Cellular level robotic surgery: Nanodissection of intermediate filaments in live keratinocytes.

PubMed

Yang, Ruiguo; Song, Bo; Sun, Zhiyong; Lai, King Wai Chiu; Fung, Carmen Kar Man; Patterson, Kevin C; Seiffert-Sinha, Kristina; Sinha, Animesh A; Xi, Ning

2015-01-01

We present the nanosurgery on the cytoskeleton of live cells using AFM based nanorobotics to achieve adhesiolysis and mimic the effect of pathophysiological modulation of intercellular adhesion. Nanosurgery successfully severs the intermediate filament bundles and disrupts cell-cell adhesion similar to the desmosomal protein disassembly in autoimmune disease, or the cationic modulation of desmosome formation. Our nanomechanical analysis revealed that adhesion loss results in a decrease in cellular stiffness in both cases of biochemical modulation of the desmosome junctions and mechanical disruption of intercellular adhesion, supporting the notion that intercellular adhesion through intermediate filaments anchors the cell structure as focal adhesion does and that intermediate filaments are integral components in cell mechanical integrity. The surgical process could potentially help reveal the mechanism of autoimmune pathology-induced cell-cell adhesion loss as well as its related pathways that lead to cell apoptosis. Copyright © 2015 Elsevier Inc. All rights reserved.

Intercellular adhesion molecule-1 expression by skeletal muscle cells augments myogenesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goh, Qingnian; Dearth, Christopher L.; Corbett, Jacob T.

We previously demonstrated that the expression of intercellular adhesion molecule-1 (ICAM-1) by skeletal muscle cells after muscle overload contributes to ensuing regenerative and hypertrophic processes in skeletal muscle. The objective of the present study is to reveal mechanisms through which skeletal muscle cell expression of ICAM-1 augments regenerative and hypertrophic processes of myogenesis. This was accomplished by genetically engineering C2C12 myoblasts to stably express ICAM-1, and by inhibiting the adhesive and signaling functions of ICAM-1 through the use of a neutralizing antibody or cell penetrating peptide, respectively. Expression of ICAM-1 by cultured skeletal muscle cells augmented myoblast–myoblast adhesion, myotube formation,more » myonuclear number, myotube alignment, myotube–myotube fusion, and myotube size without influencing the ability of myoblasts to proliferate or differentiate. ICAM-1 augmented myotube formation, myonuclear accretion, and myotube alignment through a mechanism involving adhesion-induced activation of ICAM-1 signaling, as these dependent measures were reduced via antibody and peptide inhibition of ICAM-1. The adhesive and signaling functions of ICAM-1 also facilitated myotube hypertrophy through a mechanism involving myotube–myotube fusion, protein synthesis, and Akt/p70s6k signaling. Our findings demonstrate that ICAM-1 expression by skeletal muscle cells augments myogenesis, and establish a novel mechanism through which the inflammatory response facilitates growth processes in skeletal muscle. - Highlights: • We examined mechanisms through which skeletal muscle cell expression of ICAM-1 facilitates events of in vitro myogenesis. • Expression of ICAM-1 by cultured myoblasts did not influence their ability to proliferate or differentiate. • Skeletal muscle cell expression of ICAM-1 augmented myoblast fusion, myotube alignment, myotube–myotube fusion, and myotube size. • ICAM-1 augmented myogenic processes through mechanisms involving its adhesive and signaling functions.« less

Holding Tight: Cell Junctions and Cancer Spread.

PubMed

Knights, Alexander J; Funnell, Alister P W; Crossley, Merlin; Pearson, Richard C M

2012-01-01

Cell junctions are sites of intercellular adhesion that maintain the integrity of epithelial tissue and regulate signalling between cells. These adhesive junctions are comprised of protein complexes that serve to establish an intercellular cytoskeletal network for anchoring cells, in addition to regulating cell polarity, molecular transport and communication. The expression of cell adhesion molecules is tightly controlled and their downregulation is essential for epithelial-mesenchymal transition (EMT), a process that facilitates the generation of morphologically and functionally diverse cell types during embryogenesis. The characteristics of EMT are a loss of cell adhesion and increased cellular mobility. Hence, in addition to its normal role in development, dysregulated EMT has been linked to cancer progression and metastasis, the process whereby primary tumors migrate to invasive secondary sites in the body. This paper will review the current understanding of cell junctions and their role in cancer, with reference to the abnormal regulation of junction protein genes. The potential use of cell junction molecules as diagnostic and prognostic markers will also be discussed, as well as possible therapies for adhesive dysregulation.

Nanowell-Trapped Charged Ligand-Bearing Nanoparticle Surfaces – A Novel Method of Enhancing Flow-Resistant Cell Adhesion

PubMed Central

Tran, Phat L.; Gamboa, Jessica R.; McCracken, Katherine E.; Riley, Mark R.

2014-01-01

Assuring cell adhesion to an underlying biomaterial surface is vital in implant device design and tissue engineering, particularly under circumstances where cells are subjected to potential detachment from overriding fluid flow. Cell-substrate adhesion is a highly regulated process involving the interplay of mechanical properties, surface topographic features, electrostatic charge, and biochemical mechanisms. At the nanoscale level the physical properties of the underlying substrate are of particular importance in cell adhesion. Conventionally, natural, pro-adhesive, and often thrombogenic, protein biomaterials are frequently utilized to facilitate adhesion. In the present study nanofabrication techniques are utilized to enhance the biological functionality of a synthetic polymer surface, polymethymethacrylate, with respect to cell adhesion. Specifically we examine the effect on cell adhesion of combining: 1. optimized surface texturing, 2. electrostatic charge and 3. cell adhesive ligands, uniquely assembled on the substrata surface, as an ensemble of nanoparticles trapped in nanowells. Our results reveal that the ensemble strategy leads to enhanced, more than simply additive, endothelial cell adhesion under both static and flow conditions. This strategy may be of particular utility for enhancing flow-resistant endothelialization of blood-contacting surfaces of cardiovascular devices subjected to flow-mediated shear. PMID:23225491

Design rules for biomolecular adhesion: lessons from force measurements.

PubMed

Leckband, Deborah

2010-01-01

Cell adhesion to matrix, other cells, or pathogens plays a pivotal role in many processes in biomolecular engineering. Early macroscopic methods of quantifying adhesion led to the development of quantitative models of cell adhesion and migration. The more recent use of sensitive probes to quantify the forces that alter or manipulate adhesion proteins has revealed much greater functional diversity than was apparent from population average measurements of cell adhesion. This review highlights theoretical and experimental methods that identified force-dependent molecular properties that are central to the biological activity of adhesion proteins. Experimental and theoretical methods emphasized in this review include the surface force apparatus, atomic force microscopy, and vesicle-based probes. Specific examples given illustrate how these tools have revealed unique properties of adhesion proteins and their structural origins.

Application of Organosilane Monolayer Template to Quantitative Evaluation of Cancer Cell Adhesive Ability

NASA Astrophysics Data System (ADS)

Tanii, Takashi; Sasaki, Kosuke; Ichisawa, Kota; Demura, Takanori; Beppu, Yuichi; Vu, Hoan Anh; Thanh Chi, Hoan; Yamamoto, Hideaki; Sato, Yuko

2011-06-01

The adhesive ability of two human pancreatic cancer cell lines was evaluated using organosilane monolayer templates (OMTs). Using the OMT, the spreading area of adhered cells can be limited, and this enables us to focus on the initial attachment process of adhesion. Moreover, it becomes possible to arrange the cells in an array and to quantitatively evaluate the number of attached cells. The adhesive ability of the cancer cells cultured on the OMT was controlled by adding (-)-epigallocatechin-3-gallate (EGCG), which blocks a receptor that mediates cell adhesion and is overexpressed in cancer cells. Measurement of the relative ability of the cancer cells to attach to the OMT revealed that the ability for attachment decreased with increasing EGCG concentration. The results agreed well with the western blot analysis, indicating that the OMT can potentially be employed to evaluate the adhesive ability of various cancer cells.

Rac-WAVE-mediated actin reorganization is required for organization and maintenance of cell-cell adhesion.

PubMed

Yamazaki, Daisuke; Oikawa, Tsukasa; Takenawa, Tadaomi

2007-01-01

During cadherin-dependent cell-cell adhesion, the actin cytoskeleton undergoes dynamic reorganization in epithelial cells. Rho-family small GTPases, which regulate actin dynamics, play pivotal roles in cadherin-dependent cell-cell adhesion; however, the precise molecular mechanisms that underlie cell-cell adhesion formation remain unclear. Here we show that Wiskott-Aldrich syndrome protein family verprolin-homologous protein (WAVE)-mediated reorganization of actin, downstream of Rac plays an important role in normal development of cadherin-dependent cell-cell adhesions in MDCK cells. Rac-induced development of cadherin-dependent adhesions required WAVE2-dependent actin reorganization. The process of cell-cell adhesion is divided into three steps: formation of new cell-cell contacts, stabilization of these new contacts and junction maturation. WAVE1 and WAVE2 were expressed in MDCK cells. The functions of WAVE1 and WAVE2 were redundant in this system but WAVE2 appeared to play a more significant role. During the first step, WAVE2-dependent lamellipodial protrusions facilitated formation of cell-cell contacts. During the second step, WAVE2 recruited actin filaments to new cell-cell contacts and stabilized newly formed cadherin clusters. During the third step, WAVE2-dependent actin reorganization was required for organization and maintenance of mature cell-cell adhesions. Thus, Rac-WAVE-dependent actin reorganization is not only involved in formation of cell-cell adhesions but is also required for their maintenance.

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 loss of control through the local environment can promote tumour cell dissemination. This article was reviewed by Hanspeter Herzel, Thomas Dandekar and Marek Kimmel.

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.

Annexin A6 contributes to the invasiveness of breast carcinoma cells by influencing the organization and localization of functional focal adhesions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sakwe, Amos M., E-mail: asakwe@mmc.edu; Koumangoye, Rainelli; Guillory, Bobby

2011-04-01

The interaction of annexin A6 (AnxA6) with membrane phospholipids and either specific extracellular matrix (ECM) components or F-actin suggests that it may influence cellular processes associated with rapid plasma membrane reorganization such as cell adhesion and motility. Here, we examined the putative roles of AnxA6 in adhesion-related cellular processes that contribute to breast cancer progression. We show that breast cancer cells secrete annexins via the exosomal pathway and that the secreted annexins are predominantly cell surface-associated. Depletion of AnxA6 in the invasive BT-549 breast cancer cells is accompanied by enhanced anchorage-independent cell growth but cell-cell cohesion, cell adhesion/spreading onto collagenmore » type IV or fetuin-A, cell motility and invasiveness were strongly inhibited. To explain the loss in adhesion/motility, we show that vinculin-based focal adhesions in the AnxA6-depleted BT-549 cells are elongated and randomly distributed. These focal contacts are also functionally defective because the activation of focal adhesion kinase and the phosphoinositide-3 kinase/Akt pathway were strongly inhibited while the MAP kinase pathway remained constitutively active. Compared with normal human breast tissues, reduced AnxA6 expression in breast carcinoma tissues correlates with enhanced cell proliferation. Together this suggests that reduced AnxA6 expression contributes to breast cancer progression by promoting the loss of functional cell-cell and/or cell-ECM contacts and anchorage-independent cell proliferation.« less

The conveyor belt hypothesis for thymocyte migration: participation of adhesion and de-adhesion molecules.

PubMed

Villa-Verde, D M; Calado, T C; Ocampo, J S; Silva-Monteiro, E; Savino, W

1999-05-01

Thymocyte differentiation is the process by which bone marrow-derived precursors enter the thymus, proliferate, rearrange the genes and express the corresponding T cell receptors, and undergo positive and/or negative selection, ultimately yielding mature T cells that will represent the so-called T cell repertoire. This process occurs in the context of cell migration, whose cellular and molecular basis is still poorly understood. Kinetic studies favor the idea that these cells leave the organ in an ordered pattern, as if they were moving on a conveyor belt. We have recently proposed that extracellular matrix glycoproteins, such as fibronectin, laminin and type IV collagen, among others, produced by non-lymphoid cells both in the cortex and in the medulla, would constitute a macromolecular arrangement allowing differentiating thymocytes to migrate. Here we discuss the participation of both molecules with adhesive and de-adhesive properties in the intrathymic T cell migration. Functional experiments demonstrated that galectin-3, a soluble beta-galactoside-binding lectin secreted by thymic microenvironmental cells, is a likely candidate for de-adhesion proteins by decreasing thymocyte interaction with the thymic microenvironment.

Angiogenesis mediated by soluble forms of E-selectin and vascular cell adhesion molecule-1

NASA Astrophysics Data System (ADS)

Koch, Alisa E.; Halloran, Margaret M.; Haskell, Catherine J.; Shah, Manisha R.; Polverini, Peter J.

1995-08-01

ENDOTHELIAL adhesion molecules facilitate the entry of leukocytes into inflamed tissues. This in turn promotes neovascularization, a process central to the progression of rheumatoid arthritis, tumour growth and wound repair1. Here we test the hypothesis that soluble endothelial adhesion molecules promote angiogenesis2á¤-4. Human recombinant soluble E-selectin and soluble vascular cell adhesion molecule-1 induced chemotaxis of human endothelial cells in vitro and were angiogenic in rat cornea. Soluble E-selectin acted on endothelial cells in part through a sialyl Lewis-X-dependent mechanism, while soluble vascular cell adhesion molecule-1 acted on endothelial cells in part through a very late antigen (VLA)-4 dependent mechanism. The chemotactic activity of rheumatoid synovial fluid for endothelial cells, and also its angiogenic activity, were blocked by antibodies to either soluble E-selectin or soluble vascular cell adhesion molecule-1. These results suggest a novel function for soluble endothelial adhesion molecules as mediators of angiogenesis.

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 effective drug carriers for delivery of therapeutic agents to afflicted sites of the host.

Ephrin-A1/EphA4-mediated adhesion of monocytes to endothelial cells.

PubMed

Jellinghaus, Stefanie; Poitz, David M; Ende, Georg; Augstein, Antje; Weinert, Sönke; Stütz, Beryl; Braun-Dullaeus, Rüdiger C; Pasquale, Elena B; Strasser, Ruth H

2013-10-01

The Eph receptors represent the largest family of receptor tyrosine kinases. Both Eph receptors and their ephrin ligands are cell-surface proteins, and they typically mediate cell-to-cell communication by interacting at sites of intercellular contact. The major aim of the present study was to investigate the involvement of EphA4-ephrin-A1 interaction in monocyte adhesion to endothelial cells, as this process is a crucial step during the initiation and progression of the atherosclerotic plaque. Immunohistochemical analysis of human atherosclerotic plaques revealed expression of EphA4 receptor and ephrin-A1 ligand in major cell types within the plaque. Short-time stimulation of endothelial cells with the soluble ligand ephrin-A1 leads to a fourfold increase in adhesion of human monocytes to endothelial cells. In addition, ephrin-A1 further increases monocyte adhesion to already inflamed endothelial cells. EphrinA1 mediates its effect on monocyte adhesion via the activated receptor EphA4. This ephrinA1/EphA4 induced process involves the activation of the Rho signaling pathway and does not require active transcription. Rho activation downstream of EphA4 leads to increased polymerization of actin filaments in endothelial cells. This process was shown to be crucial for the proadhesive effect of ephrin-A1. The results of the present study show that ephrin-A1-induced EphA4 forward signaling promotes monocyte adhesion to endothelial cells via activation of RhoA and subsequent stress-fiber formation by a non-transcriptional mechanism. Copyright © 2013 Elsevier B.V. All rights reserved.

Intercellular adhesion molecule-1 expression by skeletal muscle cells augments myogenesis.

PubMed

Goh, Qingnian; Dearth, Christopher L; Corbett, Jacob T; Pierre, Philippe; Chadee, Deborah N; Pizza, Francis X

2015-02-15

We previously demonstrated that the expression of intercellular adhesion molecule-1 (ICAM-1) by skeletal muscle cells after muscle overload contributes to ensuing regenerative and hypertrophic processes in skeletal muscle. The objective of the present study is to reveal mechanisms through which skeletal muscle cell expression of ICAM-1 augments regenerative and hypertrophic processes of myogenesis. This was accomplished by genetically engineering C2C12 myoblasts to stably express ICAM-1, and by inhibiting the adhesive and signaling functions of ICAM-1 through the use of a neutralizing antibody or cell penetrating peptide, respectively. Expression of ICAM-1 by cultured skeletal muscle cells augmented myoblast-myoblast adhesion, myotube formation, myonuclear number, myotube alignment, myotube-myotube fusion, and myotube size without influencing the ability of myoblasts to proliferate or differentiate. ICAM-1 augmented myotube formation, myonuclear accretion, and myotube alignment through a mechanism involving adhesion-induced activation of ICAM-1 signaling, as these dependent measures were reduced via antibody and peptide inhibition of ICAM-1. The adhesive and signaling functions of ICAM-1 also facilitated myotube hypertrophy through a mechanism involving myotube-myotube fusion, protein synthesis, and Akt/p70s6k signaling. Our findings demonstrate that ICAM-1 expression by skeletal muscle cells augments myogenesis, and establish a novel mechanism through which the inflammatory response facilitates growth processes in skeletal muscle. Copyright © 2014 Elsevier Inc. All rights reserved.

