix in periodontitis: gingipains differentially affect cell adhesion activities of fibronectin and tenascin-C

    PubMed Central

    Ruggiero, Sabrina; Cosgarea, Raluca; Potempa, Jan; Potempa, Barbara; Eick, Sigrun; Chiquet, Matthias

    2014-01-01

    Gingipains are cysteine proteases that represent major virulence factors of the periodontopathogenic bacterium Porphyromonas gingivalis. Gingipains are reported to degrade extracellular matrix (ECM) of periodontal tissues, leading to tissue destruction and apoptosis. The exact mechanism is not known, however. Fibronectin and tenascin-C are pericellular ECM glycoproteins present in periodontal tissues. Whereas fibronectin mediates fibroblast adhesion, tenascin-C binds to fibronectin and inhibits its cell-spreading activity. Using purified proteins in vitro, we asked whether fibronectin and tenascin-C are cleaved by gingipains at clinically relevant concentrations, and how fragmentation by the bacterial proteases affects their biological activity in cell adhesion. Fibronectin was cleaved into distinct fragments by all three gingipains; however, only arginine-specific HRgpA and RgpB but not lysine-specific Kgp destroyed its cell-spreading activity. This result was confirmed with recombinant cell-binding domain of fibronectin. Of the two major tenascin-C splice variants, the large but not the small was a substrate for gingipains, indicating that cleavage occurred primarily in the alternatively spliced domain. Surprisingly, cleavage of large tenascin-C variant by all three gingipains generated fragments with increased anti-adhesive activity towards intact fibronectin. Fibronectin and tenascin-C fragments were detected in gingival crevicular fluid of a subset of periodontitis patients. We conclude that cleavage by gingipains directly affects the biological activity of both fibronectin and tenascin-C in a manner that might lead to increased cell detachment and loss during periodontal disease. PMID:23313574

  20. Nitrogen starvation affects bacterial adhesion to soil

    PubMed Central

    Borges, Maria Tereza; Nascimento, Antônio Galvão; Rocha, Ulisses Nunes; Tótola, Marcos Rogério

    2008-01-01

    One of the main factors limiting the bioremediation of subsoil environments based on bioaugmentation is the transport of selected microorganisms to the contaminated zones. The characterization of the physiological responses of the inoculated microorganisms to starvation, especially the evaluation of characteristics that affect the adhesion of the cells to soil particles, is fundamental to anticipate the success or failure of bioaugmentation. The objective of this study was to investigate the effect of nitrogen starvation on cell surface hydrophobicity and cell adhesion to soil particles by bacterial strains previously characterized as able to use benzene, toluene or xilenes as carbon and energy sources. The strains LBBMA 18-T (non-identified), Arthrobacter aurescens LBBMA 98, Arthrobacter oxydans LBBMA 201, and Klebsiella sp. LBBMA 204–1 were used in the experiments. Cultivation of the cells in nitrogen-deficient medium caused a significant reduction of the adhesion to soil particles by all the four strains. Nitrogen starvation also reduced significantly the strength of cell adhesion to the soil particles, except for Klebsiella sp. LBBMA 204–1. Two of the four strains showed significant reduction in cell surface hydrophobicity. It is inferred that the efficiency of bacterial transport through soils might be potentially increased by nitrogen starvation. PMID:24031246

  1. [Endothelial cell adhesion molecules].

    PubMed

    Ivanov, A N; Norkin, I A; Puchin'ian, D M; Shirokov, V Iu; Zhdanova, O Iu

    2014-01-01

    The review presents current data concerning the functional role of endothelial cell adhesion molecules belonging to different structural families: integrins, selectins, cadherins, and the immunoglobulin super-family. In this manuscript the regulatory mechanisms and factors of adhesion molecules expression and distribution on the surface of endothelial cells are discussed. The data presented reveal the importance of adhesion molecules in the regulation of structural and functional state of endothelial cells in normal conditions and in pathology. Particular attention is paid to the importance of these molecules in the processes of physiological and pathological angiogenesis, regulation of permeability of the endothelial barrier and cell transmigration.

  2. Testing the Oncogenic Relevance of Cell Adhesion and Cytosketal Genes Affected by DNA Deletions in Breast Cancer

    DTIC Science & Technology

    2010-07-01

    and hair follicle derived cells as targets for the v-rasHa oncogene in mouse skin carcinogenesis. Carcinogenesis 12, 1119–1124. Wicki, A., Lehembre, F...potential oncogenic significance of genes directly involved in cell adhesion and the cytoskeleton. The aim of this study was therefore to directly test ...expression of candidate cancer genes belonging to the cytoskeletal/cell adhesion category, (2) use these tools to test the oncogenic significance of

  3. Tumor suppressor KAI1 affects integrin {alpha}v{beta}3-mediated ovarian cancer cell adhesion, motility, and proliferation

    SciTech Connect

    Ruseva, Zlatna; Geiger, Pamina Xenia Charlotte; Hutzler, Peter; Kotzsch, Matthias; Luber, Birgit; Schmitt, Manfred; Gross, Eva; Reuning, Ute

    2009-06-10

    The tetraspanin KAI1 had been described as a metastasis suppressor in many different cancer types, a function for which associations of KAI1 with adhesion and signaling receptors of the integrin superfamily likely play a role. In ovarian cancer, integrin {alpha}v{beta}3 correlates with tumor progression and its elevation in vitro provoked enhanced cell adhesion accompanied by significant increases in cell motility and proliferation in the presence of its major ligand vitronectin. In the present study, we characterized integrin {alpha}v{beta}3-mediated tumor biological effects as a function of cellular KAI1 restoration and proved for the first time that KAI1, besides its already known physical crosstalk with {beta}1-integrins, also colocalizes with integrin {alpha}v{beta}3. Functionally, elevated KAI1 levels drastically increased integrin {alpha}v{beta}3/vitronectin-dependent ovarian cancer cell adhesion. Since an intermediate level of cell adhesive strength is required for optimal cell migration, we next studied ovarian cancer cell motility as a function of KAI1 restoration. By time lapse video microscopy, we found impaired integrin {alpha}v{beta}3/vitronectin-mediated cell migration most probably due to strongly enhanced cellular immobilization onto the adhesion-supporting matrix. Moreover, KAI1 reexpression significantly diminished cell proliferation. These data strongly indicate that KAI1 may suppress ovarian cancer progression by inhibiting integrin {alpha}v{beta}3/vitronectin-provoked tumor cell motility and proliferation as important hallmarks of the oncogenic process.

  4. Synaptic Cell Adhesion Molecules in Alzheimer's Disease

    PubMed Central

    Leshchyns'ka, Iryna

    2016-01-01

    Alzheimer's disease (AD) is a neurodegenerative brain disorder associated with the loss of synapses between neurons in the brain. Synaptic cell adhesion molecules are cell surface glycoproteins which are expressed at the synaptic plasma membranes of neurons. These proteins play key roles in formation and maintenance of synapses and regulation of synaptic plasticity. Genetic studies and biochemical analysis of the human brain tissue, cerebrospinal fluid, and sera from AD patients indicate that levels and function of synaptic cell adhesion molecules are affected in AD. Synaptic cell adhesion molecules interact with Aβ, a peptide accumulating in AD brains, which affects their expression and synaptic localization. Synaptic cell adhesion molecules also regulate the production of Aβ via interaction with the key enzymes involved in Aβ formation. Aβ-dependent changes in synaptic adhesion affect the function and integrity of synapses suggesting that alterations in synaptic adhesion play key roles in the disruption of neuronal networks in AD. PMID:27242933

  5. Cell adhesion under flow.

    PubMed

    Ley, Klaus

    2009-01-01

    Cell adhesion under flow is a central function of the microcirculation during inflammation, hemostasis, and immune regulation. This special issue of Microcirculation explores the common and distinct mechanisms that myeloid cells, lymphocytes, platelets, and sickle erythrocytes use to adhere to microvascular endothelium and the underlying basement membrane structures. A common theme in these processes is the need for rapid integrin activation, often initiated by binding of ligands to their cognate G protein-coupled receptors, followed by adhesion strengthening associated with integrin redistribution and outside-in signaling. These elements have been identified for all cells tested except sickle erythrocytes.

  6. IGF-I/EGF and E2 signaling crosstalk through IGF-IR conduit point affects breast cancer cell adhesion.

    PubMed

    Voudouri, Kallirroi; Nikitovic, Dragana; Berdiaki, Aikaterini; Kletsas, Dimitris; Karamanos, Nikos K; Tzanakakis, George N

    2016-12-01

    Epidermal growth factor (EGF)/insulin like growth factor-I (IGF-I) and Estradiol (E2) can regulate biological functions of hormone-dependent tumor cells. Fibronectin (FN) is a large glycoprotein abundantly expressed in breast cancer extracellular matrices (ECMs) postulated to be a marker of aggressiveness during cancer pathogenesis. In this study we demonstrate that IGF-I/EGF as well E2 strongly increase the adhesion of the MCF-7 breast cancer cells onto FN. Moreover, IGF-IR is necessary for the IGF-I-/EGF- and E2-induced cell adhesion. Erk1/2 inhibition abolished the IGF-I-/EGF-/E2-induced MCF-7 cell adhesion, suggesting that this regulation of cell adhesion is perpetrated through Erk1/2 downstream signaling. Erk1/2 signaling was shown to modulate IGF-IR status as its' inhibition attenuates both IGF-IR expression and activation. Notably, EGF and E2 enhanced the mRNA as well as protein expression of IGF-IR in MCF-7 cells. Confocal microscopy demonstrated that treatment of MCF-7 cells with IGF-I or EGF induced actin reorganization, which was attenuated with Erk1/2 inhibition. Interestingly, IGF-I treatment induced a co-localization of IGF-IR and FAK, which was evident mostly at the cell membranes of MCF-7 cells. In summary, IGF-IR was shown to be a convergence point for the IGF-/EGF- and E2-dependent MCF-7 cell adhesion onto FN.

  7. Cadmium affects focal adhesion kinase (FAK) in mesangial cells: involvement of CaMK-II and the actin cytoskeleton.

    PubMed

    Choong, Grace; Liu, Ying; Templeton, Douglas M

    2013-08-01

    The toxic metal ion cadmium (Cd(2+)) induces pleiotropic effects on cell death and survival, in part through effects on cell signaling mechanisms and cytoskeletal dynamics. Linking these phenomena appears to be calmodulin-dependent activation of the Ca(2+)/calmodulin-dependent protein kinase II (CaMK-II). Here we show that interference with the dynamics of the filamentous actin cytoskeleton, either by stabilization or destabilization, results in disruption of focal adhesions at the ends of organized actin structures, and in particular the loss of vinculin and focal adhesion kinase (FAK) from the contacts is a result. Low-level exposure of renal mesangial cells to CdCl2 disrupts the actin cytoskeleton and recapitulates the effects of manipulation of cytoskeletal dynamics with biological agents. Specifically, Cd(2+) treatment causes loss of vinculin and FAK from focal contacts, concomitant with cytoskeletal disruption, and preservation of cytoskeletal integrity with either a calmodulin antagonist or a CaMK-II inhibitor abrogates these effects of Cd(2+). Notably, inhibition of CaMK-II decreases the migration of FAK-phosphoTyr925 to a membrane-associated compartment where it is otherwise sequestered from focal adhesions in a Cd(2+)-dependent manner. These results add further insight into the mechanism of the CaMK-II-dependent effects of Cd(2+) on cellular function. Copyright © 2013 Wiley Periodicals, Inc.

  8. Autosomal Mutations Affecting Adhesion between Wing Surfaces in Drosophila Melanogaster

    PubMed Central

    Prout, M.; Damania, Z.; Soong, J.; Fristrom, D.; Fristrom, J. W.

    1997-01-01

    Integrins are evolutionarily conserved transmembrane α,β heterodimeric receptors involved in cell-to-matrix and cell-to-cell adhesions. In Drosophila the position-specific (PS) integrins mediate the formation and maintenance of junctions between muscle and epidermis and between the two epidermal wing surfaces. Besides integrins, other proteins are implicated in integrin-dependent adhesion. In Drosophila, somatic clones of mutations in PS integrin genes disrupt adhesion between wing surfaces to produce wing blisters. To identify other genes whose products function in adhesion between wing surfaces, we conducted a screen for autosomal mutations that produce blisters in somatic wing clones. We isolated 76 independent mutations in 25 complementation groups, 15 of which contain more than one allele. Chromosomal sites were determined by deficiency mapping, and genetic interactions with mutations in the β(PS) integrin gene myospheroid were investigated. Mutations in four known genes (blistered, Delta, dumpy and mastermind) were isolated. Mutations were isolated in three new genes (piopio, rhea and steamer duck) that affect myo-epidermal junctions or muscle function in embryos. Mutations in three other genes (kakapo, kiwi and moa) may also affect cell adhesion or muscle function at hatching. These new mutants provide valuable material for the study of integrin-dependent cell-to-cell adhesion. PMID:9136017

  9. Autosomal mutations affecting adhesion between wing surfaces in Drosophila melanogaster.

    PubMed

    Prout, M; Damania, Z; Soong, J; Fristrom, D; Fristrom, J W

    1997-05-01

    Integrins are evolutionarily conserved transmembrane alpha,beta heterodimeric receptors involved in cell-to-matrix and cell-to-cell adhesions. In Drosophila the position-specific (PS) integrins mediate the formation and maintenance of junctions between muscle and epidermis and between the two epidermal wing surfaces. Besides integrins, other proteins are implicated in integrin-dependent adhesion. In Drosophila, somatic clones of mutations in PS integrin genes disrupt adhesion between wing surfaces to produce wing blisters. To identify other genes whose products function in adhesion between wing surfaces, we conducted a screen for autosomal mutations that produce blisters in somatic wing clones. We isolated 76 independent mutations in 25 complementation groups, 15 of which contain more than one allele. Chromosomal sites were determined by deficiency mapping, and genetic interactions with mutations in the beta PS integrin gene myospheroid were investigated. Mutations in four known genes (blistered, Delta, dumpy and mastermind) were isolated. Mutations were isolated in three new genes (piopio, rhea and steamer duck) that affect myo-epidermal junctions or muscle function in embryos. Mutations in three other genes (kakapo, kiwi and moa) may also affect cell adhesion or muscle function at hatching. These new mutants provide valuable material for the study of integrin-dependent cell-to-cell adhesion.

  10. Mapping cell surface adhesion by rotation tracking and adhesion footprinting

    PubMed Central

    Li, Isaac T. S.; Ha, Taekjip; Chemla, Yann R.

    2017-01-01

    Rolling adhesion, in which cells passively roll along surfaces under shear flow, is a critical process involved in inflammatory responses and cancer metastasis. Surface adhesion properties regulated by adhesion receptors and membrane tethers are critical in understanding cell rolling behavior. Locally, adhesion molecules are distributed at the tips of membrane tethers. However, how functional adhesion properties are globally distributed on the individual cell’s surface is unknown. Here, we developed a label-free technique to determine the spatial distribution of adhesive properties on rolling cell surfaces. Using dark-field imaging and particle tracking, we extract the rotational motion of individual rolling cells. The rotational information allows us to construct an adhesion map along the contact circumference of a single cell. To complement this approach, we also developed a fluorescent adhesion footprint assay to record the molecular adhesion events from cell rolling. Applying the combination of the two methods on human promyelocytic leukemia cells, our results surprisingly reveal that adhesion is non-uniformly distributed in patches on the cell surfaces. Our label-free adhesion mapping methods are applicable to the variety of cell types that undergo rolling adhesion and provide a quantitative picture of cell surface adhesion at the functional and molecular level. PMID:28290531

  11. Mapping cell surface adhesion by rotation tracking and adhesion footprinting

    NASA Astrophysics Data System (ADS)

    Li, Isaac T. S.; Ha, Taekjip; Chemla, Yann R.

    2017-03-01

    Rolling adhesion, in which cells passively roll along surfaces under shear flow, is a critical process involved in inflammatory responses and cancer metastasis. Surface adhesion properties regulated by adhesion receptors and membrane tethers are critical in understanding cell rolling behavior. Locally, adhesion molecules are distributed at the tips of membrane tethers. However, how functional adhesion properties are globally distributed on the individual cell’s surface is unknown. Here, we developed a label-free technique to determine the spatial distribution of adhesive properties on rolling cell surfaces. Using dark-field imaging and particle tracking, we extract the rotational motion of individual rolling cells. The rotational information allows us to construct an adhesion map along the contact circumference of a single cell. To complement this approach, we also developed a fluorescent adhesion footprint assay to record the molecular adhesion events from cell rolling. Applying the combination of the two methods on human promyelocytic leukemia cells, our results surprisingly reveal that adhesion is non-uniformly distributed in patches on the cell surfaces. Our label-free adhesion mapping methods are applicable to the variety of cell types that undergo rolling adhesion and provide a quantitative picture of cell surface adhesion at the functional and molecular level.

  12. Notch-Mediated Cell Adhesion

    PubMed Central

    Murata, Akihiko; Hayashi, Shin-Ichi

    2016-01-01

    Notch family members are generally recognized as signaling molecules that control various cellular responses in metazoan organisms. Early fly studies and our mammalian studies demonstrated that Notch family members are also cell adhesion molecules; however, information on the physiological roles of this function and its origin is limited. In this review, we discuss the potential present and ancestral roles of Notch-mediated cell adhesion in order to explore its origin and the initial roles of Notch family members dating back to metazoan evolution. We hypothesize that Notch family members may have initially emerged as cell adhesion molecules in order to mediate multicellularity in the last common ancestor of metazoan organisms. PMID:26784245

  13. Mechanics of Nascent Cell Adhesions

    NASA Astrophysics Data System (ADS)

    Mejean, Cecile O.; Schaefer, Andrew W.; Forscher, Paul; Dufresne, Eric R.

    2009-03-01

    Cells have the ability to sense and respond to mechanical and biochemical cues from their environment. In neurons, the binding and restraint of transmembrane cell adhesion molecules (CAMs) can trigger acute periods of axon growth. Preceding growth, the cell must create a stiff mechanical linkage between the CAM and the cytoskeleton. Using holographic optical tweezers, we manipulate CAM-coated beads on the membrane of the cell. We investigate the dynamics of the mechanical properties of this linkage as a function of time, applied force, and CAM density. We find that CAM-coated beads exhibit stochastic intermittent binding to the cytoskeleton. In time, we observed that the adhesions stiffen and their mechanical properties depend on the applied force. Treatment of cells with small molecules that alter cytoskeletal dynamics are used to probe the roles of actin filament assembly and myosin motor activity in adhesion formation.

  14. Cell adhesion: integrating cytoskeletal dynamics and cellular tension

    PubMed Central

    Parsons, J. Thomas; Horwitz, Alan Rick; Schwartz, Martin A.

    2010-01-01

    Cell migration affects all morphogenetic processes and contributes to numerous diseases, including cancer and cardiovascular disease. For most cells in most environments, movement begins with protrusion of the cell membrane followed by the formation of new adhesions at the cell front that link the actin cytoskeleton to the substratum, generation of traction forces that move the cell forwards and disassembly of adhesions at the cell rear. Adhesion formation and disassembly drive the migration cycle by activating Rho GTPases, which in turn regulate actin polymerization and myosin II activity, and therefore adhesion dynamics. PMID:20729930

  15. Salmonella Adhesion, Invasion and Cellular Immune Responses Are Differentially Affected by Iron Concentrations in a Combined In Vitro Gut Fermentation-Cell Model

    PubMed Central

    Dostal, Alexandra; Gagnon, Mélanie; Chassard, Christophe; Zimmermann, Michael Bruce; O'Mahony, Liam; Lacroix, Christophe

    2014-01-01

    In regions with a high infectious disease burden, concerns have been raised about the safety of iron supplementation because higher iron concentrations in the gut lumen may increase risk of enteropathogen infection. The aim of this study was to investigate interactions of the enteropathogen Salmonella enterica ssp. enterica Typhimurium with intestinal cells under different iron concentrations encountered in the gut lumen during iron deficiency and supplementation using an in vitro colonic fermentation system inoculated with immobilized child gut microbiota combined with Caco-2/HT29-MTX co-culture monolayers. Colonic fermentation effluents obtained during normal, low (chelation by 2,2'-dipyridyl) and high iron (26.5 mg iron/L) fermentation conditions containing Salmonella or pure Salmonella cultures with similar iron conditions were applied to cellular monolayers. Salmonella adhesion and invasion capacity, cellular integrity and immune response were assessed. Under high iron conditions in pure culture, Salmonella adhesion was 8-fold increased compared to normal iron conditions while invasion was not affected leading to decreased invasion efficiency (−86%). Moreover, cellular cytokines IL-1β, IL-6, IL-8 and TNF-α secretion as well as NF-κB activation in THP-1 cells were attenuated under high iron conditions. Low iron conditions in pure culture increased Salmonella invasion correlating with an increase in IL-8 release. In fermentation effluents, Salmonella adhesion was 12-fold and invasion was 428-fold reduced compared to pure culture. Salmonella in high iron fermentation effluents had decreased invasion efficiency (−77.1%) and cellular TNF-α release compared to normal iron effluent. The presence of commensal microbiota and bacterial metabolites in fermentation effluents reduced adhesion and invasion of Salmonella compared to pure culture highlighting the importance of the gut microbiota as a barrier during pathogen invasion. High iron concentrations as

  16. Focal Adhesion Kinase Modulates Cell Adhesion Strengthening via Integrin Activation

    PubMed Central

    Michael, Kristin E.; Dumbauld, David W.; Burns, Kellie L.; Hanks, Steven K.

    2009-01-01

    Focal adhesion kinase (FAK) is an essential nonreceptor tyrosine kinase regulating cell migration, adhesive signaling, and mechanosensing. Using FAK-null cells expressing FAK under an inducible promoter, we demonstrate that FAK regulates the time-dependent generation of adhesive forces. During the early stages of adhesion, FAK expression in FAK-null cells enhances integrin activation to promote integrin binding and, hence, the adhesion strengthening rate. Importantly, FAK expression regulated integrin activation, and talin was required for the FAK-dependent effects. A role for FAK in integrin activation was confirmed in human fibroblasts with knocked-down FAK expression. The FAK autophosphorylation Y397 site was required for the enhancements in adhesion strengthening and integrin-binding responses. This work demonstrates a novel role for FAK in integrin activation and the time-dependent generation of cell–ECM forces. PMID:19297531

  17. Cell-Cell Adhesion and Breast Cancer.

    DTIC Science & Technology

    1998-01-01

    Staging of breast cancer. In: K.I. Bland and E.M. Copeland (eds.), The breast: Comprehensive management of benign and malignant diseases , pp. 313-330... desmosomes . The physical strength of adhesion between two cells is likely to be dependent upon a number of factors, including the number of adhesion

  18. Cell-Substrate Adhesion by Amoeboid Cells

    NASA Astrophysics Data System (ADS)

    Flanders, Bret; Panta, Krishna

    Amoeboid migration is a rapid (10 μm min-1) mode of migration that some tumor cells exhibit. To permit such rapid movement, the adhesive contacts between the cell and the substrate must be relatively short-lived and weak. In this study, we investigate the basic adhesive character of amoeboid cells (D. discoideum) in contact with silanized glass substrates. We observe the initiation and spreading of the adhesive contacts that these cells establish as they settle under gravity onto the substrate and relax towards mechanical equilibrium. The use of interference reflection microscopy and cellular tethering measurements have allowed us to determine the basic adhesive properties of the cell: the membrane-medium interfacial energy; the bending modulus; the equilibrium contact angle; and the work of adhesion. We find the time scale on which settling occurs to be longer than expected. Implications of these results on adhesion and migration will be discussed. The authors are grateful for support from NSF (CBET-1451903) and NIH (1R21EY026392).

  19. Effects of curvature and cell-cell interaction on cell adhesion in microvessels.

    PubMed

    Yan, W W; Liu, Y; Fu, B M

    2010-10-01

    It has been found that both circulating blood cells and tumor cells are more easily adherent to curved microvessels than straight ones. This motivated us to investigate numerically the effect of the curvature of the curved vessel on cell adhesion. In this study, the fluid dynamics was carried out by the lattice Boltzmann method (LBM), and the cell dynamics was governed by the Newton's law of translation and rotation. The adhesive dynamics model involved the effect of receptor-ligand bonds between circulating cells and endothelial cells (ECs). It is found that the curved vessel would increase the simultaneous bond number, and the probability of cell adhesion is increased consequently. The interaction between traveling cells would also affect the cell adhesion significantly. For two-cell case, the simultaneous bond number of the rear cell is increased significantly, and the curvature of microvessel further enhances the probability of cell adhesion.

  20. Measurement systems for cell adhesive forces.

    PubMed

    Zhou, Dennis W; García, Andrés J

    2015-02-01

    Cell adhesion to the extracellular matrix (ECM) involves integrin receptor-ligand binding and clustering to form focal adhesion (FA) complexes, which mechanically link the cell's cytoskeleton to the ECM and regulate fundamental cell signaling pathways. Although elucidation of the biochemical events in cell-matrix adhesive interactions is rapidly advancing, recent studies show that the forces underlying cell-matrix adhesive interactions are also critical to cell responses. Therefore, multiple measurement systems have been developed to quantify the spatial and temporal dynamics of cell adhesive forces, and these systems have identified how mechanical events influence cell phenotype and FA structure-function relationships under physiological and pathological settings. This review focuses on the development, methodology, and applications of measurement systems for probing (a) cell adhesion strength and (b) 2D and 3D cell traction forces.

  1. Matrine inhibits the adhesion and migration of BCG823 gastric cancer cells by affecting the structure and function of the vasodilator-stimulated phosphoprotein (VASP).

    PubMed

    Zhang, Jing-wei; Su, Ke; Shi, Wen-tao; Wang, Ying; Hu, Peng-chao; Wang, Yang; Wei, Lei; Xiang, Jin; Yang, Fang

    2013-08-01

    Vasodilator-stimulated phosphoprotein (VASP) expression is upregulated in human cancers and correlates with more invasive advanced tumor stages. The aim of this study was to elucidate the mechanisms by which matrine, an alkaloid derived from Sophora species plants, acted on the VASP protein in human gastric cancer cells in vitro. VASP was expressed and purified. Intrinsic fluorescence spectroscopy was used to study the binding of matrine to VASP. CD spectroscopy was used to examine the changes in the VASP protein secondary structure. Human gastric carcinoma cell line BGC823 was tested. Scratch wound and cell adhesion assays were used to detect the cell migration and adhesion, respectively. Real-time PCR and Western blotting assays were used to measure mRNA and protein expression of VASP. In the fluorescence assay, the dissociation constant for binding of matrine to VASP protein was 0.86 mmol/L, thus the direct binding between the two molecules was weak. However, matrine (50 μg/mL) caused obvious change in the secondary structure of VASP protein shown in CD spectrum. Treatments of BGC823 cells with matrine (50 μg/mL) significantly inhibited the cell migration and adhesion. The alkaloid changed the subcellular distribution of VASP and formation of actin stress fibers in BGC823 cells. The alkaloid caused small but statistically significant decreases in VASP protein expression and phosphorylation, but had no significant effect on VASP mRNA expression. Matrine modulates the structure, subcellular distribution, expression and phosphorylation of VASP in human gastric cancer cells, thus inhibiting the cancer cell adhesion and migration.

  2. Cell adhesion molecules and sleep.

    PubMed

    O'Callaghan, Emma Kate; Ballester Roig, Maria Neus; Mongrain, Valérie

    2017-03-01

    Cell adhesion molecules (CAMs) play essential roles in the central nervous system, where some families are involved in synaptic development and function. These synaptic adhesion molecules (SAMs) are involved in the regulation of synaptic plasticity, and the formation of neuronal networks. Recent findings from studies examining the consequences of sleep loss suggest that these molecules are candidates to act in sleep regulation. This review highlights the experimental data that lead to the identification of SAMs as potential sleep regulators, and discusses results supporting that specific SAMs are involved in different aspects of sleep regulation. Further, some potential mechanisms by which SAMs may act to regulate sleep are outlined, and the proposition that these molecules may serve as molecular machinery in the two sleep regulatory processes, the circadian and homeostatic components, is presented. Together, the data argue that SAMs regulate the neuronal plasticity that underlies sleep and wakefulness. Copyright © 2016 Elsevier Ireland Ltd and Japan Neuroscience Society. All rights reserved.

  3. High-Frequency Mechanostimulation of Cell Adhesion.

    PubMed

    Kadem, Laith F; Suana, K Grace; Holz, Michelle; Wang, Wei; Westerhaus, Hannes; Herges, Rainer; Selhuber-Unkel, Christine

    2017-01-02

    Cell adhesion is regulated by molecularly defined protein interactions and by mechanical forces, which can activate a dynamic restructuring of adhesion sites. Previous attempts to explore the response of cell adhesion to forces have been limited to applying mechanical stimuli that involve the cytoskeleton. In contrast, we here apply a new, oscillatory type of stimulus through push-pull azobenzenes. Push-pull azobenzenes perform a high-frequency, molecular oscillation upon irradiation with visible light that has frequently been applied in polymer surface relief grating. We here use these oscillations to address single adhesion receptors. The effect of molecular oscillatory forces on cell adhesion has been analyzed using single-cell force spectroscopy and gene expression studies. Our experiments demonstrate a reinforcement of cell adhesion as well as upregulated expression levels of adhesion-associated genes as a result of the nanoscale "tickling" of integrins. This novel type of mechanical stimulus provides a previously unprecedented molecular control of cellular mechanosensing.

  4. Plasma polymerization for cell adhesive/anti-adhesive implant coating

    NASA Astrophysics Data System (ADS)

    Meichsner, Juergen; Testrich, Holger; Rebl, Henrike; Nebe, Barbara

    2015-09-01

    Plasma polymerization of ethylenediamine (C2H8N2, EDA) and perfluoropropane (C3F8, PFP) with admixture of argon and hydrogen, respectively, was studied using an asymmetric 13.56 MHz CCP. The analysis of the plasma chemical gas phase processes for stable molecules revealed consecutive reactions: C2H8N2 consumption, intermediate product NH3, and main final product HCN. In C3F8- H2 plasma the precursor molecule C3F8 and molecular hydrogen are consumed and HF as well as CF4 and C2F6 are found as main gaseous reaction products. The deposited plasma polymer films on the powered electrode are strongly cross-linked due to ion bombardment. The stable plasma polymerized films from EDA are characterized by high content of nitrogen with N/C ratio of about 0.35. The plasma polymerized fluorocarbon film exhibit a reduced F/C ratio of about 1.2. Adhesion tests with human osteoblast cell line MG-63 on coated Ti6Al4V samples (polished) compared with uncoated reference sample yielded both, the enhanced cell adhesion for plasma polymerized EDA and significantly reduced cell adhesion for fluorocarbon coating, respectively. Aging of the plasma polymerized EDA film, in particular due to the reactions with oxygen from air, showed no significant change in the cell adhesion. The fluorocarbon coating with low cell adhesion is of interest for temporary implants. Funded by the Campus PlasmaMed.

  5. Cell adhesion heterogeneity reinforces tumour cell dissemination: novel insights from a mathematical model.

    PubMed

    Reher, David; Klink, Barbara; Deutsch, Andreas; Voss-Böhme, Anja

    2017-08-11

    Cancer cell invasion, dissemination, and metastasis have been linked to an epithelial-mesenchymal transition (EMT) of individual tumour cells. During EMT, adhesion molecules like E-cadherin are downregulated and the decrease of cell-cell adhesion allows tumour cells to dissociate from the primary tumour mass. This complex process depends on intracellular cues that are subject to genetic and epigenetic variability, as well as extrinsic cues from the local environment resulting in a spatial heterogeneity in the adhesive phenotype of individual tumour cells. Here, we use a novel mathematical model to study how adhesion heterogeneity, influenced by intrinsic and extrinsic factors, affects the dissemination of tumour cells from an epithelial cell population. The model is a multiscale cellular automaton that couples intracellular adhesion receptor regulation with cell-cell adhesion. Simulations of our mathematical model indicate profound effects of adhesion heterogeneity on tumour cell dissemination. In particular, we show that a large variation of intracellular adhesion receptor concentrations in a cell population reinforces cell dissemination, regardless of extrinsic cues mediated through the local cell density. However, additional control of adhesion receptor concentration through the local cell density, which can be assumed in healthy cells, weakens the effect. Furthermore, we provide evidence that adhesion heterogeneity can explain the remarkable differences in adhesion receptor concentrations of epithelial and mesenchymal phenotypes observed during EMT and might drive early dissemination of tumour cells. Our results suggest that adhesion heterogeneity may be a universal trigger to reinforce cell dissemination in epithelial cell populations. This effect can be at least partially compensated by a control of adhesion receptor regulation through neighbouring cells. Accordingly, our findings explain how both an increase in intra-tumour adhesion heterogeneity and the

  6. Cell adhesion under hydrodynamic flow conditions.

    PubMed

    Gopalan, P K; Jones, D A; McIntire, L V; Smith, C W

    2001-05-01

    This unit describes a hydrodynamic assay to study the relative importance of various receptor/ligand interactions in cell-cell and cell-substrate adhesion and to quantitate the strength of their binding. The basic protocol describes how to assemble the single-chamber flow system with the substrate, add the cells in suspension, and record the experiment on videotape. Alternate protocols present assays to determine how monoclonal antibodies and stimulating and inhibiting agents affect the substrate and the perfusing cells in suspension. Another alternate protocol details the use of the double-chamber flow system. Support protocols describe how to construct the single- and double-chamber flow systems and how to analyze the data from an experiment. Recording and analyzing the flow experiment requires the use of video equipment and, optionally, a computer and imaging software.

  7. Focal Adhesion-Independent Cell Migration.

    PubMed

    Paluch, Ewa K; Aspalter, Irene M; Sixt, Michael

    2016-10-06

    Cell migration is central to a multitude of physiological processes, including embryonic development, immune surveillance, and wound healing, and deregulated migration is key to cancer dissemination. Decades of investigations have uncovered many of the molecular and physical mechanisms underlying cell migration. Together with protrusion extension and cell body retraction, adhesion to the substrate via specific focal adhesion points has long been considered an essential step in cell migration. Although this is true for cells moving on two-dimensional substrates, recent studies have demonstrated that focal adhesions are not required for cells moving in three dimensions, in which confinement is sufficient to maintain a cell in contact with its substrate. Here, we review the investigations that have led to challenging the requirement of specific adhesions for migration, discuss the physical mechanisms proposed for cell body translocation during focal adhesion-independent migration, and highlight the remaining open questions for the future.

  8. Passively stuck: death does not affect gecko adhesion strength

    PubMed Central

    Stewart, William J.; Higham, Timothy E.

    2014-01-01

    Many geckos use adhesive toe pads on the bottom of their digits to attach to surfaces with remarkable strength. Although gecko adhesion has been studied for hundreds of years, gaps exist in our understanding at the whole-animal level. It remains unclear whether the strength and maintenance of adhesion are determined by the animal or are passively intrinsic to the system. Here we show, for the first time, that strong adhesion is produced passively at the whole-animal level. Experiments on both live and recently euthanized tokay geckos (Gekko gecko) revealed that death does not affect the dynamic adhesive force or motion of a gecko foot when pulled along a vertical surface. Using a novel device that applied repeatable and steady-increasing pulling forces to the foot in shear, we found that the adhesive force was similarly high and variable when the animal was alive (mean ± s.d. = 5.4 ± 1.7 N) and within 30 min after death (5.4 ± 2.1 N). However, kinematic analyses showed that live geckos are able to control the degree of toe pad engagement and can rapidly stop strong adhesion by hyperextending the toes. This study offers the first assessment of whole-animal adhesive force under extremely controlled conditions. Our findings reveal that dead geckos maintain the ability to adhere with the same force as living animals, disproving that strong adhesion requires active control. PMID:25472940

  9. Passively stuck: death does not affect gecko adhesion strength.

    PubMed

    Stewart, William J; Higham, Timothy E

    2014-12-01

    Many geckos use adhesive toe pads on the bottom of their digits to attach to surfaces with remarkable strength. Although gecko adhesion has been studied for hundreds of years, gaps exist in our understanding at the whole-animal level. It remains unclear whether the strength and maintenance of adhesion are determined by the animal or are passively intrinsic to the system. Here we show, for the first time, that strong adhesion is produced passively at the whole-animal level. Experiments on both live and recently euthanized tokay geckos (Gekko gecko) revealed that death does not affect the dynamic adhesive force or motion of a gecko foot when pulled along a vertical surface. Using a novel device that applied repeatable and steady-increasing pulling forces to the foot in shear, we found that the adhesive force was similarly high and variable when the animal was alive (mean ± s.d. = 5.4 ± 1.7 N) and within 30 min after death (5.4 ± 2.1 N). However, kinematic analyses showed that live geckos are able to control the degree of toe pad engagement and can rapidly stop strong adhesion by hyperextending the toes. This study offers the first assessment of whole-animal adhesive force under extremely controlled conditions. Our findings reveal that dead geckos maintain the ability to adhere with the same force as living animals, disproving that strong adhesion requires active control.

  10. Scale of Carbon Nanomaterials Affects Neural Outgrowth and Adhesion

    PubMed Central

    Franca, Eric; Jao, PitFee; Fang, Sheng-Po; Alagapan, Sankaraleengam; Pan, Liangbin; Yoon, Jung Hae; Yoon, Yong-Kyu ‘YK’

    2016-01-01

    Carbon nanomaterials have become increasingly popular microelectrode materials for neuroscience applications. Here we study how the scale of carbon nanotubes and carbon nanofibers affect neural viability, outgrowth, and adhesion. Carbon nanotubes were deposited on glass coverslips via a layer-by-layer method with polyethylenimine (PEI). Carbonized nanofibers were fabricated by electrospinning SU-8 and pyrolyzing the nanofiber depositions. Additional substrates tested were carbonized and SU-8 thin films and SU-8 nanofibers. Surfaces were O2-plasma treated, coated with varying concentrations of PEI, seeded with E18 rat cortical cells, and examined at 3, 4, and 7 days in vitro (DIV). Neural adhesion was examined at 4 DIV utilizing a parallel plate flow chamber. At 3 DIV, neural viability was lower on the nanofiber and thin film depositions treated with higher PEI concentrations which corresponded with significantly higher zeta potentials (surface charge); this significance was drastically higher on the nanofibers suggesting that the nanostructure may collect more PEI molecules, causing increased toxicity. At 7 DIV, significantly higher neurite outgrowth was observed on SU-8 nanofiber substrates with nanofibers a significant fraction of a neuron’s size. No differences were detected for carbonized nanofibers or carbon nanotubes. Both carbonized and SU-8 nanofibers had significantly higher cellular adhesion post-flow in comparison to controls whereas the carbon nanotubes were statistically similar to control substrates. These data suggest a neural cell preference for larger-scale nanomaterials with specific surface treatments. These characteristics could be taken advantage of in the future design and fabrication of neural microelectrodes. PMID:26829799

  11. Quantitative methods for analyzing cell-cell adhesion in development.

    PubMed

    Kashef, Jubin; Franz, Clemens M

    2015-05-01

    During development cell-cell adhesion is not only crucial to maintain tissue morphogenesis and homeostasis, it also activates signalling pathways important for the regulation of different cellular processes including cell survival, gene expression, collective cell migration and differentiation. Importantly, gene mutations of adhesion receptors can cause developmental disorders and different diseases. Quantitative methods to measure cell adhesion are therefore necessary to understand how cells regulate cell-cell adhesion during development and how aberrations in cell-cell adhesion contribute to disease. Different in vitro adhesion assays have been developed in the past, but not all of them are suitable to study developmentally-related cell-cell adhesion processes, which usually requires working with low numbers of primary cells. In this review, we provide an overview of different in vitro techniques to study cell-cell adhesion during development, including a semi-quantitative cell flipping assay, and quantitative single-cell methods based on atomic force microscopy (AFM)-based single-cell force spectroscopy (SCFS) or dual micropipette aspiration (DPA). Furthermore, we review applications of Förster resonance energy transfer (FRET)-based molecular tension sensors to visualize intracellular mechanical forces acting on cell adhesion sites. Finally, we describe a recently introduced method to quantitate cell-generated forces directly in living tissues based on the deformation of oil microdroplets functionalized with adhesion receptor ligands. Together, these techniques provide a comprehensive toolbox to characterize different cell-cell adhesion phenomena during development. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. van der Waals forces influencing adhesion of cells

    PubMed Central

    Kendall, K.; Roberts, A. D.

    2015-01-01

    Adhesion molecules, often thought to be acting by a ‘lock and key’ mechanism, have been thought to control the adhesion of cells. While there is no doubt that a coating of adhesion molecules such as fibronectin on a surface affects cell adhesion, this paper aims to show that such surface contamination is only one factor in the equation. Starting from the baseline idea that van der Waals force is a ubiquitous attraction between all molecules, and thereby must contribute to cell adhesion, it is clear that effects from geometry, elasticity and surface molecules must all add on to the basic cell attractive force. These effects of geometry, elasticity and surface molecules are analysed. The adhesion force measured between macroscopic polymer spheres was found to be strongest when the surfaces were absolutely smooth and clean, with no projecting protruberances. Values of the measured surface energy were then about 35 mJ m−2, as expected for van der Waals attractions between the non-polar molecules. Surface projections such as abrasion roughness or dust reduced the molecular adhesion substantially. Water cut the measured surface energy to 3.4 mJ m−2. Surface active molecules lowered the adhesion still further to less than 0.3 mJ m−2. These observations do not support the lock and key concept. PMID:25533101

  13. Cell Adhesion Molecules in Chemically-Induced Renal Injury

    PubMed Central

    Prozialeck, Walter C.; Edwards, Joshua R.

    2007-01-01

    Cell adhesion molecules are integral cell-membrane proteins that maintain cell-cell and cell-substrate adhesion, and in some cases, act as regulators of intracellular signaling cascades. In the kidney, cell adhesion molecules such as the cadherins, the catenins, ZO-1, occludin and the claudins are essential for maintaining the epithelial polarity and barrier integrity that are necessary for the normal absorption/excretion of fluid and solutes. A growing volume of evidence indicates that these cell adhesion molecules are important early targets for a variety of nephrotoxic substances including metals, drugs, and venom components. In addition, it is now widely appreciated that molecules such as ICAM-1, the integrins and selectins play important roles in the recruitment of leukocytes and inflammatory responses that are associated with nephrotoxic injury. This review summarizes the results of recent in vitro and in vivo studies indicating that these cell adhesion molecules may be primary molecular targets in many types of chemically-induced renal injury. Some of the specific agents that are discussed include Cd, Hg, Bi, cisplatin, aminoglycoside antibiotics, S-(1,2-dichlorovinyl-L-cysteine) (DCVC) and various venom toxins. This review also includes a discussion of the various mechanisms by which these substances can affect cell adhesion molecules in the kidney. PMID:17316817

  14. Contractility Modulates Cell Adhesion Strengthening Through Focal Adhesion Kinase and Assembly of Vinculin-Containing Focal Adhesions

    PubMed Central

    Dumbauld, David W.; Shin, Heungsoo; Gallant, Nathan D.; Michael, Kristin E.; Radhakrishna, Harish; García, Andrés J.

    2010-01-01

    Actin-myosin contractility modulates focal adhesion assembly, stress fiber formation, and cell migration. We analyzed the contributions of contractility to fibroblast adhesion strengthening using a hydrodynamic adhesion assay and micropatterned substrates to control cell shape and adhesive area. Serum addition resulted in adhesion strengthening to levels 30–40% higher than serum-free cultures. Inhibition of myosin light chain kinase or Rho-kinase blocked phosphorylation of myosin light chain to similar extents and eliminated the serum-induced enhancements in strengthening. Blebbistatin-induced inhibition of myosin II reduced serum-induced adhesion strength to similar levels as those obtained by blocking myosin light chain phosphorylation. Reductions in adhesion strengthening by inhibitors of contractility correlated with loss of vinculin and talin from focal adhesions without changes in integrin binding. In vinculin-null cells, inhibition of contractility did not alter adhesive force, whereas controls displayed a 20% reduction in adhesion strength, indicating that the effects of contractility on adhesive force are vinculin-dependent. Furthermore, in cells expressing FAK, inhibitors of contractility reduced serum-induced adhesion strengthening as well as eliminated focal adhesion assembly. In contrast, in the absence of FAK, these inhibitors did not alter adhesion strength or focal adhesion assembly. These results indicate that contractility modulates adhesion strengthening via FAK-dependent, vinculin-containing focal adhesion assembly. PMID:20205236

  15. Adhesion of cells to polystyrene surfaces

    PubMed Central

    1983-01-01

    The surface treatment of polystyrene, which is required to make polystyrene suitable for cell adhesion and spreading, was investigated. Examination of surfaces treated with sulfuric acid or various oxidizing agents using (a) x-ray photoelectron and attenuated total reflection spectroscopy and (b) measurement of surface carboxyl-, hydroxyl-, and sulfur-containing groups by various radiochemical methods showed that sulfuric acid produces an insignificant number of sulfonic acid groups on polystyrene. This technique together with various oxidation techniques that render surfaces suitable for cell culture generated high surface densities of hydroxyl groups. The importance of surface hydroxyl groups for the adhesion of baby hamster kidney cells or leukocytes was demonstrated by the inhibition of adhesion when these groups were blocked: blocking of carboxyl groups did not inhibit adhesion and may raise the adhesion of a surface. These results applied to cell adhesion in the presence and absence of serum. The relative unimportance of fibronectin for the adhesion and spreading of baby hamster kidney cells to hydroxyl-rich surfaces was concluded when cells spread on such surfaces after protein synthesis was inhibited with cycloheximide, fibronectin was removed by trypsinization, and trypsin activity was stopped with leupeptin. PMID:6355120

  16. Antagonists of alcohol inhibition of cell adhesion

    PubMed Central

    Wilkemeyer, Michael F.; Sebastian, Anita B.; Smith, Sherri A.; Charness, Michael E.

    2000-01-01

    Increasing evidence suggests that alcohols act within specific binding pockets of selective neural proteins; however, antagonists at these sites have not been identified. 1-Alcohols from methanol through 1-butanol inhibit with increasing potency the cell–cell adhesion mediated by the immunoglobulin cell adhesion molecule L1. An abrupt cutoff exists after 1-butanol, with 1-pentanol and higher 1-alcohols showing no effect. Here, we demonstrate surprisingly strict structural requirements for alcohol inhibition of cell–cell adhesion in L1-transfected NIH 3T3 fibroblasts and in NG108–15 neuroblastoma × glioma hybrid cells treated with BMP-7, an inducer of L1 and neural cell adhesion molecule. The target site discriminates the tertiary structure of straight-chain and branched-chain alcohols and appears to comprise both a hydrophobic binding site and an adjacent hydrophilic allosteric site. Modifications to the 2- and 3-carbon positions of 1-butanol increased potency, whereas modifications that restrict movement about the 4-carbon abolished activity. The effects of ethanol and 1-butanol on cell–cell adhesion were antagonized by 1-pentanol (IC50 = 715 μM) and 1-octanol (IC50 = 3.6 μM). Antagonism by 1-octanol was complete, reversible, and noncompetitive. 1-Octanol also antagonized ethanol inhibition of BMP-7 morphogenesis in NG108–15 cells. 1-Octanol and related compounds may prove useful in dissecting the role of altered cell adhesion in ethanol-induced injury of the nervous system. PMID:10725368

  17. Mast cell mediators and peritoneal adhesion formation in the rat.

    PubMed

    Langer, J C; Liebman, S M; Monk, P K; Pelletier, G J

    1995-09-01

    We have previously shown that mast cell stabilization attenuates peritoneal adhesion formation in the rat. The present study investigated the mechanism of this protection. Adhesions were created in weanling rats using cecal scraping and application of 95% ethanol. Rats received specific blockers for the mast cell products histamine, serotonin (5HT), leukotriene D4, and platelet activating factor intraperitoneally 30 min before laparotomy and at the time of abdominal closure. Control animals received saline. Adhesions were assessed blindly 1 week later using a standardized scale. Adhesion formation was not affected by histamine blockade using combined mepyramine and ranitidine, 5-HT1 blockade using methysergide, 5-HT3 blockade using ondansetron, leukotriene D4 blockade using MK-571, or platelet activating factor blockade using WEB-2086. However, blockade of the 5-HT2 receptor using ketanserin resulted in significant dose-dependent attenuation of adhesions compared to saline. These data suggest that mast cells mediate peritoneal adhesion formation in the rat through release of serotonin acting on 5HT2 receptors. Further understanding of this process may lead to new strategies for the prevention of postoperative adhesions.

  18. Analytical cell adhesion chromatography reveals impaired persistence of metastatic cell rolling adhesion to P-selectin

    PubMed Central

    Oh, Jaeho; Edwards, Erin E.; McClatchey, P. Mason; Thomas, Susan N.

    2015-01-01

    ABSTRACT Selectins facilitate the recruitment of circulating cells from the bloodstream by mediating rolling adhesion, which initiates the cell–cell signaling that directs extravasation into surrounding tissues. To measure the relative efficiency of cell adhesion in shear flow for in vitro drug screening, we designed and implemented a microfluidic-based analytical cell adhesion chromatography system. The juxtaposition of instantaneous rolling velocities with elution times revealed that human metastatic cancer cells, but not human leukocytes, had a reduced capacity to sustain rolling adhesion with P-selectin. We define a new parameter, termed adhesion persistence, which is conceptually similar to migration persistence in the context of chemotaxis, but instead describes the capacity of cells to resist the influence of shear flow and sustain rolling interactions with an adhesive substrate that might modulate the probability of extravasation. Among cell types assayed, adhesion persistence to P-selectin was specifically reduced in metastatic but not leukocyte-like cells in response to a low dose of heparin. In conclusion, we demonstrate this as an effective methodology to identify selectin adhesion antagonist doses that modulate homing cell adhesion and engraftment in a cell-subtype-selective manner. PMID:26349809

  19. Functional Peptides from Laminin-1 Improve the Cell Adhesion Capacity of Recombinant Mussel Adhesive Protein.

    PubMed

    Wang, Kai; Ji, Lina; Hua, Zichun

    2017-01-01

    Since cell adhesion is important for cell processes such as migration and proliferation, it is a crucial consideration in biomaterial design and development. Based on the fusion of mussel adhesive protein fp151 with laminin-1-originated functional peptides we designed fusion proteins (fLA4, fLG6 and fAG73) and explored their cell adhesion properties. In our study, cell adhesion analysis showed that protein fLG6 and fLA4 had a significantly higher cell adhesion property for A549 than fp151. Moreover, protein fAG73 also displayed a strong adhesion capacity for Hela cells. In conclusion, the incorporation of functional peptides with integrin and heparin/heparan sulphate binding capacity into mussel adhesive protein will promote the application of mussel adhesive protein as cell adhesion biomaterial. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  20. Bistability of cell adhesion in shear flow.

    PubMed

    Efremov, Artem; Cao, Jianshu

    2011-09-07

    Cell adhesion plays a central role in multicellular organisms helping to maintain their integrity and homeostasis. This complex process involves many different types of adhesion proteins, and synergetic behavior of these proteins during cell adhesion is frequently observed in experiments. A well-known example is the cooperation of rolling and stationary adhesion proteins during the leukocytes extravasation. Despite the fact that such cooperation is vital for proper functioning of the immune system, its origin is not fully understood. In this study we constructed a simple analytic model of the interaction between a leukocyte and the blood vessel wall in shear flow. The model predicts existence of cell adhesion bistability, which results from a tug-of-war between two kinetic processes taking place in the cell-wall contact area-bond formation and rupture. Based on the model results, we suggest an interpretation of several cytoadhesion experiments and propose a simple explanation of the existing synergy between rolling and stationary adhesion proteins, which is vital for effective cell adherence to the blood vessel walls in living organisms.

  1. Induction of Cell Polarization and Migration by a Gradient of Nanoscale Variations in Adhesive Ligand Spacing

    PubMed Central

    Arnold, Marco; Jakubick, Vera C.; Lohmüller, Theobald; Heil, Patrick; Blümmel, Jacques; Cavalcanti-Adam, Elisabetta A.; López-García, Mónica; Walther, Paul; Kessler, Horst; Geiger, Benjamin; Spatz, Joachim P.

    2013-01-01

    Cell interactions with adhesive surfaces play a vital role in the regulation of cell proliferation, viability and differentiation, and affect multiple biological processes. Since cell adhesion depends mainly on the nature and density of the adhesive ligand molecules, spatial molecular patterning, which enables the modulation of adhesion receptor clustering, might affect both the structural and signalling activities of the adhesive interaction. We herein show that cells plated on surfaces that present a molecularly defined spacing gradient of an integrin RGD ligand, can sense small but consistent differences in adhesive ligand spacing of about 1 nm across the cell diameter, which is approximately 61 μm when the spacing includes 70 nm. Consequently, these positional cues induce cell polarization, and initiate cell migration and signalling. We propose that differential positional clustering of the integrin transmembrane receptors is used by cells for exploring and interpreting their environment, at high spatial sensitivity. PMID:18558788

  2. Connexin 43 expressed in endothelial cells modulates monocyte‑endothelial adhesion by regulating cell adhesion proteins.

    PubMed

    Yuan, Dongdong; Sun, Guoliang; Zhang, Rui; Luo, Chenfang; Ge, Mian; Luo, Gangjian; Hei, Ziqing

    2015-11-01

    Adhesion between circulating monocytes and vascular endothelial cells is a key initiator of atherosclerosis. In our previous studies, it was demonstrated that the expression of connexin (Cx)43 in monocytes modulates cell adhesion, however, the effects of the expression of Cx43 in endothelial cells remains to be elucidated. Therefore, the present study investigated the role of the expression of Cx43 in endothelial cells in the process of cell adhesion. A total of four different methods with distinct mechanisms were used to change the function and expression of Cx43 channels in human umbilical vein endothelial cells: Cx43 channel inhibitor (oleamide), enhancer (retinoic acid), overexpression of Cx43 by transfection with pcDNA‑Cx43 and knock‑down of the expression of Cx43 by small interfering RNA against Cx43. The results indicated that the upregulation of the expression of Cx43 enhanced monocyte‑endothelial adhesion and this was markedly decreased by downregulation of Cx43. This mechanism was associated with Cx43‑induced expression of vascular cell adhesion molecule‑1 and intercellular cell adhesion molecule‑1. The effects of Cx43 in endothelial cells was independent of Cx37 or Cx40. These experiments suggested that local regulation of endothelial Cx43 expression within the vasculature regulates monocyte‑endothelial adhesion, a critical event in the development of atherosclerosis and other inflammatory pathologies, with baseline adhesion set by the expression of Cx43. This balance may be crucial in controlling leukocyte involvement in inflammatory cascades.

  3. Yielding Elastic Tethers Stabilize Robust Cell Adhesion

    PubMed Central

    Whitfield, Matt J.; Luo, Jonathon P.; Thomas, Wendy E.

    2014-01-01

    Many bacteria and eukaryotic cells express adhesive proteins at the end of tethers that elongate reversibly at constant or near constant force, which we refer to as yielding elasticity. Here we address the function of yielding elastic adhesive tethers with Escherichia coli bacteria as a model for cell adhesion, using a combination of experiments and simulations. The adhesive bond kinetics and tether elasticity was modeled in the simulations with realistic biophysical models that were fit to new and previously published single molecule force spectroscopy data. The simulations were validated by comparison to experiments measuring the adhesive behavior of E. coli in flowing fluid. Analysis of the simulations demonstrated that yielding elasticity is required for the bacteria to remain bound in high and variable flow conditions, because it allows the force to be distributed evenly between multiple bonds. In contrast, strain-hardening and linear elastic tethers concentrate force on the most vulnerable bonds, which leads to failure of the entire adhesive contact. Load distribution is especially important to noncovalent receptor-ligand bonds, because they become exponentially shorter lived at higher force above a critical force, even if they form catch bonds. The advantage of yielding is likely to extend to any blood cells or pathogens adhering in flow, or to any situation where bonds are stretched unequally due to surface roughness, unequal native bond lengths, or conditions that act to unzip the bonds. PMID:25473833

  4. Drosophila neurotactin mediates heterophilic cell adhesion.

    PubMed Central

    Barthalay, Y; Hipeau-Jacquotte, R; de la Escalera, S; Jiménez, F; Piovant, M

    1990-01-01

    Neurotactin is a 135 kd membrane glycoprotein which consists of a core protein, with an apparent molecular weight of 120 kd, and of N-linked oligosaccharides. In vivo, the protein can be phosphorylated in presence of radioactive orthophosphate. Neurotactin expression in the larval CNS and in primary embryonic cell cultures suggests that it behaves as a contact molecule between neurons or epithelial cells. Electron microscopy studies reveal that neurotactin is uniformly expressed along the areas of contacts between cells, without, however, being restricted to a particular type of junction. It putative adhesive properties have been tested by transfecting non adhesive Drosophila S2 cells with neurotactin cDNA. Heat shocked transfected cells do not aggregate, suggesting that neurotactin does not mediate homophilic cell adhesion. However, these transfected cells bind to a subpopulation of embryonic cells which probably possess a related ligand. The location at cellular junctions between specific neurons or epithelial cells, the heterophilic binding to a putative ligand and the ability to be phosphorylated are consistent with the suggestion that neurotactin functions as an adhesion molecule. Images Fig.1 Fig.2 Fig.3 Fig.4 Fig.5 PMID:2120048

  5. Pattern formation in cell membrane adhesion

    NASA Astrophysics Data System (ADS)

    Discher, Dennis; Hategan, A.; Sengupta, K.; Sackmann, E.

    2004-03-01

    Strong adhesion of highly active cells often nucleates focal adhesions or related structures that are, over time, reinforced by cytoskeleton (actin, etc.). Red cells lack such complex adhesion systems, but they are shown here to also exhibit complex spatial patterns within an adhesive contact zone. While strong adhesion and spreading of the red cell to a dense poly-L-lysine surface appears complete in < 1 s by reflective interference microscopy, over longer times of 10-15 min or more distinct patterns in fluorescently labeled membrane components emerge. The fluorescent lipid Fl-PE (fluorescein phosphoethanolamine), in particular, is seen to diffuse and reorganize (eg. worm-like domains of <500 nm) within the contact zone, independent of whether the cell is intact or ruptured. Lipid patterns are accompanied by visible perturbations in band 3 distribution and weaker perturbations in membrane skeleton actin. Although fluorescent poly-L-lysine is shown to be uniform under cells, pressing down on the membrane quenches the lipid patterns and reveals the topographical basis for pattern formation. Regions of strong contact are thus separated by regions where the membrane is more distant from the surface.

  6. Topographic cell instructive patterns to control cell adhesion, polarization and migration

    PubMed Central

    Ventre, Maurizio; Natale, Carlo Fortunato; Rianna, Carmela; Netti, Paolo Antonio

    2014-01-01

    Topographic patterns are known to affect cellular processes such as adhesion, migration and differentiation. However, the optimal way to deliver topographic signals to provide cells with precise instructions has not been defined yet. In this work, we hypothesize that topographic patterns may be able to control the sensing and adhesion machinery of cells when their interval features are tuned on the characteristic lengths of filopodial probing and focal adhesions (FAs). Features separated by distance beyond the length of filopodia cannot be readily perceived; therefore, the formation of new adhesions is discouraged. If, however, topographic features are separated by a distance within the reach of filopodia extension, cells can establish contact between adjacent topographic islands. In the latter case, cell adhesion and polarization rely upon the growth of FAs occurring on a specific length scale that depends on the chemical properties of the surface. Topographic patterns and chemical properties may interfere with the growth of FAs, thus making adhesions unstable. To test this hypothesis, we fabricated different micropatterned surfaces displaying feature dimensions and adhesive properties able to interfere with the filopodial sensing and the adhesion maturation, selectively. Our data demonstrate that it is possible to exert a potent control on cell adhesion, elongation and migration by tuning topographic features’ dimensions and surface chemistry. PMID:25253035

  7. A new quantitative experimental approach to investigate single cell adhesion on multifunctional substrates.

    PubMed

    Canale, Claudio; Petrelli, Alessia; Salerno, Marco; Diaspro, Alberto; Dante, Silvia

    2013-10-15

    Cell adhesion is fundamental for the organization of cells in multicellular organisms since it has a key role in several physiological functions that drive tissue formation and development. A better knowledge of the affections that influence the adhesion capability of cells in several pathologies, such as cancer diseases or multiple sclerosis could enable the development of new therapeutical strategies. Whereas the optimal control of cell adhesion and growth on new technological materials is a primary issue in modern tissue engineering, few techniques are able to provide quantitative and reliable results on cell adhesion. We present a method that enables the investigation of cell adhesion at the single cell level and provides the capability to test the adhesion of a single cell on multifunctional substrates. To reach this goal we applied single cell force spectroscopy (SCFS) on custom designed patterns of molecules prepared on a rigid substrate by using a cantilever based molecule deposition tool, and we tested the adhesion of Chinese Hamster Ovary cells and Human Embrionic Kidney cells on two polyelectrolytes that are widely used as adhesive factors for cells growth: Polyethylenimine and Poly-D-Lysine. Our results confirm the common hypothesis on the mechanism of adhesion promotion by protonated molecules. Optimizations of the experimental settings of SFCS experiment are introduced here. The presented technique offers the unique opportunity to be extended to the study of cell adhesion on an unlimited number molecular species. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Interferon-alpha and dexamethasone inhibit adhesion of T cells to endothelial cells and synovial cells

    PubMed Central

    Eguchi, K.; Kawakami, A.; Nakashima, M.; Ida, H.; Sakito, S.; Matsuoka, N.; Terada, K.; Sakai, M.; Kawabe, Y.; Fukuda, T.; Ishimaru, T.; Kurouji, K.; Fujita, N.; Aoyagi, T.; Maeda, K.; Nagataki, S.

    1992-01-01

    We investigated whether interferon-gamma (IFN-γ), interferon-alpha (IFN-α) and glucocorticoids affected the adhesion of T cells to human umbilical endothelial cells or human synovial cells. About 30% of peripheral blood T cells could bind to unstimulated endothelial cells, but only a few T cells could bind to unstimulated synovial cells. When both endothelial cells and synovial cells were cultured with recombinant IFN-γ (rIFN-γ), the percentage of T cell binding to both types of cells increased in a dose-dependent manner. rIFN-α and dexamethasone blocked the T cell binding to unstimulated endothelial cells. Furthermore, rIFN-α and dexamethasone suppressed T cell binding to both endothelial cells and synovial cells stimulated by IFN-γ, and also inhibited intercellular adhesion molecule-1 (ICAM-1) expression on both endothelial cells and synovial cells stimulated by IFN-γ. These results suggest that IFN-α and glucocorticoids may inhibit T cell binding to endothelial cells or synovial cells by modulating adhesion molecule expression on these cells. PMID:1606729

  9. ADAMTS-10 and -6 differentially regulate cell-cell junctions and focal adhesions.

    PubMed

    Cain, Stuart A; Mularczyk, Ewa J; Singh, Mukti; Massam-Wu, Teresa; Kielty, Cay M

    2016-10-25

    ADAMTS10 and ADAMTS6 are homologous metalloproteinases with ill-defined roles. ADAMTS10 mutations cause Weill-Marchesani syndrome (WMS), implicating it in fibrillin microfibril biology since some fibrillin-1 mutations also cause WMS. However little is known about ADAMTS6 function. ADAMTS10 is resistant to furin cleavage, however we show that ADAMTS6 is effectively processed and active. Using siRNA, over-expression and mutagenesis, it was found ADAMTS6 inhibits and ADAMTS10 is required for focal adhesions, epithelial cell-cell junction formation, and microfibril deposition. Either knockdown of ADAMTS6, or disruption of its furin processing or catalytic sites restores focal adhesions, implicating its enzyme activity acts on targets in the focal adhesion complex. In ADAMTS10-depleted cultures, expression of syndecan-4 rescues focal adhesions and cell-cell junctions. Recombinant C-termini of ADAMTS10 and ADAMTS6, both of which induce focal adhesions, bind heparin and syndecan-4. However, cells overexpressing full-length ADAMTS6 lack heparan sulphate and focal adhesions, whilst depletion of ADAMTS6 induces a prominent glycocalyx. Thus ADAMTS10 and ADAMTS6 oppositely affect heparan sulphate-rich interfaces including focal adhesions. We previously showed that microfibril deposition requires fibronectin-induced focal adhesions, and cell-cell junctions in epithelial cultures. Here we reveal that ADAMTS6 causes a reduction in heparan sulphate-rich interfaces, and its expression is regulated by ADAMTS10.

  10. ADAMTS-10 and -6 differentially regulate cell-cell junctions and focal adhesions

    PubMed Central

    Cain, Stuart A.; Mularczyk, Ewa J.; Singh, Mukti; Massam-Wu, Teresa; Kielty, Cay M.

    2016-01-01

    ADAMTS10 and ADAMTS6 are homologous metalloproteinases with ill-defined roles. ADAMTS10 mutations cause Weill-Marchesani syndrome (WMS), implicating it in fibrillin microfibril biology since some fibrillin-1 mutations also cause WMS. However little is known about ADAMTS6 function. ADAMTS10 is resistant to furin cleavage, however we show that ADAMTS6 is effectively processed and active. Using siRNA, over-expression and mutagenesis, it was found ADAMTS6 inhibits and ADAMTS10 is required for focal adhesions, epithelial cell-cell junction formation, and microfibril deposition. Either knockdown of ADAMTS6, or disruption of its furin processing or catalytic sites restores focal adhesions, implicating its enzyme activity acts on targets in the focal adhesion complex. In ADAMTS10-depleted cultures, expression of syndecan-4 rescues focal adhesions and cell-cell junctions. Recombinant C-termini of ADAMTS10 and ADAMTS6, both of which induce focal adhesions, bind heparin and syndecan-4. However, cells overexpressing full-length ADAMTS6 lack heparan sulphate and focal adhesions, whilst depletion of ADAMTS6 induces a prominent glycocalyx. Thus ADAMTS10 and ADAMTS6 oppositely affect heparan sulphate-rich interfaces including focal adhesions. We previously showed that microfibril deposition requires fibronectin-induced focal adhesions, and cell-cell junctions in epithelial cultures. Here we reveal that ADAMTS6 causes a reduction in heparan sulphate-rich interfaces, and its expression is regulated by ADAMTS10. PMID:27779234

  11. Regulation of Cell–Cell Adhesion by Rac and Rho Small G Proteins in MDCK Cells

    PubMed Central

    Takaishi, Kenji; Sasaki, Takuya; Kotani, Hirokazu; Nishioka, Hideo; Takai, Yoshimi

    1997-01-01

    The Rho small G protein family, consisting of the Rho, Rac, and Cdc42 subfamilies, regulates various cell functions, such as cell shape change, cell motility, and cytokinesis, through reorganization of the actin cytoskeleton. We show here that the Rac and Rho subfamilies furthermore regulate cell–cell adhesion. We prepared MDCK cell lines stably expressing each of dominant active mutants of RhoA (sMDCK-RhoDA), Rac1 (sMDCK-RacDA), and Cdc42 (sMDCK-Cdc42DA) and dominant negative mutants of Rac1 (sMDCK-RacDN) and Cdc42 (sMDCK-Cdc42DN) and analyzed cell adhesion in these cell lines. The actin filaments at the cell–cell adhesion sites markedly increased in sMDCK-RacDA cells, whereas they apparently decreased in sMDCK-RacDN cells, compared with those in wild-type MDCK cells. Both E-cadherin and β-catenin, adherens junctional proteins, at the cell–cell adhesion sites also increased in sMDCK-RacDA cells, whereas both of them decreased in sMDCK-RacDN cells. The detergent solubility assay indicated that the amount of detergent-insoluble E-cadherin increased in sMDCK-RacDA cells, whereas it slightly decreased in sMDCK-RacDN cells, compared with that in wild-type MDCK cells. In sMDCK-RhoDA, -Cdc42DA, and -Cdc42DN cells, neither of these proteins at the cell–cell adhesion sites was apparently affected. ZO-1, a tight junctional protein, was not apparently affected in any of the transformant cell lines. Electron microscopic analysis revealed that sMDCK-RacDA cells tightly made contact with each other throughout the lateral membranes, whereas wild-type MDCK and sMDCK-RacDN cells tightly and linearly made contact at the apical area of the lateral membranes. These results suggest that the Rac subfamily regulates the formation of the cadherin-based cell– cell adhesion. Microinjection of C3 into wild-type MDCK cells inhibited the formation of both the cadherin-based cell–cell adhesion and the tight junction, but microinjection of C3 into sMDCK-RacDA cells showed little

  12. Monoether-tagged Biodegradable Polycarbonate Preventing Platelet Adhesion and Demonstrating Vascular Cell Adhesion: A Promising Material for Resorbable Vascular Grafts and Stents.