Intercellular Adhesion Molecule-1 Expression by Skeletal Muscle Cells Augments Myogenesis

PubMed Central

Goh, Qingnian; Dearth, Christopher L.; Corbett, Jacob T.; Pierre, Philippe; Chadee, Deborah N.; Pizza, Francis X.

2014-01-01

We previously demonstrated that the expression of intercellular adhesion molecule-1 (ICAM-1) by skeletal muscle cells after muscle overload contributes to ensuing regenerative and hypertrophic processes in skeletal muscle. The objective of the present study is to reveal mechanisms through which skeletal muscle cell expression of ICAM-1 augments regenerative and hypertrophic processes of myogenesis. This was accomplished by genetically engineering C2C12 myoblasts to stably express ICAM-1, and by inhibiting the adhesive and signaling functions of ICAM-1 through the use of a neutralizing antibody or cell penetrating peptide, respectively. Expression of ICAM-1 by cultured skeletal muscle cells augmented myoblast-myoblast adhesion, myotube formation, myonuclear number, myotube alignment, myotube-myotube fusion, and myotube size without influencing the ability of myoblasts to proliferate or differentiate. ICAM-1 augmented myotube formation, myonuclear accretion, and myotube alignment through a mechanism involving adhesion-induced activation of ICAM-1 signaling, as these dependent measures were reduced via antibody and peptide inhibition of ICAM-1. The adhesive and signaling functions of ICAM-1 also facilitated myotube hypertrophy through a mechanism involving myotube-myotube fusion, protein synthesis, and Akt/p70s6k signaling. Our findings demonstrate that ICAM-1 expression by skeletal muscle cells augments myogenesis, and establish a novel mechanism through which the inflammatory response facilitates growth processes in skeletal muscle. PMID:25281303

Modeling the formation of cell-matrix adhesions on a single 3D matrix fiber.

PubMed

Escribano, J; Sánchez, M T; García-Aznar, J M

2015-11-07

Cell-matrix adhesions are crucial in different biological processes like tissue morphogenesis, cell motility, and extracellular matrix remodeling. These interactions that link cell cytoskeleton and matrix fibers are built through protein clutches, generally known as adhesion complexes. The adhesion formation process has been deeply studied in two-dimensional (2D) cases; however, the knowledge is limited for three-dimensional (3D) cases. In this work, we simulate different local extracellular matrix properties in order to unravel the fundamental mechanisms that regulate the formation of cell-matrix adhesions in 3D. We aim to study the mechanical interaction of these biological structures through a three dimensional discrete approach, reproducing the transmission pattern force between the cytoskeleton and a single extracellular matrix fiber. This numerical model provides a discrete analysis of the proteins involved including spatial distribution, interaction between them, and study of the different phenomena, such as protein clutches unbinding or protein unfolding. Copyright © 2015 Elsevier Ltd. All rights reserved.

High aspect ratio silicon nanowires control fibroblast adhesion and cytoskeleton organization

NASA Astrophysics Data System (ADS)

Andolfi, Laura; Murello, Anna; Cassese, Damiano; Ban, Jelena; Dal Zilio, Simone; Lazzarino, Marco

2017-04-01

Cell-cell and cell-matrix interactions are essential to the survival and proliferation of most cells, and are responsible for triggering a wide range of biochemical pathways. More recently, the biomechanical role of those interactions was highlighted, showing, for instance, that adhesion forces are essential for cytoskeleton organization. Silicon nanowires (Si NWs) with their small size, high aspect ratio and anisotropic mechanical response represent a useful model to investigate the forces involved in the adhesion processes and their role in cellular development. In this work we explored and quantified, by single cell force spectroscopy (SCFS), the interaction of mouse embryonic fibroblasts with a flexible forest of Si NWs. We observed that the cell adhesion forces are comparable to those found on collagen and bare glass coverslip, analogously the membrane tether extraction forces are similar to that on collagen but stronger than that on bare flat glass. Cell survival did not depend significantly on the substrate, although a reduced proliferation after 36 h was observed. On the contrary both cell morphology and cytoskeleton organization revealed striking differences. The cell morphology on Si-NW was characterized by a large number of filopodia and a significant decrease of the cell mobility. The cytoskeleton organization was characterized by the absence of actin fibers, which were instead dominant on collagen and flat glass support. Such findings suggest that the mechanical properties of disordered Si NWs, and in particular their strong asymmetry, play a major role in the adhesion, morphology and cytoskeleton organization processes. Indeed, while adhesion measurements by SCFS provide out-of-plane forces values consistent with those measured on conventional substrates, weaker in-plane forces hinder proper cytoskeleton organization and migration processes.

High aspect ratio silicon nanowires control fibroblast adhesion and cytoskeleton organization.

PubMed

Andolfi, Laura; Murello, Anna; Cassese, Damiano; Ban, Jelena; Dal Zilio, Simone; Lazzarino, Marco

2017-04-18

Cell-cell and cell-matrix interactions are essential to the survival and proliferation of most cells, and are responsible for triggering a wide range of biochemical pathways. More recently, the biomechanical role of those interactions was highlighted, showing, for instance, that adhesion forces are essential for cytoskeleton organization. Silicon nanowires (Si NWs) with their small size, high aspect ratio and anisotropic mechanical response represent a useful model to investigate the forces involved in the adhesion processes and their role in cellular development. In this work we explored and quantified, by single cell force spectroscopy (SCFS), the interaction of mouse embryonic fibroblasts with a flexible forest of Si NWs. We observed that the cell adhesion forces are comparable to those found on collagen and bare glass coverslip, analogously the membrane tether extraction forces are similar to that on collagen but stronger than that on bare flat glass. Cell survival did not depend significantly on the substrate, although a reduced proliferation after 36 h was observed. On the contrary both cell morphology and cytoskeleton organization revealed striking differences. The cell morphology on Si-NW was characterized by a large number of filopodia and a significant decrease of the cell mobility. The cytoskeleton organization was characterized by the absence of actin fibers, which were instead dominant on collagen and flat glass support. Such findings suggest that the mechanical properties of disordered Si NWs, and in particular their strong asymmetry, play a major role in the adhesion, morphology and cytoskeleton organization processes. Indeed, while adhesion measurements by SCFS provide out-of-plane forces values consistent with those measured on conventional substrates, weaker in-plane forces hinder proper cytoskeleton organization and migration processes.

Fermented soya bean (tempe) extracts reduce adhesion of enterotoxigenic Escherichia coli to intestinal epithelial cells.

PubMed

Roubos-van den Hil, P J; Nout, M J R; Beumer, R R; van der Meulen, J; Zwietering, M H

2009-03-01

This study aimed to investigate the effect of processed soya bean, during the successive stages of tempe fermentation and different fermentation times, on adhesion of enterotoxigenic Escherichia coli (ETEC) K88 to intestinal brush border cells as well as Caco-2 intestinal epithelial cells; and to clarify the mechanism of action. Tempe was prepared at controlled laboratory scale using Rhizopus microsporus var. microsporus as the inoculum. Extracts of raw, soaked and cooked soya beans reduced ETEC adhesion to brush border cells by 40%. Tempe extracts reduced adhesion by 80% or more. ETEC adhesion to Caco-2 cells reduced by 50% in the presence of tempe extracts. ETEC K88 bacteria were found to interact with soya bean extracts, and this may contribute to the observed decrease of ETEC adhesion to intestinal epithelial cells. Fermented soya beans (tempe) reduce the adhesion of ETEC to intestinal epithelial cells of pig and human origin. This reduced adhesion is caused by an interaction between ETEC K88 bacteria and soya bean compounds. The results strengthen previous observations on the anti-diarrhoeal effect of tempe. This effect indicates that soya-derived compounds may reduce adhesion of ETEC to intestinal cells in pigs as well as in humans and prevent against diarrhoeal diseases.

Impacts of icodextrin on integrin-mediated wound healing of peritoneal mesothelial cells.

PubMed

Matsumoto, Mika; Tamura, Masahito; Miyamoto, Tetsu; Furuno, Yumi; Kabashima, Narutoshi; Serino, Ryota; Shibata, Tatsuya; Kanegae, Kaori; Takeuchi, Masaaki; Abe, Haruhiko; Okazaki, Masahiro; Otsuji, Yutaka

2012-06-14

Exposure to glucose and its metabolites in peritoneal dialysis fluid (PDF) results in structural alterations of the peritoneal membrane. Icodextrin-containing PDF eliminates glucose and reduces deterioration of peritoneal membrane function, but direct effects of icodextrin molecules on peritoneal mesothelial cells have yet to be elucidated. We compared the impacts of icodextrin itself with those of glucose under PDF-free conditions on wound healing processes of injured mesothelial cell monolayers, focusing on integrin-mediated cell adhesion mechanisms. Regeneration processes of the peritoneal mesothelial cell monolayer were investigated employing an in vitro wound healing assay of cultured rat peritoneal mesothelial cells treated with icodextrin powder- or glucose-dissolved culture medium without PDF, as well as icodextrin- or glucose-containing PDF. The effects of icodextrin on integrin-mediated cell adhesions were examined by immunocytochemistry and Western blotting against focal adhesion kinase (FAK). Cell migration over fibronectin was inhibited in conventional glucose-containing PDF, while icodextrin-containing PDF exerted no significant inhibitory effects. Culture medium containing 1.5% glucose without PDF also inhibited wound healing of mesothelial cells, while 7.5% icodextrin-dissolved culture medium without PDF had no inhibitory effects. Glucose suppressed cell motility by inhibiting tyrosine phosphorylation of FAK, formation of focal adhesions, and cell spreading, while icodextrin had no effects on any of these mesothelial cell functions. Our results demonstrate icodextrin to have no adverse effects on wound healing processes of peritoneal mesothelial cells. Preservation of integrin-mediated cell adhesion might be one of the molecular mechanisms accounting for the superior biocompatibility of icodextrin-containing PDF. Copyright © 2012 Elsevier Inc. All rights reserved.

Adhesion of leukocytes under oscillating stagnation point conditions: a numerical study.

PubMed

Walker, P G; Alshorman, A A; Westwood, S; David, T

2002-01-01

Leukocyte recruitment from blood to the endothelium plays an important role in atherosclerotic plaque formation. Cells show a primary and secondary adhesive process with primary bonds responsible for capture and rolling and secondary bonds for arrest. Our objective was to investigate the role played by this process on the adhesion of leukocytes in complex flow. Cells were modelled as rigid spheres with spring like adhesion molecules which formed bonds with endothelial receptors. Models of bond kinetics and Newton's laws of motion were solved numerically to determine cell motion. Fluid force was obtained from the local shear rate obtained from a CFD simulation of the flow over a backward facing step.In stagnation point flow the shear rate near the stagnation point has a large gradient such that adherent cells in this region roll to a high shear region preventing permanent adhesion. This is enhanced if a small time dependent perturbation is imposed upon the stagnation point. For lower shear rates the cell rolling velocity may be such that secondary bonds have time to form. These bonds resist the lower fluid forces and consequently there is a relatively large permanent adhesion region.

Opto-acoustic microscopy reveals adhesion mechanics of single cells

NASA Astrophysics Data System (ADS)

Abi Ghanem, Maroun; Dehoux, Thomas; Liu, Liwang; Le Saux, Guillaume; Plawinski, Laurent; Durrieu, Marie-Christine; Audoin, Bertrand

2018-01-01

Laser-generated GHz-ultrasonic-based technologies have shown the ability to image single cell adhesion and stiffness simultaneously. Using this new modality, we here demonstrate quantitative indicators to investigate contact mechanics and adhesion processes of the cell. We cultured human cells on a rigid substrate, and we used an inverted pulsed opto-acoustic microscope to generate acoustic pulses containing frequencies up to 100 GHz in the substrate. We map the reflection of the acoustic pulses at the cell-substrate interface to obtain images of the acoustic impedance of the cell, Zc, as well as of the stiffness of the interface, K, with 1 μm lateral resolution. Our results show that the standard deviation ΔZc reveals differences between different cell types arising from the multiplicity of local conformations within the nucleus. From the distribution of K-values within the nuclear region, we extract a mean interfacial stiffness, Km, that quantifies the average contact force in areas of the cell displaying weak bonding. By analogy with classical contact mechanics, we also define the ratio of the real to nominal contact areas, Sr/St. We show that Km can be interpreted as a quantitative indicator of passive contact at metal-cell interfaces, while Sr/St is sensitive to active adhesive processes in the nuclear region. The ability to separate the contributions of passive and active adhesion processes should allow gaining insight into cell-substrate interactions, with important applications in tissue engineering.

Opto-acoustic microscopy reveals adhesion mechanics of single cells.

PubMed

Abi Ghanem, Maroun; Dehoux, Thomas; Liu, Liwang; Le Saux, Guillaume; Plawinski, Laurent; Durrieu, Marie-Christine; Audoin, Bertrand

2018-01-01

Laser-generated GHz-ultrasonic-based technologies have shown the ability to image single cell adhesion and stiffness simultaneously. Using this new modality, we here demonstrate quantitative indicators to investigate contact mechanics and adhesion processes of the cell. We cultured human cells on a rigid substrate, and we used an inverted pulsed opto-acoustic microscope to generate acoustic pulses containing frequencies up to 100 GHz in the substrate. We map the reflection of the acoustic pulses at the cell-substrate interface to obtain images of the acoustic impedance of the cell, Z c , as well as of the stiffness of the interface, K, with 1 μm lateral resolution. Our results show that the standard deviation ΔZ c reveals differences between different cell types arising from the multiplicity of local conformations within the nucleus. From the distribution of K-values within the nuclear region, we extract a mean interfacial stiffness, K m , that quantifies the average contact force in areas of the cell displaying weak bonding. By analogy with classical contact mechanics, we also define the ratio of the real to nominal contact areas, S r /S t . We show that K m can be interpreted as a quantitative indicator of passive contact at metal-cell interfaces, while S r /S t is sensitive to active adhesive processes in the nuclear region. The ability to separate the contributions of passive and active adhesion processes should allow gaining insight into cell-substrate interactions, with important applications in tissue engineering.

Role of flexural stiffness of leukocyte microvilli in adhesion dynamics

NASA Astrophysics Data System (ADS)

Wu, Tai-Hsien; Qi, Dewei

2018-03-01

Previous work reported that microvillus deformation has an important influence on dynamics of cell adhesion. However, the existing studies were limited to the extensional deformation of microvilli and did not consider the effects of their bending deformation on cell adhesion. This Rapid Communication investigates the effects of flexural stiffness of microvilli on the rolling process related to adhesion of leukocytes by using a lattice-Boltzmann lattice-spring method (LLM) combined with adhesive dynamics (AD) simulations. The simulation results reveal that the flexural stiffness of microvilli and their bending deformation have a profound effect on rolling velocity and adhesive forces. As the flexural stiffness of the microvilli decreases, their bending angles increase, resulting in an increase in the number of receptor-ligand bonds and adhesive bonding force and a decrease in the rolling velocity of leukocytes. The effects of flexural stiffness on deformation and adhesion represent crucial factors involved in cell adhesion.

Bacteria as living patchy colloids: Phenotypic heterogeneity in surface adhesion

PubMed Central

Hermes, Michiel; Schwarz-Linek, Jana; Poon, Wilson C. K.

2018-01-01

Understanding and controlling the surface adhesion of pathogenic bacteria is of urgent biomedical importance. However, many aspects of this process remain unclear (for example, microscopic details of the initial adhesion and possible variations between individual cells). Using a new high-throughput method, we identify and follow many single cells within a clonal population of Escherichia coli near a glass surface. We find strong phenotypic heterogeneities: A fraction of the cells remain in the free (planktonic) state, whereas others adhere with an adhesion strength that itself exhibits phenotypic heterogeneity. We explain our observations using a patchy colloid model; cells bind with localized, adhesive patches, and the strength of adhesion is determined by the number of patches: Nonadherers have no patches, weak adherers bind with a single patch only, and strong adherers bind via a single or multiple patches. We discuss possible implications of our results for controlling bacterial adhesion in biomedical and other applications. PMID:29719861

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).

Urokinase links plasminogen activation and cell adhesion by cleavage of the RGD motif in vitronectin.

PubMed

De Lorenzi, Valentina; Sarra Ferraris, Gian Maria; Madsen, Jeppe B; Lupia, Michela; Andreasen, Peter A; Sidenius, Nicolai

2016-07-01

Components of the plasminogen activation system including urokinase (uPA), its inhibitor (PAI-1) and its cell surface receptor (uPAR) have been implicated in a wide variety of biological processes related to tissue homoeostasis. Firstly, the binding of uPA to uPAR favours extracellular proteolysis by enhancing cell surface plasminogen activation. Secondly, it promotes cell adhesion and signalling through binding of the provisional matrix protein vitronectin. We now report that uPA and plasmin induces a potent negative feedback on cell adhesion through specific cleavage of the RGD motif in vitronectin. Cleavage of vitronectin by uPA displays a remarkable receptor dependence and requires concomitant binding of both uPA and vitronectin to uPAR Moreover, we show that PAI-1 counteracts the negative feedback and behaves as a proteolysis-triggered stabilizer of uPAR-mediated cell adhesion to vitronectin. These findings identify a novel and highly specific function for the plasminogen activation system in the regulation of cell adhesion to vitronectin. The cleavage of vitronectin by uPA and plasmin results in the release of N-terminal vitronectin fragments that can be detected in vivo, underscoring the potential physiological relevance of the process. © 2016 The Authors.

Mena binds α5 integrin directly and modulates α5β1 function.

PubMed

Gupton, Stephanie L; Riquelme, Daisy; Hughes-Alford, Shannon K; Tadros, Jenny; Rudina, Shireen S; Hynes, Richard O; Lauffenburger, Douglas; Gertler, Frank B

2012-08-20

Mena is an Ena/VASP family actin regulator with roles in cell migration, chemotaxis, cell-cell adhesion, tumor cell invasion, and metastasis. Although enriched in focal adhesions, Mena has no established function within these structures. We find that Mena forms an adhesion-regulated complex with α5β1 integrin, a fibronectin receptor involved in cell adhesion, motility, fibronectin fibrillogenesis, signaling, and growth factor receptor trafficking. Mena bound directly to the carboxy-terminal portion of the α5 cytoplasmic tail via a 91-residue region containing 13 five-residue "LERER" repeats. In fibroblasts, the Mena-α5 complex was required for "outside-in" α5β1 functions, including normal phosphorylation of FAK and paxillin and formation of fibrillar adhesions. It also supported fibrillogenesis and cell spreading and controlled cell migration speed. Thus, fibroblasts require Mena for multiple α5β1-dependent processes involving bidirectional interactions between the extracellular matrix and cytoplasmic focal adhesion proteins.

The CD44-initiated pathway of T-cell extravasation uses VLA-4 but not LFA-1 for firm adhesion

PubMed Central

Siegelman, Mark H.; Stanescu, Diana; Estess, Pila

2000-01-01

Leukocytes extravasate from the blood in response to physiologic or pathologic demands by means of complementary ligand interactions between leukocytes and endothelial cells. The multistep model of leukocyte extravasation involves an initial transient interaction (“rolling” adhesion), followed by secondary (firm) adhesion. We recently showed that binding of CD44 on activated T lymphocytes to endothelial hyaluronan (HA) mediates a primary adhesive interaction under shear stress, permitting extravasation at sites of inflammation. The mechanism for subsequent firm adhesion has not been elucidated. Here we demonstrate that the integrin VLA-4 is used in secondary adhesion after CD44-mediated primary adhesion of human and mouse T cells in vitro, and by mouse T cells in an in vivo model. We show that clonal cell lines and polyclonally activated normal T cells roll under physiologic shear forces on hyaluronate and require VCAM-1, but not ICAM-1, as ligand for subsequent firm adhesion. This firm adhesion is also VLA-4 dependent, as shown by antibody inhibition. Moreover, in vivo short-term homing experiments in a model dependent on CD44 and HA demonstrate that superantigen-activated T cells require VLA-4, but not LFA-1, for entry into an inflamed peritoneal site. Thus, extravasation of activated T cells initiated by CD44 binding to HA depends upon VLA-4–mediated firm adhesion, which may explain the frequent association of these adhesion receptors with diverse chronic inflammatory processes. PMID:10712440

Tension and Elasticity Contribute to Fibroblast Cell Shape in Three Dimensions.

PubMed

Brand, Christoph A; Linke, Marco; Weißenbruch, Kai; Richter, Benjamin; Bastmeyer, Martin; Schwarz, Ulrich S

2017-08-22

The shape of animal cells is an important regulator for many essential processes such as cell migration or division. It is strongly determined by the organization of the actin cytoskeleton, which is also the main regulator of cell forces. Quantitative analysis of cell shape helps to reveal the physical processes underlying cell shape and forces, but it is notoriously difficult to conduct it in three dimensions. Here we use direct laser writing to create 3D open scaffolds for adhesion of connective tissue cells through well-defined adhesion platforms. Due to actomyosin contractility in the cell contour, characteristic invaginations lined by actin bundles form between adjacent adhesion sites. Using quantitative image processing and mathematical modeling, we demonstrate that the resulting shapes are determined not only by contractility, but also by elastic stress in the peripheral actin bundles. In this way, cells can generate higher forces than through contractility alone. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

CD147-targeting siRNA inhibits cell-matrix adhesion of human malignant melanoma cells by phosphorylating focal adhesion kinase.

PubMed

Nishibaba, Rie; Higashi, Yuko; Su, Juan; Furukawa, Tatsuhiko; Kawai, Kazuhiro; Kanekura, Takuro

2012-01-01

CD147/basigin, highly expressed on the surface of malignant tumor cells including malignant melanoma (MM) cells, plays a critical role in the invasiveness and metastasis of MM. Metastasis is an orchestrated process comprised of multiple steps including adhesion and invasion. Integrin, a major adhesion molecule, co-localizes with CD147/basigin on the cell surface. Using the human MM cell line A375 that highly expresses CD147/basigin, we investigated whether CD147/basigin is involved in adhesion in association with integrin. CD147/basigin was knocked-down using siRNA targeting CD147 to elucidate the role of CD147/basigin. Cell adhesion was evaluated by adhesion assay on matrix-coated plates. The localization of integrin was inspected under a confocal microscope and the expression and phosphorylation of focal adhesion kinase (FAK), a downstream kinase of integrin, were examined by western blot analysis. Silencing of CD147/basigin in A375 cells by siRNA induced the phosphorylation of FAK at Y397. Integrin identified on the surface of parental cells was distributed in a speckled fashion in the cytoplasm of CD147 knockdown cells, resulting in morphological changes from a round to a polygonal shape with pseudopodial protrusions. Silencing of CD147/basigin in A375 cells clearly weakened their adhesiveness to collagen I and IV. Our results suggest that CD147/basigin regulates the adhesion of MM cells to extracellular matrices and of integrin β1 signaling via the phosphorylation of FAK. © 2011 Japanese Dermatological Association.

Tuning cell adhesion on polymeric and nanocomposite surfaces: Role of topography versus superhydrophobicity.

PubMed

Zangi, Sepideh; Hejazi, Iman; Seyfi, Javad; Hejazi, Ehsan; Khonakdar, Hossein Ali; Davachi, Seyed Mohammad

2016-06-01

Development of surface modification procedures which allow tuning the cell adhesion on the surface of biomaterials and devices is of great importance. In this study, the effects of different topographies and wettabilities on cell adhesion behavior of polymeric surfaces are investigated. To this end, an improved phase separation method was proposed to impart various wettabilities (hydrophobic and superhydrophobic) on polypropylene surfaces. Surface morphologies and compositions were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. Cell culture was conducted to evaluate the adhesion of 4T1 mouse mammary tumor cells. It was found that processing conditions such as drying temperature is highly influential in cell adhesion behavior due to the formation of an utterly different surface topography. It was concluded that surface topography plays a more significant role in cell adhesion behavior rather than superhydrophobicity since the nano-scale topography highly inhibited the cell adhesion as compared to the micro-scale topography. Such cell repellent behavior could be very useful in many biomedical devices such as those in drug delivery and blood contacting applications as well as biosensors. Copyright © 2016 Elsevier B.V. All rights reserved.

Morphological Observations of Mesenchymal Stem Cell Adhesion to a Nanoperiodic-Structured Titanium Surface Patterned Using Femtosecond Laser Processing

NASA Astrophysics Data System (ADS)

Oya, Kei; Aoki, Shun; Shimomura, Kazunori; Sugita, Norihiko; Suzuki, Kenji; Nakamura, Norimasa; Fujie, Hiromichi

2012-12-01

It is known that the adhesive and anisotropic properties of cell-derived biomaterials are affected by micro- or nanoscale structures processed on culture surfaces. In the present study, the femtosecond laser processing technique was used to scan a laser beam at an intensity of approximately the ablation threshold level on a titanium surface for nanoscale processing. Microscopy observation revealed that the processed titanium exhibited a periodic-patterned groove structure at the surface; the width and depth of the groove were 292 ±50 and 99 ±31 nm, respectively, and the periodic pitch of the groove was 501 ±100 nm. Human synovium-derived mesenchymal stem cells were cultured on the surface at a cell density of 3.0×103 cells/cm2 after 4 cell passages. For comparison, the cells were also cultured on a nonprocessed titanium surface under the condition identical to that of the processed surface. Results revealed that the duration for cell attachment to the surface was markedly reduced on the processed titanium as compared with the nonprocessed titanium. Moreover, on the processed titanium, cell extension area significantly increased while cell orientation was aligned along the direction of the periodic grooves. These results suggest that the femtosecond laser processing improves the adhesive and anisotropic properties of cells by producing the nanoperiodic structure on titanium culture surfaces.

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. Copyright © 2016 Elsevier Ltd. All rights reserved.

Penicillium purpurogenum cultures under ethanol-induced stress and its correlation with fungal adhesion and biodegrading ability.

PubMed

Gomaa, Ola M; Husseiny, Sherif M; Abd El Kareem, Hussein; Talaat, Riham

2016-10-01

Fungi are known to be affected by external environmental stimuli, resulting in different stress response effects, which in turn could be used to enhance its biodegrading ability. In a previous study, ethanol was used to manipulate cell-cell and cell-surface interaction to prevent cell loss and maximize the usage of Penicillium purpurogenum cells in the media, a correlation was drawn between ethanol oxidative stress, surface-bound proteins and fungal adhesion. The present study focuses on a more detailed study of the effect of ethanol on the same fungus. The results show that the presence of Yap1p gene and the detection of an oxidized form of glutathione (GSSG) suggest that a stress response might be involved in the adhesion process. The process of adhesion could be described as a signaling process and it is affected by the germ tube formation as an initial step in adhesion. Protein profile showed polymorphism in surface-bound proteins for cultures amended with ethanol when compared to control cultures. Ethanol also affected the DNA polymorphic profile of DNA, rendering the fungus genetically variable. P. purpurogenum produced phenol oxidase enzyme and could be used to degrade total phenols in olive mill waste water without the formation of biofilm on the surface of the containers.

Mena binds α5 integrin directly and modulates α5β1 function

PubMed Central

Riquelme, Daisy; Hughes-Alford, Shannon K.; Tadros, Jenny; Rudina, Shireen S.; O.Hynes, Richard; Lauffenburger, Douglas

2012-01-01

Mena is an Ena/VASP family actin regulator with roles in cell migration, chemotaxis, cell–cell adhesion, tumor cell invasion, and metastasis. Although enriched in focal adhesions, Mena has no established function within these structures. We find that Mena forms an adhesion-regulated complex with α5β1 integrin, a fibronectin receptor involved in cell adhesion, motility, fibronectin fibrillogenesis, signaling, and growth factor receptor trafficking. Mena bound directly to the carboxy-terminal portion of the α5 cytoplasmic tail via a 91-residue region containing 13 five-residue “LERER” repeats. In fibroblasts, the Mena–α5 complex was required for “outside-in” α5β1 functions, including normal phosphorylation of FAK and paxillin and formation of fibrillar adhesions. It also supported fibrillogenesis and cell spreading and controlled cell migration speed. Thus, fibroblasts require Mena for multiple α5β1-dependent processes involving bidirectional interactions between the extracellular matrix and cytoplasmic focal adhesion proteins. PMID:22908313

Nanofork for single cells adhesion measurement via ESEM-nanomanipulator system.

PubMed

Ahmad, Mohd Ridzuan; Nakajima, Masahiro; Kojima, Masaru; Kojima, Seiji; Homma, Michio; Fukuda, Toshio

2012-03-01

In this paper, single cells adhesion force was measured using a nanofork. The nanofork was used to pick up a single cell on a line array substrate inside an environmental scanning electron microscope (ESEM). The line array substrate was used to provide small gaps between the single cells and the substrate. Therefore, the nanofork could be inserted through these gaps in order to successfully pick up a single cell. Adhesion force was measured during the cell pick-up process from the deflection of the cantilever beam. The nanofork was fabricated using focused ion beam (FIB) etching process while the line array substrate was fabricated using nanoimprinting technology. As to investigate the effect of contact area on the strength of the adhesion force, two sizes of gap distance of line array substrate were used, i.e., 1 μm and 2 μm. Results showed that cells attached on the 1 μm gap line array substrate required more force to be released as compared to the cells attached on the 1 μm gap line array substrate.

Retinoids induce integrin-independent lymphocyte adhesion through RAR-α nuclear receptor activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whelan, Jarrett T.; Wang, Lei; Chen, Jianming

2014-11-28

Highlights: • Transcription and translation are required for retinoid-induced lymphocyte adhesion. • RAR activation is sufficient to induced lymphocyte cell adhesion. • Vitamin D derivatives inhibit RAR-prompted lymphocyte adhesion. • Adhesion occurs through a novel binding site within ADAM disintegrin domains. • RARα is a key nuclear receptor for retinoid-dependent lymphocyte cell adhesion. - Abstract: Oxidative metabolites of vitamin A, in particular all-trans-retinoic acid (atRA), have emerged as key factors in immunity by specifying the localization of immune cells to the gut. Although it is appreciated that isomers of retinoic acid activate the retinoic acid receptor (RAR) and retinoid Xmore » receptor (RXR) family of nuclear receptors to elicit cellular changes, the molecular details of retinoic acid action remain poorly defined in immune processes. Here we employ a battery of agonists and antagonists to delineate the specific nuclear receptors utilized by retinoids to evoke lymphocyte cell adhesion to ADAM (adisintegrin and metalloprotease) protein family members. We report that RAR agonism is sufficient to promote immune cell adhesion in both immortal and primary immune cells. Interestingly, adhesion occurs independent of integrin function, and mutant studies demonstrate that atRA-induced adhesion to ADAM members required a distinct binding interface(s) as compared to integrin recognition. Anti-inflammatory corticosteroids as well as 1,25-(OH){sub 2}D{sub 3}, a vitamin D metabolite that prompts immune cell trafficking to the skin, potently inhibited the observed adhesion. Finally, our data establish that induced adhesion was specifically attributable to the RAR-α receptor isotype. The current study provides novel molecular resolution as to which nuclear receptors transduce retinoid exposure into immune cell adhesion.« less

p38 Signaling and Receptor Recycling Events in a Microfluidic Endothelial Cell Adhesion Assay

PubMed Central

Vickers, Dwayne A. L.; Chory, Emma J.; Harless, Megan C.; Murthy, Shashi K.

2013-01-01

Adhesion-based microfluidic cell separation has proven to be very useful in applications ranging from cancer diagnostics to tissue engineering. This process involves functionalizing microchannel surfaces with a capture molecule. High specificity and purity capture can be achieved using this method. Despite these advances, little is known about the mechanisms that govern cell capture within these devices and their relationships to basic process parameters such as fluid shear stress and the presence of soluble factors. This work examines how the adhesion of human endothelial cells (ECs) is influenced by a soluble tetrapeptide, Arg-Glu-Asp-Val (REDV) and fluidic shear stress. The ability of these ECs to bind within microchannels coated with REDV is shown to be governed by shear- and soluble-factor mediated changes in p38 mitogen-activated protein kinase expression together with recycling of adhesion receptors from the endosome. PMID:23762436

Numerically bridging lamellipodial and filopodial activity during cell spreading reveals a potentially novel trigger of focal adhesion maturation.

PubMed

Loosli, Y; Vianay, B; Luginbuehl, R; Snedeker, J G

2012-05-01

We present a novel approach to modeling cell spreading, and use it to reveal a potentially central mechanism regulating focal adhesion maturation in various cell phenotypes. Actin bundles that span neighboring focal complexes at the lamellipodium-lamellum interface were assumed to be loaded by intracellular forces in proportion to bundle length. We hypothesized that the length of an actin bundle (with the corresponding accumulated force at its adhesions) may thus regulate adhesion maturation to ensure cell mechanical stability and morphological integrity. We developed a model to test this hypothesis, implementing a "top-down" approach to simplify certain cellular processes while explicitly incorporating complexity of other key subcellular mechanisms. Filopodial and lamellipodial activities were treated as modular processes with functional spatiotemporal interactions coordinated by rules regarding focal adhesion turnover and actin bundle dynamics. This theoretical framework was able to robustly predict temporal evolution of cell area and cytoskeletal organization as reported from a wide range of cell spreading experiments using micropatterned substrates. We conclude that a geometric/temporal modeling framework can capture the key functional aspects of the rapid spreading phase and resultant cytoskeletal complexity. Hence the model is used to reveal mechanistic insight into basic cell behavior essential for spreading. It demonstrates that actin bundles spanning nascent focal adhesions such that they are aligned to the leading edge may accumulate centripetal endogenous forces along their length, and could thus trigger focal adhesion maturation in a force-length dependent fashion. We suggest that this mechanism could be a central "integrating" factor that effectively coordinates force-mediated adhesion maturation at the lamellipodium-lamellum interface.