    PubMed

    Fukushima, Kazuki; Inoue, Yuto; Haga, Yuta; Ota, Takayuki; Honda, Kota; Sato, Chikako; Tanaka, Masaru

    2017-10-03

    We developed a biodegradable polycarbonate that demonstrates antithrombogenicity and vascular cell adhesion via organocatalytic ring-opening polymerization of a trimethylene carbonate (TMC) analog bearing a methoxy group. The monoether-tagged polycarbonate demonstrates a platelet adhesion property, 93% and 89% lower than poly(ethylene terephthalate) and polyTMC, respectively. In contrast, vascular cell adhesion properties of the polycarbonate are comparable to those controls, indicating a potential for selective cell adhesion properties. This difference in the cell adhesion property is well associated with surface hydration, which affects protein adsorption and denaturation. Fibrinogen is slightly denatured on the monoether-tagged polycarbonate, whereas fibronectin is highly activated to expose the RGD motif for favorable vascular cell adhesion. The surface hydration, mainly induced by the methoxy side chain, also contributes in slowing the enzymatic degradation. Consequently, the polycarbonate exhibits decent blood compatibility, vascular cell adhesion properties, and biodegradability, which is promising for applications in resorbable vascular grafts and stents.

  13. Collective cell streams in epithelial monolayers depend on cell adhesion

    NASA Astrophysics Data System (ADS)

    Czirók, András; Varga, Katalin; Méhes, Előd; Szabó, András

    2013-07-01

    We report spontaneously emerging, randomly oriented, collective streaming behavior within a monolayer culture of a human keratinocyte cell line, and explore the effect of modulating cell adhesions by perturbing the function of calcium-dependent cell adhesion molecules. We demonstrate that decreasing cell adhesion induces narrower and more anisotropic cell streams, reminiscent of decreasing the Taylor scale of turbulent liquids. To explain our empirical findings, we propose a cell-based model that represents the dual nature of cell-cell adhesions. Spring-like connections provide mechanical stability, while a cellular Potts model formalism represents surface-tension driven attachment. By changing the relevance and persistence of mechanical links between cells, we are able to explain the experimentally observed changes in emergent flow patterns.

  14. Adhesion molecules--The lifelines of multiple myeloma cells.

    PubMed

    Katz, Ben-Zion

    2010-06-01

    Multiple myeloma is an incurable hematological malignancy of terminally differentiated immunoglobulin-producing plasma cells. As a common presentation of the disease, the malignant plasma cells accumulate and proliferate in the bone marrow, where they disrupt normal hematopoiesis and bone physiology. Multiple myeloma cells and the bone marrow microenvironment are linked by a composite network of interactions mediated by soluble factors and adhesion molecules. Integrins and syndecan-1/CD138 are the principal multiple myeloma receptor systems of extracellular matrix components, as well as of surface molecules of stromal cells. CD44 and RHAMM are the major hyaluronan receptors of multiple myeloma cells. The SDF-1/CXCR4 axis is a key factor in the homing of multiple myeloma cells to the bone marrow. The levels of expression and activity of these adhesion molecules are controlled by cytoplasmic operating mechanisms, as well as by extracellular factors including enzymes, growth factors and microenvironmental conditions. Several signaling responses are activated by adhesive interactions of multiple myeloma cells, and their outcomes affect the survival, proliferation and migration of these cells, and in many cases generate a drug-resistant phenotype. Hence, the adhesion systems of multiple myeloma cells are attractive potential therapeutic targets. Several approaches are being developed to disrupt the activities of adhesion molecules in multiple myeloma cells, including small antagonist molecules, direct targeting by immunoconjugates, stimulation of immune responses against these molecules, and signal transduction inhibitors. These potential novel therapeutics may be incorporated into current treatment schemes, or directed against minimal residual malignant cells during remission. Copyright © 2010. Published by Elsevier Ltd.

  15. Expression of the melanoma cell adhesion molecule in human mesenchymal stromal cells regulates proliferation, differentiation, and maintenance of hematopoietic stem and progenitor cells

    PubMed Central

    Stopp, Sabine; Bornhäuser, Martin; Ugarte, Fernando; Wobus, Manja; Kuhn, Matthias; Brenner, Sebastian; Thieme, Sebastian

    2013-01-01

    The melanoma cell adhesion molecule defines mesenchymal stromal cells in the human bone marrow that regenerate bone and establish a hematopoietic microenvironment in vivo. The role of the melanoma cell adhesion molecule in primary human mesenchymal stromal cells and the maintenance of hematopoietic stem and progenitor cells during ex vivo culture has not yet been demonstrated. We applied RNA interference or ectopic overexpression of the melanoma cell adhesion molecule in human mesenchymal stromal cells to evaluate the effect of the melanoma cell adhesion molecule on their proliferation and differentiation as well as its influence on co-cultivated hematopoietic stem and progenitor cells. Knockdown and overexpression of the melanoma cell adhesion molecule affected several characteristics of human mesenchymal stromal cells related to osteogenic differentiation, proliferation, and migration. Furthermore, knockdown of the melanoma cell adhesion molecule in human mesenchymal stromal cells stimulated the proliferation of hematopoietic stem and progenitor cells, and strongly reduced the formation of long-term culture-initiating cells. In contrast, melanoma cell adhesion molecule-overexpressing human mesenchymal stromal cells provided a supportive microenvironment for hematopoietic stem and progenitor cells. Expression of the melanoma cell adhesion molecule increased the adhesion of hematopoietic stem and progenitor cells to human mesenchymal stromal cells and their migration beneath the monolayer of human mesenchymal stromal cells. Our results demonstrate that the expression of the melanoma cell adhesion molecule in human mesenchymal stromal cells determines their fate and regulates the maintenance of hematopoietic stem and progenitor cells through direct cell-cell contact. PMID:22801967

  16. Expression of the melanoma cell adhesion molecule in human mesenchymal stromal cells regulates proliferation, differentiation, and maintenance of hematopoietic stem and progenitor cells.

    PubMed

    Stopp, Sabine; Bornhäuser, Martin; Ugarte, Fernando; Wobus, Manja; Kuhn, Matthias; Brenner, Sebastian; Thieme, Sebastian

    2013-04-01

    The melanoma cell adhesion molecule defines mesenchymal stromal cells in the human bone marrow that regenerate bone and establish a hematopoietic microenvironment in vivo. The role of the melanoma cell adhesion molecule in primary human mesenchymal stromal cells and the maintenance of hematopoietic stem and progenitor cells during ex vivo culture has not yet been demonstrated. We applied RNA interference or ectopic overexpression of the melanoma cell adhesion molecule in human mesenchymal stromal cells to evaluate the effect of the melanoma cell adhesion molecule on their proliferation and differentiation as well as its influence on co-cultivated hematopoietic stem and progenitor cells. Knockdown and overexpression of the melanoma cell adhesion molecule affected several characteristics of human mesenchymal stromal cells related to osteogenic differentiation, proliferation, and migration. Furthermore, knockdown of the melanoma cell adhesion molecule in human mesenchymal stromal cells stimulated the proliferation of hematopoietic stem and progenitor cells, and strongly reduced the formation of long-term culture-initiating cells. In contrast, melanoma cell adhesion molecule-overexpressing human mesenchymal stromal cells provided a supportive microenvironment for hematopoietic stem and progenitor cells. Expression of the melanoma cell adhesion molecule increased the adhesion of hematopoietic stem and progenitor cells to human mesenchymal stromal cells and their migration beneath the monolayer of human mesenchymal stromal cells. Our results demonstrate that the expression of the melanoma cell adhesion molecule in human mesenchymal stromal cells determines their fate and regulates the maintenance of hematopoietic stem and progenitor cells through direct cell-cell contact.

  17. Expression, purification, and analysis of three recombinant ECD disintegrins (r-colombistatins) from P-III class snake venom metalloproteinases affecting platelet aggregation and SK-MEL-28 cell adhesion

    PubMed Central

    Suntravat, Montamas; Helmke, Thomas J.; Atphaisit, Chairat; Cuevas, Esteban; Lucena, Sara E.; Uzcátegui, Nestor L.; Sánchez, Elda E.; Rodriguez-Acosta, Alexis

    2016-01-01

    Crotalid venoms are rich sources of components that affect the hemostatic system. Snake venom metalloproteinases are zinc-dependent enzymes responsible for hemorrhage that also interfere with hemostasis. The disintegrin domain is a part of snake venom metalloproteinases, which involves the binding of integrin receptors. Integrins play an essential role in cancer survival and invasion, and they have been major targets for drug development and design. Both native and recombinant disintegrins have been widely investigated for their anti-cancer activities in biological systems as well as in vitro and in vivo systems. Here, three new cDNAs encoding ECD disintegrin-like domains of metalloproteinase precursor sequences obtained from a Venezuelan mapanare (Bothrops colombiensis) venom gland cDNA library have been cloned. Three different N- and C-terminal truncated ECD disintegrin-like domains of metalloproteinases named colombistatins 2, 3, and 4 were amplified by PCR, cloned into a pGEX-4T-1 vector, expressed in Escherichia coli BL21, and tested for inhibition of platelet aggregation and inhibition of adhesion of human skin melanoma (SK-Mel-28) cancer cell lines on collagen I. Purified recombinant colombistatins 2, 3, and 4 were able to inhibit ristocetin- and collagen-induced platelet aggregation. r-Colombistatins 2 showed the most potent inhibiting SK-Mel-28 cancer cells adhesion to collagen. These results suggest that colombistatins may have utility in the development of therapeutic tools in the treatment of melanoma cancers and also thrombotic diseases. PMID:27641750

  18. The structure of cell-matrix adhesions: the new frontier.

    PubMed

    Hanein, Dorit; Horwitz, Alan Rick

    2012-02-01

    Adhesions between the cell and the extracellular matrix (ECM) are mechanosensitive multi-protein assemblies that transmit force across the cell membrane and regulate biochemical signals in response to the chemical and mechanical environment. These combined functions in force transduction, signaling and mechanosensing contribute to cellular phenotypes that span development, homeostasis and disease. These adhesions form, mature and disassemble in response to actin organization and physical forces that originate from endogenous myosin activity or external forces by the extracellular matrix. Despite advances in our understanding of the protein composition, interactions and regulation, our understanding of matrix adhesion structure and organization, how forces affect this organization, and how these changes dictate specific signaling events is limited. Insights across multiple structural levels are acutely needed to elucidate adhesion structure and ultimately the molecular basis of signaling and mechanotransduction. Here we describe the challenges and recent advances and prospects for unraveling the structure of cell-matrix adhesions and their response to force. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. The Role of Cell-Cell Adhesion in Wound Healing

    NASA Astrophysics Data System (ADS)

    Khain, Evgeniy; Sander, Leonard M.; Schneider-Mizell, Casey M.

    2007-07-01

    We present a stochastic model which describes fronts of cells invading a wound. In the model cells can move, proliferate, and experience cell-cell adhesion. We find several qualitatively different regimes of front motion and analyze the transitions between them. Above a critical value of adhesion and for small proliferation large isolated clusters are formed ahead of the front. This is mapped onto the well-known ferromagnetic phase transition in the Ising model. For large adhesion, and larger proliferation the clusters become connected (at some fixed time). For adhesion below the critical value the results are similar to our previous work which neglected adhesion. The results are compared with experiments, and possible directions of future work are proposed.

  20. Multi-scale models for cell adhesion

    NASA Astrophysics Data System (ADS)

    Wu, Yinghao; Chen, Jiawen; Xie, Zhong-Ru

    2014-03-01

    The interactions of membrane receptors during cell adhesion play pivotal roles in tissue morphogenesis during development. Our lab focuses on developing multi-scale models to decompose the mechanical and chemical complexity in cell adhesion. Recent experimental evidences show that clustering is a generic process for cell adhesive receptors. However, the physical basis of such receptor clustering is not understood. We introduced the effect of molecular flexibility to evaluate the dynamics of receptors. By delivering new theory to quantify the changes of binding free energy in different cellular environments, we revealed that restriction of molecular flexibility upon binding of membrane receptors from apposing cell surfaces (trans) causes large entropy loss, which dramatically increases their lateral interactions (cis). This provides a new molecular mechanism to initialize receptor clustering on the cell-cell interface. By using the subcellular simulations, we further found that clustering is a cooperative process requiring both trans and cis interactions. The detailed binding constants during these processes are calculated and compared with experimental data from our collaborator's lab.

  1. Computer simulations of cell sorting due to differential adhesion.

    PubMed

    Zhang, Ying; Thomas, Gilberto L; Swat, Maciej; Shirinifard, Abbas; Glazier, James A

    2011-01-01

    The actions of cell adhesion molecules, in particular, cadherins during embryonic development and morphogenesis more generally, regulate many aspects of cellular interactions, regulation and signaling. Often, a gradient of cadherin expression levels drives collective and relative cell motions generating macroscopic cell sorting. Computer simulations of cell sorting have focused on the interactions of cells with only a few discrete adhesion levels between cells, ignoring biologically observed continuous variations in expression levels and possible nonlinearities in molecular binding. In this paper, we present three models relating the surface density of cadherins to the net intercellular adhesion and interfacial tension for both discrete and continuous levels of cadherin expression. We then use then the Glazier-Graner-Hogeweg (GGH) model to investigate how variations in the distribution of the number of cadherins per cell and in the choice of binding model affect cell sorting. We find that an aggregate with a continuous variation in the level of a single type of cadherin molecule sorts more slowly than one with two levels. The rate of sorting increases strongly with the interfacial tension, which depends both on the maximum difference in number of cadherins per cell and on the binding model. Our approach helps connect signaling at the molecular level to tissue-level morphogenesis.

  2. In silico CDM model sheds light on force transmission in cell from focal adhesions to nucleus.

    PubMed

    Milan, Jean-Louis; Manifacier, Ian; Beussman, Kevin M; Han, Sangyoon J; Sniadecki, Nathan J; About, Imad; Chabrand, Patrick

    2016-09-06

    Cell adhesion is crucial for many types of cell, conditioning differentiation, proliferation, and protein synthesis. As a mechanical process, cell adhesion involves forces exerted by the cytoskeleton and transmitted by focal adhesions to extracellular matrix. These forces constitute signals that infer specific biological responses. Therefore, analyzing mechanotransduction during cell adhesion could lead to a better understanding of the mechanobiology of adherent cells. For instance this may explain how, the shape of adherent stem cells influences their differentiation or how the stiffness of the extracellular matrix affects adhesion strength. To assess the mechanical signals involved in cell adhesion, we computed intracellular forces using the Cytoskeleton Divided Medium model in endothelial cells adherent on micropost arrays of different stiffnesses. For each cell, focal adhesion location and forces measured by micropost deflection were used as an input for the model. The cytoskeleton and the nucleoskeleton were computed as systems of multiple tensile and compressive interactions. At the end of computation, the systems respected mechanical equilibrium while exerting the exact same traction force intensities on focal adhesions as the observed cell. The results indicate that not only the level of adhesion forces, but also the shape of the cell has an influence on intracellular tension and on nucleus strain. The combination of experimental micropost technology with the present CDM model constitutes a tool able to estimate the intracellular forces. Copyright © 2016. Published by Elsevier Ltd.

  3. Cell adhesion on nanotextured slippery superhydrophobic substrates.

    PubMed

    Di Mundo, Rosa; Nardulli, Marina; Milella, Antonella; Favia, Pietro; d'Agostino, Riccardo; Gristina, Roberto

    2011-04-19

    In this work, the response of Saos2 cells to polymeric surfaces with different roughness/density of nanometric dots produced by a tailored plasma-etching process has been studied. Topographical features have been evaluated by atomic force microscopy, while wetting behavior, in terms of water-surface adhesion energy, has been evaluated by measurements of drop sliding angle. Saos2 cytocompatibility has been investigated by scanning electron microscopy, fluorescent microscopy, and optical microscopy. The similarity in outer chemical composition has allowed isolation of the impact of the topographical features on cellular behavior. The results indicate that Saos2 cells respond differently to surfaces with different nanoscale topographical features, clearly showing a certain inhibition in cell adhesion when the nanoscale is particularly small. This effect appears to be attenuated in surfaces with relatively bigger nanofeatures, though these express a more pronounced slippery/dry wetting character. © 2011 American Chemical Society

  4. Phylogeny of a neural cell adhesion molecule.

    PubMed

    Hall, A K; Rutishauser, U

    1985-07-01

    The phylogeny of adhesion among cells derived from neural tissue has been examined using a combination of functional and immunological analyses. The presence of the neural cell adhesion molecule (NCAM) was evaluated with respect to NCAM-specific antigenic determinants attached to a polypeptide chain with appropriate electrophoretic properties. By these criteria, NCAM-like molecules were detected in all embryonic and adult vertebrates tested, and an adult mollusc, but not in an adult insect, crustacean, or nematode. The functional assays measured adhesiveness by simple aggregation of neural membrane vesicles, as well as by NCAM-specific binding between membranes from different species. The presence of the NCAM antigen in vertebrate membranes correlated with binding activity in both the NCAM-specific and general adhesion assays, implying that the adhesiveness of these membranes largely reflects NCAM-mediated binding. The results also indicate that NCAM function has been conserved during the evolution of vertebrates, and supports the possibility that mechanisms of nerve-nerve, nerve-muscle, and nerve-glial interaction, which have been demonstrated previously to involve NCAM, may be similar for many chordates. Whereas NCAM was not detected in adult fly and worm, these species did express NCAM-like antigens transiently during early development. These results are consistent with the hypothesis that NCAM is required during several periods of development, and that the functions of this molecule in nematodes and insects may be distinct from or a subset of those that occur in vertebrates. The expanded role of the molecule represented by its expression during later stages of vertebrate development may thus have been an important contribution to the evolution of chordates.

  5. Cell adhesion in plants is under the control of putative O-fucosyltransferases.

    PubMed

    Verger, Stéphane; Chabout, Salem; Gineau, Emilie; Mouille, Grégory

    2016-07-15

    Cell-to-cell adhesion in plants is mediated by the cell wall and the presence of a pectin-rich middle lamella. However, we know very little about how the plant actually controls and maintains cell adhesion during growth and development and how it deals with the dynamic cell wall remodeling that takes place. Here we investigate the molecular mechanisms that control cell adhesion in plants. We carried out a genetic suppressor screen and a genetic analysis of cell adhesion-defective Arabidopsis thaliana mutants. We identified a genetic suppressor of a cell adhesion defect affecting a putative O-fucosyltransferase. Furthermore, we show that the state of cell adhesion is not directly linked with pectin content in the cell wall but instead is associated with altered pectin-related signaling. Our results suggest that cell adhesion is under the control of a feedback signal from the state of the pectin in the cell wall. Such a mechanism could be necessary for the control and maintenance of cell adhesion during growth and development.

  6. Cell adhesion in plants is under the control of putative O-fucosyltransferases

    PubMed Central

    Verger, Stéphane; Chabout, Salem; Gineau, Emilie

    2016-01-01

    Cell-to-cell adhesion in plants is mediated by the cell wall and the presence of a pectin-rich middle lamella. However, we know very little about how the plant actually controls and maintains cell adhesion during growth and development and how it deals with the dynamic cell wall remodeling that takes place. Here we investigate the molecular mechanisms that control cell adhesion in plants. We carried out a genetic suppressor screen and a genetic analysis of cell adhesion-defective Arabidopsis thaliana mutants. We identified a genetic suppressor of a cell adhesion defect affecting a putative O-fucosyltransferase. Furthermore, we show that the state of cell adhesion is not directly linked with pectin content in the cell wall but instead is associated with altered pectin-related signaling. Our results suggest that cell adhesion is under the control of a feedback signal from the state of the pectin in the cell wall. Such a mechanism could be necessary for the control and maintenance of cell adhesion during growth and development. PMID:27317803

  7. Anisotropy of cell adhesive microenvironment governs cell internal organization and orientation of polarity

    PubMed Central

    Théry, Manuel; Racine, Victor; Piel, Matthieu; Pépin, Anne; Dimitrov, Ariane; Chen, Yong; Sibarita, Jean-Baptiste; Bornens, Michel

    2006-01-01

    Control of the establishment of cell polarity is an essential function in tissue morphogenesis and renewal that depends on spatial cues provided by the extracellular environment. The molecular role of cell–cell or cell–extracellular matrix (ECM) contacts on the establishment of cell polarity has been well characterized. It has been hypothesized that the geometry of the cell adhesive microenvironment was directing cell surface polarization and internal organization. To define how the extracellular environment affects cell polarity, we analyzed the organization of individual cells plated on defined micropatterned substrates imposing cells to spread on various combinations of adhesive and nonadhesive areas. The reproducible normalization effect on overall cell compartmentalization enabled quantification of the spatial organization of the actin network and associated proteins, the spatial distribution of microtubules, and the positioning of nucleus, centrosome, and Golgi apparatus. By using specific micropatterns and statistical analysis of cell compartment positions, we demonstrated that ECM geometry determines the orientation of cell polarity axes. The nucleus–centrosome orientations were reproducibly directed toward cell adhesive edges. The anisotropy of the cell cortex in response to the adhesive conditions did not affect the centrosome positioning at the cell centroid. Based on the quantification of microtubule plus end distribution we propose a working model that accounts for that observation. We conclude that, in addition to molecular composition and mechanical properties, ECM geometry plays a key role in developmental processes. PMID:17179050

  8. Characterizing phenolformaldehyde adhesive cure chemistry within the wood cell wall

    Treesearch

    Daniel J. Yelle; John Ralph

    2016-01-01

    Adhesive bonding of wood using phenol-formaldehyde remains the industrial standard in wood product bond durability. Not only does this adhesive infiltrate the cell wall, it also is believed to form primary bonds with wood cell wall polymers, particularly guaiacyl lignin. However, the mechanism by which phenol-formaldehyde adhesive intergrally interacts and bonds to...

  9. Force nanoscopy of cell mechanics and cell adhesion

    NASA Astrophysics Data System (ADS)

    Dufrêne, Yves F.; Pelling, Andrew E.

    2013-05-01

    Cells are constantly exposed to mechanical stimuli in their environment and have several evolved mechanisms to sense and respond to these cues. It is becoming increasingly recognized that many cell types, from bacteria to mammalian cells, possess a diverse set of proteins to translate mechanical cues into biochemical signalling and to mediate cell surface interactions such as cell adhesion. Moreover, the mechanical properties of cells are involved in regulating cell function as well as serving as indicators of disease states. Importantly, the recent development of biophysical tools and nanoscale methods has facilitated a deeper understanding of the role that physical forces play in modulating cell mechanics and cell adhesion. Here, we discuss how atomic force microscopy (AFM) has recently been used to investigate cell mechanics and cell adhesion at the single-cell and single-molecule levels. This knowledge is critical to our understanding of the molecular mechanisms that govern mechanosensing, mechanotransduction, and mechanoresponse in living cells. While pushing living cells with the AFM tip provides a means to quantify their mechanical properties and examine their response to nanoscale forces, pulling single surface proteins with a functionalized tip allows one to understand their role in sensing and adhesion. The combination of these nanoscale techniques with modern molecular biology approaches, genetic engineering and optical microscopies provides a powerful platform for understanding the sophisticated functions of the cell surface machinery, and its role in the onset and progression of complex diseases.

  10. Expression, purification, and analysis of three recombinant ECD disintegrins (r-colombistatins) from P-III class snake venom metalloproteinases affecting platelet aggregation and SK-MEL-28 cell adhesion.

    PubMed

    Suntravat, Montamas; Helmke, Thomas J; Atphaisit, Chairat; Cuevas, Esteban; Lucena, Sara E; Uzcátegui, Nestor L; Sánchez, Elda E; Rodriguez-Acosta, Alexis

    2016-11-01

    Crotalid venoms are rich sources of components that affect the hemostatic system. Snake venom metalloproteinases are zinc-dependent enzymes responsible for hemorrhage that also interfere with hemostasis. The disintegrin domain is a part of snake venom metalloproteinases, which involves the binding of integrin receptors. Integrins play an essential role in cancer survival and invasion, and they have been major targets for drug development and design. Both native and recombinant disintegrins have been widely investigated for their anti-cancer activities in biological systems as well as in vitro and in vivo systems. Here, three new cDNAs encoding ECD disintegrin-like domains of metalloproteinase precursor sequences obtained from a Venezuelan mapanare (Bothrops colombiensis) venom gland cDNA library have been cloned. Three different N- and C-terminal truncated ECD disintegrin-like domains of metalloproteinases named colombistatins 2, 3, and 4 were amplified by PCR, cloned into a pGEX-4T-1 vector, expressed in Escherichia coli BL21, and tested for inhibition of platelet aggregation and inhibition of adhesion of human skin melanoma (SK-Mel-28) cancer cell lines on collagen I. Purified recombinant colombistatins 2, 3, and 4 were able to inhibit ristocetin- and collagen-induced platelet aggregation. r-Colombistatins 2 showed the most potent inhibiting SK-Mel-28 cancer cells adhesion to collagen. These results suggest that colombistatins may have utility in the development of therapeutic tools in the treatment of melanoma cancers and also thrombotic diseases. Copyright © 2016. Published by Elsevier Ltd.

  11. The extracellular electrical resistivity in cell adhesion.

    PubMed

    Gleixner, Raimund; Fromherz, Peter

    2006-04-01

    The interaction of cells in a tissue depends on the nature of the extracellular matrix. The electrical properties of the narrow extracellular space are unknown. Here we consider cell adhesion mediated by extracellular matrix protein on a solid substrate as a model system. We culture human embryonic kidney (HEK293) cells on silica coated with fibronectin and determine the electrical resistivity in the cell-solid junction rhoJ=rJdJ by combining measurements of the sheet resistance rJ and of the distance dJ between membrane and substrate. The sheet resistance is obtained from phase fluorometry of the voltage-sensitive dye ANNINE-5 by alternating-current stimulation from the substrate. The distance is measured by fluorescence interference contrast microscopy. We change the resistivity of the bath in a range from 66 Omega cm to 750 Omega cm and find that the sheet resistance rJ is proportionally enhanced, but that the distance is invariant around dJ=75 nm. In all cases, the resulting resistivity rhoJ is indistinguishable from the resistivity of the bath. A similar result is obtained for rat neurons cultured on polylysine. On that basis, we propose a "bulk resistivity in cell adhesion" model for cell-solid junctions. The observations suggest that the electrical interaction between cells in a tissue is determined by an extracellular space with the electrical properties of bulk electrolyte.

  12. Focal adhesion kinase maintains, but not increases the adhesion of dental pulp cells.

    PubMed

    Qian, Yuyan; Shao, Meiying; Zou, Wenlin; Wang, Linyan; Cheng, Ran; Hu, Tao

    2017-04-01

    Focal adhesion kinase (FAK) functions as a key enzyme in the integrin-mediated adhesion-signalling pathway. Here, we aimed to investigate the effects of FAK on adhesion of human dental pulp (HDP) cells. We transfected lentiviral vectors to silence or overexpress FAK in HDP cells ex vivo. Early cell adhesion, cell survival and focal contacts (FCs)-related proteins (FAK and paxillin) were examined. By using immunofluorescence, the formation of FCs and cytoskeleton was detected, respectively. We found that both adhesion and survival of HDP cells were suppressed by FAK inhibition. However, FAK overexpression slightly inhibited cell adhesion and exhibited no change in cell survival compared with the control. A thick rim of cytoskeleton accumulated and smaller dot-shaped FCs appeared in FAK knockdown cells. Phosphorylation of paxillin (p-paxillin) was inhibited in FAK knockdown cells, verifying that the adhesion was inhibited. Less cytoskeleton and elongated FCs were observed in FAK-overexpressed cells. However, p-paxillin had no significant difference compared with the control. In conclusion, the data suggest that FAK maintains cell adhesion, survival and cytoskeleton formation, but excessive FAK has no positive effects on these aspects.

  13. Inhibition of Adhesion Molecule Gene Expression and Cell Adhesion by the Metabolic Regulator PGC-1α

    PubMed Central

    Minsky, Neri; Roeder, Robert G.

    2016-01-01

    Cell adhesion plays an important role in determining cell shape and function in a variety of physiological and pathophysiological conditions. While links between metabolism and cell adhesion were previously suggested, the exact context and molecular details of such a cross-talk remain incompletely understood. Here we show that PGC-1α, a pivotal transcriptional co-activator of metabolic gene expression, acts to inhibit expression of cell adhesion genes. Using cell lines, primary cells and mice, we show that both endogenous and exogenous PGC-1α down-regulate expression of a variety of cell adhesion molecules. Furthermore, results obtained using mRNA stability measurements as well as intronic RNA expression are consistent with a transcriptional effect of PGC-1α on cell adhesion gene expression. Interestingly, the L2/L3 motifs of PGC-1α, necessary for nuclear hormone receptor activation, are only partly required for inhibition of several cell adhesion genes by PGC-1α. Finally, PGC-1α is able to modulate adhesion of primary fibroblasts and hepatic stellate cells to extracellular matrix proteins. Our results delineate a cross talk between a central pathway controlling metabolic regulation and cell adhesion, and identify PGC-1α as a molecular link between these two major cellular networks. PMID:27984584

  14. Inhibition of Adhesion Molecule Gene Expression and Cell Adhesion by the Metabolic Regulator PGC-1α.

    PubMed

    Minsky, Neri; Roeder, Robert G

    2016-01-01

    Cell adhesion plays an important role in determining cell shape and function in a variety of physiological and pathophysiological conditions. While links between metabolism and cell adhesion were previously suggested, the exact context and molecular details of such a cross-talk remain incompletely understood. Here we show that PGC-1α, a pivotal transcriptional co-activator of metabolic gene expression, acts to inhibit expression of cell adhesion genes. Using cell lines, primary cells and mice, we show that both endogenous and exogenous PGC-1α down-regulate expression of a variety of cell adhesion molecules. Furthermore, results obtained using mRNA stability measurements as well as intronic RNA expression are consistent with a transcriptional effect of PGC-1α on cell adhesion gene expression. Interestingly, the L2/L3 motifs of PGC-1α, necessary for nuclear hormone receptor activation, are only partly required for inhibition of several cell adhesion genes by PGC-1α. Finally, PGC-1α is able to modulate adhesion of primary fibroblasts and hepatic stellate cells to extracellular matrix proteins. Our results delineate a cross talk between a central pathway controlling metabolic regulation and cell adhesion, and identify PGC-1α as a molecular link between these two major cellular networks.

  15. Osteoblast adhesion to orthopaedic implant alloys: Effects of cell adhesion molecules and diamond-like carbon coating

    SciTech Connect

    Kornu, R.; Kelly, M.A.; Smith, R.L.; Maloney, W.J.

    1996-11-01

    In total joint arthroplasty, long-term outcomes depend in part on the biocompatibility of implant alloys. This study analyzed effects of surface finish and diamond-like carbon coating on osteoblast cell adhesion to polished titanium-aluminum-vanadium and polished or grit-blasted cobalt-chromium-molybdenum alloys. Osteoblast binding was tested in the presence and absence of the cell adhesion proteins fibronectin, laminin, fibrinogen, and vitronectin and was quantified by measurement of DNA content. Although adherence occurred in serum-free medium, maximal osteoblast binding required serum and was similar for titanium and cobalt alloys at 2 and 12 hours. With the grit-blasted cobalt alloy, cell binding was reduced 48% (p < 0.05) by 24 hours. Coating the alloys with diamond-like carbon did not alter osteoblast adhesion, whereas fibronectin pretreatment increased cell binding 2.6-fold (p < 0.05). In contrast, fibrinogen, vitronectin, and laminin did not enhance cell adhesion. These results support the hypothesis that cell adhesion proteins can modify cell binding to orthopaedic alloys. Although osteoblast binding was not affected by the presence of diamond-like carbon, this coating substance may influence other longer term processes, such as bone formation, and deserves further study. 40 refs., 4 figs.

  16. Identification of genes affecting production of the adhesion organelle of Caulobacter crescentus CB2.

    PubMed Central

    Mitchell, D; Smit, J

    1990-01-01

    Transposon (Tn5) mutagenesis was used to identify regions in the genome involved with production, regulation, or attachment to the cell surface of the adhesive holdfast of the freshwater bacterium Caulobacter crescentus CB2. A total of 12,000 independently selected transposon insertion mutants were screened for defects in adhesion to cellulose acetate; 77 mutants were detected and examined by Southern blot hybridization mapping methods and pulsed-field gel electrophoresis. Ten unique sites of Tn5 insertion affecting holdfast function were identified that were clustered in four regions of the genome. Representative mutants of the 10 Tn5 insertion sites were examined by a variety of methods for differences in their phenotype leading to the loss of adhesiveness. Four phenotypes were identified: no holdfast production, production of a smaller or an altered holdfast, production of a holdfast that was unable to remain attached to the cell, and a fourth category in which a possible alteration of the stalk was related to impaired adhesion of the cell. With the possible exception of the last class, no pleiotropic mutants (those with multiple defects in the polar region of the cell) were detected among the adhesion-defective mutants. This was unexpected, since holdfast deficiency is often a characteristic of pleiotropic mutants obtained when selecting for loss of other polar structures. Overall, the evidence suggests that we have identified regions containing structural genes for the holdfast, genes involved with proper attachment or positioning on the caulobacter surface, and possibly regions that regulate the levels of holdfast production. Images PMID:2168382

  17. ICAM-1-independent adhesion of neutrophils to phorbol ester-stimulated human airway epithelial cells.

    PubMed

    Celi, A; Cianchetti, S; Petruzzelli, S; Carnevali, S; Baliva, F; Giuntini, C

    1999-09-01

    Intercellular adhesion molecule-1 (ICAM-1) is the only inducible adhesion receptor for neutrophils identified in bronchial epithelial cells. We stimulated human airway epithelial cells with various agonists to evaluate whether ICAM-1-independent adhesion mechanisms could be elicited. Phorbol 12-myristate 13-acetate (PMA) stimulation of cells of the alveolar cell line A549 caused a rapid, significant increase in neutrophil adhesion from 11 +/- 3 to 49 +/- 7% (SE). A significant increase from 17 +/- 4 to 39 +/- 6% was also observed for neutrophil adhesion to PMA-stimulated human bronchial epithelial cells in primary culture. Although ICAM-1 expression was upregulated by PMA at late time points, it was not affected at 10 min when neutrophil adhesion was already clearly enhanced. Antibodies to ICAM-1 had no effect on neutrophil adhesion. In contrast, antibodies to the leukocyte integrin beta-chain CD18 totally inhibited the adhesion of neutrophils to PMA-stimulated epithelial cells. These results demonstrate that PMA stimulation of human airway epithelial cells causes an increase in neutrophil adhesion that is not dependent on ICAM-1 upregulation.

  18. Tuning cell adhesion by direct nanostructuring silicon into cell repulsive/adhesive patterns.

    PubMed

    Premnath, Priyatha; Tavangar, Amirhossein; Tan, Bo; Venkatakrishnan, Krishnan

    2015-09-10

    Developing platforms that allow tuning cell functionality through incorporating physical, chemical, or mechanical cues onto the material surfaces is one of the key challenges in research in the field of biomaterials. In this respect, various approaches have been proposed and numerous structures have been developed on a variety of materials. Most of these approaches, however, demand a multistep process or post-chemical treatment. Therefore, a simple approach would be desirable to develop bio-functionalized platforms for effectively modulating cell adhesion and consequently programming cell functionality without requiring any chemical or biological surface treatment. This study introduces a versatile yet simple laser approach to structure silicon (Si) chips into cytophobic/cytophilic patterns in order to modulate cell adhesion and proliferation. These patterns are fabricated on platforms through direct laser processing of Si substrates, which renders a desired computer-generated configuration into patterns. We investigate the morphology, chemistry, and wettability of the platform surfaces. Subsequently, we study the functionality of the fabricated platforms on modulating cervical cancer cells (HeLa) behaviour. The results from in vitro studies suggest that the nanostructures efficiently repel HeLa cells and drive them to migrate onto untreated sites. The study of the morphology of the cells reveals that cells evade the cytophobic area by bending and changing direction. Additionally, cell patterning, cell directionality, cell channelling, and cell trapping are achieved by developing different platforms with specific patterns. The flexibility and controllability of this approach to effectively structure Si substrates to cell-repulsive and cell-adhesive patterns offer perceptible outlook for developing bio-functionalized platforms for a variety of biomedical devices. Moreover, this approach could pave the way for developing anti-cancer platforms that selectively repel

  19. Quantification of cell adhesion interactions by AFM: effects of LPS/PMA on the adhesion of C 6 glioma cell to collagen type I

    NASA Astrophysics Data System (ADS)

    Kim, Hyonchol; Arakawa, Hideo; Osada, Toshiya; Ikai, Atsushi

    2002-03-01

    Time-course effects of lipopolysaccharide (LPS) with phorbol-12-myristate-13-acetate (PMA) were quantitatively examined using an atomic force microscope (AFM) cantilever with a type I collagen-coated spherical bead as a probe. LPS/PMA affects the expression level of fibronectin (FN), increasing the adhesion strength for collagen type I about 1.7 times. After 4 days, the adhesion strength for collagen increased 1.6 times. Our method is suitable for quantitative studies of cell adhesion phenomena on the single cell level.

  20. Effect of Rebamipide, a Novel Antiulcer Agent, on Helicobacter pylori Adhesion to Gastric Epithelial Cells

    PubMed Central

    Hayashi, Shunji; Sugiyama, Toshiro; Amano, Ken-Ichi; Isogai, Hiroshi; Isogai, Emiko; Aihara, Miki; Kikuchi, Mikio; Asaka, Masahiro; Yokota, Kenji; Oguma, Keiji; Fujii, Nobuhiro; Hirai, Yoshikazu

    1998-01-01

    Helicobacter pylori is a major etiological agent in gastroduodenal disorders. The adhesion of H. pylori to human gastric epithelial cells is the initial step of H. pylori infection. Inhibition of H. pylori adhesion is thus a therapeutic target in the prevention of H. pylori infection. Experiments were performed to evaluate the effect of rebamipide, a novel antiulcer agent, on H. pylori adhesion to gastric epithelial cells. MKN-28 and MKN-45 cells, derived from human gastric carcinomas, were used as target cells. Ten H. pylori strains isolated from patients with chronic gastritis and gastric ulcer were used in the study. We evaluated the effect of rebamipide on H. pylori adhesion to MKN-28 and MKN-45 cells quantitatively using our previously established enzyme-linked immunosorbent assay. The adhesion of H. pylori to MKN-28 and MKN-45 cells was significantly inhibited by pretreatment of these cells with 100 μg of rebamipide per ml. However, the adhesion was not affected by the pretreatment of H. pylori with rebamipide. On the other hand, the viabilities of H. pylori, MKN-28 cells, and MKN-45 cells were not affected by rebamipide. Our studies suggest that rebamipide inhibits the adhesion of H. pylori to gastric epithelial cells. PMID:9687380

  1. OSTEOBLAST ADHESION OF BREAST CANCER CELLS WITH SCANNING ACOUSTIC MICROSCOPY

    SciTech Connect

    Chiaki Miyasaka; Robyn R. Mercer; Andrea M. Mastro; Ken L. Telschow

    2005-03-01

    Breast cancer frequently metastasizes to the bone. Upon colonizing bone tissue, the cancer cells stimulate osteoclasts (cells that break bone down), resulting in large lesions in the bone. The breast cancer cells also affect osteoblasts (cells that build new bone). Conditioned medium was collected from a bone-metastatic breast cancer cell line, MDA-MB-231, and cultured with an immature osteoblast cell line, MC3T3-E1. Under these conditions the osteoblasts acquired a changed morphology and appeared to adherer in a different way to the substrate and to each other. To characterize cell adhesion, MC3T3-E1 osteoblasts were cultured with or without MDA-MB-231 conditioned medium for two days, and then assayed with a mechanical scanning acoustic reflection microscope (SAM). The SAM indicated that in normal medium the MC3T3-E1 osteoblasts were firmly attached to their plastic substrate. However, MC3T3-E1 cells cultured with MDA-MB-231 conditioned medium displayed both an abnormal shape and poor adhesion at the substrate interface. The cells were fixed and stained to visualize cytoskeletal components using optical microscopic techniques. We were not able to observe these differences until the cells were quite confluent after 7 days of culture. However, using the SAM, we were able to detect these changes within 2 days of culture with MDA-MB-231 conditioned medium

  2. Cell adhesion and integrin expression are modulated by oxidative stress in EA.hy 926 cells.

    PubMed

    Lamari, Foudil; Braut-Boucher, Francoise; Pongnimitprasert, Nushjira; Bernard, Maguy; Foglietti, Marie-Jose; Derappe, Christian; Aubery, Michele

    2007-07-01

    The effects of oxidative stress on integrin-mediated cell adhesion to the extracellular matrix (ECM) and related apoptosis were investigated using the EA.hy926 endothelial cells treated (or not) with two oxidants: the hypoxanthine/xanthine oxidase system (HX/XO) or the tert-butyl hydroperoxide (t-BHP) which both increased cell apoptosis. Cell adhesion onto vitronectin (Vn) and fibronectin (Fn) was increased at low concentrations of HX/XO (up to 5 mU/ml) or t-BHP (up to 125 microM) and prevented ROS-induced apoptosis. Flow cytometry analysis of integrin expression showed that the expression of integrin alphav and alpha5 subunits was, respectively, increased and decreased. Cell adhesion inhibition experiments using function-blocking monoclonal antibodies against integrin subunits indicated that alphavbeta1 and alphavbeta3 integrins were involved in adhesion of cells to Vn, and alphavbeta3 integrin played a major role in oxidant-treated cells. For adhesion to Fn, alpha5beta1 and alphavbeta1 integrins were required for oxidant-treated cells. Taken together, the results suggest that reactive oxygen species (ROS) produced either by HX/XO or t-BHP could affect expression and/or activation of specific integrins in the interaction of EA.hy926 cells with ECM.

  3. The coffee diterpene kahweol inhibits tumor necrosis factor-{alpha}-induced expression of cell adhesion molecules in human endothelial cells

    SciTech Connect

    Kim, Hyung Gyun; Kim, Ji Young; Hwang, Yong Pil; Lee, Kyung Jin; Lee, Kwang Youl; Kim, Dong Hee; Kim, Dong Hyun; Jeong, Hye Gwang . E-mail: hgjeong@chosun.ac.kr

    2006-12-15

    Endothelial cells produce adhesion molecules after being stimulated with various inflammatory cytokines. These adhesion molecules play an important role in the development of atherogenesis. Recent studies have highlighted the chemoprotective and anti-inflammatory effects of kahweol, a coffee-specific diterpene. This study examined the effects of kahweol on the cytokine-induced monocyte/human endothelial cell interaction, which is a crucial early event in atherogenesis. Kahweol inhibited the adhesion of TNF{alpha}-induced monocytes to endothelial cells and suppressed the TNF{alpha}-induced protein and mRNA expression of the cell adhesion molecules, VCAM-1 and ICAM-1. Furthermore, kahweol inhibited the TNF{alpha}-induced JAK2-PI3K/Akt-NF-{kappa}B activation pathway in these cells. Overall, kahweol has anti-inflammatory and anti-atherosclerotic activities, which occurs partly by down-regulating the pathway that affects the expression and interaction of the cell adhesion molecules on endothelial cells.

  4. Cell Adhesion Strength Is Controlled by Intermolecular Spacing of Adhesion Receptors

    PubMed Central

    Selhuber-Unkel, C.; Erdmann, T.; López-García, M.; Kessler, H.; Schwarz, U.S.; Spatz, J.P.

    2010-01-01

    Abstract Spatial patterning of biochemical cues on the micro- and nanometer scale controls numerous cellular processes such as spreading, adhesion, migration, and proliferation. Using force microscopy we show that the lateral spacing of individual integrin receptor-ligand bonds determines the strength of cell adhesion. For spacings ≥90 nm, focal contact formation was inhibited and the detachment forces as well as the stiffness of the cell body were significantly decreased compared to spacings ≤50 nm. Analyzing cell detachment at the subcellular level revealed that rupture forces of focal contacts increase with loading rate as predicted by a theoretical model for adhesion clusters. Furthermore, we show that the weak link between the intra- and extracellular space is at the intracellular side of a focal contact. Our results show that cells can amplify small differences in adhesive cues to large differences in cell adhesion strength. PMID:20159150

  5. Cell substratum adhesion during early development of Dictyostelium discoideum.

    PubMed

    Tarantola, Marco; Bae, Albert; Fuller, Danny; Bodenschatz, Eberhard; Rappel, Wouter-Jan; Loomis, William F

    2014-01-01

    Vegetative and developed amoebae of Dictyostelium discoideum gain traction and move rapidly on a wide range of substrata without forming focal adhesions. We used two independent assays to quantify cell-substrate adhesion in mutants and in wild-type cells as a function of development. Using a microfluidic device that generates a range of hydrodynamic shear stress, we found that substratum adhesion decreases at least 10 fold during the first 6 hr of development of wild type cells. This result was confirmed using a single-cell assay in which cells were attached to the cantilever of an atomic force probe and allowed to adhere to untreated glass surfaces before being retracted. Both of these assays showed that the decrease in substratum adhesion was dependent on the cAMP receptor CAR1 which triggers development. Vegetative cells missing talin as the result of a mutation in talA exhibited slightly reduced adhesive properties compared to vegetative wild-type cells. In sharp contrast to wild-type cells, however, these talA mutant cells did not show further reduction of adhesion during development such that after 5 hr of development they were significantly more adhesive than developed wild type cells. In addition, both assays showed that substrate adhesion was reduced in 0 hr cells when the actin cytoskeleton was disrupted by latrunculin. Consistent with previous observations, substrate adhesion was also reduced in 0 hr cells lacking the membrane proteins SadA or SibA as the result of mutations in sadA or sibA. However, there was no difference in the adhesion properties between wild type AX3 cells and these mutant cells after 6 hr of development, suggesting that neither SibA nor SadA play an essential role in substratum adhesion during aggregation. Our results provide a quantitative framework for further studies of cell substratum adhesion in Dictyostelium.

  6. Tuning cell adhesion by direct nanostructuring silicon into cell repulsive/adhesive patterns

    SciTech Connect

    Premnath, Priyatha; Venkatakrishnan, Krishnan

    2015-09-10

    Developing platforms that allow tuning cell functionality through incorporating physical, chemical, or mechanical cues onto the material surfaces is one of the key challenges in research in the field of biomaterials. In this respect, various approaches have been proposed and numerous structures have been developed on a variety of materials. Most of these approaches, however, demand a multistep process or post-chemical treatment. Therefore, a simple approach would be desirable to develop bio-functionalized platforms for effectively modulating cell adhesion and consequently programming cell functionality without requiring any chemical or biological surface treatment. This study introduces a versatile yet simple laser approach to structure silicon (Si) chips into cytophobic/cytophilic patterns in order to modulate cell adhesion and proliferation. These patterns are fabricated on platforms through direct laser processing of Si substrates, which renders a desired computer-generated configuration into patterns. We investigate the morphology, chemistry, and wettability of the platform surfaces. Subsequently, we study the functionality of the fabricated platforms on modulating cervical cancer cells (HeLa) behaviour. The results from in vitro studies suggest that the nanostructures efficiently repel HeLa cells and drive them to migrate onto untreated sites. The study of the morphology of the cells reveals that cells evade the cytophobic area by bending and changing direction. Additionally, cell patterning, cell directionality, cell channelling, and cell trapping are achieved by developing different platforms with specific patterns. The flexibility and controllability of this approach to effectively structure Si substrates to cell-repulsive and cell-adhesive patterns offer perceptible outlook for developing bio-functionalized platforms for a variety of biomedical devices. Moreover, this approach could pave the way for developing anti-cancer platforms that selectively repel

  7. Role of differential adhesion in cell cluster evolution: from vasculogenesis to cancer metastasis.

    PubMed

    Singh, Jaykrishna; Hussain, Fazle; Decuzzi, Paolo

    2015-01-01

    Cell-cell and cell-matrix adhesions are fundamental to numerous physiological processes, including angiogenesis, tumourigenesis, metastatic spreading and wound healing. We use cellular potts model to computationally predict the organisation of cells within a 3D matrix. The energy potentials regulating cell-cell (JCC) and cell-matrix (JMC) adhesive interactions are systematically varied to represent different, biologically relevant adhesive conditions. Chemotactically induced cell migration is also addressed. Starting from a cluster of cells, variations in relative cell adhesion alone lead to different cellular patterns such as spreading of metastatic tumours and angiogenesis. The combination of low cell-cell adhesion (high JCC) and high heterotypic adhesion (low JMC) favours the fragmentation of the original cluster into multiple, smaller cell clusters (metastasis). Conversely, cellular systems exhibiting high-homotypic affinity (low JCC) preserve their original configuration, avoiding fragmentation (organogenesis). For intermediate values of JCC and JMC (i.e. JCC/JMC ∼ 1), tubular and corrugated structures form. Fully developed vascular trees are assembled only in systems in which contact-inhibited chemotaxis is activated upon cell contact. Also, the rate of secretion, diffusion and sequestration of chemotactic factors, cell deformability and motility do not significantly affect these trends. Further developments of this computational model will predict the efficacy of therapeutic interventions to modulate the diseased microenvironment by directly altering cell cohesion.

  8. Molecular markers of cell adhesion in ameloblastomas. An update

    PubMed Central

    González-González, Rogelio; Molina-Frechero, Nelly; Damian-Matsumura, Pablo

    2014-01-01

    Ameloblastoma is the most common odontogenic tumor of epithelial origin, and though it is of a benign nature, it frequently infiltrates the bone, has a high rate of recurrence and could potentially become malignant. Cellular adhesion potentially plays an important role in the manifestation of these characteristics and in the tumor biology of ameloblastomas. Losses of cell-cell and extracellular matrix adhesion and cohesion are among the first events that occur in the invasion and growth of tumors of epithelial origin. The present review includes a description of the molecules that are involved in cell adhesion as reported for various types of ameloblastomas and discusses the possible roles of these molecules in the biological behaviors of this odontogenic tumor. Knowledge of the complex mechanisms in which these molecules play a role is critical for the research and discovery of future therapeutic targets. Key words:Ameloblastoma, cellular adhesion, molecular markers, cell-cell adhesion, extracellular matrix-cell adhesion. PMID:23986011

  9. Homophilic Adhesion Mechanism of Neurofascin, a Member of the L1 Family of Neural Cell Adhesion Molecules

    SciTech Connect

    Liu, Heli; Focia, Pamela J.; He, Xiaolin

    2012-02-13

    The L1 family neural cell adhesion molecules play key roles in specifying the formation and remodeling of the neural network, but their homophilic interaction that mediates adhesion is not well understood. We report two crystal structures of a dimeric form of the headpiece of neurofascin, an L1 family member. The four N-terminal Ig-like domains of neurofascin form a horseshoe shape, akin to several other immunoglobulin superfamily cell adhesion molecules such as hemolin, axonin, and Dscam. The neurofascin dimer, captured in two crystal forms with independent packing patterns, reveals a pair of horseshoes in trans-synaptic adhesion mode. The adhesion interaction is mediated mostly by the second Ig-like domain, which features an intermolecular {beta}-sheet formed by the joining of two individual GFC {beta}-sheets and a large but loosely packed hydrophobic cluster. Mutagenesis combined with gel filtration assays suggested that the side chain hydrogen bonds at the intermolecular {beta}-sheet are essential for the homophilic interaction and that the residues at the hydrophobic cluster play supplementary roles. Our structures reveal a conserved homophilic adhesion mode for the L1 family and also shed light on how the pathological mutations of L1 affect its structure and function.

  10. Factors Affecting the Processing of Epoxy Film Adhesives

    NASA Technical Reports Server (NTRS)

    Pike, R. A.

    1985-01-01

    The increasing awareness that adhesive performance is controlled not only by the condition of the adherend surface but also the condition or state of the adhesive and the process parameters used during fabrication is expected to result in improved reliability, as well as bond performance. The critical process variables which have been found to control adhesive bond formation and ultimate bond strength in 250F and 350F curing epoxy adhesives are described in terms of fabrication parameters and adhesive characteristics. These include the heat-up rate and cure temperature during processing and the adhesive moisture content and age condition (degree of advancement). The diagnostic methods used to delineate the effects of these process variables on adhesive performance are illustrated. These are dielectric, thermomechanical (TMA) and dynamic mechanical (DMA) analyses. Correlation of test results with measured mechanical tensile lap shear strengths of bonded joints is presented and the results briefly discussed in terms of the additives and hardeners used in the adhesive systems.

  11. Temperature Modulation of Integrin-Mediated Cell Adhesion

    PubMed Central

    Rico, Félix; Chu, Calvin; Abdulreda, Midhat H.; Qin, Yujing; Moy, Vincent T.

    2010-01-01

    In response to external stimuli, cells modulate their adhesive state by regulating the number and intrinsic affinity of receptor/ligand bonds. A number of studies have shown that cell adhesion is dramatically reduced at room or lower temperatures as compared with physiological temperature. However, the underlying mechanism that modulates adhesion is still unclear. Here, we investigated the adhesion of the monocytic cell line THP-1 to a surface coated with intercellular adhesion molecule-1 (ICAM-1) as a function of temperature. THP-1 cells express the integrin lymphocyte function-associated antigen-1 (LFA-1), a receptor for ICAM-1. Direct force measurements of cell adhesion and cell elasticity were carried out by atomic force microscopy. Force measurements revealed an increase of the work of de-adhesion with temperature that was coupled to a gradual decrease in cellular stiffness. Of interest, single-molecule measurements revealed that the rupture force of the LFA-1/ICAM-1 complex decreased with temperature. A detailed analysis of the force curves indicated that temperature-modulated cell adhesion was mainly due to the enhanced ability of cells to deform and to form a greater number of longer membrane tethers at physiological temperatures. Together, these results emphasize the importance of cell mechanics and membrane-cytoskeleton interaction on the modulation of cell adhesion. PMID:20816050

  12. Bond strength of different adhesives to normal and caries-affected dentins.

    PubMed

    Xuan, Wei; Hou, Ben-xiang; Lü, Ya-lin

    2010-02-05

    Currently, several systems of dentin substrate-reacting adhesives are available for use in the restorative treatment against caries. However, the bond effectiveness and property of different adhesive systems to caries-affected dentin are not fully understood. The objective of this study was to evaluate the bond strength of different adhesives to both normal dentin (ND) and caries-affected dentin (CAD) and to analyze the dentin/adhesive interfacial characteristics. Twenty eight extracted human molars with coronal medium carious lesions were randomly assigned to four groups according to adhesives used. ND and CAD were bonded with etch-and-rinse adhesive Adper Single Bond 2 (SB2) or self-etching adhesives Clearfil SE Bond (CSE), Clearfil S(3) Bond (CS3), iBond GI (IB). Rectangular sticks of resin-dentin bonded interfaces 0.9 mm(2) were obtained. The specimens were subjected to microtensile bond strength (microTBS) testing at a crosshead speed of 1 mm/min. Mean microTBS was statistically analyzed with analysis of variance (ANOVA) and Student-Newman-Keuls tests. Interfacial morphologies were analyzed by Scanning Electron Microscopy (SEM). Etch-and-rinse adhesive Adper(TM) Single Bond 2 yielded high bond strength when applied to both normal and caries-affected dentin. The two-step self-etching adhesive Clearfil SE Bond generated the highest bond strength to ND among all adhesives tested but a significantly reduced strength when applied to CAD. For the one-step self-etching adhesives, Clearfil S(3) Bond and iBond GI, the bond strength was relatively low regardless of the dentin type. SEM interfacial analysis revealed that hybrid layers were thicker with poorer resin tag formation and less resin-filled lateral branches in the CAD than in the ND for all the adhesives tested. The etch-and-rinse adhesive performed more effectively to caries-affected dentin than the self-etching adhesives.

  13. Cell Adhesion in Epidermal Development and Barrier Formation

    PubMed Central

    Sumigray, Kaelyn D.; Lechler, Terry

    2015-01-01

    Cell–cell adhesions are necessary for structural integrity and barrier formation of the epidermis. Here, we discuss insights from genetic and cell biological studies into the roles of individual cell–cell junctions and their composite proteins in regulating epidermal development and function. In addition to individual adhesive functions, we will discuss emerging ideas on mechanosensation/transduction of junctions in the epidermis, noncanonical roles for adhesion proteins, and crosstalk/interdependencies between the junctional systems. These studies have revealed that cell adhesion proteins are connected to many aspects of tissue physiology including growth control, differentiation, and inflammation. PMID:25733147

  14. Polymorphonuclear leukocyte adhesion triggers the disorganization of endothelial cell-to-cell adherens junctions

    PubMed Central

    1996-01-01

    Polymorphonuclear leukocytes (PMN) infiltration into tissues is frequently accompanied by increase in vascular permeability. This suggests that PMN adhesion and transmigration could trigger modifications in the architecture of endothelial cell-to-cell junctions. In the present paper, using indirect immunofluorescence, we found that PMN adhesion to tumor necrosis factor-activated endothelial cells (EC) induced the disappearance from endothelial cell-to-cell contacts of adherens junction (AJ) components: vascular endothelial (VE)-cadherin, alpha-catenin, beta-catenin, and plakoglobin. Immunoprecipitation and Western blot analysis of the VE- cadherin/catenin complex showed that the amount of beta-catenin and plakoglobin was markedly reduced from the complex and from total cell extracts. In contrast, VE-cadherin and alpha-catenin were only partially affected. Disorganization of endothelial AJ by PMN was not accompanied by EC retraction or injury and was specific for VE- cadherin/catenin complex, since platelet/endothelial cell adhesion molecule 1 (PECAM-1) distribution at cellular contacts was unchanged. PMN adhesion to EC seems to be a prerequisite for VE-cadherin/catenin complex disorganization. This phenomenon could be fully inhibited by blocking PMN adhesion with an anti-integrin beta 2 mAb, while it could be reproduced by any condition that induced increase of PMN adhesion, such as addition of PMA or an anti-beta 2-activating mAb. The effect on endothelial AJ was specific for PMN since adherent activated lymphocytes did not induce similar changes. High concentrations of protease inhibitors and oxygen metabolite scavengers were unable to prevent AJ disorganization mediated by PMN. PMN adhesion to EC was accompanied by increase in EC permeability in vitro. This effect was dependent on PMN adhesion, was not mediated by proteases and oxygen- reactive metabolites, and could be reproduced by EC treatment with EGTA. Finally, immunohistochemical analysis showed that VE

  15. Cell adhesion molecules: detection with univalent second antibody

    PubMed Central

    1980-01-01

    Identification of cell surface molecules that play a role in cell-cell adhesion (here called cell adhesion molecules) has been achieved by demonstrating the inhibitory effect of univalent antibodies that bind these molecules in an in vitro assay of cell-cell adhesion. A more convenient reagent, intact (divalent) antibody, has been avoided because it might agglutinate the cells rather than blocking cell-cell adhesion. In this report, we show that intact rabbit immunoglobulin directed against certain cell surface molecules of Dictyostelium discoideum blocks cell-cell adhesion when the in vitro assay is performed in the presence of univalent goat anti-rabbit antibody. Under appropriate experimental conditions, the univalent second antibody blocks agglutination induced by the rabbit antibody without significantly interfering with its effect on cell-cell adhesion. This method promises to be useful for screening monoclonal antibodies raised against potential cell adhesion molecules because: (a) it allows for the screening of large numbers of antibody samples without preparation of univalent fragments; and (b) it requires much less antibody because of the greater affinity of divalent antibodies for antigens. PMID:6970200

  16. Ion implantation induced nanotopography on titanium and bone cell adhesion

    NASA Astrophysics Data System (ADS)

    Braceras, Iñigo; Vera, Carolina; Ayerdi-Izquierdo, Ana; Muñoz, Roberto; Lorenzo, Jaione; Alvarez, Noelia; de Maeztu, Miguel Ángel

    2014-08-01

    Permanent endo-osseous implants require a fast, reliable and consistent osseointegration, i.e. intimate bonding between bone and implant, so biomechanical loads can be safely transferred. Among the parameters that affect this process, it is widely admitted that implant surface topography, surface energy and composition play an important role. Most surface treatments to improve osseointegration focus on micro-scale features, as few can effectively control the effects of the treatment at nanoscale. On the other hand, ion implantation allows controlling such nanofeatures. This study has investigated the nanotopography of titanium, as induced by different ion implantation surface treatments, its similarity with human bone tissue structure and its effect on human bone cell adhesion, as a first step in the process of osseointegration. The effect of ion implantation treatment parameters such as energy (40-80 keV), fluence (1-2 e17 ion/cm2) and ion species (Kr, Ar, Ne and Xe) on the nanotopography of medical grade titanium has been measured and assessed by AFM and contact angle. Then, in vitro tests have been performed to assess the effect of these nanotopographies on osteoblast adhesion. The results have shown that the nanostructure of bone and the studied ion implanted surfaces, without surface chemistry modification, are in the same range and that such modifications, in certain conditions, do have a statistically significant effect on bone tissue forming cell adhesion.

  17. Ultraviolet B Inhibits Skin Wound Healing by Affecting Focal Adhesion Dynamics.

    PubMed

    Liu, Han; Yue, Jiping; Lei, Qiang; Gou, Xuewen; Chen, Shao-Yu; He, Yu-Ying; Wu, Xiaoyang

    2015-01-01

    As the most important interface between human body and external environment, skin acts as an essential barrier preventing various environmental damages, among which DNA-damaging UV radiation from the sun remains the major environmental risk factor causing various skin diseases. It has been well documented that wavelengths in the ultraviolet B (UVB) radiation range (290-320 nm) of the solar spectrum can be absorbed by skin and lead to cutaneous injury and various other deleterious effects. During process such as wound healing, the orchestrated movement of cells in a particular direction is essential and highly regulated, integrating signals controlling adhesion, polarity and the cytoskeleton. Cell adhesion and migration are modulated through both of actin and microtubule cytoskeletons. However, little was known about how UVB affects skin wound healing and migration of epidermal keratinocytes. Here, we demonstrate that UVB can delay the wound healing progress in vivo with a murine model of full-thickness skin wound. In addition, UVB significantly inhibited keratinocyte motility by altering focal adhesion turnover and cytoskeletal dynamics. Our results provide new insights into the etiology of UVB exposure-induced skin damages. © 2015 The American Society of Photobiology.

  18. Effect of channel geometry on cell adhesion in microfluidic devices.

    PubMed

    Green, James V; Kniazeva, Tatiana; Abedi, Mehdi; Sokhey, Darshan S; Taslim, Mohammad E; Murthy, Shashi K

    2009-03-07

    Microfluidic channels coated with ligands are a versatile platform for the separation or enrichment of cells from small sample volumes. This adhesion-based mode of separation is mediated by ligand-receptor bonds between the cells and channel surface and also by fluid shear stress. This paper demonstrates how aspects of microchannel geometry can play an additional role in controlling cell adhesion. With a combination of computational fluid dynamics modeling and cell adhesion experiments, channels with sharp turns are shown to have regions with near-zero velocity at the turn regions where large numbers of cells adhere or become collected. The lack of uniform adhesion in the turn regions compared to other regions of these channels, together with the large variability in observed cell adhesion indicates that channels with sharp turns are not optimal for cell-capture applications where predictable cell adhesion is desired. Channels with curved turns, on the other hand are shown to provide more uniform and predictable cell adhesion provided the gap between parallel arms of the channels is sufficiently wide. The magnitude of cell adhesion in these curved channels is comparable to that in straight channels with no turns.

  19. Silencing of VAMP3 inhibits cell migration and integrin-mediated adhesion

    SciTech Connect

    Luftman, Kevin; Hasan, Nazarul; Day, Paul; Hardee, Deborah; Hu Chuan

    2009-02-27

    Integrins are transmembrane receptors for cell adhesion to the extracellular matrix. In cell migration, integrins are endocytosed from the plasma membrane or the cell surface, transported in vesicles and exocytosed actively at the cell front. In the present study, we examined the roles of VAMP3, a SNARE protein that mediates exocytosis, in cell migration and integrin trafficking. Small interfering RNA (siRNA)-induced silencing of VAMP3 inhibited chemotactic cell migration by more than 60% without affecting cell proliferation. VAMP3 silencing reduced the levels of {beta}1 integrin at the cell surface but had no effect on total cellular {beta}1 integrin, indicating that VAMP3 is required for trafficking of {beta}1 integrin to the plasma membrane. Furthermore, VAMP3 silencing diminished cell adhesion to laminin but not to fibronectin or collagen. Taken together, these data suggest that VAMP3-dependent integrin trafficking is crucial in cell migration and cell adhesion to laminin.

  20. Surface free energy predominates in cell adhesion to hydroxyapatite through wettability.

    PubMed

    Nakamura, Miho; Hori, Naoko; Ando, Hiroshi; Namba, Saki; Toyama, Takeshi; Nishimiya, Nobuyuki; Yamashita, Kimihiro

    2016-05-01

    The initial adhesion of cells to biomaterials is critical in the regulation of subsequent cell behaviors. The purpose of this study was to investigate a mechanism through which the surface wettability of biomaterials can be improved and determine the effects of biomaterial surface characteristics on cellular behaviors. We investigated the surface characteristics of various types of hydroxyapatite after sintering in different atmospheres and examined the effects of various surface characteristics on cell adhesion to study cell-biomaterial interactions. Sintering atmosphere affects the polarization capacity of hydroxyapatite by changing hydroxide ion content and grain size. Compared with hydroxyapatite sintered in air, hydroxyapatite sintered in saturated water vapor had a higher polarization capacity that increased surface free energy and improved wettability, which in turn accelerated cell adhesion. We determined the optimal conditions of hydroxyapatite polarization for the improvement of surface wettability and acceleration of cell adhesion.

  1. Redundant control of migration and adhesion by ERM proteins in vascular smooth muscle cells

    SciTech Connect

    Baeyens, Nicolas; Latrache, Iman; Yerna, Xavier; Noppe, Gauthier; Horman, Sandrine; Morel, Nicole

    2013-11-22

    Highlights: •The three ERM proteins are expressed in vascular smooth muscle cell. •ERM depletion inhibited PDGF-evoked migration redundantly. •ERM depletion increased cell adhesion redundantly. •ERM depletion did not affect PDGF-evoked Ca signal, Rac1 activation, proliferation. •ERM proteins control PDGF-induced migration by regulating adhesion. -- Abstract: Ezrin, radixin, and moesin possess a very similar structure with a C-terminal actin-binding domain and a N-terminal FERM interacting domain. They are known to be involved in cytoskeleton organization in several cell types but their function in vascular smooth muscle cells (VSMC) is still unknown. The aim of this study was to investigate the role of ERM proteins in cell migration induced by PDGF, a growth factor involved in pathophysiological processes like angiogenesis or atherosclerosis. We used primary cultured VSMC obtained from rat aorta, which express the three ERM proteins. Simultaneous depletion of the three ERM proteins with specific siRNAs abolished the effects of PDGF on cell architecture and migration and markedly increased cell adhesion and focal adhesion size, while these parameters were only slightly affected by depletion of ezrin, radixin or moesin alone. Rac1 activation, cell proliferation, and Ca{sup 2+} signal in response to PDGF were unaffected by ERM depletion. These results indicate that ERM proteins exert a redundant control on PDGF-induced VSMC migration by regulating focal adhesion turn-over and cell adhesion to substrate.