Continuum-level modelling of cellular adhesion and matrix production in aggregates.

PubMed

Geris, Liesbet; Ashbourn, Joanna M A; Clarke, Tim

2011-05-01

Key regulators in tissue-engineering processes such as cell culture and cellular organisation are the cell-cell and cell-matrix interactions. As mathematical models are increasingly applied to investigate biological phenomena in the biomedical field, it is important, for some applications, that these models incorporate an adequate description of cell adhesion. This study describes the development of a continuum model that represents a cell-in-gel culture system used in bone-tissue engineering, namely that of a cell aggregate embedded in a hydrogel. Cell adhesion is modelled through the use of non-local (integral) terms in the partial differential equations. The simulation results demonstrate that the effects of cell-cell and cell-matrix adhesion are particularly important for the survival and growth of the cell population and the production of extracellular matrix by the cells, concurring with experimental observations in the literature.

Neural cell adhesion molecule-deficient beta-cell tumorigenesis results in diminished extracellular matrix molecule expression and tumour cell-matrix adhesion.

PubMed

Håkansson, Joakim; Xian, Xiaojie; He, Liqun; Ståhlberg, Anders; Nelander, Sven; Samuelsson, Tore; Kubista, Mikael; Semb, Henrik

2005-01-01

To understand by which mechanism neural cell adhesion molecule (N-CAM) limits beta tumour cell disaggregation and dissemination, we searched for potential downstream genes of N-CAM during beta tumour cell progression by gene expression profiling. Here, we show that N-CAM-deficient beta-cell tumorigenesis is associated with changes in the expression of genes involved in cell-matrix adhesion and cytoskeletal dynamics, biological processes known to affect the invasive and metastatic behaviour of tumour cells. The extracellular matrix (ECM) molecules emerged as the primary target, i.e. N-CAM deficiency resulted in down-regulated mRNA expression of a broad range of ECM molecules. Consistent with this result, deficient deposition of major ECM stromal components, such as fibronectin, laminin 1 and collagen IV, was observed. Moreover, N-CAM-deficient tumour cells displayed defective matrix adhesion. These results offer a potential mechanism for tumour cell disaggregation during N-CAM-deficient beta tumour cell progression. Prospective consequences of these findings for the role of N-CAM in beta tumour cell dissemination are discussed.

Exploring the Limits of Cell Adhesion under Shear Stress within Physiological Conditions and beyond on a Chip.

PubMed

Stamp, Melanie E M; Jötten, Anna M; Kudella, Patrick W; Breyer, Dominik; Strobl, Florian G; Geislinger, Thomas M; Wixforth, Achim; Westerhausen, Christoph

2016-10-21

Cell adhesion processes are of ubiquitous importance for biomedical applications such as optimization of implant materials. Here, not only physiological conditions such as temperature or pH, but also topographical structures play crucial roles, as inflammatory reactions after surgery can diminish osseointegration. In this study, we systematically investigate cell adhesion under static, dynamic and physiologically relevant conditions employing a lab-on-a-chip system. We screen adhesion of the bone osteosarcoma cell line SaOs-2 on a titanium implant material for pH and temperature values in the physiological range and beyond, to explore the limits of cell adhesion, e.g., for feverish and acidic conditions. A detailed study of different surface roughness R q gives insight into the correlation between the cells' abilities to adhere and withstand shear flow and the topography of the substrates, finding a local optimum at R q = 22 nm. We use shear stress induced by acoustic streaming to determine a measure for the ability of cell adhesion under an external force for various conditions. We find an optimum of cell adhesion for T = 37 °C and pH = 7.4 with decreasing cell adhesion outside the physiological range, especially for high T and low pH. We find constant detachment rates in the physiological regime, but this behavior tends to collapse at the limits of 41 °C and pH 4.

Surgery-derived reactive oxygen species produced by polymorphonuclear leukocytes promote tumor recurrence: studies in an in vitro model.

PubMed

van Grevenstein, Wilhelmina M U; Aalbers, Arend G J; Ten Raa, Sander; Sluiter, Wim; Hofland, Leo J; Jeekel, Hans; van Eijck, Casper H J

2007-06-01

Tissue injury induces the acute phase response, aimed at minimizing damage and starting the healing process. Polymorphonuclear leukocytes (PMNs) respond to the presence of specific chemoattractants and begin to appear in large numbers. The aim of this study was to investigate the influence of reactive oxygen species (ROS) produced by PMNs on the interaction between colon carcinoma cells and mesothelial cells. An experimental human in vitro model was designed using Caco-2 colon carcinoma cells and primary cultures of mesothelial cells. Tumor cell adhesion to a mesothelial monolayer was assessed after preincubation of the mesothelium with stimulated PMNs and unstimulated PMNs. Mesothelial cells were also incubated with xanthine/xanthine oxidase (X/XO) complex producing ROS after which adhesion of Caco-2 cells was investigated and the expression of adhesion molecules (ICAM-1, VCAM-1, and CD44) by means of enzyme immunoassay. In the control situation the average adhesion of Caco-2 cells to the mesothelial monolayers was 23%. Mesothelial monolayers incubated with unstimulated PMNs showed a 25% increase of tumor cell adhesion (P < 0.05). The adhesion of tumor to the monolayers incubated with the N-formyl-methionyl-leucyl-phenylalanine-stimulated PMNs increased with 40% (P < 0.01). Incubation of the mesothelium with X/XO resulted in an enhancement of adhesion of Caco-2 cells of 70% and an up-regulation of expression of ICAM-1, VCAM-1, and CD44. This study reveals an increase of tumor cell adhesion to the mesothelium induced by incubating the mesothelial monolayers with PMNs. PMNs are producing a number of products, like proteolytic enzymes, cytokines, and ROS. These factors up-regulate the expression of adhesion molecules and in that way stimulate the adhesion of tumor to the mesothelium.

The evaluation of p,p'-DDT exposure on cell adhesion of hepatocellular carcinoma.

PubMed

Jin, Xiaoting; Chen, Meilan; Song, Li; Li, Hanqing; Li, Zhuoyu

2014-08-01

Many studies have found a positive association between the progression of hepatocellular carcinoma and DDT exposure. These studies mainly focus on the effect of DDT exposure on cell proliferation and epithelial to mesenchymal transition (EMT) promotion. However, the influence of DDT on cell adhesion of hepatocellular carcinoma remains to be unclear. The aim of our study was to determine the effect of p,p'-DDT on cell adhesion of hepatocellular carcinoma in vitro and in vivo. The data showed that p,p'-DDT, exposing HepG2 cells for 6 days, decreased cell-cell adhesion and elevated cell-matrix adhesion. Strikingly, p,p'-DDT increased reactive oxygen species (ROS) content, and this was accompanied by the activation of JAK/STAT3 pathway. Moreover, ROS inhibitor supplement reversed these effects significantly. However, the addition of ER inhibitor, ICI, had no effect on the p,p'-DDT-induced effects. p,p'-DDT altered the mRNA levels of related adhesion molecules, including inhibition of E-cadherin and promotion of N-cadherin along with CD29. Interestingly, the p,p'-DDT-altered adhesion molecules could be reversed with JAK inhibitor or STAT3 inhibitor. Likewise, p,p'-DDT stimulated the JAK/STAT3 pathway in nude mice, as well as altered the mRNA levels of E-cadherin, N-cadherin, and CD29. Taken together, these results indicate that p,p'-DDT profoundly promotes the adhesion process by decreasing cell-cell adhesion and inducing cell-matrix adhesion via the ROS-mediated JAK/STAT3 pathway. All these events account for the carcinogenic potential of p,p'-DDT in liver. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Correlation between surface carbon concentration and adhesive strength at the Si cell/EVA interface in a PV module

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dhere, N.G.; Wollam, M.E.; Gadre, K.S.

1997-12-31

Silicon solar cell/EVA composite is being studied with an objective to further improve the manufacturing technology of PV modules. Sample extraction and adhesion strength measurement process has been modified. Silicon and EVA samples were extracted from solar cells of new and field-deployed modules. Optical microscopy, SEM, and AES of samples from new modules revealed EVA islands covering most of the silicon cell surface indicating a cohesive failure. A good correlation was observed between the adhesive strength and surface concentration of carbon. A low carbon concentration which indicated less EVA clinging to cell surface always resulted in low adhesive strengths. Themore » correlation provides a simple technique for inferring properties of EVA.« less

MiR-126 and miR-126* regulate shear-resistant firm leukocyte adhesion to human brain endothelium

PubMed Central

Cerutti, Camilla; Edwards, Laura J.; de Vries, Helga E.; Sharrack, Basil; Male, David K.; Romero, Ignacio A.

2017-01-01

Leukocyte adhesion to brain endothelial cells, the blood-brain barrier main component, is a critical step in the pathogenesis of neuroinflammatory diseases such as multiple sclerosis (MS). Leukocyte adhesion is mediated mainly by selectins, cell adhesion molecules and chemokines induced by pro-inflammatory cytokines such as TNFα and IFNγ, but the regulation of this process is not fully clear. This study investigated the regulation of firm leukocyte adhesion to human brain endothelium by two different brain endothelial microRNAs (miRs), miR-126 and miR-126*, that are downregulated by TNFα and IFNγ in a human brain endothelial cell line, hCMEC/D3. Using a leukocyte adhesion in vitro assay under shear forces mimicking blood flow, we observed that reduction of endothelial miR-126 and miR-126* enhanced firm monocyte and T cell adhesion to hCMEC/D3 cells, whereas their increased expression partially prevented THP1, Jurkat and primary MS patient-derived PBMC firm adhesion. Furthermore, we observed that miR-126* and miR-126 downregulation increased E-selectin and VCAM1, respectively, while miR-126 overexpression reduced VCAM1 and CCL2 expression by hCMEC/D3 cells, suggesting that these miRs regulate leukocyte adhesion by modulating the expression of adhesion-associated endothelial mRNA targets. Hence, human brain endothelial miR-126 and miR-126* could be used as a therapeutic tool to reduce leukocyte adhesion and thus reduce neuroinflammation. PMID:28358058

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Premnath, Priyatha, E-mail: priyatha.premnath@ryerson.ca; Tavangar, Amirhossein, E-mail: atavanga@ryerson.ca; Tan, Bo, E-mail: tanbo@ryerson.ca

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 approachmore » 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 cancer cells while favoring the adhesion of normal cells. - Highlights: • Si platforms with cytophobic/philic patterns were developed to program cell growth. • Both nanotopography and chemistry contributed to the cytophobic property. • Cytophobic zones efficiently repel and drive HeLa cells to migrate to adhesive sites. • The approach enables cell patterning, directionality, channelling, and trapping. • This approach paves the way for developing anti-cancer platforms.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kornu, R.; Kelly, M.A.; Smith, R.L.

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%more » (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.« less

ILK mediates LPS-induced vascular adhesion receptor expression and subsequent leucocyte trans-endothelial migration.

PubMed

Hortelano, Sonsoles; López-Fontal, Raquel; Través, Paqui G; Villa, Natividad; Grashoff, Carsten; Boscá, Lisardo; Luque, Alfonso

2010-05-01

The inflammatory response to injurious agents is tightly regulated to avoid adverse consequences of inappropriate leucocyte accumulation or failed resolution. Lipopolysaccharide (LPS)-activated endothelium recruits leucocytes to the inflamed tissue through controlled expression of membrane-associated adhesion molecules. LPS responses in macrophages are known to be regulated by integrin-linked kinase (ILK); in this study, we investigated the role of ILK in the regulation of the LPS-elicited inflammatory response in endothelium. This study was performed on immortalized mouse endothelial cells (EC) isolated from lung and coronary vasculature. Cells were thoroughly characterized and the role of ILK in the regulation of the LPS response was investigated by suppressing ILK expression using siRNA and shRNA technologies. Phenotypic and functional analyses confirmed that the immortalized cells behaved as true EC. LPS induced the expression of the inflammatory genes E-selectin, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). ILK knockdown impaired LPS-mediated endothelial activation by preventing the induction of ICAM-1 and VCAM-1. Blockade of the LPS-induced response inhibited the inflammatory-related processes of firm adhesion and trans-endothelial migration of leucocytes. ILK is involved in the expression of cell adhesion molecules by EC activated with the inflammatory stimulus LPS. This reduced expression modulates leucocyte adhesion to the endothelium and the extravasation process. This finding suggests ILK as a potential anti-inflammatory target for the development of vascular-specific treatments for inflammation-related diseases.

Le(x) glycan mediates homotypic adhesion of embryonal cells independently from E-cadherin: a preliminary note.

PubMed

Handa, Kazuko; Takatani-Nakase, Tomoka; Larue, Lionel; Stemmler, Marc P; Kemler, Rolf; Hakomori, Sen-itiroh

2007-06-22

Le(x) glycan and E-cadherin (Ecad) are co-expressed at embryonal stem (ES) cells and embryonal carcinoma (EC) cells. While the structure and function of Ecad mediating homotypic adhesion of these cells have been well established, evidence that Le(x) glycan also mediates such adhesion is weak, despite the fact that Le(x) oligosaccharide inhibits the compaction process. To provide stronger evidence, we knocked out Ecad gene in EC and ES cells to establish F9 Ecad (-/-) and D3M Ecad (-/-) cells, which highly express Le(x) glycan but do not express Ecad at all. Both F9 Ecad (-/-) and D3M Ecad (-/-) cells displayed strong autoaggregation in the presence of Ca(2+), while PYS-2 cells, which express trace amount of Ecad and undetectable level of Le(x) glycan, did not display autoaggregation. In addition, F9 Ecad (-/-) and D3M Ecad (-/-) cells displayed strong adhesion to plates coated with Le(x) glycosphingolipid (III(3)FucnLc4Cer), in dose-dependent manner, in the presence of Ca(2+). Thus, ES or EC cells display autoaggregation and strong adhesion to Le(x)-coated plates in the absence of Ecad, further supporting the notion of Le(x) self-recognition (i.e., Le(x)-to-Le(x) interaction) in cell adhesion.

Desmoglein 3 regulates membrane trafficking of cadherins, an implication in cell-cell adhesion.

PubMed

Moftah, Hanan; Dias, Kasuni; Apu, Ehsanul Hoque; Liu, Li; Uttagomol, Jutamas; Bergmeier, Lesley; Kermorgant, Stephanie; Wan, Hong

2017-05-04

E-cadherin mediated cell-cell adhesion plays a critical role in epithelial cell polarization and morphogenesis. Our recent studies suggest that the desmosomal cadherin, desmoglein 3 (Dsg3) cross talks with E-cadherin and regulates its adhesive function in differentiating keratinocytes. However, the underlying mechanism remains not fully elucidated. Since E-cadherin trafficking has been recognized to be a central determinant in cell-cell adhesion and homeostasis we hypothesize that Dsg3 may play a role in regulating E-cadherin trafficking and hence the cell-cell adhesion. Here we investigated this hypothesis in cells with loss of Dsg3 function through RNAi mediated Dsg3 knockdown or the stable expression of the truncated mutant Dsg3ΔC. Our results showed that loss of Dsg3 resulted in compromised cell-cell adhesion and reduction of adherens junction and desmosome protein expression as well as the cortical F-actin formation. As a consequence, cells failed to polarize but instead displayed aberrant cell flattening. Furthermore, retardation of E-cadherin internalization and recycling was consistently observed in these cells during the process of calcium induced junction assembling. In contrast, enhanced cadherin endocytosis was detected in cells with overexpression of Dsg3 compared to control cells. Importantly, this altered cadherin trafficking was found to be coincided with the reduced expression and activity of Rab proteins, including Rab5, Rab7 and Rab11 which are known to be involved in E-cadherin trafficking. Taken together, our findings suggest that Dsg3 functions as a key in cell-cell adhesion through at least a mechanism of regulating E-cadherin membrane trafficking.

Differential Expression of Adhesion-Related Proteins and MAPK Pathways Lead to Suitable Osteoblast Differentiation of Human Mesenchymal Stem Cells Subpopulations.

PubMed

Leyva-Leyva, Margarita; López-Díaz, Annia; Barrera, Lourdes; Camacho-Morales, Alberto; Hernandez-Aguilar, Felipe; Carrillo-Casas, Erika M; Arriaga-Pizano, Lourdes; Calderón-Pérez, Jaime; García-Álvarez, Jorge; Orozco-Hoyuela, Gabriel; Piña-Barba, Cristina; Rojas-Martínez, Augusto; Romero-Díaz, Víktor; Lara-Arias, Jorge; Rivera-Bolaños, Nancy; López-Camarillo, César; Moncada-Saucedo, Nidia; Galván-De los Santos, Alejandra; Meza-Urzúa, Fátima; Villarreal-Gómez, Luis; Fuentes-Mera, Lizeth

2015-11-01

Cellular adhesion enables communication between cells and their environment. Adhesion can be achieved throughout focal adhesions and its components influence osteoblast differentiation of human mesenchymal stem cells (hMSCs). Because cell adhesion and osteoblast differentiation are closely related, this article aimed to analyze the expression profiles of adhesion-related proteins during osteoblastic differentiation of two hMSCs subpopulations (CD105(+) and CD105(-)) and propose a strategy for assembling bone grafts based on its adhesion ability. In vitro experiments of osteogenic differentiation in CD105(-) cells showed superior adhesion efficiency and 2-fold increase of α-actinin expression compared with CD105(+) cells at the maturation stage. Interestingly, levels of activated β1-integrin increased in CD105(-) cells during the process. Additionally, the CD105(-) subpopulation showed 3-fold increase of phosphorylated FAK(Y397) compared to CD105(+) cells. Results also indicate that ERK1/2 was activated during CD105(-) bone differentiation and participation of mitogen-activated protein kinase (MAPK)-p38 in CD105(+) differentiation through a focal adhesion kinase (FAK)-independent pathway. In vivo trial demonstrated that grafts containing CD105(-) showed osteocytes embedded in a mineralized matrix, promoted adequate graft integration, increased host vascular infiltration, and efficient intramembranous repairing. In contrast, grafts containing CD105(+) showed deficient endochondral ossification and fibrocartilaginous tissue. Based on the expression of α-actinin, FAKy,(397) and ERK1/2 activation, we define maturation stage as critical for bone graft assembling. By in vitro assays, CD105(-) subpopulation showed superior adhesion efficiency compared to CD105(+) cells. Considering in vitro and in vivo assays, this study suggests that integration of a scaffold with CD105(-) subpopulation at the maturation stage represents an attractive strategy for clinical use in orthopedic bioengineering.

Wavelet Imaging on Multiple Scales (WIMS) reveals focal adhesion distributions, dynamics and coupling between actomyosin bundle stability

PubMed Central

Toplak, Tim; Palmieri, Benoit; Juanes-García, Alba; Vicente-Manzanares, Miguel; Grant, Martin; Wiseman, Paul W.

2017-01-01

We introduce and use Wavelet Imaging on Multiple Scales (WIMS) as an improvement to fluorescence correlation spectroscopy to measure physical processes and features that occur across multiple length scales. In this study, wavelet transforms of cell images are used to characterize molecular dynamics at the cellular and subcellular levels (i.e. focal adhesions). We show the usefulness of the technique by applying WIMS to an image time series of a migrating osteosarcoma cell expressing fluorescently labelled adhesion proteins, which allows us to characterize different components of the cell ranging from optical resolution scale through to focal adhesion and whole cell size scales. Using WIMS we measured focal adhesion numbers, orientation and cell boundary velocities for retraction and protrusion. We also determine the internal dynamics of individual focal adhesions undergoing assembly, disassembly or elongation. Thus confirming as previously shown, WIMS reveals that the number of adhesions and the area of the protruding region of the cell are strongly correlated, establishing a correlation between protrusion size and adhesion dynamics. We also apply this technique to characterize the behavior of adhesions, actin and myosin in Chinese hamster ovary cells expressing a mutant form of myosin IIB (1935D) that displays decreased filament stability and impairs front-back cell polarity. We find separate populations of actin and myosin at each adhesion pole for both the mutant and wild type form. However, we find these populations move rapidly inwards toward one another in the mutant case in contrast to the cells that express wild type myosin IIB where those populations remain stationary. Results obtained with these two systems demonstrate how WIMS has the potential to reveal novel correlations between chosen parameters that belong to different scales. PMID:29049414

Activation of GPR4 by Acidosis Increases Endothelial Cell Adhesion through the cAMP/Epac Pathway

PubMed Central

Leffler, Nancy R.; Asch, Adam S.; Witte, Owen N.; Yang, Li V.

2011-01-01

Endothelium-leukocyte interaction is critical for inflammatory responses. Whereas the tissue microenvironments are often acidic at inflammatory sites, the mechanisms by which cells respond to acidosis are not well understood. Using molecular, cellular and biochemical approaches, we demonstrate that activation of GPR4, a proton-sensing G protein-coupled receptor, by isocapnic acidosis increases the adhesiveness of human umbilical vein endothelial cells (HUVECs) that express GPR4 endogenously. Acidosis in combination with GPR4 overexpression further augments HUVEC adhesion with U937 monocytes. In contrast, overexpression of a G protein signaling-defective DRY motif mutant (R115A) of GPR4 does not elicit any increase of HUVEC adhesion, indicating the requirement of G protein signaling. Downregulation of GPR4 expression by RNA interference reduces the acidosis-induced HUVEC adhesion. To delineate downstream pathways, we show that inhibition of adenylate cyclase by inhibitors, 2′,5′-dideoxyadenosine (DDA) or SQ 22536, attenuates acidosis/GPR4-induced HUVEC adhesion. Consistently, treatment with a cAMP analog or a Gi signaling inhibitor increases HUVEC adhesiveness, suggesting a role of the Gs/cAMP signaling in this process. We further show that the cAMP downstream effector Epac is important for acidosis/GPR4-induced cell adhesion. Moreover, activation of GPR4 by acidosis increases the expression of vascular adhesion molecules E-selectin, VCAM-1 and ICAM-1, which are functionally involved in acidosis/GPR4-mediated HUVEC adhesion. Similarly, hypercapnic acidosis can also activate GPR4 to stimulate HUVEC adhesion molecule expression and adhesiveness. These results suggest that acidosis/GPR4 signaling regulates endothelial cell adhesion mainly through the Gs/cAMP/Epac pathway and may play a role in the inflammatory response of vascular endothelial cells. PMID:22110680

Epithelial cell morphology and adhesion on diamond films deposited and chemically modified by plasma processes.

PubMed

Rezek, Bohuslav; Ukraintsev, Egor; Krátká, Marie; Taylor, Andrew; Fendrych, Frantisek; Mandys, Vaclav

2014-09-01

The authors show that nanocrystalline diamond (NCD) thin films prepared by microwave plasma enhanced chemical vapor deposition apparatus with a linear antenna delivery system are well compatible with epithelial cells (5637 human bladder carcinoma) and significantly improve the cell adhesion compared to reference glass substrates. This is attributed to better adhesion of adsorbed layers to diamond as observed by atomic force microscopy (AFM) beneath the cells. Moreover, the cell morphology can be adjusted by appropriate surface treatment of diamond by using hydrogen and oxygen plasma. Cell bodies, cytoplasmic rims, and filopodia were characterized by Peakforce AFM. Oxidized NCD films perform better than other substrates under all conditions (96% of cells adhered well). A thin adsorbed layer formed from culture medium and supplemented with fetal bovine serum (FBS) covered the diamond surface and played an important role in the cell adhesion. Nevertheless, 50-100 nm large aggregates formed from the RPMI medium without FBS facilitated cell adhesion also on hydrophobic hydrogenated NCD (increase from 23% to 61%). The authors discuss applicability for biomedical uses.

Drug-induced in vitro inhibition of neutrophil-endothelial cell adhesion.

PubMed Central

Pellegatta, F.; Lu, Y.; Radaelli, A.; Zocchi, M. R.; Ferrero, E.; Chierchia, S.; Gaja, G.; Ferrero, M. E.

1996-01-01

1. Leukocyte-endothelial cell interactions play an important role during ischaemia-reperfusion events. Adhesion molecules are specifically implicated in this interaction process. 2. Since defibrotide has been shown to be an efficient drug in reducing damage due to ischaemia-reperfusion in many experimental models, we analysed the effect of defibrotide in vitro on leukocyte adhesion to endothelial cells in basal conditions and after their stimulation. 3. In basal conditions, defibrotide (1000 micrograms ml-1) partially inhibited leukocyte adhesion to endothelial cells by 17.3% +/- 3.6 (P < 0.05), and after endothelial cell stimulation (TNF-alpha, 500 u ml-1) or after leukocyte stimulation (fMLP, 10(-7) M), it inhibited leukocyte adhesion by 26.5% +/- 3.4 and 32.4% +/- 1.8, respectively (P < 0.05). 4. In adhesion blockage experiments, the use of the monoclonal antibody anti-CD31 (5 micrograms ml-1) did not demonstrate a significant inhibitory effect whereas use of the monoclonal antibody anti-LFA-1 (5 micrograms ml-1) significantly interfered with the effect of defibrotide. 5. This result was confirmed in NIH/3T3-ICAM-1 transfected cells. 6. We conclude that defibrotide is able to interfere with leukocyte adhesion to endothelial cells mainly in activated conditions and that the ICAM-1/LFA-1 adhesion system is involved in the defibrotide mechanism of action. PMID:8762067

Filling in the Gap in Galectin-1 Export

DTIC Science & Technology

2007-09-01

Distribution Unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT No abstract was provided. 15. SUBJECT TERMS Galectin-1, yeast two hybrid...cell-cell adhesion, cell-extracellular matrix adhesion, and metastasis. Studies indicate that galectins have important roles in cancer as these...Since galectins are important molecules involved in the above-mentioned oncogenic processes, we proposed to identify the molecular mechanisms involved

Active properties of living tissues lead to size-dependent dewetting

NASA Astrophysics Data System (ADS)

Perez-Gonzalez, Carlos; Alert, Ricard; Blanch-Mercader, Carles; Gomez-Gonzalez, Manuel; Casademunt, Jaume; Trepat, Xavier

Key biological processes such as cancer and development are characterized by drastic transitions from 2D to a 3D geometry. These rearrangements have been classically studied as a wetting problem. According to this theory, wettability of a substrate by an epithelium is determined by the competition between cell-cell and cell-substrate adhesion energies. In contrast, we found that, far from a passive process, tissue dewetting is an active process driven by tissue internal forces. Experimentally, we reproduced epithelial dewetting by promoting a progressive formation of intercellular junctions in a monolayer of epithelial cells. Interestingly, the formation of intercellular junctions produces an increase in cell contractility, with the subsequent increase in traction and intercellular stress. At a certain time, tissue tension overcomes cell-substrate maximum adhesion and the monolayer spontaneously dewets the substrate. We developed an active polar fluid model, finding both theoretically and experimentally that critical contractility to promote wetting-dewetting transition depends on cell-substrate adhesion and, unexpectedly, on tissue size. As a whole, this work generalizes wetting theory to living tissues, unveiling unprecedented properties due to their unique active nature.

DDB2 (damaged-DNA binding 2) protein: a new modulator of nanomechanical properties and cell adhesion of breast cancer cells

NASA Astrophysics Data System (ADS)

Barbieux, Claire; Bacharouche, Jalal; Soussen, Charles; Hupont, Sébastien; Razafitianamaharavo, Angélina; Klotz, Rémi; Pannequin, Rémi; Brie, David; Bécuwe, Philippe; Francius, Grégory; Grandemange, Stéphanie

2016-02-01

DDB2, known for its role in DNA repair, was recently shown to reduce mammary tumor invasiveness by inducing the transcription of IκBα, an inhibitor of NF-κB activity. Since cellular adhesion is a key event during the epithelial to mesenchymal transition (EMT) leading to the invasive capacities of breast tumor cells, the aim of this study was to investigate the role of DDB2 in this process. Thus, using low and high DDB2-expressing MDA-MB231 and MCF7 cells, respectively, in which DDB2 expression was modulated experimentally, we showed that DDB2 overexpression was associated with a decrease of adhesion abilities on glass and plastic areas of breast cancer cells. Then, we investigated cell nanomechanical properties by atomic force microscopy (AFM). Our results revealed significant changes in the Young's Modulus value and the adhesion force in MDA-MB231 and MCF7 cells, whether DDB2 was expressed or not. The cell stiffness decrease observed in MDA-MB231 and MCF7 expressing DDB2 was correlated with a loss of the cortical actin-cytoskeleton staining. To understand how DDB2 regulates these processes, an adhesion-related gene PCR-Array was performed. Several adhesion-related genes were differentially expressed according to DDB2 expression, indicating that important changes are occurring at the molecular level. Thus, this work demonstrates that AFM technology is an important tool to follow cellular changes during tumorigenesis. Moreover, our data revealed that DDB2 is involved in early events occurring during metastatic progression of breast cancer cells and will contribute to define this protein as a new marker of metastatic progression in this type of cancer.

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 strongly fibrinogen adherent cells appearing in macrophages and highly represented in dendritic cells, but not observed in monocytes.

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-population of strongly fibrinogen adherent cells appearing in macrophages and highly represented in dendritic cells, but not observed in monocytes. PMID:25343359

Marine Bacterial Polysaccharide EPS11 Inhibits Cancer Cell Growth via Blocking Cell Adhesion and Stimulating Anoikis

PubMed Central

Cao, Ruobing; Jin, Weihua; Shan, Yeqi; Wang, Ju; Liu, Ge; Kuang, Shan

2018-01-01

Tumor cells that acquire metastatic potential have developed resistance to anoikis, a cell death process, after detachment from their primary site to the second organ. In this study, we investigated the molecular mechanisms of a novel marine bacterial polysaccharide EPS11 which exerts its cytotoxic effects through affecting cancer cell adhesion and anoikis. Firstly, we found that EPS11 could significantly affect cell proliferation and block cell adhesion in A549 cells. We further demonstrated that the expression of several cell adhesion associated proteins is downregulated and the filiform structures of cancer cells are destroyed after EPS11 treatment. Interestingly, the destruction of filiform structures in A549 cells by EPS11 is in a dose-dependent manner, and the inhibitory tendency is very consistent with that observed in the cell adhesion assay, which confirms that filiform structures play important roles in modulating cell adhesion. Moreover, we showed that EPS11 induces apoptosis of A549 cells through stimulating βIII-tubulin associated anoikis: (i) EPS11 inhibits the expression of βIII-tubulin in both transcription and translation levels; and (ii) EPS11 treatment dramatically decreases the phosphorylation of protein kinase B (PKB or AKT), a critical downstream effector of βIII-tubulin. Importantly, EPS11 evidently inhibits the growth of A549-derived tumor xenografts in vivo. Thus, our results suggest that EPS11 may be a potential candidate for human non-small cell lung carcinoma treatment via blocking filiform structure mediated adhesion and stimulating βIII-tubulin associated anoikis. PMID:29518055

Loss of the endothelial glycocalyx is associated with increased E-selectin mediated adhesion of lung tumour cells to the brain microvascular endothelium.

PubMed

Rai, Srijana; Nejadhamzeeigilani, Zaynab; Gutowski, Nicholas J; Whatmore, Jacqueline L

2015-09-25

Arrest of metastasising lung cancer cells to the brain microvasculature maybe mediated by interactions between ligands on circulating tumour cells and endothelial E-selectin adhesion molecules; a process likely to be regulated by the endothelial glycocalyx. Using human cerebral microvascular endothelial cells and non-small cell lung cancer (NSCLC) cell lines, we describe how factors secreted by NSCLC cells i.e. cystatin C, cathepsin L, insulin-like growth factor-binding protein 7 (IGFBP7), vascular endothelial growth factor (VEGF) and tumour necrosis factor-alpha (TNF-α), damage the glycocalyx and enhance initial contacts between lung tumour and cerebral endothelial cells. Endothelial cells were treated with tumour secreted-proteins or lung tumour conditioned medium (CM). Surface levels of E-selectin were quantified by ELISA. Adhesion of A549 and SK-MES-1 cells was examined under flow conditions (1 dyne/cm(2)). Alterations in the endothelial glycocalyx were quantified by binding of fluorescein isothiocyanate-linked wheat germ agglutinin (WGA-FITC). A549 and SK-MES-1 CM and secreted-proteins significantly enhanced endothelial surface E-selectin levels after 30 min and 4 h and tumour cell adhesion after 30 min, 4 and 24 h. Both coincided with significant glycocalyx degradation; A549 and SK-MES-1 CM removing 55 ± 12 % and 58 ± 18.7 % of WGA-FITC binding, respectively. Inhibition of E-selectin binding by monoclonal anti-E-selectin antibody completely attenuated tumour cell adhesion. These data suggest that metastasising lung cancer cells facilitate their own adhesion to the brain endothelium by secreting factors that damage the endothelial glycocalyx, resulting in exposure of the previously shielded adhesion molecules and engagement of the E-selectin-mediated adhesion axis.

FAK is required for tension-dependent organization of collective cell movements in Xenopus mesendoderm

PubMed Central

Bjerke, Maureen A.; Dzamba, Bette; Wang, Chong; DeSimone, Douglas W.