  2. Exendin-4 Induces Cell Adhesion and Differentiation and Counteracts the Invasive Potential of Human Neuroblastoma Cells

    PubMed Central

    Benvenuti, Susanna; Squecco, Roberta; Cellai, Ilaria; Fibbi, Benedetta; Marone, Ilaria Maddalena; Giuliani, Corinna; Modi, Giulia; Francini, Fabio; Vannelli, Gabriella Barbara; Peri, Alessandro

    2013-01-01

    Exendin-4 is a molecule currently used, in its synthetic form exenatide, for the treatment of type 2 diabetes mellitus. Exendin-4 binds and activates the Glucagon-Like Peptide-1 Receptor (GLP-1R), thus inducing insulin release. More recently, additional biological properties have been associated to molecules that belong to the GLP-1 family. For instance, Peptide YY and Vasoactive Intestinal Peptide have been found to affect cell adhesion and migration and our previous data have shown a considerable actin cytoskeleton rearrangement after exendin-4 treatment. However, no data are currently available on the effects of exendin-4 on tumor cell motility. The aim of this study was to investigate the effects of this molecule on cell adhesion, differentiation and migration in two neuroblastoma cell lines, SH-SY5Y and SK-N-AS. We first demonstrated, by Extra Cellular Matrix cell adhesion arrays, that exendin-4 increased cell adhesion, in particular on a vitronectin substrate. Subsequently, we found that this molecule induced a more differentiated phenotype, as assessed by i) the evaluation of neurite-like protrusions in 3D cell cultures, ii) the analysis of the expression of neuronal markers and iii) electrophysiological studies. Furthermore, we demonstrated that exendin-4 reduced cell migration and counteracted anchorage-independent growth in neuroblastoma cells. Overall, these data indicate for the first time that exendin-4 may have anti-tumoral properties. PMID:23990978

  3. Nitric Oxide Inhibits Hetero-adhesion of Cancer Cells to Endothelial Cells: Restraining Circulating Tumor Cells from Initiating Metastatic Cascade

    NASA Astrophysics Data System (ADS)

    Lu, Yusheng; Yu, Ting; Liang, Haiyan; Wang, Jichuang; Xie, Jingjing; Shao, Jingwei; Gao, Yu; Yu, Suhong; Chen, Shuming; Wang, Lie; Jia, Lee

    2014-03-01

    Adhesion of circulating tumor cells (CTCs) to vascular endothelial bed becomes a crucial starting point in metastatic cascade. We hypothesized that nitric oxide (NO) may prevent cancer metastasis from happening by its direct vasodilation and inhibition of cell adhesion molecules (CAMs). Here we show that S-nitrosocaptopril (CAP-NO, a typical NO donor) produced direct vasorelaxation that can be antagonized by typical NO scavenger hemoglobin and guanylate cyclase inhibitor. Cytokines significantly stimulated production of typical CAMs by the highly-purified human umbilical vein endothelial cells (HUVECs). CAP-NO inhibited expression of the stimulated CAMs (particularly VCAM-1) and the resultant hetero-adhesion of human colorectal cancer cells HT-29 to the HUVECs in a concentration-dependent manner. The same concentration of CAP-NO, however, did not significantly affect cell viability, cell cycle and mitochondrial membrane potential of HT-29, thus excluding the possibility that inhibition of the hetero-adhesion was caused by cytotoxicity by CAP-NO on HT-29. Hemoglobin reversed the inhibition of CAP-NO on both the hetero-adhesion between HT-29 and HUVECs and VCAM-1 expression. These data demonstrate that CAP-NO, by directly releasing NO, produces vasorelaxation and interferes with hetero-adhesion of cancer cells to vascular endothelium via down-regulating expression of CAMs. The study highlights the importance of NO in cancer metastatic prevention.

  4. Adhesion of Actinobacillus actinomycetemcomitans to a human oral cell line.

    PubMed Central

    Mintz, K P; Fives-Taylor, P M

    1994-01-01

    Two quantitative, rapid assays were developed to study the adhesion of Actinobacillus actinomycetemcomitans, an oral bacterium associated with periodontal disease, to human epithelial cells. The human oral carcinoma cell line KB was grown in microtiter plates, and adherent bacteria were detected by an enzyme-linked immunosorbent assay with purified anti-A. actinomycetemcomitans serum and horseradish peroxidase-conjugated secondary antibody or [3H]thymidine-labeled bacteria. Adhesion was found to be time dependent and increased linearly with increasing numbers of bacteria added. Variation in the level of adhesion was noted among strains of A. actinomycetemcomitans. Adhesion was not significantly altered by changes in pH (from pH 5 to 9) but was sensitive to sodium chloride concentrations greater than 0.15 M. Pooled human saliva was inhibitory for adhesion when bacteria were pretreated with saliva before being added to the cells. Pretreatment of the KB cells with saliva did not inhibit adhesion. Protease treatment of A. actinomycetemcomitans reduced adhesion of the bacteria to KB cells. The data are consistent with the hypothesis that a protein(s) is required for bacterial adhesion and that host components may play a role in modulating adhesion to epithelial cells. Images PMID:8063383

  5. Cell Adhesion on Amyloid Fibrils Lacking Integrin Recognition Motif*

    PubMed Central

    Jacob, Reeba S.; George, Edna; Singh, Pradeep K.; Salot, Shimul; Anoop, Arunagiri; Jha, Narendra Nath; Sen, Shamik; Maji, Samir K.

    2016-01-01

    Amyloids are highly ordered, cross-β-sheet-rich protein/peptide aggregates associated with both human diseases and native functions. Given the well established ability of amyloids in interacting with cell membranes, we hypothesize that amyloids can serve as universal cell-adhesive substrates. Here, we show that, similar to the extracellular matrix protein collagen, amyloids of various proteins/peptides support attachment and spreading of cells via robust stimulation of integrin expression and formation of integrin-based focal adhesions. Additionally, amyloid fibrils are also capable of immobilizing non-adherent red blood cells through charge-based interactions. Together, our results indicate that both active and passive mechanisms contribute to adhesion on amyloid fibrils. The present data may delineate the functional aspect of cell adhesion on amyloids by various organisms and its involvement in human diseases. Our results also raise the exciting possibility that cell adhesivity might be a generic property of amyloids. PMID:26742841

  6. Patterned Poly(dopamine) Films for Enhanced Cell Adhesion.

    PubMed

    Chen, Xi; Cortez-Jugo, Christina; Choi, Gwan H; Björnmalm, Mattias; Dai, Yunlu; Yoo, Pil J; Caruso, Frank

    2017-01-18

    Engineered materials that promote cell adhesion and cell growth are important in tissue engineering and regenerative medicine. In this work, we produced poly(dopamine) (PDA) films with engineered patterns for improved cell adhesion. The patterned films were synthesized via the polymerization of dopamine at the air-water interface of a floating bed of spherical particles. Subsequent dissolution of the particles yielded free-standing PDA films with tunable geometrical patterns. Our results show that these patterned PDA films significantly enhance the adhesion of both cancer cells and stem cells, thus showing promise as substrates for cell attachment for various biomedical applications.

  7. Patterned hybrid nanohole array surfaces for cell adhesion and migration.

    PubMed

    Westcott, Nathan P; Lou, Yi; Muth, John F; Yousaf, Muhammad N

    2009-10-06

    We report the fabrication of hybrid nanohole array surfaces to study the role of the surface nanoevironment on cell adhesion and cell migration. We use polystyrene beads and reactive ion etching to control the size and the spacing between nanoholes on a tailored self-assembled monolayer inert gold surface. The arrays were characterized by scanning electron microscopy and brightfield microscopy. For cell adhesion studies, cells were seeded to these substrates to study the effect of ligand spacing on cell spreading, stress fiber formation, and focal adhesion structure and size. Finally, comparative cell migration rates were examined on the various nanohole array surfaces using time-lapse microscopy.

  8. Short Peptides Enhance Single Cell Adhesion and Viability on Microarrays

    PubMed Central

    Veiseh, Mandana; Veiseh, Omid; Martin, Michael C.; Asphahani, Fareid; Zhang, Miqin

    2011-01-01

    Single cell patterning holds important implications for biology, biochemistry, biotechnology, medicine, and bioinformatics. The challenge for single cell patterning is to produce small islands hosting only single cells and retaining their viability for a prolonged period of time. This study demonstrated a surface engineering approach that uses a covalently-bound short peptide as a mediator to pattern cells with improved single cell adhesion and prolonged cellular viability on gold patterned SiO2 substrates. The underlying hypothesis is that cell adhesion is regulated by the type, availability and stability of effective cell adhesion peptides, and thus covalently bound short peptides would promote cell spreading and thus, single cell adhesion and viability. The effectiveness of this approach and the underlying mechanism for the increased probability of single cell adhesion and prolonged cell viability by short peptides were studied by comparing cellular behavior of human umbilical cord vein endothelial cells on three model surfaces whose gold electrodes were immobilized with fibronectin, physically adsorbed Arg-Glu-Asp-Val-Tyr, and covalently-bound Lys-Arg-Glu-Asp-Val-Tyr, respectively. The surface chemistry and binding properties were characterized by reflectance Fourier transform infrared spectroscopy. Both short peptides were superior to fibronectin in producing adhesion of only single cells, while the covalently bound peptide also reduced apoptosis and necrosis of adhered cells. Controlling cell spreading by peptide binding domains to regulate apoptosis and viability represents a fundamental mechanism in cell-materials interaction and provides an effective strategy in engineering arrays of single cells. PMID:17371055

  9. Myoferlin depletion elevates focal adhesion kinase and paxillin phosphorylation and enhances cell-matrix adhesion in breast cancer cells.

    PubMed

    Blackstone, B N; Li, R; Ackerman, W E; Ghadiali, S N; Powell, H M; Kniss, D A

    2015-04-15

    Breast cancer is the second leading cause of malignant death among women. A crucial feature of metastatic cancers is their propensity to lose adhesion to the underlying basement membrane as they transition to a motile phenotype and invade surrounding tissue. Attachment to the extracellular matrix is mediated by a complex of adhesion proteins, including integrins, signaling molecules, actin and actin-binding proteins, and scaffolding proteins. Focal adhesion kinase (FAK) is pivotal for the organization of focal contacts and maturation into focal adhesions, and disruption of this process is a hallmark of early cancer invasive potential. Our recent work has revealed that myoferlin (MYOF) mediates breast tumor cell motility and invasive phenotype. In this study we demonstrate that noninvasive breast cancer cell lines exhibit increased cell-substrate adhesion and that silencing of MYOF using RNAi in the highly invasive human breast cancer cell line MDA-MB-231 also enhances cell-substrate adhesion. In addition, we detected elevated tyrosine phosphorylation of FAK (FAK(Y397)) and paxillin (PAX(Y118)), markers of focal adhesion protein activation. Morphometric analysis of PAX expression revealed that RNAi-mediated depletion of MYOF resulted in larger, more elongated focal adhesions, in contrast to cells transduced with a control virus (MDA-231(LVC) cells), which exhibited smaller focal contacts. Finally, MYOF silencing in MDA-MB-231 cells exhibited a more elaborate ventral cytoskeletal structure near focal adhesions, typified by pronounced actin stress fibers. These data support the hypothesis that MYOF regulates cell adhesions and cell-substrate adhesion strength and may account for the high degree of motility in invasive breast cancer cells.

  10. [Molecular mechanisms underlying cell adhesion--molecules mediating lymphocyte migration].

    PubMed

    Miyasaka, M

    2000-01-01

    Adhesion molecules play crucial roles in a variety of in vivo responses such as development of various tissues in embryos and also in the body defence mechanism in the postnatal period. Defects in adhesion molecules thus result in various pathological disorders. Recent investigation has identified a large number of novel adhesion molecules, particularly those involved in the extravasation of leukocytes including lymphocytes. However, there still appears to be a substantial number of unidentified adhesion molecules. In addition, signal transduction as well as regulatory mechanisms of adhesion molecules remain not fully explored. I will herein describe general characteristics of adhesion molecules and also discuss issues that need to be urgently resolved in the field of cell adhesion.

  11. N-Glycosylation at the SynCAM (Synaptic Cell Adhesion Molecule) Immunoglobulin Interface Modulates Synaptic Adhesion

    SciTech Connect

    A Fogel; Y Li; Q Wang; T Lam; Y Modis; T Biederer

    2011-12-31

    Select adhesion molecules connect pre- and postsynaptic membranes and organize developing synapses. The regulation of these trans-synaptic interactions is an important neurobiological question. We have previously shown that the synaptic cell adhesion molecules (SynCAMs) 1 and 2 engage in homo- and heterophilic interactions and bridge the synaptic cleft to induce presynaptic terminals. Here, we demonstrate that site-specific N-glycosylation impacts the structure and function of adhesive SynCAM interactions. Through crystallographic analysis of SynCAM 2, we identified within the adhesive interface of its Ig1 domain an N-glycan on residue Asn(60). Structural modeling of the corresponding SynCAM 1 Ig1 domain indicates that its glycosylation sites Asn(70)/Asn(104) flank the binding interface of this domain. Mass spectrometric and mutational studies confirm and characterize the modification of these three sites. These site-specific N-glycans affect SynCAM adhesion yet act in a differential manner. Although glycosylation of SynCAM 2 at Asn(60) reduces adhesion, N-glycans at Asn(70)/Asn(104) of SynCAM 1 increase its interactions. The modification of SynCAM 1 with sialic acids contributes to the glycan-dependent strengthening of its binding. Functionally, N-glycosylation promotes the trans-synaptic interactions of SynCAM 1 and is required for synapse induction. These results demonstrate that N-glycosylation of SynCAM proteins differentially affects their binding interface and implicate post-translational modification as a mechanism to regulate trans-synaptic adhesion.

  12. Simulated microgravity does not alter epithelial cell adhesion to matrix and other molecules

    NASA Technical Reports Server (NTRS)

    Jessup, J. M.; Brown, K.; Ishii, S.; Ford, R.; Goodwin, T. J.; Spaulding, G.

    1994-01-01

    Microgravity has advantages for the cultivation of tissues with high fidelity; however, tissue formation requires cellular recognition and adhesion. We tested the hypothesis that simulated microgravity does not affect cell adhesion. Human colorectal carcinoma cells were cultured in the NASA Rotating Wall Vessel (RWV) under low shear stress with randomization of the gravity vector that simulates microgravity. After 6 - 7 days, cells were assayed for binding to various substrates and compared to cells grown in standard tissue culture flasks and static suspension cultures. The RWV cultures bound as well to basement membrane proteins and to Carcinoembryonic Antigen (CEA), an intercellular adhesion molecule, as control cultures did. Thus, microgravity does not alter epithelial cell adhesion and may be useful for tissue engineering.

  13. Simulated microgravity does not alter epithelial cell adhesion to matrix and other molecules

    NASA Technical Reports Server (NTRS)

    Jessup, J. M.; Brown, K.; Ishii, S.; Ford, R.; Goodwin, T. J.; Spaulding, G.

    1994-01-01

    Microgravity has advantages for the cultivation of tissues with high fidelity; however, tissue formation requires cellular recognition and adhesion. We tested the hypothesis that simulated microgravity does not affect cell adhesion. Human colorectal carcinoma cells were cultured in the NASA Rotating Wall Vessel (RWV) under low shear stress with randomization of the gravity vector that simulates microgravity. After 6 - 7 days, cells were assayed for binding to various substrates and compared to cells grown in standard tissue culture flasks and static suspension cultures. The RWV cultures bound as well to basement membrane proteins and to Carcinoembryonic Antigen (CEA), an intercellular adhesion molecule, as control cultures did. Thus, microgravity does not alter epithelial cell adhesion and may be useful for tissue engineering.

  14. Simulated microgravity does not alter epithelial cell adhesion to matrix and other molecules

    NASA Astrophysics Data System (ADS)

    Jessup, J. M.; Brown, K.; Ishii, S.; Ford, R.; Goodwin, T. J.; Spaulding, G.

    1994-08-01

    Microgravity has advantages for the cultivation of tissues with high fidelity; however, tissue formation requires cellular recognition and adhesion. We tested the hypothesis that simulated microgravity does not affect cell adhesion. Human colorectal carcinoma cells were cultured in the NASA Rotating Wall Vessel (RWV) under low shear stress with randomization of the gravity vector that simulates microgravity. After 6 - 7 days, cells were assayed for binding to various substrates and compared to cells grown in standard tissue culture flasks and static suspension cultures. The RWV cultures bound as well to basement membrane proteins and to CEA, an intercellular adhesion molecule, as control cultures did. Thus, microgravity does not alter epithelial cell adhesion and may be useful for tissue engineering.

  15. Study of the adhesion of Bifidobacterium bifidum MIMBb75 to human intestinal cell lines.

    PubMed

    Guglielmetti, Simone; Tamagnini, Isabella; Minuzzo, Mario; Arioli, Stefania; Parini, Carlo; Comelli, Elena; Mora, Diego

    2009-08-01

    The aim of this study was to investigate the adhesive phenotype of the human intestinal isolate Bifidobacterium bifidum MIMBb75 to human colon carcinoma cell lines. We have previously shown that the adhesion of this strain to Caco-2 cells is mediated by an abundant surface lipoprotein named BopA. In this study, we found that this strain adheres to Caco-2 and HT-29 cells, and that its adhesion strongly depends on the environmental conditions, including the presence of sugars and bile salts and the pH. Considerably more adhesion to a Caco-2 monolayer occurred in the presence of fucose and mannose and less when MIMBb75 grew in Oxgall bile salts compared to standard environmental conditions. In particular, growth in Oxgall bile salts reduced the adhesion ability of MIMBb75 and modified the SDS-PAGE profile of the cell wall associated proteins of the strain. The pH markedly affected both adhesion to Caco-2 and bacterial autoaggregation. Finally, experiments with sodium metaperiodate suggested that not only proteinaceous determinants are involved in the adhesion process of B. bifidum. In conclusion, it seems that the colonization strategy of this bacterium can be influenced by factors varying along the gastrointestinal tract, such as the presence of specific sugars and bile salts and the pH, possibly limiting the adhesion of B. bifidum to only restricted distal sites of the gut.

  16. Protein conformation as a regulator of cell-matrix adhesion.

    PubMed

    Hytönen, Vesa P; Wehrle-Haller, Bernhard

    2014-04-14

    The dynamic regulation of cell-matrix adhesion is essential for tissue homeostasis and architecture, and thus numerous pathologies are linked to altered cell-extracellular matrix (ECM) interaction and ECM scaffold. The molecular machinery involved in cell-matrix adhesion is complex and involves both sensory and matrix-remodelling functions. In this review, we focus on how protein conformation controls the organization and dynamics of cell-matrix adhesion. The conformational changes in various adhesion machinery components are described, including examples from ECM as well as cytoplasmic proteins. The discussed mechanisms involved in the regulation of protein conformation include mechanical stress, post-translational modifications and allosteric ligand-binding. We emphasize the potential role of intrinsically disordered protein regions in these processes and discuss the role of protein networks and co-operative protein interactions in the formation and consolidation of cell-matrix adhesion and extracellular scaffolds.

  17. Ultraweak sugar-sugar interactions for transient cell adhesion.

    PubMed Central

    Pincet, F; Le Bouar, T; Zhang, Y; Esnault, J; Mallet, J M; Perez, E; Sinaÿ, P

    2001-01-01

    Carbohydrate-carbohydrate interactions are rarely considered in biologically relevant situations such as cell recognition and adhesion. One Ca(2+)-mediated homotypic interaction between two Lewis(x) determinants (Le(x)) has been proposed to drive cell adhesion in murine embryogenesis. Here, we confirm the existence of this specific interaction by reporting the first direct quantitative measurements in an environment akin to that provided by membranes. The adhesion between giant vesicles functionalized with Le(x) was obtained by micropipette aspiration and contact angle measurements. This interaction is below the thermal energy, and cell-cell adhesion will require a large number of molecules, as illustrated by the Le(x) concentration peak observed at the cell membranes during the morula stage of the embryo. This adhesion is ultralow and therefore difficult to measure. Such small interactions explain why the concept of specific interactions between carbohydrates is often neglected. PMID:11222296

  18. Regulation of cell motile behavior by crosstalk between cadherin- and integrin-mediated adhesions.

    PubMed

    Borghi, Nicolas; Lowndes, Molly; Maruthamuthu, Venkat; Gardel, Margaret L; Nelson, W James

    2010-07-27

    During normal development and in disease, cohesive tissues undergo rearrangements that require integration of signals from cell adhesions to neighboring cells and to the extracellular matrix (ECM). How a range of cell behaviors is coordinated by these different adhesion complexes is unknown. To analyze epithelial cell motile behavior in response to combinations of cell-ECM and cell-cell adhesion cues, we took a reductionist approach at the single-cell scale by using unique, functionalized micropatterned surfaces comprising alternating stripes of ECM (collagenIV) and adjustable amounts of E-cadherin-Fc (EcadFc). On these surfaces, individual cells spatially segregated integrin- and cadherin-based complexes between collagenIV and EcadFc surfaces, respectively. Cell migration required collagenIV and did not occur on surfaces functionalized with only EcadFc. However, E-cadherin adhesion dampened lamellipodia activity on both collagenIV and EcadFc surfaces and biased the direction of cell migration without affecting the migration rate, all in an EcadFc concentration-dependent manner. Traction force microscopy showed that spatial confinement of integrin-based adhesions to collagenIV stripes induced anisotropic cell traction on collagenIV and migration directional bias. Selective depletion of different pools of alphaE-catenin, an E-cadherin and actin binding protein, identified a membrane-associated pool required for E-cadherin-mediated adhesion and down-regulation of lamellipodia activity and a cytosolic pool that down-regulated the migration rate in an E-cadherin adhesion-independent manner. These results demonstrate that there is crosstalk between E-cadherin- and integrin-based adhesion complexes and that E-cadherin regulates lamellipodia activity and cell migration directionality, but not cell migration rate.

  19. Adhesive interactions of N-cadherin limit the recruitment of microtubules to cell-cell contacts through organization of actomyosin.

    PubMed

    Plestant, Charlotte; Strale, Pierre-Olivier; Seddiki, Rima; Nguyen, Emmanuelle; Ladoux, Benoit; Mège, René-Marc

    2014-04-15

    Adhesive interactions of cadherins induce crosstalk between adhesion complexes and the actin cytoskeleton, allowing strengthening of adhesions and cytoskeletal organization. The underlying mechanisms are not completely understood, and microtubules (MTs) might be involved, as for integrin-mediated cell-extracellular-matrix adhesions. Therefore, we investigated the relationship between N-cadherin and MTs by analyzing the influence of N-cadherin engagement on MT distribution and dynamics. MTs progressed less, with a lower elongation rate, towards cadherin adhesions than towards focal adhesions. Increased actin treadmilling and the presence of an actomyosin contractile belt, suggested that actin relays inhibitory signals from cadherin adhesions to MTs. The reduced rate of MT elongation, associated with reduced recruitment of end-binding (EB) proteins to plus ends, was alleviated by expression of truncated N-cadherin, but was only moderately affected when actomyosin was disrupted. By contrast, destabilizing actomyosin fibers allowed MTs to enter the adhesion area, suggesting that tangential actin bundles impede MT growth independently of MT dynamics. Blocking MT penetration into the adhesion area strengthened cadherin adhesions. Taken together, these results establish a crosstalk between N-cadherin, F-actin and MTs. The opposing effects of cadherin and integrin engagement on actin organization and MT distribution might induce bias of the MT network during cell polarization.

  20. Cleavage and Cell Adhesion Properties of Human Epithelial Cell Adhesion Molecule (HEPCAM)*

    PubMed Central

    Tsaktanis, Thanos; Kremling, Heidi; Pavšič, Miha; von Stackelberg, Ricarda; Mack, Brigitte; Fukumori, Akio; Steiner, Harald; Vielmuth, Franziska; Spindler, Volker; Huang, Zhe; Jakubowski, Jasmine; Stoecklein, Nikolas H.; Luxenburger, Elke; Lauber, Kirsten; Lenarčič, Brigita; Gires, Olivier

    2015-01-01

    Human epithelial cell adhesion molecule (HEPCAM) is a tumor-associated antigen frequently expressed in carcinomas, which promotes proliferation after regulated intramembrane proteolysis. Here, we describe extracellular shedding of HEPCAM at two α-sites through a disintegrin and metalloprotease (ADAM) and at one β-site through BACE1. Transmembrane cleavage by γ-secretase occurs at three γ-sites to generate extracellular Aβ-like fragments and at two ϵ-sites to release human EPCAM intracellular domain HEPICD, which is efficiently degraded by the proteasome. Mapping of cleavage sites onto three-dimensional structures of HEPEX cis-dimer predicted conditional availability of α- and β-sites. Endocytosis of HEPCAM warrants acidification in cytoplasmic vesicles to dissociate protein cis-dimers required for cleavage by BACE1 at low pH values. Intramembrane cleavage sites are accessible and not part of the structurally important transmembrane helix dimer crossing region. Surprisingly, neither chemical inhibition of cleavage nor cellular knock-out of HEPCAM using CRISPR-Cas9 technology impacted the adhesion of carcinoma cell lines. Hence, a direct function of HEPCAM as an adhesion molecule in carcinoma cells is not supported and appears to be questionable. PMID:26292218

  1. Chemically programmed cell adhesion with membrane-anchored oligonucleotides

    PubMed Central

    Selden, Nicholas S.; Todhunter, Michael E.; Jee, Noel Y.; Liu, Jennifer S.; Broaders, Kyle E.; Gartner, Zev J.

    2012-01-01

    Cell adhesion organizes the structures of tissues and mediates their mechanical, chemical, and electrical integration with their surroundings. Here, we describe a strategy for chemically controlling cell adhesion using membrane anchored single-stranded DNA oligonucleotides. The reagents are pure chemical species prepared from phosphoramidites synthesized in a single chemical step from commercially available starting materials. The approach enables rapid, efficient, tunable cell adhesion, independent of proteins or glycans, by facilitating interactions with complementary labeled surfaces or other cells. We demonstrate the utility of this approach by imaging drug-induced changes in the membrane dynamics of non-adherent human cells while chemically immobilized on a passivated glass surface. PMID:22176556

  2. Characterization of human leukocyte-HUVEC adhesion: Effect of cell preparation methods.

    PubMed

    Marino, Franca; Schembri, Laura; Rasini, Emanuela; Pinoli, Monica; Scanzano, Angela; Luini, Alessandra; Congiu, Terenzio; Cosentino, Marco

    2017-04-01

    Sample manipulation to obtain isolated granulocytes represents a key, and often necessary, step in the in vitro studies. We investigated by the means of flow cytometry and microscopic techniques (both optical microscopy [OM] and scanning electron microscopy [SEM]), the granulocyte-endothelium adhesion and the role of sample manipulation. By means of a co-culture method, we have analysed the adhesion of human leukocytes, originated from two different blood samples (fresh venous blood [FB] and buffy coat [BC]), to the human umbilical venous endothelial cell (HUVEC) monolayer. Cultured HUVEC were analysed for adhesion molecule expression by means of flow cytometry, while the morphological changes were evaluated by means of SEM. Cell adhesion was evaluated by means of flow cytometry and both OM and SEM. HUVEC expressed under resting conditions the adhesion molecules ICAM-1, VCAM-1 and E-selectin and their expression was upregulated by stimulation with TNF-α (0.1-10ng/ml) as well as with LPS (1μg/ml). SEM analysis showed that stimulation with both stimuli profoundly affect cell morphology. Flow cytometric evaluation of cell adhesion showed that the ability of cells to adhere to HUVEC monolayer was quite different in the two preparations, with the lowest adhesion for FB in all the cell subsets analysed. Finally, isolated granulocytes were able to adhere to HUVEC monolayer more than cells identified in FB or BC and the adhesion was increased during activation of HUVEC with 10ng/ml of TNF-α. Our data showed that cell manipulation necessary for the isolation of specific immune cells from whole blood profoundly affect the ability of these cells to adhere to the HUVEC monolayer although their functional properties remain unchanged. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Cell adhesion to plasma-coated PVC.

    PubMed

    Rangel, Elidiane C; de Souza, Eduardo S; de Moraes, Francine S; Duek, Eliana A R; Lucchesi, Carolina; Schreiner, Wido H; Durrant, Steven F; Cruz, Nilson C

    2014-01-01

    To produce environments suitable for cell culture, thin polymer films were deposited onto commercial PVC plates from radiofrequency acetylene-argon plasmas. The proportion of argon in the plasmas, P(Ar), was varied from 5.3 to 65.8%. The adhesion and growth of Vero cells on the coated surfaces were examined for different incubation times. Cytotoxicity tests were performed using spectroscopic methods. Carbon, O, and N were detected in all the samples using XPS. Roughness remained almost unchanged in the samples prepared with 5.3 and 28.9% but tended to increase for the films deposited with P(Ar) between 28.9 and 55.3%. Surface free energy increased with increasing P(Ar), except for the sample prepared at 28.9% of Ar, which presented the least reactive surface. Cells proliferated on all the samples, including the bare PVC. Independently of the deposition condition there was no evidence of cytotoxicity, indicating the viability of such coatings for designing biocompatible devices.

  4. Cell Adhesion to Plasma-Coated PVC

    PubMed Central

    Rangel, Elidiane C.; de Souza, Eduardo S.; de Moraes, Francine S.; Duek, Eliana A. R.; Lucchesi, Carolina; Schreiner, Wido H.; Durrant, Steven F.; Cruz, Nilson C.

    2014-01-01

    To produce environments suitable for cell culture, thin polymer films were deposited onto commercial PVC plates from radiofrequency acetylene-argon plasmas. The proportion of argon in the plasmas, PAr, was varied from 5.3 to 65.8%. The adhesion and growth of Vero cells on the coated surfaces were examined for different incubation times. Cytotoxicity tests were performed using spectroscopic methods. Carbon, O, and N were detected in all the samples using XPS. Roughness remained almost unchanged in the samples prepared with 5.3 and 28.9% but tended to increase for the films deposited with PAr between 28.9 and 55.3%. Surface free energy increased with increasing PAr, except for the sample prepared at 28.9% of Ar, which presented the least reactive surface. Cells proliferated on all the samples, including the bare PVC. Independently of the deposition condition there was no evidence of cytotoxicity, indicating the viability of such coatings for designing biocompatible devices. PMID:25247202

  5. Adhesion

    MedlinePlus

    ... the intestines, adhesions can cause partial or complete bowel obstruction . Adhesions inside the uterine cavity, called Asherman syndrome , ... 1. Read More Appendicitis Asherman syndrome Glaucoma Infertility Intestinal obstruction Review Date 4/5/2016 Updated by: Irina ...

  6. Adhesions

    MedlinePlus

    Adhesions are bands of scar-like tissue. Normally, internal tissues and organs have slippery surfaces so they can shift easily as the body moves. Adhesions cause tissues and organs to stick together. They ...

  7. Friction-controlled traction force in cell adhesion.

    PubMed

    Pompe, Tilo; Kaufmann, Martin; Kasimir, Maria; Johne, Stephanie; Glorius, Stefan; Renner, Lars; Bobeth, Manfred; Pompe, Wolfgang; Werner, Carsten

    2011-10-19

    The force balance between the extracellular microenvironment and the intracellular cytoskeleton controls the cell fate. We report a new (to our knowledge) mechanism of receptor force control in cell adhesion originating from friction between cell adhesion ligands and the supporting substrate. Adherent human endothelial cells have been studied experimentally on polymer substrates noncovalently coated with fluorescent-labeled fibronectin (FN). The cellular traction force correlated with the mobility of FN during cell-driven FN fibrillogenesis. The experimental findings have been explained within a mechanistic two-dimensional model of the load transfer at focal adhesion sites. Myosin motor activity in conjunction with sliding of FN ligands noncovalently coupled to the surface of the polymer substrates is shown to result in a controlled traction force of adherent cells. We conclude that the friction of adhesion ligands on the supporting substrate is important for mechanotransduction and cell development of adherent cells in vitro and in vivo.

  8. Eimeria bovis modulates adhesion molecule gene transcription in and PMN adhesion to infected bovine endothelial cells.

    PubMed

    Hermosilla, Carlos; Zahner, Horst; Taubert, Anja

    2006-04-01

    Eimeria bovis is an important coccidian parasite of cattle causing severe diarrhea in young animals. Its first schizogony takes place in endothelial cells of the ileum resulting in the formation of macroschizonts 14-18 days p.i. This longlasting development suggests a particular immune evasion strategy of the parasite. Here, we analyse early innate immune reactions to E. bovis by determining the adhesion of polymorphonuclear neutrophils (PMN) to infected endothelial cell layers under flow conditions and the transcription of adhesion molecule genes in infected host cells. Bovine umbilical vein endothelial cells (BUVEC) were infected with E. bovis sporozoites. Sporozoites invaded BUVEC within 1h and the first mature macroschizonts occurred 14 days p.i. PMN adhesion was enhanced in E. bovis-infected BUVEC layers as early as 8h p.i.; maximum adhesion occurred 48 h p.i. Increased adhesion rates persisted until the end of the observation period at 14 days p.i. PMN adhered to both infected and uninfected cells within monolayers, suggesting paracrine cell activation. E. bovis infection upregulated the transcription of genes encoding for P-selectin, E-selectin, vascular cellular adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1). Most marked effects concerned E-selectin followed by P-selectin, VCAM-1 and ICAM-1. Increased transcript levels were found beginning 30 min p.i. and maximum values occurred 1-2h p.i. (P-selectin) and 2-4h p.i. (E-selectin, VCAM-1, ICAM-1). By 12-24h p.i. levels had decreased to those of uninfected controls. Tumor necrosis factor alpha (TNFalpha)-induced PMN adhesion was significantly reduced in infected vs. uninfected BUVEC. Eimeria bovis also had suppressive effects on TNFalpha-mediated upregulation of adhesion molecule gene transcription. The data presented here suggest that infection of BUVEC with E. bovis on one hand induces proinflammatory reactions resulting in enhanced PMN adhesion mediated by upregulated adhesion

  9. Regulation of cell motile behavior by crosstalk between cadherin- and integrin-mediated adhesions

    PubMed Central

    Borghi, Nicolas; Lowndes, Molly; Maruthamuthu, Venkat; Gardel, Margaret L.; Nelson, W. James

    2010-01-01

    During normal development and in disease, cohesive tissues undergo rearrangements that require integration of signals from cell adhesions to neighboring cells and to the extracellular matrix (ECM). How a range of cell behaviors is coordinated by these different adhesion complexes is unknown. To analyze epithelial cell motile behavior in response to combinations of cell–ECM and cell–cell adhesion cues, we took a reductionist approach at the single-cell scale by using unique, functionalized micropatterned surfaces comprising alternating stripes of ECM (collagenIV) and adjustable amounts of E-cadherin-Fc (EcadFc). On these surfaces, individual cells spatially segregated integrin- and cadherin-based complexes between collagenIV and EcadFc surfaces, respectively. Cell migration required collagenIV and did not occur on surfaces functionalized with only EcadFc. However, E-cadherin adhesion dampened lamellipodia activity on both collagenIV and EcadFc surfaces and biased the direction of cell migration without affecting the migration rate, all in an EcadFc concentration-dependent manner. Traction force microscopy showed that spatial confinement of integrin-based adhesions to collagenIV stripes induced anisotropic cell traction on collagenIV and migration directional bias. Selective depletion of different pools of αE-catenin, an E-cadherin and actin binding protein, identified a membrane-associated pool required for E-cadherin–mediated adhesion and down-regulation of lamellipodia activity and a cytosolic pool that down-regulated the migration rate in an E-cadherin adhesion-independent manner. These results demonstrate that there is crosstalk between E-cadherin– and integrin-based adhesion complexes and that E-cadherin regulates lamellipodia activity and cell migration directionality, but not cell migration rate. PMID:20566866

  10. RGD modified polymers: biomaterials for stimulated cell adhesion and beyond.

    PubMed

    Hersel, Ulrich; Dahmen, Claudia; Kessler, Horst

    2003-11-01

    Since RGD peptides (R: arginine; G: glycine; D: aspartic acid) have been found to promote cell adhesion in 1984 (Cell attachment activity of fibronectin can be duplicated by small synthetic fragments of the molecule, Nature 309 (1984) 30), numerous materials have been RGD functionalized for academic studies or medical applications. This review gives an overview of RGD modified polymers, that have been used for cell adhesion, and provides information about technical aspects of RGD immobilization on polymers. The impacts of RGD peptide surface density, spatial arrangement as well as integrin affinity and selectivity on cell responses like adhesion and migration are discussed.

  11. Single cell adhesion assay using computer controlled micropipette.

    PubMed

    Salánki, Rita; Hős, Csaba; Orgovan, Norbert; Péter, Beatrix; Sándor, Noémi; Bajtay, Zsuzsa; Erdei, Anna; Horvath, Robert; Szabó, Bálint

    2014-01-01

    Cell adhesion is a fundamental phenomenon vital for all multicellular organisms. Recognition of and adhesion to specific macromolecules is a crucial task of leukocytes to initiate the immune response. To gain statistically reliable information of cell adhesion, large numbers of cells should be measured. However, direct measurement of the adhesion force of single cells is still challenging and today's techniques typically have an extremely low throughput (5-10 cells per day). Here, we introduce a computer controlled micropipette mounted onto a normal inverted microscope for probing single cell interactions with specific macromolecules. We calculated the estimated hydrodynamic lifting force acting on target cells by the numerical simulation of the flow at the micropipette tip. The adhesion force of surface attached cells could be accurately probed by repeating the pick-up process with increasing vacuum applied in the pipette positioned above the cell under investigation. Using the introduced methodology hundreds of cells adhered to specific macromolecules were measured one by one in a relatively short period of time (∼30 min). We blocked nonspecific cell adhesion by the protein non-adhesive PLL-g-PEG polymer. We found that human primary monocytes are less adherent to fibrinogen than their in vitro differentiated descendants: macrophages and dendritic cells, the latter producing the highest average adhesion force. Validation of the here introduced method was achieved by the hydrostatic step-pressure micropipette manipulation technique. Additionally the result was reinforced in standard microfluidic shear stress channels. Nevertheless, automated micropipette gave higher sensitivity and less side-effect than the shear stress channel. Using our technique, the probed single cells can be easily picked up and further investigated by other techniques; a definite advantage of the computer controlled micropipette. Our experiments revealed the existence of a sub-population of

  12. Single Cell Adhesion Assay Using Computer Controlled Micropipette

    PubMed Central

    Salánki, Rita; Hős, Csaba; Orgovan, Norbert; Péter, Beatrix; Sándor, Noémi; Bajtay, Zsuzsa; Erdei, Anna; Horvath, Robert; Szabó, Bálint

    2014-01-01

    Cell adhesion is a fundamental phenomenon vital for all multicellular organisms. Recognition of and adhesion to specific macromolecules is a crucial task of leukocytes to initiate the immune response. To gain statistically reliable information of cell adhesion, large numbers of cells should be measured. However, direct measurement of the adhesion force of single cells is still challenging and today’s techniques typically have an extremely low throughput (5–10 cells per day). Here, we introduce a computer controlled micropipette mounted onto a normal inverted microscope for probing single cell interactions with specific macromolecules. We calculated the estimated hydrodynamic lifting force acting on target cells by the numerical simulation of the flow at the micropipette tip. The adhesion force of surface attached cells could be accurately probed by repeating the pick-up process with increasing vacuum applied in the pipette positioned above the cell under investigation. Using the introduced methodology hundreds of cells adhered to specific macromolecules were measured one by one in a relatively short period of time (∼30 min). We blocked nonspecific cell adhesion by the protein non-adhesive PLL-g-PEG polymer. We found that human primary monocytes are less adherent to fibrinogen than their in vitro differentiated descendants: macrophages and dendritic cells, the latter producing the highest average adhesion force. Validation of the here introduced method was achieved by the hydrostatic step-pressure micropipette manipulation technique. Additionally the result was reinforced in standard microfluidic shear stress channels. Nevertheless, automated micropipette gave higher sensitivity and less side-effect than the shear stress channel. Using our technique, the probed single cells can be easily picked up and further investigated by other techniques; a definite advantage of the computer controlled micropipette. Our experiments revealed the existence of a sub

  13. Simulation of Cell Adhesion using a Particle Transport Model

    NASA Astrophysics Data System (ADS)

    Chesnutt, Jennifer

    2005-11-01

    An efficient computational method for simulation of cell adhesion through protein binding forces is discussed. In this method, the cells are represented by deformable elastic particles, and the protein binding is represented by a rate equation. The method is first developed for collision and adhesion of two similar cells impacting on each other from opposite directions. The computational method is then applied in a particle-transport model for a cloud of interacting and colliding cells, each of which are represented by particles of finite size. One application might include red blood cells adhering together to form rouleaux, which are chains of red blood cells that are found in different parts of the circulatory system. Other potential applications include adhesion of platelets to a blood vessel wall or mechanical heart valve, which is a precursor of thrombosis formation, or adhesion of cancer cells to organ walls in the lymphatic, circulatory, digestive or pulmonary systems.

  14. Effect of hydroxyapatite surface morphology on cell adhesion.

    PubMed

    Iwamoto, Takashi; Hieda, Yohki; Kogai, Yasumichi

    2016-12-01

    We obtained hydroxyapatite (HAp) materials as a block by mixing HAp nanoparticles and polymer, and then calcining the mixtures. The surface morphology of the HAp materials was tuned by varying heat treatment conditions. After calcining the mixtures at 1200 or 800°C for 4h, the surface morphology of the HAp materials was flat or convexo-concave, respectively. The flat surface morphology, which showed micrometer-ordered grain boundaries, was formed by the aggregation of HAp nanoparticles. On the other hand, the convexo-concave surface morphology resulted from the agglomeration of HAp nanoparticles after heat treatment at 800°C for 4h with nanometer-ordered particle size. We tested cell adhesion to HAp materials with flat or convexo-concave surface morphology and found that cells adhered well to the flat HAp materials but not to the convexo-concave HAp materials. This technique for selectively preparing HAp materials with flat or convexo-concave surface morphology was very easy because we merely mixed commercial HAp nanoparticles with polymer and then calcined the mixtures. As a result, the heat treatment temperature affected the surface morphology of our HAp materials, and their surface morphologies contributed to cell adhesion independently of other material properties.

  15. Amygdalin influences bladder cancer cell adhesion and invasion in vitro.

    PubMed

    Makarević, Jasmina; Rutz, Jochen; Juengel, Eva; Kaulfuss, Silke; Tsaur, Igor; Nelson, Karen; Pfitzenmaier, Jesco; Haferkamp, Axel; Blaheta, Roman A

    2014-01-01

    The cyanogenic diglucoside amygdalin, derived from Rosaceae kernels, is employed by many patients as an alternative anti-cancer treatment. However, whether amygdalin indeed acts as an anti-tumor agent is not clear. Metastasis blocking properties of amygdalin on bladder cancer cell lines was, therefore, investigated. Amygdalin (10 mg/ml) was applied to UMUC-3, TCCSUP or RT112 bladder cancer cells for 24 h or for 2 weeks. Tumor cell adhesion to vascular endothelium or to immobilized collagen as well as tumor cell migration was examined. Effects of drug treatment on integrin α and β subtypes, on integrin-linked kinase (ILK) and total and activated focal adhesion kinase (FAK) were also determined. Integrin knock-down was carried out to evaluate integrin influence on migration and adhesion. A 24 h or 2 week amygdalin application distinctly reduced tumor cell adhesion and migration of UMUC-3 and RT112 cells. TCCSUP adhesion was also reduced, but migration was elevated under amygdalin. Integrin subtype expression was significantly and specifically altered by amygdalin depending on the cell line. ILK was moderately, and activated FAK strongly, lost in all tumor cell lines in the presence of amygdalin. Knock down of β1 integrin caused a significant decrease in both adhesion and migration of UMUC-3 cells, but a significant increase in TCCSUP adhesion. Knock down of β4 integrin caused a significant decrease in migration of RT112 cells. Since the different actions of amygdalin on the different cell lines was mirrored by β1 or β4 knock down, it is postulated that amygdalin influences adhesion and migratory properties of bladder cancer cells by modulating β1 or β4 integrin expression. The amygdalin induced increase in TCCSUP migratory behavior indicates that any anti-tumor benefits from amygdalin (seen with the other two cell lines) may depend upon the cancer cell type.

  16. Amygdalin Influences Bladder Cancer Cell Adhesion and Invasion In Vitro

    PubMed Central

    Makarević, Jasmina; Rutz, Jochen; Juengel, Eva; Kaulfuss, Silke; Tsaur, Igor; Nelson, Karen; Pfitzenmaier, Jesco

    2014-01-01

    The cyanogenic diglucoside amygdalin, derived from Rosaceae kernels, is employed by many patients as an alternative anti-cancer treatment. However, whether amygdalin indeed acts as an anti-tumor agent is not clear. Metastasis blocking properties of amygdalin on bladder cancer cell lines was, therefore, investigated. Amygdalin (10 mg/ml) was applied to UMUC-3, TCCSUP or RT112 bladder cancer cells for 24 h or for 2 weeks. Tumor cell adhesion to vascular endothelium or to immobilized collagen as well as tumor cell migration was examined. Effects of drug treatment on integrin α and β subtypes, on integrin-linked kinase (ILK) and total and activated focal adhesion kinase (FAK) were also determined. Integrin knock-down was carried out to evaluate integrin influence on migration and adhesion. A 24 h or 2 week amygdalin application distinctly reduced tumor cell adhesion and migration of UMUC-3 and RT112 cells. TCCSUP adhesion was also reduced, but migration was elevated under amygdalin. Integrin subtype expression was significantly and specifically altered by amygdalin depending on the cell line. ILK was moderately, and activated FAK strongly, lost in all tumor cell lines in the presence of amygdalin. Knock down of β1 integrin caused a significant decrease in both adhesion and migration of UMUC-3 cells, but a significant increase in TCCSUP adhesion. Knock down of β4 integrin caused a significant decrease in migration of RT112 cells. Since the different actions of amygdalin on the different cell lines was mirrored by β1 or β4 knock down, it is postulated that amygdalin influences adhesion and migratory properties of bladder cancer cells by modulating β1 or β4 integrin expression. The amygdalin induced increase in TCCSUP migratory behavior indicates that any anti-tumor benefits from amygdalin (seen with the other two cell lines) may depend upon the cancer cell type. PMID:25333694

  17. Iron ion irradiation increases promotes adhesion of monocytic cells to arterial vascular endothelium

    NASA Astrophysics Data System (ADS)

    Kucik, Dennis; Khaled, Saman; Gupta, Kiran; Wu, Xing; Yu, Tao; Chang, Polly; Kabarowski, Janusz

    Radiation causes inflammation, and chronic, low-level vascular inflammation is a risk factor for atherosclerosis. Consistent with this, exposure to radiation from a variety of sources is associated with increased risk of heart disease and stroke. Part of the inflammatory response to radiation is a change in the adhesiveness of the endothelial cells that line the blood vessels, triggering inappropriate accumulation of leukocytes, leading to later, damaging effects of inflammation. Although some studies have been done on the effects of gamma irradiation on vascular endothelium, the response of endothelium to heavy ion radiation likely to be encountered in prolonged space flight has not been determined. We investigated how irradiation of aortic endothelial cells with iron ions affects adhesiveness of cultured aortic endothelial cells for monocytic cells and the consequences of this for development of atherosclerosis. Aortic endothelial cells were irradiated with 600 MeV iron ions at Brookhaven National Laboratory and adhesion-related changes were measured. Cells remained viable for at least 72 hours, and were even able to repair acute damage to cell junctions. We found that iron ion irradiation altered expression levels of specific endothelial cell adhesion molecules. Further, these changes had functional consequences. Using a flow chamber adhesion assay to measure adhesion of monocytic cells to endothelial cells under physiological shear stress, we found that adhesivity of vascular endothelium was enhanced in as little as 24 hours after irradiation. Further, the radiation dose dependence was not monotonic, suggesting that it was not simply the result of endothelial cell damage. We also irradiated aortic arches and carotid arteries of Apolipoprotein-E-deficient mice. Histologic analysis of these mice will be conducted to determine whether effects of radiation on endothelial adhesiveness result in consequences for development of atherosclerosis. (Supported by NSBRI

  18. Hydrogen peroxide regulates cell adhesion through the redox sensor RPSA.

    PubMed

    Vilas-Boas, Filipe; Bagulho, Ana; Tenente, Rita; Teixeira, Vitor H; Martins, Gabriel; da Costa, Gonçalo; Jerónimo, Ana; Cordeiro, Carlos; Machuqueiro, Miguel; Real, Carla

    2016-01-01

    To become metastatic, a tumor cell must acquire new adhesion properties that allow migration into the surrounding connective tissue, transmigration across endothelial cells to reach the blood stream and, at the site of metastasis, adhesion to endothelial cells and transmigration to colonize a new tissue. Hydrogen peroxide (H2O2) is a redox signaling molecule produced in tumor cell microenvironment with high relevance for tumor development. However, the molecular mechanisms regulated by H2O2 in tumor cells are still poorly known. The identification of H2O2-target proteins in tumor cells and the understanding of their role in tumor cell adhesion are essential for the development of novel redox-based therapies for cancer. In this paper, we identified Ribosomal Protein SA (RPSA) as a target of H2O2 and showed that RPSA in the oxidized state accumulates in clusters that contain specific adhesion molecules. Furthermore, we showed that RPSA oxidation improves cell adhesion efficiency to laminin in vitro and promotes cell extravasation in vivo. Our results unravel a new mechanism for H2O2-dependent modulation of cell adhesion properties and identify RPSA as the H2O2 sensor in this process. This work indicates that high levels of RPSA expression might confer a selective advantage to tumor cells in an oxidative environment.

  19. Nanomechanical measurement of adhesion and migration of leukemia cells with phorbol 12-myristate 13-acetate treatment.

    PubMed

    Zhou, Zhuo Long; Ma, Jing; Tong, Ming-Hui; Chan, Barbara Pui; Wong, Alice Sze Tsai; Ngan, Alfonso Hing Wan

    The adhesion and traction behavior of leukemia cells in their microenvironment is directly linked to their migration, which is a prime issue affecting the release of cancer cells from the bone marrow and hence metastasis. In assessing the effectiveness of phorbol 12-myristate 13-acetate (PMA) treatment, the conventional batch-cell transwell-migration assay may not indicate the intrinsic effect of the treatment on migration, since the treatment may also affect other cellular behavior, such as proliferation or death. In this study, the pN-level adhesion and traction forces between single leukemia cells and their microenvironment were directly measured using optical tweezers and traction-force microscopy. The effects of PMA on K562 and THP1 leukemia cells were studied, and the results showed that PMA treatment significantly increased cell adhesion with extracellular matrix proteins, bone marrow stromal cells, and human fibroblasts. PMA treatment also significantly increased the traction of THP1 cells on bovine serum albumin proteins, although the effect on K562 cells was insignificant. Western blots showed an increased expression of E-cadherin and vimentin proteins after the leukemia cells were treated with PMA. The study suggests that PMA upregulates adhesion and thus suppresses the migration of both K562 and THP1 cells in their microenvironment. The ability of optical tweezers and traction-force microscopy to measure directly pN-level cell-protein or cell-cell contact was also demonstrated.

  20. Shark cartilage extract interferes with cell adhesion and induces reorganization of focal adhesions in cultured endothelial cells.

    PubMed

    Chen, J S; Chang, C M; Wu, J C; Wang, S M

    2000-06-06

    In this study, we examined the effects of shark cartilage extract on the attachment and spreading properties and the focal adhesion structure of cultured bovine pulmonary artery endothelial cells. Treatment with cartilage extract resulted in cell detachment from the substratum. Immunofluorescence staining of those treated cells that remained attached showed that, instead of being present in both central and peripheral focal adhesions as in control cells, both integrin alpha(v)beta(3) and vinculin were found only in peripheral focal adhesion and thinner actin filament bundles were seen. In addition to causing cell detachment, cartilage extract partially inhibited the initial adherence of the cells to the substratum in a dose-dependent manner. Integrin alpha(v)beta(3) and vinculin staining of these cells also showed a peripheral focal adhesion distribution pattern. Vitronectin induced cell spreading in the absence of serum, but was blocked by simultaneous incubation with cartilage extract, which was shown to inhibit both integrin alpha(v)beta(3) and vinculin recruitment to focal adhesion and the formation of stress fibers. Dot binding assays showed that these inhibitory effects on cell attachment and spreading were not due to direct binding of cartilage extract components to integrin alpha(v)beta(3) or vitronectin. Shark cartilage chondroitin sulfate had no inhibitory effect on either cell attachment or spreading of endothelial cells. These results show that the inhibitory effects of cartilage extract on cell attachment and spreading are mediated by modification of the organization of focal adhesion proteins.

  1. FGFR4 Downregulation of Cell Adhesion in Prostate Cancer

    DTIC Science & Technology

    2007-03-01

    AD_________________ Award Number: W81XWH-06-1-0385 TITLE: FGFR4 Downregulation of Cell Adhesion...2007 2. REPORT TYPE Annual 3. DATES COVERED 1 Mar 2006 – 28 Feb 2007 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER FGFR4 Downregulation of Cell...our project to examine the role of FGFR4 G388R in altering cell adhesion in prostate cancer. This includes acquiring expertise in the passage and

  2. Transcriptionally Regulated Cell Adhesion Network Dictates Distal Tip Cell Directionality

    PubMed Central

    Wong, Ming-Ching; Kennedy, William P.; Schwarzbauer, Jean E.

    2015-01-01

    Background The mechanisms that govern directional changes in cell migration are poorly understood. The migratory paths of two distal tip cells (DTC) determine the U-shape of the C. elegans hermaphroditic gonad. The morphogenesis of this organ provides a model system to identify genes necessary for the DTCs to execute two stereotyped turns. Results Using candidate genes for RNAi knockdown in a DTC-specific strain, we identified two transcriptional regulators required for DTC turning: cbp-1, the CBP/p300 transcriptional coactivator homologue, and let-607, a CREBH transcription factor homologue. Further screening of potential target genes uncovered a network of integrin adhesion-related genes that have roles in turning and are dependent on cbp-1 and let-607 for expression. These genes include src-1/Src kinase, tln-1/talin, pat-2/α integrin and nmy-2, a nonmuscle myosin heavy chain. Conclusions Transcriptional regulation by means of cbp-1 and let-607 is crucial for determining directional changes during DTC migration. These regulators coordinate a gene network that is necessary for integrin-mediated adhesion. Overall, these results suggest that directional changes in cell migration rely on the precise gene regulation of adhesion. PMID:24811939

  3. Cell adhesion to borate glasses by colloidal probe microscopy.

    PubMed

    Wiederhorn, Sheldon M; Chae, Young-Hun; Simon, Carl G; Cahn, Jackson; Deng, Yan; Day, Delbert

    2011-05-01

    The adhesion of osteoblast-like cells to silicate and borate glasses was measured in cell growth medium using colloidal probe microscopy. The probes consisted of silicate and borate glass spheres, 25-50 μm in diameter, attached to atomic force microscope cantilevers. Variables of the study included glass composition and time of contact of the cell to the glasses. Increasing the time of contact from 15 to 900 s increased the force of adhesion. The data could be plotted linearly on a log-log plot of adhesive force versus time. Of the seven glasses tested, five had slopes close to 0.5, suggesting a square root dependence of the adhesive force on the contact time. Such behavior can be interpreted as a diffusion limited process occurring during the early stages of cell attachment. We suggest that the rate limiting step in the adhesion process is the diffusion of integrins resident in the cell membrane to the area of cell attachment. Data presented in this paper support the hypothesis of Hench et al. that strong adhesion depends on the formation of a calcium phosphate reaction layer on the surfaces of the glass. Glasses that did not form a calcium phosphate layer exhibited a weaker adhesive force relative to those glasses that did form a calcium phosphate layer.

  4. Novel Roles of the Chemorepellent Axon Guidance Molecule RGMa in Cell Migration and Adhesion

    PubMed Central

    Lah, Grace J.

    2012-01-01

    The repulsive guidance molecule A (RGMa) is a contact-mediated axon guidance molecule that has significant roles in central nervous system (CNS) development. Here we have examined whether RGMa has novel roles in cell migration and cell adhesion outside the nervous system. RGMa was found to stimulate cell migration from Xenopus animal cap explants in a neogenin-dependent and BMP-independent manner. RGMa also stimulated the adhesion of Xenopus animal cap cells, and this adhesion was dependent on neogenin and independent of calcium. To begin to functionally characterize the role of specific domains in RGMa, we assessed the migratory and adhesive activities of deletion mutants. RGMa lacking the partial von Willebrand factor type D (vWF) domain preferentially perturbed cell adhesion, while mutants lacking the RGD motif affected cell migration. We also revealed that manipulating the levels of RGMa in vivo caused major migration defects during Xenopus gastrulation. We have revealed here novel roles of RGMa in cell migration and adhesion and demonstrated that perturbations to the homeostasis of RGMa expression can severely disrupt major morphogenetic events. These results have implications for understanding the role of RGMa in both health and disease. PMID:22215618

  5. Eosinophil adhesion under flow conditions activates mechanosensitive signaling pathways in human endothelial cells

    PubMed Central

    Cuvelier, Susan L.; Paul, Smitha; Shariat, Neda; Colarusso, Pina; Patel, Kamala D.

    2005-01-01

    Leukocyte transmigration can be affected by shear stress; however, the mechanisms by which shear stress modulates transmigration are unknown. We found that adhesion of eosinophils or an eosinophilic cell line to intereukin 4–stimulated endothelial cells led to a shear-dependent increase in endothelial cell intracellular calcium and increased phosphorylation of extracellular signal-regulated kinase (ERK) 2, but not c-Jun NH2-terminal kinase or p38 mitogen-activated protein kinase. Latex beads coated with antibodies were used to characterize the role of specific endothelial cell surface molecules in initiating signaling under shear conditions. We found that ligation of either vascular cell adhesion molecule–1 or E-selectin, but not major histocompatibility complex class I, induced a shear-dependent increase in ERK2 phosphorylation in cytokine-stimulated endothelial cells. Disassembly of the actin cytoskeleton with latrunculin A prevented ERK2 phosphorylation after adhesion under flow conditions, supporting a role for the cytoskeleton in mechanosensing. Rapid phosphorylation of focal adhesion kinase and paxillin occurred under identical conditions, suggesting that focal adhesions were also involved in mechanotransduction. Finally, we found that Rho-associated protein kinase and calpain were both critical in the subsequent transendothelial migration of eosinophils under flow conditions. These data suggest that ligation of leukocyte adhesion molecules under flow conditions leads to mechanotransduction in endothelial cells, which can regulate subsequent leukocyte trafficking. PMID:16172263

  6. Eosinophil adhesion under flow conditions activates mechanosensitive signaling pathways in human endothelial cells.

    PubMed

    Cuvelier, Susan L; Paul, Smitha; Shariat, Neda; Colarusso, Pina; Patel, Kamala D

    2005-09-19

    Leukocyte transmigration can be affected by shear stress; however, the mechanisms by which shear stress modulates transmigration are unknown. We found that adhesion of eosinophils or an eosinophilic cell line to intereukin 4-stimulated endothelial cells led to a shear-dependent increase in endothelial cell intracellular calcium and increased phosphorylation of extracellular signal-regulated kinase (ERK) 2, but not c-Jun NH2-terminal kinase or p38 mitogen-activated protein kinase. Latex beads coated with antibodies were used to characterize the role of specific endothelial cell surface molecules in initiating signaling under shear conditions. We found that ligation of either vascular cell adhesion molecule-1 or E-selectin, but not major histocompatibility complex class I, induced a shear-dependent increase in ERK2 phosphorylation in cytokine-stimulated endothelial cells. Disassembly of the actin cytoskeleton with latrunculin A prevented ERK2 phosphorylation after adhesion under flow conditions, supporting a role for the cytoskeleton in mechano-sensing. Rapid phosphorylation of focal adhesion kinase and paxillin occurred under identical conditions, suggesting that focal adhesions were also involved in mechanotransduction. Finally, we found that Rho-associated protein kinase and calpain were both critical in the subsequent transendothelial migration of eosinophils under flow conditions. These data suggest that ligation of leukocyte adhesion molecules under flow conditions leads to mechanotransduction in endothelial cells, which can regulate subsequent leukocyte trafficking.

  7. Shedding of APP limits its synaptogenic activity and cell adhesion properties

    PubMed Central

    Stahl, Ronny; Schilling, Sandra; Soba, Peter; Rupp, Carsten; Hartmann, Tobias; Wagner, Katja; Merdes, Gunter; Eggert, Simone; Kins, Stefan

    2014-01-01

    The amyloid precursor protein (APP) plays a central role in Alzheimer’s disease (AD) and has essential synapse promoting functions. Synaptogenic activity as well as cell adhesion properties of APP presumably depend on trans-cellular dimerization via its extracellular domain. Since neuronal APP is extensively processed by secretases, it raises the question if APP shedding affects its cell adhesion and synaptogenic properties. We show that inhibition of APP shedding using cleavage deficient forms of APP or a dominant negative α-secretase strongly enhanced its cell adhesion and synaptogenic activity suggesting that synapse promoting function of APP is tightly regulated by α-secretase mediated processing, similar to other trans-cellular synaptic adhesion molecules. PMID:25520622

  8. Amine-functionalized polypyrrole: Inherently cell adhesive conducting polymer.

    PubMed

    Lee, Jae Y; Schmidt, Christine E

    2015-06-01

    Electrically conducting polymers (CPs) have been recognized as novel biomaterials that can electrically communicate with biological systems. For their tissue engineering applications, CPs have been modified to promote cell adhesion for improved interactions between biomaterials and cells/tissues. Conventional approaches to improve cell adhesion involve the surface modification of CPs with biomolecules, such as physical adsorption of cell adhesive proteins and polycationic polymers, or their chemical immobilization; however, these approaches require additional multiple modification steps with expensive biomolecules. In this study, as a simple and effective alternative to such additional biomolecule treatment, we synthesized amine-functionalized polypyrrole (APPy) that inherently presents cell adhesion-supporting positive charges under physiological conditions. The synthesized APPy provides electrical activity in a moderate range and a hydrophilic surface compared to regular polypyrrole (PPy) homopolymers. Under both serum and serum-free conditions, APPy exhibited superior attachment of human dermal fibroblasts and Schwann cells compared to PPy homopolymer controls. Moreover, Schwann cell adhesion onto the APPy copolymer was at least similar to that on poly-l-lysine treated PPy controls. Our results indicate that amine-functionalized CP substrates will be useful to achieve good cell adhesion and potentially electrically stimulate various cells. In addition, amine functionality present on CPs can further serve as a novel and flexible platform to chemically tether various bioactive molecules, such as growth factors, antibodies, and chemical drugs. © 2014 Wiley Periodicals, Inc.

  9. Amine-functionalized polypyrrole: inherently cell adhesive conducting polymer

    PubMed Central

    Lee, Jae Y.; Schmidt, Christine E.

    2014-01-01

    Electrically conducting polymers have been recognized as novel biomaterials that can electrically communicate with biological systems. For their tissue engineering applications, conducting polymers have been modified to promote cell adhesion for improved interactions between biomaterials and cells/tissues. Conventional approaches to improve cell adhesion involve the surface modification of conducting polymers with biomolecules, such as physical adsorption of cell adhesive proteins and polycationic polymers, or their chemical immobilization; however, these approaches require additional multiple modification steps with expensive biomolecules. In this study, as a simple and effective alternative to such additional biomolecule treatment, we synthesized amine-functionalized polypyrrole (APPy) that inherently presents cell adhesion-supporting positive charges under physiological conditions. The synthesized APPy provides electrical activity in a moderate range and a hydrophilic surface compared to regular polypyrrole (PPy) homopolymers. Under both serum and serum-free conditions, APPy exhibited superior attachment of human dermal fibroblasts and Schwann cells compared to PPy homopolymer controls. Moreover, Schwann cell adhesion onto the APPy copolymer was at least similar to that on poly-L-lysine treated PPy controls. Our results indicate that amine-functionalized conducting polymer substrates will be useful to achieve good cell adhesion and potentially electrically stimulate various cells. In addition, an amine functionality present on conducting polymers can further serve as a novel and flexible platform to chemically tether various bioactive molecules, such as growth factors, antibodies, and chemical drugs. PMID:25294089

  10. Leukocyte adhesion deficiency-III is caused by mutations in KINDLIN3 affecting integrin activation

    PubMed Central

    Svensson, Lena; Howarth, Kimberley; McDowall, Alison; Patzak, Irene; Evans, Rachel; Ussar, Siegfried; Moser, Markus; Metin, Ayse; Fried, Mike; Tomlinson, Ian; Hogg, Nancy

    2009-01-01

    Integrins are the major adhesion receptors of leukocytes and platelets. β1 and β2 integrin function on leukocytes is crucial for a successful immune response and the platelet integrin αIIbβ3 initiates the process of blood clotting through binding fibrinogen1-3. Integrins on circulating cells bind poorly to their ligands but become active after ‘inside-out’ signaling through other membrane receptors4,5. Subjects with leukocyte adhesion deficiency-1 (LAD-I) do not express β2 integrins because of mutations in the gene specifying the β2 subunit, and they suffer recurrent bacterial infections6,7. Mutations affecting αIIbβ3 integrin cause the bleeding disorder termed Glanzmann’s thrombasthenia3. Subjects with LAD-III show symptoms of both LAD-I and Glanzmann’s thrombasthenia. Their hematopoietically-derived cells express β1, β2 and β3 integrins, but defective inside-out signaling causes immune deficiency and bleeding problems8. The LAD-III lesion has been attributed to a C→A mutation in the gene encoding calcium and diacylglycerol guanine nucleotide exchange factor (CALDAGGEF1; official symbol RASGRP2) specifying the CALDAG-GEF1 protein9, but we show that this change is not responsible for the LAD-III disorder. Instead, we identify mutations in the KINDLIN3 (official symbol FERMT3) gene specifying the KINDLIN-3 protein as the cause of LAD-III in Maltese and Turkish subjects. Two independent mutations result in decreased KINDLIN3 messenger RNA levels and loss of protein expression. Notably, transfection of the subjects’ lymphocytes with KINDLIN3 complementary DNA but not CALDAGGEF1 cDNA reverses the LAD-III defect, restoring integrin-mediated adhesion and migration. PMID:19234463

  11. Dissecting cell adhesion architecture using advanced imaging techniques

    PubMed Central

    Morton, Penny E

    2011-01-01

    Cell adhesion to extracellular matrix proteins or to other cells is essential for the control of embryonic development, tissue integrity, immune function and wound healing. Adhesions are tightly spatially regulated structures containing over one hundred different proteins that coordinate both dynamics and signaling events at these sites. Extensive biochemical and morphological analysis of adhesion types over the past three decades has greatly improved understanding of individual protein contributions to adhesion signaling and, in some cases, dynamics. However, it is becoming increasingly clear that these diverse macromolecular complexes contain a variety of protein sub-networks, as well as distinct sub-domains that likely play important roles in regulating adhesion behavior. Until recently, resolving these structures, which are often less than a micron in size, was hampered by the limitations of conventional light microscopy. However, recent advances in optical techniques and imaging methods have revealed exciting insight into the intricate control of adhesion structure and assembly. Here we provide an overview of the recent data arising from such studies of cell:matrix and cell:cell contact and an overview of the imaging strategies that have been applied to study the intricacies and hierarchy of proteins within adhesions. PMID:21785274

  12. Nanomechanical measurement of adhesion and migration of leukemia cells with phorbol 12-myristate 13-acetate treatment

    PubMed Central

    Zhou, Zhuo Long; Ma, Jing; Tong, Ming-Hui; Chan, Barbara Pui; Wong, Alice Sze Tsai; Ngan, Alfonso Hing Wan

    2016-01-01

    The adhesion and traction behavior of leukemia cells in their microenvironment is directly linked to their migration, which is a prime issue affecting the release of cancer cells from the bone marrow and hence metastasis. In assessing the effectiveness of phorbol 12-myristate 13-acetate (PMA) treatment, the conventional batch-cell transwell-migration assay may not indicate the intrinsic effect of the treatment on migration, since the treatment may also affect other cellular behavior, such as proliferation or death. In this study, the pN-level adhesion and traction forces between single leukemia cells and their microenvironment were directly measured using optical tweezers and traction-force microscopy. The effects of PMA on K562 and THP1 leukemia cells were studied, and the results showed that PMA treatment significantly increased cell adhesion with extracellular matrix proteins, bone marrow stromal cells, and human fibroblasts. PMA treatment also significantly increased the traction of THP1 cells on bovine serum albumin proteins, although the effect on K562 cells was insignificant. Western blots showed an increased expression of E-cadherin and vimentin proteins after the leukemia cells were treated with PMA. The study suggests that PMA upregulates adhesion and thus suppresses the migration of both K562 and THP1 cells in their microenvironment. The ability of optical tweezers and traction-force microscopy to measure directly pN-level cell–protein or cell–cell contact was also demonstrated. PMID:27994457

  13. Androgen exposure increases human monocyte adhesion to vascular endothelium and endothelial cell expression of vascular cell adhesion molecule-1.