2014-01-01

Collective cell movements are integral to biological processes such as embryonic development and wound healing and also have a prominent role in some metastatic cancers. In migrating Xenopus mesendoderm, traction forces are generated by cells through integrin-based adhesions and tension transmitted across cadherin adhesions. This is accompanied by assembly of a mechanoresponsive cadherin adhesion complex containing keratin intermediate filaments and the catenin-family member plakoglobin. We demonstrate that focal adhesion kinase (FAK), a major component of integrin adhesion complexes, is required for normal morphogenesis at gastrulation, closure of the anterior neural tube, axial elongation and somitogenesis. Depletion of zygotically expressed FAK results in disruption of mesendoderm tissue polarity similar to that observed when expression of keratin or plakoglobin is inhibited. Both individual and collective migrations of mesendoderm cells from FAK depleted embryos are slowed, cell protrusions are disordered, and cell spreading and traction forces are decreased. Additionally, keratin filaments fail to organize at the rear of cells in the tissue and association of plakoglobin with cadherin is diminished. These findings suggest that FAK is required for the tension-dependent assembly of the cadherin adhesion complex that guides collective mesendoderm migration, perhaps by modulating the dynamic balance of substrate traction forces and cell cohesion needed to establish cell polarity. PMID:25127991

The consequence of biologic graft processing on blood interface biocompatibility and mechanics.

PubMed

Van de Walle, Aurore B; Uzarski, Joseph S; McFetridge, Peter S

2015-09-01

Processing ex vivo derived tissues to reduce immunogenicity is an effective approach to create biologically complex materials for vascular reconstruction. Due to the sensitivity of small diameter vascular grafts to occlusive events, the effect of graft processing on critical parameters for graft patency, such as peripheral cell adhesion and wall mechanics, requires detailed analysis. Isolated human umbilical vein sections were used as model allogenic vascular scaffolds that were processed with either: 1. sodium dodecyl sulfate (SDS), 2. ethanol/acetone (EtAc), or 3. glutaraldehyde (Glu). Changes in material mechanics were assessed via uniaxial tensile testing. Peripheral cell adhesion to the opaque grafting material was evaluated using an innovative flow chamber that allows direct observation of the blood-graft interface under physiological shear conditions. All treatments modified the grafts tensile strain and stiffness properties, with physiological modulus values decreasing from Glu 240±12 kPa to SDS 210±6 kPa and EtAc 140±3 kPa, P<.001. Relative to glutaraldehyde treatments, neutrophil adhesion to the decellularized grafts increased, with no statistical difference observed between SDS or EtAc treatments. Early platelet adhesion (% surface coverage) showed no statistical difference between the three treatments; however, quantification of platelet aggregates was significantly higher on SDS scaffolds compared to EtAc or Glu. Tissue processing strategies applied to the umbilical vein scaffold were shown to modify structural mechanics and cell adhesion properties, with the EtAc treatment reducing thrombotic events relative to SDS treated samples. This approach allows time and cost effective prescreening of clinically relevant grafting materials to assess initial cell reactivity.

Adhesion of Chlamydomonas microalgae to surfaces is switchable by light

NASA Astrophysics Data System (ADS)

Kreis, Christian Titus; Le Blay, Marine; Linne, Christine; Makowski, Marcin Michal; Bäumchen, Oliver

2018-01-01

Microalgae are photoactive microbes that live in liquid-infused environments, such as soil, temporary pools and rocks, where they encounter and colonize a plethora of surfaces. Their photoactivity manifests itself in a variety of processes, including light-directed motility (phototaxis), the growth of microalgal populations, and their photosynthetic machinery. Although microbial responses to light have been widely recognized, any influence of light on cell-surface interactions remains elusive. Here, we reveal that the unspecific adhesion of microalgae to surfaces can be reversibly switched on and off by light. Using a micropipette force spectroscopy technique, we measured in vivo single-cell adhesion forces and show that the microalga's flagella provide light-switchable adhesive contacts with the surface. This light-induced adhesion to surfaces is an active and completely reversible process that occurs on a timescale of seconds. Our results suggest that light-switchable adhesiveness is a natural functionality of microalgae to regulate the transition between the planktonic and the surface-associated state, which yields an adhesive adaptation to optimize the photosynthetic efficiency in conjunction with phototaxis.

Tunable swelling of polyelectrolyte multilayers in cell culture media for modulating NIH-3T3 cells adhesion.

PubMed

Qi, Wei; Cai, Peng; Yuan, Wenjing; Wang, Hua

2014-11-01

For polyelectrolyte multilayers (PEMs) assembled by the layer-by-layer (LbL) assembly technique, their nanostructure and properties can be governed by many parameters during the building process. Here, it was demonstrated that the swelling of the PEMs containing poly(diallyldimethylammonium chloride) (PDDA) and poly(sodium 4-styrenesulfonate) (PSS) in cell culture media could be tuned with changing supporting salt solutions during the assembly process. Importantly, the influence of the PEMs assembled in different salt solutions on NIH-3T3 cell adhesion was observable. Specifically, the cells could possess a higher affinity for the films assembled in low salt concentration (i.e. 0.15M NaCl) or no salt, the poorly swelling films in cell culture media, which was manifested by the large cell spreading area and focal adhesions. In contrast, those were assembled in higher salt concentration, highly swelling films in cell culture media, were less attractive for the fibroblasts. As a result, the cell adhesion behaviors may be manipulated by tailoring the physicochemical properties of the films, which could be performed by changing the assembly conditions such as supporting salt concentration. Such a finding might promise a great potential in designing desired biomaterials for tissue engineering and regenerative medicine. © 2014 Wiley Periodicals, Inc.

Silicon concentrator cell-assembly development

NASA Astrophysics Data System (ADS)

1982-08-01

The purpose was to develop an improved cell assembly design for photovoltaic concentrator receivers. Efforts were concentrated on a study of adhesive/separator systems that might be applied between cell and substrate, because this area holds the key to improved heat transfer, electrical isolation and adhesion. It is also the area in which simpler construction methods offer the greatest benefits for economy and reliability in the manufacturing process. Of the ten most promising designs subjected to rigorous environmental testing, eight designs featuring acrylic and silicon adhesives and fiberglass and polyester separators performed very well.

The mechanics of cellular compartmentalization as a model for tumor spreading

NASA Astrophysics Data System (ADS)

Fritsch, Anatol; Pawlizak, Steve; Zink, Mareike; Kaes, Josef A.

2012-02-01

Based on a recently developed surgical method of Michael H"ockel, which makes use of cellular confinement to compartments in the human body, we study the mechanics of the process of cell segregation. Compartmentalization is a fundamental process of cellular organization and occurs during embryonic development. A simple model system can demonstrate the process of compartmentalization: When two populations of suspended cells are mixed, this mixture will eventually segregate into two phases, whereas mixtures of the same cell type will not. In the 1960s, Malcolm S. Steinberg formulated the so-called differential adhesion hypothesis which explains the segregation in the model system and the process of compartmentalization by differences in surface tension and adhesiveness of the interacting cells. We are interested in to which extend the same physical principles affect tumor growth and spreading between compartments. For our studies, we use healthy and cancerous breast cell lines of different malignancy as well as primary cells from human cervix carcinoma. We apply a set of techniques to study their mechanical properties and interactions. The Optical Stretcher is used for whole cell rheology, while Cell-cell-adhesion forces are directly measured with a modified AFM. In combination with 3D segregation experiments in droplet cultures we try to clarify the role of surface tension in tumor spreading.

The interaction between LYVE-1 with hyaluronan on the cell surface may play a role in the diversity of adhesion to cancer cells.

PubMed

Du, Yan; Liu, Hua; He, Yiqing; Liu, Yiwen; Yang, Cuixia; Zhou, Muqing; Wang, Wenjuan; Cui, Lian; Hu, Jiajie; Gao, Feng

2013-01-01

Hyaluronan (HA), a simple disaccharide unit, can polymerize and is considered a primary component of the extracellular matrix, which has a wide range of biological functions. In recent years, HA was found on the surface of tumor cells. According to previous reports, differing HA content on the cell surface of tumor cells is closely related to lymph node metastases, but the mechanisms mediating this process remained unclear. This research intended to study the surface content of HA on tumor cells and analyze cell adhesive changes caused by the interaction between HA and its lymphatic endothelial receptor (LYVE-1). We screened and observed high HA content on HS-578T breast cells and low HA content on MCF-7 breast cells through particle exclusion, immunofluorescence and flow cytometry experiments. The expression of LYVE-1, the lymph-vessel specific HA receptor, was consistent with our previous report and enhanced the adhesion of HA(high)-HS-578T cells to COS-7(LYVE-1(+)) through HA in cell static adhesion and dynamic parallel plate flow chamber experiments. MCF-7 breast cells contain little HA on the surface; however, our results showed little adhesion difference between MCF-7 cells and COS-7(LYVE-1(+)) and COS-7(LYVE-1(-)) cells. Similar results were observed concerning the adhesion of HS-578T cells or MCF-7 cells to SVEC4-10 cells. Furthermore, we observed for the first time that the cell surface HA content of high transfer tumor cells was rich, and we visualized the cross-linking of HA cable structures, which may activate LYVE-1 on lymphatic endothelial cells, promoting tumor adhesion. In summary, high-low cell surface HA content of tumor cells through the interaction with LYVE-1 leads to adhesion differences.

Mycophenolate mofetil increases adhesion capacity of tumor cells in vitro.

PubMed

Blaheta, Roman A; Bogossian, Harilaos; Beecken, Wolf-Dietrich; Jonas, Dietger; Hasenberg, Christoph; Makarevic, Jasmina; Ogbomo, Henry; Bechstein, Wolf O; Oppermann, Elsie; Leckel, Kerstin; Cinatl, Jindrich

2003-12-27

The immunosuppressive drug mycophenolate mofetil (MMF) reduces expression of the heterophilic binding elements intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 and thereby prevents attachment of alloactivated leukocytes to donor endothelium. The authors speculated that MMF might further diminish receptors of the immunoglobulin superfamily which, however, act as homophilic binding elements. Because decrease of homophilic adhesion receptors correlates with tumor dissemination and metastasis, MMF could trigger development or recurrence of neoplastic tumors. The authors analyzed the influence of MMF on homotypic adhesion receptors and its consequence for tumor cell attachment to an endothelial cell monolayer. Neuroblastoma (NB) cells, which self-aggregate by means of the homophilic-binding element neural cell adhesion molecule (NCAM), were used. Effects of MMF on the 140- and 180-kDa NCAM isoforms were investigated quantitatively by flow cytometry, Western blot, and reverse-transcriptase (RT) polymerase chain reaction (PCR). The relevance of NCAM for tumor cell binding was proven by treating NB with NCAM antisense oligonucleotides. MMF profoundly increased the number of adherent NB cells, with a maximum effect at 0.1 microM, compared with controls. Decrease of NCAM on the cell surface was detected by flow cytometry. Western blot and RT-PCR demonstrated reduced protein and RNA levels of the 140- and 180-kDa isoforms. Treatment of NB cells with NCAM antisense oligonucleotides showed that reduced NCAM expression leads to enhanced tumor cell adhesion. MMF decreases NCAM receptors, which is associated with enhanced tumor cell invasiveness. The authors conclude that an MMF-based immunosuppressive regimen might increase the risk of tumor metastasis if this process is predominantly conveyed by means of homophilic adhesion proteins.

Desmoglein 3 regulates membrane trafficking of cadherins, an implication in cell-cell adhesion

PubMed Central

Moftah, Hanan; Dias, Kasuni; Apu, Ehsanul Hoque; Liu, Li; Uttagomol, Jutamas; Bergmeier, Lesley; Kermorgant, Stephanie; Wan, Hong

2017-01-01

ABSTRACT E-cadherin mediated cell-cell adhesion plays a critical role in epithelial cell polarization and morphogenesis. Our recent studies suggest that the desmosomal cadherin, desmoglein 3 (Dsg3) cross talks with E-cadherin and regulates its adhesive function in differentiating keratinocytes. However, the underlying mechanism remains not fully elucidated. Since E-cadherin trafficking has been recognized to be a central determinant in cell-cell adhesion and homeostasis we hypothesize that Dsg3 may play a role in regulating E-cadherin trafficking and hence the cell-cell adhesion. Here we investigated this hypothesis in cells with loss of Dsg3 function through RNAi mediated Dsg3 knockdown or the stable expression of the truncated mutant Dsg3ΔC. Our results showed that loss of Dsg3 resulted in compromised cell-cell adhesion and reduction of adherens junction and desmosome protein expression as well as the cortical F-actin formation. As a consequence, cells failed to polarize but instead displayed aberrant cell flattening. Furthermore, retardation of E-cadherin internalization and recycling was consistently observed in these cells during the process of calcium induced junction assembling. In contrast, enhanced cadherin endocytosis was detected in cells with overexpression of Dsg3 compared to control cells. Importantly, this altered cadherin trafficking was found to be coincided with the reduced expression and activity of Rab proteins, including Rab5, Rab7 and Rab11 which are known to be involved in E-cadherin trafficking. Taken together, our findings suggest that Dsg3 functions as a key in cell-cell adhesion through at least a mechanism of regulating E-cadherin membrane trafficking. PMID:27254775

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baeyens, Nicolas; Latrache, Iman; Yerna, Xavier

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 rolemore » 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.« less

A model study of factors involved in adhesion of Pseudomonas fluorescens to meat.

PubMed Central

Piette, J P; Idziak, E S

1992-01-01

A study was undertaken to investigate the factors involved in the adhesion of Pseudomonas fluorescens to model meat surfaces (tendon slices). Adhesion was fast (less than 2.5 min) and was not suppressed by killing the cells with UV, gamma rays, or heat, indicating that physiological activity was not required. In various salt solutions (NaCl, KCl, CaCl2, MgCl2), adhesion increased with increasing ionic strength up to 10 to 100 mM, suggesting that, at low ionic strengths, electrostatic interactions were involved in the adhesion process. At higher ionic strengths (greater than 10 to 100 mM) or in the presence of Al3+ ions, adhesion was sharply reduced. Selectively blocking of carboxyl or amino groups at the cell surface by chemical means did not affect adhesion. These groups are therefore not directly involved in an adhesive bond with tendon. Given a sufficient cell concentration (10(10) CFU.ml-1) in the adhesion medium, the surface of tendon was almost entirely covered with adherent bacteria. This suggests that if the adhesion is specific, the attachment sites on the tendon surface must be located within collagen or proteoglycan molecules. Images PMID:1444387

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.

Nandrolone decanoate is able to modulate proliferation and adhesion of myoblasts.

PubMed

Oliveira, E N; Fernandes, K P; Silva, C A; Oliveira, T S; Junior, J A; Bussadori, S K; Renno, A C; Mesquita-Ferrari, R A

2014-07-01

The search for a more efficient repair process of muscle injuries has become evident in clinical practice. The aim of the present study was to evaluate the effect of nandrolone decanoate (ND) on the proliferation, adhesion, and expression of myogenic regulatory factors (MRFs) in C2C12 cells.Methods. Cell proliferation and adhesion were assessed using an MTT assay. The expression of MRFs was assessed by real-time PCR.Results. ND applied at 10 or 25 µM concentration induced after 60 min an increase in adhesion, at 5 µM concentration induced after 5 days an increase in cell proliferation, and ND at 50 µM concentration led after 5 days to a decrease in cell proliferation in comparison with other groups. The steroid did not alter the expression of MRFs.Conclusions. The positive effects of ND regarding the proliferation and adhesion of C2C12 cells suggest that this steroid may have positive effects following a muscle injury.

Cell wall structures leading to cultivar differences in softening rates develop early during apple (Malus x domestica) fruit growth.

PubMed

Ng, Jovyn K T; Schröder, Roswitha; Sutherland, Paul W; Hallett, Ian C; Hall, Miriam I; Prakash, Roneel; Smith, Bronwen G; Melton, Laurence D; Johnston, Jason W

2013-11-19

There is a paucity of information regarding development of fruit tissue microstructure and changes in the cell walls during fruit growth, and how these developmental processes differ between cultivars with contrasting softening behaviour. In this study we compare two apple cultivars that show different softening rates during fruit development and ripening. We investigate whether these different softening behaviours manifest themselves late during ethylene-induced softening in the ripening phase, or early during fruit expansion and maturation. 'Scifresh' (slow softening) and 'Royal Gala' (rapid softening) apples show differences in cortical microstructure and cell adhesion as early as the cell expansion phase. 'Scifresh' apples showed reduced loss of firmness and greater dry matter accumulation compared with 'Royal Gala' during early fruit development, suggesting differences in resource allocation that influence tissue structural properties. Tricellular junctions in 'Scifresh' were rich in highly-esterified pectin, contributing to stronger cell adhesion and an increased resistance to the development of large airspaces during cell expansion. Consequently, mature fruit of 'Scifresh' showed larger, more angular shaped cells than 'Royal Gala', with less airspaces and denser tissue. Stronger cell adhesion in ripe 'Scifresh' resulted in tissue fracture by cell rupture rather than by cell-to-cell-separation as seen in 'Royal Gala'. CDTA-soluble pectin differed in both cultivars during development, implicating its involvement in cell adhesion. Low pectin methylesterase activity during early stages of fruit development coupled with the lack of immuno-detectable PG was associated with increased cell adhesion in 'Scifresh'. Our results indicate that cell wall structures leading to differences in softening rates of apple fruit develop early during fruit growth and well before the induction of the ripening process.