    PubMed

    McCrohon, J A; Jessup, W; Handelsman, D J; Celermajer, D S

    1999-05-04

    Male sex is an independent risk factor for coronary artery disease. Owing to the importance of monocyte adhesion to endothelial cells in the development of atherosclerosis, we hypothesized that androgens might promote this process. We therefore studied the effects of the nonaromatizable androgen dihydrotestosterone (DHT) on human monocyte adhesion to human endothelial cells and on endothelial cell-surface expression of adhesion molecules. Human umbilical vein endothelial cells (HUVECs) were grown to confluence in media supplemented with postmenopausal female serum, then exposed for 48 hours to either DHT (40 and 400 nmol/L), with or without the androgen receptor blocker hydroxyflutamide (HF) (4 micromol/L); HF alone; or vehicle control (ethanol 0.1%). Human monocytes obtained by elutriation were incubated for 1 hour with the HUVECs at 37 degrees C, and adhesion was measured by light microscopy. Compared with vehicle control, monocyte adhesion was increased in the androgen-treated HUVECs in a dose-dependent manner (116+/-6% and 128+/-3% for DHT 40 and 400 nmol/L respectively; P<0.001). HF blocked this increase (P>/=0.3 compared with control). Surface expression of endothelial cell adhesion molecules was measured by ELISA and revealed an increased expression of vascular cell adhesion molecule-1 (VCAM-1) in the DHT-treated HUVECs (125+/-5% versus 100+/-4% in controls; P=0.002), an effect also antagonized by HF (P>/=0.3 compared with controls). Furthermore, the DHT-related increase in adhesion was completely blocked by coincubation with anti-VCAM-1 antibody. Comparable results were obtained in arterial endothelial cells and in endothelium stimulated with the cytokine tumor necrosis factor-alpha. Androgen exposure is associated with increased human monocyte adhesion to endothelial cells, a proatherogenic effect mediated at least in part by an increased endothelial cell-surface expression of VCAM-1.

  14. Fibronectin Modulates Cell Adhesion and Signaling to Promote Single Cell Migration of Highly Invasive Oral Squamous Cell Carcinoma

    PubMed Central

    Ramos, Grasieli de Oliveira; Bernardi, Lisiane; Lauxen, Isabel; Sant’Ana Filho, Manoel; Horwitz, Alan Rick; Lamers, Marcelo Lazzaron

    2016-01-01

    Cell migration is regulated by adhesion to the extracellular matrix (ECM) through integrins and activation of small RhoGTPases, such as RhoA and Rac1, resulting in changes to actomyosin organization. During invasion, epithelial-derived tumor cells switch from laminin-enriched basal membrane to collagen and fibronectin-enriched connective tissue. How this switch affects the tumor migration is still unclear. We tested the hypothesis that ECM dictates the invasiveness of Oral Squamous Cell Carcinoma (OSCC). We analyzed the migratory properties of two OSCC lines, a low invasive cell line with high e-cadherin levels (Linv/HE-cad) or a highly invasive cell line with low e-cadherin levels (Hinv/LE-cad), plated on different ECM components. Compared to laminin, fibronectin induced non-directional collective migration and decreased RhoA activity in Linv/HE-cad OSCC. For Hinv/LE-cad OSCC, fibronectin increased Rac1 activity and induced smaller adhesions, resulting in a fast single cell migration in both 2D and 3D environments. Consistent with these observations, human OSCC biopsies exhibited similar changes in cell-ECM adhesion distribution at the invasive front of the tumor, where cells encounter fibronectin. Our results indicate that ECM composition might induce a switch from collective to single cell migration according to tumor invasiveness due to changes in cell-ECM adhesion and the resulting signaling pathways that alter actomyosin organization. PMID:26978651

  15. Tailored polyelectrolyte thin film multilayers to modulate cell adhesion.

    PubMed

    Muzzio, Nicolás E; Pasquale, Miguel A; Moya, Sergio E; Azzaroni, Omar

    2017-08-29

    The layer-by-layer assembly of polyelectrolyte multilayers (PEMs) from natural or synthetic polyelectrolytes constitutes a very versatile and simple strategy to modify surfaces and modulate cell behavior. PEMs assembled from natural polyelectrolytes are very appealing for biological and medical applications due to their high biocompatibility. However, PEMs from natural polyelectrolytes display poor cell adhesion as they are soft materials with an elasticity modulus of a few kilopascal. In this report, the authors present results on the modulation of cell adhesion of different immortalized cell lines by PEMs. Two strategies are employed to vary cell adhesion: (1) a heterogeneous polyelectrolyte multilayer is assembled employing a rigid bottom block including a synthetic polyelectrolyte with a soft upper block of natural polyelectrolytes and (2) polyelectrolyte multilayers from natural polyelectrolytes are thermally annealed after assembly. The physicochemical characteristics of the PEMs change upon thermal treatment. Depending on the composition of the polyelectrolyte multilayer, cell adhesion may be enhanced or reduced. Based on the impact on PEM properties and cell adhesion caused by thermal annealing, a temperature gradient is applied to a PEM of poly-l-lysine/alginate to induce a spatial variation of PEM properties, resulting in a gradient in cell adhesion. The strategies shown here can be employed as simple alternatives to tailor PEM properties by means of fully biocompatible procedures.

  16. Amplified effect of surface charge on cell adhesion by nanostructures

    NASA Astrophysics Data System (ADS)

    Xu, Li-Ping; Meng, Jingxin; Zhang, Shuaitao; Ma, Xinlei; Wang, Shutao

    2016-06-01

    Nano-biointerfaces with varied surface charge can be readily fabricated by integrating a template-based process with maleimide-thiol coupling chemistry. Significantly, nanostructures are employed for amplifying the effect of surface charge on cell adhesion, as revealed by the cell-adhesion performance, cell morphology and corresponding cytoskeletal organization. This study may provide a promising strategy for developing new biomedical materials with tailored cell adhesion for tissue implantation and regeneration.Nano-biointerfaces with varied surface charge can be readily fabricated by integrating a template-based process with maleimide-thiol coupling chemistry. Significantly, nanostructures are employed for amplifying the effect of surface charge on cell adhesion, as revealed by the cell-adhesion performance, cell morphology and corresponding cytoskeletal organization. This study may provide a promising strategy for developing new biomedical materials with tailored cell adhesion for tissue implantation and regeneration. Electronic supplementary information (ESI) available: Experimental details, SEM, KFM AFM, chemical modification and characterization. See DOI: 10.1039/c6nr00649c

  17. TMIGD1 is a novel adhesion molecule that protects epithelial cells from oxidative cell injury.

    PubMed

    Arafa, Emad; Bondzie, Philip A; Rezazadeh, Kobra; Meyer, Rosana D; Hartsough, Edward; Henderson, Joel M; Schwartz, John H; Chitalia, Vipul; Rahimi, Nader

    2015-10-01

    Oxidative damage to renal tubular epithelial cells is a fundamental pathogenic mechanism implicated in both acute kidney injury and chronic kidney diseases. Because epithelial cell survival influences the outcome of acute kidney injury and chronic kidney diseases, identifying its molecular regulators could provide new insight into pathobiology and possible new therapeutic strategies for these diseases. We have identified transmembrane and immunoglobulin domain-containing 1 (TMIGD1) as a novel adhesion molecule, which is highly conserved in humans and other species. TMIGD1 is expressed in renal tubular epithelial cells and promotes cell survival. The extracellular domain of TMIGD1 contains two putative immunoglobulin domains and mediates self-dimerization. Our data suggest that TMIGD1 regulates transepithelial electric resistance and permeability of renal epithelial cells. TMIGD1 controls cell migration, cell morphology, and protects renal epithelial cells from oxidative- and nutrient-deprivation-induced cell injury. Hydrogen peroxide-induced oxidative cell injury downregulates TMIGD1 expression and targets it for ubiquitination. Moreover, TMIGD1 expression is significantly affected in both acute kidney injury and in deoxy-corticosterone acetate and sodium chloride (deoxy-corticosterone acetate salt)-induced chronic hypertensive kidney disease mouse models. Taken together, we have identified TMIGD1 as a novel cell adhesion molecule expressed in kidney epithelial cells that protects kidney epithelial cells from oxidative cell injury to promote cell survival.

  18. Micropatterned Multicolor Dynamically Adhesive Substrates to Control Cell Adhesion and Multicellular Organization

    PubMed Central

    2015-01-01

    We present a novel technique to examine cell–cell interactions and directed cell migration using micropatterned substrates of three distinct regions: an adhesive region, a nonadhesive region, and a dynamically adhesive region switched by addition of a soluble factor to the medium. Combining microcontact printing with avidin–biotin capture chemistry, we pattern nonadhesive regions of avidin that become adhesive through the capture of biotinylated fibronectin. Our strategy overcomes several limitations of current two-color dynamically adhesive substrates by incorporating a third, permanently nonadhesive region. Having three spatially and functionally distinct regions allows for the realization of more complex configurations of cellular cocultures as well as intricate interface geometries between two cell populations for diverse heterotypic cell–cell interaction studies. We can now achieve spatial control over the path and direction of migration in addition to temporal control of the onset of migration, enabling studies that better recapitulate coordinated multicellular migration and organization in vitro. We confirm that cellular behavior is unaltered on captured biotinylated fibronectin as compared to printed fibronectin by examining the cells’ ability to spread, form adhesions, and migrate. We demonstrate the versatility of this approach in studies of migration and cellular cocultures, and further highlight its utility by probing Notch–Delta juxtacrine signaling at a patterned interface. PMID:24401172

  19. Running with Neighbors: Coordinating Cell Migration and Cell-Cell Adhesion

    PubMed Central

    Collins, Caitlin; Nelson, W. James

    2015-01-01

    Coordinated movement of large groups of cells is required for many biological processes, such as gastrulation and wound healing. During collective cell migration, cell-cell and cell-extracellular matrix (ECM) adhesions must be integrated so that cells maintain strong interactions with neighboring cells and the underlying substratum. Initiation and maintenance of cadherin adhesions at cell-cell junctions and integrin-based cell-ECM adhesions require integration of mechanical cues, dynamic regulation of the actin cytoskeleton, and input from specific signaling cascades, including Rho family GTPases. Here, we summarize recent advances made in understanding the interplay between these pathways at cadherin- and integrin-based adhesions during collective cell migration and highlight outstanding questions that remain in the field. PMID:26201843

  20. Running with neighbors: coordinating cell migration and cell-cell adhesion.

    PubMed

    Collins, Caitlin; Nelson, W James

    2015-10-01

    Coordinated movement of large groups of cells is required for many biological processes, such as gastrulation and wound healing. During collective cell migration, cell-cell and cell-extracellular matrix (ECM) adhesions must be integrated so that cells maintain strong interactions with neighboring cells and the underlying substratum. Initiation and maintenance of cadherin adhesions at cell-cell junctions and integrin-based cell-ECM adhesions require integration of mechanical cues, dynamic regulation of the actin cytoskeleton, and input from specific signaling cascades, including Rho family GTPases. Here, we summarize recent advances made in understanding the interplay between these pathways at cadherin-based and integrin-based adhesions during collective cell migration and highlight outstanding questions that remain in the field. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Sphingosylphosphorylcholine inhibits macrophage adhesion to vascular smooth muscle cells.

    PubMed

    Wirrig, Christiane; McKean, Jenny S; Wilson, Heather M; Nixon, Graeme F

    2016-09-01

    Inflammation in de-endothelialised arteries contributes to the development of cardiovascular diseases. The process that initiates this inflammatory response is the adhesion of monocytes/macrophages to exposed vascular smooth muscle cells, typically stimulated by cytokines such as tumour necrosis factor-α (TNF). The aim of this study was to determine the effect of the sphingolipid sphingosylphosphorylcholine (SPC) on the interaction of monocytes/macrophages with vascular smooth muscle cells. Rat aortic smooth muscle cells and rat bone marrow-derived macrophages were co-cultured using an in vitro assay following incubation with sphingolipids to assess inter-cellular adhesion. We reveal that SPC inhibits the TNF-induced adhesion of macrophages to smooth muscle cells. This anti-adhesive effect was the result of SPC-induced changes to the smooth muscle cells (but not the macrophages) and was mediated, at least partly, via the sphingosine 1-phosphate receptor subtype 2. Lipid raft domains were also required. Although SPC did not alter expression or membrane distribution of the adhesion proteins intercellular adhesion molecule-1 and vascular cellular adhesion protein-1 in smooth muscle cells, SPC preincubation inhibited the TNF-induced increase in inducible nitric oxide synthase (NOS2) resulting in a subsequent decrease in nitric oxide production. Inhibiting NOS2 activation in smooth muscle cells led to a decrease in the adhesion of macrophages to smooth muscle cells. This study has therefore delineated a novel pathway which can inhibit the interaction between macrophages and vascular smooth muscle cells via SPC-induced repression of NOS2 expression. This mechanism could represent a potential drug target in vascular disease. Copyright © 2016. Published by Elsevier Inc.

  2. The role of adhesion strength in human mesenchymal stem cell osteoblastic differentiation on biodegradable polymers

    NASA Astrophysics Data System (ADS)

    Krizan, Sylva Jana

    Human mesenchymal stem cells (hMSC) are promising candidates for promoting bone growth on biodegradable polymer scaffolds however little is known about early hMSC-polymer interactions. Adhesion is highly dynamic and during adhesive reinforcement, numerous proteins form adhesion plaques linking the cell's cytoskeleton with the extracellular environment. These proteins are known to affect cellular function but their role in hMSC differentiation is less clear. Adhesion plaques are associated with adhesive force, still a detachment force of hMSC on polycaprolactone (PCL), poly-lactide-co-glycolide (PLGA) or alginate has never been described or shown to affect downstream function. We demonstrate that hMSC attached to PCL, PLGA and alginate exhibit different adhesion strengths (tau50) as determined by both fluid shear and spinning disk systems, with PLGA demonstrating the greatest tau 50. Elastic modulus and hydrophobicity were characterized for these surfaces and correlated positively with tau50 to an optimum. Attachment studies of hMSC showed that adhesion plateau timespans were independent of cell line and surface but both morphology and focal adhesion expression varied by polymer type. Differentiation studies of hMSC on PLGA and PCL showed a strong association between markers of differentiation (alkaline phosphatase activity and mineral content) and tau50 within polymer groups, but a poor relationship was found between tau50 and differentiation across polymer groups, suggesting that other polymer properties may be important for differentiation. Subsequently, we examined the role of focal adhesion kinase (FAK) and Rho-GTPase (RhoA) on hMSC adhesion and differentiation when plated onto PLGA. hMSC were retrovirally transduced with mutant constructs of FAK and RhoA cDNA. Alternatively, hMSC were treated with Rho-kinase inhibitor, Y27632. Both cells transduced with mutant RhoA or FAK constructs, or those treated with Y27632 displayed aberrant cell morphology and changes

  3. Minimal synthetic cells to study integrin-mediated adhesion.

    PubMed

    Frohnmayer, Johannes P; Brüggemann, Dorothea; Eberhard, Christian; Neubauer, Stefanie; Mollenhauer, Christine; Boehm, Heike; Kessler, Horst; Geiger, Benjamin; Spatz, Joachim P

    2015-10-12

    To shed light on cell-adhesion-related molecular pathways, synthetic cells offer the unique advantage of a well-controlled model system with reduced molecular complexity. Herein, we show that liposomes with the reconstituted platelet integrin αIIb β3 as the adhesion-mediating transmembrane protein are a functional minimal cell model for studying cellular adhesion mechanisms in a defined environment. The interaction of these synthetic cells with various extracellular matrix proteins was analyzed using a quartz crystal microbalance with dissipation monitoring. The data indicated that integrin was functionally incorporated into the lipid vesicles, thus enabling integrin-specific adhesion of the engineered liposomes to fibrinogen- and fibronectin-functionalized surfaces. Then, we were able to initiate the detachment of integrin liposomes from these surfaces in the presence of the peptide GRGDSP, a process that is even faster with our newly synthesized peptide mimetic SN529, which specifically inhibits the integrin αIIb β3 .

  4. Minimal Synthetic Cells to Study Integrin-Mediated Adhesion

    PubMed Central

    Frohnmayer, Johannes P; Brüggemann, Dorothea; Eberhard, Christian; Neubauer, Stefanie; Mollenhauer, Christine; Boehm, Heike; Kessler, Horst; Geiger, Benjamin; Spatz, Joachim P

    2015-01-01

    To shed light on cell-adhesion-related molecular pathways, synthetic cells offer the unique advantage of a well-controlled model system with reduced molecular complexity. Herein, we show that liposomes with the reconstituted platelet integrin αIIbβ3 as the adhesion-mediating transmembrane protein are a functional minimal cell model for studying cellular adhesion mechanisms in a defined environment. The interaction of these synthetic cells with various extracellular matrix proteins was analyzed using a quartz crystal microbalance with dissipation monitoring. The data indicated that integrin was functionally incorporated into the lipid vesicles, thus enabling integrin-specific adhesion of the engineered liposomes to fibrinogen- and fibronectin-functionalized surfaces. Then, we were able to initiate the detachment of integrin liposomes from these surfaces in the presence of the peptide GRGDSP, a process that is even faster with our newly synthesized peptide mimetic SN529, which specifically inhibits the integrin αIIbβ3. PMID:26257266

  5. In vitro adhesion of Escherichia coli to porcine small intestinal epithelial cells: pili as adhesive factors.

    PubMed Central

    Isaacson, R E; Fusco, P C; Brinton, C C; Moon, H W

    1978-01-01

    Escherichia coli strains with pili (K99 or 987P) known to facilitate intestinal colonization adhered in vitro to porcine intestinal epithelial cells. These strains adhered equally to both ileal and jejunal epithelial cells. A laboratory E. coli strain that has type 1 pili also adhered to porcine intestinal epithelial cells. When nonpiliated cells derived from 987P+, K99+, or type 1 pilus+ strains were used for in vitro adhesion assays, they failed to adhere. The attachment of piliated bacteria to epithelial cells was a saturable process that plateaued at 30 to 40 bacterial cells attached per epithelial cell. Competitive inhibition of bacterial cell attachment to epithelial cells with purified pili showed that only purified 987P competed against the 987P+ strain and only purified type 1 pili competed against the type 1 pilus+ strain. Competition between a K99+ strain and K99 was not consistently achieved. K99+, 987P+, and type 1 pilus+ bacteria could be prevented from adhering to epithelial cells by Fab fragments specific for K99, 987P, or type 1 pili, respectively. Fab fragments specific for non-K99 bacterial surface antigens did not inhibit adhesion of the K99+ strain. It is concluded that adhesion of E. coli to porcine intestinal epithelial cells in vitro is mediated by pili and that the epithelial cells used apparently had different receptors for different pili. PMID:357285

  6. In vitro adhesion of Escherichia coli to porcine small intestinal epithelial cells: pili as adhesive factors.

    PubMed

    Isaacson, R E; Fusco, P C; Brinton, C C; Moon, H W

    1978-08-01

    Escherichia coli strains with pili (K99 or 987P) known to facilitate intestinal colonization adhered in vitro to porcine intestinal epithelial cells. These strains adhered equally to both ileal and jejunal epithelial cells. A laboratory E. coli strain that has type 1 pili also adhered to porcine intestinal epithelial cells. When nonpiliated cells derived from 987P+, K99+, or type 1 pilus+ strains were used for in vitro adhesion assays, they failed to adhere. The attachment of piliated bacteria to epithelial cells was a saturable process that plateaued at 30 to 40 bacterial cells attached per epithelial cell. Competitive inhibition of bacterial cell attachment to epithelial cells with purified pili showed that only purified 987P competed against the 987P+ strain and only purified type 1 pili competed against the type 1 pilus+ strain. Competition between a K99+ strain and K99 was not consistently achieved. K99+, 987P+, and type 1 pilus+ bacteria could be prevented from adhering to epithelial cells by Fab fragments specific for K99, 987P, or type 1 pili, respectively. Fab fragments specific for non-K99 bacterial surface antigens did not inhibit adhesion of the K99+ strain. It is concluded that adhesion of E. coli to porcine intestinal epithelial cells in vitro is mediated by pili and that the epithelial cells used apparently had different receptors for different pili.

  7. Dystrophin Dp71 in PC12 cell adhesion

    PubMed Central

    Enríquez-Aragón, Jose Arturo; Cerna-Cortés, Joel; Bermúdez de León, Mario; García-Sierra, Francisco; González, Everardo; Mornet, Dominique; Cisneros, Bulmaro

    2005-01-01

    Previously, we reported that PC12 cells with decreased Dp71 expression (antisense-Dp71 cells) display deficient nerve-growth-factor-induced neurite outgrowth. In this study, we show that disturbed neurite outgrowth of antisense-Dp71 cells is accompanied by decreased adhesion activity on laminin, collagen and fibronectin. In wild-type cells, the immunostaining of Dp71 and _1-integrin overlaps in the basal area contacting the substrate, but staining of both proteins decrease in the antisense-Dp71 cells. Morphology of antisense-Dp71 cells at the electron microscopic level is characterized by the lack of filopodia, cellular projections involved in adhesion. Our findings suggest that Dp71 is required for the efficient PC12 cell attachment to b1-integrin-dependent substrata and that decreased adhesion activity of the anti-sense-Dp71 cells could determine their deficiency to extend neurites. PMID:15706226

  8. Modulation of cell adhesion complexes by surface protein patterns.

    PubMed

    Pesen, Devrim; Haviland, David B

    2009-03-01

    Cell adhesion is an important process in several biological phenomena. To investigate the formation and organization of focal adhesions, we developed a patterning approach based on electron beam lithography. Nanodots (radius <1230 nm) and nanorings (inner radius <320 nm) of fibronectin (FN) were patterned on a K-Casein background. Intracellular vinculin immunofluorescence mirrored the FN nanopatterns. Atomic force microscopy showed that FN nanodots and nanorings organize the immediate cytoskeleton into straight fibrils and diverging fibril bundles, respectively. Our results suggest that a minimum of approximately 40 FN molecules is required for a cell to form a focal adhesion.

  9. Investigation of adhesion and mechanical properties of human glioma cells by single cell force spectroscopy and atomic force microscopy.

    PubMed

    Andolfi, Laura; Bourkoula, Eugenia; Migliorini, Elisa; Palma, Anita; Pucer, Anja; Skrap, Miran; Scoles, Giacinto; Beltrami, Antonio Paolo; Cesselli, Daniela; Lazzarino, Marco

    2014-01-01

    Active cell migration and invasion is a peculiar feature of glioma that makes this tumor able to rapidly infiltrate into the surrounding brain tissue. In our recent work, we identified a novel class of glioma-associated-stem cells (defined as GASC for high-grade glioma--HG--and Gasc for low-grade glioma--LG) that, although not tumorigenic, act supporting the biological aggressiveness of glioma-initiating stem cells (defined as GSC for HG and Gsc for LG) favoring also their motility. Migrating cancer cells undergo considerable molecular and cellular changes by remodeling their cytoskeleton and cell interactions with surrounding environment. To get a better understanding about the role of the glioma-associated-stem cells in tumor progression, cell deformability and interactions between glioma-initiating stem cells and glioma-associated-stem cells were investigated. Adhesion of HG/LG-cancer cells on HG/LG-glioma-associated stem cells was studied by time-lapse microscopy, while cell deformability and cell-cell adhesion strengths were quantified by indentation measurements by atomic force microscopy and single cell force spectroscopy. Our results demonstrate that for both HG and LG glioma, cancer-initiating-stem cells are softer than glioma-associated-stem cells, in agreement with their neoplastic features. The adhesion strength of GSC on GASC appears to be significantly lower than that observed for Gsc on Gasc. Whereas, GSC spread and firmly adhere on Gasc with an adhesion strength increased as compared to that obtained on GASC. These findings highlight that the grade of glioma-associated-stem cells plays an important role in modulating cancer cell adhesion, which could affect glioma cell migration, invasion and thus cancer aggressiveness. Moreover this work provides evidence about the importance of investigating cell adhesion and elasticity for new developments in disease diagnostics and therapeutics.

  10. Investigation of Adhesion and Mechanical Properties of Human Glioma Cells by Single Cell Force Spectroscopy and Atomic Force Microscopy

    PubMed Central

    Andolfi, Laura; Bourkoula, Eugenia; Migliorini, Elisa; Palma, Anita; Pucer, Anja; Skrap, Miran; Scoles, Giacinto; Beltrami, Antonio Paolo; Cesselli, Daniela; Lazzarino, Marco

    2014-01-01

    Active cell migration and invasion is a peculiar feature of glioma that makes this tumor able to rapidly infiltrate into the surrounding brain tissue. In our recent work, we identified a novel class of glioma-associated-stem cells (defined as GASC for high-grade glioma -HG- and Gasc for low-grade glioma -LG-) that, although not tumorigenic, act supporting the biological aggressiveness of glioma-initiating stem cells (defined as GSC for HG and Gsc for LG) favoring also their motility. Migrating cancer cells undergo considerable molecular and cellular changes by remodeling their cytoskeleton and cell interactions with surrounding environment. To get a better understanding about the role of the glioma-associated-stem cells in tumor progression, cell deformability and interactions between glioma-initiating stem cells and glioma-associated-stem cells were investigated. Adhesion of HG/LG-cancer cells on HG/LG-glioma-associated stem cells was studied by time-lapse microscopy, while cell deformability and cell-cell adhesion strengths were quantified by indentation measurements by atomic force microscopy and single cell force spectroscopy. Our results demonstrate that for both HG and LG glioma, cancer-initiating-stem cells are softer than glioma-associated-stem cells, in agreement with their neoplastic features. The adhesion strength of GSC on GASC appears to be significantly lower than that observed for Gsc on Gasc. Whereas, GSC spread and firmly adhere on Gasc with an adhesion strength increased as compared to that obtained on GASC. These findings highlight that the grade of glioma-associated-stem cells plays an important role in modulating cancer cell adhesion, which could affect glioma cell migration, invasion and thus cancer aggressiveness. Moreover this work provides evidence about the importance of investigating cell adhesion and elasticity for new developments in disease diagnostics and therapeutics. PMID:25390644

  11. Shape and Dynamics of Adhesive Cells: Mechanical Response of Open Systems

    NASA Astrophysics Data System (ADS)

    Yang, Yuehua; Jiang, Hongyuan

    2017-05-01

    Cell adhesion is an essential biological process. However, previous theoretical and experimental studies ignore a key variable, the changes of cellular volume and pressure, during the dynamic adhesion process. Here, we treat cells as open systems and propose a theoretical framework to investigate how the exchange of water and ions with the environment affects the shape and dynamics of cells adhered between two adhesive surfaces. We show that adherent cells can be either stable (convex or concave) or unstable (spontaneous rupture or collapse) depending on the adhesion energy density, the cell size, the separation of two adhesive surfaces, and the stiffness of the flexible surface. Strikingly, we find that the unstable states vanish when cellular volume and pressure are constant. We further show that the detachments of convex and concave cells are very different. The mechanical response of adherent cells is mainly determined by the competition between the loading rate and the regulation of the cellular volume and pressure. Finally, we show that as an open system the detachment of adherent cells is also significantly influenced by the loading history. Thus, our findings reveal a major difference between living cells and nonliving materials.

  12. Dynamic adhesion of umbilical cord blood endothelial progenitor cells under laminar shear stress.

    PubMed

    Angelos, Mathew G; Brown, Melissa A; Satterwhite, Lisa L; Levering, Vrad W; Shaked, Natan T; Truskey, George A

    2010-12-01

    Late outgrowth endothelial progenitor cells (EPCs) represent a promising cell source for rapid reendothelialization of damaged vasculature after expansion ex vivo and injection into the bloodstream. We characterized the dynamic adhesion of umbilical-cord-blood-derived EPCs (CB-EPCs) to surfaces coated with fibronectin. CB-EPC solution density affected the number of adherent cells and larger cells preferentially adhered at lower cell densities. The number of adherent cells varied with shear stress, with the maximum number of adherent cells and the shear stress at maximum adhesion depending upon fluid viscosity. CB-EPCs underwent limited rolling, transiently tethering for short distances before firm arrest. Immediately before arrest, the instantaneous velocity decreased independent of shear stress. A dimensional analysis indicated that adhesion was a function of the net force on the cells, the ratio of cell diffusion to sliding speed, and molecular diffusivity. Adhesion was not limited by the settling rate and was highly specific to α(5)β(1) integrin. Total internal reflection fluorescence microscopy showed that CB-EPCs produced multiple contacts of α(5)β(1) with the surface and the contact area grew during the first 20 min of attachment. These results demonstrate that CB-EPC adhesion from blood can occur under physiological levels of shear stress.

  13. Why do receptor–ligand bonds in cell adhesion cluster into discrete focal-adhesion sites?

    SciTech Connect

    Gao, Zhiwen; Gao, Yanfei

    2016-05-14

    We report that cell adhesion often exhibits the clustering of the receptor–ligand bonds into discrete focal-adhesion sites near the contact edge, thus resembling a rosette shape or a contracting membrane anchored by a small number of peripheral forces. The ligands on the extracellular matrix are immobile, and the receptors in the cell plasma membrane consist of two types: high-affinity integrins (that bond to the substrate ligands and are immobile) and low-affinity integrins (that are mobile and not bonded to the ligands). Thus the adhesion energy density is proportional to the high-affinity integrin density. This paper provides a mechanistic explanation for the clustering/assembling of the receptor–ligand bonds from two main points: (1) the cellular contractile force leads to the density evolution of these two types of integrins, and results into a large high-affinity integrin density near the contact edge and (2) the front of a propagating crack into a decreasing toughness field will be unstable and wavy. From this fracture mechanics perspective, the chemomechanical equilibrium is reached when a small number of patches with large receptor–ligand bond density are anticipated to form at the cell periphery, as opposed to a uniform distribution of bonds on the entire interface. Finally, cohesive fracture simulations show that the de-adhesion force can be significantly enhanced by this nonuniform bond density field, but the de-adhesion force anisotropy due to the substrate elastic anisotropy is significantly reduced.

  14. The Extracellular Electrical Resistivity in Cell Adhesion

    PubMed Central

    Gleixner, Raimund; Fromherz, Peter

    2006-01-01

    The interaction of cells in a tissue depends on the nature of the extracellular matrix. The electrical properties of the narrow extracellular space are unknown. Here we consider cell adhesion mediated by extracellular matrix protein on a solid substrate as a model system. We culture human embryonic kidney (HEK293) cells on silica coated with fibronectin and determine the electrical resistivity in the cell-solid junction \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{\\rho}_{{\\mathrm{J}}}=r_{{\\mathrm{J}}}d_{{\\mathrm{J}}}\\end{equation*}\\end{document} by combining measurements of the sheet resistance \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}r_{{\\mathrm{J}}}\\end{equation*}\\end{document} and of the distance \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}d_{{\\mathrm{J}}}\\end{equation*}\\end{document} between membrane and substrate. The sheet resistance is obtained from phase fluorometry of the voltage-sensitive dye ANNINE-5 by alternating-current stimulation from the substrate. The distance is measured by fluorescence interference contrast microscopy. We change the resistivity of the bath in a range from \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}66\\hspace{.167em}{\\Omega}\\hspace{.167em

  15. Charge displacement by adhesion and spreading of a cell.

    PubMed

    Svetlicić, V; Ivosević, N; Kovac, S; Zutić, V

    2001-01-01

    The potentiostatic control of surface charge density and interfacial tension of an electrode immersed in an aqueous electrolyte solution offers a possibility for direct studies of non-specific interactions in cell adhesion. Unicellular marine alga, Dunaliella tertiolecta (Chlorophyceae) of micrometer size and flexible cell envelope was used as a model cell and 0.1 M NaCl as supporting electrolyte. The dropping mercury electrode acted as in situ adhesion sensor and the electrochemical technique of chronoamperometry allowed measurement of the spread cell-electrode interface area and the distance of the closest approach of a cell. The adhesion and spreading of a single cell at the mercury electrode causes a displacement of counter-ions from the electrical double layer over a broad range of the positive and negative surface charge densities (from +16.0 to -8.2 microC/cm2). The flow of compensating current reflects the dynamics of adhesive contact formation and subsequent spreading of a cell. The adhesion and spreading rates are enhanced by the hydrodynamic regime of electrode's growing fluid interface. The distance of the closest approach of an adherent cell is smaller or equal to the distance of the outer Helmholz plane within the electrical double layer, i.e. 0.3-0.5 nm. There is a clear evidence of cell rupture for the potentials of maximum attraction as the area of the contact interface exceeded up to 100 times the cross-section area of a free cell.

  16. Single-cell force spectroscopy of pili-mediated adhesion

    NASA Astrophysics Data System (ADS)

    Sullan, Ruby May A.; Beaussart, Audrey; Tripathi, Prachi; Derclaye, Sylvie; El-Kirat-Chatel, Sofiane; Li, James K.; Schneider, Yves-Jacques; Vanderleyden, Jos; Lebeer, Sarah; Dufrêne, Yves F.

    2013-12-01

    Although bacterial pili are known to mediate cell adhesion to a variety of substrates, the molecular interactions behind this process are poorly understood. We report the direct measurement of the forces guiding pili-mediated adhesion, focusing on the medically important probiotic bacterium Lactobacillus rhamnosus GG (LGG). Using non-invasive single-cell force spectroscopy (SCFS), we quantify the adhesion forces between individual bacteria and biotic (mucin, intestinal cells) or abiotic (hydrophobic monolayers) surfaces. On hydrophobic surfaces, bacterial pili strengthen adhesion through remarkable nanospring properties, which - presumably - enable the bacteria to resist high shear forces under physiological conditions. On mucin, nanosprings are more frequent and adhesion forces larger, reflecting the influence of specific pili-mucin bonds. Interestingly, these mechanical responses are no longer observed on human intestinal Caco-2 cells. Rather, force curves exhibit constant force plateaus with extended ruptures reflecting the extraction of membrane nanotethers. These single-cell analyses provide novel insights into the molecular mechanisms by which piliated bacteria colonize surfaces (nanosprings, nanotethers), and offer exciting avenues in nanomedicine for understanding and controlling the adhesion of microbial cells (probiotics, pathogens).

  17. Sodium chloride affects Listeria monocytogenes adhesion to polystyrene and stainless steel by regulating flagella expression.

    PubMed

    Caly, D; Takilt, D; Lebret, V; Tresse, O

    2009-12-01

    To study the adhesion capability of seven strains of Listeria monocytogenes to polystyrene and stainless steel surfaces after cultivation at various NaCl concentrations. Determination of growth limits indicated that all seven strains were able to grow in up to 11% NaCl in rain heart infusion and 3 g l(-1) yeast extract-glucose at 20 degrees C, but no growth was detected at 15% NaCl. Adhesion of L. monocytogenes was estimated after 4-h incubation at 20 degrees C in 96-well microtitre plates. Statistical results revealed no significant difference between adhesion to polystyrene and stainless steel although surface properties were different. Adhesion between 0% and 6% NaCl was not different, whereas adhesion at 11% NaCl was significantly lower. This discrepancy in adhesion was correlated with the down-regulation of flagella at 11% NaCl. Only high salinity levels, close to nongrowth conditions, repressed the expression of flagella, and consequently, decreased the adhesion capability of L. monocytogenes. Adhesion of L. monocytogenes to inert surfaces depends on environmental conditions that affect flagellum expression. High salinity concentrations would delay biofilm formation.

  18. Effects of SOX2 on Proliferation, Migration and Adhesion of Human Dental Pulp Stem Cells.

    PubMed

    Liu, Pengfei; Cai, Jinglei; Dong, Delu; Chen, Yaoyu; Liu, Xiaobo; Wang, Yi; Zhou, Yulai

    2015-01-01

    As a key factor for cell pluripotent and self-renewing phenotypes, SOX2 has attracted scientists' attention gradually in recent years. However, its exact effects in dental pulp stem cells (DPSCs) are still unclear. In this study, we mainly investigated whether SOX2 could affect some biological functions of DPSCs. DPSCs were isolated from the dental pulp of human impacted third molar. SOX2 overexpressing DPSCs (DPSCs-SOX2) were established through retroviral infection. The effect of SOX2 on cell proliferation, migration and adhesion ability was evaluated with CCK-8, trans-well system and fibronectin-induced cell attachment experiment respectively. Whole genome expression of DPSCs-SOX2 was analyzed with RNA microarray. Furthermore, a rescue experiment was performed with SOX2-siRNA in DPSC-SOX2 to confirm the effect of SOX2 overexpression in DPSCs. We found that SOX2 overexpression could result in the enhancement of cell proliferation, migration, and adhesion in DPSCs obviously. RNA microarray analysis indicated that some key genes in the signal pathways associated with cell cycle, migration and adhesion were upregulated in different degree, and the results were further confirmed with qPCR and western-blot. Finally, DPSC-SOX2 transfected with SOX2-siRNA showed a decrease of cell proliferation, migration and adhesion ability, which further confirmed the biological effect of SOX2 in human DPSCs. This study indicated that SOX2 could improve the cell proliferation, migration and adhesion ability of DPSCs through regulating gene expression about cell cycle, migration and adhesion, and provided a novel strategy to develop seed cells with strong proliferation, migration and adhesion ability for tissue engineering.

  19. Quantifying Cell Adhesion through Impingement of a Controlled Microjet

    PubMed Central

    Visser, Claas Willem; Gielen, Marise V.; Hao, Zhenxia; Le Gac, Séverine; Lohse, Detlef; Sun, Chao

    2015-01-01

    The impingement of a submerged, liquid jet onto a cell-covered surface allows assessing cell attachment on surfaces in a straightforward and quantitative manner and in real time, yielding valuable information on cell adhesion. However, this approach is insufficiently characterized for reliable and routine use. In this work, we both model and measure the shear stress exerted by the jet on the impingement surface in the micrometer-domain, and subsequently correlate this to jet-induced cell detachment. The measured and numerically calculated shear stress data are in good agreement with each other, and with previously published values. Real-time monitoring of the cell detachment reveals the creation of a circular cell-free area upon jet impingement, with two successive detachment regimes: 1), a dynamic regime, during which the cell-free area grows as a function of both the maximum shear stress exerted by the jet and the jet diameter; followed by 2), a stationary regime, with no further evolution of the cell-free area. For the latter regime, which is relevant for cell adhesion strength assessment, a relationship between the jet Reynolds number, the cell-free area, and the cell adhesion strength is proposed. To illustrate the capability of the technique, the adhesion strength of HeLa cervical cancer cells is determined ((34 ± 14) N/m2). Real-time visualization of cell detachment in the dynamic regime shows that cells detach either cell-by-cell or by collectively (for which intact parts of the monolayer detach as cell sheets). This process is dictated by the cell monolayer density, with a typical threshold of (1.8 ± 0.2) × 109 cells/m2, above which the collective behavior is mostly observed. The jet impingement method presents great promises for the field of tissue engineering, as the influence of both the shear stress and the surface characteristics on cell adhesion can be systematically studied. PMID:25564849

  20. Cell adhesion molecules and in vitro fertilization.

    PubMed

    Simopoulou, Maria; Nikolopoulou, Elena; Dimakakos, Andreas; Charalabopoulos, Konstantinos; Koutsilieris, Michael

    2014-01-01

    This review addresses issues regarding the need in the in vitro fertilization (IVF) field for further predictive markers enhancing the standing embryo selection criteria. It aims to serve as a source of defining information for an audience interested in factors related to the wide range of multiple roles played by cell adhesion molecules (CAMs) in several aspects of IVF ultimately associated with the success of an IVF cycle. We begin by stressing the importance of enriching the standing embryo selection criteria available aiming for the golden standard: "extract as much information as possible focusing on non-invasive techniques" so as to guide us towards selecting the embryo with the highest implantation potential. We briefly describe the latest trends on how to best select the right embryo, moving closer towards elective single embryo transfer. These trends are: frozen embryo transfer for all, preimplantation genetic screening, non-invasive selection criteria, and time-lapse imaging. The main part of this review is dedicated to categorizing and presenting published research studies focused on the involvement of CAMs in IVF and its final outcome. Specifically, we discuss the association of CAMs with conditions and complications that arise from performing assisted reproductive techniques, such as ovarian hyperstimulation syndrome, the state of the endometrium, and tubal pregnancies, as well as the levels of CAMs in biological materials available in the IVF laboratory such as follicular fluid, trophectoderm, ovarian granulosa cells, oocytes, and embryos. To conclude, since CAMs have been successfully employed as a diagnostic tool in several pathologies in routine clinical work, we suggest that their multi-faceted nature could serve as a prognostic marker in assisted reproduction, aiming to enrich the list of non-invasive selection and predictive criteria in the IVF setting. We propose that in light of the well-documented involvement of CAMs in the developmental

  1. Adhesion and growth of dental pulp stem cells on enamel-like fluorapatite surfaces.

    PubMed

    Liu, J; Jin, T C; Chang, S; Czajka-Jakubowska, A; Clarkson, B H

    2011-03-01

    To study how apatite crystal alignment of an enamel-like substrate affects DPSC cellular adhesion and growth as a precursor to produce an in vitro enamel/dentin superstructure for future studies. The cells were subcultured in 10% FBS DMEM up to seven weeks on the two surfaces. Specimens were observed under SEM, counted, and analyzed using the human pathway-focused matrix and adhesion PCR array. After three days, the cell number on ordered FA surface was significantly higher than on the disordered surface. Of the 84 focused pathway genes, a total of 20 genes were either up or down regulated in the cells on ordered FA surface compared to the disordered surface. More interestingly, of the cell-matrix adhesion molecules, integrin alpha 7 and 8 (ITGA 7 and 8), integrin beta 3 and 4 (ITGB3 and 4), and the vitronectin receptor-integrin alpha V (ITGAV) and the key adhesion protein-fibronectin1 (FN1) were up-regulated. In SEM, both surfaces showed good biocompatibility and supported long term growth of DPSC cells but with functional cell-matrix interaction on the ordered FA surfaces. The enhanced cellular response of DPSC cell to the ordered FA crystal surface involves a set of delicately regulated matrix and adhesion molecules which could be manipulated by treating the cells with a dentin extract, to produce a dentin/enamel superstructure. Copyright © 2010 Wiley Periodicals, Inc.

  2. The right motifs for plant cell adhesion: what makes an adhesive site?

    PubMed

    Langhans, Markus; Weber, Wadim; Babel, Laura; Grunewald, Miriam; Meckel, Tobias

    2017-01-01

    Cells of multicellular organisms are surrounded by and attached to a matrix of fibrous polysaccharides and proteins known as the extracellular matrix. This fibrous network not only serves as a structural support to cells and tissues but also plays an integral part in the process as important as proliferation, differentiation, or defense. While at first sight, the extracellular matrices of plant and animals do not have much in common, a closer look reveals remarkable similarities. In particular, the proteins involved in the adhesion of the cell to the extracellular matrix share many functional properties. At the sequence level, however, a surprising lack of homology is found between adhesion-related proteins of plants and animals. Both protein machineries only reveal similarities between small subdomains and motifs, which further underlines their functional relationship. In this review, we provide an overview on the similarities between motifs in proteins known to be located at the plant cell wall-plasma membrane-cytoskeleton interface to proteins of the animal adhesome. We also show that by comparing the proteome of both adhesion machineries at the level of motifs, we are also able to identify potentially new candidate proteins that functionally contribute to the adhesion of the plant plasma membrane to the cell wall.

  3. Both mTORC1 and mTORC2 are involved in the regulation of cell adhesion

    PubMed Central

    Chen, Long; Xu, Baoshan; Liu, Lei; Liu, Chunxiao; Luo, Yan; Chen, Xin; Barzegar, Mansoureh; Chung, Jun; Huang, Shile

    2015-01-01

    mTOR is a central controller for cell growth/proliferation and survival. Recent studies have shown that mTOR also regulates cell adhesion, yet the underlying mechanism is not known. Here we found that inhibition of mTOR by rapamycin reduced the basal or type I insulin-like growth factor (IGF-1)-stimulated adhesion of cancer cells. Further research revealed that both mTORC1 and mTORC2 were involved in the regulation of cell adhesion, as silencing expression of raptor or rictor inhibited cell adhesion. Also, PP242, an mTORC1/2 kinase inhibitor, inhibited cell adhesion more potently than rapamycin (mTORC1 inhibitor). Of interest, ectopic expression of constitutively active and rapamycin-resistant mutant of p70 kinase 1 (S6K1) or downregulation of eukaryotic initiation factor 4E (eIF4E)-binding protein 1 (4E-BP1) conferred resistance to rapamycin inhibition of cell adhesion, whereas expression of constitutively hypophosphorylated 4E-BP1 (4EBP1-5A) or downregulation of S6K1 suppressed cell adhesion. In contrast, neither genetic manipulation of Akt activity nor pharmacological inhibition of Akt affected cell adhesion. The results suggest that both mTORC1 and mTORC2 are involved in the regulation of cell adhesion; and mTORC1 regulates cell adhesion through S6K1 and 4E-BP1 pathways, but mTORC2 regulates cell adhesion via Akt-independent mechanism. PMID:25762619

  4. Inhibition of cell adhesion by phosphorylated Ezrin/Radixin/Moesin.

    PubMed

    Tachibana, Kouichi; Haghparast, Seyed Mohammad Ali; Miyake, Jun

    2015-01-01

    Altered phosphorylation status of the C-terminal Thr residues of Ezrin/Radixin/Moesin (ERM) is often linked to cell shape change. To determine the role of phophorylated ERM, we modified phosphorylation status of ERM and investigated changes in cell adhesion and morphology. Treatment with Calyculin-A (Cal-A), a protein phosphatase inhibitor, dramatically augmented phosphorylated ERM (phospho-ERM). Cal-A-treatment or expression of phospho-mimetic Moesin mutant (Moesin-TD) induced cell rounding in adherent cells. Moreover, reattachment of detached cells to substrate was inhibited by either treatment. Phospho-ERM, Moesin-TD and actin cytoskeleton were observed at the plasma membrane of such round cells. Augmented cell surface rigidity was also observed in both cases. Meanwhile, non-adherent KG-1 cells were rather rich in phospho-ERM. Treatment with Staurosporine, a protein kinase inhibitor that dephosphorylates phospho-ERM, up-regulated the integrin-dependent adhesion of KG-1 cells to substrate. These findings strongly suggest the followings: (1) Phospho-ERM inhibit cell adhesion, and therefore, dephosphorylation of ERM proteins is essential for cell adhesion. (2) Phospho-ERM induce formation and/or maintenance of spherical cell shape. (3) ERM are constitutively both phosphorylated and dephosphorylated in cultured adherent and non-adherent cells.

  5. Adhesion and migration of cells responding to microtopography.

    PubMed

    Estévez, Maruxa; Martínez, Elena; Yarwood, Stephen J; Dalby, Matthew J; Samitier, Josep

    2015-05-01

    It is known that cells respond strongly to microtopography. However, cellular mechanisms of response are unclear. Here, we study wild-type fibroblasts responding to 25 µm(2) posts and compare their response to that of FAK(-/-) fibroblasts and fibroblasts with PMA treatment to stimulate protein kinase C (PKC) and the small g-protein Rac. FAK knockout cells modulated adhesion number and size in a similar way to cells on topography; that is, they used more, smaller adhesions, but migration was almost completely stalled demonstrating the importance of FAK signaling in contact guidance and adhesion turnover. Little similarity, however, was observed to PKC stimulated cells and cells on the topography. Interestingly, with PKC stimulation the cell nuclei became highly deformable bringing focus on these surfaces to the study of metastasis. Surfaces that aid the study of cellular migration are important in developing understanding of mechanisms of wound healing and repair in aligned tissues such as ligament and tendon.

  6. Cell adhesion in zebrafish embryos is modulated by March 8.

    PubMed

    Kim, Mi Ha; Rebbert, Martha L; Ro, Hyunju; Won, Minho; Dawid, Igor B

    2014-01-01

    March 8 is a member of a family of transmembrane E3 ubiquitin ligases that have been studied mostly for their role in the immune system. We find that March 8 is expressed in the zebrafish egg and early embryo, suggesting a role in development. Both knock-down and overexpression of March 8 leads to abnormal development. The phenotype of zebrafish embryos and Xenopus animal explants overexpressing March 8 implicates impairment of cell adhesion as a cause of the effect. In zebrafish embryos and in cultured cells, overexpression of March 8 leads to a reduction in the surface levels of E-cadherin, a major cell-cell adhesion molecule. Experiments in cell culture further show that E-cadherin can be ubiquitinated by March 8. On the basis of these observations we suggest that March 8 functions in the embryo to modulate the strength of cell adhesion by regulating the localization of E-cadherin.

  7. Filamin A protects cells against force-induced apoptosis by stabilizing talin- and vinculin-containing cell adhesions.

    PubMed

    Pinto, Vanessa I; Senini, Vincent W; Wang, Yongqiang; Kazembe, Mwayi P; McCulloch, Christopher A

    2014-01-01

    In mechanically loaded tissues such as weight-bearing joints, myocardium, and periodontal ligament, pathophysiological forces can disrupt cell-matrix contacts, which can induce cell death, leading to tissue and organ dysfunction. Protection against force-induced cell death may be mediated by filamin A (FLNa), an actin-binding protein that regulates β1 integrin-mediated cell adhesion. We examined the affect of filamin expression on collagen distribution and cell death in the periodontal ligament, a force-loaded tissue. Conditional deletion of FLNa in fibroblasts was associated with 2-fold increase of acellular areas in periodontal ligament and 7-fold higher proportions of apoptotic cells. In cultured fibroblasts with FLNa knockdown, we examined the affect of supraphysiological forces (1 pN/μm(2) cell area; applied through the β1 integrin) on recruitment of talin and vinculin to focal adhesions and on apoptosis. Compared with the wild type, FLNa-knockdown cells exhibited 3-fold increases in floating cells after overnight force application and a 2-fold increase in cell detachment. Force induced time-dependent reductions (P<0.05) in the numbers of activated β1 integrin-, talin-, and vinculin-stained adhesions in FLNa-knockdown compared with those in wild-type cells. We conclude that FLNa protects against apoptosis in force-loaded cells, and this protection is mediated by enhanced formation and maturation of matrix adhesions.

  8. Therapeutic effects of tyroservatide on metastasis of lung cancer and its mechanism affecting integrin-focal adhesion kinase signal transduction.

    PubMed

    Huang, Yu-ting; Zhao, Lan; Fu, Zheng; Zhao, Meng; Song, Xiao-meng; Jia, Jing; Wang, Song; Li, Jin-ping; Zhu, Zhi-feng; Lin, Gang; Lu, Rong; Yao, Zhi

    2016-01-01

    Tyroservatide (YSV) can inhibit the growth and metastasis of mouse lung cancer significantly. This study investigated the therapeutic effects of tripeptide YSV on metastasis of human lung cancer cells and explored its possible mechanism that affects integrin-focal adhesion kinase (FAK) signal transduction in tumor cells. YSV significantly inhibited the adhesion and the invasion of highly metastatic human lung cancer cell lines 95D, A549, and NCI-H1299. In addition, YSV significantly inhibited phosphorylation of FAK Tyr397 and FAK Tyr576/577 in the 95D, A549, and NCI-H1299 human lung cancer cells in vitro. And the mRNA level and protein expression of FAK in these human lung cancer cells decreased at the same time. YSV also significantly inhibited mRNA and protein levels of integrin β1 and integrin β3 in the 95D, A549, and NCI-H1299 human lung cancer cells. Our research showed that YSV inhibited adhesion and invasion of human lung cancer cells and exhibited therapeutic effects on metastasis of lung cancer.

  9. Mitogen-activated protein kinase modulates ethanol inhibition of cell adhesion mediated by the L1 neural cell adhesion molecule

    PubMed Central

    Dou, Xiaowei; Wilkemeyer, Michael F.; Menkari, Carrie E.; Parnell, Scott E.; Sulik, Kathleen K.; Charness, Michael E.

    2013-01-01

    There is a genetic contribution to fetal alcohol spectrum disorders (FASD), but the identification of candidate genes has been elusive. Ethanol may cause FASD in part by decreasing the adhesion of the developmentally critical L1 cell adhesion molecule through interactions with an alcohol binding pocket on the extracellular domain. Pharmacologic inhibition or genetic knockdown of ERK2 did not alter L1 adhesion, but markedly decreased ethanol inhibition of L1 adhesion in NIH/3T3 cells and NG108-15 cells. Likewise, leucine replacement of S1248, an ERK2 substrate on the L1 cytoplasmic domain, did not decrease L1 adhesion, but abolished ethanol inhibition of L1 adhesion. Stable transfection of NIH/3T3 cells with human L1 resulted in clonal cell lines in which L1 adhesion was consistently sensitive or insensitive to ethanol for more than a decade. ERK2 activity and S1248 phosphorylation were greater in ethanol-sensitive NIH/3T3 clonal cell lines than in their ethanol-insensitive counterparts. Ethanol-insensitive cells became ethanol sensitive after increasing ERK2 activity by transfection with a constitutively active MAP kinase kinase 1. Finally, embryos from two substrains of C57BL mice that differ in susceptibility to ethanol teratogenesis showed corresponding differences in MAPK activity. Our data suggest that ERK2 phosphorylation of S1248 modulates ethanol inhibition of L1 adhesion by inside-out signaling and that differential regulation of ERK2 signaling might contribute to genetic susceptibility to FASD. Moreover, identification of a specific locus that regulates ethanol sensitivity, but not L1 function, might facilitate the rational design of drugs that block ethanol neurotoxicity. PMID:23431142

  10. Functionalization of CoCr surfaces with cell adhesive peptides to promote HUVECs adhesion and proliferation

    NASA Astrophysics Data System (ADS)

    Castellanos, Maria Isabel; Mas-Moruno, Carlos; Grau, Anna; Serra-Picamal, Xavier; Trepat, Xavier; Albericio, Fernando; Joner, Michael; Gil, Francisco Javier; Ginebra, Maria Pau; Manero, Jose María; Pegueroles, Marta

    2017-01-01

    Biomimetic surface modification with peptides that have specific cell-binding moieties is a promising approach to improve endothelialization of metal-based stents. In this study, we functionalized CoCr surfaces with RGDS, REDV, YIGSR peptides and their combinations to promote endothelial cells (ECs) adhesion and proliferation. An extensive characterization of the functionalized surfaces was performed by XPS analysis, surface charge and quartz crystal microbalance with dissipation monitoring (QCM-D), which demonstrated the successful immobilization of the peptides to the surface. Cell studies demonstrated that the covalent functionalization of CoCr surfaces with an equimolar combination of RGDS and YIGSR represents the most powerful strategy to enhance the early stages of ECs adhesion and proliferation, indicating a positive synergistic effect between the two peptide motifs. Although these peptide sequences slightly increased smooth muscle cells (SMCs) adhesion, these values were ten times lower than those observed for ECs. The combination of RGDS with the REDV sequence did not show synergistic effects in promoting the adhesion or proliferation of ECs. The strategy presented in this study holds great potential to overcome clinical limitations of current metal stents by enhancing their capacity to support surface endothelialization.

  11. The effects of cell adhesion on the growth and protein productivity of animal cells.

    PubMed

    Nishijima, K; Fujiki, T; Kojima, H; Iijima, S

    2000-07-01

    We investigated the effect of cell adhesion on cellgrowth and productivity of recombinant protein inChinese hamster ovary (CHO) cells. Cells cultured innormal tissue culture dishes attached to the dishsurfaces and grew as a monolayer, while cells culturedin non-treated dishes proliferated in suspension assingle cells without adhering to the dish surfaces. On an agarose-coated dish surface, cell aggregatesformed without attaching to the dish. Growth rates inboth suspension cultures were slightly lower thanthose in monolayer culture. Cell cycle analysisindicated that the duration of the G(1) phase insuspension cultures was longer than that in monolayerculture, suggesting that attachment to the substratummainly affected the transition from the G(1) to theS phase. Consistent with this, CDK inhibitor p27,that inhibits the G(1)S transition, was induced inthe cells cultured in suspension.To assess the productivity of recombinant proteins,CHO cells were transfected with a plasmid containingmurine interferon gamma (mIFN-gamma) under thecontrol of the cytomegalovirus promoter. Insuspension culture, mIFN-gamma productivity wasslightly lower than that in the monolayer culture. When protein kinase C was activated by phorbol ester,mIFN-gamma production was enhanced in both themonolayer and suspension cultures. However, theproductivity in the suspension culture was lower thanthat in the adherent culture even in the presence ofhigh concentrations of phorbol ester. These resultssuggested that cell adhesion to the substratum affectsvarious features of CHO cells.

  12. Cell-cell and cell-ECM adhesions cooperate to organize actomyosin networks and maintain force transmission during Dorsal Closure.

    PubMed

    Goodwin, Katharine; Lostchuck, Emily E; Cramb, Kaitlyn M L; Zulueta-Coarasa, Teresa; Fernandez-Gonzalez, Rodrigo; Tanentzapf, Guy

    2017-03-22

    Tissue morphogenesis relies on the coordinated action of actin networks, cell-cell adhesions, and cell-ECM adhesions. Such coordination can be achieved through crosstalk between cell-cell and cell-ECM adhesions. Drosophila Dorsal Closure (DC), a morphogenetic process wherein an extra-embryonic tissue called the amnioserosa contracts and ingresses to close a discontinuity in the dorsal epidermis of the embryo, requires both cell-cell and cell-ECM adhesions. However, whether the function of these two types of adhesion is coordinated during DC is not known. Here, we analyzed possible interdependence between cell-cell and cell-ECM adhesions during DC, and its effect on the actomyosin network. We find that loss of cell-ECM adhesion results in aberrant distributions of cadherin-mediated adhesions and actin networks in the amnioserosa; and subsequent disruption of myosin recruitment and dynamics. Moreover, loss of cell-cell adhesion caused an upregulation of cell-ECM adhesion, leading to reduced cell deformation and force transmission across amnioserosa cells. Our results show how interdependence between cell-cell and cell-ECM adhesions is important in regulating cell behaviours, force generation and force transmission critical for tissue morphogenesis.

  13. Effect of sterilization and water rinsing on cell adhesion to titanium surfaces

    NASA Astrophysics Data System (ADS)

    Hirano, Mitsuhiro; Kozuka, Taro; Asano, Yuta; Kakuchi, Yuko; Arai, Hirofumi; Ohtsu, Naofumi

    2014-08-01

    In this study, the effects of sterilization and water rinsing on cell adhesion to titanium (Ti) surfaces were investigated. Ti substrates were treated using autoclave, dry-heating, and 70% ethanol. Thereafter, some of the substrates were rinsed with sterilized ultrapure water. Osteoblast-like MC3T3-E1 cells were seeded on the Ti surfaces and the numbers of adhered cells were counted after cultivation for 24 h. The number of cells adhered to ethanol-treated plates was lower than that on autoclave- and dry-heat-sterilized Ti substrates. However, interestingly, the cell adhesion performance on the ethanol-treated substrates was superior compared to that of the other substrates, after rinsing with ultrapure water. To investigate the origin of these differences, the chemical state of the treated surfaces was analyzed by X-ray photoelectron spectroscopy. We found a clear correlation between the number of adhered cells and the concentration of hydroxide groups (OH-) on the surface, thus indicating that a change in OH- concentration affects the cell adhesion performance on Ti substrates. Since the sterilization and subsequent water rinsing affect the cell adhesion on Ti substrates, we suggest that the sterilization methods should be unified to correctly evaluate the cytocompatibility of metallic materials.

  14. Quantification of Depletion-Induced Adhesion of Red Blood Cells

    NASA Astrophysics Data System (ADS)

    Steffen, P.; Verdier, C.; Wagner, C.

    2013-01-01

    Red blood cells (RBCs) are known to form aggregates in the form of rouleaux due to the presence of plasma proteins under physiological conditions. The formation of rouleaux can also be induced in vitro by the addition of macromolecules to the RBC suspension. Current data on the adhesion strength between red blood cells in their natural discocyte shapes mostly originate from indirect measurements such as flow chamber experiments, but data is lacking at the single cell level. Here, we present measurements on the dextran-induced aggregation of red blood cells using atomic force microscopy-based single cell force spectroscopy. The effects of dextran concentration and molecular weight on the interaction energy of adhering RBCs were determined. The results on adhesion energy are in excellent agreement with a model based on the depletion effect and previous experimental studies. Furthermore, our method allowed to determine the adhesion force, a quantity that is needed in theoretical investigations on blood flow.

  15. Thinking outside the cell: how cadherins drive adhesion

    PubMed Central

    Brasch, Julia; Harrison, Oliver J.; Honig, Barry; Shapiro, Lawrence

    2012-01-01

    Cadherins embody a superfamily of cell-surface glycoproteins whose ectodomains contain multiple repeats of β-sandwich EC (extracellular cadherin) domains that adopt a similar fold to immunoglobulin domains. The best characterized cadherins are the vertebrate “classical” cadherins, which mediate adhesion via trans homodimerization between their membrane-distal EC1 domains that extend from apposed cells, and assemble intercellular adherens junctions through cis clustering. To form mature trans adhesive dimers, cadherin domains from apposed cells dimerize in a “strand-swapped” conformation. This occurs in a two-step binding process involving a fast-binding intermediate called the “X-dimer”. Trans dimers are less flexible than cadherin monomers, a factor which drives junction assembly following cell-cell contact by reducing the entropic cost associated with the formation of lateral cis oligomers. Cadherins outside of the classical subfamily appear to have evolved distinct adhesive mechanisms which are just now beginning to be understood. PMID:22555008

  16. Quantification of depletion-induced adhesion of red blood cells.

    PubMed

    Steffen, P; Verdier, C; Wagner, C

    2013-01-04

    Red blood cells (RBCs) are known to form aggregates in the form of rouleaux due to the presence of plasma proteins under physiological conditions. The formation of rouleaux can also be induced in vitro by the addition of macromolecules to the RBC suspension. Current data on the adhesion strength between red blood cells in their natural discocyte shapes mostly originate from indirect measurements such as flow chamber experiments, but data is lacking at the single cell level. Here, we present measurements on the dextran-induced aggregation of red blood cells using atomic force microscopy-based single cell force spectroscopy. The effects of dextran concentration and molecular weight on the interaction energy of adhering RBCs were determined. The results on adhesion energy are in excellent agreement with a model based on the depletion effect and previous experimental studies. Furthermore, our method allowed to determine the adhesion force, a quantity that is needed in theoretical investigations on blood flow.

  17. Thinking outside the cell: how cadherins drive adhesion.

    PubMed

    Brasch, Julia; Harrison, Oliver J; Honig, Barry; Shapiro, Lawrence

    2012-06-01

    Cadherins are a superfamily of cell surface glycoproteins whose ectodomains contain multiple repeats of β-sandwich extracellular cadherin (EC) domains that adopt a similar fold to immunoglobulin domains. The best characterized cadherins are the vertebrate 'classical' cadherins, which mediate adhesion via trans homodimerization between their membrane-distal EC1 domains that extend from apposed cells, and assemble intercellular adherens junctions through cis clustering. To form mature trans adhesive dimers, cadherin domains from apposed cells dimerize in a 'strand-swapped' conformation. This occurs in a two-step binding process involving a fast-binding intermediate called the 'X-dimer'. Trans dimers are less flexible than cadherin monomers, a factor that drives junction assembly following cell-cell contact by reducing the entropic cost associated with the formation of lateral cis oligomers. Cadherins outside the classical subfamily appear to have evolved distinct adhesive mechanisms that are only now beginning to be understood.

  18. Non-Cell-Adhesive Substrates for Printing of Arrayed Biomaterials

    PubMed Central

    Appel, Eric A.; Larson, Benjamin L.; Luly, Kathryn M.; Kim, Jinseong D.

    2015-01-01

    Cellular microarrays have become extremely useful in expediting the investigation of large libraries of (bio)materials for both in vitro and in vivo biomedical applications. We have developed an exceedingly simple strategy for the fabrication of non-cell-adhesive substrates supporting the immobilization of diverse (bio)material features, including both monomeric and polymeric adhesion molecules (e.g. RGD and polylysine), hydrogels, and polymers. PMID:25430948

  19. Rocking adhesion assay system to study adhesion and transendothelial migration of cancer cells.

    PubMed

    Bapu, Deepashree; Khadim, Munira; Brooks, Susan A

    2014-01-01

    Adhesion of metastatic cancer cells to the vascular endothelium of the target organs and their subsequent transendothelial migration is one of the critical, yet poorly understood, steps of the metastatic cascade. Conventionally, the mechanisms of this complex process have been studied using static adhesion systems or flow assay systems. Static assay systems are easy to set up and perform but do not mimic the physiological conditions of blood flow. Flow assays closely mimic physiological conditions of flow but are time consuming and require specialist equipment. In this chapter we describe the rocking adhesion system which incorporates the key advantages of both the static and flow assay systems and not only is easy to set up and perform but also mimics conditions of blood flow.

  20. Dynamic interplay between adhesion surfaces in carcinomas: Cell-cell and cell-matrix crosstalk

    PubMed Central

    Smith, Yvonne E; Vellanki, Sri HariKrishna; Hopkins, Ann M

    2016-01-01

    Cell-cell and cell-matrix signaling and communication between adhesion sites involve mechanisms which are required for cellular functions during normal development and homeostasis; however these cellular functions and mechanisms are often deregulated in cancer. Aberrant signaling at cell-cell and cell-matrix adhesion sites often involves downstream mediators including Rho GTPases and tyrosine kinases. This review discusses these molecules as putative mediators of cellular crosstalk between cell-cell and cell-matrix adhesion sites, in addition to their attractiveness as therapeutic targets in cancer. Interestingly, inter-junctional crosstalk mechanisms are frequently typified by the way in which bacterial and viral pathogens opportunistically infect or intoxicate mammalian cells. This review therefore also discusses the concept of learning from pathogen-host interaction studies to better understand coordinated communication between cell-cell and cell-matrix adhesion sites, in addition to highlighting the potential therapeutic usefulness of exploiting pathogens or their products to tap into inter-junctional crosstalk. Taken together, we feel that increased knowledge around mechanisms of cell-cell and cell-matrix adhesion site crosstalk and consequently a greater understanding of their therapeutic targeting offers a unique opportunity to contribute to the emerging molecular revolution in cancer biology. PMID:26981196

  1. Silencing GFAP isoforms in astrocytoma cells disturbs laminin-dependent motility and cell adhesion.

    PubMed

    Moeton, Martina; Kanski, Regina; Stassen, Oscar M J A; Sluijs, Jacqueline A; Geerts, Dirk; van Tijn, Paula; Wiche, Gerhard; van Strien, Miriam E; Hol, Elly M

    2014-07-01

    Glial fibrillary acidic protein (GFAP) is an intermediate filament protein expressed in astrocytes and neural stem cells. The GFAP gene is alternatively spliced, and expression of GFAP is highly regulated during development, on brain damage, and in neurodegenerative diseases. GFAPα is the canonical splice variant and is expressed in all GFAP-positive cells. In the human brain, the alternatively spliced transcript GFAPδ marks specialized astrocyte populations, such as subpial astrocytes and the neurogenic astrocytes in the human subventricular zone. We here show that shifting the GFAP isoform ratio in favor of GFAPδ in astrocytoma cells, by selectively silencing the canonical isoform GFAPα with short hairpin RNAs, induced a change in integrins, a decrease in plectin, and an increase in expression of the extracellular matrix component laminin. Together, this did not affect cell proliferation but resulted in a significantly decreased motility of astrocytoma cells. In contrast, a down-regulation of all GFAP isoforms led to less cell spreading, increased integrin expression, and a >100-fold difference in the adhesion of astrocytoma cells to laminin. In summary, isoform-specific silencing of GFAP revealed distinct roles of a specialized GFAP network in regulating the interaction of astrocytoma cells with the extracellular matrix through laminin.-Moeton, M., Kanski, R., Stassen, O. M. J. A., Sluijs, J. A., Geerts, D., van Tijn, P., Wiche, G., van Strien, M. E., Hol, E. M. Silencing GFAP isoforms in astrocytoma cells disturbs laminin dependent motility and cell adhesion. © FASEB.

  2. Arachidonic acid randomizes endothelial cell motion and regulates adhesion and migration.

    PubMed

    Rossen, Ninna Struck; Hansen, Anker Jon; Selhuber-Unkel, Christine; Oddershede, Lene Broeng

    2011-01-01

    Cell adhesion and migration are essential for the evolution, organization, and repair of living organisms. An example of a combination of these processes is the formation of new blood vessels (angiogenesis), which is mediated by a directed migration and adhesion of endothelial cells (ECs). Angiogenesis is an essential part of wound healing and a prerequisite of cancerous tumor growth. We investigated the effect of the amphiphilic compound arachidonic acid (AA) on EC adhesion and migration by combining live cell imaging with biophysical analysis methods. AA significantly influenced both EC adhesion and migration, in either a stimulating or inhibiting fashion depending on AA concentration. The temporal evolution of cell adhesion area was well described by a two-phase model. In the first phase, the spreading dynamics were independent of AA concentration. In the latter phase, the spreading dynamics increased at low AA concentrations and decreased at high AA concentrations. AA also affected EC migration; though the instantaneous speed of individual cells remained independent of AA concentration, the individual cells lost their sense of direction upon addition of AA, thus giving rise to an overall decrease in the collective motion of a confluent EC monolayer into vacant space. Addition of AA also caused ECs to become more elongated, this possibly being related to incorporation of AA in the EC membrane thus mediating a change in the viscosity of the membrane. Hence, AA is a promising non-receptor specific regulator of wound healing and angiogenesis.

  3. Finite element analysis of traction force microscopy: influence of cell mechanics, adhesion, and morphology.

    PubMed

    Zielinski, Rachel; Mihai, Cosmin; Kniss, Douglas; Ghadiali, Samir N

    2013-07-01

    The interactions between adherent cells and their extracellular matrix (ECM) have been shown to play an important role in many biological processes, such as wound healing, morphogenesis, differentiation, and cell migration. Cells attach to the ECM at focal adhesion sites and transmit contractile forces to the substrate via cytoskeletal actin stress fibers. This contraction results in traction stresses within the substrate/ECM. Traction force microscopy (TFM) is an experimental technique used to quantify the contractile forces generated by adherent cells. In TFM, cells are seeded on a flexible substrate and displacements of the substrate caused by cell contraction are tracked and converted to a traction stress field. The magnitude of these traction stresses are normally used as a surrogate measure of internal cell contractile force or contractility. We hypothesize that in addition to contractile force, other biomechanical properties including cell stiffness, adhesion energy density, and cell morphology may affect the traction stresses measured by TFM. In this study, we developed finite element models of the 2D and 3D TFM techniques to investigate how changes in several biomechanical properties alter the traction stresses measured by TFM. We independently varied cell stiffness, cell-ECM adhesion energy density, cell aspect ratio, and contractility and performed a sensitivity analysis to determine which parameters significantly contribute to the measured maximum traction stress and net contractile moment. Results suggest that changes in cell stiffness and adhesion energy density can significantly alter measured tractions, independent of contractility. Based on a sensitivity analysis, we developed a correction factor to account for changes in cell stiffness and adhesion and successfully applied this correction factor algorithm to experimental TFM measurements in invasive and noninvasive cancer cells. Therefore, application of these types of corrections to TFM

  4. Amphiphilic cationic peptides mediate cell adhesion to plastic surfaces.

    PubMed

    Rideout, D C; Lambert, M; Kendall, D A; Moe, G R; Osterman, D G; Tao, H P; Weinstein, I B; Kaiser, E T

    1985-09-01

    Four amphiphilic peptides, each with net charges of +2 or more at neutrality and molecular weights under 4 kilodaltons, were found to mediate the adhesion of normal rat kidney fibroblasts to polystyrene surfaces. Two of these peptides, a model for calcitonin (peptide 1, MCT) and melittin (peptide 2, MEL), form amphiphilic alpha-helical structures at aqueous/nonpolar interfaces. The other two, a luteinizing hormone-releasing hormone model (peptide 3, LHM) and a platelet factor model (peptide 4, MPF) form beta-strand structures in amphiphilic environments. Although it contains only 10 residues, LHM mediated adhesion to surfaces coated with solutions containing as little as 10 pmoles/ml of peptide. All four of these peptides were capable of forming monolayers at air-buffer interfaces with collapse pressures greater than 20 dynes/cm. None of these four peptides contains the tetrapeptide sequence Arg-Gly-Asp-Ser, which has been associated with fibronectin-mediated cell adhesion. Ten polypeptides that also lacked the sequence Arg-Gly-Asp-Ser but were nonamphiphilic and/or had net charges less than +2 at neutrality were all incapable of mediating cell adhesion (Pierschbacher and Ruoslahti, 1984). The morphologies of NRK cells spread on polystyrene coated with peptide LHM resemble the morphologies on fibronectin-coated surfaces, whereas cells spread on surfaces coated with MCT or MEL exhibit strikingly different morphologies. The adhesiveness of MCT, MEL, LHM, and MPF implies that many amphiphilic cationic peptides could prove useful as well defined adhesive substrata for cell culture and for studies of the mechanism of cell adhesion.

  5. Shear-induced adhesion of bacterial cells

    NASA Astrophysics Data System (ADS)

    Lecuyer, Sigolene; Rusconi, Roberto; Shen, Yi; Forsyth, Alison; Stone, Howard

    2009-11-01

    Bacterial adhesion is the first step in the development of surface-associated communities known as biofilms. The formation of these microbial structures is the cause of many different problems in medical devices and industrial water systems. Despite an extensive literature, the underlying mechanisms of the initial reversible attachment are not fully understood. We have investigated the effects of hydrodynamics on the probability of adsorption and detachment of bacteria on model surfaces by using phase-contrast microscopy in straight microchannels. In this way we have been able to measure the time that each bacterium spends on the surface and to analyze the mobility as a function of the flow rate. The main finding of our experiments and analyses is a counter-intuitive enhanced adhesion as the shear stress is increased over a wide range of shear rates.

  6. Xenopus laevis neuronal cell adhesion molecule (nrcam): plasticity of a CAM in the developing nervous system.

    PubMed

    Lokapally, Ashwin; Metikala, Sanjeeva; Hollemann, Thomas

    2017-01-01

    Neuron-glial-related cell adhesion molecule (NRCAM) is a neuronal cell adhesion molecule of the L1 immunoglobulin superfamily, which plays diverse roles during nervous system development including axon growth and guidance, synapse formation, and formation of the myelinated nerve. Perturbations in NRCAM function cause a wide variety of disorders, which can affect wiring and targeting of neurons, or cause psychiatric disorders as well as cancers through abnormal modulation of signaling events. In the present study, we characterize the Xenopus laevis homolog of nrcam. Expression of Xenopus nrcam is most abundant along the dorsal midline throughout the developing brain and in the outer nuclear layer of the retina.

  7. Osteoblastlike cell adhesion on titanium surfaces modified by plasma nitriding.

    PubMed

    da Silva, Jose Sandro Pereira; Amico, Sandro Campos; Rodrigues, Almir Olegario Neves; Barboza, Carlos Augusto Galvao; Alves, Clodomiro; Croci, Alberto Tesconi

    2011-01-01

    The aim of this study was to evaluate the characteristics of various titanium surfaces modified by cold plasma nitriding in terms of adhesion and proliferation of rat osteoblastlike cells. Samples of grade 2 titanium were subjected to three different surface modification processes: polishing, nitriding by plasma direct current, and nitriding by cathodic cage discharge. To evaluate the effect of the surface treatment on the cellular response, the adhesion and proliferation of osteoblastlike cells (MC3T3) were quantified and the results were analyzed by Kruskal-Wallis and Friedman statistical tests. Cellular morphology was observed by scanning electron microscopy. There was more MC3T3 cell attachment on the rougher surfaces produced by cathodic cage discharge compared with polished samples (P < .05). Plasma nitriding improves titanium surface roughness and wettability, leading to osteoblastlike cell adhesion.

  8. Cell Adhesion Molecules and Ubiquitination—Functions and Significance

    PubMed Central

    Homrich, Mirka; Gotthard, Ingo; Wobst, Hilke; Diestel, Simone

    2015-01-01

    Cell adhesion molecules of the immunoglobulin (Ig) superfamily represent the biggest group of cell adhesion molecules. They have been analyzed since approximately 40 years ago and most of them have been shown to play a role in tumor progression and in the nervous system. All members of the Ig superfamily are intensively posttranslationally modified. However, many aspects of their cellular functions are not yet known. Since a few years ago it is known that some of the Ig superfamily members are modified by ubiquitin. Ubiquitination has classically been described as a proteasomal degradation signal but during the last years it became obvious that it can regulate many other processes including internalization of cell surface molecules and lysosomal sorting. The purpose of this review is to summarize the current knowledge about the ubiquitination of cell adhesion molecules of the Ig superfamily and to discuss its potential physiological roles in tumorigenesis and in the nervous system. PMID:26703751

  9. Mechanical integration of actin and adhesion dynamics in cell migration.

    PubMed

    Gardel, Margaret L; Schneider, Ian C; Aratyn-Schaus, Yvonne; Waterman, Clare M

    2010-01-01

    Directed cell migration is a physical process that requires dramatic changes in cell shape and adhesion to the extracellular matrix. For efficient movement, these processes must be spatiotemporally coordinated. To a large degree, the morphological changes and physical forces that occur during migration are generated by a dynamic filamentous actin (F-actin) cytoskeleton. Adhesion is regulated by dynamic assemblies of structural and signaling proteins that couple the F-actin cytoskeleton to the extracellular matrix. Here, we review current knowledge of the dynamic organization of the F-actin cytoskeleton in cell migration and the regulation of focal adhesion assembly and disassembly with an emphasis on how mechanical and biochemical signaling between these two systems regulate the coordination of physical processes in cell migration.

  10. Kindlin-3 Is Essential for the Resting α4β1 Integrin-mediated Firm Cell Adhesion under Shear Flow Conditions.

    PubMed

    Lu, Ling; Lin, ChangDong; Yan, ZhanJun; Wang, Shu; Zhang, YouHua; Wang, ShiHui; Wang, JunLei; Liu, Cui; Chen, JianFeng

    2016-05-06

    Integrin-mediated rolling and firm cell adhesion are two critical steps in leukocyte trafficking. Integrin α4β1 mediates a mixture of rolling and firm cell adhesion on vascular cell adhesion molecule-1 (VCAM-1) when in its resting state but only supports firm cell adhesion upon activation. The transition from rolling to firm cell adhesion is controlled by integrin activation. Kindlin-3 has been shown to bind to integrin β tails and trigger integrin activation via inside-out signaling. However, the role of kindlin-3 in regulating resting α4β1-mediated cell adhesion is not well characterized. Herein we demonstrate that kindlin-3 was required for the resting α4β1-mediated firm cell adhesion but not rolling adhesion. Knockdown of kindlin-3 significantly decreased the binding of kindlin-3 to β1 and down-regulated the binding affinity of the resting α4β1 to soluble VCAM-1. Notably, it converted the resting α4β1-mediated firm cell adhesion to rolling adhesion on VCAM-1 substrates, increased cell rolling velocity, and impaired the stability of cell adhesion. By contrast, firm cell adhesion mediated by Mn(2+)-activated α4β1 was barely affected by knockdown of kindlin-3. Structurally, lack of kindlin-3 led to a more bent conformation of the resting α4β1. Thus, kindlin-3 plays an important role in maintaining a proper conformation of the resting α4β1 to mediate both rolling and firm cell adhesion. Defective kindlin-3 binding to the resting α4β1 leads to a transition from firm to rolling cell adhesion on VCAM-1, implying its potential role in regulating the transition between integrin-mediated rolling and firm cell adhesion.

  11. Endoplasmic Reticulum Calcium, Stress and Cell-to-Cell Adhesion

    PubMed Central

    Mauro, Theodora

    2014-01-01

    Darier's Disease (DD) is caused by mutations in the endoplasmic reticulum (ER) Ca2+ ATPase ATP2A2 (protein SERCA2). Current treatment modalities are ineffective for many patients. This report shows that impaired SERCA2 function, both in DD keratinocytes and in normal keratinocytes treated with the SERCA2-inhibitor thapsigargin, depletes ER Ca2+ stores, leading to constitutive ER stress and increased sensitivity to ER stressors. ER stress, in turn, leads to abnormal cell-to-cell adhesion via impaired redistribution of desmoplakin, desmoglein 3, desmocollin 3 and E-cadherin to the plasma membrane. This report illustrates how ER Ca2+ depletion and the resulting ER stress are central to the pathogenesis of the disease. Additionally, the authors introduce a possible new therapeutic agent, Miglustat. PMID:24924761

  12. Activation of the δ-opioid receptor promotes cutaneous wound healing by affecting keratinocyte intercellular adhesion and migration

    PubMed Central

    Bigliardi, P L; Neumann, C; Teo, Y L; Pant, A; Bigliardi-Qi, M

    2015-01-01

    BACKGROUND AND PURPOSE In addition to its analgesic functions, the peripheral opioid receptor system affects skin homeostasis by influencing cell differentiation, migration and adhesion; also, wound healing is altered in δ-opioid receptor knockout mice (DOPr–/–). Hence, we investigated δ-opioid receptor effects on the expression of several proteins of the desmosomal junction complex and on the migratory behaviour of keratinocytes. EXPERIMENTAL APPROACH Expression levels of desmosomal cadherins in wild-type and DOPr–/– mice, and the morphology of intercellular adhesion in human keratinocytes were analysed by immunofluorescence. To investigate the δ-opioid receptor activation pathway, protein expression was studied using Western blot and its effect on cellular migration determined by in vitro live cell migration recordings from human keratinocytes. KEY RESULTS Expression of the desmosomal cadherins, desmogleins 1 and 4, was up-regulated in skin from DOPr–/– mice, and down-regulated in δ-opioid receptor-overexpressing human keratinocytes. The localization of desmoplakin expression was rearranged from linear arrays emanating from cell borders to puncta in cell periphery, resulting in less stable intercellular adhesion. Migration and wound recovery were enhanced in human keratinocyte monolayers overexpressing δ-opioid receptors in vitro. These δ-opioid receptor effects were antagonized by specific PKCα/β inhibition indicating they were mediated through the PKC signalling pathway. Finally, cells overexpressing δ-opioid receptors developed characteristically long but undirected protrusions containing filamentous actin and δ-opioid receptors, indicating an enhanced migratory phenotype. CONCLUSION AND IMPLICATIONS Opioid receptors affect intercellular adhesion and wound healing mechanisms, underlining the importance of a cutaneous neuroendocrine system in wound healing and skin homeostasis. LINKED ARTICLES This article is part of a themed section on

  13. Activation of the δ-opioid receptor promotes cutaneous wound healing by affecting keratinocyte intercellular adhesion and migration.

    PubMed

    Bigliardi, P L; Neumann, C; Teo, Y L; Pant, A; Bigliardi-Qi, M

    2015-01-01

    In addition to its analgesic functions, the peripheral opioid receptor system affects skin homeostasis by influencing cell differentiation, migration and adhesion; also, wound healing is altered in δ-opioid receptor knockout mice (DOPr(-/-) ). Hence, we investigated δ-opioid receptor effects on the expression of several proteins of the desmosomal junction complex and on the migratory behaviour of keratinocytes. Expression levels of desmosomal cadherins in wild-type and DOPr(-/-) mice, and the morphology of intercellular adhesion in human keratinocytes were analysed by immunofluorescence. To investigate the δ-opioid receptor activation pathway, protein expression was studied using Western blot and its effect on cellular migration determined by in vitro live cell migration recordings from human keratinocytes. Expression of the desmosomal cadherins, desmogleins 1 and 4, was up-regulated in skin from DOPr(-/-) mice, and down-regulated in δ-opioid receptor-overexpressing human keratinocytes. The localization of desmoplakin expression was rearranged from linear arrays emanating from cell borders to puncta in cell periphery, resulting in less stable intercellular adhesion. Migration and wound recovery were enhanced in human keratinocyte monolayers overexpressing δ-opioid receptors in vitro. These δ-opioid receptor effects were antagonized by specific PKCα/β inhibition indicating they were mediated through the PKC signalling pathway. Finally, cells overexpressing δ-opioid receptors developed characteristically long but undirected protrusions containing filamentous actin and δ-opioid receptors, indicating an enhanced migratory phenotype. Opioid receptors affect intercellular adhesion and wound healing mechanisms, underlining the importance of a cutaneous neuroendocrine system in wound healing and skin homeostasis. This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http

  14. Prostaglandins in Cancer Cell Adhesion, Migration, and Invasion

    PubMed Central

    Menter, David G.; DuBois, Raymond N.

    2012-01-01

    Prostaglandins exert a profound influence over the adhesive, migratory, and invasive behavior of cells during the development and progression of cancer. Cyclooxygenase-2 (COX-2) and microsomal prostaglandin E2 synthase-1 (mPGES-1) are upregulated in inflammation and cancer. This results in the production of prostaglandin E2 (PGE2), which binds to and activates G-protein-coupled prostaglandin E1–4 receptors (EP1–4). Selectively targeting the COX-2/mPGES-1/PGE2/EP1–4 axis of the prostaglandin pathway can reduce the adhesion, migration, invasion, and angiogenesis. Once stimulated by prostaglandins, cadherin adhesive connections between epithelial or endothelial cells are lost. This enables cells to invade through the underlying basement membrane and extracellular matrix (ECM). Interactions with the ECM are mediated by cell surface integrins by “outside-in signaling” through Src and focal adhesion kinase (FAK) and/or “inside-out signaling” through talins and kindlins. Combining the use of COX-2/mPGES-1/PGE2/EP1–4 axis-targeted molecules with those targeting cell surface adhesion receptors or their downstream signaling molecules may enhance cancer therapy. PMID:22505934

  15. Galaptin Mediates the Effect of Hypergravity on Vascular Smooth Muscle cell (SMC) Adhesion to Laminin Containing Matrices

    NASA Technical Reports Server (NTRS)

    Enahora, Fatisha T.; Bosah, Francis N.; Harris-Hooker, Sandra; Sanford, Gary L.

    1997-01-01

    Galaptin, an endogenous beta-galactoside specific lectin, has been reported to bind to laminin and subsequently decrease the binding of SMC. Cellular function depend on cell:matrix interactions. Hypergravity (HGrav) affect a number of cellular functions, yet little is known about its affect on cell adhesion. We examined the possibility that galaptin mediates the effects of hypergravity on SMC adherence. Confluent primate aorta SMC cultures were subjected to Hgrav (centrifuged at 6G) for 24 and 48 hr. Cells were non-enzymatically dispersed, pretreated with antisense (AS-oligo) or control sense (SS-oligo) oligonucleotides to galaptin mRNA (0.01 micro g/ml), then seeded in uncoated or ECL-matrix coated plates. Adhesion of cells were monitored after 6 hr. HGrav increased adhesion by 100-300% compared to controls. AS-oligo decreased adhesion for both HGrav and control cells. SS-oligo did not affect adhesion for either HGrav or control cells. These studies show that HGrav affects cell adhesion and that galaptin expression is required for this effect.

  16. Galaptin Mediates the Effect of Hypergravity on Vascular Smooth Muscle cell (SMC) Adhesion to Laminin Containing Matrices

    NASA Technical Reports Server (NTRS)

    Enahora, Fatisha T.; Bosah, Francis N.; Harris-Hooker, Sandra; Sanford, Gary L.

    1997-01-01

    Galaptin, an endogenous beta-galactoside specific lectin, has been reported to bind to laminin and subsequently decrease the binding of SMC. Cellular function depend on cell:matrix interactions. Hypergravity (HGrav) affect a number of cellular functions, yet little is known about its affect on cell adhesion. We examined the possibility that galaptin mediates the effects of hypergravity on SMC adherence. Confluent primate aorta SMC cultures were subjected to Hgrav (centrifuged at 6G) for 24 and 48 hr. Cells were non-enzymatically dispersed, pretreated with antisense (AS-oligo) or control sense (SS-oligo) oligonucleotides to galaptin mRNA (0.01 micro g/ml), then seeded in uncoated or ECL-matrix coated plates. Adhesion of cells were monitored after 6 hr. HGrav increased adhesion by 100-300% compared to controls. AS-oligo decreased adhesion for both HGrav and control cells. SS-oligo did not affect adhesion for either HGrav or control cells. These studies show that HGrav affects cell adhesion and that galaptin expression is required for this effect.

  17. Surface roughness rather than surface chemistry essentially affects insect adhesion

    PubMed Central

    England, Matt W; Sato, Tomoya; Yagihashi, Makoto; Gorb, Stanislav N

    2016-01-01

    Summary The attachment ability of ladybird beetles Coccinella septempunctata was systematically investigated on eight types of surface, each with different chemical and topographical properties. The results of traction force tests clearly demonstrated that chemical surface properties, such as static/dynamic de-wettability of water and oil caused by specific chemical compositions, had no significant effect on the attachment of the beetles. Surface roughness was found to be the dominant factor, strongly affecting the attachment ability of the beetles. PMID:27826522

  18. Surface roughness rather than surface chemistry essentially affects insect adhesion.

    PubMed

    England, Matt W; Sato, Tomoya; Yagihashi, Makoto; Hozumi, Atsushi; Gorb, Stanislav N; Gorb, Elena V

    2016-01-01

    The attachment ability of ladybird beetles Coccinella septempunctata was systematically investigated on eight types of surface, each with different chemical and topographical properties. The results of traction force tests clearly demonstrated that chemical surface properties, such as static/dynamic de-wettability of water and oil caused by specific chemical compositions, had no significant effect on the attachment of the beetles. Surface roughness was found to be the dominant factor, strongly affecting the attachment ability of the beetles.

  19. A stochastic model for adhesion-mediated cell random motility and haptotaxis.

    PubMed

    Dickinson, R B; Tranquillo, R T

    1993-01-01

    The active migration of blood and tissue cells is important in a number of physiological processes including inflammation, wound healing, embryogenesis, and tumor cell metastasis. These cells move by transmitting cytoplasmic force through membrane receptors which are bound specifically to adhesion ligands in the surrounding substratum. Recently, much research has focused on the influence of the composition of extracellular matrix and the distribution of its components on the speed and direction of cell migration. It is commonly believed that the magnitude of the adhesion influences cell speed and/or random turning behavior, whereas a gradient of adhesion may bias the net direction of the cell movement, a phenomenon known as haptotaxis. The mechanisms underlying these responses are presently not understood. A stochastic model is presented to provide a mechanistic understanding of how the magnitude and distribution of adhesion ligands in the substratum influence cell movement. The receptor-mediated cell migration is modeled as an interrelation of random processes on distinct time scales. Adhesion receptors undergo rapid binding and transport, resulting in a stochastic spatial distribution of bound receptors fluctuating about some mean distribution. This results in a fluctuating spatio-temporal pattern of forces on the cell, which in turn affects the speed and turning behavior on a longer time scale. The model equations are a system of nonlinear stochastic differential equations (SDE's) which govern the time evolution of the spatial distribution of bound and free receptors, and the orientation and position of the cell. These SDE's are integrated numerically to simulate the behavior of the model cell on both a uniform substratum, and on a gradient of adhesion ligand concentration. Furthermore, analysis of the governing SDE system and corresponding Fokker-Planck equation (FPE) yields analytical expressions for indices which characterize cell movement on multiple time

  20. Cell-cell adhesion in the cnidaria: insights into the evolution of tissue morphogenesis.

    PubMed

    Magie, Craig R; Martindale, Mark Q

    2008-06-01

    Cell adhesion is a major aspect of cell biology and one of the fundamental processes involved in the development of a multicellular animal. Adhesive mechanisms, both cell-cell and between cell and extracellular matrix, are intimately involved in assembling cells into the three-dimensional structures of tissues and organs. The modulation of adhesive complexes could therefore be seen as a central component in the molecular control of morphogenesis, translating information encoded within the genome into organismal form. The availability of whole genomes from early-branching metazoa such as cnidarians is providing important insights into the evolution of adhesive processes by allowing for the easy identification of the genes involved in adhesion in these organisms. Discovery of the molecular nature of cell adhesion in the early-branching groups, coupled with comparisons across the metazoa, is revealing the ways evolution has tinkered with this vital cellular process in the generation of the myriad forms seen across the animal kingdom.

  1. Osteopontin O-glycosylation contributes to its phosphorylation and cell-adhesion properties.

    PubMed

    Kariya, Yoshinobu; Kanno, Mayumi; Matsumoto-Morita, Kana; Konno, Midori; Yamaguchi, Yoshiki; Hashimoto, Yasuhiro

    2014-10-01

    OPN (osteopontin) is a multiphosphorylated extracellular glycoprotein, which has important roles in bone remodelling, inflammation and cancer metastasis. OPN regulates cell spreading and adhesion primarily through its association with several integrins such as αvβ3, and its phosphorylation affects these processes. However, the mechanism by which OPN O-glycosylation affects these processes is not completely understood. In the present study, we demonstrated that OPN O-glycosylation self-regulates its biological activities and also affects its phosphorylation status. We prepared two recombinant OPNs, WT (wild-type)-OPN and mutant OPN (ΔO-OPN), which lacks five O-glycosylation sites at a threonine/proline-rich region. O-glycan defects in OPN increased its phosphorylation level, as observed by dephosphorylation assays. Moreover, compared with WT-OPN, ΔO-OPN exhibited enhanced cell spreading and adhesion activities and decreased associations with β1 integrins. This suggested that defects in O-glycans in OPN altered these activities, and that β1 integrins have a less important role in adhesion to ΔO-OPN. The cell-adhesion activity of dephosphorylated ΔO-OPN was higher than the cell-adhesion activities of ΔO-OPN and dephosphorylated WT-OPN. This suggested that some of the phosphorylation in ΔO-OPN caused by O-glycan defects and O-glycans of OPN suppressed the OPN cell-adhesion activity. Thus functional activities of OPN can be determined by the combined glycosylation and phosphorylation statuses and not by either status alone.

  2. Inhibitor of DASH proteases affects expression of adhesion molecules in osteoclasts and reduces myeloma growth and bone disease.

    PubMed

    Pennisi, Angela; Li, Xin; Ling, Wen; Khan, Sharmin; Gaddy, Dana; Suva, Larry J; Barlogie, Bart; Shaughnessy, John D; Aziz, Nazneen; Yaccoby, Shmuel

    2009-06-01

    Dipeptidyl peptidase (DPP) IV activity and/or structure homologues (DASH) are serine proteases implicated in tumourigenesis. We previously found that a DASH protease, fibroblast activation protein (FAP), was involved in osteoclast-induced myeloma growth. Here we further demonstrated expression of various adhesion molecules in osteoclasts cultured alone or cocultured with myeloma cells, and tested the effects of DASH inhibitor, PT-100, on myeloma cell growth, bone disease, osteoclast differentiation and activity, and expression of adhesion molecules in osteoclasts. PT-100 had no direct effects on viability of myeloma cells or mature osteoclasts, but significantly reduced survival of myeloma cells cocultured with osteoclasts. Real-time PCR array for 85 adhesion molecules revealed upregulation of 17 genes in osteoclasts after coculture with myeloma cells. Treatment of myeloma/osteoclast cocultures with PT-100 significantly downregulated 18 of 85 tested genes in osteoclasts, some of which are known to play roles in tumourigenesis and osteoclastogenesis. PT-100 also inhibited osteoclast differentiation and subsequent pit formation. Resorption activity of mature osteoclasts and differentiation of osteoblasts were not affected by PT-100. In primary myelomatous severe combined immunodeficient (SCID)-hu mice PT-100 reduced osteoclast activity, bone resorption and tumour burden. These data demonstrated that DASH proteases are involved in myeloma bone disease and tumour growth.

  3. Eosinophils adhere to vascular cell adhesion molecule-1 via podosomes.

    PubMed

    Johansson, Mats W; Lye, Ming H; Barthel, Steven R; Duffy, Allison K; Annis, Douglas S; Mosher, Deane F

    2004-10-01

    Vascular cell adhesion molecule (VCAM)-1 supports specific eosinophil adhesion via alpha4beta1 integrin. We tested the hypothesis that adhesive contacts formed by eosinophils on VCAM-1 are different from focal adhesions formed by adherent fibroblasts. Eosinophils adherent on VCAM-1 formed punctate adhesions that fit the criteria for podosomes, highly dynamic structures found in adherent transformed fibroblasts, osteoclasts, and macrophages. The structures contained beta1 integrin subunit, phosphotyrosine-containing proteins, punctate filamentous actin, and gelsolin, a podosome marker. In contrast, nontransformed fibroblasts on VCAM-1 formed peripheral focal adhesions that were positive for alpha4, beta1, phosphotyrosine, vinculin, talin, and paxillin; negative for gelsolin; and associated with microfilaments. Phorbol myristate acetate or tumor necrosis factor-alpha and interleukin-5 stimulated podosome formation in adherent eosinophils. Because podosomes in tumor cells are associated with extracellular matrix degradation, we analyzed the VCAM-1 layer. VCAM-1 was lost under adherent eosinophils but not under adherent fibroblasts. This loss was inhibited by the metalloproteinase inhibitor ortho-phenanthroline and correlated with expression and podosome localization of a membrane-tethered metalloproteinase, a disintegrin and metalloproteinase domain 8. Podosome-mediated VCAM-1 clearance may be a mechanism to regulate eosinophil arrest and extravasation in allergic conditions such as asthma.

  4. Identification of a peptide sequence involved in homophilic binding in the neural cell adhesion molecule NCAM

    PubMed Central

    1992-01-01

    The neural cell adhesion molecule NCAM is capable of mediating cell- cell adhesion via homophilic interactions. In this study, three strategies have been combined to identify regions of NCAM that participate directly in NCAM-NCAM binding: analysis of domain deletion mutations, mapping of epitopes of monoclonal antibodies, and use of synthetic peptides to inhibit NCAM activity. Studies on L cells transfected with NCAM mutant cDNAs using cell aggregation and NCAM- covasphere binding assays indicate that the third immunoglobulin-like domain is involved in homophilic binding. The epitopes of four monoclonal antibodies that have been previously shown to affect cell- cell adhesion mediated by NCAM were also mapped to domain 3. Overlapping hexapeptides were synthesized on plastic pins and assayed for binding with these monoclonal antibodies. One of them (PP) reacted specifically with the sequence KYSFNY. Synthetic oligopeptides containing the PP epitope were potent and specific inhibitors of NCAM binding activity. A substratum containing immobilized peptide conjugates also exhibited adhesiveness for neural retinal cells. Cell attachment was specifically inhibited by peptides that contained the PP- epitope and by anti-NCAM univalent antibodies. The shortest active peptide has the sequence KYSFNYDGSE, suggesting that this site is directly involved in NCAM homophilic interaction. PMID:1380002

  5. Chronic restraint stress down-regulates amygdaloid expression of polysialylated neural cell adhesion molecule.

    PubMed

    Cordero, M I; Rodríguez, J J; Davies, H A; Peddie, C J; Sandi, C; Stewart, M G

    2005-01-01

    The amygdala is a brain area which plays a decisive role in fear and anxiety. Since exposure to chronic stress can induce profound effects in emotion and cognition, plasticity in specific amygdaloid nuclei in response to prior stress has been hypothesized to account for stress-induced emotional alterations. In order to identify amygdala nuclei which may be affected under chronic stress conditions we evaluated the effects of 21-days chronic restraint stress on the expression of a molecule implicated crucially in alterations in structural plasticity: the polysialylated neural cell adhesion molecule. We found that polysialylated neural cell adhesion molecule-immunoreactivity within the amygdala, present in somata and neuronal processes, has a regional gradient with the central medial and medial amygdaloid nuclei showing the highest levels. Our results demonstrate that chronic restraint stress induced an overall reduction in polysialylated neural cell adhesion molecule-immunoreactivity in the amygdaloid complex, mainly due to a significant decrease in the central medial amygdaloid and medial amygdaloid nuclei. Our data suggest that polysialylated neural cell adhesion molecule in these nuclei may play a prominent role in functional and structural remodeling induced by stress, being a potential mechanism for cognitive and emotional modulation. Furthermore, these finding provide the first clear evidence that life experiences can regulate the expression of polysialylated neural cell adhesion molecule in the amygdaloid complex.

  6. Why do receptor–ligand bonds in cell adhesion cluster into discrete focal-adhesion sites?

    DOE PAGES

    Gao, Zhiwen; Gao, Yanfei

    2016-05-14

    We report that cell adhesion often exhibits the clustering of the receptor–ligand bonds into discrete focal-adhesion sites near the contact edge, thus resembling a rosette shape or a contracting membrane anchored by a small number of peripheral forces. The ligands on the extracellular matrix are immobile, and the receptors in the cell plasma membrane consist of two types: high-affinity integrins (that bond to the substrate ligands and are immobile) and low-affinity integrins (that are mobile and not bonded to the ligands). Thus the adhesion energy density is proportional to the high-affinity integrin density. This paper provides a mechanistic explanation formore » the clustering/assembling of the receptor–ligand bonds from two main points: (1) the cellular contractile force leads to the density evolution of these two types of integrins, and results into a large high-affinity integrin density near the contact edge and (2) the front of a propagating crack into a decreasing toughness field will be unstable and wavy. From this fracture mechanics perspective, the chemomechanical equilibrium is reached when a small number of patches with large receptor–ligand bond density are anticipated to form at the cell periphery, as opposed to a uniform distribution of bonds on the entire interface. Finally, cohesive fracture simulations show that the de-adhesion force can be significantly enhanced by this nonuniform bond density field, but the de-adhesion force anisotropy due to the substrate elastic anisotropy is significantly reduced.« less

  7. Cell-substrate impedance fluctuations of single amoeboid cells encode cell-shape and adhesion dynamics

    NASA Astrophysics Data System (ADS)

    Leonhardt, Helmar; Gerhardt, Matthias; Höppner, Nadine; Krüger, Kirsten; Tarantola, Marco; Beta, Carsten

    2016-01-01

    We show systematic electrical impedance measurements of single motile cells on microelectrodes. Wild-type cells and mutant strains were studied that differ in their cell-substrate adhesion strength. We recorded the projected cell area by time-lapse microscopy and observed irregular oscillations of the cell shape. These oscillations were correlated with long-term variations in the impedance signal. Superposed to these long-term trends, we observed fluctuations in the impedance signal. Their magnitude clearly correlated with the adhesion strength, suggesting that strongly adherent cells display more dynamic cell-substrate interactions.

  8. Hybrid inverse opals for regulating cell adhesion and orientation

    NASA Astrophysics Data System (ADS)

    Lu, Jie; Zheng, Fuyin; Cheng, Yao; Ding, Haibo; Zhao, Yuanjin; Gu, Zhongze

    2014-08-01

    Cell adhesion and alignment are two important considerations in tissue engineering applications as they can regulate the subsequent cell proliferation activity and differentiation program. Although many effects have been applied to regulate the adhesion or alignment of cells by using physical and chemical methods, it is still a challenge to regulate these cell behaviors simultaneously. Here, we present novel substrates with tunable nanoscale patterned structures for regulating the adhesion and alignment of cells. The substrates with different degrees of pattern orientation were achieved by customizing the amount of stretching applied to polymer inverse opal films. Cells cultured on these substrates showed an adjustable morphology and alignment. Moreover, soft hydrogels, which have poor plasticity and are difficult to cast into patterned structures, were applied to infiltrate the inverse opal structure. We demonstrated that the adhesion ratio of cells could be regulated by these hybrid substrates, as well as adjusting the cell morphology and alignment. These features of functional inverse opal substrates make them suitable for important applications in tissue engineering.

  9. Hybrid inverse opals for regulating cell adhesion and orientation.

    PubMed

    Lu, Jie; Zheng, Fuyin; Cheng, Yao; Ding, Haibo; Zhao, Yuanjin; Gu, Zhongze

    2014-09-21

    Cell adhesion and alignment are two important considerations in tissue engineering applications as they can regulate the subsequent cell proliferation activity and differentiation program. Although many effects have been applied to regulate the adhesion or alignment of cells by using physical and chemical methods, it is still a challenge to regulate these cell behaviors simultaneously. Here, we present novel substrates with tunable nanoscale patterned structures for regulating the adhesion and alignment of cells. The substrates with different degrees of pattern orientation were achieved by customizing the amount of stretching applied to polymer inverse opal films. Cells cultured on these substrates showed an adjustable morphology and alignment. Moreover, soft hydrogels, which have poor plasticity and are difficult to cast into patterned structures, were applied to infiltrate the inverse opal structure. We demonstrated that the adhesion ratio of cells could be regulated by these hybrid substrates, as well as adjusting the cell morphology and alignment. These features of functional inverse opal substrates make them suitable for important applications in tissue engineering.

  10. Epithelial cell adhesion and gastrointestinal colonization of Lactobacillus in poultry.

    PubMed

    Spivey, Megan A; Dunn-Horrocks, Sadie L; Duong, Tri

    2014-11-01

    Administration of probiotic Lactobacillus cultures is an important alternative to the use of antibiotic growth promoters and has been demonstrated to improve animal health, growth performance, and preharvest food safety in poultry production. Whereas gastrointestinal colonization is thought to be critical to their probiotic functionality, factors important to Lactobacillus colonization in chickens are not well understood. In this study we investigate epithelial cell adhesion in vitro and colonization of Lactobacillusin vivo in broiler chickens. Adhesion of Lactobacillus cultures to epithelial cells was evaluated using the chicken LMH cell line. Lactobacillus cultures were able adhere effectively to LMH cells relative to Bacillus subtilis and Salmonella Typhimurium. Epithelial cell adhesion was similar for Lactobacillus crispatus TDCC 75, L. cristpatus TDCC 76, and Lactobacillus gallinarum TDCC 77, and all 3 were more adherent than L. gallinarum TDCC 78. However, when colonization was evaluated in the ileum and cecum of broiler chicks, L. crispatus TDCC 75 and L. gallinarum TDCC 77 were more persistent than L. crispatus TDCC 76 and L. gallinarum TDCC 78. The reduction of growth in medium supplemented with oxgal was greater for L. gallinarum TDCC 78 than L. gallinarum TDCC 77, suggesting that whereas adhesion was similar for the 2 strains, the difference in colonization between L. gallinarum strains may be due in part to their bile sensitivity. This study demonstrates that whereas adhesion to epithelial cells may be important in predicting gastrointestinal colonization, other factors including bile tolerance may also contribute to the colonization of Lactobacillus in poultry. Additionally, the chicken LMH cell line is expected to provide a platform for investigating mechanisms of Lactobacillus adhesion to epithelial tissue and evaluating the probiotic potential Lactobacillus in poultry.

  11. Graphical analysis of mammalian cell adhesion in vitro.

    PubMed

    Huang, Qiaoling; Antensteiner, Martin; Liu, Xiang Yang; Lin, Changjian; Vogler, Erwin A

    2016-12-01

    Short-term (<2h) cell adhesion kinetics of 3 different mammalian cell types: MDCK (epithelioid), MC3T3-E1 (osteoblastic), and MDA-MB-231 (cancerous) on 7 different substratum surface chemistries spanning the experimentally-observable range of water wettability (surface energy) are graphically analyzed to qualitatively elucidate commonalities and differences among cell/surface/suspending media combinations. We find that short-term mammalian cell attachment/adhesion in vitro correlates with substratum surface energy as measured by water adhesion tension, τ≡γlvcosθ, where γlv is water liquid-vapor interfacial energy (72.8   mJ/m(2)) and cosθ is the cosine of the advancing contact angle subtended by a water droplet on the substratum surface. No definitive functional relationships among cell-adhesion kinetic parameters and τ were observed as in previous work, but previously-observed general trends were reproduced, especially including a sharp transition in the magnitude of kinetic parameters from relatively low-to-high near τ=0mJ/m(2), although the exact adhesion tension at which this transition occurs is difficult to accurately estimate from the current data set. We note, however, that the transition is within the hydrophobic range based on the τ=30mJ/m(2) surface-energetic dividing line that has been proposed to differentiate "hydrophobic" surfaces from "hydrophilic". Thus, a rather sharp hydrophobic/hydrophilic contrast is observed for cell adhesion for disparate cell/surface combinations.

  12. Lymphocyte adhesion-dependent calcium signaling in human endothelial cells

    PubMed Central

    1995-01-01

    Vascular endothelial cells (ECs) can undergo dramatic phenotypic and functional alterations in response to humoral and cellular stimuli. These changes promote endothelial participation in the inflammatory response through active recruitment of immune effector cells, increased vascular permeability, and alteration in vascular tone. In an attempt to define early events in lymphocyte-mediated EC signaling, we investigated cytosolic-free calcium (Ca2+) changes in single, Fluo-3- labeled human umbilical vein ECs (HUVECs), using an ACAS interactive laser cytometer. Of all lymphocyte subsets tested, allogeneic CD3-, CD56+ natural killer (NK) cells uniquely elicited oscillatory EC Ca2+ signals in cytokine (interleukin [IL]-1- or tumor necrosis factor [TNF])-treated ECs. The induction of these signals required avid intercellular adhesion, consisted of both Ca2+ mobilization and extracellular influx, and was associated with EC inositol phosphate (IP) generation. Simultaneous recording of NK and EC Ca2+ signals using two-color fluorescence detection revealed that, upon adhesion, NK cells flux prior to EC. Lymphocyte Ca2+ buffering with 1,2-bis-5-methyl-amino- phenoxylethane-N,N,N'-tetra-acetoxymethyl acetate (MAPTAM) demonstrated that lymphocyte fluxes are, in fact, prerequisites for the adhesion- dependent EC signals. mAb studies indicate that the beta 2 integrin- intercellular adhesion molecule (ICAM)-1 adhesion pathway is critically involved. However, ICAM-1 antisense oligonucleotide inhibition of IL-1- mediated ICAM-1 hyperinduction had no effect on EC Ca2+ signaling in lymphocyte-EC conjugates, indicating that additional cytokine-induced EC alteration is required. These experiments combine features of lymphocyte-endothelial interactions, intercellular adhesion, EC cytokine activation and transmembrane signaling. The results implicate the IP/Ca2+ second messenger pathway in EC outside-in signaling induced by cytotoxic lymphocytes, and suggest that these signals may play a

  13. Flexible nanopillars to regulate cell adhesion and movement

    NASA Astrophysics Data System (ADS)

    Chien, Fan-Ching; Dai, Yang-Hong; Kuo, Chiung Wen; Chen, Peilin

    2016-11-01

    Flexible polymer nanopillar substrates were used to systematically demonstrate cell alignment and migration guided by the directional formation of focal adhesions. The polymer nanopillar substrates were constructed to various height specifications to provide an extensive variation of flexibility; a rectangular arrangement created spatial confinement between adjacent nanopillars, providing less spacing in the horizontal and vertical directions. Three polymer nanopillar substrates with the diameter of 400 nm and the heights of 400, 800, and 1200 nm were fabricated. Super-resolution localization imaging and protein pair-distance analysis of vinculin proteins revealed that Chinese hamster ovary (CHO) cells formed mature focal adhesions on 1200 nm high nanopillar substrates by bending adjacent nanopillars to link dot-like adhesions. The spacing confinement of the adjacent nanopillars enhanced the orthogonal directionality of the formation tendency of the mature focal adhesions. The directional formation of the mature focal adhesions also facilitated the organization of actin filaments in the horizontal and vertical directions. Moreover, 78% of the CHO cells were aligned in these two directions, in conformity with the flexibility and nanotopographical cues of the nanopillars. Biased cell migration was observed on the 1200 nm high nanopillar substrates.

  14. Adhesion of platelets to artificial surfaces: effect of red cells.

    PubMed

    Brash, J L; Brophy, J M; Feuerstein, I A

    1976-05-01

    Adhesion of platelets to several polymer- and protein-coated glass surfaces has been studied in vitro. The apparatus consists of a cylindrical probe rotating in a test tube containing the platelet medium and allows close control of fluid shear and mass transport. Suspensions of washed pig platelets constitute the basic platelet medium, and can be modified by adding back red cells and plasma proteins. Adhesion is measured via 51Cr-labeling of platelets. In the absence of red cells, identical low levels of adhesion were seen on all surfaces and saturation was reached within 2 min. In the presence of red cells, adhesion was greater. Saturation on all surfaces except fibrinogen and collagen again occurred within 2 min. The adhesion levels on polymer surfaces and glass were indistinguishable, while those on albumin were lower and those on fibrinogen were higher. Collagen was the most reactive surface. It did not equilibrate within 15 min., and kinetic data indicated a platelet diffusivity strongly dependent on hematocrit. These effects were attributed to rotational and translational motion of the red cells causing increased diffusion and surface-platelet collision energy.

  15. Spatially controlled cell adhesion on three-dimensional substrates.

    PubMed

    Richter, Christine; Reinhardt, Martina; Giselbrecht, Stefan; Leisen, Daniel; Trouillet, Vanessa; Truckenmüller, Roman; Blau, Axel; Ziegler, Christiane; Welle, Alexander

    2010-10-01

    The microenvironment of cells in vivo is defined by spatiotemporal patterns of chemical and biophysical cues. Therefore, one important goal of tissue engineering is the generation of scaffolds with defined biofunctionalization in order to control processes like cell adhesion and differentiation. Mimicking extrinsic factors like integrin ligands presented by the extracellular matrix is one of the key elements to study cellular adhesion on biocompatible scaffolds. By using special thermoformable polymer films with anchored biomolecules micro structured scaffolds, e.g. curved and micro-patterned substrates, can be fabricated. Here, we present a novel strategy for the fabrication of micro-patterned scaffolds based on the "Substrate Modification and Replication by Thermoforming" (SMART) technology: The surface of a poly lactic acid membrane, having a low forming temperature of 60 degrees C and being initially very cell attractive, was coated with a photopatterned layer of poly(L-lysine) (PLL) and hyaluronic acid (VAHyal) to gain spatial control over cell adhesion. Subsequently, this modified polymer membrane was thermoformed to create an array of spherical microcavities with diameters of 300 microm for 3D cell culture. Human hepatoma cells (HepG2) and mouse fibroblasts (L929) were used to demonstrate guided cell adhesion. HepG2 cells adhered and aggregated exclusively within these cavities without attaching to the passivated surfaces between the cavities. Also L929 cells adhering very strongly on the pristine substrate polymer were effectively patterned by the cell repellent properties of the hyaluronic acid based hydrogel. This is the first time cell adhesion was controlled by patterned functionalization of a polymeric substrate with UV curable PLL-VAHyal in thermoformed 3D microstructures.

  16. Spatially controlled cell adhesion on three-dimensional substrates

    PubMed Central

    Richter, Christine; Reinhardt, Martina; Giselbrecht, Stefan; Leisen, Daniel; Trouillet, Vanessa; Truckenmüller, Roman; Blau, Axel; Ziegler, Christiane

    2010-01-01

    The microenvironment of cells in vivo is defined by spatiotemporal patterns of chemical and biophysical cues. Therefore, one important goal of tissue engineering is the generation of scaffolds with defined biofunctionalization in order to control processes like cell adhesion and differentiation. Mimicking extrinsic factors like integrin ligands presented by the extracellular matrix is one of the key elements to study cellular adhesion on biocompatible scaffolds. By using special thermoformable polymer films with anchored biomolecules micro structured scaffolds, e.g. curved and µ-patterned substrates, can be fabricated. Here, we present a novel strategy for the fabrication of µ-patterned scaffolds based on the “Substrate Modification and Replication by Thermoforming” (SMART) technology: The surface of a poly lactic acid membrane, having a low forming temperature of 60°C and being initially very cell attractive, was coated with a photopatterned layer of poly(L-lysine) (PLL) and hyaluronic acid (VAHyal) to gain spatial control over cell adhesion. Subsequently, this modified polymer membrane was thermoformed to create an array of spherical microcavities with diameters of 300 µm for 3D cell culture. Human hepatoma cells (HepG2) and mouse fibroblasts (L929) were used to demonstrate guided cell adhesion. HepG2 cells adhered and aggregated exclusively within these cavities without attaching to the passivated surfaces between the cavities. Also L929 cells adhering very strongly on the pristine substrate polymer were effectively patterned by the cell repellent properties of the hyaluronic acid based hydrogel. This is the first time cell adhesion was controlled by patterned functionalization of a polymeric substrate with UV curable PLL-VAHyal in thermoformed 3D microstructures. PMID:20480241

  17. Subnanometric Roughness Affects the Deposition and Mobile Adhesion of Escherichia coli on Silanized Glass Surfaces.

    PubMed

    Sharma, Sumedha; Jaimes-Lizcano, Yuly Andrea; McLay, Ryan B; Cirino, Patrick C; Conrad, Jacinta C

    2016-05-31

    We investigate the deposition and transient adhesion of Escherichia coli on alkyl and fluoroalkyl silanized glass surfaces of different carbon chain lengths. The rate at which bacteria deposit onto these surfaces decreases as the shear stress is increased from 3 to 67 mPa, but trends in the deposition rate across all surfaces cannot be predicted from extended DLVO calculations of the interaction potential. As the surface root-mean-square (rms) roughness increases, the deposition rate increases and the percentage of motile tethered cells decreases. Furthermore, on surfaces of root-mean-square roughness of less than 0.2 nm, bacteria exhibit mobile adhesion, for which surface-associated cells linearly translate distances greater than approximately 1.5 times their average body length along the flow direction. E. coli bacteria with and without flagella exhibit mobile adhesion, indicating that this behavior is not driven by these appendages. Cells that express fimbriae do not exhibit mobile adhesion. These results suggest that even subnanoscale roughness can influence the deposition and transient adhesion of bacteria and imply that strategies to reduce frictional interactions by making cells or surfaces smoother may help to control the initial fouling of surfaces by E. coli bacteria.

  18. Evaluation of the Correlation between Focal Adhesion Kinase Phosphorylation and Cell Adhesion Force Using “DEP” Technology

    PubMed Central

    Ay, Chyung; Yeh, Chih-Chang; Hsu, Min-Chih; Hurng, Huaang-Youh; Kwok, Philip Chi Lip; Chang, Hsin-I.

    2012-01-01

    Dielectrophoresis (DEP) is the phenomenon in which a particle, such as a living cell, is polarized and moved by electrical gravity in a non-uniform electric field. In the present study, the DEP force is utilized to act on the cells to induce spatial movement for investigating the correlation between the cell adhesion force and activation level of focal adhesion kinase (FAK). The DEP force produced by the non-uniform electric field was used to measure the cell adhesion force of ECV304 cells, on type 1 collagen (COL1)- and fibronectin (FN)-coated polydimethylsiloxane (PDMS) membranes. For COL1-coating, ECV304 cells revealed weak and variable adhesion force (0.343–0.760 nN) in the first eight hours of incubation. Interestingly, the cell adhesion force of ECV304 at two and five hours of cultivation was significantly high and matched their FAK activation level. In comparison, ECV304 on FN-coated membrane had higher and more stable cell adhesion force (0.577–2.053 nN). FN coating intensified the cell adhesion force of ECV304 with culture time and similar outcome was present on the activation level of FAK. Therefore, this study demonstrated a relationship between cell adhesion force and FAK activation level that was dependant on the choice of the extracellular matrix (ECM) component. Subsequently, two tyrosine kinase inhibitors (AG18 and genistein) and one PI3K inhibitor (LY294002) were applied to study the influence of protein phosphorylation on the cell adhesion force. FAK plays an important role on cell attachment and DEP force measurement is a useful technique for studying cell adhesion. PMID:22778624

  19. Quantitative measurement of changes in adhesion force involving focal adhesion kinase during cell attachment, spread, and migration

    SciTech Connect

    Wu, C.-C.; Su, H.-W.; Lee, C.-C.; Tang, M.-J.; Su, F.-C. . E-mail: fcsu@mail.ncku.edu.tw

    2005-04-01

    Focal adhesion kinase (FAK) is a critical protein for the regulation of integrin-mediated cellular functions and it can enhance cell motility in Madin-Darby canine kidney (MDCK) cells by hepatocyte growth factor (HGF) induction. We utilized optical trapping and cytodetachment techniques to measure the adhesion force between pico-Newton and nano-Newton (nN) for quantitatively investigating the effects of FAK on adhesion force during initial binding (5 s), beginning of spreading (30 min), spreadout (12 h), and migration (induced by HGF) in MDCK cells with overexpressed FAK (FAK-WT), FAK-related non-kinase (FRNK), as well as normal control cells. Optical tweezers was used to measure the initial binding force between a trapped cell and glass coverslide or between a trapped bead and a seeded cell. In cytodetachment, the commercial atomic force microscope probe with an appropriate spring constant was used as a cyto-detacher to evaluate the change of adhesion force between different FAK expression levels of cells in spreading, spreadout, and migrating status. The results demonstrated that FAK-WT significantly increased the adhesion forces as compared to FRNK cells throughout all the different stages of cell adhesion. For cells in HGF-induced migration, the adhesion force decreased to almost the same level ({approx}600 nN) regardless of FAK levels indicating that FAK facilitates cells to undergo migration by reducing the adhesion force. Our results suggest FAK plays a role of enhancing cell adhesive ability in the binding and spreading, but an appropriate level of adhesion force is required for HGF-induced cell migration.

  20. Molecular markers of cell adhesion in ameloblastomas. An update.

    PubMed

    González-González, Rogelio; Molina-Frechero, Nelly; Damian-Matsumura, Pablo; Bologna-Molina, Ronell

    2014-01-01

    Ameloblastoma is the most common odontogenic tumor of epithelial origin, and though it is of a benign nature, it frequently infiltrates the bone, has a high rate of recurrence and could potentially become malignant. Cellular adhesion potentially plays an important role in the manifestation of these characteristics and in the tumor biology of ameloblastomas. Losses of cell-cell and extracellular matrix adhesion and cohesion are among the first events that occur in the invasion and growth of tumors of epithelial origin. The present review includes a description of the molecules that are involved in cell adhesion as reported for various types of ameloblastomas and discusses the possible roles of these molecules in the biological behaviors of this odontogenic tumor. Knowledge of the complex mechanisms in which these molecules play a role is critical for the research and discovery of future therapeutic targets.

  1. Actin filaments regulate the adhesion between the plasma membrane and the cell wall of tobacco guard cells.

    PubMed

    Yu, Qin; Ren, Jing-Jing; Kong, Lan-Jing; Wang, Xiu-Ling

    2017-08-13

    During the opening and closing of stomata, guard cells undergo rapid and reversible changes in their volume and shape, which affects the adhesion of the plasma membrane (PM) to the cell wall (CW). The dynamics of actin filaments in guard cells are involved in stomatal movement by regulating structural changes and intracellular signaling. However, it is unclear whether actin dynamics regulate the adhesion of the PM to the CW. In this study, we investigated the relationship between actin dynamics and PM-CW adhesion by the hyperosmotic-induced plasmolysis of tobacco guard cells. We found that actin filaments in guard cells were depolymerized during mannitol-induced plasmolysis. The inhibition of actin dynamics by treatment with latrunculin B or jasplakinolide and the disruption of the adhesion between the PM and the CW by treatment with RGDS peptide (Arg-Gly-Asp-Ser) enhanced guard cell plasmolysis. However, treatment with latrunculin B alleviated the RGDS peptide-induced plasmolysis and endocytosis. Our results reveal that the actin depolymerization is involved in the regulation of the PW-CW adhesion during hyperosmotic-induced plasmolysis in tobacco guard cells.

  2. Effect of pretreatment with mildly acidic hypochlorous acid on adhesion to caries-affected dentin using a self-etch adhesive.

    PubMed

    Kunawarote, Sitthikorn; Nakajima, Masatoshi; Foxton, Richard M; Tagami, Junji

    2011-02-01

    Caries-affected dentin is covered with a thicker and organically enriched smear layer than normal dentin. This may affect the demineralization ability and the infiltration of self-etch adhesives, thus reducing the efficacy of bonding to caries-affected dentin. This study evaluated the adhesion of a two-step self-etching adhesive to normal and caries-affected dentin after pretreatment with mildly acidic hypochlorous acid (HOCl) solutions. We used a microtensile bond strength (μTBS) test to compare the μTBS of Clearfil SE Bond to either caries-affected dentin or to normal dentin, after pretreatment for 5 s with one of three solutions (806 mM NaOCl, or 0.95 or 1.91 mM HOCl). The μTBS of the self-etch adhesive was significantly lower to caries-affected dentin than to normal dentin. Pretreatment with 0.95 mM HOCl improved the μTBS of the self-etch adhesive to caries-affected dentin, but there was no significant difference compared with normal dentin. On the other hand, pretreatment with 806 mM NaOCl or 1.91 mM HOCl did not demonstrate a significant improvement in the μTBS to caries-affected dentin. None of the pretreatments demonstrated a negative effect on adhesion to normal dentin.

  3. Single and collective cell migration: the mechanics of adhesions

    PubMed Central

    De Pascalis, Chiara; Etienne-Manneville, Sandrine

    2017-01-01

    Chemical and physical properties of the environment control cell proliferation, differentiation, or apoptosis in the long term. However, to be able to move and migrate through a complex three-dimensional environment, cells must quickly adapt in the short term to the physical properties of their surroundings. Interactions with the extracellular matrix (ECM) occur through focal adhesions or hemidesmosomes via the engagement of integrins with fibrillar ECM proteins. Cells also interact with their neighbors, and this involves various types of intercellular adhesive structures such as tight junctions, cadherin-based adherens junctions, and desmosomes. Mechanobiology studies have shown that cell–ECM and cell–cell adhesions participate in mechanosensing to transduce mechanical cues into biochemical signals and conversely are responsible for the transmission of intracellular forces to the extracellular environment. As they migrate, cells use these adhesive structures to probe their surroundings, adapt their mechanical properties, and exert the appropriate forces required for their movements. The focus of this review is to give an overview of recent developments showing the bidirectional relationship between the physical properties of the environment and the cell mechanical responses during single and collective cell migration. PMID:28684609

  4. Effect of surface potential on epithelial cell adhesion, proliferation and morphology.

    PubMed

    Chang, Hsun-Yun; Kao, Wei-Lun; You, Yun-Wen; Chu, Yi-Hsuan; Chu, Kuo-Jui; Chen, Peng-Jen; Wu, Chen-Yi; Lee, Yu-Hsuan; Shyue, Jing-Jong

    2016-05-01

    Cell adhesion is the basis of individual cell survival, division and motility. Hence, understanding the effects that the surface properties have on cell adhesion, proliferation and morphology are crucial. In particular, surface charge/potential has been identified as an important factor that affects cell behavior. However, how cells respond to incremental changes in surface potential remains unclear. By using binary self-assembled monolayer (SAM) modified Au surfaces that are similar in mechanical/chemical properties and provide a series of surface potentials, the effect of surface potential on the behavior of cells can be studied. In this work, the effect of surface potential on epithelial cells, including human embryonic kidney (HEK293T) and human hepatocellular carcinoma (HepG2), were examined. The results showed that the adhesion density of epithelial cells increased with increasing surface potential, which is similar to but varied more significantly compared with fibroblasts. The proliferation rate is found to be independent of surface potential in both cell types. Furthermore, epithelial cells show no morphological change with respect to surface potential, whereas the morphology of the fibroblasts clearly changed with the surface potential. These differences between the cell types were rationalized by considering the difference in extracellular matrix composition. Laminin-dominant epithelial cells showed higher adhesion density and less morphological change than did fibronectin-dominant fibroblasts because the more significant adsorption of positively charged laminin on the surface enhanced the adhesion of epithelial cells. In contrast, due to the dominance of negatively charged fibronectin that adsorbed weakly on the surface, fibroblasts had to change their morphology to fit the inhomogeneous fibronectin-adsorbed area.

  5. Relationship between neuronal migration and cell-substratum adhesion: laminin and merosin promote olfactory neuronal migration but are anti- adhesive

    PubMed Central

    1991-01-01

    Regulation by the extracellular matrix (ECM) of migration, motility, and adhesion of olfactory neurons and their precursors was studied in vitro. Neuronal cells of the embryonic olfactory epithelium (OE), which undergo extensive migration in the central nervous system during normal development, were shown to be highly migratory in culture as well. Migration of OE neuronal cells was strongly dependent on substratum- bound ECM molecules, being specifically stimulated and guided by laminin (or the laminin-related molecule merosin) in preference to fibronectin, type I collagen, or type IV collagen. Motility of OE neuronal cells, examined by time-lapse video microscopy, was high on laminin-containing substrata, but negligible on fibronectin substrata. Quantitative assays of adhesion of OE neuronal cells to substrata treated with different ECM molecules demonstrated no correlation, either positive or negative, between the migratory preferences of cells and the strength of cell-substratum adhesion. Moreover, measurements of cell adhesion to substrata containing combinations of ECM proteins revealed that laminin and merosin are anti-adhesive for OE neuronal cells, i.e., cause these cells to adhere poorly to substrata that would otherwise be strongly adhesive. The evidence suggests that the anti- adhesive effect of laminin is not the result of interactions between laminin and other ECM molecules, but rather an effect of laminin on cells, which alters the way in which cells adhere. Consistent with this view, laminin was found to interfere strongly with the formation of focal contacts by OE neuronal cells. PMID:1918163

  6. Prolactin stimulates integrin-mediated adhesion of circulating mononuclear cells to endothelial cells.

    PubMed

    Montes de Oca, Pável; Macotela, Yazmín; Nava, Gabriel; López-Barrera, Fernando; de la Escalera, Gonzalo Martínez; Clapp, Carmen

    2005-05-01

    Attachment of leukocytes to endothelial cells is an essential step for the extravasation and recruitment of cells at sites of inflammation. The pituitary hormone prolactin (PRL) is involved in the inflammatory process. Here, we show that treatment with PRL of human peripheral blood mononuclear cells (PBMC) stimulates their adhesion to human umbilical vein endothelial cells (HUVEC) activated by interleukin-1beta. Stimulation of adhesion by PRL is mediated via integrins leukocyte functional antigen-1 (LFA-1) and very late antigen-4 (VLA-4), because immunoneutralization of both integrins prevents PRL action. Also, PRL promotes the adhesion of PBMC to immobilized intercellular adhesion molecule-1 and fibronectin, ligands for LFA-1 and VLA-4, respectively. Stimulation of integrin-mediated cell adhesion by PRL may involve the activation of chemokine receptors, because PRL upregulates the expression of the G-protein-coupled chemokine receptor CXCR3 in PBMC, and pertussis toxin, a specific G-protein inhibitor, blocks PRL stimulation of PBMC adhesion to HUVEC. In addition, PRL stimulates tyrosine phosphorylation pathways leading to leukocyte adhesion. PRL triggered the tyrosine phosphorylation of Janus kinase-2, of signal transducer and activator of transcription-3 and 5, and of the focal adhesion protein paxillin. Furthermore, genistein, a tyrosine kinase inhibitor, blocked PRL-stimulated adhesion of PBMC and Jurkat T-cells to HUVEC. These results suggest that PRL promotes integrin-mediated leukocyte adhesion to endothelial cells via chemokine receptors and tyrosine phosphorylation signaling pathways.

  7. Adhesion between peptides/antibodies and breast cancer cells

    NASA Astrophysics Data System (ADS)

    Meng, J.; Paetzell, E.; Bogorad, A.; Soboyejo, W. O.

    2010-06-01

    Atomic force microscopy (AFM) techniques were used to measure the adhesion forces between the receptors on breast cancer cells specific to human luteinizing hormone-releasing hormone (LHRH) peptides and antibodies specific to the EphA2 receptor. The adhesion forces between LHRH-coated AFM tips and human MDA-MB-231 cells (breast cancer cells) were shown to be about five times greater than those between LHRH-coated AFM tips and normal Hs578Bst breast cells. Similarly, those between EphA2 antibody-coated AFM tips and breast cancer cells were over five times greater than those between EphA2 antibody-coated AFM tips and normal breast cells. The results suggest that AFM can be used for the detection of breast cancer cells in biopsies. The implications of the results are also discussed for the early detection and localized treatment of cancer.

  8. Tensile bond strength and SEM evaluation of caries-affected dentin using dentin adhesives.

    PubMed

    Nakajima, M; Sano, H; Burrow, M F; Tagami, J; Yoshiyama, M; Ebisu, S; Ciucchi, B; Russell, C M; Pashley, D H

    1995-10-01

    Tensile bond strength measurements are commonly used for the evaluation of dentin adhesive systems. Most tests are performed using extracted non-carious human or bovine dentin. However, the adhesion of resins to caries-affected dentin is still unclear. The objectives of this study were to test the hypothesis that bonding to caries-affected dentin is inferior to bonding to normal dentin, and that the quality of the hybrid layer plays a major role in creating good adhesion. We used a micro-tensile bond strength test to compare test bond strengths made to either caries-affected dentin or normal dentin, using three commercial adhesive systems (All Bond 2, Scotchbond Multi-Purpose, and Clearfil Liner Bond II). For scanning electron microscopy, the polished interfaces between the adhesive bond and dentin were subjected to brief exposure to 10% phosphoric acid solution and 5% sodium hypochlorite, so that the quality of the hybrid layers could be observed. Bonding to normal dentin with either All Bond 2 (26.9 +/- 8.8 MPa) or Clearfil Liner Bond II (29.5 +/- 10.9 MPa) showed tensile bond strengths higher than those to caries-affected dentin (13.0 +/- 3.6 MPa and 14.0 +/- 4.3 MPa, respectively). The tensile bond strengths obtained with Scotchbond Multi-Purpose were similar in normal and caries-affected dentin (20.3 +/- 5.5 MPa and 18.5 +/- 4.0 MPa, respectively). The hybrid layers created by All Bond 2 in normal dentin and by Clearfil Liner Bond II in normal or caries-affected dentin showed phosphoric acid and sodium hypochlorite resistance, whereas the hybrid layers created by All Bond 2 in caries-affected dentin and those created by Scotchbond Multi-Purpose to normal and caries-affected dentin showed partial susceptibility to the acid and sodium hypochlorite treatment. The results indicate that the strength of adhesion to dentin depends upon both the adhesive system used and the type of dentin. Moreover, the quality of the hybrid layer may not always contribute

  9. Ethanol exposure disrupts extraembryonic microtubule cytoskeleton and embryonic blastomere cell adhesion, producing epiboly and gastrulation defects

    PubMed Central

    Sarmah, Swapnalee; Muralidharan, Pooja; Curtis, Courtney L.; McClintick, Jeanette N.; Buente, Bryce B.; Holdgrafer, David J.; Ogbeifun, Osato; Olorungbounmi, Opeyemi C.; Patino, Liliana; Lucas, Ryan; Gilbert, Sonya; Groninger, Evan S.; Arciero, Julia; Edenberg, Howard J.; Marrs, James A.