Cell wall structures leading to cultivar differences in softening rates develop early during apple (Malus x domestica) fruit growth

PubMed Central

2013-01-01

Background There is a paucity of information regarding development of fruit tissue microstructure and changes in the cell walls during fruit growth, and how these developmental processes differ between cultivars with contrasting softening behaviour. In this study we compare two apple cultivars that show different softening rates during fruit development and ripening. We investigate whether these different softening behaviours manifest themselves late during ethylene-induced softening in the ripening phase, or early during fruit expansion and maturation. Results ‘Scifresh’ (slow softening) and ‘Royal Gala’ (rapid softening) apples show differences in cortical microstructure and cell adhesion as early as the cell expansion phase. ‘Scifresh’ apples showed reduced loss of firmness and greater dry matter accumulation compared with ‘Royal Gala’ during early fruit development, suggesting differences in resource allocation that influence tissue structural properties. Tricellular junctions in ‘Scifresh’ were rich in highly-esterified pectin, contributing to stronger cell adhesion and an increased resistance to the development of large airspaces during cell expansion. Consequently, mature fruit of ‘Scifresh’ showed larger, more angular shaped cells than ‘Royal Gala’, with less airspaces and denser tissue. Stronger cell adhesion in ripe ‘Scifresh’ resulted in tissue fracture by cell rupture rather than by cell-to-cell-separation as seen in ‘Royal Gala’. CDTA-soluble pectin differed in both cultivars during development, implicating its involvement in cell adhesion. Low pectin methylesterase activity during early stages of fruit development coupled with the lack of immuno-detectable PG was associated with increased cell adhesion in ‘Scifresh’. Conclusions Our results indicate that cell wall structures leading to differences in softening rates of apple fruit develop early during fruit growth and well before the induction of the ripening process. PMID:24252512

Adhesion behavior of endothelial progenitor cells to endothelial cells in simple shear flow

NASA Astrophysics Data System (ADS)

Gong, Xiao-Bo; Li, Yu-Qing; Gao, Quan-Chao; Cheng, Bin-Bin; Shen, Bao-Rong; Yan, Zhi-Qiang; Jiang, Zong-Lai

2011-12-01

The adhesion of endothelial progenitor cells (EPCs) on endothelial cells (ECs) is one of the critical physiological processes for the regenesis of vascular vessels and the prevention of serious cardiovascular diseases. Here, the rolling and adhesion behavior of EPCs on ECs was studied numerically. A two-dimensional numerical model was developed based on the immersed boundary method for simulating the rolling and adhesion of cells in a channel flow. The binding force arising from the catch bond of a receptor and ligand pair was modeled with stochastic Monte Carlo method and Hookean spring model. The effect of tumor necrosis factor alpha (TNF- α) on the expression of the number of adhesion molecules in ECs was analyzed experimentally. A flow chamber system with CCD camera was set up to observe the top view of the rolling of EPCs on the substrate cultivated with ECs. Numerical results prove that the adhesion of EPC on ECs is closely related to membrane stiffness of the cell and shear rate of the flow. It also suggests that the adhesion force between EPC and EC by P-selectin glycoprotein ligand-1 only is not strong enough to bond the cell onto vessel walls unless contributions of other catch bond are considered. Experimental results demonstrate that TNF- α enhanced the expressions of VCAM, ICAM, P-selectin and E-selectin in ECs, which supports the numerical results that the rolling velocity of EPC on TNF- α treated EC substrate decreases obviously compared with its velocity on the untreated one. It is found that because the adhesion is affected by both the rolling velocity and the deformability of the cell, an optimal stiffness of EPC may exist at a given shear rate of flow for achieving maximum adhesion rates.

Curcumin inhibits activation induced by urban particulate material or titanium dioxide nanoparticles in primary human endothelial cells

PubMed Central

Montiel-Dávalos, Angélica; Silva Sánchez, Guadalupe Jazmin; Huerta-García, Elizabeth; Rueda-Romero, Cristhiam; Soca Chafre, Giovanny; Mitre-Aguilar, Irma B.; Alfaro-Moreno, Ernesto; Pedraza-Chaverri, José

2017-01-01

Curcumin has protective effects against toxic agents and shows preventive properties for various diseases. Particulate material with an aerodynamic diameter of ≤10 μm (PM10) and titanium dioxide nanoparticles (TiO2-NPs) induce endothelial dysfunction and activation. We explored whether curcumin is able to attenuate different events related to endothelial activation. This includes adhesion, expression of adhesion molecules and oxidative stress induced by PM10 and TiO2-NPs. Human umbilical vein endothelial cells (HUVEC) were treated with 1, 10 and 100 μM curcumin for 1 h and then exposed to PM10 at 3 μg/cm2 or TiO2-NPs at 10 μg/cm2. Cell adhesion was evaluated by co-culture with U937 human myelomonocytic cells. Adhesion molecules expression was measured by flow cytometry after 3 or 24 h of exposure. Oxidative stress was determined by 2,7-dichlorodihydrofluorescein (H2DCF) oxidation. PM10 and TiO2-NPs induced the adhesion of U937 cells and the expression of E- and P-selectins, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and platelet-endothelial cell adhesion molecule-1 (PECAM-1). The expression of E- and P-selectins matched the adhesion of monocytes to HUVEC after 3 h. In HUVEC treated with 1 or 10 μM curcumin, the expression of adhesion molecules and monocytes adhesion was significantly diminished. Curcumin also partially reduced the H2DCF oxidation induced by PM10 and TiO2-NPs. Our results suggest an anti-inflammatory and antioxidant role by curcumin attenuating the activation caused on endothelial cells by exposure to particles. Therefore, curcumin could be useful in the treatment of diseases where an inflammatory process and endothelial activation are involved. PMID:29244817

Single Cell Force Spectroscopy for Quantification of Cellular Adhesion on Surfaces

NASA Astrophysics Data System (ADS)

Christenson, Wayne B.

Cell adhesion is an important aspect of many biological processes. The atomic force microscope (AFM) has made it possible to quantify the forces involved in cellular adhesion using a technique called single cell force spectroscopy (SCFS). AFM based SCFS offers versatile control over experimental conditions for probing directly the interaction between specific cell types and specific proteins, surfaces, or other cells. Transmembrane integrins are the primary proteins involved in cellular adhesion to the extra cellular matix (ECM). One of the chief integrins involved in the adhesion of leukocyte cells is alpha Mbeta2 (Mac-1). The experiments in this dissertation quantify the adhesion of Mac-1 expressing human embryonic kidney (HEK Mac-1), platelets, and neutrophils cells on substrates with different concentrations of fibrinogen and on fibrin gels and multi-layered fibrinogen coated fibrin gels. It was shown that multi-layered fibrinogen reduces the adhesion force of these cells considerably. A novel method was developed as part of this research combining total internal reflection microscopy (TIRFM) with SCFS allowing for optical microscopy of HEK Mac-1 cells interacting with bovine serum albumin (BSA) coated glass after interacting with multi-layered fibrinogen. HEK Mac-1 cells are able to remove fibrinogen molecules from the multi-layered fibrinogen matrix. An analysis methodology for quantifying the kinetic parameters of integrin-ligand interactions from SCFS experiments is proposed, and the kinetic parameters of the Mac-1 fibrinogen bond are quantified. Additional SCFS experiments quantify the adhesion of macrophages and HEK Mac-1 cells on functionalized glass surfaces and normal glass surfaces. Both cell types show highest adhesion on a novel functionalized glass surface that was prepared to induce macrophage fusion. These experiments demonstrate the versatility of AFM based SCFS, and how it can be applied to address many questions in cellular biology offering quantitative insights.

Biofriendly bonding processes for nanoporous implantable SU-8 microcapsules for encapsulated cell therapy.

PubMed

Nemani, Krishnamurthy; Kwon, Joonbum; Trivedi, Krutarth; Hu, Walter; Lee, Jeong-Bong; Gimi, Barjor

2011-01-01

Mechanically robust, cell encapsulating microdevices fabricated using photolithographic methods can lead to more efficient immunoisolation in comparison to cell encapsulating hydrogels. There is a need to develop adhesive bonding methods which can seal such microdevices under physiologically friendly conditions. We report the bonding of SU-8 based substrates through (i) magnetic self assembly, (ii) using medical grade photocured adhesive and (iii) moisture and photochemical cured polymerization. Magnetic self-assembly, carried out in biofriendly aqueous buffers, provides weak bonding not suitable for long term applications. Moisture cured bonding of covalently modified SU-8 substrates, based on silanol condensation, resulted in weak and inconsistent bonding. Photocured bonding using a medical grade adhesive and of acrylate modified substrates provided stable bonding. Of the methods evaluated, photocured adhesion provided the strongest and most stable adhesion.

Spatial self-organization in hybrid models of multicellular adhesion

NASA Astrophysics Data System (ADS)

Bonforti, Adriano; Duran-Nebreda, Salva; Montañez, Raúl; Solé, Ricard

2016-10-01

Spatial self-organization emerges in distributed systems exhibiting local interactions when nonlinearities and the appropriate propagation of signals are at work. These kinds of phenomena can be modeled with different frameworks, typically cellular automata or reaction-diffusion systems. A different class of dynamical processes involves the correlated movement of agents over space, which can be mediated through chemotactic movement or minimization of cell-cell interaction energy. A classic example of the latter is given by the formation of spatially segregated assemblies when cells display differential adhesion. Here, we consider a new class of dynamical models, involving cell adhesion among two stochastically exchangeable cell states as a minimal model capable of exhibiting well-defined, ordered spatial patterns. Our results suggest that a whole space of pattern-forming rules is hosted by the combination of physical differential adhesion and the value of probabilities modulating cell phenotypic switching, showing that Turing-like patterns can be obtained without resorting to reaction-diffusion processes. If the model is expanded allowing cells to proliferate and die in an environment where diffusible nutrient and toxic waste are at play, different phases are observed, characterized by regularly spaced patterns. The analysis of the parameter space reveals that certain phases reach higher population levels than other modes of organization. A detailed exploration of the mean-field theory is also presented. Finally, we let populations of cells with different adhesion matrices compete for reproduction, showing that, in our model, structural organization can improve the fitness of a given cell population. The implications of these results for ecological and evolutionary models of pattern formation and the emergence of multicellularity are outlined.

Gastrin-releasing peptide induces monocyte adhesion to vascular endothelium by upregulating endothelial adhesion molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Mi-Kyoung; Park, Hyun-Joo; Department of Dental Pharmacology, BK21 PLUS Project, School of Dentistry, Pusan National University, Yangsan 626-870

Gastrin-releasing peptide (GRP) is a neuropeptide that plays roles in various pathophysiological conditions including inflammatory diseases in peripheral tissues; however, little is known about whether GRP can directly regulate endothelial inflammatory processes. In this study, we showed that GRP promotes the adhesion of leukocytes to human umbilical vein endothelial cells (HUVECs) and the aortic endothelium. GRP increased the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) by activating nuclear factor-κB (NF-κB) in endothelial cells. In addition, GRP activated extracellular signal-regulated kinase 1/2 (ERK1/2), p38MAPK, and AKT, and the inhibition of these signaling pathways significantly reduced GRP-inducedmore » monocyte adhesion to the endothelium. Overall, our results suggested that GRP may cause endothelial dysfunction, which could be of particular relevance in the development of vascular inflammatory disorders. - Highlights: • GRP induces adhesion of monocytes to vascular endothelium. • GRP increases the expression of endothelial adhesion molecules through the activation of NF-κB. • ERK1/2, p38MAPK, and Akt pathways are involved in the GRP-induced leukocyte adhesiveness to endothelium.« less

Alternatively activated macrophages upregulate mesothelial expression of P-selectin to enhance adhesion of ovarian cancer cells.

PubMed

Carroll, Molly J; Fogg, Kaitlin C; Patel, Harin A; Krause, Harris B; Mancha, Anne-Sophie; Patankar, Manish S; Weisman, Paul S; Barroilhet, Lisa; Kreeger, Pamela K

2018-05-08

Peritoneal metastasis of high-grade serous ovarian cancer (HGSOC) occurs when tumor cells suspended in ascites adhere to mesothelial cells. Despite the strong relationship between metastatic burden and prognosis in HGSOC, there are currently no therapies specifically targeting the metastatic process. We utilized a co-culture model and multivariate analysis to examine how interactions between tumor cells, mesothelial cells, and alternatively-activated macrophages (AAMs) influence the adhesion of tumor cells to mesothelial cells. We found that AAM-secreted MIP-1β activates CCR5/PI3K signaling in mesothelial cells, resulting in expression of P-selectin on the mesothelial cell surface. Tumor cells attached to this de novo P-selectin through CD24, resulting in increased tumor cell adhesion in static conditions and rolling under flow. C57/BL6 mice treated with MIP-1β exhibited increased P-selectin expression on mesothelial cells lining peritoneal tissues, which enhanced CaOV3 adhesion ex vivo and ID8 adhesion in vivo. Analysis of samples from HGSOC patients confirmed increased MIP-1β and P-selectin, suggesting that this novel multi-cellular mechanism could be targeted to slow or stop metastasis in HGSOC by repurposing anti- CCR5 and P-selectin therapies developed for other indications. Copyright ©2018, American Association for Cancer Research.

Investigation of the Antimetastatic Effects of Agents that Inhibit Cell Adhesion or Protein Glycosylation

PubMed Central

Humphries, Martin J.; Matsumoto, Kazue; White, Sandra L.; Olden, Kenneth

1987-01-01

In this overview the authors describe their recent attempts to specifically interfere with the metastatic spread of B16-F10 melanoma cells. Using the experimental metastasis model system, inhibitory effects of (1) coinjection of cells with synthetic peptides derived from the glycoprotein fibronectin, which possess the ability to disrupt cell adhesion, and (2) treatment of cells with inhibitors of protein glycosylation and oligosaccharide processing have been examined. PMID:3295262

CD15s/CD62E Interaction Mediates the Adhesion of Non-Small Cell Lung Cancer Cells on Brain Endothelial Cells: Implications for Cerebral Metastasis.

PubMed

Jassam, Samah A; Maherally, Zaynah; Smith, James R; Ashkan, Keyoumars; Roncaroli, Federico; Fillmore, Helen L; Pilkington, Geoffrey J

2017-07-10

Expression of the cell adhesion molecule (CAM), Sialyl Lewis X (CD15s) correlates with cancer metastasis, while expression of E-selectin (CD62E) is stimulated by TNF-α. CD15s/CD62E interaction plays a key role in the homing process of circulating leukocytes. We investigated the heterophilic interaction of CD15s and CD62E in brain metastasis-related cancer cell adhesion. CD15s and CD62E were characterised in human brain endothelium (hCMEC/D3), primary non-small cell lung cancer (NSCLC) (COR-L105 and A549) and metastatic NSCLC (SEBTA-001 and NCI-H1299) using immunocytochemistry, Western blotting, flow cytometry and immunohistochemistry in human brain tissue sections. TNF-α (25 pg/mL) stimulated extracellular expression of CD62E while adhesion assays, under both static and physiological flow live-cell conditions, explored the effect of CD15s-mAb immunoblocking on adhesion of cancer cell-brain endothelium. CD15s was faintly expressed on hCMEC/D3, while high levels were observed on primary NSCLC cells with expression highest on metastatic NSCLC cells ( p < 0.001). CD62E was highly expressed on hCMEC/D3 cells activated with TNF-α, with lower levels on primary and metastatic NSCLC cells. CD15s and CD62E were expressed on lung metastatic brain biopsies. CD15s/CD62E interaction was localised at adhesion sites of cancer cell-brain endothelium. CD15s immunoblocking significantly decreased cancer cell adhesion to brain endothelium under static and shear stress conditions ( p < 0.001), highlighting the role of CD15s-CD62E interaction in brain metastasis.

Role of cell division and self-propulsion in self-organization of 2D cell co-cultures

NASA Astrophysics Data System (ADS)

Das, Moumita; Dey, Supravat; Wu, Mingming; Ma, Minglin

Self-organization of cells is a key process in developmental and cancer biology. The differential adhesion hypothesis (DAH), which assumes cells as equilibrium liquid droplets and relates the self-assembly of cells to differences in inter-cellular adhesiveness, has been very successful in explaining cellular organization during morphogenesis where neighboring cells have the same non-equilibrium properties (motility, proliferation rate). However, recently it has been experimentally shown that for a co-culture of two different cell types proliferating at different rates, the resulting spatial morphologies cannot be explained using the DAH alone. Motivated by this, we develop and study a two-dimensional model of a cell co-culture that includes cell division and self-propulsion in addition to cell-cell adhesion, and systemically study how cells with significantly different adhesion, motility, and proliferation rate dynamically organize themselves in a spatiotemporal and context-dependent manner. Our results may help to understand how differential equilibrium and non-equilibrium properties cooperate and compete leading to different morphologies during tumor development, with important consequences for invasion and metastasis

Design and use of an artificial capillary in the study of metastatic cell adhesion

NASA Astrophysics Data System (ADS)

Rafi, Adam; Peramo, Antonio; Boren, Rebecca; Heim, August; Matthews, William G.