    2013-01-01

    Summary Fetal alcohol spectrum disorder (FASD) occurs when pregnant mothers consume alcohol, causing embryonic ethanol exposure and characteristic birth defects that include craniofacial, neural and cardiac defects. Gastrulation is a particularly sensitive developmental stage for teratogen exposure, and zebrafish is an outstanding model to study gastrulation and FASD. Epiboly (spreading blastomere cells over the yolk cell), prechordal plate migration and convergence/extension cell movements are sensitive to early ethanol exposure. Here, experiments are presented that characterize mechanisms of ethanol toxicity on epiboly and gastrulation. Epiboly mechanisms include blastomere radial intercalation cell movements and yolk cell microtubule cytoskeleton pulling the embryo to the vegetal pole. Both of these processes were disrupted by ethanol exposure. Ethanol effects on cell migration also indicated that cell adhesion was affected, which was confirmed by cell aggregation assays. E-cadherin cell adhesion molecule expression was not affected by ethanol exposure, but E-cadherin distribution, which controls epiboly and gastrulation, was changed. E-cadherin was redistributed into cytoplasmic aggregates in blastomeres and dramatically redistributed in the extraembryonic yolk cell. Gene expression microarray analysis was used to identify potential causative factors for early development defects, and expression of the cell adhesion molecule protocadherin-18a (pcdh18a), which controls epiboly, was significantly reduced in ethanol exposed embryos. Injecting pcdh18a synthetic mRNA in ethanol treated embryos partially rescued epiboly cell movements, including enveloping layer cell shape changes. Together, data show that epiboly and gastrulation defects induced by ethanol are multifactorial, and include yolk cell (extraembryonic tissue) microtubule cytoskeleton disruption and blastomere adhesion defects, in part caused by reduced pcdh18a expression. PMID:24167711

  10. Thermodynamics of short-term cell adhesion in vitro.

    PubMed Central

    Vogler, E A

    1988-01-01

    A thermodynamic theory of short-term (less than 2 hr) in vitro cell adhesion has been developed which allows calculation of reversible work of adhesion and estimation of a term proportional to cell-substrate contact area. The theory provides a means of determining a parameter related to membrane wetting tension for microscopic cells that does not require special manipulations which might desiccate or denature delicate cell membranes. Semiquantitative agreement between predicted and experimentally-measured cell adhesion obtained for three different cell types (MDCK, RBL-1, and HCT-15) in two different liquid phase compositions of surfactants (Tween-80 and fetal bovine serum) supports concepts and approximations utilized in development of theory. Cell-substrate contact areas were largest for wettable surfaces treated with ionizing corona or plasma discharges and smallest for hydrophobic materials for each cell type studied. Contact area for the continuous dog-kidney cell line MDCK was larger than that of either the leukemic blood cell RBL-1 or the anaplastic human colon cell HCT-15. PMID:3390519

  11. Bonding of simplified adhesive systems to caries-affected dentin of primary teeth.

    PubMed

    Alves, Fabiana Bucholdz; Lenzi, Tathiane Larissa; Reis, Alessandra; Loguercio, Alessandro D; Carvalho, Thiago Saads; Raggio, Daniela Prócida

    2013-10-01

    To evaluate the bonding of simplified adhesive systems to sound and caries-affected dentin of primary teeth with microtensile (µTBS) and nanoleakage (NL) tests. Occlusal cavities were prepared in 36 sound second primary molars. Half of the specimens were submitted to pH cycling to simulate caries-affected dentin. Teeth were randomly restored with one of three materials: the etch-and-rinse adhesive system Adper Single Bond 2 (SB), the two-step self-etching adhesive system Adper SE Plus (SE), and the one-step self-etching adhesive system Adper Easy One (EASY). After storage for 24 h, specimens with cross-sectional areas of 0.8 mm2 were prepared for microtensile testing (1 mm/min). One stick from each tooth was immersed in silver nitrate solution (24 h) and allowed to develop for 8 h in order to score the nano leakage with SEM. The fracture pattern was evaluated using a stereomicroscope (400X). The µTBS means were analyzed by two-way ANOVA and Tukey's post-hoc test. For NL, the Kruskal- Wallis and Mann-Whitney tests were used (α < 0.05). SB (35.5 ± 3.5) showed the highest µTBS value to sound dentin, followed by EASY (26.3 ± 1.9) and SE (18.2 ± 6.5) (p < 0.05). No difference among materials was observed for caries-affected dentin (SB: 17.8 ± 4.2; SE: 13.9 ± 3.2; EASY: 14.4 ± 4.2, p > 0.05). For all groups, adhesive/mixed fracture prevailed. Caries affected dentin promoted silver nitrate uptake into the adhesive interface; however, with SE, the nano leakage was more pronounced than in the other adhesive systems, even in sound dentin. Caries-affected dentin negatively influences the bond strength and nano leakage of the two-step etch-and-rinse and one-step self-etching adhesive systems tested in primary teeth.

  12. Prior exposure of endothelial cells to hydroxycarbamide alters the flow dynamics and adhesion of sickle red blood cells.

    PubMed

    Verger, Emmanuelle; Schoëvaërt, Damien; Carrivain, Pascal; Victor, Jean-Marc; Lapouméroulie, Claudine; Elion, Jacques

    2014-01-01

    The hallmark of sickle cell disease (SCD) is vasoocclusive crisis (VOC). The sickle red blood cells (SS-RBCs) present enhanced adhesion to activated endothelial cells (ECs) as compared to normal RBCs (AA-RBCs) and believed to contribute to VOC. Hydroxycarbamide (HC), the sole drug thus far proven as efficacious at reducing VOC frequency, alters the expression of adhesion proteins both on RBCs and ECs. We investigated the functional effect of HC on the adhesive properties of ECs from the micro- or the macrocirculation (TrHBMEC, HPMEC, and HUVEC). Using a flow chamber, we analyzed RBC dynamics on the treated or untreated EC bed and firm adhesion in basal and inflammatory conditions. Most significant effects were obtained with ECs from the pulmonary microcirculation (HPMEC). HC treatment of ECs affects both transient interactions and firm adhesion of SS-RBCs to the EC bed. Indeed, first, HC-treatment of ECs decreases the number of firmly adherent SS-RBCs to the adhesion level of AA-RBCs in a VCAM-1 independent manner. Second, HC significantly increases the mean velocity of SS-RBCs and reduces the population of SS-RBCs in contact with the EC bed. These data provide additional evidence that modulation of SS-RBCs/ECs interactions by HC represents an important aspect of its mechanism of action.

  13. Cell adhesion on poly(propylene fumarate-co-ethylene glycol) hydrogels.

    PubMed

    Tanahashi, Kazuhiro; Mikos, Antonios G

    2002-12-15

    We synthesized poly(propylene fumarate-co-ethylene glycol) block copolymers [P(PF-co-EG)] that were crosslinked to form hydrogels and investigated the effect of copolymer composition on cell adhesion to the hydrogels. These copolymers were water soluble when the molar ratio of ethylene glycol repeating unit to propylene fumarate repeating unit was higher than 4.4. The water content of swollen hydrogels increased from 29 to 63% and the water contact angle decreased from 38 to 21 degrees as the molar ratio increased from 0.6 to 4.4. No significant change in either property was observed for ratios higher than 4.4. In a cell adhesion assay under serum-free conditions, the number of adherent platelets and smooth muscle cells decreased from 21 to 2% and from 78 to 20% of the initial seeding density, respectively, as the molar ratio increased from 0.6 to 7.8. Adherent smooth muscle cells did not spread on the hydrogels of the compositions tested. Adherent platelets did not show any filopodia. These results suggest that the hydrophilicity of P(PF-co-EG) hydrogels is one of the factors affecting cell adhesion, and that copolymer modification may be required for enhancing cell adhesion for an application involving the copolymers as in situ crosslinkable cell carriers.

  14. ZF21 protein regulates cell adhesion and motility.

    PubMed

    Nagano, Makoto; Hoshino, Daisuke; Sakamoto, Takeharu; Kawasaki, Noritaka; Koshikawa, Naohiko; Seiki, Motoharu

    2010-07-02

    Cell migration on an extracellular matrix (ECM) requires continuous formation and turnover of focal adhesions (FAs) along the direction of cell movement. However, our knowledge of the components of FAs and the mechanism of their regulation remains limited. Here, we identify ZF21, a member of a protein family characterized by the presence of a phosphatidylinositol 3-phosphate-binding FYVE domain, to be a new regulator of FAs and cell movement. Knockdown of ZF21 expression in cells increased the number of FAs and suppressed cell migration. Knockdown of ZF21 expression also led to a significant delay in FA disassembly following induction of synchronous disassembly of FAs by nocodazole treatment. ZF21 bound to focal adhesion kinase, localized to FAs, and was necessary for dephosphorylation of FAK at Tyr(397), which is important for disassembly of FAs. Thus, ZF21 represents a new component of FAs, mediates disassembly of FAs, and thereby regulates cell motility.

  15. Bonding Performance of a Multimode Adhesive to Artificially-induced Caries-affected Primary Dentin.

    PubMed

    Lenzi, Tathiane Larissa; Raggio, Daniela Prócida; Soares, Fabio Zovico Maxnuck; Rocha, Rachel de Oliveira

    2015-04-01

    To investigate the bonding of a new universal adhesive applied using different etching strategies on sound and caries-affected dentin of primary teeth. Flat dentin surfaces from 50 primary molars were randomly assigned to 10 groups according to substrate (sound dentin [SD] vs caries-affected dentin [CAD] pH cycled for 14 days) and bonding approach (Scotchbond Universal Adhesive: self-etching, vs dry or wet-bonding etch-and-rinse strategies; Adper Single Bond Plus [two-step etch-and-rinse adhesive] and Clearfil SE Bond [two-step self-etching system] as controls). After 24 h of water storage, bonded sticks with cross-sectional areas of 0.8 mm2 were tested for microtensile bond strength (μTBS). Two sticks from each tooth were immersed in silver nitrate solution in order to evaluate nanoleakage (NL) with SEM. The μTBS means were analyzed using two-way ANOVA and Tukey's tests. For NL, the Kruskal-Wallis and Mann-Whitney tests were used (α = 0.05). The influence of the etching strategy on the bonding performance of the universal adhesive was substrate dependent. The self-etching approach resulted in lower μTBS values and higher silver nitrate uptake into hybrid layers for Scotchbond Universal Adhesive on SD, while no difference among experimental groups was observed in CAD. It is preferable to use the universal adhesive following either a dry- or wet-bonding etch-and-rinse approach on both sound and caries-affected primary dentin.

  16. How to let go: pectin and plant cell adhesion.

    PubMed

    Daher, Firas Bou; Braybrook, Siobhan A

    2015-01-01

    Plant cells do not, in general, migrate. They maintain a fixed position relative to their neighbors, intimately linked through growth and differentiation. The mediator of this connection, the pectin-rich middle lamella, is deposited during cell division and maintained throughout the cell's life to protect tissue integrity. The maintenance of adhesion requires cell wall modification and is dependent on the actin cytoskeleton. There are developmental processes that require cell separation, such as organ abscission, dehiscence, and ripening. In these instances, the pectin-rich middle lamella must be actively altered to allow cell separation, a process which also requires cell wall modification. In this review, we will focus on the role of pectin and its modification in cell adhesion and separation. Recent insights gained in pectin gel mechanics will be discussed in relation to existing knowledge of pectin chemistry as it relates to cell adhesion. As a whole, we hope to begin defining the physical mechanisms behind a cells' ability to hang on, and how it lets go.

  17. Numerical analysis of cell adhesion in capillary flow

    NASA Astrophysics Data System (ADS)

    Takeishi, Naoki; Imai, Yohsuke; Ishida, Shunichi; Omori, Toshihiro; Kamm, Roger; Ishikawa, Takuji

    2016-11-01

    Numerical simulation of cell adhesion was performed for capillaries whose diameter is comparable to or smaller than that of the cell. Despite a lot of works about leukocyte and tumor cell rolling, cell motion in capillaries has remained unclear. The solid and fluid mechanics of a cell in flow was coupled with a slip bond model of ligand-receptor interactions. When the size of a capillary was reduced, the cell always transitioned to "bullet-like" motion, with a consequent decrease in the velocity of the cell. A state diagram is obtained for various values of capillary diameter and receptor density. According to our numerical results, bullet motion enables firm adhesion of a cell to the capillary wall even for a weak ligand-receptor binding. We also quantified effects of various parameters, including the dissociation rate constant, the spring constant, and the reactive compliance on the characteristics of cell motion. Our results suggest that even under the interaction between PSGL-1 and P-selectin, which is mainly responsible for leukocyte rolling, a cell is able to show firm adhesion in a small capillary. These findings may help in understanding such phenomena as leukocyte plugging and cancer metastasis. This research was supported by JSPS KAKENHI Grant Numbers 25000008, 26107703, 14J03967. We also acknowledge support from the Tohoku University Division for International Advanced Research and Education Organization.

  18. Effect of oligosaccharides on the adhesion of gut bacteria to human HT-29 cells.

    PubMed

    Altamimi, M; Abdelhay, O; Rastall, R A

    2016-06-01

    The influence of five oligosaccharides (cellobiose, stachyose, raffinose, lactulose and chito-oligosaccharides) on the adhesion of eight gut bacteria (Bifidobacterium bifidum ATCC 29521, Bacteroides thetaiotaomicron ATCC 29148D-5, Clostridium leptum ATCC 29065, Blautia coccoides ATCC 29236, Faecalibacterium prausnitzii ATCC 27766, Bacteroides fragilis ATCC 23745, Clostridium difficile ATCC 43255 and Lactobacillus casei ATCC 393) to mucous secreting and non-mucous secreting HT-29 human epithelial cells, was investigated. In pure culture, the bacteria showed variations in their ability to adhere to epithelial cells. The effect of oligosaccharides diminished adhesion and the presence of mucus played a major factor in adhesion, likely due to high adhesiveness to mucins present in the native human mucus layer covering the whole cell surface. However, clostridia displayed almost the same level of adhesion either with or without mucus being present. Bl. coccoides adhesion was decreased by stachyose and cellobiose in non-mucus-secreting cells in pure culture, while in mixed faecal culture cellobiose displayed the highest antiadhesive activity with an overall average of 65% inhibition amongst tested oligomers and lactulose displayed the lowest with an average of 47.4%. Bifidobacteria, Bacteroides, lactobacilli and clostridia were inhibited within the following ranges 47-78%, 32-65%, 11.7-58% and 64-85% respectively. This means that clostridia were the most strongly influenced members of the microflora amongst the bacterial groups tested in mixed culture. In conclusion, introducing oligosaccharides which are candidate prebiotics into pure or mixed cultures has affected bacterial adhesion. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Modulation of endogenous Cysteine Protease Inhibitor (ICP) 1 expression in Entamoeba histolytica affects amoebic adhesion to Extracellular Matrix proteins.

    PubMed

    Lee, Young Ah; Saito-Nakano, Yumiko; Kim, Kyeong Ah; Min, Arim; Nozaki, Tomoyoshi; Shin, Myeong Heon

    2015-02-01

    Entamoeba histolytica is an enteric tissue-invading protozoan parasite that causes amoebic colitis and occasionally liver abscess in humans. During tissue invasion, amoebic adhesion to host components is an important event for host cell death leading to successful invasion and infection. Among amoebic virulence factors, Gal/GalNAc lectin is known to be major adhesion factor to host cells. In this study, we investigated the role of amoebic secreted CP (Cysteine Proteases) in amoebic adhesion to extracellular matrix (ECM) protein using CP inhibitor and E. histolytica strains in which the endogenous inhibitor of cysteine protease (ICP) 1 gene was overexpressed (ICP1(+)) or repressed by antisense small RNA-mediated gene silencing (ICP1(-)). We found that pretreatment of wild-type amoebae with CP inhibitor E64, or thiol-group modifiers such as diamide and N-Ethylmaleimide resulted in a significant decrease in adhesion to laminin and collagen ECM proteins. Furthermore, ICP1(+) strain, with a reduction of secreted CP activity, exhibited reduced ability by 40% to adhere to laminin. In contrast, ICP1(-) strain, with a 1.9-fold increase of secreted CP activity, showed a two-fold increase in amoebic adherence to laminin compared to the control strain. In addition, total amount of secreted CP5 was decreased in ICP1(+) amoeba. Conversely, total amount of secreted CP1 and mature-form CP5 were increased in ICP1(-) amoeba. We also found that ICP1 was secreted into extracellular milieu. These results suggest that secreted CP activity by E. histolytica may be an important factor affecting adhesion to host proteins, and regulation of CP secretion by ICP plays a major role in pathogenesis. This study provides insight into the CP-mediated tissue pathogenesis in amoeba-invaded lesions during human amoebiasis.

  20. Multiparticle adhesive dynamics. Interactions between stably rolling cells.

    PubMed Central

    King, M R; Hammer, D A

    2001-01-01

    A novel numerical simulation of adhesive particles (cells) reversibly interacting with an adhesive surface under flow is presented. Particle--particle and particle--wall hydrodynamic interactions in low Reynolds number Couette flow are calculated using a boundary element method that solves an integral representation of the Stokes equation. Molecular bonds between surfaces are modeled as linear springs and stochastically formed and broken according to postulated descriptions of force-dependent kinetics. The resulting simulation, Multiparticle Adhesive Dynamics, is applied to the problem of selectin-mediated rolling of hard spheres coated with leukocyte adhesion molecules (cell-free system). Simulation results are compared to flow chamber experiments performed with carbohydrate-coated spherical beads rolling on P-selectin. Good agreement is found between theory and experiment, with the main observation being a decrease in rolling velocity with increasing concentration of rolling cells or increasing proximity between rolling cells. Pause times are found to increase and deviation motion is found to decrease as pairs of rolling cells become closer together or align with the flow. PMID:11463626

  1. Alterations in soluble intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in hemodialysis patients.

    PubMed

    Rabb, H; Calderon, E; Bittle, P A; Ramirez, G

    1996-02-01

    Hemodialysis (HD) patients can develop acute reactions during treatment as well as increased long-term susceptibility to infections and malignancies. Abnormalities in leukocyte adhesion may contribute to these processes. Recently, serum levels of soluble adhesion molecules have been detected in circulating blood of normal subjects and in patients with chronic renal failure. We studied the effects of a single dialysis session with new cuprophane membrane on the soluble (s) form of intracellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), two adhesion molecules with a variety of immunologic roles. Significant elevations in both sICAM-1 (523 +/- 61 v 304 +/- 45 [SEM] ng/mL, P < 0.05) and sVCAM-1 (2,055 +/- 270 v 1,189 +/- 149 ng/mL, P < 0.05) were observed in HD patients at baseline compared with controls. Both sICAM-1 and sVCAM-1 levels decreased after a 3-hour HD session (P < 0.001). Early in HD, sICAM-1 levels, though lower than predialysis, were elevated in the exit line of the dialyzer compared with entrance (339 +/- 64 v 259 +/- 53 ng/mL, P < 0.001), whereas sVCAM-1 was decreased on the exit line compared with entrance (639 +/- 90 v 932 +/- 92 ng/mL, P < 0.001). Because ICAM-1 and VCAM-1 are important for many leukocyte functions, alterations in serum levels of sICAM-1 and sVCAM-1 may play a role in the immunologic consequences of uremia and HD treatment.

  2. Pharmacology of the cell/matrix form of adhesion.

    PubMed

    Meldolesi, Jacopo

    2016-05-01

    Cell adhesions are heterogeneous processes including two main forms, CAM and cell/matrix forms. Both these forms induce the interaction among cells and with the extracellular matrix, and the generation of intracellular signals. The signaling of the two adhesion forms include, at the cell surface, involvement of distinct integrins, necessary for intracellular cascade activation. I will focus on the cell/integrin form based on two specific integrins, α5β1 (the most important) and αvβ3, activated by the preferential binding of fibronectin, a unique extracellular matrix protein. Such binding induces local assembly of stratified adhesion complexes containing protein kinases, that trigger the intracellular signaling cascades (Akt, ERK and others); proteins that sustain mechanical processes; and proteins associated with the cytoskeleton. In view of its role in several diseases, from cancers to the eye macular-degeneration; from brain neurodegeneration to fibroses, the pharmacological interest for the cell/integrin adhesion has grown, and presumably will further grow in the near future. The agents identified and developed for therapy include antibodies, many peptides and chemical drugs against α5β1 integrin; drugs against fibronectin and metalloproteinases 2/9, responsible of the latter enzyme proteolysis; anti-kinase and anti-cascade drugs, some of which targeted to the activation of transcription factors and/or their transfer to the nucleus, with repression or activation of gene expression. A new perspective, based on the investigation of both animal models and human patients, includes factors active on the cell/matrix and CAM adhesions, considered separately or coordinately in distinct therapeutic approaches, integrated or not with classical chemotherapic treatments. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. [Curing mode of universal adhesives affects the bond strength of resin cements to dentin].

    PubMed

    Fu, Z R; Tian, F C; Zhang, L; Han, B; Wang, X Y

    2017-02-18

    To determine the effects of curing mode of one-step and two-step universal adhesives on the micro-tensile bond strength (μTBS) of different dual-cure resin cements to dentin. One-step universal adhesive Single Bond Universal (SBU), and two-step universal adhesive OptiBond Versa (VSA) were chosen as the subjects, one-step self-etching adhesive OptiBond All in One (AIO) and two-step self-etching adhesive Clearfil SE Bond (SEB) were control groups, and two dual-cure resin cements RelyX Ultimate (RLX) and Nexus 3 Universal (NX3) were used in this study. In this study, 80 extracted human molars were selected and the dentin surface was exposed using diamond saw. The teeth were divided into 16 groups according to the adhesives (AIO, SBU, SEB, VSA), cure modes of adhesives (light cure, non-light cure) and resin cements (RLX, NX3). The adhesives were applied on the dentin surface following the instruction and whether light cured or not, then the resin cements were applied on the adhesives with 1 mm thickness and light cured (650 mW/cm(2) for 20 s. A resin was built up (5 mm) on the cements and light cured layer by layer. After water storage for 24 h, the specimens were cut into resin-cement-dentin strips with a cross sectional area of 1 mm×1 mm and the μTBS was measured. Regarding one-step universal adhesive (SBU) light cured, the μTBS with RLX [(35.45±7.04) MPa] or NX3 [(26.84±10.39) MPa] were higher than SBU non-light cured with RLX [(17.93±8.93) MPa)] or NX3 [(10.07±5.89) MPa, P<0.001]. Compared with AIO, light-cured SBU combined with RLX presented higher μTBS than AIO group [(35.45±7.04) MPa vs. (24.86±8.42) MPa, P<0.05]. When SBU was not lighted, the μTBS was lower than AIO [(17.93±8.93) MPa vs. (22.28±7.57) MPa, P<0.05]. For two-step universal adhesive (VSA) and control adhesive (SEB), curing mode did not affect the μTBS when used with either RLX or NX3 (25.98-32.24 MPa, P>0.05). Curing mode of one-step universal adhesive may affect the μTBS between

  4. Adhesion of Pancreatic Beta Cells to Biopolymer Films

    PubMed Central

    Williams, S. Janette; Wang, Qun; MacGregor, Ronal R.; Siahaan, Teruna J.; Stehno-Bittel, Lisa; Berkland, Cory

    2009-01-01

    Dramatic reversal of Type 1 diabetes in patients receiving pancreatic islet transplants continues to prompt vigorous research concerning the basic mechanisms underlying patient turnaround. At the most fundamental level, transplanted islets must maintain viability and function in vitro and in vivo and should be protected from host immune rejection. Our previous reports showed enhancement of islet viability and insulin secretion per tissue mass for small islets (<125 µm) as compared to large islets (>125 µm), thus, demonstrating the effect of enhancing the mass transport of islets (i.e. increasing tissue surface area to volume ratio). Here, we report the facile dispersion of rat islets into individual cells that are layered onto the surface of a biopolymer film towards the ultimate goal of improving mass transport in islet tissue. The tightly packed structure of intact islets was disrupted by incubating in calcium-free media resulting in fragmented islets, which were further dispersed into individual or small groups of cells by using a low concentration of papain. The dispersed cells were screened for adhesion to a range of biopolymers and the nature of cell adhesion was characterized for selected groups by quantifying adherent cells, measuring the surface area coverage of the cells, and immunolabeling cells for adhesion proteins interacting with selected biopolymers. Finally, beta cells in suspension were centrifuged to form controlled numbers of cell layers on films for future work determining the mass transport limitations in the adhered tissue constructs. PMID:19353639

  5. Endothelial cell migration on surfaces modified with immobilized adhesive peptides.

    PubMed

    Kouvroukoglou, S; Dee, K C; Bizios, R; McIntire, L V; Zygourakis, K

    2000-09-01

    Endothelial cell (EC) migration has been studied on aminophase surfaces with covalently bound RGDS and YIGSRG cell adhesion peptides. The fluorescent marker dansyl chloride was used to quantify the spatial distribution of the peptides on the modified surfaces. Peptides appeared to be distributed in uniformly dispersed large clusters separated by areas of lower peptide concentrations. We employed digital time-lapse video microscopy and image analysis to monitor EC migration on the modified surfaces and to reconstruct the cell trajectories. The persistent random walk model was then applied to analyze the cell displacement data and compute the mean root square speed, the persistence time, and the random motility coefficient of EC. We also calculated the time-averaged speed of cell locomotion. No differences in the speed of cell locomotion on the various substrates were noted. Immobilization of the cell adhesion peptides (RGDS and YIGSRG), however, significantly increased the persistence of cell movement and, thus, the random motility coefficient. These results suggest that immobilization of cell adhesion peptides on the surface of implantable biomaterials may lead to enhanced endothelization rates.

  6. Differential effects of EGF and amphiregulin on adhesion molecule expression and migration of colon carcinoma cells.

    PubMed

    Solic, N; Davies, D E

    1997-08-01

    Epidermal growth factor (EGF) is a potent morphogen affecting cell shape and motility through regulation of adhesive interactions. We have characterized the morphological effects of EGF on GP2d and GP5d colon carcinoma cell lines and have compared the ability of the heparin-binding EGF receptor ligand amphiregulin (AR) to elicit the same effects. EGF induced a marked epithelial-mesenchymal transition in both cell lines. This effect was evident at 7 pM EGF and was associated with a reduction in cellular adherens junctions and diminished cell-cell contact; it was also associated with an increase in expression of alpha2-integrin as well as enhanced adhesion to the substratum and cell spreading. These changes in adhesion molecule expression were accompanied by enhanced migration on collagen. Blockade of cell growth with mitomycin C did not prevent the EGF-induced morphological change, showing that the mitogenic and morphogenic responses of the GP cells were separable. The phosphatidyl inositol (PI) 3-kinase inhibitor wortmannin inhibited basal proliferation but had no effect on the EGF-induced morphological change, further suggesting that the PI 3-kinase pathway was not involved in the morphogenic response of these cells. Amphiregulin stimulated proliferation of both cell lines, but could only elicit a modest morphological change if used at considerably higher doses or if growth was blocked with mitomycin C. In cells treated with 55 nM AR, alpha2-integrin expression was slightly increased; however, unlike the EGF case, adherens junctions remained intact. These differences in the ability of EGF and amphiregulin to affect cellular adhesion and migration may be significant factors influencing normal and tumor cell behavior.

  7. Glucocorticoid-induced tumor necrosis factor receptor family-related ligand triggering upregulates vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 and promotes leukocyte adhesion.

    PubMed

    Lacal, Pedro Miguel; Petrillo, Maria Grazia; Ruffini, Federica; Muzi, Alessia; Bianchini, Rodolfo; Ronchetti, Simona; Migliorati, Graziella; Riccardi, Carlo; Graziani, Grazia; Nocentini, Giuseppe

    2013-10-01

    The interaction of glucocorticoid-induced tumor necrosis factor receptor-family related (GITR) protein with its ligand (GITRL) modulates different functions, including immune/inflammatory response. These effects are consequent to intracellular signals activated by both GITR and GITRL. Previous results have suggested that lack of GITR expression in GITR(-/-) mice decreases the number of leukocytes within inflamed tissues. We performed experiments to analyze whether the GITRL/GITR system modulates leukocyte adhesion and extravasation. For that purpose, we first evaluated the capability of murine splenocytes to adhere to endothelial cells (EC). Our results indicated that adhesion of GITR(-/-) splenocytes to EC was reduced as compared with wild-type cells, suggesting that GITR plays a role in adhesion and that this effect may be due to GITRL-GITR interaction. Moreover, adhesion was increased when EC were pretreated with an agonist GITR-Fc fusion protein, thus indicating that triggering of GITRL plays a role in adhesion by EC regulation. In a human in vitro model, the adhesion to human EC of HL-60 cells differentiated toward the monocytic lineage was increased by EC pretreatment with agonist GITR-Fc. Conversely, antagonistic anti-GITR and anti-GITRL Ab decreased adhesion, thus further indicating that GITRL triggering increases the EC capability to support leukocyte adhesion. EC treatment with GITR-Fc favored extravasation, as demonstrated by a transmigration assay. Notably, GITRL triggering increased intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression and anti-ICAM-1 and anti-VCAM-1 Abs reversed GITR-Fc effects. Our study demonstrates that GITRL triggering in EC increases leukocyte adhesion and transmigration, suggesting new anti-inflammatory therapeutic approaches based on inhibition of GITRL-GITR interaction.

  8. YAP regulates cell mechanics by controlling focal adhesion assembly.

    PubMed

    Nardone, Giorgia; Oliver-De La Cruz, Jorge; Vrbsky, Jan; Martini, Cecilia; Pribyl, Jan; Skládal, Petr; Pešl, Martin; Caluori, Guido; Pagliari, Stefania; Martino, Fabiana; Maceckova, Zuzana; Hajduch, Marian; Sanz-Garcia, Andres; Pugno, Nicola Maria; Stokin, Gorazd Bernard; Forte, Giancarlo

    2017-05-15

    Hippo effectors YAP/TAZ act as on-off mechanosensing switches by sensing modifications in extracellular matrix (ECM) composition and mechanics. The regulation of their activity has been described by a hierarchical model in which elements of Hippo pathway are under the control of focal adhesions (FAs). Here we unveil the molecular mechanism by which cell spreading and RhoA GTPase activity control FA formation through YAP to stabilize the anchorage of the actin cytoskeleton to the cell membrane. This mechanism requires YAP co-transcriptional function and involves the activation of genes encoding for integrins and FA docking proteins. Tuning YAP transcriptional activity leads to the modification of cell mechanics, force development and adhesion strength, and determines cell shape, migration and differentiation. These results provide new insights into the mechanism of YAP mechanosensing activity and qualify this Hippo effector as the key determinant of cell mechanics in response to ECM cues.

  9. The MRL proteins: adapting cell adhesion, migration and growth.

    PubMed

    Coló, Georgina P; Lafuente, Esther M; Teixidó, Joaquin

    2012-01-01

    MIG-10, RIAM and Lamellipodin (Lpd) are the founding members of the MRL family of multi-adaptor molecules. These proteins have common domain structures but display distinct functions in cell migration and adhesion, signaling, and in cell growth. The binding of RIAM with active Rap1 and with talin provides these MRL molecules with important regulatory roles on integrin-mediated cell adhesion and migration. Furthermore, RIAM and Lpd can regulate actin dynamics through their binding to actin regulatory Ena/VASP proteins. Recent data generated with the Drosophila MRL ortholog called Pico and with RIAM in melanoma cells indicate that these proteins can also regulate cell growth. As MRL proteins represent a relatively new family, many questions on their structure-function relationships remain unanswered, including regulation of their expression, post-translational modifications, new interactions, involvement in signaling and their knockout mice phenotype.

  10. Quantitative studies of endothelial cell adhesion. Directional remodeling of focal adhesion sites in response to flow forces.

    PubMed Central

    Davies, P F; Robotewskyj, A; Griem, M L

    1994-01-01

    Focal adhesion sites were observed in cultured endothelial cells by tandem scanning confocal microscopy and digitized image analysis, techniques that provide real-time images of adhesion site area and topography in living cells. Image subtraction demonstrated that in the presence of unidirectional steady laminar flow (shear stress [tau] = 10 dyn/cm2) a substantial fraction of focal adhesion sites remodeled in the direction of flow. In contrast, focal adhesions of control (no flow) cells remodeled without preferred direction. In confluent monolayers subjected to shear stresses of 10 dyn/cm2, cells began to realign in the direction of flow after 7-9 h. This was accompanied by redistribution of intracellular stress fibers, alignment of individual focal adhesion sites, and the coalescence of smaller sites resulting in fewer, but larger, focal adhesions per cell. Cell adhesion, repeatedly calculated in the same cells as a function of the areas of focal contact and the separation distances between membrane and substratum, varied by < 10% during both short (30 min), or prolonged (< or = 24 h), periods of exposure to flow. Consistent with these measurements, the gains and losses of focal adhesion area as each site remodeled were approximately equivalent. When the glass substratum was coated with gelatin, rates of remodeling were inhibited by 47% during flow (tau = 10 dyn/cm2). These studies: (a) reveal the dynamic nature of focal adhesion; (b) demonstrate that these sites at the ablumenal endothelial membrane are both acutely and chronically responsive to frictional shear stress forces applied to the opposite (lumenal) cell surface; and (c) suggest that components of the focal adhesion complex may be mechanically responsive elements coupled to the cytoskeleton. Images PMID:8182135

  11. Green tea polyphenol tailors cell adhesivity of RGD displaying surfaces: multicomponent models monitored optically

    NASA Astrophysics Data System (ADS)

    Peter, Beatrix; Farkas, Eniko; Forgacs, Eniko; Saftics, Andras; Kovacs, Boglarka; Kurunczi, Sandor; Szekacs, Inna; Csampai, Antal; Bosze, Szilvia; Horvath, Robert

    2017-02-01

    The interaction of the anti-adhesive coating, poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) and its Arg-Gly-Asp (RGD) functionalized form, PLL-g-PEG-RGD, with the green tea polyphenol, epigallocatechin-gallate (EGCg) was in situ monitored. After, the kinetics of cellular adhesion on the EGCg exposed coatings were recorded in real-time. The employed plate-based waveguide biosensor is applicable to monitor small molecule binding and sensitive to sub-nanometer scale changes in cell membrane position and cell mass distribution; while detecting the signals of thousands of adhering cells. The combination of this remarkable sensitivity and throughput opens up new avenues in testing complicated models of cell-surface interactions. The systematic studies revealed that, despite the reported excellent antifouling properties of the coatings, EGCg strongly interacted with them, and affected their cell adhesivity in a concentration dependent manner. Moreover, the differences between the effects of the fresh and oxidized EGCg solutions were first demonstrated. Using a semiempirical quantumchemical method we showed that EGCg binds to the PEG chains of PLL-g-PEG-RGD and effectively blocks the RGD sites by hydrogen bonds. The calculations supported the experimental finding that the binding is stronger for the oxidative products. Our work lead to a new model of polyphenol action on cell adhesion ligand accessibility and matrix rigidity.

  12. Green tea polyphenol tailors cell adhesivity of RGD displaying surfaces: multicomponent models monitored optically

    PubMed Central

    Peter, Beatrix; Farkas, Eniko; Forgacs, Eniko; Saftics, Andras; Kovacs, Boglarka; Kurunczi, Sandor; Szekacs, Inna; Csampai, Antal; Bosze, Szilvia; Horvath, Robert

    2017-01-01

    The interaction of the anti-adhesive coating, poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) and its Arg-Gly-Asp (RGD) functionalized form, PLL-g-PEG-RGD, with the green tea polyphenol, epigallocatechin-gallate (EGCg) was in situ monitored. After, the kinetics of cellular adhesion on the EGCg exposed coatings were recorded in real-time. The employed plate-based waveguide biosensor is applicable to monitor small molecule binding and sensitive to sub-nanometer scale changes in cell membrane position and cell mass distribution; while detecting the signals of thousands of adhering cells. The combination of this remarkable sensitivity and throughput opens up new avenues in testing complicated models of cell-surface interactions. The systematic studies revealed that, despite the reported excellent antifouling properties of the coatings, EGCg strongly interacted with them, and affected their cell adhesivity in a concentration dependent manner. Moreover, the differences between the effects of the fresh and oxidized EGCg solutions were first demonstrated. Using a semiempirical quantumchemical method we showed that EGCg binds to the PEG chains of PLL-g-PEG-RGD and effectively blocks the RGD sites by hydrogen bonds. The calculations supported the experimental finding that the binding is stronger for the oxidative products. Our work lead to a new model of polyphenol action on cell adhesion ligand accessibility and matrix rigidity. PMID:28186133

  13. Potentialities of ultrasounds for the nondestructive evaluation of cell adhesion.

    PubMed

    Myrdycz, A; Lefebvre, F; Ouaftouh, M; Monchau, F; Callens, D; Hildebrand, H F

    1999-08-01

    The aim of this paper is to present the potentialities of ultrasounds to investigate the mechanical properties of a cell/substrate interface. The adhesion process plays a major role in the development of osteoblastic cells on various substrates used in orthopedic applications such as metals, bioceramics, etc. Particularly, cell adherence appears to be a critical factor in the colonization process. High-frequency and low-power ultrasounds seem to be an appropriate tool for a nondestructive evaluation of interface properties. First, we present the results obtained with bulk longitudinal and shear waves under an arbitrary incidence over an aluminum-adhesive interface. This study was performed for an industrial application of bonding. The results clearly show the sensitivity of shear waves for the evaluation of the adhesion quality owing to the shear solicitations at the interface they induce. A model of ultrasound interactions with a boundary subject to varying degrees of adhesion has been developed and compared to the experiments. Second, we investigated osteoblastic cell cultures with a high-frequency acoustic microscope working at 50 MHz. The images obtained in the shear mode reveal a better contrast than those obtained in the longitudinal mode. For the time being, these results are qualitative, and theoretical models have to be developed according to the point of view of biologists.

  14. Epac Activation Regulates Human Mesenchymal Stem Cells Migration and Adhesion.

    PubMed

    Yu, Jiao-Le; Deng, Ruixia; Chung, Sookja K; Chan, Godfrey Chi-Fung

    2016-04-01

    How to enhance the homing of human mesenchymal stem cells (hMSCs) to the target tissues remains a clinical challenge nowadays. To overcome this barrier, the mechanism responsible for the hMSCs migration and engraftment has to be defined. Currently, the exact mechanism involved in migration and adhesion of hMSCs remains unknown. Exchange protein directly activated by cAMP (Epac), a novel protein discovered in cAMP signaling pathway, may have a potential role in regulating cells adhesion and migration by triggering the downstream Rap family signaling cascades. However, the exact role of Epac in cells homing is elusive. Our study evaluated the role of Epac in the homing of hMSCs. We confirmed that hMSCs expressed functional Epac and its activation enhanced the migration and adhesion of hMSCs significantly. The Epac activation was further found to be contributed directly to the chemotactic responses induced by stromal cell derived factor-1 (SDF-1) which is a known chemokine in regulating hMSCs homing. These findings suggested Epac is connected to the SDF-1 signaling cascades. In conclusion, our study revealed that Epac plays a role in hMSCs homing by promoting adhesion and migration. Appropriate manipulation of Epac may enhance the homing of hMSCs and facilitate their future clinical applications.

  15. Understanding dynamic changes in live cell adhesion with neutron reflectometry

    PubMed Central

    JUNGHANS, ANN; WALTMAN, MARY JO; SMITH, HILLARY L.; POCIVAVSEK, LUKA; ZEBDA, NOUREDDINE; BIRUKOV, KONSTANTIN; VIAPIANO, MARIANO; MAJEWSKI, JAROSLAW

    2015-01-01

    Neutron reflectometry (NR) was used to examine various live cells adhesion to quartz substrates under different environmental conditions, including flow stress. To the best of our knowledge, these measurements represent the first successful visualization and quantization of the interface between live cells and a substrate with sub-nanometer resolution. In our first experiments, we examined live mouse fibroblast cells as opposed to past experiments using supported lipids, proteins, or peptide layers with no associated cells. We continued the NR studies of cell adhesion by investigating endothelial monolayers and glioblastoma cells under dynamic flow conditions. We demonstrated that neutron reflectometry is a powerful tool to study the strength of cellular layer adhesion in living tissues, which is a key factor in understanding the physiology of cell interactions and conditions leading to abnormal or disease circumstances. Continuative measurements, such as investigating changes in tumor cell – surface contact of various glioblastomas, could impact advancements in tumor treatments. In principle, this can help us to identify changes that correlate with tumor invasiveness. Pursuit of these studies can have significant medical impact on the understanding of complex biological problems and their effective treatment, e.g. for the development of targeted anti-invasive therapies. PMID:25705067

  16. Understanding dynamic changes in live cell adhesion with neutron reflectometry

    DOE PAGES

    Junghans, Ann; Waltman, Mary Jo; Smith, Hillary L.; ...

    2014-12-10

    In this study, neutron reflectometry (NR) was used to examine various live cells' adhesion to quartz substrates under different environmental conditions, including flow stress. To the best of our knowledge, these measurements represent the first successful visualization and quantization of the interface between live cells and a substrate with sub-nanometer resolution. In our first experiments, we examined live mouse fibroblast cells as opposed to past experiments using supported lipids, proteins, or peptide layers with no associated cells. We continued the NR studies of cell adhesion by investigating endothelial monolayers and glioblastoma cells under dynamic flow conditions. We demonstrated that neutronmore » reflectometry is a powerful tool to study the strength of cellular layer adhesion in living tissues, which is a key factor in understanding the physiology of cell interactions and conditions leading to abnormal or disease circumstances. Continuative measurements, such as investigating changes in tumor cell — surface contact of various glioblastomas, could impact advancements in tumor treatments. In principle, this can help us to identify changes that correlate with tumor invasiveness. Pursuit of these studies can have significant medical impact on the understanding of complex biological problems and their effective treatment, e.g. for the development of targeted anti-invasive therapies.« less

  17. Understanding dynamic changes in live cell adhesion with neutron reflectometry

    SciTech Connect

    Junghans, Ann; Waltman, Mary Jo; Smith, Hillary L.; Pocivavsek, Luka; Zebda, Noureddine; Birukov, Konstantin; Viapiano, Mariano; Majewski, Jaroslaw

    2014-12-10

    In this study, neutron reflectometry (NR) was used to examine various live cells' adhesion to quartz substrates under different environmental conditions, including flow stress. To the best of our knowledge, these measurements represent the first successful visualization and quantization of the interface between live cells and a substrate with sub-nanometer resolution. In our first experiments, we examined live mouse fibroblast cells as opposed to past experiments using supported lipids, proteins, or peptide layers with no associated cells. We continued the NR studies of cell adhesion by investigating endothelial monolayers and glioblastoma cells under dynamic flow conditions. We demonstrated that neutron reflectometry is a powerful tool to study the strength of cellular layer adhesion in living tissues, which is a key factor in understanding the physiology of cell interactions and conditions leading to abnormal or disease circumstances. Continuative measurements, such as investigating changes in tumor cell — surface contact of various glioblastomas, could impact advancements in tumor treatments. In principle, this can help us to identify changes that correlate with tumor invasiveness. Pursuit of these studies can have significant medical impact on the understanding of complex biological problems and their effective treatment, e.g. for the development of targeted anti-invasive therapies.

  18. How to let go: pectin and plant cell adhesion

    PubMed Central

    Daher, Firas Bou; Braybrook, Siobhan A.

    2015-01-01

    Plant cells do not, in general, migrate. They maintain a fixed position relative to their neighbors, intimately linked through growth and differentiation. The mediator of this connection, the pectin-rich middle lamella, is deposited during cell division and maintained throughout the cell’s life to protect tissue integrity. The maintenance of adhesion requires cell wall modification and is dependent on the actin cytoskeleton. There are developmental processes that require cell separation, such as organ abscission, dehiscence, and ripening. In these instances, the pectin-rich middle lamella must be actively altered to allow cell separation, a process which also requires cell wall modification. In this review, we will focus on the role of pectin and its modification in cell adhesion and separation. Recent insights gained in pectin gel mechanics will be discussed in relation to existing knowledge of pectin chemistry as it relates to cell adhesion. As a whole, we hope to begin defining the physical mechanisms behind a cells’ ability to hang on, and how it lets go. PMID:26236321

  19. Understanding dynamic changes in live cell adhesion with neutron reflectometry

    NASA Astrophysics Data System (ADS)

    Junghans, Ann; Waltman, Mary Jo; Smith, Hillary L.; Pocivavsek, Luka; Zebda, Noureddine; Birukov, Konstantin; Viapiano, Mariano; Majewski, Jaroslaw

    2014-12-01

    Neutron reflectometry (NR) was used to examine various live cells' adhesion to quartz substrates under different environmental conditions, including flow stress. To the best of our knowledge, these measurements represent the first successful visualization and quantization of the interface between live cells and a substrate with sub-nanometer resolution. In our first experiments, we examined live mouse fibroblast cells as opposed to past experiments using supported lipids, proteins, or peptide layers with no associated cells. We continued the NR studies of cell adhesion by investigating endothelial monolayers and glioblastoma cells under dynamic flow conditions. We demonstrated that neutron reflectometry is a powerful tool to study the strength of cellular layer adhesion in living tissues, which is a key factor in understanding the physiology of cell interactions and conditions leading to abnormal or disease circumstances. Continuative measurements, such as investigating changes in tumor cell — surface contact of various glioblastomas, could impact advancements in tumor treatments. In principle, this can help us to identify changes that correlate with tumor invasiveness. Pursuit of these studies can have significant medical impact on the understanding of complex biological problems and their effective treatment, e.g. for the development of targeted anti-invasive therapies.

  20. The cell adhesion molecules Echinoid and Friend of Echinoid coordinate cell adhesion and cell signaling to regulate the fidelity of ommatidial rotation in the Drosophila eye.

    PubMed

    Fetting, Jennifer L; Spencer, Susan A; Wolff, Tanya

    2009-10-01

    Directed cellular movements are a universal feature of morphogenesis in multicellular organisms. Differential adhesion between the stationary and motile cells promotes these cellular movements to effect spatial patterning of cells. A prominent feature of Drosophila eye development is the 90 degrees rotational movement of the multicellular ommatidial precursors within a matrix of stationary cells. We demonstrate that the cell adhesion molecules Echinoid (Ed) and Friend of Echinoid (Fred) act throughout ommatidial rotation to modulate the degree of ommatidial precursor movement. We propose that differential levels of Ed and Fred between stationary and rotating cells at the initiation of rotation create a permissive environment for cell movement, and that uniform levels in these two populations later contribute to stopping the movement. Based on genetic data, we propose that ed and fred impart a second, independent, ;brake-like' contribution to this process via Egfr signaling. Ed and Fred are localized in largely distinct and dynamic patterns throughout rotation. However, ed and fred are required in only a subset of cells - photoreceptors R1, R7 and R6 - for normal rotation, cells that have only recently been linked to a role in planar cell polarity (PCP). This work also provides the first demonstration of a requirement for cone cells in the ommatidial rotation aspect of PCP. ed and fred also genetically interact with the PCP genes, but affect only the degree-of-rotation aspect of the PCP phenotype. Significantly, we demonstrate that at least one PCP protein, Stbm, is required in R7 to control the degree of ommatidial rotation.

  1. Insights into the role of sulfated glycans in cancer cell adhesion and migration through use of branched peptide probe

    PubMed Central

    Brunetti, Jlenia; Depau, Lorenzo; Falciani, Chiara; Gentile, Mariangela; Mandarini, Elisabetta; Riolo, Giulia; Lupetti, Pietro; Pini, Alessandro; Bracci, Luisa

    2016-01-01

    The tetra-branched peptide NT4 selectively binds to different human cancer cells and tissues. NT4 specifically binds to sulfated glycosaminoglycans on cancer cell membranes. Since sulfated glycosaminoglycans are involved in cancer cell interaction with the extracellular matrix, we evaluated the effect of NT4 on cancer cell adhesion and migration. We demonstrated here that the branched peptide NT4 binds sulfated glycosaminoglycans with high affinity and with preferential binding to heparan sulfate. NT4 inhibits cancer cell adhesion and migration on different proteins, without modifying cancer cell morphology or their ability to produce protrusions, but dramatically affecting the directionality and polarity of cell movement. Results obtained by taking advantage of the selective targeting of glycosaminoglycans chains by NT4, provide insights into the role of heparan sulfate proteoglycans in cancer cell adhesion and migration and suggest a determinant role of sulfated glycosaminoglycans in the control of cancer cell directional migration. PMID:27255651

  2. Effect of food models and low-temperature storage on the adhesion of Lactobacillus rhamnosus GG to Caco-2 cells.

    PubMed

    Deepika, G; Rastall, R A; Charalampopoulos, D

    2011-08-24

    This study evaluated the effects of fat and sugar levels on the surface properties of Lactobacillus rhamnosus GG during storage in food model systems, simulating yogurt and ice cream, and related them with the ability of the bacterial cells to adhere to Caco-2 cells. Freeze-dried L. rhamnosus GG cells were added to the model food systems and stored for 7 days. The bacterial cells were analyzed for cell viability, hydrophobicity, ζ potential, and their ability to adhere to Caco-2 cells. The results indicated that the food type and its composition affected the surface and adhesion properties of the bacterial cells during storage, with yogurt being a better delivery vehicle than ice cream in terms of bacterial adhesion to Caco-2 cells. The most important factor influencing bacterial adhesion was the storage time rather than the levels of fats and sugars, indicating that conformational changes were taking place on the surface of the bacterial cells during storage.

  3. The Evolutionary Origin of Epithelial Cell-Cell Adhesion Mechanisms

    PubMed Central

    Miller, Phillip W.; Clarke, Donald N.; Weis, William I.; Lowe, Christopher J.; Nelson, W. James

    2014-01-01

    SUMMARY A simple epithelium forms a barrier between the outside and the inside of an organism, and is the first organized multicellular tissue found in evolution. We examine the relationship between the evolution of epithelia and specialized cell-cell adhesion proteins comprising the classical cadherin/β-catenin/α-catenin complex (CCC). A review of the divergent functional properties of the CCC in metazoans and non-metazoans, and an updated phylogenetic coverage of the CCC using recent genomic data reveal: 1) The core CCC likely originated before the last common ancestor of unikonts and their closest bikont sister taxa. 2) Formation of the CCC may have constrained sequence evolution of the classical cadherin cytoplasmic domain and β-catenin in metazoa. 3) The α-catenin binding domain in β-catenin appears to be the favored mutation site for disrupting β-catenin function in the CCC. 4) The ancestral function of the α/β-catenin heterodimer appears to be an actin-binding module. In some metazoan groups, more complex functions of α-catenin were gained by sequence divergence in the non-actin binding (N-, M-) domains. 5) Allosteric regulation of α-catenin, rather than loss of function mutations, may have evolved for more complex regulation of the actin cytoskeleton. PMID:24210433

  4. Focal adhesion complex proteins in epidermis and squamous cell carcinoma

    PubMed Central

    Duperret, Elizabeth K; Ridky, Todd W

    2013-01-01

    Focal adhesions (FAs) are large, integrin-containing, multi-protein assemblies spanning the plasma membrane that link the cellular cytoskeleton to surrounding extracellular matrix. They play critical roles in adhesion and cell signaling and are major regulators of epithelial homeostasis, tissue response to injury, and tumorigenesis. Most integrin subunits and their associated FA proteins are expressed in skin, and murine genetic models have provided insight into the functional roles of FAs in normal and neoplastic epidermis. Here, we discuss the roles of these proteins in normal epidermal proliferation, adhesion, wound healing, and cancer. While many downstream signaling mechanisms remain unclear, the critically important roles of FAs are highlighted by the development of therapeutics targeting FAs for human cancer. PMID:24036537

  5. Endoglin regulates mural cell adhesion in the circulatory system.

    PubMed

    Rossi, Elisa; Smadja, David M; Boscolo, Elisa; Langa, Carmen; Arevalo, Miguel A; Pericacho, Miguel; Gamella-Pozuelo, Luis; Kauskot, Alexandre; Botella, Luisa M; Gaussem, Pascale; Bischoff, Joyce; Lopez-Novoa, José M; Bernabeu, Carmelo

    2016-04-01

    The circulatory system is walled off by different cell types, including vascular mural cells and podocytes. The interaction and interplay between endothelial cells (ECs) and mural cells, such as vascular smooth muscle cells or pericytes, play a pivotal role in vascular biology. Endoglin is an RGD-containing counter-receptor for β1 integrins and is highly expressed by ECs during angiogenesis. We find that the adhesion between vascular ECs and mural cells is enhanced by integrin activators and inhibited upon suppression of membrane endoglin or β1-integrin, as well as by addition of soluble endoglin (SolEng), anti-integrin α5β1 antibody or an RGD peptide. Analysis of different endoglin mutants, allowed the mapping of the endoglin RGD motif as involved in the adhesion process. In Eng (+/-) mice, a model for hereditary hemorrhagic telangectasia type 1, endoglin haploinsufficiency induces a pericyte-dependent increase in vascular permeability. Also, transgenic mice overexpressing SolEng, an animal model for preeclampsia, show podocyturia, suggesting that SolEng is responsible for podocytes detachment from glomerular capillaries. These results suggest a critical role for endoglin in integrin-mediated adhesion of mural cells and provide a better understanding on the mechanisms of vessel maturation in normal physiology as well as in pathologies such as preeclampsia or hereditary hemorrhagic telangiectasia.

  6. On the relation between surface roughness of metallic substrates and adhesion of human primary bone cells.

    PubMed

    Anselme, K; Bigerelle, M

    2014-01-01

    Surface characteristics of materials, whether their topography, chemistry, or surface energy, play an essential part in osteoblast adhesion on biomaterials. Thus, the quality of cell adhesion will influence the cell's capacity to proliferate and differentiate in contact with a biomaterial. We have developed for more than ten years numerous studies on the influence of topography and chemistry of metallic substrates on the response of primary human bone cells. The originality of our approach is that contrary to most of other authors, we quantified the adhesion of primary human bone cells on metallic substrates with perfectly characterized surface topography after some hours but also over 21 days. Moreover, we have developed original statistical approaches for characterizing the relation between surface roughness and cell-adhesion parameters. In this article, we will illustrate different studies we did these last ten years concerning the development of a new adhesion parameter, the adhesion power; the correlation between short-term adhesion, long-term adhesion, and proliferation; the influence of roughness organization on cell adhesion and the development of the order parameter; our modeling approach of cell adhesion on surface topography; the relative influence of surface chemistry and topography on cell adhesion and contact angle; the relation between surface features dimensions and cell adhesion. Further, some considerations will be given on the methods for scanning surface topography for cell-adhesion studies. Finally, perspectives will be given to elucidate these intracellular mechanotransduction mechanisms induced by the deformation of cells on model sinusoidal peaks-or-valleys surfaces.

  7. Micromechanical and surface adhesive properties of single saccharomyces cerevisiae cells

    NASA Astrophysics Data System (ADS)

    Farzi, Bahman; Cetinkaya, Cetin

    2017-09-01

    The adhesion and mechanical properties of a biological cell (e.g. cell membrane elasticity and adhesiveness) are often strong indicators for the state of its health. Many existing techniques for determining mechanical properties of cells require direct physical contact with a single cell or a group of cells. Physical contact with the cell can trigger complex mechanotransduction mechanisms, leading to cellular responses, and consequently interfering with measurement accuracy. In the current work, based on ultrasonic excitation and interferometric (optical) motion detection, a non-contact method for characterizing the adhesion and mechanical properties of single cells is presented. It is experimentally demonstrated that the rocking (rigid body) motion and internal vibrational resonance frequencies of a single saccharomyces cerevisiae (SC) (baker’s yeast) cell can be acquired with the current approach, and the Young’s modulus and surface tension of the cell membrane as well as surface adhesion energy can be extracted from the values of these acquired resonance frequencies. The detected resonance frequency ranges for single SC cells include a rocking (rigid body) frequency of 330  ±  70 kHz and two breathing resonance frequencies of 1.53  ±  0.12 and 2.02  ±  0.31 MHz. Based on these values, the average work-of-adhesion of SC cells on a silicon substrate in aqueous medium is extracted, for the first time, as WASC-Si=16.2+/- 3.8 mJ {{m}-2} . Similarly, the surface tension and the Young’s modulus of the SC cell wall are predicted as {{σ }SC}=0.16+/- 0.02 N {{m}-1} and {{E}SC}= 9.20  ±  2.80 MPa, respectively. These results are compared to those reported in the literature by utilizing various methods, and good agreements are found. The current approach eliminates the measurement inaccuracies associated with the physical contact. Exciting and detecting cell dynamics at micro-second time-scales is significantly faster than the

  8. Model of Cell Crawling Controlled by Mechanosensitive Adhesion

    NASA Astrophysics Data System (ADS)

    Leoni, M.; Sens, P.

    2017-06-01

    We study the motility of model cells and biomimetic soft objects crawling over a substrate covered with adhesive linkers. The cell exerts traction forces on the substrate through the active periodic motion of molecular complexes to which the linkers bind and unbind stochastically. We first show that the diffusion coefficient of a force dipole (unable by symmetry to perform directed motion) is maximal for a finite ratio of the unbinding to binding rates, highlighting the role of adhesion kinetics on cell translocation. We next show that cells exerting more complex traction force distributions may exhibit directed motion only if the linkers are mechanosensitive, i.e., if the bonds' lifetime decreases (slip bonds) or increases (catch bonds) under stress. The average migration speed is higher in the catch-bond regime but so are the fluctuations, yielding a biased diffusive motion characterized by a Peclet number smaller than in the slip-bond regime.

  9. Adhesion GPCRs Govern Polarity of Epithelia and Cell Migration.

    PubMed

    Strutt, David; Schnabel, Ralf; Fiedler, Franziska; Prömel, Simone

    2016-01-01

    In multicellular organisms cells spatially arrange in a highly coordinated manner to form tissues and organs, which is essential for the function of an organism. The component cells and resulting structures are often polarised in one or more axes, and how such polarity is established and maintained correctly has been one of the major biological questions for many decades. Research progress has shown that many adhesion GPCRs (aGPCRs) are involved in several types of polarity. Members of the two evolutionarily oldest groups, Flamingo/Celsr and Latrophilins, are key molecules in planar cell polarity of epithelia or the propagation of cellular polarity in the early embryo, respectively. Other adhesion GPCRs play essential roles in cell migration, indicating that this receptor class includes essential molecules for the control of various levels of cellular organisation.

  10. Cell adhesion defines the topology of endocytosis and signaling

    PubMed Central

    Grossier, Jean-Philippe; Xouri, Georgia; Goud, Bruno; Schauer, Kristine

    2014-01-01

    Preferred sites of endocytosis have been observed in various cell types, but whether they occur randomly or are linked to cellular cues is debated. Here, we quantified the sites of endocytosis of transferrin (Tfn) and epidermal growth factor (EGF) in cells whose adhesion geometry was defined by micropatterns. 3D probabilistic density maps revealed that Tfn was enriched in adhesive sites during uptake, whereas EGF endocytosis was restricted to the dorsal cellular surface. This spatial separation was not due to distributions of corresponding receptors but was regulated by uptake mechanisms. Asymmetric uptake of Tfn resulted from the enrichment of clathrin and adaptor protein 2 at adhesive areas. Asymmetry in EGF uptake was strongly dependent on the actin cytoskeleton and led to asymmetry in EGF receptor activation. Mild alteration of actin dynamics abolished asymmetry in EGF uptake and decreased EGF-induced downstream signaling, suggesting that cellular adhesion cues influence signal propagation. We propose that restriction of endocytosis at distinct sites allows cells to sense their environment in an “outside-in” mechanism. PMID:24366944

  11. Dcas Supports Cell Polarization and Cell-Cell Adhesion Complexes in Development

    PubMed Central

    Tikhmyanova, Nadezhda; Tulin, Alexei V.; Roegiers, Fabrice; Golemis, Erica A.

    2010-01-01

    Mammalian Cas proteins regulate cell migration, division and survival, and are often deregulated in cancer. However, the presence of four paralogous Cas family members in mammals (BCAR1/p130Cas, EFS/Sin1, NEDD9/HEF1/Cas-L, and CASS4/HEPL) has limited their analysis in development. We deleted the single Drosophila Cas gene, Dcas, to probe the developmental function of Dcas. Loss of Dcas had limited effect on embryonal development. However, we found that Dcas is an important modulator of the severity of the developmental phenotypes of mutations affecting integrins (If and mew) and their downstream effectors Fak56D or Src42A. Strikingly, embryonic lethal Fak56D-Dcas double mutant embryos had extensive cell polarity defects, including mislocalization and reduced expression of E-cadherin. Further genetic analysis established that loss of Dcas modified the embryonal lethal phenotypes of embryos with mutations in E-cadherin (Shg) or its signaling partners p120- and β-catenin (Arm). These results support an important role for Cas proteins in cell-cell adhesion signaling in development. PMID:20808771

  12. Cytostasis and morphological changes induced by mifepristone in human metastatic cancer cells involve cytoskeletal filamentous actin reorganization and impairment of cell adhesion dynamics

    PubMed Central

    2013-01-01

    Background Changes in cell shape and plasticity in cytoskeletal dynamics are critically involved in cell adhesion, migration, invasion and the overall process of metastasis. Previous work in our laboratory demonstrated that the synthetic steroid mifepristone inhibited the growth of highly metastatic cancer cells, while simultaneously causing striking changes in cellular morphology. Here we assessed whether such morphological alterations developed in response to cytostatic concentrations of mifepristone are reversible or permanent, involve rearrangement of cytoskeletal proteins, and/or affect the adhesive capacity of the cells. Methods Cancer cell lines of the ovary (SKOV-3), breast (MDA-MB-231), prostate (LNCaP), and nervous system (U87MG) were exposed to cytostatic concentrations of mifepristone and studied by phase-contrast microscopy. The transient or permanent nature of the cytostasis and morphological changes caused by mifepristone was assessed, as well as the rearrangement of cytoskeletal proteins. De-adhesion and adhesion assays were utilized to determine if mifepristone-arrested and morphologically dysregulated cells had abnormal de-adhesion/adhesion dynamics when compared to vehicle-treated controls. Results Mifepristone-treated cells displayed a long, thin, spindle-like shape with boundaries resembling those of loosely adhered cells. Growth arrest and morphology changes caused by mifepristone were reversible in SKOV-3, MDA-MB-231 and U87MG, but not in LNCaP cells that instead became senescent. All cancer cell types exposed to mifepristone displayed greatly increased actin ruffling in association with accelerated de-adhesion from the culture plate, and delayed adhesion capacity to various extracellular matrix components. Conclusions Cytostatic concentrations of mifepristone induced alterations in the cellular structure of a panel of aggressive, highly metastatic cancer cells of different tissues of origin. Such changes were associated with re

  13. A Review of Cell Adhesion Studies for Biomedical and Biological Applications

    PubMed Central

    Ahmad Khalili, Amelia; Ahmad, Mohd Ridzuan

    2015-01-01

    Cell adhesion is essential in cell communication and regulation, and is of fundamental importance in the development and maintenance of tissues. The mechanical interactions between a cell and its extracellular matrix (ECM) can influence and control cell behavior and function. The essential function of cell adhesion has created tremendous interests in developing methods for measuring and studying cell adhesion properties. The study of cell adhesion could be categorized into cell adhesion attachment and detachment events. The study of cell adhesion has been widely explored via both events for many important purposes in cellular biology, biomedical, and engineering fields. Cell adhesion attachment and detachment events could be further grouped into the cell population and single cell approach. Various techniques to measure cell adhesion have been applied to many fields of study in order to gain understanding of cell signaling pathways, biomaterial studies for implantable sensors, artificial bone and tooth replacement, the development of tissue-on-a-chip and organ-on-a-chip in tissue engineering, the effects of biochemical treatments and environmental stimuli to the cell adhesion, the potential of drug treatments, cancer metastasis study, and the determination of the adhesion properties of normal and cancerous cells. This review discussed the overview of the available methods to study cell adhesion through attachment and detachment events. PMID:26251901

  14. The MIG-2/integrin interaction strengthens cell-matrix adhesion and modulates cell motility.

    PubMed

    Shi, Xiaohua; Ma, Yan-Qing; Tu, Yizeng; Chen, Ka; Wu, Shan; Fukuda, Koichi; Qin, Jun; Plow, Edward F; Wu, Chuanyue

    2007-07-13

    Integrin-mediated cell-matrix adhesion plays an important role in control of cell behavior. We report here that MIG-2, a widely expressed focal adhesion protein, interacts with beta1 and beta3 integrin cytoplasmic domains. Integrin binding is mediated by a single site within the MIG-2 FERM domain. Functionally, the MIG-2/integrin interaction recruits MIG-2 to focal adhesions. Furthermore, using alphaIIbbeta3 integrin-expressing Chinese hamster ovary cells, a well described model system for integrin activation, we show that MIG-2 promotes integrin activation and enhances cell-extracellular matrix adhesion. Although MIG-2 is expressed in many cell types, it is deficient in certain colon cancer cells. Expression of MIG-2, but not of an integrin binding-defective MIG-2 mutant, in MIG-2-null colon cancer cells strengthened cell-matrix adhesion, promoted focal adhesion formation, and reduced cell motility. These results suggest that the MIG-2/integrin interaction is an important element in the cellular control of integrin-mediated cell-matrix adhesion and that loss of this interaction likely contributes to high motility of colon cancer cells.

  15. The role of adhesion energy in controlling cell–cell contacts

    PubMed Central

    Maître, Jean-Léon; Heisenberg, Carl-Philipp

    2011-01-01

    Recent advances in microscopy techniques and biophysical measurements have provided novel insight into the molecular, cellular and biophysical basis of cell adhesion. However, comparably little is known about a core element of cell–cell adhesion—the energy of adhesion at the cell–cell contact. In this review, we discuss approaches to understand the nature and regulation of adhesion energy, and propose strategies to determine adhesion energy between cells in vitro and in vivo. PMID:21807491

  16. [Effects of endothelial lipase on mRNA expression of adhesion molecule of human umbilical vascular endothelial cells].

    PubMed

    Fang, Yu-qiang; Huang, Lan; Zhao, Xiao-hui; Yin, Yang-guang; Kang, Hua-li; Deng, Meng-yang

    2007-12-01

    To explore the relationship between human umbilical vascular endothelial cells (HUVECs) and endothelial lipase (EL), and the effect of EL on expression of endothelial cell adhesion molecule (ICAM). HUVECs was treated with tumor necrosis factor-alpha(TNF-alpha) 10 microg/L and the mRNA of adhesion molecules [intercellular adhesion molecule-1 (ICAM-1), vascular cellular adhesion molecule-1 (VCAM-1) and E-selectin] were detected by reverse transcription-polymerase chain reaction (RT-PCR). Then the effect of 50 microg/L anti-endothelial lipase (anti-EL) antibody on the influence of TNF-alpha on these adhesion molecules was observed. After being treated with TNF-alpha, the mRNA of adhesion molecules expressed by HUVECs were significant up-regulated, there was significant difference compared with control group (all P<0.01). These effects of TNF-alpha were significantly abolished by 50 microg/L anti-EL antibody (P<0.05 or P<0.01). EL can affect the expression of adhesion molecules on endothelial cell adhesion molecule. This effect of EL may play a role in the pathophysiologic process in the pathogenesis progress of atherosclerosis.

  17. Understanding dynamic changes in live cell adhesion with neutron reflectometry

    NASA Astrophysics Data System (ADS)

    Junghans, Ann

    Understanding the structure and functionality of biological systems on a nanometer-resolution and short temporal scales is important for solving complex biological problems, developing innovative treatment, and advancing the design of highly functionalized biomimetic materials. For example, adhesion of cells to an underlying substrate plays a crucial role in physiology and disease development, and has been investigated with great interest for several decades. In the talk, we would like to highlight recent advances in utilizing neutron scattering to study bio-related structures in dynamic conditions (e . g . under the shear flow) including in-situ investigations of the interfacial properties of living cells. The strength of neutron reflectometry is its non-pertubative nature, the ability to probe buried interfaces with nanometer resolution and its sensitivity to light elements like hydrogen and carbon. That allows us to study details of cell - substrate interfaces that are not accessible with any other standard techniques. We studied the adhesion of human brain tumor cells (U251) to quartz substrates and their responses to the external mechanical forces. Such cells are isolated within the central nervous system which makes them difficult to reach with conventional therapies and therefore making them highly invasive. Our results reveal changes in the thickness and composition of the adhesion layer (a layer between the cell lipid membrane and the quartz substrate), largely composed of hyaluronic acid and associated proteoglycans, when the cells were subjected to shear stress. Further studies will allow us to determine more conditions triggering changes in the composition of the bio-material in the adhesion layer. This, in turn, can help to identify changes that correlate with tumor invasiveness, which can have significant medical impact for the development of targeted anti-invasive therapies.

  18. Encapsulation of cell-adhesive RGD peptides into a polymeric physical hydrogel to prevent postoperative tissue adhesion.

    PubMed

    Zhang, Zheng; Ni, Jian; Chen, Liang; Yu, Lin; Xu, Jianwei; Ding, Jiandong

    2012-08-01

    Peptides containing the sequence of arginine-glycine-aspartate (RGD), a famous adhesion moiety, can specifically conjugate integrins in cell membranes, and are usually applied to enhance cell adhesion after linking to solid substrates in tissue engineering or to nanoparticles in targeting delivery. This paper reveals, however, that free RGD peptides can assist in preventing tissue adhesion by blocking focal adhesion between cells and surfaces of barrier devices. In order to avoid a rapid peptide loss after straightforward injection of a peptide solution, we employed a thermosensitive injectable hydrogel composed of a biodegradable block copolymer poly(ε-caprolactone-co-lactide)-poly(ethylene glycol)-poly(ε-caprolactone-co-lactide) (PCLA-PEG-PCLA) to encapsulate peptides cyclo(-RGDfK-). A sustainable release for one week was achieved in vitro. The rabbit model of sidewall defect and bowel abrasion was selected to examine the in vivo anti-adhesion efficacy. It reveals a significant reduction of postoperative peritoneal adhesion in the group of RGD-loaded PCLA-PEG-PCLA hydrogels. We interpret this excellent efficacy by the combination of two effects: first, our hydrogel affords a physical barrier to prevent adhesion between injured abdominal wall and cecum; second, the RGD molecules as integrin blockers released from the hydrogel assist the anti-adhesion. Copyright © 2012 Wiley Periodicals, Inc.

  19. Diversity of cell-mediated adhesions in breast cancer spheroids.

    PubMed

    Ivascu, Andrea; Kubbies, Manfred

    2007-12-01

    Due to their three dimensional (3D) architecture, multicellular tumor spheroids mimic avascular tumor areas comprising the establishment of diffusion gradients, reduced proliferation rates and increased drug resistance. We have shown recently that the spontaneous formation of spheroids is restricted to a limited number of cell lines whereas the majority grow only as aggregates of cells with loose cell-cell contacts when cultured in 3D. However, by the addition of reconstituted basement membrane (rBM, Matrigel), aggregates can be transformed into spheroids with diffusion barriers and development of quiescent therapy-resistant cells. In this report, we investigated adhesion molecules responsible for rBM-driven versus spontaneous spheroid formation in a diverse population of eight breast tumor cell lines relevant for in vitro and in vivo antitumor drug testing. Inhibition of spheroid formation was monitored in the presence of adhesion molecule functional blocking antibodies and after siRNA-mediated down-regulation of E- and N-cadherin and integrin beta1 adhesion receptors. We identified that E-cadherin mediates the spontaneous formation of spheroids in MCF7, BT-474, T-47D and MDA-MB-361 cells, whereas N-cadherin is responsible for tight packing of MDA-MB-435S cells. In contrast, the matrix protein-induced transformation of 3D aggregates into spheroids in MDA-MB-231 and SK-BR-3 cells is mediated primarily by the collagen I/integrin beta1 interaction with no cadherin involvement. A combination of both, homophilic E-cadherin and integrin beta1/collagen I interaction establishes spheroids in MDA-MB-468 cells. These findings indicate that an evolutionary diverse and complex pattern of interacting cell surface proteins exists in breast cancer cells that determines the 3D growth characteristic in vitro, thereby influencing small molecule or antibody permeation in preclinical in vitro and in vivo tumor models.

  20. Laser-based microfabrication for cell adhesion and migration

    NASA Astrophysics Data System (ADS)

    Miller, Jordan S.

    Mammalian cell adhesion and migration impact a multitude of cellular behaviors and tissue remodeling processes. Over the past several decades, investigators have methodically improved in vitro systems as mimics of the extracellular microenvironment to study these biologic phenomena. Experiments have progressed from early studies on bifunctional inorganic surfaces to those with purified adhesive proteins against an organic, non-adhesive background. Recently, subcellular geometric patterns of adhesive proteins have proven useful to restrict and direct focal contact formation, cell survival, lamellopodia extension, and the maturation of "supermature" focal contacts. The vast majority of recent studies have involved the construction of hydrophobic patches with adsorbed fibronectin as the adhesive constraint of choice. However, the extracellular matrix (ECM) in which cells operate is a complex and diverse environment where numerous signals interact with a cell simultaneously; signals that the cell must integrate and that directly impact these processes. Microfabrication methods to approximate the extracellular milieu have significant limitations in their potential to be extended to pattern multiple bioactive ligands with high precision. Current techniques require multi-step processes which lose feature fidelity at every pattern transfer step, while simultaneously increasing logistical complexity and the chance of technical missteps. We have developed a family of complementary techniques using the raster-scanning laser of a confocal microscope to address a number of current challenges in improving microfabrication. For our work with thin films of self-assembled organic monolayers, we systematically removed the multi-step processing requirements of conventional photolithographic microfabrication and characterized and verified the technical advantages of our new patterning techniques. For 3D work, we developed and demonstrated micron-scale biochemical and mechanical

  1. Modeling keratinocyte wound healing dynamics: Cell-cell adhesion promotes sustained collective migration.

    PubMed

    Nardini, John T; Chapnick, Douglas A; Liu, Xuedong; Bortz, David M

    2016-07-07

    The in vitro migration of keratinocyte cell sheets displays behavioral and biochemical similarities to the in vivo wound healing response of keratinocytes in animal model systems. In both cases, ligand-dependent Epidermal Growth Factor Receptor (EGFR) activation is sufficient to elicit collective cell migration into the wound. Previous mathematical modeling studies of in vitro wound healing assays assume that physical connections between cells have a hindering effect on cell migration, but biological literature suggests a more complicated story. By combining mathematical modeling and experimental observations of collectively migrating sheets of keratinocytes, we investigate the role of cell-cell adhesion during in vitro keratinocyte wound healing assays. We develop and compare two nonlinear diffusion models of the wound healing process in which cell-cell adhesion either hinders or promotes migration. Both models can accurately fit the leading edge propagation of cell sheets during wound healing when using a time-dependent rate of cell-cell adhesion strength. The model that assumes a positive role of cell-cell adhesion on migration, however, is robust to changes in the leading edge definition and yields a qualitatively accurate density profile. Using RNAi for the critical adherens junction protein, α-catenin, we demonstrate that cell sheets with wild type cell-cell adhesion expression maintain migration into the wound longer than cell sheets with decreased cell-cell adhesion expression, which fails to exhibit collective migration. Our modeling and experimental data thus suggest that cell-cell adhesion promotes sustained migration as cells pull neighboring cells into the wound during wound healing.

  2. Rapid and Localized Mechanical Stimulation and Adhesion Assay: TRPM7 Involvement in Calcium Signaling and Cell Adhesion

    PubMed Central

    Nishitani, Wagner Shin; Alencar, Adriano Mesquita; Wang, Yingxiao

    2015-01-01

    A cell mechanical stimulation equipment, based on cell substrate deformation, and a more sensitive method for measuring adhesion of cells were developed. A probe, precisely positioned close to the cell, was capable of a vertical localized mechanical stimulation with a temporal frequency of 207 Hz, and strain magnitude of 50%. This setup was characterized and used to probe the response of Human Umbilical Endothelial Vein Cells (HUVECs) in terms of calcium signaling. The intracellular calcium ion concentration was measured by the genetically encoded Cameleon biosensor, with the Transient Receptor Potential cation channel, subfamily M, member 7 (TRPM7) expression inhibited. As TRPM7 expression also regulates adhesion, a relatively simple method for measuring adhesion of cells was also developed, tested and used to study the effect of adhesion alone. Three adhesion conditions of HUVECs on polyacrylamide gel dishes were compared. In the first condition, the substrate is fully treated with Sulfo-SANPAH crosslinking and fibronectin. The other two conditions had increasingly reduced adhesion: partially treated (only coated with fibronectin, with no use of Sulfo-SANPAH, at 5% of the normal amount) and non-treated polyacrylamide gels. The cells showed adhesion and calcium response to the mechanical stimulation correlated to the degree of gel treatment: highest for fully treated gels and lowest for non-treated ones. TRPM7 inhibition by siRNA on HUVECs caused an increase in adhesion relative to control (no siRNA treatment) and non-targeting siRNA, but a decrease to 80% of calcium response relative to non-targeting siRNA which confirms the important role of TRPM7 in mechanotransduction despite the increase in adhesion. PMID:25946314

  3. Rapid and Localized Mechanical Stimulation and Adhesion Assay: TRPM7 Involvement in Calcium Signaling and Cell Adhesion.

    PubMed

    Nishitani, Wagner Shin; Alencar, Adriano Mesquita; Wang, Yingxiao

    2015-01-01

    A cell mechanical stimulation equipment, based on cell substrate deformation, and a more sensitive method for measuring adhesion of cells were developed. A probe, precisely positioned close to the cell, was capable of a vertical localized mechanical stimulation with a temporal frequency of 207 Hz, and strain magnitude of 50%. This setup was characterized and used to probe the response of Human Umbilical Endothelial Vein Cells (HUVECs) in terms of calcium signaling. The intracellular calcium ion concentration was measured by the genetically encoded Cameleon biosensor, with the Transient Receptor Potential cation channel, subfamily M, member 7 (TRPM7) expression inhibited. As TRPM7 expression also regulates adhesion, a relatively simple method for measuring adhesion of cells was also developed, tested and used to study the effect of adhesion alone. Three adhesion conditions of HUVECs on polyacrylamide gel dishes were compared. In the first condition, the substrate is fully treated with Sulfo-SANPAH crosslinking and fibronectin. The other two conditions had increasingly reduced adhesion: partially treated (only coated with fibronectin, with no use of Sulfo-SANPAH, at 5% of the normal amount) and non-treated polyacrylamide gels. The cells showed adhesion and calcium response to the mechanical stimulation correlated to the degree of gel treatment: highest for fully treated gels and lowest for non-treated ones. TRPM7 inhibition by siRNA on HUVECs caused an increase in adhesion relative to control (no siRNA treatment) and non-targeting siRNA, but a decrease to 80% of calcium response relative to non-targeting siRNA which confirms the important role of TRPM7 in mechanotransduction despite the increase in adhesion.

  4. Adhesion receptors as therapeutic targets for circulating tumor cells

    PubMed Central

    Li, Jiahe; King, Michael R.

    2012-01-01

    Metastasis contributes to >90% of cancer-associated mortality. Though primary tumors can be removed by surgical resection or chemo/radiotherapy, metastatic disease is a great challenge to treatment due to its systemic nature. As metastatic “seeds,” circulating tumor cells (CTCs) are believed to be responsible for dissemination from a primary tumor to anatomically distant organs. Despite the possibility of physical trapping of CTCs in microvessels, recent advances have provided insights into the involvement of a variety of adhesion molecules on CTCs. Such adhesion molecules facilitate direct interaction with the endothelium in specific tissues or indirectly through leukocytes. Importantly, significant progress has been made in understanding how these receptors confer enhanced invasion and survival advantage during hematogenous circulation of CTCs through recruitment of macrophages, neutrophils, platelets, and other cells. This review highlights the identification of novel adhesion molecules and how blocking their function can compromise successful seeding and colonization of CTCs in new microenvironment. Encouraged by existing diagnostic tools to identify and isolate CTCs, strategic targeting of these adhesion molecules to deliver conventional chemotherapeutics or novel apoptotic signals is discussed for the neutralization of CTCs in the circulation. PMID:22837985

  5. Surface characteristics and cell adhesion: a comparative study of four commercial dental implants.

    PubMed

    Liu, Ruohong; Lei, Tianhua; Dusevich, Vladimir; Yao, Xiamei; Liu, Ying; Walker, Mary P; Wang, Yong; Ye, Ling

    2013-12-01

    The aims of this study were to compare surface properties of four commercial dental implants and to compare those implant systems' cell adhesion, which may be affected by the surface properties, and to provide scientific information on the selection of implants for clinicians. The surface properties of four commonly used dental implants (3i Nanotite™, Astra OsseoSpeed™, Nobel Biocare TiUnite®, and Straumann SLActive®) were studied using MicroSpy profiler, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, and Raman microspectroscopy. Primary mouse alveolar bone cells were cultured on the surface of implants from the four companies. After 48-hour culture, SEM in combination with a quantitative analysis of SEM images was used to examine the cell adhesion. Cell adhesion rates (ratios of cell surface to implant surface) among different systems were compared. Distinct differences were found among these implants. Comparisons of roughness among three locations: flank, top, and valley within the same implant system, or in the same location among different implants were made. Generally Astra and Straumann systems showed the roughest surface, whereas 3i showed the smoothest surface. Multiple cracks were found on the surface of the Nobel Biocare system, which also had a dramatically lower level of titanium. In addition, rutile phase of titanium oxide was found in 3i, Astra, and Straumann systems, and anatase phase of titanium oxide was only detected in the Nobel Biocare system. After 48-hour culture, Astra and Straumann systems displayed the highest cell adhesion at the areas of flank, top, and valley of the implant surface. Primary cells also reached confluence on the valley, but significantly less in the 3i system. Nobel Biocare showed the least cell adhesion on the flank and valley. Implant systems have distinct differences in surface properties, leading to different cell adhesion results. Further in vivo study is needed to study the impact of

  6. Soluble Intracellular Adhesion Molecule-1 in Patients with Unipolar or Bipolar Affective Disorders: Results from a Pilot Trial.

    PubMed

    Schaefer, Martin; Sarkar, Susanne; Schwarz, Markus; Friebe, Astrid

    2016-01-01

    Immunological and vascular markers may play a role in the pathophysiology of mood disorders and mood changes. To test whether the cell adhesion molecule soluble intracellular adhesion molecule-1 (sICAM-1) may serve as a biomarker for patients with unipolar or bipolar affective disorders when compared to a healthy control group, and whether sICAM-1 blood levels change during different mood states. sICAM-1 serum concentrations were compared between 20 healthy controls and 48 patients with affective disorders (unipolar, bipolar II and bipolar I disorder) during different mood states (euthymic mood state, depression or mania). When compared to healthy controls, patients with affective disorders had significantly higher sICAM-1 levels during the euthymic state (p = 0.015). Differences became more pronounced during depression (p = 0.013). When unipolar and bipolar patients were analyzed separately, unipolar patients significantly differed from controls during the euthymic and depressive mood state, while bipolar II patients showed a trend towards higher sICAM-1 levels during depression. Patients with bipolar I disorders had significantly higher sICAM-1 levels during manic states when compared to controls (p = 0.007). sICAM-1 elevation in unipolar and bipolar patients, independent of mood changes, might support the hypothesis of chronic immune activation and endothelial dysfunction in patients with affective disorders. © 2016 S. Karger AG, Basel.

  7. Induction of hyper-adhesion attenuates autoimmune-induced keratinocyte cell-cell detachment and processing of adhesion molecules via mechanisms that involve PKC.

    PubMed

    Cirillo, Nicola; Lanza, Alessandro; Prime, Stephen S

    2010-02-15

    In confluent keratinocyte monolayers, desmosomal adhesion gradually becomes calcium-independent and this is associated with an increase in the strength of intercellular adhesion (hyper-adhesion). In this study, we investigated the functional and molecular significance of hyper-adhesion in a system challenged by autoimmune sera from patients with Pemphigus Vulgaris (PV), a disease primarily targeting desmosomal adhesion. The results show that keratinocytes with calcium-independent desmosomes are resistant to disruption of intercellular contacts (acantholysis) in experimental PV. Furthermore, both the desmosomal cadherins desmoglein (Dsg) 1 and Dsg3 and the adherens junction protein E-cadherin were decreased in confluent keratinocytes at Day 1, but not in hyper-adhesive cells (Day 6) after incubation with PV serum. Pharmacological induction of the hyper-adhesive state with the PKC inhibitor Go6976 reduced both the acantholysis rate and the processing of cell adhesion molecules induced by PV serum. When the establishment of the hyper-adhesive state was prevented by cell adhesion recognition (CAR) peptides that perturbed desmosomal interactions, Go6976 could still partially attenuate PV acantholysis. Taken together, these data demonstrate that keratinocyte hyper-adhesion decreases the morphological, functional and biochemical dys-cohesive effects of PV serum via mechanisms that involve, at least in part, the function of PKC. This suggests that reinforcing keratinocyte adhesion may be a promising way to inhibit the effects of this most debilitating disorder. Crown Copyright 2009. Published by Elsevier Inc. All rights reserved.

  8. Sickle cell disease biochip: a functional red blood cell adhesion assay for monitoring sickle cell disease

    PubMed Central

    ALAPAN, YUNUS; KIM, CEONNE; ADHIKARI, ANIMA; GRAY, KAYLA E.; GURKAN-CAVUSOGLU, EVREN; LITTLE, JANE A.; GURKAN, UMUT A.

    2016-01-01

    Sickle cell disease (SCD) afflicts millions of people worldwide and is associated with considerable morbidity and mortality. Chronic and acute vaso-occlusion are the clinical hallmarks of SCD and can result in pain crisis, widespread organ damage, and early movtality. Even though the molecular underpinnings of SCD were identified more than 60 years ago, there are no molecular or biophysical markers of disease severity that are feasibly measured in the clinic. Abnormal cellular adhesion to vascular endothelium is at the root of vaso-occlusion. However, cellular adhesion is not currently evaluated clinically. Here, we present a clinically applicable microfluidic device (SCD biochip) that allows serial quantitative evaluation of red blood cell (RBC) adhesion to endothelium-associated protein-immobilized microchannels, in a closed and preprocessing-free system. With the SCD biochip, we have analyzed blood samples from more than 100 subjects and have shown associations between the measured RBC adhesion to endothelium-associated proteins (fibronectin and laminin) and individual RBC characteristics, including hemoglobin content, fetal hemoglobin concentration, plasma lactate dehydrogenase level, and reticulocyte count. The SCD biochip is a functional adhesion assay, reflecting quantitative evaluation of RBC adhesion, which could be used at baseline, during crises, relative to various long-term complications, and before and after therapeutic interventions. PMID:27063958

  9. Cell adhesion and apoptosis in ovarian stromal hyperplasia and hyperthecosis.

    PubMed

    Sharabidze, N; Burkadze, G; Sabakhtarashvili, M

    2006-02-01

    The aim of our study was to investigate cell adhesion and apoptosis in ovarian stromal hyperplasia and hyperthecosis in reproductive women with and without polycystic ovarian disease. We have studied 104 patients with a histological diagnosis of ovarian stromal hyperthecosis and stromal hyperplasia. Paraffin sections were stained by hematoxylin-eosin, von Gieson and immunohistochemistry for Bcl-2 (anti-apoptotic protein) and E-cadherin (cell adhesion marker). We assessed the number of Bcl-2-positive and E-cadherin-positive cells. The patients were divided into 4 groups: group 1-33 patients with polycystic ovarian disease and coexistent stromal hyperthecosis, group 2-28 patients with polycystic ovarian disease and coexistent stromal hyperplasia, group 3-24 patients with ovarian stromal hyperthecosis, group 4-19 patients with ovarian stromal hyperplasia. Our results suggest that in ovarian stromal hyperthecosis and stromal hyperplasia coexistent with polycystic ovarian disease, E-cadherin-positivity in internal and external theca cells, and granulosa cells is associated with Bcl-2 expression. Therefore, ovarian cells expressing Bcl-2 and maintaining E-cadherin-positivity may be the viable cells that escape the apoptotic process. In ovarian stromal hyperthecosis without polycystic ovarian disease, luteinized stromal cells are potentially resistant to apoptosis as they are positive for Bcl-2. In ovarian stromal hyperplasia without polycystic ovarian disease, hyperplastic stromal cells are potentially susceptible to apoptosis as they are negative for Bcl-2. E-cadherin is negative both in stromal hyperthecosis and hyperplasia suggesting that E-cadherin expression in ovary is limited to granulosa and theca cells only. Described characteristics of cell adhesion and apoptosis may play a role in pathogenesis of ovarian stromal hyperthecosis and stromal hyperplasia with and without polycystic ovarian disease.

  10. Osteopontin improves adhesion and migration of human primary renal cortical epithelial cells during wound healing

    PubMed Central

    Wu, Jinfeng; Wang, Zuolin

    2016-01-01

    The aim of the present study was to investigate the effect of osteopontin (OPN) on adhesion and migration in human primary renal cortical epithelial cells during wound healing and Transwell assays. MTT assay was used to examine the cell viability and western blot analysis was used to examine the expression of cytoskeletal proteins and cell adhesion molecules. The results showed that overexpression of OPN had positive effects on the viability, proliferation, adhesion and migration of the human primary renal cortical epithelial cells. In addition, the integrity of the cell membrane and cytoskeleton of the epithelial cells was negatively affected by knockdown of OPN expression. The Transwell migration and a wound healing assays performed using OPN-knockdown cells suggested that OPN had a significant impact on cell migration (P=0.0421) and wound healing (P=0.0333). Therefore, OPN may be a potential target for the therapeutic modulation of skin repair to improve the healing rate and quality of wound healing. PMID:28101213

  11. Fulvic Acid Attenuates Resistin-Induced Adhesion of HCT-116 Colorectal Cancer Cells to Endothelial Cells.

    PubMed

    Huang, Wen-Shih; Yang, Jen-Tsung; Lu, Chien-Chang; Chang, Shun-Fu; Chen, Cheng-Nan; Su, Yu-Ping; Lee, Ko-Chao

    2015-12-09

    A high level of serum resistin has recently been found in patients with a number of cancers, including colorectal cancer (CRC). Hence, resistin may play a role in CRC development. Fulvic acid (FA), a class of humic substances, possesses pharmacological properties. However, the effect of FA on cancer pathophysiology remains unclear. The aim of this study was to investigate the effect of resistin on the endothelial adhesion of CRC and to determine whether FA elicits an antagonistic mechanism to neutralize this resistin effect. Human HCT-116 (p53-negative) and SW-48 (p53-positive) CRC cells and human umbilical vein endothelial cells (HUVECs) were used in the experiments. Treatment of both HCT-116 and SW-48 cells with resistin increases the adhesion of both cells to HUVECs. This result indicated that p53 may not regulate this resistin effect. A mechanistic study in HCT-116 cells further showed that this resistin effect occurs via the activation of NF-κB and the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). Co-treating cells with both FA and resistin revealed that FA significantly attenuated the resistin-increased NF-κB activation and ICAM-1/VCAM-1 expression and the consequent adhesion of HCT-116 cells to HUVECs. These results demonstrate the role of resistin in promoting HCT-116 cell adhesion to HUVECs and indicate that FA might be a potential candidate for the inhibition of the endothelial adhesion of CRC in response to resistin.

  12. Strong adhesion by regulatory T cells induces dendritic cell cytoskeletal polarization and contact-dependent lethargy.

    PubMed

    Chen, Jiahuan; Ganguly, Anutosh; Mucsi, Ashley D; Meng, Junchen; Yan, Jiacong; Detampel, Pascal; Munro, Fay; Zhang, Zongde; Wu, Mei; Hari, Aswin; Stenner, Melanie D; Zheng, Wencheng; Kubes, Paul; Xia, Tie; Amrein, Matthias W; Qi, Hai; Shi, Yan

    2017-02-01

    Dendritic cells are targeted by regulatory T (T reg) cells, in a manner that operates as an indirect mode of T cell suppression. In this study, using a combination of single-cell force spectroscopy and structured illumination microscopy, we analyze individual T reg cell-DC interaction events and show that T reg cells exhibit strong intrinsic adhesiveness to DCs. This increased DC adhesion reduces the ability of contacted DCs to engage other antigen-specific cells. We show that this unusually strong LFA-1-dependent adhesiveness of T reg cells is caused in part by their low calpain activities, which normally release integrin-cytoskeleton linkage, and thereby reduce adhesion. Super resolution imaging reveals that such T reg cell adhesion causes sequestration of Fascin-1, an actin-bundling protein essential for immunological synapse formation, and skews Fascin-1-dependent actin polarization in DCs toward the T reg cell adhesion zone. Although it is reversible upon T reg cell disengagement, this sequestration of essential cytoskeletal components causes a lethargic state of DCs, leading to reduced T cell priming. Our results reveal a dynamic cytoskeletal component underlying T reg cell-mediated DC suppression in a contact-dependent manner. © 2017 Chen et al.

  13. Evaluation of cell responses toward adhesives with different photoinitiating systems.

    PubMed

    Van Landuyt, Kirsten L; Krifka, Stephanie; Hiller, Karl-Anton; Bolay, Carola; Waha, Claudia; Van Meerbeek, Bart; Schmalz, Gottfried; Schweikl, Helmut

    2015-08-01

    The photoinitiator diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) is more reactive than a camphorquinone/amine (CQ) system, and TPO-based adhesives obtained a higher degree of conversion (DC) with fewer leached monomers. The hypothesis tested here is that a TPO-based adhesive is less toxic than a CQ-based adhesive. A CQ-based adhesive (SBU-CQ) (Scotchbond Universal, 3M ESPE) and its experimental counterpart with TPO (SBU-TPO) were tested for cytotoxicity in human pulp-derived cells (tHPC). Oxidative stress was analyzed by the generation of reactive oxygen species (ROS) and by the expression of antioxidant enzymes. A dentin barrier test (DBT) was used to evaluate cell viability in simulated clinical circumstances. Unpolymerized SBU-TPO was significantly more toxic than SBU-CQ after a 24h exposure, and TPO alone (EC50=0.06mM) was more cytotoxic than CQ (EC50=0.88mM), EDMAB (EC50=0.68mM) or CQ/EDMAB (EC50=0.50mM). Cultures preincubated with BSO (l-buthionine sulfoximine), an inhibitor of glutathione synthesis, indicated a minor role of glutathione in cytotoxic responses toward the adhesives. Although the generation of ROS was not detected, a differential expression of enzymatic antioxidants revealed that cells exposed to unpolymerized SBU-TPO or SBU-CQ are subject to oxidative stress. Polymerized SBU-TPO was more cytotoxic than SBU-CQ under specific experimental conditions only, but no cytotoxicity was detected in a DBT with a 200μm dentin barrier. Not only DC and monomer-release determine the biocompatibility of adhesives, but also the cytotoxicity of the (photo-)initiator should be taken into account. Addition of TPO rendered a universal adhesive more toxic compared to CQ; however, this effect could be annulled by a thin dentin barrier. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  14. IKAP/hELP1 downregulation in neuroblastoma cells causes enhanced cell adhesion mediated by contactin overexpression

    PubMed Central

    Cohen-Kupiec, Rachel; Weinstein, Shiri; Kantor, Gal; Peer, Dan

    2010-01-01

    A splicing mutation in the IKBKAP gene encoding the IKAP/hELP1 (IKAP) protein was found to be the major cause of Familial Dysautonomia (FD). This mutation affects both the normal development and survival of sensory and sympathetic neurons of the peripheral nervous system (PNS). To understand the FD phenotype it is important to study the specific role played by IKAP in developing and mature PNS neurons. We used the neuroblastoma SHSY5Y cell line, originated from neural crest adrenal tumor and simulated the FD phenotype by reducing IKAP expression with retroviral constructs. We observed that IKAP-downregulated cells formed cell clusters compared to control cells under regular culture conditions. We examined the ability of these cells to differentiate into mature neurons in the presence of laminin, an essential extracellular matrix for developing PNS neurons. We found that the cells showed reduced attachment to laminin, morphological changes and increased cell-to-cell adhesion resulting in cell aggregates. We identified Contactin as the adhesion molecule responsible for this phenotype. We show that Contactin expression is related to IKAP expression, suggesting that IKAP regulates Contactin levels for appropriate cell-cell adhesion that could modulate neuronal growth of PNS neurons during development. PMID:20671422

  15. IKAP/hELP1 down-regulation in neuroblastoma cells causes enhanced cell adhesion mediated by contactin overexpression.

    PubMed

    Cohen-Kupiec, Rachel; Weinstein, Shiri; Kantor, Gal; Peer, Dan; Weil, Miguel

    2010-01-01

    A splicing mutation in the IKBKAP gene encoding the IKAP/hELP1 (IKAP) protein was found to be the major cause of Familial Dysautonomia (FD). This mutation affects both the normal development and survival of sensory and sympathetic neurons of the peripheral nervous system (PNS). To understand the FD phenotype it is important to study the specific role played by IKAP in developing and mature PNS neurons. We used the neuroblastoma SHSY5Y cell line, originated from neural crest adrenal tumor, and simulated the FD phenotype by reducing IKAP expression with retroviral constructs. We observed that IKAP – down - regulated cells formed cell clusters compared to control cells under regular culture conditions. We examined the ability of these cells to differentiate into mature neurons in the presence of laminin, an essential extracellular matrix for developing PNS neurons. We found that the cells showed reduced attachment to laminin, morphological changes and increased cell-to-cell adhesion resulting in cell aggregates. We identified Contactin as the adhesion molecule responsible for this phenotype. We show that Contactin expression is related to IKAP expression, suggesting that IKAP regulates Contactin levels for appropriate cell-cell adhesion that could modulate neuronal growth of PNS neurons during development.

  16. Factors affecting DSAEK graft lenticle adhesion: an in vitro experimental study.

    PubMed

    Vaddavalli, Pravin K; Diakonis, Vasilios F; Canto, Ana P; Kankariya, Vardhaman P; Pappuru, Rajeev R; Ruggeri, Marco; Banitt, Michael R; Kymionis, George D; Yoo, Sonia H

    2014-06-01

    The aim of this study was to evaluate different factors that affect Descemet stripping automated endothelial keratoplasty (DSAEK) donor graft lenticle adhesion to the recipient cornea. This experimental study included 10 eye bank recipient corneas and 10 donor DSAEK lenticles. Recipient corneas were mounted on an artificial anterior chamber (AC), whereas donor lenticles were placed beneath the host cornea. Using optical coherence tomography and imaging software, the interface gap (IG) between the donor and recipient cornea was quantified to evaluate the effect of variations in AC air fill pressure, AC air fill duration, corneal massage, and corneal venting incisions on DSAEK donor graft lenticle adhesion. Different intraocular pressures (IOP) under air for the same time intervals, do not significantly correlate with the IG; nevertheless, it was noticed that the IG decreases as the IOP increases. With respect to the magnitude of AC IOP, there was no statistically significant difference when comparing 10 mm Hg with 30 mm Hg and assessing IG (P = 0.4). Complete air-fluid exchange resulted in significantly higher IG when compared with AC air bubble of 10 and 30 mm Hg that was sustained for 1 hour (P < 0.05). Furthermore, corneal surface massage did not facilitate DSAEK graft adhesion (P = 0.59). Finally, paracentral venting incisions followed by interface fluid aspiration seemed to significantly decrease the IG (P = 0.014). Corneal venting incisions and higher AC IOP values seem to facilitate DSAEK donor graft lenticle adhesion to the recipient cornea.

  17. Mechanics of cell adhesion a materials science approach

    NASA Astrophysics Data System (ADS)

    Raz-Ben Aroush, Dikla

    Live cells are constantly exposed to mechanical forces induced by different physical interactions. One manner by which mechanical forces are sensed by cells is through cell-substrate contacts called focal adhesion (FA) sites associated with the termini of actin stress fibers. These forces play significant roles in many different cell functions. This area of research is currently the subject of extensive experimental and theoretical research, because the physical mechanisms involved in cell mechanics processes are still far from being understood. In the present study we borrow theoretical and experimental tools from the materials science field to further understand the physical mechanisms involved in cell response to mechanical signals. First, force transfer at cell-substrate adhesion sites (FA sites) was investigated by using a shear-lag type mechanical model classically used in composite material science. The shear stress profile produced along the cell-substrate interface was calculated and analyzed as a function of various material and geometrical characteristics of the adhesion region. It was found that at the front edge of the FA site there is a maximal shear stress. The full shape of the shear stress profile along the cell-substrate interface suggests a likely mechanism for the biochemical feedback activity leading to the growth of the adhesion region. Second, we studied how the shear stress profile varies during the temporal evolution of a single FA site, which was monitored and analyzed in detail for the first time using time-lapse video microscopy of rat embryonic fibroblasts. From image analysis of FA temporal evolution, it was found that single FA sites exhibit a consistent, recurring pattern of growth and saturation modes. On the contrary, disassembly mode of single FA sites exhibits an erratic behavior. Based on these results, the shear stress profiles were calculated at each step of the FA evolution process, and new aspects of a mechano

  18. αE-catenin regulates actin dynamics independently of cadherin-mediated cell–cell adhesion

    PubMed Central

    Benjamin, Jacqueline M.; Kwiatkowski, Adam V.; Yang, Changsong; Korobova, Farida; Pokutta, Sabine; Svitkina, Tatyana

    2010-01-01

    αE-catenin binds the cell–cell adhesion complex of E-cadherin and β-catenin (β-cat) and regulates filamentous actin (F-actin) dynamics. In vitro, binding of αE-catenin to the E-cadherin–β-cat complex lowers αE-catenin affinity for F-actin, and αE-catenin alone can bind F-actin and inhibit Arp2/3 complex–mediated actin polymerization. In cells, to test whether αE-catenin regulates actin dynamics independently of the cadherin complex, the cytosolic αE-catenin pool was sequestered to mitochondria without affecting overall levels of αE-catenin or the cadherin–catenin complex. Sequestering cytosolic αE-catenin to mitochondria alters lamellipodia architecture and increases membrane dynamics and cell migration without affecting cell–cell adhesion. In contrast, sequestration of cytosolic αE-catenin to the plasma membrane reduces membrane dynamics. These results demonstrate that the cytosolic pool of αE-catenin regulates actin dynamics independently of cell–cell adhesion. PMID:20404114

  19. The effect of plasma-nitrided titanium surfaces on osteoblastic cell adhesion, proliferation, and differentiation.

    PubMed

    Ferraz, Emanuela P; Sa, Juliana C; de Oliveira, Paulo T; Alves, Clodomiro; Beloti, Marcio M; Rosa, Adalberto L

    2014-04-01

    In this study, we evaluated the effect of new plasma-nitrided Ti surfaces on the progression of osteoblast cultures, including cell adhesion, proliferation and differentiation. Ti surfaces were treated using two plasma-nitriding protocols, hollow cathode for 3 h (HC 3 h) and 1 h (HC 1 h) and planar for 1 h. Untreated Ti surfaces were used as control. Cells derived from human alveolar and rat calvarial bones were cultured on Ti surfaces for periods of up to 14 days and the following parameters were evaluated: cell morphology, adhesion, spreading and proliferation, alkaline phosphatase (ALP) activity, extracellular matrix mineralization, and gene expression of key osteoblast markers. Plasma-nitriding treatments resulted in Ti surfaces with distinct physicochemical characteristics. The cell adhesion and ALP activity were higher on plasma-nitrided Ti surfaces compared with untreated one, whereas cell proliferation and extracellular matrix mineralization were not affected by the treatments. In addition, the plasma-nitrided Ti surfaces increased the ALP, reduced the osteocalcin and did not affect the Runx2 gene expression. We have shown that HC 3 h and planar Ti surfaces slightly favored the osteoblast differentiation process, and then these surfaces should be considered for further investigation using preclinical models. Copyright © 2013 Wiley Periodicals, Inc.

  20. Dystrophin Dp71f associates with the beta1-integrin adhesion complex to modulate PC12 cell adhesion

    PubMed Central

    Cerna, Joel; Cerecedo, Doris; Ortega, Arturo; García-Sierra, Francisco; Centeno, Federico; Garrido, Efrain; Mornet, Dominique; Cisneros, Bulmaro

    2006-01-01

    Dystrophin Dp71 is the main product of the Duchenne muscular dystrophy gene in the brain; however, its function is unknown. To study the role of Dp71 in neuronal cells, we previously generated by antisense treatment PC12 neuronal cell clones with decreased Dp71 expression (antisense-Dp71 cells). PC12 cells express two different splicing isoforms of Dp71, a cytoplasmic variant called Dp71f and a nuclear isoform called Dp71d. We previously reported that antisense-Dp71 cells display deficient adhesion to substrate and reduced immunostaining of β1-integrin in the cell area contacting the substrate. In this study, we isolated additional antisenseDp71 clones to analyze in detail the potential involvement of Dp71f isoform with the β1-integrin adhesion system of PC12 cells. Immunofluorescence analyses as well as immunoprecipitation assays demonstrated that the PC12 cell β1-integrin adhesion complex is composed of β1-integrin, talin, paxillin, α-actinin, FAK and actin. In addition, our results showed that Dp71f associates with most of the β1-integrin complex components (β1-integrin, FAK, α-actinin, talin and actin). In the antisense-Dp71 cells, the deficiency of Dp71 provokes a significant reduction of the β1-integrin adhesion complex and, consequently, the deficient adhesion of these cells to laminin. In vitro binding experiments confirmed the interaction of Dp71f with FAK and β1-integrin. Our data indicate that Dp71f is a structural component of the β1-integrin adhesion complex of PC12 cells that modulates PC12 cell adhesion by conferring proper complex assembly and/or maintenance. PMID:16935300

  1. Anandamide inhibits adhesion and migration of breast cancer cells

    SciTech Connect

    Grimaldi, Claudia; Pisanti, Simona; Laezza, Chiara; Malfitano, Anna Maria; Santoro, Antonietta; Vitale, Mario; Caruso, Maria Gabriella; Notarnicola, Maria; Iacuzzo, Irma; Portella, Giuseppe; Di Marzo, Vincenzo . E-mail: vdimarzo@icmib.na.cnr.it; Bifulco, Maurizio . E-mail: maubiful@unina.it

    2006-02-15

    The endocannabinoid system regulates cell proliferation in human breast cancer cells. We reasoned that stimulation of cannabinoid CB{sub 1} receptors could induce a non-invasive phenotype in breast mtastatic cells. In a model of metastatic spreading in vivo, the metabolically stable anandamide analogue, 2-methyl-2'-F-anandamide (Met-F-AEA), significantly reduced the number and dimension of metastatic nodes, this effect being antagonized by the selective CB{sub 1} antagonist SR141716A. In MDA-MB-231 cells, a highly invasive human breast cancer cell line, and in TSA-E1 cells, a murine breast cancer cell line, Met-F-AEA inhibited adhesion and migration on type IV collagen in vitro without modifying integrin expression: both these effects were antagonized by SR141716A. In order to understand the molecular mechanism involved in these processes, we analyzed the phosphorylation of FAK and Src, two tyrosine kinases involved in migration and adhesion. In Met-F-AEA-treated cells, we observed a decreased tyrosine phosphorylation of both FAK and Src, this effect being attenuated by SR141716A. We propose that CB{sub 1} receptor agonists inhibit tumor cell invasion and metastasis by modulating FAK phosphorylation, and that CB{sub 1} receptor activation might represent a novel therapeutic strategy to slow down the growth of breast carcinoma and to inhibit its metastatic diffusion in vivo.

  2. Adhesion of pancreatic beta cells to biopolymer films.

    PubMed

    Williams, S Janette; Wang, Qun; Macgregor, Ronal R; Siahaan, Teruna J; Stehno-Bittel, Lisa; Berkland, Cory

    2009-08-01

    Dramatic reversal of Type 1 diabetes in patients receiving pancreatic islet transplants continues to prompt vigorous research concerning the basic mechanisms underlying patient turnaround. At the most fundamental level, transplanted islets must maintain viability and function in vitro and in vivo and should be protected from host immune rejection. Our previous reports showed enhancement of islet viability and insulin secretion per tissue mass for small islets (<125 mum) as compared with large islets (>125 mum), thus, demonstrating the effect of enhancing the mass transport of islets (i.e. increasing tissue surface area to volume ratio). Here, we report the facile dispersion of rat islets into individual cells that are layered onto the surface of a biopolymer film towards the ultimate goal of improving mass transport in islet tissue. The tightly packed structure of intact islets was disrupted by incubating in calcium-free media resulting in fragmented islets, which were further dispersed into individual or small groups of cells by using a low concentration of papain. The dispersed cells were screened for adhesion to a range of biopolymers and the nature of cell adhesion was characterized for selected groups by quantifying adherent cells, measuring the surface area coverage of the cells, and immunolabeling cells for adhesion proteins interacting with selected biopolymers. Finally, beta cells in suspension were centrifuged to form controlled numbers of cell layers on films for future work determining the mass transport limitations in the adhered tissue constructs. (c) 2009 Wiley Periodicals, Inc. Biopolymers 91: 676-685, 2009.This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com.

  3. The Misregulation of Cell Adhesion Components during Tumorigenesis: Overview and Commentary

    PubMed Central

    Andl, Claudia D.

    2010-01-01

    Cell adhesion complexes facilitate attachment between cells or the binding of cells to the extracellular matrix. The regulation of cell adhesion is an important step in embryonic development and contributes to tissue homeostasis allowing processes such as differentiation and cell migration. Many mechanisms of cancer progression are reminiscent of embryonic development, for example, epithelial-mesenchymal transition, and involve the disruption of cell adhesion and expression changes in components of cell adhesion structures. Tight junctions, adherens junctions, desmosomes, and focal adhesion besides their roles in cell-cell or cell-matrix interaction also possess cell signaling function. Perturbations of such signaling pathways can lead to cancer. This article gives an overview of the common structures of cell adhesion and summarizes the impact of their loss on cancer development and progression with articles highlighted from the present issue. PMID:20953359

  4. Rutin inhibits proliferation, attenuates superoxide production and decreases adhesion and migration of human cancerous cells.

    PubMed

    Ben Sghaier, Mohamed; Pagano, Alessandra; Mousslim, Mohamed; Ammari, Youssef; Kovacic, Hervé; Luis, José

    2016-12-01

    Lung and colorectal cancer are the principal causes of death in the world. Rutin, an active flavonoid compound, is known for possessing a wide range of biological activities. In this study, we examined the effect of rutin on the viability, superoxide anion production, adhesion and migration of human lung (A549) and colon (HT29 and Caco-2) cancer cell lines. In order to control the harmlessness of the tested concentrations of rutin, the viability of cancer cell lines was assessed using a 3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. ROS generation was measured by lucigenin chemiluminescence detecting superoxide ions. To investigate the effect of rutin on the behavior of human lung and colon cancer cell lines, we performed adhesion assays, using various purified extracellular matrix (ECM) proteins. Finally, in vitro cell migration assays were explored using modified Boyden chambers. The viability of cancerous cells was inhibited by rutin. It also significantly attenuated the superoxide production in HT29 cells. In addition, rutin affected adhesion and migration of A549 and HT29 cell. These findings indicate that rutin, a natural molecule, might have potential as anticancer agent against lung and colorectal carcinogenesis.

  5. Fluorescence-based assays for in vitro analysis of cell adhesion and migration.

    PubMed

    Spessotto, Paola; Lacrima, Katia; Nicolosi, Pier Andrea; Pivetta, Eliana; Scapolan, Martina; Perris, Roberto

    2009-01-01

    Cell adhesion and cell migration are two primary cellular phenomena for which in vitro approaches may be exploited to effectively dissect the individual events and underlying molecular mechanisms. The use of assays dedicated to the analysis of cell adhesion and migration in vitro also afford an efficient way of conducting larger basic and applied research screenings on the factors affecting these processes and are potentially exploitable in the context of routine diagnostic, prognostic, and predictive tests in the biological and medical fields. Therefore, there is a longstanding continuum in the interest in devising more rationale such assays and major contributions in this direction have been provided by the advent of procedures based on fluorescence cell tagging, the design of instruments capable of detecting fluorescent signals with high sensitivity, and informatic tools allowing sophisticated elaboration of data generated through these instruments. In this report, we describe three representative fluorescence-based model assays for the qualitative and quantitative assessment of cell adhesion and cell locomotion in static and dynamic conditions. The assays are easily performed, accurate and reproducible, and can be automated for high-to-medium throughput screenings of cell behavior in vitro. Performance of the assays involves the use of certain dedicated disposable accessories, which are commercially available, and a few instruments that, due to their versatility, can be regarded as constituents of a more generic laboratory setup.

  6. Vasostatin-2 inhibits cell proliferation and adhesion in vascular smooth muscle cells, which are associated with the progression of atherosclerosis

    SciTech Connect

    Hou, Jianghong; Xue, Xiaolin; Li, Junnong

    2016-01-22

    Recently, the serum expression level of vasostatin-2 was found to be reduced and is being studied as an important indicator to assess the presence and severity of coronary artery disease; the functional properties of vasostatin-2 and its relationship with the development of atherosclerosis remains unclear. In this study, we attempted to detect the expression of vasostatin-2 and its impact on human vascular smooth muscle cells (VSMCs). Quantitative real-time PCR (qRT-PCR) and western blot were used to assess the expression level of vasostatin-2 in VSMCs between those from atherosclerosis and disease-free donors; we found that vasostatin-2 was significantly down-regulated in atherosclerosis patient tissues and cell lines. In addition, the over-expression of vasostatin-2 apparently inhibits cell proliferation and migration in VSMCs. Gain-of-function in vitro experiments further show that vasostatin-2 over-expression significantly inhibits inflammatory cytokines release in VSMCs. In addition, cell adhesion experimental analysis showed that soluble adhesion molecules (sICAM-1, sVCAM-1) had decreased expression when vasostatin-2 was over-expressed in VSMCs. Therefore, our results indicate that vasostatin-2 is an atherosclerosis-related factor that can inhibit cell proliferation, inflammatory response and cell adhesion in VSMCs. Taken together, our results indicate that vasostatin-2 could serve as a potential diagnostic biomarker and therapeutic option for human atherosclerosis in the near future. - Highlights: • Vasostatin-2 levels were down-regulated in atherosclerosis patient tissues and VSMCs. • Ectopic expression of vasostatin-2 directly affects cell proliferation and migration in vitro. • Ectopic expression of vasostatin-2 protein affects pro-inflammatory cytokines release in VSMCs. • Ectopic expression of vasostatin-2 protein affects cell adhesion in VSMCs.

  7. Activation of the canonical Wnt/{beta}-catenin pathway enhances monocyte adhesion to endothelial cells

    SciTech Connect

    Lee, Dong Kun . E-mail: leedk@memorialhealthsource.com; Nathan Grantham, R.; Trachte, Aaron L.; Mannion, John D.; Wilson, Colleen L.

    2006-08-18

    Monocyte adhesion to vascular endothelium has been reported to be one of the early processes in the development of atherosclerosis. In an attempt to develop strategies to prevent or delay atherosclerosis progression, we analyzed effects of the Wnt/{beta}-catenin signaling pathway on monocyte adhesion to various human endothelial cells. Adhesion of fluorescein-labeled monocytes to various human endothelial cells was analyzed under a fluorescent microscope. Unlike sodium chloride, lithium chloride enhanced monocyte adhesion to endothelial cells in a dose-dependent manner. We further demonstrated that inhibitors for glycogen synthase kinase (GSK)-3{beta} or proteosome enhanced monocyte-endothelial cell adhesion. Results of semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) indicated that activation of Wnt/{beta}-catenin pathway did not change expression levels of mRNA for adhesion molecules. In conclusion, the canonical Wnt/{beta}-catenin pathway enhanced monocyte-endothelial cell adhesion without changing expression levels of adhesion molecules.

  8. Evaluating fundamental position-dependent differences in wood cell wall adhesion using nanoindentation.

    PubMed

    Obersriebnig, Michael; Konnerth, Johannes; Gindl-Altmutter, Wolfgang

    2013-01-01

    Spruce wood specimens were bonded with one-component polyurethane (PUR) and urea-formaldehyde (UF) adhesive, respectively. The adhesion of the adhesives to the wood cell wall was evaluated at two different locations by means of a new micromechanical assay based on nanoindentation. One location tested corresponded to the interface between the adhesive and the natural inner cell wall surface of the secondary cell wall layer 3 (S3), whereas the second location corresponded to the interface between the adhesive and the freshly cut secondary cell wall layer 2 (S2). Overall, a trend towards reduced cell wall adhesion was found for PUR compared to UF. Position-resolved examination revealed excellent adhesion of UF to freshly cut cell walls (S2) but significantly diminished adhesion to the inner cell wall surface (S3). In contrast, PUR showed better adhesion to the inner cell wall surface and less adhesion to freshly cut cell walls. Atomic force microscopy revealed a less polar character for the inner cell wall surface (S3) compared to freshly cut cell walls (S2). It is proposed that differences in the polarity of the used adhesives and the surface chemistry of the two cell wall surfaces examined account for the observed trends.

  9. Expression of cell adhesion complexes in epithelial cells seeded on biomaterial surfaces.

    PubMed

    Räisänen, L; Könönen, M; Juhanoja, J; Varpavaara, P; Hautaniemi, J; Kivilahti, J; Hormia, M

    2000-01-01

    Clinical studies indicate that soft tissue responses around dental implants vary, depending on the material used. It is therefore also possible that there are differences in how epithelial cells attach to various biomaterial surfaces. We studied the adhesion of cultured epithelial cells to five different dental material surfaces and to glass. The efficacy of adhesion was evaluated by using scanning electron microscopy (SEM) and immunofluorescence microscopy (IF) with antibodies to vinculin and alpha(6)beta(4) integrin, two cell surface molecules that are functional in epithelial cell adhesion. Our results indicate that epithelial cells adhere and spread more avidly on metallic surfaces (titanium, Ti(6)Al(4)V titanium alloy, dental gold alloy) than on ceramic surfaces (dental porcelain, aluminum oxide). As revealed by SEM, cells on metallic surfaces had a flattened morphology and formed multicellular islands. On porcelain and aluminum oxide most cells were round and adhesion occurred as single cells. Surface coverage was over twofold on metallic surfaces as compared to ceramic surfaces. IF of cells grown on metallic surfaces revealed vinculin in well-organized focal contacts and alpha(6)beta(4) integrin in punctate patterns typical of prehemidesmosomes. On porcelain and aluminum oxide surfaces the cells were mostly round and showed less well-organized adhesion complexes. Our results indicate that smooth metallic biomaterial surfaces are optimal for epithelial cell adhesion and spreading. These findings may have clinical implications in the design of transgingival implant structures. Copyright 2000 John Wiley & Sons, Inc.

  10. Strong adhesion by regulatory T cells induces dendritic cell cytoskeletal polarization and contact-dependent lethargy

    PubMed Central

    Mucsi, Ashley D.; Meng, Junchen; Yan, Jiacong; Zhang, Zongde; Wu, Mei; Hari, Aswin; Stenner, Melanie D.; Zheng, Wencheng; Kubes, Paul; Xia, Tie; Amrein, Matthias W.

    2017-01-01

    Dendritic cells are targeted by regulatory T (T reg) cells, in a manner that operates as an indirect mode of T cell suppression. In this study, using a combination of single-cell force spectroscopy and structured illumination microscopy, we analyze individual T reg cell–DC interaction events and show that T reg cells exhibit strong intrinsic adhesiveness to DCs. This increased DC adhesion reduces the ability of contacted DCs to engage other antigen-specific cells. We show that this unusually strong LFA-1–dependent adhesiveness of T reg cells is caused in part by their low calpain activities, which normally release integrin–cytoskeleton linkage, and thereby reduce adhesion. Super resolution imaging reveals that such T reg cell adhesion causes sequestration of Fascin-1, an actin-bundling protein essential for immunological synapse formation, and skews Fascin-1–dependent actin polarization in DCs toward the T reg cell adhesion zone. Although it is reversible upon T reg cell disengagement, this sequestration of essential cytoskeletal components causes a lethargic state of DCs, leading to reduced T cell priming. Our results reveal a dynamic cytoskeletal component underlying T reg cell–mediated DC suppression in a contact-dependent manner. PMID:28082358

  11. Lateral adhesion drives reintegration of misplaced cells into epithelial monolayers

    PubMed Central

    St Johnston, Daniel

    2016-01-01

    Cells in simple epithelia orient their mitotic spindles in the plane of the epithelium so that both daughter cells are born within the epithelial sheet. This is assumed to be important to maintain epithelial integrity and prevent hyperplasia, because misaligned divisions give rise to cells outside the epithelium1,2. Here we test this assumption in three types of Drosophila epithelia; the cuboidal follicle epithelium, the columnar early embryonic ectoderm, and the pseudostratified neuroepithelium. Ectopic expression of Inscuteable in these tissues reorients mitotic spindles, resulting in one daughter cell being born outside of the epithelial layer. Live imaging reveals that these misplaced cells reintegrate into the tissue. Reducing the levels of the lateral homophilic adhesion molecules Neuroglian or Fasciclin 2 disrupts reintegration, giving rise to extra-epithelial cells, whereas disruption of adherens junctions has no effect. Thus, the reinsertion of misplaced cells appears to be driven by lateral adhesion, which pulls cells born outside the epithelia layer back into it. Our findings reveal a robust mechanism that protects epithelia against the consequences of misoriented divisions. PMID:26414404

  12. Class A scavenger receptor-mediated cell adhesion requires the sequential activation of Lyn and PI3-kinase.

    PubMed

    Nikolic, Dejan M; Cholewa, Jill; Gass, Cecelia; Gong, Ming C; Post, Steven R

    2007-04-01

    Class A scavenger receptors (SR-A) participate in multiple macrophage functions including macrophage adhesion to modified proteins. SR-A-mediated adhesion may therefore contribute to chronic inflammation by promoting macrophage accumulation at sites of protein modification. The mechanisms that couple SR-A binding to modified proteins with increased cell adhesion have not been defined. In this study, SR-A expressing HEK cells and SR-A+/+ or SR-A-/- macrophages were used to delineate the signaling pathways required for SR-A-mediated adhesion to modified protein. Inhibiting G(i/o) activation, which decreases initial SR-A-mediated cell attachment, did not prevent the subsequent spreading of attached cells. In contrast, inhibition of Src kinases or PI3-kinase abolished SR-A-dependent cell spreading without affecting SR-A-mediated cell attachment. Consistent with these results, the Src kinase Lyn and PI3-kinase were sequentially activated during SR-A-mediated cell spreading. Furthermore, activation of both Lyn and PI3-kinase was required for enhancing paxillin phosphorylation. Activation of a Src kinase-PI3-kinase-Akt pathway was also observed in cells expressing a truncated SR-A protein that does not internalize indicating that SR-A-mediated activation of intracellular signaling cascades following adhesion to MDA-BSA is independent of receptor internalization. Thus SR-A binding to modified protein activates signaling cascades that have distinct roles in regulating initial cell attachment and subsequent cell spreading.

  13. Mathematical modeling of cell adhesion in shear flow: application to targeted drug delivery in inflammation and cancer metastasis.

    PubMed

    Jadhav, Sameer; Eggleton, Charles D; Konstantopoulos, Konstantinos

    2007-01-01

    Cell adhesion plays a pivotal role in diverse biological processes that occur in the dynamic setting of the vasculature, including inflammation and cancer metastasis. Although complex, the naturally occurring processes that have evolved to allow for cell adhesion in the vasculature can be exploited to direct drug carriers to targeted cells and tissues. Fluid (blood) flow influences cell adhesion at the mesoscale by affecting the mechanical response of cell membrane, the intercellular contact area and collisional frequency, and at the nanoscale level by modulating the kinetics and mechanics of receptor-ligand interactions. Consequently, elucidating the molecular and biophysical nature of cell adhesion requires a multidisciplinary approach involving the synthesis of fundamentals from hydrodynamic flow, molecular kinetics and cell mechanics with biochemistry/molecular cell biology. To date, significant advances have been made in the identification and characterization of the critical cell adhesion molecules involved in inflammatory disorders, and, to a lesser degree, in cancer metastasis. Experimental work at the nanoscale level to determine the lifetime, interaction distance and strain responses of adhesion receptor-ligand bonds has been spurred by the advent of atomic force microscopy and biomolecular force probes, although our current knowledge in this area is far from complete. Micropipette aspiration assays along with theoretical frameworks have provided vital information on cell mechanics. Progress in each of the aforementioned research areas is key to the development of mathematical models of cell adhesion that incorporate the appropriate biological, kinetic and mechanical parameters that would lead to reliable qualitative and quantitative predictions. These multiscale mathematical models can be employed to predict optimal drug carrier-cell binding through isolated parameter studies and engineering optimization schemes, which will be essential for developing

  14. A new strategy to measure intercellular adhesion forces in mature cell-cell contacts

    PubMed Central

    Sancho, Ana; Vandersmissen, Ine; Craps, Sander; Luttun, Aernout; Groll, Jürgen

    2017-01-01

    Intercellular adhesion plays a major role in tissue development and homeostasis. Yet, technologies to measure mature cell-cell contacts are not available. We introduce a methodology based on fluidic probe force microscopy to assess cell-cell adhesion forces after formation of mature intercellular contacts in cell monolayers. With this method we quantify that L929 fibroblasts exhibit negligible cell-cell adhesion in monolayers whereas human endothelial cells from the umbilical artery (HUAECs) exert strong intercellular adhesion forces per cell. We use a new in vitro model based on the overexpression of Muscle Segment Homeobox 1 (MSX1) to induce Endothelial-to-Mesenchymal Transition (EndMT), a process involved in cardiovascular development and disease. We reveal how intercellular adhesion forces in monolayer decrease significantly at an early stage of EndMT and we show that cells undergo stiffening and flattening at this stage. This new biomechanical insight complements and expands the established standard biomolecular analyses. Our study thus introduces a novel tool for the assessment of mature intercellular adhesion forces in a physiological setting that will be of relevance to biological processes in developmental biology, tissue regeneration and diseases like cancer and fibrosis. PMID:28393890

  15. Adhesion and internalization differences of COM nanocrystals on Vero cells before and after cell damage.

    PubMed

    Gan, Qiong-Zhi; Sun, Xin-Yuan; Ouyang, Jian-Ming

    2016-02-01

    The adhesion and internalization between African green monkey kidney epithelial (Vero) cells (before and after oxidative damage by hydrogen peroxide) and calcium oxalate monohydrate (COM) nanocrystals (97±35nm) were investigated so as to discuss the molecular and cellular mechanism of kidney stone formation. Scanning electron microscope (SEM) was used to observe the Vero-COM nanocrystal adhesion; the nanocrystal-cell adhesion was evaluated by measuring the content of malonaldehyde (MDA), the activity of superoxide dismutase (SOD), the expression level of cell surface osteopontin (OPN) and the change of Zeta potential. Confocal microscopy and flow cytometry were used for the observation and quantitative analysis of crystal internalization. In the process of adhesion, the cell viability and the SOD activity declined, the MDA content, Zeta potential, and the OPN expression level increased. The adhesive capacity of injured Vero was obviously stronger than normal cells; in addition the injured cells promoted the aggregation of COM nanocrystals. The capacity of normal cells to internalize crystals was obviously stronger than that of injured cells. Cell injury increased adhesive sites on cell surface, thereby facilitating the aggregation of COM nanocrystals and their attachment, which results in enhanced risk of calcium oxalate stone formation.

  16. Polyelectrolytes Multilayers to Modulate Cell Adhesion: A Study of the Influence of Film Composition and Polyelectrolyte Interdigitation on the Adhesion of the A549 Cell Line.

    PubMed

    Muzzio, Nicolás E; Pasquale, Miguel A; Gregurec, Danijela; Diamanti, Eleftheria; Kosutic, Marija; Azzaroni, Omar; Moya, Sergio E

    2016-04-01

    Polyelectrolyte multilayers (PEMs) with different polycation/polyanion pairs are fabricated by the layer-by-layer technique employing synthetic, natural, and both types of polyelectrolytes. The impact of the chemical composition of PEMs on cell adhesion is assessed by studying cell shape, spreading area, focal contacts, and cell proliferation for the A549 cell line. Cells exhibit good adhesion on PEMs containing natural polycations and poly(sodium 4-styrenesulfonate) (PSS) as polyanion, but limited adhesion is observed on PEMs fabricated from both natural polyelectrolytes. PEMs are then assembled, depositing a block of natural polyelectrolytes on top of a stiffer block with PSS as polyanion. Cell adhesion is enhanced on top of the diblock PEMs compared to purely natural PEMs. This fact could be explained by the interdigitation between polyelectrolytes from the two blocks. Diblock PEM assembly provides a simple means to tune cell adhesion on biocompatible PEMs.

  17. Enhanced cell viability and cell adhesion using low conductivity medium for negative dielectrophoretic cell patterning.

    PubMed

    Puttaswamy, Srinivasu Valagerahally; Sivashankar, Shilpa; Chen, Rong-Jhe; Chin, Chung-Kuang; Chang, Hwan-You; Liu, Cheng Hsien

    2010-10-01

    Negative dielectrophoretic (n-DEP) cell manipulation is an efficient way to pattern human liver cells on micro-electrode arrays. Maintaining cell viability is an important objective for this approach. This study investigates the effect of low conductivity medium and the optimally designed microchip on cell viability and cell adhesion. To explore the influence of conductivity on cell viability and cell adhesion, we have used earlier reported dielectrophoresis (DEP) buffer with a conductivity of 10.2 mS/m and three formulated media with conductivity of 9.02 (M1), 8.14 (M2), 9.55 (M3) mS/m. The earlier reported isotonic sucrose/dextrose buffer (DEP buffer) used for DEP manipulation has the drawback of poor cell adhesion and cell viability. A microchip prototype with well-defined positioning of titanium electrode arrays was designed and fabricated on a glass substrate. The gap between the radial electrodes was accurately determined to achieve good cell patterning performance. Parameters such as dimension of positioning electrode, amplitude, and frequency of voltage signal were investigated to optimize the performance of the microchip.

  18. How geometric details can affect the strength of adhesive lap joints

    SciTech Connect

    Metzinger, K.E.; Guess, T.R.

    1996-12-31

    The durability of adhesively bonded joints--when utilized as blade attachments--has a significant impact on the performance of wind turbines. Accordingly, there is interest in determining how geometric details affect the strength of these joints. Finite element analyses were performed to aid in the selection of three composite-to-metal joint geometries for compressive axial testing. Both monotonic and low-cycle fatigue tests were conducted. Analysis and testing of these joints provide insight into the effects of adding extra adhesive to the end of the bond or tapering the metal adherend. The issue of whether the relative performance of different joints in monotonic tests can be used to predict the relative fatigue strength of these joints is also addressed.

  19. Polystyrene Nanoparticles Activate Erythrocyte Aggregation and Adhesion to Endothelial Cells.

    PubMed

    Barshtein, Gregory; Livshits, Leonid; Shvartsman, Leonid D; Shlomai, Noa Ofek; Yedgar, Saul; Arbell, Dan

    2016-03-01

    Nanoparticles (NPs) are drawing an increasing clinical interest because of their potential use as drug carriers. Recently, a new strategy for elevation of NPs in vivo circulation time has been proposed, specifically, utilizing red blood cells (RBCs) as a carrier for NPs, that are loaded with a drug, by interaction (in vitro) of human RBCs with NPs (RBCNP). This class of delivery set-up, combines advantages of natural RBCs and synthetic biomaterials. Previous studies demonstrated that NPs initiated hemolysis of RBC and activated cells aggregation. In the present study, we examined the effect of RBCNP on the aggregation of RBC and their adhesion to endothelial cells (EC). Red cells were treated with polystyrene NPs (PS-NP), and following their washing, were added to suspension of untreated cells at various concentrations. We observed that the PS-NP and RBCNP initiated the formation of red cells aggregates and markedly elevated RBC adhesion to EC. These effects were augmented with (a) increasing concentration of NPs or RBCNP, and (b) with decreasing NP size. This implies that RBCNP are cells with a stronger intercellular interaction, and may thereby induce the formation of large and strong aggregates with untreated RBC, as well as strong RBC/EC interaction.

  20. Evidence for cell adhesion-mediated drug resistance of multiple myeloma cells in vivo.

    PubMed

    Schmidmaier, R; Mörsdorf, K; Baumann, P; Emmerich, B; Meinhardt, G

    2006-01-01

    Multiple myeloma is an incurable disease and patients eventually die of disease progression due to drug resistance. VLA-4 (very late antigen 4), VCAM (vascular adhesion molecule), LFA-1 (leukocyte function-associated antigen 1), and ICAM-1 (intercellular adhesion molecule 1)-mediated adhesion of myeloma cells to bone marrow stromal cells induces primary multidrug resistance in vitro. Based on these preclinical data we hypothesized that myeloma cells with strong adhesion - due to strong expression of adhesion molecules on the cell surface - are selected by chemotherapy in patients. To prove this hypothesis we determined the expression levels of adhesion molecules in 31 multiple myeloma patients by flow cytometry. A 3-color stain with CD38, CD138 and antibodies against VLA-4, ICAM-1, LFA-1, and VCAM was performed. The patients were either at diagnosis (chemo-naive; n=17) or at relapse (pre-treated; n=15). Furthermore, the response to the next chemotherapy of chemo-naive patients was correlated with the expression levels of adhesion molecules. ICAM-1, VLA-4, and VCAM expression was higher in pre-treated patients than in chemo-naive patients and the expression levels increased with the number of chemotherapy regimens. Primarily multidrug-resistant patients had significantly higher expression levels of VLA-4 and ICAM-1 than responders. This study suggests that multiple myeloma cells expressing high levels of VLA-4 and ICAM-1 are drug resistant and that such a subpopulation of cells is selected by chemotherapy.

  1. Regulation of cell-cell adhesion of MDCK cells by Cdc42 and Rac1 small GTPases.

    PubMed

    Kuroda, S; Fukata, M; Fujii, K; Nakamura, T; Izawa, I; Kaibuchi, K

    1997-11-17

    Rac1, a member of the Rho small GTPases family, has recently been shown to be involved in the regulation of cell-cell adhesion mediated by cadherin. Here we showed that Cdc42, another member of Rho family, accumulated at cell-cell contact sites. Microinjection of Rho GDI, a negative regulator of the Rho family members, into Madin-Darby canine kidney (MDCK) cells resulted in perturbation of epithelial cell morphology and of cell-cell and cell-substratum adhesions, and comicroinjection of dominant active Cdc42 or Rac1 reversed the action of Rho GDI, suggesting that the active form of Cdc42 or Rac1 is required for maintaining the cell-cell and cell-substratum adhesions. These observations suggest that Cdc42, in addition to Rac1, can regulate the cell-cell adhesion.

  2. Implication of an outer surface lipoprotein in adhesion of Bifidobacterium bifidum to Caco-2 cells.

    PubMed

    Guglielmetti, Simone; Tamagnini, Isabella; Mora, Diego; Minuzzo, Mario; Scarafoni, Alessio; Arioli, Stefania; Hellman, Jukka; Karp, Matti; Parini, Carlo

    2008-08-01

    We found that the human intestinal isolate Bifidobacterium bifidum MIMBb75 strongly adhered to Caco-2 cells. Proteinase K and lithium chloride treatments showed that proteins play a key role in MIMBb75 adhesion to Caco-2 cells. By studying the cell wall-associated proteins, we identified a surface protein, which we labeled BopA. We purified the protein chromatographically and found that it functioned as an adhesion promoter on Caco-2 cells. In silico analysis of the gene coding for this protein and globomycin experiments showed that BopA is a cysteine-anchored lipoprotein expressed as a precursor polypeptide. A database search indicated that BopA appears to function biologically as an oligopeptide/tripeptide-solute-binding protein in the ABC transport system. We discovered a protein corresponding to BopA and its gene in eight other highly adherent B. bifidum strains. Finally, we found that B. bifidum MIMBb75 and BopA affected the production of interleukin-8 in Caco-2 epithelial cells. BopA is the first protein described to date to be directly involved in the adhesion of bifidobacteria to Caco-2 cells and to show immunomodulatory activity.

  3. Parallel Control over Surface Charge and Wettability Using Polyelectrolyte Architecture: Effect on Protein Adsorption and Cell Adhesion.

    PubMed

    Guo, Shanshan; Zhu, Xiaoying; Li, Min; Shi, Liya; Ong, June Lay Ting; Jańczewski, Dominik; Neoh, Koon Gee

    2016-11-09

    Surface charge and wettability, the two prominent physical factors governing protein adsorption and cell adhesion, have been extensively investigated in the literature. However, a comparison between these driving forces in terms of their independent and cooperative effects in affecting adhesion is rarely explored on a systematic and quantitative level. Herein, we formulate a protocol that features two-dimensional control over both surface charge and wettability with limited cross-parameter influence. This strategy is implemented by controlling both the polyion charge density in the layer-by-layer (LbL) assembly process and the polyion side-chain chemical structures. The 2D property matrix spans surface isoelectric points ranging from 5 to 9 and water contact angles from 35 to 70°, with other interferential factors (e.g., roughness) eliminated. The interplay between these two surface variables influences protein (bovine serum albumin, lysozyme) adsorption and 3T3 fibroblast cell adhesion. For proteins, we observe the presence of thresholds for surface wettability and electrostatic driving forces necessary to affect adhesion. Beyond these thresholds, the individual effects of electrostatic forces and wettability are observed. For fibroblast, both surface charge and wettability have an effect on its adhesion. The combined effects of positive charge and hydrophilicity lead to the highest cell adhesion, whereas negative charge and hydrophobicity lead to the lowest cell adhesion. Our design strategy can potentially form the basis for studying the distinct behaviors of electrostatic force or wettability driven interfacial phenomena and serve as a reference in future studies assessing protein adsorption and cell adhesion to surfaces with known charge and wettability within the property range studied here.

  4. Single-cell RNAseq reveals cell adhesion molecule profiles in electrophysiologically defined neurons

    PubMed Central

    Földy, Csaba; Darmanis, Spyros; Aoto, Jason; Malenka, Robert C.; Quake, Stephen R.; Südhof, Thomas C.

    2016-01-01

    In brain, signaling mediated by cell adhesion molecules defines the identity and functional properties of synapses. The specificity of presynaptic and postsynaptic interactions that is presumably mediated by cell adhesion molecules suggests that there exists a logic that could explain neuronal connectivity at the molecular level. Despite its importance, however, the nature of such logic is poorly understood, and even basic parameters, such as the number, identity, and single-cell expression profiles of candidate synaptic cell adhesion molecules, are not known. Here, we devised a comprehensive list of genes involved in cell adhesion, and used single-cell RNA sequencing (RNAseq) to analyze their expression in electrophysiologically defined interneurons and projection neurons. We compared the cell type-specific expression of these genes with that of genes involved in transmembrane ion conductances (i.e., channels), exocytosis, and rho/rac signaling, which regulates the actin cytoskeleton. Using these data, we identified two independent, developmentally regulated networks of interacting genes encoding molecules involved in cell adhesion, exocytosis, and signal transduction. Our approach provides a framework for a presumed cell adhesion and signaling code in neurons, enables correlating electrophysiological with molecular properties of neurons, and suggests avenues toward understanding synaptic specificity. PMID:27531958

  5. Single-cell RNAseq reveals cell adhesion molecule profiles in electrophysiologically defined neurons.

    PubMed

    Földy, Csaba; Darmanis, Spyros; Aoto, Jason; Malenka, Robert C; Quake, Stephen R; Südhof, Thomas C

    2016-08-30

    In brain, signaling mediated by cell adhesion molecules defines the identity and functional properties of synapses. The specificity of presynaptic and postsynaptic interactions that is presumably mediated by cell adhesion molecules suggests that there exists a logic that could explain neuronal connectivity at the molecular level. Despite its importance, however, the nature of such logic is poorly understood, and even basic parameters, such as the number, identity, and single-cell expression profiles of candidate synaptic cell adhesion molecules, are not known. Here, we devised a comprehensive list of genes involved in cell adhesion, and used single-cell RNA sequencing (RNAseq) to analyze their expression in electrophysiologically defined interneurons and projection neurons. We compared the cell type-specific expression of these genes with that of genes involved in transmembrane ion conductances (i.e., channels), exocytosis, and rho/rac signaling, which regulates the actin cytoskeleton. Using these data, we identified two independent, developmentally regulated networks of interacting genes encoding molecules involved in cell adhesion, exocytosis, and signal transduction. Our approach provides a framework for a presumed cell adhesion and signaling code in neurons, enables correlating electrophysiological with molecular properties of neurons, and suggests avenues toward understanding synaptic specificity.

  6. Timescales and Frequencies of Reversible and Irreversible Adhesion Events of Single Bacterial Cells.

    PubMed

    Hoffman, Michelle D; Zucker, Lauren I; Brown, Pamela J B; Kysela, David T; Brun, Yves V; Jacobson, Stephen C

    2015-12-15

    In the environment, most bacteria form surface-attached cell communities called biofilms. The attachment of single cells to surfaces involves an initial reversible stage typically mediated by surface structures such as flagella and pili, followed by a permanent adhesion stage usually mediated by polysaccharide adhesives. Here, we determine the absolute and relative timescales and frequencies of reversible and irreversible adhesion of single cells of the bacterium Caulobacter crescentus to a glass surface in a microfluidic device. We used fluorescence microscopy of C. crescentus expressing green fluorescent protein to track the swimming behavior of individual cells prior to adhesion, monitor the cell at the surface, and determine whether the cell reversibly or irreversibly adhered to the surface. A fluorescently labeled lectin that binds specifically to polar polysaccharides, termed holdfast, discriminated irreversible adhesion events from reversible adhesion events where no holdfast formed. In wild-type cells, the holdfast production time for irreversible adhesion events initiated by surface contact (23 s) was 30-times faster than the holdfast production time that occurs through developmental regulation (13 min). Irreversible adhesion events in wild-type cells (3.3 events/min) are 15-times more frequent than in pilus-minus mutant cells (0.2 events/min), indicating the pili are critical structures in the transition from reversible to irreversible surface-stimulated adhesion. In reversible adhesion events, the dwell time of cells at the surface before departing was the same for wild-type cells (12 s) and pilus-minus mutant cells (13 s), suggesting the pili do not play a significant role in reversible adhesion. Moreover, reversible adhesion events in wild-type cells (6.8 events/min) occur twice as frequently as irreversible adhesion events (3.3 events/min), demonstrating that most cells contact the surface multiple times before transitioning from reversible to

  7. Control of mesenchymal stem cell phenotype and differentiation depending on cell adhesion mechanism.

    PubMed

    Kang, J; Park, H M; Kim, Y W; Kim, Y H; Varghese, S; Seok, H K; Kim, Y G; Kim, S H

    2014-11-25

    Control of cell-matrix adhesion has become an important issue in the regulation of stem cell function. In this study, a maltose-binding protein (MBP)-linked basic fibroblast growth factor (FGF2)-immobilised polystyrene surface (PS-MBP-FGF2) was applied as an artificial matrix to regulate integrin-mediated signalling. We sought to characterise human mesenchymal-stem cell (hMSC) behaviour in response to two different mechanisms of cell adhesion; (i) FGF2-heparan sulphate proteoglycan (HSPG)-mediated adhesion vs. (ii) fibronectin (FN)-integrin-mediated adhesion. Heparin inhibited hMSC adhesion to PS-MBP-FGF2 but not to FN-coated surface. The phosphorylation of focal adhesion kinase, cytoskeletal re-organisation, and cell proliferation were restricted in hMSCs adhering to PS-MBP-FGF2 compared to FN-coated surface. Expression of MSC markers, such as CD105, CD90 and CD166, decreased in hMSCs expanded on PS-MBP-FGF2 compared to expression in cells expanded on FN-coated surface. hMSCs that were expanded on FN-coated surface differentiated into osteogenic and adipogenic cells more readily than those that were expanded on PS-MBP-FGF2. Furthermore, we characterised the N-linked glycan structures of hMSCs depending on the cell adhesion mechanism using mass spectrometry (MS)-based quantitative techniques. MS analysis revealed that 2,3-sialylated glycans, a potential marker of stem cell function, were more abundant on hMSCs expanded on FN-coated surface than on those expanded on PS-MBP-FGF2. Thus, the differentiation potential of hMSCs is controlled by the type of adhesion substrate that might provide an idea for the design of biomaterials to control stem cell fate. Elucidation of the glycan structure on the cell membrane may help characterise hMSC function.

  8. Self assembling bioactive materials for cell adhesion in tissue repair

    NASA Astrophysics Data System (ADS)

    Hwang, Julia J.

    This work involved the study of biodegradable and biocompatible materials that have the potential to modify tissue engineering scaffolds through self assembly, generating multiple layers that deliver bioactivity. Diblock biomaterials containing cholesteryl moieties and oligomers of lactic acid units were found to form single crystals when precipitated from hot ethanol and smectic liquid crystalline phases when cast as a film. Cell culture experiments on these films with 3T3 and 3T6 fibroblasts indicated that these ordered materials form surfaces with specific chemistries that favored cell adhesion, spreading, and proliferation suggesting the potential of mediating human tissue repair. The author believes the cholesteryl moieties found on the surface play a key role in determining cell behavior. Cholesteryl-(L-lactic acid) diblock molecules were then functionalized with moieties including vitamin Bx, cholesterol, and the anti-inflammatory drug indomethacin. An unstable activated ester between indomethacin and the diblock molecule resulted in the release of indomethacin into the culture medium which inhibited the proliferation of 3T3 fibroblasts. Finally, a series of molecules were designed to incorporate dendrons based on amino acids at the termini of the diblock structures. It was determined that lysine, a basic amino acid, covalently coupled to cholesteryl-(L-lactic acid) can promote cell adhesion and spreading while negatively charged and zwitterionic 2nd generation dendrons based on aspartic acid do not. Incorporation of the well known arginine-glycine-aspartic acid (RGD) sequence, which is found in many adhesive proteins, to the dendrons imparted integrin-mediated cell adhesion as evidenced by the formation of stress fibers. We also explored the capacity of integrin receptors to bind to ligands that are not the linear form of RGD, but have R, G, and D spatially positioned to mimic the linear RGD environments. For this purpose, the arms of the 2 nd generation

  9. Cell Adhesion and Growth on the Anodized Aluminum Oxide Membrane.

    PubMed

    Park, Jeong Su; Moon, Dalnim; Kim, Jin-Seok; Lee, Jin Seok

    2016-03-01

    Nanotopological cues are popular tools for in vivo investigation of the extracellular matrix (ECM) and cellular microenvironments. The ECM is composed of multiple components and generates a complex microenvironment. The development of accurate in vivo methods for the investigation of ECM are important for disease diagnosis and therapy, as well as for studies on cell behavior. Here, we fabricated anodized aluminum oxide (AAO) membranes using sulfuric and oxalic acid under controlled voltage and temperature. The membranes were designed to possess three different pore and interpore sizes, AAO-1, AAO-2, and AAO-3 membranes, respectively. These membranes were used as tools to investigate nanotopology-signal induced cell behavior. Cancerous cells, specifically, the OVCAR-8 cell-line, were cultured on porous AAO membranes and the effects of these membranes on cell shape, proliferation, and viability were studied. AAO-1 membranes bearing small sized pores were found to maintain the spreading shape of the cultured cells. Cells cultured on AAO-2 and AAO-3 membranes, bearing large pore-sized AAO membranes, changed shape from spreading to rounding. Furthermore, cellular area decreased when cells were cultured on all three AAO membranes that confirmed decreased levels of focal adhesion kinase (FAK). Additionally, OVCAR-8 cells exhibited increased proliferation on AAO membranes possessing various pore sizes, indicating the importance of the nanosurface structure in regulating cell behaviors, such as cell proliferation. Our results suggest that porous-AAO membranes induced nanosurface regulated cell behavior as focal adhesion altered the intracellular organization of the cytoskeleton. Our results may find potential applications as tools in in vivo cancer research studies.

  10. The application of flow cytophotometry in measurements of cell adhesion.

    PubMed

    Ostrowski, K; Watson, J V; Barnard, P J; Barnard, E A; Thomas, K; Freedman, L; de Stavola, B

    1986-01-01

    A common approach to the study of cell substrate interactions is the measurement of the attachment of cells to different substrates or to cultured cell layers. The evaluation of attachment is made either by scintillation counting of previously labelled adhering cells, or by light microscopy using the criterion of cell shape, sometimes refined by automatic image analysis. These methods have many drawbacks. This paper suggests the use of fluorescence-activated flow cytophotometry, (FC) which yields direct counts of the non-adhering cells. These "free" cells are removed after completion of the adhesion experiment from the microtitre plate wells. An internal standard, in the form of fluorescent polystyrene beads is added, allowing evaluation of the percentage of cells adhering to the well walls. Flow cytophotometry then produces data based on the analysis of large populations of cells. Unequivocal discrimination is obtained between the counted cells and counted fluorescent beads eliminating counting errors. The results can be processed on line by computer. A suspension of mouse splenocytes was used for the evaluation of the overall error of the method arising from inaccuracies in pipetting, interference of glutaraldehyde with ethidium bromide (EB) staining and instrumental error. Each adhesion experiment was terminated by staining and post-fixation and it was established that this introduces no change in cell counting, in comparison with the original unfixed cells. Prefixation, however, quenches the EB staining and would interfere with the counting procedure. The overall standard error of the technique was found to be 5%-10%.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Live-cell migration and adhesion turnover assays.

    PubMed

    Lacoste, J; Young, K; Brown, Claire M

    2013-01-01

    Fluorescence microscopy has revolutionized the way live-cell imaging is achieved. At the same time, it is also potentially harmful to a living specimen. Therefore, the specimen must be monitored for viability and health before, during, and after imaging sessions. Methods for monitoring cell viability and health will be discussed in this chapter. Another key to successful live-cell imaging is to minimize light exposure as much as possible. A summary of strategies for minimizing light exposure including maximizing the light throughput of the microscope and the sensitivity of light detection is presented. Various fluorescence microscopy techniques are presented with a focus on how the light is delivered to the sample (i.e., light density) and pros and cons for use with living specimens. The reader is also directed to other publications that go into these topics in more detail. Methods are described on how to prepare samples for single cell migration assays, how to measure cell migration rates (e.g., bright-field, semi-automated, and automated), and how to measure focal adhesion turnover rates. Details of how to correct images for background intensity and field-illumination uniformity artifacts for quantitative imaging are also described. Overall, this chapter will be helpful to scientists who are interested in imaging live specimens using fluorescence microscopy techniques. It will be of particular interest to anyone wanting to perform quantitative fluorescence imaging, and wanting to measure cell migration rates, and focal adhesion dynamics.

  12. ZDHHC3 Tyrosine Phosphorylation Regulates Neural Cell Adhesion Molecule Palmitoylation

    PubMed Central

    Lievens, Patricia Marie-Jeanne; Kuznetsova, Tatiana; Kochlamazashvili, Gaga; Cesca, Fabrizia; Gorinski, Natalya; Galil, Dalia Abdel; Cherkas, Volodimir; Ronkina, Natalia; Lafera, Juri; Gaestel, Matthias

    2016-01-01

    The neural cell adhesion molecule (NCAM) mediates cell-cell and cell-matrix adhesion. It is broadly expressed in the nervous system and regulates neurite outgrowth, synaptogenesis, and synaptic plasticity. Previous in vitro studies revealed that palmitoylation of NCAM is required for fibroblast growth factor 2 (FGF2)-stimulated neurite outgrowth and identified the zinc finger DHHC (Asp-His-His-Cys)-containing proteins ZDHHC3 and ZDHHC7 as specific NCAM-palmitoylating enzymes. Here, we verified that FGF2 controlled NCAM palmitoylation in vivo and investigated molecular mechanisms regulating NCAM palmitoylation by ZDHHC3. Experiments with overexpression and pharmacological inhibition of FGF receptor (FGFR) and Src revealed that these kinases control tyrosine phosphorylation of ZDHHC3 and that ZDHHC3 is phosphorylated by endogenously expressed FGFR and Src proteins. By site-directed mutagenesis, we found that Tyr18 is an FGFR1-specific ZDHHC3 phosphorylation site, while Tyr295 and Tyr297 are specifically phosphorylated by Src kinase in cell-based and cell-free assays. Abrogation of tyrosine phosphorylation increased ZDHHC3 autopalmitoylation, enhanced interaction with NCAM, and upregulated NCAM palmitoylation. Expression of ZDHHC3 with tyrosine mutated in cultured hippocampal neurons promoted neurite outgrowth. Our findings for the first time highlight that FGFR- and Src-mediated tyrosine phosphorylation of ZDHHC3 modulates ZDHHC3 enzymatic activity and plays a role in neuronal morphogenesis. PMID:27247265

  13. Different Organization of Type I Collagen Immobilized on Silanized and Nonsilanized Titanium Surfaces Affects Fibroblast Adhesion and Fibronectin Secretion.

    PubMed

    Marín-Pareja, Nathalia; Cantini, Marco; González-García, Cristina; Salvagni, Emiliano; Salmerón-Sánchez, Manuel; Ginebra, Maria-Pau

    2015-09-23

    Silanization has emerged in recent years as a way to obtain a stronger and more stable attachment of biomolecules to metallic substrates. However, its impact on protein conformation, a key aspect that influences cell response, has hardly been studied. In this work, we analyzed by atomic force microscopy (AFM) the distribution and conformation of type I collagen on plasma-treated surfaces before and after silanization. Subsequently, we investigated the effect of the different collagen conformations on fibroblasts adhesion and fibronectin secretion by immunofluorescence analyses. Two different organosilanes were used on plasma-treated titanium surfaces, either 3-chloropropyl-triethoxy-silane (CPTES) or 3-glycidyloxypropyl-triethoxy-silane (GPTES). The properties and amount of the adsorbed collagen were assessed by contact angle, X-ray photoelectron spectroscopy, optical waveguide lightmode spectroscopy, and AFM. AFM studies revealed different conformations of type I collagen depending on the silane employed. Collagen was organized in fibrillar networks over very hydrophilic (plasma treated titanium) or hydrophobic (silanized with CPTES) surfaces, the latter forming little globules with a beads-on-a-string appearance, whereas over surfaces presenting an intermediate hydrophobic character (silanized with GPTES), collagen was organized into clusters with a size increasing at higher protein concentration in solution. Cell response was strongly affected by collagen conformation, especially at low collagen density. The samples exhibiting collagen organized in globular clusters (GPTES-functionalized samples) favored a faster and better fibroblast adhesion as well as better cell spreading, focal adhesions formation, and more pronounced fibronectin fibrillogenesis. In contrast, when a certain protein concentration was reached at the material surface, the effect of collagen conformation was masked, and similar fibroblast response was observed in all samples.

  14. A standardized bamboo leaf extract inhibits monocyte adhesion to endothelial cells by modulating vascular cell adhesion protein-1

    PubMed Central

    Choi, Sunga; Park, Myoung Soo; Lee, Yu Ran; Lee, Young Chul; Kim, Tae Woo; Do, Seon-Gil; Kim, Dong Seon

    2013-01-01

    Bamboo leaves (Phyllostachys pubescens Mazel ex J. Houz (Poacea)) have a long history of food and medical applications in Asia, including Japan and Korea. They have been used as a traditional medicine for centuries. We investigated the mechanism of anti-inflammatory activity of a bamboo leaf extract (BLE) on tumor necrosis factor-alpha (TNF-α)-induced monocyte adhesion in human umbilical vein endothelial cells (HUVECs). Exposure of HUVECs to BLE did not inhibit cell viability or cause morphological changes at concentrations ranging from 1 µg/ml to 1 mg/ml. Treatment with 0.1 mg/ml BLE caused 63% inhibition of monocyte adhesion in TNF-α-activated HUVECs, which was associated with 38.4% suppression of vascular cell adhesion molecule-1 expression. Furthermore, TNF-α-induced reactive oxygen species generation was decreased to 47.9% in BLE treated TNF-α-activated HUVECs. BLE (0.05 mg/ml) also caused about 50% inhibition of interleukin-6 secretion from lipopolysaccharide-stimulated monocyte. The results indicate that BLE may be clinically useful as an anti-inflammatory or anti-oxidant for human cardiovascular disease including atherosclerosis. PMID:23422838

  15. BMP4-induced differentiation of a rat spermatogonial stem cell line causes changes in its cell adhesion properties.

    PubMed

    Carlomagno, Gianfranco; van Bragt, Maaike P A; Korver, Cindy M; Repping, Sjoerd; de Rooij, Dirk G; van Pelt, Ans M M

    2010-11-01

    Spermatogonial stem cells (SSCs) are at the basis of the spermatogenic process and are essential for the continuous lifelong production of spermatozoa. Although several factors that govern SSC self-renewal and differentiation have been investigated, the direct effect of such factors on SSCs has not yet been studied, mainly because of the absence of markers to identify SSCs and the lack of effective methods to obtain and culture a pure population of SSCs. We now have used a previously established rat SSC cell line (GC-6spg) to elucidate the role of BMP4 in SSC differentiation. We found that GC-6spg cells cultured in the presence of BMP4 upregulate KIT expression, which is an early marker for differentiating spermatogonia. GC-6spg cells were found to express three BMP4 receptors and the downstream SMAD1/5/8 proteins were phosphorylated during BMP4-induced differentiation. A time-course DNA micro-array analysis revealed a total of 529 differentially regulated transcripts (≥2-fold), including several known downstream targets of BMP4 such as Id2 and Gata2. Pathway analysis revealed that the most affected pathways were those involved in adherens junctions, focal junctions, gap junctions, cell adhesion molecules, and regulation of actin cytoskeleton. Interestingly, among the genes belonging to the most strongly affected adhesion pathways was Cdh1 (known as E-cadherin), an adhesion molecule known to be expressed by a subpopulation of spermatogonia including SSCs. Overall, our results suggest that BMP4 induces early differentiation of SSCs in a direct manner by affecting cell adhesion pathways.

  16. Thermodynamics of cell adhesion. II. Freely mobile repellers.

    PubMed Central

    Torney, D C; Dembo, M; Bell, G I

    1986-01-01

    The equilibrium adhesion of a cell or vesicle to a substrate is analyzed in a theoretical model in which two types of mobile molecules in the cell membrane are of interest: receptors that can form bonds with fixed ligands in the substrate and repellers that repel the substrate. If the repulsion between the repeller molecule and substrate is greater than kT, there is substantial redistribution of the repellers from the contact area. Coexisting equilibrium states are observed having comparable free energies (a) with unstretched bonds and repeller redistribution and (b) with stretched bonds and partial redistribution. PMID:3955182

  17. Electrochemically controlled stiffness of multilayers for manipulation of cell adhesion.

    PubMed

    Sun, Yi-xin; Ren, Ke-feng; Wang, Jin-lei; Chang, Guo-xun; Ji, Jian

    2013-06-12

    Stimuli-responsive thin films attract considerable attention in different fields. Herein, an electrochemical redox multilayers with tunable stiffness is constructed through the layer-by-layer self-assembly method. The redox ferrocene modified poly(ethylenimine) play an essential role to induce multilayers' swelling/shrinking under an electrochemical stimulus, resulting reversible change of elastic modulus of the multilayers. The adhesion of fibroblast cells can be thus controlled from well spreading to round shape. Such soft multilayers with electrochemically controlled stiffness could have potentials for cell-based applications.

  18. PrP-dependent cell adhesion in N2a neuroblastoma cells.

    PubMed

    Mangé, Alain; Milhavet, Ollivier; Umlauf, David; Harris, David; Lehmann, Sylvain

    2002-03-13

    The cellular isoform of prion protein (PrP(C)) is a ubiquitous glycoprotein expressed by most tissues and with a biological function yet to be determined. Here, we have used a neuroblastoma cell model to investigate the involvement of PrP in cell adhesion. Incubation of single cell suspension induced cell-cell adhesion and formation of cell aggregates. Interestingly, cells overexpressing PrP exhibit increased cation-independent aggregation. Aggregation was reduced after phosphatidylinositol-specific phospholipase C release of the protein and by pre-incubation of cells with an antibody raised against the N-terminal part of PrP(C). Our paradigm allows the study of the function of PrP as an intercellular adhesion molecule and a cell surface ligand or receptor.

  19. The interplay of cell–cell and cell–substrate adhesion in collective cell migration

    PubMed Central

    Wang, Chenlu; Chowdhury, Sagar; Driscoll, Meghan; Parent, Carole A.; Gupta, S. K.; Losert, Wolfgang

    2014-01-01

    Collective cell migration often involves notable cell–cell and cell–substrate adhesions and highly coordinated motion of touching cells. We focus on the interplay between cell–substrate adhesion and cell–cell adhesion. We show that the loss of cell-surface contact does not significantly alter the dynamic pattern of protrusions and retractions of fast migrating amoeboid cells (Dictyostelium discoideum), but significantly changes their ability to adhere to other cells. Analysis of the dynamics of cell shapes reveals that cells that are adherent to a surface may coordinate their motion with neighbouring cells through protrusion waves that travel across cell–cell contacts. However, while shape waves exist if cells are detached from surfaces, they do not couple cell to cell. In addition, our investigation of actin polymerization indicates that loss of cell-surface adhesion changes actin polymerization at cell–cell contacts. To further investigate cell–cell/cell–substrate interactions, we used optical micromanipulation to form cell–substrate contact at controlled locations. We find that both cell-shape dynamics and cytoskeletal activity respond rapidly to the formation of cell–substrate contact. PMID:25165597

  20. Regulation of epithelial cell organization by tuning cell-substrate adhesion.

    PubMed

    Ravasio, Andrea; Le, Anh Phuong; Saw, Thuan Beng; Tarle, Victoria; Ong, Hui Ting; Bertocchi, Cristina; Mège, René-Marc; Lim, Chwee Teck; Gov, Nir S; Ladoux, Benoit

    2015-10-01

    Collective migration of cells is of fundamental importance for a number of biological functions such as tissue development and regeneration, wound healing and cancer metastasis. The movement of cell groups consisting of multiple cells connected by cell-cell junctions depends on both extracellular and intercellular contacts. Epithelial cell assemblies are thus regulated by a cross-talk between cell-substrate and cell-cell interactions. Here, we investigated the onset of collective migration in groups of cells as they expand from a few cells into large colonies as a function of extracellular matrix (ECM) protein coating. By varying the amount of ECM presented to the cells, we observe that the mode of colony expansion, as well as their overall geometry, is strongly dependent on substrate adhesiveness. On high ECM protein coated surfaces, cells at the edges of the colonies are well spread exhibiting large outward-pointing protrusive activity, whereas cellular colonies display more circular and convex shapes on less adhesive surfaces. Actin structures at the edge of the colonies also show different organizations with the formation of lamellipodial structures on highly adhesive surfaces and a pluricellular actin cable on less adhesive ones. The analysis of traction forces and cell velocities within the cellular assemblies confirm these results. By increasing ECM protein density, cells exert higher traction forces together with a higher outward motility at the edges. Furthermore, tuning cell-cell adhesion of epithelial cells modified the mode of expansion of the colonies. Finally, we used a recently developed computational model to recapitulate the emergent experimental behaviors of expanding cell colonies and extract that the main effect of the different cell-substrate interactions is on the ability of edge cells to form outward lamellipodia-driven motility. Overall, our data suggest that switching behaviors of epithelial cell assemblies result in a tug-of-war between

  1. Quantifying the effect of electric current on cell adhesion studied by single-cell force spectroscopy.

    PubMed

    Jaatinen, Leena; Young, Eleanore; Hyttinen, Jari; Vörös, János; Zambelli, Tomaso; Demkó, László

    2016-03-20

    This study presents the effect of external electric current on the cell adhesive and mechanical properties of the C2C12 mouse myoblast cell line. Changes in cell morphology, viability, cytoskeleton, and focal adhesion structure were studied by standard staining protocols, while single-cell force spectroscopy based on the fluidic force microscopy technology provided a rapid, serial quantification and detailed analysis of cell adhesion and its dynamics. The setup allowed measurements of adhesion forces up to the μN range, and total detachment distances over 40 μm. Force-distance curves have been fitted with a simple elastic model including a cell detachment protocol in order to estimate the Young's modulus of the cells, as well as to reveal changes in the dynamic properties as functions of the applied current dose. While the cell spreading area decreased monotonously with increasing current doses, small current doses resulted only in differences related to cell elasticity. Current doses above 11 As/m(2), however, initiated more drastic changes in cell morphology, viability, cellular structure, as well as in properties related to cell adhesion. The observed differences, eventually leading to cell death toward higher doses, might originate from both the decrease in pH and the generation of reactive oxygen species.

  2. Study of cell-matrix adhesion dynamics using surface plasmon resonance imaging ellipsometry.

    PubMed

    Kim, Se-Hwa; Chegal, Won; Doh, Junsang; Cho, Hyun Mo; Moon, Dae Won

    2011-04-06

    The interaction of cells with extracellular matrix, termed cell-matrix adhesions, importantly governs multiple cellular phenomena. Knowledge of the functional dynamics of cell-matrix adhesion could provide critical clues for understanding biological phenomena. We developed surface plasmon resonance imaging ellipsometry (SPRIE) to provide high contrast images of the cell-matrix interface in unlabeled living cells. To improve the contrast and sensitivity, the null-type imaging ellipsometry technique was integrated with an attenuated total reflection coupler. We verified that the imaged area of SPRIE was indeed a cell-matrix adhesion area by confocal microscopy imaging. Using SPRIE, we demonstrated that three different cell types exhibit distinct features of adhesion. SPRIE was applied to diverse biological systems, including during cell division, cell migration, and cell-cell communication. We imaged the cell-matrix anchorage of mitotic cells, providing the first label-free imaging of this interaction to our knowledge. We found that cell-cell communication can alter cell-matrix adhesion, possibly providing direct experimental evidence for cell-cell communication-mediated changes in cell adhesion. We also investigated shear-stress-induced adhesion dynamics in real time. Based on these data, we expect that SPRIE will be a useful methodology for studying the role of cell-matrix adhesion in important biological phenomena.

  3. Measurement of cell adhesion force by vertical forcible detachment using an arrowhead nanoneedle and atomic force microscopy

    SciTech Connect

    Ryu, Seunghwan; Hashizume, Yui; Mishima, Mari; Kawamura, Ryuzo; Tamura, Masato; Matsui, Hirofumi; Matsusaki, Michiya; Akashi, Mitsuru; Nakamura, Chikashi

    2014-08-15

    Graphical abstract: - Highlights: • We developed a method to measure cell adhesion force by detaching cell using an arrowhead nanoneedle and AFM. • A nanofilm consisting of fibronectin and gelatin was formed on cell surface to reinforce the cell cortex. • By the nanofilm lamination, detachment efficiencies of strongly adherent cell lines were improved markedly. - Abstract: The properties of substrates and extracellular matrices (ECM) are important factors governing the functions and fates of mammalian adherent cells. For example, substrate stiffness often affects cell differentiation. At focal adhesions, clustered–integrin bindings link cells mechanically to the ECM. In order to quantitate the affinity between cell and substrate, the cell adhesion force must be measured for single cells. In this study, forcible detachment of a single cell in the vertical direction using AFM was carried out, allowing breakage of the integrin–substrate bindings. An AFM tip was fabricated into an arrowhead shape to detach the cell from the substrate. Peak force observed in the recorded force curve during probe retraction was defined as the adhesion force, and was analyzed for various types of cells. Some of the cell types adhered so strongly that they could not be picked up because of plasma membrane breakage by the arrowhead probe. To address this problem, a technique to reinforce the cellular membrane with layer-by-layer nanofilms composed of fibronectin and gelatin helped to improve insertion efficiency and to prevent cell membrane rupture during the detachment process, allowing successful detachment of the cells. This method for detaching cells, involving cellular membrane reinforcement, may be beneficial for evaluating true cell adhesion forces in various cell types.

  4. Light-triggered in vivo Activation of Adhesive Peptides Regulates Cell Adhesion, Inflammation and Vascularization of Biomaterials

    PubMed Central

    Lee, Ted T.; García, José R.; Paez, Julieta; Singh, Ankur; Phelps, Edward A.; Weis, Simone; Shafiq, Zahid; Shekaran, Asha; del Campo, Aránzazu; García, Andrés J.

    2014-01-01

    Materials engineered to elicit targeted cellular responses in regenerative medicine must display bioligands with precise spatial and temporal control. Although materials with temporally regulated presentation of bioadhesive ligands using external triggers, such as light and electric fields, have been recently realized for cells in culture, the impact of in vivo temporal ligand presentation on cell-material responses is unknown. Here, we present a general strategy to temporally and spatially control the in vivo presentation of bioligands using cell adhesive peptides with a protecting group that can be easily removed via transdermal light exposure to render the peptide fully active. We demonstrate that non-invasive, transdermal time-regulated activation of cell-adhesive RGD peptide on implanted biomaterials regulates in vivo cell adhesion, inflammation, fibrous encapsulation, and vascularization of the material. This work shows that triggered in vivo presentation of bioligands can be harnessed to direct tissue reparative responses associated with implanted biomaterials. PMID:25502097

  5. Light-triggered in vivo activation of adhesive peptides regulates cell adhesion, inflammation and vascularization of biomaterials

    NASA Astrophysics Data System (ADS)

    Lee, Ted T.; García, José R.; Paez, Julieta I.; Singh, Ankur; Phelps, Edward A.; Weis, Simone; Shafiq, Zahid; Shekaran, Asha; Del Campo, Aránzazu; García, Andrés J.

    2015-03-01

    Materials engineered to elicit targeted cellular responses in regenerative medicine must display bioligands with precise spatial and temporal control. Although materials with temporally regulated presentation of bioadhesive ligands using external triggers, such as light and electric fields, have recently been realized for cells in culture, the impact of in vivo temporal ligand presentation on cell-material responses is unknown. Here, we present a general strategy to temporally and spatially control the in vivo presentation of bioligands using cell-adhesive peptides with a protecting group that can be easily removed via transdermal light exposure to render the peptide fully active. We demonstrate that non-invasive, transdermal time-regulated activation of cell-adhesive RGD peptide on implanted biomaterials regulates in vivo cell adhesion, inflammation, fibrous encapsulation, and vascularization of the material. This work shows that triggered in vivo presentation of bioligands can be harnessed to direct tissue reparative responses associated with implanted biomaterials.

  6. Liprin-α1 and ERC1 control cell edge dynamics by promoting focal adhesion turnover

    PubMed Central

    Astro, Veronica; Tonoli, Diletta; Chiaretti, Sara; Badanai, Sabrina; Sala, Kristyna; Zerial, Marino; de Curtis, Ivan

    2016-01-01

    Liprin-α1 and ERC1 are interacting scaffold proteins regulating the motility of normal and tumor cells. They act as part of plasma membrane-associated platforms at the edge of motile cells to promote protrusion by largely unknown mechanisms. Here we identify an amino-terminal region of the liprin-α1 protein (liprin-N) that is sufficient and necessary for the interaction with other liprin-α1 molecules. Similar to liprin-α1 or ERC1 silencing, expression of the liprin-N negatively affects tumor cell motility and extracellular matrix invasion, acting as a dominant negative by interacting with endogenous liprin-α1 and causing the displacement of the endogenous ERC1 protein from the cell edge. Interfering with the localization of ERC1 at the cell edge inhibits the disassembly of focal adhesions, impairing protrusion. Liprin-α1 and ERC1 proteins colocalize with active integrin β1 clusters distinct from those colocalizing with cytoplasmic focal adhesion proteins, and influence the localization of peripheral Rab7-positive endosomes. We propose that liprin-α1 and ERC1 promote protrusion by displacing cytoplasmic adhesion components to favour active integrin internalization into Rab7-positive endosomes. PMID:27659488

  7. Liprin-α1 and ERC1 control cell edge dynamics by promoting focal adhesion turnover.

    PubMed

    Astro, Veronica; Tonoli, Diletta; Chiaretti, Sara; Badanai, Sabrina; Sala, Kristyna; Zerial, Marino; de Curtis, Ivan

    2016-09-23

    Liprin-α1 and ERC1 are interacting scaffold proteins regulating the motility of normal and tumor cells. They act as part of plasma membrane-associated platforms at the edge of motile cells to promote protrusion by largely unknown mechanisms. Here we identify an amino-terminal region of the liprin-α1 protein (liprin-N) that is sufficient and necessary for the interaction with other liprin-α1 molecules. Similar to liprin-α1 or ERC1 silencing, expression of the liprin-N negatively affects tumor cell motility and extracellular matrix invasion, acting as a dominant negative by interacting with endogenous liprin-α1 and causing the displacement of the endogenous ERC1 protein from the cell edge. Interfering with the localization of ERC1 at the cell edge inhibits the disassembly of focal adhesions, impairing protrusion. Liprin-α1 and ERC1 proteins colocalize with active integrin β1 clusters distinct from those colocalizing with cytoplasmic focal adhesion proteins, and influence the localization of peripheral Rab7-positive endosomes. We propose that liprin-α1 and ERC1 promote protrusion by displacing cytoplasmic adhesion components to favour active integrin internalization into Rab7-positive endosomes.

  8. Significant role of adhesion properties of primary osteoblast-like cells in early adhesion events for chondroitin sulfate and dermatan sulfate surface molecules.

    PubMed

    Stanford, C M; Solursh, M; Keller, J C

    1999-12-05

    The purpose of this study was to characterize the role of cell surface adhesive macromolecules through enzyme modulation and metabolic recovery prior to and during a kinetic cell adhesion assay. Primary rat calvarial osteoblast-like cells were derived from Sprague-Dawley calvarial plates. Cell adhesion kinetics was evaluated with the definition of first-order adhesion kinetics. Osteoblasts were incubated in an adhesion buffer for 1 h prior to a cell attachment assay using various enzymes to remove cell surface glycosaminoglycans (GAGs). A subtractive adhesion analysis was performed by plating cells at 5 x 10(4)/well for variable periods through 2 h. The medium was collected, the well surface washed and pooled, and the number of cells enumerated with a Coulter Counter. Cell adhesion demonstrated first-order logarithmic adhesion kinetics in the first 60 min. Scatchard analysis demonstrated a linear relationship. Preexposure of cells to various enzyme combinations demonstrated that 50% of the equilibrium adhesion was dependent on chondroitin sulfate or dermatan sulfate surface macromolecules. These results were confirmed with pretreatment with a metabolic inhibitor of GAG synthesis (beta-D-xyloside). These results suggest an important role for cell associated chondroitin sulfate and dermatan sulfate in cell adhesion in addition to Arg-Gly-Asp or integrin mediated adhesion events.

  9. Disruption of cell adhesion by an antibody targeting the cell-adhesive intermediate (X-dimer) of human P-cadherin

    PubMed Central

    Kudo, Shota; Caaveiro, Jose M. M.; Nagatoishi, Satoru; Miyafusa, Takamitsu; Matsuura, Tadashi; Sudou, Yukio; Tsumoto, Kouhei

    2017-01-01

    Human P-cadherin is a cell adhesion protein of the family of classical cadherins, the overexpression of which is correlated with poor prognosis in various types of cancer. Antibodies inhibiting cell-cell adhesion mediated by P-cadherin show clear therapeutic effect, although the mechanistic basis explaining their effectiveness is still unclear. Based on structural, physicochemical, and functional analyses, we have elucidated the molecular mechanism of disruption of cell adhesion by antibodies targeting human P-cadherin. Herein we have studied three different antibodies, TSP5, TSP7, and TSP11, each recognizing a different epitope on the surface of the cell-adhesive domain (EC1). Although all these three antibodies recognized human P-cadherin with high affinity, only TSP7 disrupted cell adhesion. Notably, we demonstrated that TSP7 abolishes cell adhesion by disabling the so-called X-dimer (a kinetic adhesive intermediate), in addition to disrupting the strand-swap dimer (the final thermodynamic state). The inhibition of the X-dimer was crucial for the overall inhibitory effect, raising the therapeutic value of a kinetic intermediary not only for preventing, but also for reversing, cell adhesion mediated by a member of the classical cadherin family. These findings should help to design more innovative and effective therapeutic solutions targeting human P-cadherin. PMID:28045038

  10. Dendritic cell activation is influenced by cyclic mechanical strain when cultured on adhesive substrates

    PubMed Central

    Lewis, Jamal S.; Dolgova, Natalia; Chancellor, T.J.; Acharya, Abhinav P.; Karpiak, Jerome V.; Lele, Tanmay P.; Keselowsky, Benjamin G.

    2014-01-01

    Dendritic cells (DCs), key regulators of tolerance and immunity, have been found to reside in mechanically active tissues such as the interior layers of the arterial wall, which experience cyclic radial wall strain due to pulsatile blood flow. Although experimentally difficult to determine in vivo, it is reasonable to postulate DCs experience the mechanical forces in such mechanically active tissues. However, it is currently unknown how DCs respond to cyclic mechanical strain. In order to explore the hypothesis that DCs are responsive to mechanical strain, DCs were cultured in vitro on pre-adsorbed adhesive proteins (e.g., laminin, collagen, fibrinogen) and 1 Hz cyclic strain was applied for various durations and strain magnitudes. It was determined that a strain magnitude of 10% and 24 h duration adversely affected DC viability compared to no-strain controls, but culture on certain adhesive substrates provided modest protection of viability under this harsh strain regime. In contrast, application of 1 h of 1 Hz cyclic 3% strain did not affect DC viability and this strain regime was used for the remaining experiments for quantifying DC activation and T-cell priming capability. Application of 3% strain increased expression of stimulatory (MHC-II) and co-stimulatory molecules (CD86, CD40), and this effect was generally increased by culture on pre-coated adhesive substrates. Interestingly, the cytokine secretion profile of DCs was not significantly affected by strain. Lastly, strained DCs demonstrated increased stimulation of allogeneic T cell proliferation, in a manner that was independent of the adhesive substrate. These observations indicate generation of a DC consistent with what has been described as a semi-mature phenotype. This work begins elucidating a potential role for DCs in tissue environments exposed to cyclic mechanical forces. PMID:24008042

  11. Regulation of epithelial cell organization by tuning cell-substrate adhesion

    PubMed Central

    Ravasio, Andrea; Le, Anh Phuong; Saw, Thuan Beng; Tarle, Victoria; Ong, Hui Ting; Bertocchi, Cristina; Mège, René-Marc; Lim, Chwee Teck; Gov, Nir; Ladoux, Benoit

    2017-01-01

    Collective migration of cells is of fundamental importance for a number of biological functions such as tissue development and regeneration, wound healing and cancer metastasis. The movement of cell groups consisting of multiple cells connected by cell-cell junctions depends on both extracellular and intercellular contacts. Epithelial cell assemblies are thus regulated by a cross-talk between cell-substrate and cell-cell interactions. Here, we investigated the onset of collective migration in groups of cells as they expand from few cells into large colonies as a function of extra-cellular matrix (ECM) protein coating. By varying the amount of extracellular matrix proteins (ECM) presented to the cells, we observe that the mode of colony expansion as well as their overall geometry is strongly dependent on substrate adhesiveness. On high ECM protein coated surfaces, cells at the edges of the colonies are well spread exhibiting large outward-pointing protrusive activity whereas cellular colonies display more circular and convex shapes on less adhesive surfaces. Actin structures at the edge of the colonies also show different organizations with the formation of lamellipodial structures on highly adhesive surfaces and a pluricellular actin cable on less adhesive ones. The analysis of traction forces and cell velocities within the cellular assemblies confirm these results. By increasing ECM protein density, cells exert higher traction forces together with a higher outward motility at the edges. Furthermore, tuning cell-cell adhesion of epithelial cell lines modified the mode of expansion of the colonies. Finally, we used a recently developed computational model to recapitulate the emergent experimental behaviors of expanding cell colonies and extract that the main observed differences are dependent on the different cell-substrate interactions. Overall, our data suggest that switching behaviors of epithelial cell assemblies results of a tug-of-war between friction forces

  12. Urokinase plasminogen activator receptor: a functional integrator of extracellular proteolysis, cell adhesion, and signal transduction.

    PubMed

    Ferraris, Gian Maria Sarra; Sidenius, Nicolai

    2013-06-01

    The urokinase plasminogen activator receptor (uPAR) is a cell surface receptor involved in a multitude of physiologic and pathologic processes. uPAR regulates simultaneously a branch of the plasminogen activator system and modulates cell adhesion and intracellular signaling by interacting with extracellular matrix components and signaling receptors. The multiple uPAR functions are deeply interconnected, and their integration determines the effects that uPAR expression triggers in different contexts. The proteolytic function of uPAR affects both the signaling and the adhesive functions of the receptor, whereas these latter two are closely interconnected. This review focuses on the molecular mechanisms that connect and mutually regulate the different uPAR functions. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  13. 3D Surface Topology Guides Stem Cell Adhesion and Differentiation

    PubMed Central

    Viswanathan, Priyalakshmi; Ondeck, Matthew G.; Chirasatitsin, Somyot; Nghamkham, Kamolchanok; Reilly, Gwendolen C.; Engler, Adam J.; Battaglia, Giuseppe

    2015-01-01

    Polymerized high internal phase emulsion (polyHIPE) foams are extremely versatile materials for investigating cell-substrate interactions in vitro. Foam morphologies can be controlled by polymerization conditions to result in either open or closed pore structures with different levels of connectivity, consequently enabling the comparison between 2D and 3D matrices using the same substrate with identical surface chemistry conditions. Additionally, here we achieve the control of pore surface topology (i.e. how different ligands are clustered together) using amphiphilic block copolymers as emulsion stabilisers. We demonstrate that adhesion of human mesenchymal progenitor (hES-MP) cells cultured on polyHIPE foams is dependent on foam surface topology and chemistry but is independent of porosity and interconnectivity. We also demonstrate that the interconnectivity, architecture and surface topology of the foams has an effect on the osteogenic differentiation potential of hES-MP cells. Together these data demonstrate that the adhesive heterogeneity of a 3D scaffold could regulate not only mesenchymal stem cell attachment but also cell behavior in the absence of soluble growth factors. PMID:25818420

  14. A discrete approach for modeling cell-matrix adhesions

    NASA Astrophysics Data System (ADS)

    Escribano, J.; Sánchez, M. T.; García-Aznar, J. M.

    2014-06-01

    During recent years the interaction between the extracellular matrix and the cytoskeleton of the cell has been object of numerous studies due to its importance in cell migration processes. These interactions are performed through protein clutches, known as focal adhesions. For migratory cells these focal adhesions along with force generating processes in the cytoskeleton are responsible for the formation of protrusion structures like lamellipodia or filopodia. Much is known about these structures: the different proteins that conform them, the players involved in their formation or their role in cell migration. Concretely, growth-cone filopodia structures have attracted significant attention because of their role as cell sensors of their surrounding environment and its complex behavior. On this matter, a vast myriad of mathematical models has been presented to explain its mechanical behavior. In this work, we aim to study the mechanical behavior of these structures through a discrete approach. This numerical model provides an individual analysis of the proteins involved including spatial distribution, interaction between them, and study of different phenomena, such as clutches unbinding or protein unfolding.

  15. The effect of an external magnetic force on cell adhesion and proliferation of magnetically labeled mesenchymal stem cells

    PubMed Central

    2010-01-01

    Background As the strategy for tissue regeneration using mesenchymal stem cells (MSCs) for transplantation, it is necessary that MSCs be accumulated and kept in the target area. To accumulate MSCs effectively, we developed a novel technique for a magnetic targeting system with magnetically labeled MSCs and an external magnetic force. In this study, we examined the effect of an external magnetic force on magnetically labeled MSCs in terms of cell adhesion and proliferation. Methods Magnetically labeled MSCs were plated at the bottom of an insert under the influence of an external magnetic force for 1 hour. Then the inserts were turned upside down for between 1 and 24 hours, and the number of MSCs which had fallen from the membrane was counted. The gene expression of MSCs affected magnetic force was analyzed with microarray. In the control group, the same procedure was done without the external magnetic force. Results At 1 hour after the inserts were turned upside down, the average number of fallen MSCs in the magnetic group was significantly smaller than that in the control group, indicating enhanced cell adhesion. At 24 hours, the average number of fallen MSCs in the magnetic group was also significantly smaller than that in control group. In the magnetic group, integrin alpha2, alpha6, beta3 BP, intercellular adhesion molecule-2 (ICAM-2), platelet/endothelial cell adhesion molecule-1 (PECAM-1) were upregulated. At 1, 2 and 3 weeks after incubation, there was no statistical significant difference in the numbers of MSCs in the magnetic group and control group. Conclusions The results indicate that an external magnetic force for 1 hour enhances cell adhesion of MSCs. Moreover, there is no difference in cell proliferation after using an external magnetic force on magnetically labeled MSCs. PMID:20152029

  16. Conformational Dynamics of the Focal Adhesion Targeting Domain Control Specific Functions of Focal Adhesion Kinase in Cells*

    PubMed Central

    Kadaré, Gress; Gervasi, Nicolas; Brami-Cherrier, Karen; Blockus, Heike; El Messari, Said; Arold, Stefan T.; Girault, Jean-Antoine

    2015-01-01

    Focal adhesion (FA) kinase (FAK) regulates cell survival and motility by transducing signals from membrane receptors. The C-terminal FA targeting (FAT) domain of FAK fulfils multiple functions, including recruitment to FAs through paxillin binding. Phosphorylation of FAT on Tyr925 facilitates FA disassembly and connects to the MAPK pathway through Grb2 association, but requires dissociation of the first helix (H1) of the four-helix bundle of FAT. We investigated the importance of H1 opening in cells by comparing the properties of FAK molecules containing wild-type or mutated FAT with impaired or facilitated H1 openings. These mutations did not alter the activation of FAK, but selectively affected its cellular functions, including self-association, Tyr925 phosphorylation, paxillin binding, and FA targeting and turnover. Phosphorylation of Tyr861, located between the kinase and FAT domains, was also enhanced by the mutation that opened the FAT bundle. Similarly phosphorylation of Ser910 by ERK in response to bombesin was increased by FAT opening. Although FAK molecules with the mutation favoring FAT opening were poorly recruited at FAs, they efficiently restored FA turnover and cell shape in FAK-deficient cells. In contrast, the mutation preventing H1 opening markedly impaired FAK function. Our data support the biological importance of conformational dynamics of the FAT domain and its functional interactions with other parts of the molecule. PMID:25391654

  17. Low Doses of Curcuma longa Modulates Cell Migration and Cell-Cell Adhesion.

    PubMed

    de Campos, Paloma Santos; Matte, Bibiana Franzen; Diel, Leonardo Francisco; Jesus, Luciano Henrique; Bernardi, Lisiane; Alves, Alessandro Menna; Rados, Pantelis Varvaki; Lamers, Marcelo Lazzaron

    2017-09-01

    Cell invasion and metastasis are involved in clinical failures in cancer treatment, and both events require the acquisition of a migratory behavior by tumor cells. Curcumin is a promising natural product with anti-proliferative activity, but its effects on cell migration are still unclear. We evaluated the effects of curcumin on the proliferation, apoptosis, migration, and cell-cell adhesion of keratinocyte, oral squamous cell carcinoma (OSCC), and fibroblast cell lines, as well as in a xenograft model of OSCC. Curcumin (2 μM) decreased cell proliferation in cell lines with mesenchymal characteristics, while cell death was detected only at 50 μM. We observed that highly migratory cells showed a decrease on migration speed and directionality when treated with 2 or 5 μM of curcumin (50% and 40%, respectively, p < 0.05). Using spheroids, we observed that curcumin dose dependently decreased cell-cell adhesion, especially on tumor-derived spheroids. Also, in a xenograft model with patient-derived OSCC cells, the administration of curcumin decreased tumor growth and aggressiveness when compared with untreated tumors, indicating the potential antitumor effect in oral cancer. These results suggest that lower doses of curcumin can influence several steps involved in tumorigenesis, including migration properties, suggesting a possible use in cancer therapy. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  18. Can common adhesion molecules and microtopography affect cellular elasticity? A combined atomic force microscopy and optical study.

    PubMed

    McPhee, Gordon; Dalby, Matthew J; Riehle, Mathis; Yin, Huabing

    2010-10-01

    The phenomenon that cells respond to chemical and topographic cues in their surroundings has been widely examined and exploited in many fields ranging from basic life science research to biomedical therapeutics. Adhesion promoting molecules such as poly-L-lysine (PLL) and fibronectin (Fn) are commonly used for in vitro cell assays to promote cell spreading/proliferation on tissue culture plastic and to enhance the biocompatibility of biomedical devices. Likewise, engineered topography is often used to guide cell growth and differentiation. Little is known about how these cues affect the biomechanical properties of cells and subsequent cell function. In this study we have applied atomic force microscopy (AFM) to investigate these biomechanical properties. In the first stage of the study we formulated a rigorous approach to quantify cellular elasticity using AFM. Operational factors, including indentation depth and speed, and mathematical models for data fitting have been systematically evaluated. We then quantified how PLL, Fn and microtopography affected cellular elasticity and the organization of the cytoskeleton. Cellular elasticity after 1 day in culture was greater on a Fn-coated surface as compared to PLL or glass. These statistically significant differences disappeared after two more days in culture. In contrast, the significantly higher elasticity associated with cells grown on micrometric grooves remained for at least 3 days. This work sheds light on the apparently simple but debatable questions: "Are engineered chemical cues eventually masked by a cell's own matrix proteins and so only exert short-term influence? Does engineered topography as well as engineered chemistry affect cell elasticity?"

  19. Cellular Adhesion Promotes Prostate Cancer Cells Escape from Dormancy

    PubMed Central

    Ruppender, Nazanin; Larson, Sandy; Lakely, Bryce; Kollath, Lori; Brown, Lisha; Coleman, Ilsa; Coleman, Roger; Nguyen, Holly; Nelson, Peter S.; Corey, Eva; Snyder, Linda A.; Vessella, Robert L.; Morrissey, Colm; Lam, Hung-Ming

    2015-01-01

    Dissemination of prostate cancer (PCa) cells to the bone marrow is an early event in the disease process. In some patients, disseminated tumor cells (DTC) proliferate to form active metastases after a prolonged period of undetectable disease known as tumor dormancy. Identifying mechanisms of PCa dormancy and reactivation remain a challenge partly due to the lack of in vitro models. Here, we characterized in vitro PCa dormancy-reactivation by inducing cells from three patient-derived xenograft (PDX) lines to proliferate through tumor cell contact with each other and with bone marrow stroma. Proliferating PCa cells demonstrated tumor cell-cell contact and integrin clustering by immunofluorescence. Global gene expression analyses on proliferating cells cultured on bone marrow stroma revealed a downregulation of TGFB2 in all of the three proliferating PCa PDX lines when compared to their non-proliferating counterparts. Furthermore, constitutive activation of myosin light chain kinase (MLCK), a downstream effector of integrin-beta1 and TGF-beta2, in non-proliferating cells promoted cell proliferation. This cell proliferation was associated with an upregulation of CDK6 and a downregulation of E2F4. Taken together, our data provide the first clinically relevant in vitro model to support cellular adhesion and downregulation of TGFB2 as a potential mechanism by which PCa cells may escape from dormancy. Targeting the TGF-beta2-associated mechanism could provide novel opportunities to prevent lethal PCa metastasis. PMID:26090669

  20. Cell adhesion to fibronectin and tenascin: quantitative measurements of initial binding and subsequent strengthening response

    PubMed Central

    1989-01-01

    Cell-substratum adhesion strengths have been quantified using fibroblasts and glioma cells binding to two extracellular matrix proteins, fibronectin and tenascin. A centrifugal force-based adhesion assay was used for the adhesive strength measurements, and the corresponding morphology of the adhesions was visualized by interference reflection microscopy. The initial adhesions as measured at 4 degrees C were on the order of 10(-5)dynes/cell and did not involve the cytoskeleton. Adhesion to fibronectin after 15 min at 37 degrees C were more than an order of magnitude stronger; the strengthening response required cytoskeletal involvement. By contrast to the marked strengthening of adhesion to FN, adhesion to TN was unchanged or weakened after 15 min at 37 degrees C. The absolute strength of adhesion achieved varied according to protein and cell type. When a mixed substratum of fibronectin and tenascin was tested, the presence of tenascin was found to reduce the level of the strengthening of cell adhesion normally observed at 37 degrees C on a substratum of fibronectin alone. Parallel analysis of corresponding interference reflection micrographs showed that differences in the area of cell surface within 10-15 nm of the substratum correlated closely with each of the changes in adhesion observed: after incubation for 15 min on fibronectin at 37 degrees C, glioma cells increased their surface area within close contact to the substrate by integral to 125- fold. Cells on tenascin did not increase their surface area of contact. The increased surface area of contact and the inhibitory activity of cytochalasin b suggest that the adhesive "strengthening" in the 15 min after initial binding brings additional adhesion molecules into the adhesive site and couples the actin cytoskeleton to the adhesion complex. PMID:2477381

  1. Stroma Regulates Increased Epithelial Lateral Cell Adhesion in 3D Culture: A Role for Actin/Cadherin Dynamics

    PubMed Central

    Chambers, Karen F.; Pearson, Joanna F.; Aziz, Naveed; O'Toole, Peter; Garrod, David; Lang, Shona H.

    2011-01-01

    Background Cell shape and tissue architecture are controlled by changes to junctional proteins and the cytoskeleton. How tissues control the dynamics of adhesion and cytoskeletal tension is unclear. We have studied epithelial tissue architecture using 3D culture models and found that adult primary prostate epithelial cells grow into hollow acinus-like spheroids. Importantly, when co-cultured with stroma the epithelia show increased lateral cell adhesions. To investigate this mechanism further we aimed to: identify a cell line model to allow repeatable and robust experiments; determine whether or not epithelial adhesion molecules were affected by stromal culture; and determine which stromal signalling molecules may influence cell adhesion in 3D epithelial cell cultures. Methodology/Principal Findings The prostate cell line, BPH-1, showed increased lateral cell adhesion in response to stroma, when grown as 3D spheroids. Electron microscopy showed that 9.4% of lateral membranes were within 20 nm of each other and that this increased to 54% in the presence of stroma, after 7 days in culture. Stromal signalling did not influence E-cadherin or desmosome RNA or protein expression, but increased E-cadherin/actin co-localisation on the basolateral membranes, and decreased paracellular permeability. Microarray analysis identified several growth factors and pathways that were differentially expressed in stroma in response to 3D epithelial culture. The upregulated growth factors TGFβ2, CXCL12 and FGF10 were selected for further analysis because of previous associations with morphology. Small molecule inhibition of TGFβ2 signalling but not of CXCL12 and FGF10 signalling led to a decrease in actin and E-cadherin co-localisation and increased paracellular permeability. Conclusions/Significance In 3D culture models, paracrine stromal signals increase epithelial cell adhesion via adhesion/cytoskeleton interactions and TGFβ2-dependent mechanisms may play a key role. These

  2. Cytokine and adhesion molecule expression in primary human endothelial cells stimulated with fever-range hyperthermia.

    PubMed

    Shah, A; Unger, E; Bain, M D; Bruce, R; Bodkin, J; Ginnetti, J; Wang, W C; Seon, B; Stewart, C C; Evans, S S

    2002-01-01

    Migration of blood-borne lymphocytes into lymphoid tissues and sites of inflammation is initiated by vascular adhesion molecules and proinflammatory cytokines. Previous in vivo studies have shown that febrile temperatures dynamically stimulate adhesion in differentiated high endothelial venules (HEV), which are portals for lymphocyte extravasation. This report examines the direct effect of fever-range hyperthermia on the expression of adhesion molecules and cytokines by primary cultured endothelial cells. In both macrovascular (HUVEC) and microvascular (HMVEC) endothelial cells, fever-range hyperthermia (40 degrees C for 6-12 h) did not affect expression of adhesion molecules (ICAM-1, E-selectin, VCAM-1, P-selectin, PECAM-1, PNAd, MAdCAM-1), cytokine release (IL-1beta, TNF-alpha, IFN-gamma, IL-6, IL-11, IL-12, IL-13), or chemokine secretion (IL-8, RANTES, MCP-1, MIP-1beta, MIG). This is in contrast to the stimulatory effects of TNF-alpha or 43 degrees C heat shock. However, a novel role for fever-range hyperthermia was identified in augmenting actin polymerization in cultured endothelial cells and enhancing the ability of endothelial-derived factors to transactivate the alpha4beta7 integrin lymphocyte homing receptor. These findings provide insight into the tightly regulated effects of fever-range hyperthermia that exclude induction of adhesion in non-activated endothelium of normal blood vessels. Through these mechanisms, it is proposed that febrile temperatures associated with infection or clinical hyperthermia avoid the unproductive exodus of lymphocytes to non-involved extralymphoid tissues while simultaneously promoting lymphocyte delivery to sites of immune activation.

  3. Adhesion-Dependent Wave Generation in Crawling Cells.

    PubMed

    Barnhart, Erin L; Allard, Jun; Lou, Sunny S; Theriot, Julie A; Mogilner, Alex

    2017-01-09

    Dynamic actin networks are excitable. In migrating cells, feedback loops can amplify stochastic fluctuations in actin dynamics, often resulting in traveling waves of protrusion. The precise contributions of various molecular and mechanical interactions to wave generation have been difficult to disentangle, in part due to complex cellular morphodynamics. Here we used a relatively simple cell type-the fish epithelial keratocyte-to define a set of mechanochemical feedback loops underlying actin network excitability and wave generation. Although keratocytes are normally characterized by the persistent protrusion of a broad leading edge, increasing cell-substrate adhesion strength results in waving protrusion of a short leading edge. We show that protrusion waves are due to fluctuations in actin polymerization rates and that overexpression of VASP, an actin anti-capping protein that promotes actin polymerization, switches highly adherent keratocytes from waving to persistent protrusion. Moreover, VASP localizes both to adhesion complexes and to the leading edge. Based on these results, we developed a mathematical model for protrusion waves in which local depletion of VASP from the leading edge by adhesions-along with lateral propagation of protrusion due to the branched architecture of the actin network and negative mechanical feedback from the cell membrane-results in regular protrusion waves. Consistent with our model simulations, we show that VASP localization at the leading edge oscillates, with VASP leading-edge enrichment greatest just prior to protrusion initiation. We propose that the mechanochemical feedbacks underlying wave generation in keratocytes may constitute a general module for establishing excitable actin dynamics in other cellular contexts.

  4. Cell adhesion to cathodic arc plasma deposited CrAlSiN thin films

    NASA Astrophysics Data System (ADS)

    Kim, Sun Kyu; Pham, Vuong-Hung; Kim, Chong-Hyun

    2012-07-01

    Osteoblast cell response (cell adhesion, actin cytoskeleton and focal contact adhesion as well as cell proliferation) to CrN, CrAlSiN and Ti thin films was evaluated in vitro. Cell adhesion and actin stress fibers organization depended on the film composition significantly. Immunofluorescent staining of vinculin in osteoblast cells showed good focal contact adhesion on the CrAlSiN and Ti thin films but not on the CrN thin films. Cell proliferation was significantly greater on the CrAlSiN thin films as well as on Ti thin films than on the CrN thin films.

  5. Increase of β2-integrin on adhesion of THP-1 cells to collagen vitrigel membrane.

    PubMed

    Uchino, Tadashi; Kuroda, Yukie; Ishida, Seiichi; Yamashita, Kunihiko; Miyazaki, Hiroshi; Oshikata, Ayumi; Shimizu, Kumiko; Kojima, Hajime; Takezawa, Toshiaki; Akiyama, Takumi; Ikarashi, Yoshiaki

    2016-07-04

    When human monocyte-derived leukemia (THP-1) cells, which are floating cells, are stimulated with lipid peroxides, or Streptococcus suis, these cells adhere to a plastic plate or endothelial cells. However, it is unclear whether or not non-stimulated THP-1 cells adhere to collagen vitrigel membrane (CVM). In this study, firstly, we investigated the rate of adhesion of THP-1 cells to CVM. When THP-1 cells were not stimulated, the rate of adhesion to CVM was high. Then, to identify adhesion molecules involved in adhesion of THP-1 cells to CVM, expressions of various cell adhesion molecules on the surface of THP-1 cells adhering to CVM were measured. β-actin, β-catenin, and β1-integrin expressions did not change in non-stimulated THP-1 cells cultured on CVM compared with those in cells cultured in a flask, but β2-integrin expression markedly increased.

  6. ARAP3 inhibits peritoneal dissemination of scirrhous gastric carcinoma cells by regulating cell adhesion and invasion.

    PubMed

    Yagi, R; Tanaka, M; Sasaki, K; Kamata, R; Nakanishi, Y; Kanai, Y; Sakai, R

    2011-03-24

    During the analysis of phosphotyrosine-containing proteins in scirrhous gastric carcinoma cell lines, we observed an unusual expression of Arf-GAP with Rho-GAP domain, ankyrin repeat and PH domain 3 (ARAP3), a multimodular signaling protein that is a substrate of Src family kinases. Unlike other phosphotyrosine proteins, such as CUB domain-containing protein 1 (CDCP1) and Homo sapiens chromosome 9 open reading frame 10/oxidative stress-associated Src activator (C9orf10/Ossa), which are overexpressed and hyperphosphorylated in scirrhous gastric carcinoma cell lines, ARAP3 was underexpressed in cancerous human gastric tissues. In this study, we found that overexpression of ARAP3 in the scirrhous gastric carcinoma cell lines significantly reduced peritoneal dissemination. In vitro studies also showed that ARAP3 regulated cell attachment to the extracellular matrix, as well as invasive activities. These effects were suppressed by mutations in the Rho-GTPase-activating protein (GAP) domain or in the C-terminal two tyrosine residues that are phosphorylated by Src. Thus, the expression and phosphorylation state of ARAP3 may affect the invasiveness of cancer by modulating cell adhesion and motility. Our results suggest that ARAP3 is a unique Src substrate that suppresses peritoneal dissemination of scirrhous gastric carcinoma cells.

  7. Electric impedance sensing during the inhibition of cell-cell adhesion.

    PubMed

    Wiertz, R F; Rutten, W C; Marani, E

    2008-01-01

    Electric cell impedance sensing (ECIS) was used to monitor the change of in vitro neuron-neuron adhesion in response to the blocking of N-Cam, N-Cadherin and L1. ECIS is a method in which cell morphology and cell mobility can be indirectly measured by changes in intercellular resistance. Antibodies and soluble extracellular domains of the cell adhesion molecules N-Cam, N-Cadherin and L1 were used as blockers of these adhesion molecules on the cell surface. In a 96 hour aggregation assay on a low adhesive substrate, the effect of mentioned blockers on the aggregation was investigated. The N-Cadherin antibody showed effective in aggregation inhibition at concentrations of 3 and 10 micrograms/ml. Up to 96 hours no aggregation occurred. A similar effect was achieved by the N-Cadherin protein, although less distinct. Blocking of N-CAM and L1 revealed no inhibition of aggregation. Results from impedance measurements correspond to those of the aggregation assays. The neuron-neuron adhesion in monolayers was inhibited by blocking of cell adhesion molecules and monitored by ECIS. Impedances of neuron covered electrodes were significantly lower in the presence of N-Cadherin antibody and protein at concentrations of 1, 3 and 10 micrograms/ml, indicating a less profound binding between adjacent neuron.The results from both the aggregation assays and the impedance measurements demonstrate the applicability of CAM blocking for the regulation of culture topography.

  8. Cell adhesion and guidance by micropost-array chemical sensors

    NASA Astrophysics Data System (ADS)

    Pantano, Paul; Quah, Soo-Kim; Danowski, Kristine L.

    2002-06-01

    An array of ~50,000 individual polymeric micropost sensors was patterned across a glass coverslip by a photoimprint lithographic technique. Individual micropost sensors were ~3-micrometers tall and ~8-micrometers wide. The O2-sensitive micropost array sensors (MPASs) comprised a ruthenium complex encapsulated in a gas permeable photopolymerizable siloxane. The pH-sensitive MPASs comprised a fluorescein conjugate encapsulated in a photocrosslinkable poly(vinyl alcohol)-based polymer. PO2 and pH were quantitated by acquiring MPAS luminescence images with an epifluorescence microscope/charge coupled device imaging system. O2-sensitive MPASs displayed linear Stern-Volmer quenching behavior with a maximum Io/I of ~8.6. pH-sensitive MPASs displayed sigmoidal calibration curves with a pKa of ~5.8. The adhesion of undifferentiated rat pheochromocytoma (PC12) cells across these two polymeric surface types was investigated. The greatest PC12 cell proliferation and adhesion occurred across the poly(vinyl alcohol)-based micropost arrays relative to planar poly(vinyl alcohol)-based surfaces and both patterned and planar siloxane surfaces. An additional advantage of the patterned MPAS layers relative to planar sensing layers was the ability to direct the growth of biological cells. Preliminary data is presented whereby nerve growth factor-differentiated PC12 cells grew neurite-like processes that extended along paths defined by the micropost architecture.

  9. Nonlinear flow affects hydrodynamic forces and neutrophil adhesion rates in cone-plate viscometers.

    PubMed Central

    Shankaran, H; Neelamegham, S

    2001-01-01

    We present a theoretical and experimental analysis of the effects of nonlinear flow in a cone-plate viscometer. The analysis predicts that flow in the viscometer is a function of two parameters, the Reynolds number and the cone angle. Nonlinear flow occurs at high shear rates and causes spatial variations in wall shear stress, collision frequency, interparticle forces and attachment times within the viscometer. We examined the effect of these features on cellular adhesion kinetics. Based on recent data (Taylor, A. D., S. Neelamegham, J. D. Hell