2006-03-01

To improve the quality of life of patients with cancer, treatments will need to both minimize existing tumors and reduce the metastasis of cancer cells. The effectiveness of potential treatments on existing tumors can be directly probed, but anti-metastasis treatments are difficult to quantify. Therefore, a detailed understanding of the metastatic process is required for drug design. Details of the metastatic deposition of tumor cells in the circulatory system are not well understood. We are investigating the binding of tumor cells to an artificial endothelium. The model system allows for control over molecular composition at the interface, presenting the proteoglycans (PGs) found in the glycocalyx to tumor cells under shear flow conditions. Whether rolling or static adhesion is preferred, as well as what mechanical properties of the interaction between the cells and the PGs are important is to be determined. The outcomes of these experiments will help guide the search for pharmaceuticals that can disrupt the metastatic process at the endothelial adhesion step.

Calcium influx through the TRPV1 channel of endothelial cells (ECs) correlates with a stronger adhesion between monocytes and ECs.

PubMed

Himi, N; Hamaguchi, A; Hashimoto, K; Koga, T; Narita, K; Miyamoto, O

2012-01-01

Atherosclerosis is thought to be initiated by the transendothelial migration of monocytes. In the early stage of this process, the adhesion of monocytes to endothelial cells is supported by an increase in the intracellular concentration of calcium ion ([Ca(2+)]i) in endothelial cells. However, the main source of Ca(2+) has been unclear. In this study, the changes in ionic transmittance and [Ca(2+)]i due to the adhesion of monocytes were continuously measured by an electrophysiological technique and fluorescent imaging. Especially, we focused on transient receptor potential vanilloid channel 1 (TRPV1) as a Ca(2+) channel that could influence the adhesion of monocytes. Whole-cell current was continuously recorded in human umbilical vein endothelial cells (HUVECs) by a patch electrode. The adhesion of monocytes (THP-1) induced a transient inward current in HUVECs, as well as an elevation of [Ca(2+)]i. This inward element was abolished by the application of 100 nM SB366,791, a selective antagonist of TRPV1 channel. Furthermore, SB366,791 significantly decreased the number of THP-1 cells that adhered to HUVECs (control: 231 ± 38, SB366,791: 96 ± 16 cells/mm2). These results suggest that an inward calcium current via the TRPV1 channels of endothelial cells correlates with a stronger adhesion between monocytes and endothelial cells.

Interactions with nanoscale topography: adhesion quantification and signal transduction in cells of osteogenic and multipotent lineage.

PubMed

Biggs, Manus J P; Richards, R Geoff; Gadegaard, Nikolaj; McMurray, Rebecca J; Affrossman, Stanley; Wilkinson, Chris D W; Oreffo, Richard O C; Dalby, Mathew J

2009-10-01

Polymeric medical devices widely used in orthopedic surgery play key roles in fracture fixation and orthopedic implant design. Topographical modification and surface micro-roughness of these devices regulate cellular adhesion, a process fundamental in the initiation of osteoinduction and osteogenesis. Advances in fabrication techniques have evolved the field of surface modification; in particular, nanotechnology has allowed the development of nanoscale substrates for the investigation into cell-nanofeature interactions. In this study human osteoblasts (HOBs) were cultured on ordered nanoscale pits and random nano "craters" and "islands". Adhesion subtypes were quantified by immunofluorescent microscopy and cell-substrate interactions investigated via immuno-scanning electron microscopy. To investigate the effects of these substrates on cellular function 1.7 k microarray analysis was used to establish gene profiles of enriched STRO-1+ progenitor cell populations cultured on these nanotopographies. Nanotopographies affected the formation of adhesions on experimental substrates. Adhesion formation was prominent on planar control substrates and reduced on nanocrater and nanoisland topographies; nanopits, however, were shown to inhibit directly the formation of large adhesions. STRO-1+ progenitor cells cultured on experimental substrates revealed significant changes in genetic expression. This study implicates nanotopographical modification as a significant modulator of osteoblast adhesion and cellular function in mesenchymal populations.

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

Surface wettability of plasma SiOx:H nanocoating-induced endothelial cells' migration and the associated FAK-Rho GTPases signalling pathways

PubMed Central

Shen, Yang; Wang, Guixue; Huang, Xianliang; Zhang, Qin; Wu, Jiang; Tang, Chaojun; Yu, Qingsong; Liu, Xiaoheng

2012-01-01

Vascular endothelial cell (EC) adhesion and migration are essential processes in re-endothelialization of implanted biomaterials. There is no clear relationship and mechanism between EC adhesion and migration behaviour on surfaces with varying wettabilities. As model substrates, plasma SiOx:H nanocoatings with well-controlled surface wettability (with water contact angles in the range of 98.5 ± 2.3° to 26.3 ± 4.0°) were used in this study to investigate the effects of surface wettability on cell adhesion/migration and associated protein expressions in FAK-Rho GTPases signalling pathways. It was found that EC adhesion/migration showed opposite behaviour on the hydrophilic and hydrophobic surfaces (i.e. hydrophobic surfaces promoted EC migration but were anti-adhesions). The number of adherent ECs showed a maximum on hydrophilic surfaces, while cells adhered to hydrophobic surfaces exhibited a tendency for cell migration. The focal adhesion kinase (FAK) inhibitor targeting the Y-397 site of FAK could significantly inhibit cell adhesion/migration, suggesting that EC adhesion and migration on surfaces with different wettabilities involve (p)FAK and its downstream signalling pathways. Western blot results suggested that the FAK-Rho GTPases signalling pathways were correlative to EC migration on hydrophobic plasma SiOx:H surfaces, but uncertain to hydrophilic surfaces. This work demonstrated that surface wettability could induce cellular behaviours that were associated with different cellular signalling events. PMID:21715399

Integrin-specific mechanoresponses to compression and extension probed by cylindrical flat-ended AFM tips in lung cells.

PubMed

Acerbi, Irene; Luque, Tomás; Giménez, Alícia; Puig, Marta; Reguart, Noemi; Farré, Ramon; Navajas, Daniel; Alcaraz, Jordi

2012-01-01

Cells from lung and other tissues are subjected to forces of opposing directions that are largely transmitted through integrin-mediated adhesions. How cells respond to force bidirectionality remains ill defined. To address this question, we nanofabricated flat-ended cylindrical Atomic Force Microscopy (AFM) tips with ~1 µm(2) cross-section area. Tips were uncoated or coated with either integrin-specific (RGD) or non-specific (RGE/BSA) molecules, brought into contact with lung epithelial cells or fibroblasts for 30 s to form focal adhesion precursors, and used to probe cell resistance to deformation in compression and extension. We found that cell resistance to compression was globally higher than to extension regardless of the tip coating. In contrast, both tip-cell adhesion strength and resistance to compression and extension were the highest when probed at integrin-specific adhesions. These integrin-specific mechanoresponses required an intact actin cytoskeleton, and were dependent on tyrosine phosphatases and Ca(2+) signaling. Cell asymmetric mechanoresponse to compression and extension remained after 5 minutes of tip-cell adhesion, revealing that asymmetric resistance to force directionality is an intrinsic property of lung cells, as in most soft tissues. Our findings provide new insights on how lung cells probe the mechanochemical properties of the microenvironment, an important process for migration, repair and tissue homeostasis.

CRYOPRESERVATION EFFECTS ON RECOMBINANT MYOBLASTS ENCAPSULATED IN ADHESIVE ALGINATE HYDROGELS

PubMed Central

Ahmad, Hajira F.; Sambanis, Athanassios

2013-01-01

Cell encapsulation in hydrogels is widely used in tissue engineering applications, including encapsulation of islets or other insulin-secreting cells in pancreatic substitutes. Use of adhesive, bio-functionalized hydrogels is receiving increasing attention, as cell-matrix interactions in 3-D can be important for various cell processes. With pancreatic substitutes, studies have indicated benefits of 3-D adhesion on the viability and/or function of insulin-secreting cells. As long-term storage of microencapsulated cells is critical for their clinical translation, cryopreservation of cells in hydrogels is actively being investigated. Previous studies have examined the cryopreservation response of cells encapsulated in non-adhesive hydrogels using conventional freezing and/or vitrification (ice-free cryopreservation), however, none have systematically compared the two cryopreservation methods with cells encapsulated within an adhesive 3-D environment. The latter would be significant, as evidence suggests adhesion influences cellular response to cryopreservation. Thus, the objective of this study was to determine the response to conventional freezing and vitrification of insulin-secreting cells encapsulated in an adhesive biomimetic hydrogel. Recombinant insulin-secreting C2C12 myoblasts were encapsulated in oxidized RGD-alginate and cultured 1 or 4 days post-encapsulation, cryopreserved, and assessed up to 3 days post-warming for metabolic activity and insulin secretion, and one day post-warming for cell morphology. Besides certain transient differences of the vitrified group relative to the Fresh control, both conventional freezing and vitrification maintained metabolism, secretion and morphology of the recombinant C2C12 cells. Thus, due to a simpler procedure and slightly superior results, conventional freezing is recommended over vitrification for the cryopreservation of C2C12 cells in oxidized RGD-modified alginate. PMID:23499987

TM9/Phg1 and SadA proteins control surface expression and stability of SibA adhesion molecules in Dictyostelium.

PubMed

Froquet, Romain; le Coadic, Marion; Perrin, Jackie; Cherix, Nathalie; Cornillon, Sophie; Cosson, Pierre

2012-02-01

TM9 proteins form a family of conserved proteins with nine transmembrane domains essential for cellular adhesion in many biological systems, but their exact role in this process remains unknown. In this study, we found that genetic inactivation of the TM9 protein Phg1A dramatically decreases the surface levels of the SibA adhesion molecule in Dictyostelium amoebae. This is due to a decrease in sibA mRNA levels, in SibA protein stability, and in SibA targeting to the cell surface. A similar phenotype was observed in cells devoid of SadA, a protein that does not belong to the TM9 family but also exhibits nine transmembrane domains and is essential for cellular adhesion. A contact site A (csA)-SibA chimeric protein comprising only the transmembrane and cytosolic domains of SibA and the extracellular domain of the Dictyostelium surface protein csA also showed reduced stability and relocalization to endocytic compartments in phg1A knockout cells. These results indicate that TM9 proteins participate in cell adhesion by controlling the levels of adhesion proteins present at the cell surface.

Glucosamine Treatment-mediated O-GlcNAc Modification of Paxillin Depends on Adhesion State of Rat Insulinoma INS-1 Cells*

PubMed Central

Kwak, Tae Kyoung; Kim, Hyeonjung; Jung, Oisun; Lee, Sin-Ae; Kang, Minkyung; Kim, Hyun Jeong; Park, Ji-Min; Kim, Sung-Hoon; Lee, Jung Weon

2010-01-01

Protein-protein interactions and/or signaling activities at focal adhesions, where integrin-mediated adhesion to extracellular matrix occurs, are critical for the regulation of adhesion-dependent cellular functions. Although the phosphorylation and activities of focal adhesion molecules have been intensively studied, the effects of the O-GlcNAc modification of their Ser/Thr residues on cellular functions have been largely unexplored. We investigated the effects of O-GlcNAc modification on actin reorganization and morphology of rat insulinoma INS-1 cells after glucosamine (GlcN) treatment. We found that paxillin, a key adaptor molecule in focal adhesions, could be modified by O-GlcNAc in INS-1 cells treated with GlcN and in pancreatic islets from mice treated with streptozotocin. Ser-84/85 in human paxillin appeared to be modified by O-GlcNAc, which was inversely correlated to Ser-85 phosphorylation (Ser-83 in rat paxillin). Integrin-mediated adhesion signaling inhibited the GlcN treatment-enhanced O-GlcNAc modification of paxillin. Adherent INS-1 cells treated with GlcN showed restricted protrusions, whereas untreated cells showed active protrusions for multiple-elongated morphologies. Upon GlcN treatment, expression of a triple mutation (S83A/S84A/S85A) resulted in no further restriction of protrusions. Together these observations suggest that murine pancreatic β cells may have restricted actin organization upon GlcN treatment by virtue of the O-GlcNAc modification of paxillin, which can be antagonized by a persistent cell adhesion process. PMID:20829364

CD15s/CD62E Interaction Mediates the Adhesion of Non-Small Cell Lung Cancer Cells on Brain Endothelial Cells: Implications for Cerebral Metastasis

PubMed Central

Jassam, Samah A.; Maherally, Zaynah; Ashkan, Keyoumars; Roncaroli, Federico; Fillmore, Helen L.; Pilkington, Geoffrey J.

2017-01-01

Expression of the cell adhesion molecule (CAM), Sialyl Lewis X (CD15s) correlates with cancer metastasis, while expression of E-selectin (CD62E) is stimulated by TNF-α. CD15s/CD62E interaction plays a key role in the homing process of circulating leukocytes. We investigated the heterophilic interaction of CD15s and CD62E in brain metastasis-related cancer cell adhesion. CD15s and CD62E were characterised in human brain endothelium (hCMEC/D3), primary non-small cell lung cancer (NSCLC) (COR-L105 and A549) and metastatic NSCLC (SEBTA-001 and NCI-H1299) using immunocytochemistry, Western blotting, flow cytometry and immunohistochemistry in human brain tissue sections. TNF-α (25 pg/mL) stimulated extracellular expression of CD62E while adhesion assays, under both static and physiological flow live-cell conditions, explored the effect of CD15s-mAb immunoblocking on adhesion of cancer cell–brain endothelium. CD15s was faintly expressed on hCMEC/D3, while high levels were observed on primary NSCLC cells with expression highest on metastatic NSCLC cells (p < 0.001). CD62E was highly expressed on hCMEC/D3 cells activated with TNF-α, with lower levels on primary and metastatic NSCLC cells. CD15s and CD62E were expressed on lung metastatic brain biopsies. CD15s/CD62E interaction was localised at adhesion sites of cancer cell–brain endothelium. CD15s immunoblocking significantly decreased cancer cell adhesion to brain endothelium under static and shear stress conditions (p < 0.001), highlighting the role of CD15s–CD62E interaction in brain metastasis. PMID:28698503

Dynamic pattern of endothelial cell adhesion molecule expression in muscle and perineural vessels from patients with classic polyarteritis nodosa.

PubMed

Coll-Vinent, B; Cebrián, M; Cid, M C; Font, C; Esparza, J; Juan, M; Yagüe, J; Urbano-Márquez, A; Grau, J M

1998-03-01

To investigate endothelial cell adhesion molecule expression in vessels from patients with classic polyarteritis nodosa (PAN). Frozen sections of 21 muscle and 16 nerve samples from 30 patients with biopsy-proven PAN and 12 histologically normal muscle and 2 histologically normal nerve samples from 12 controls were studied immunohistochemically, using specific monoclonal antibodies (MAb) that recognize adhesion molecules. Adhesion molecules identified were intercellular adhesion molecule 1 (ICAM-1), ICAM-2, ICAM-3, vascular cell adhesion molecule 1 (VCAM-1), platelet endothelial cell adhesion molecule 1 (PECAM-1), E-selectin, P-selectin, L-selectin, lymphocyte function-associated antigen 1 (LFA-1), and very late activation antigen 4 (VLA-4). Neutrophils were identified with a MAb recognizing neutrophil elastase. Endothelial cells were identified with the lectin ulex europaeus. In early lesions, expression of PECAM-1, ICAM-1, ICAM-2, and P-selectin was similar to that in control samples, and VCAM-1 and E-selectin were induced in vascular endothelium. In advanced lesions, immunostaining for adhesion molecules diminished or disappeared in luminal endothelium, whereas these molecules were clearly expressed in microvessels within and surrounding inflamed vessels. Staining in endothelia from vessels in a healing stage tended to be negative. A high proportion of infiltrating leukocytes expressed LFA-1 and VLA-4, and only a minority expressed L-selectin. No relationship between the expression pattern of adhesion molecules and clinical features, disease duration, or previous corticosteroid treatment was observed. Endothelial adhesion molecule expression in PAN is a dynamic process that varies according to the histopathologic stage of the vascular lesions. The preferential expression of constitutive and inducible adhesion molecules in microvessels suggests that angiogenesis contributes to the persistence of inflammatory infiltration in PAN.

FERMT2 links cortical actin structures, plasma membrane tension and focal adhesion function to stabilize podocyte morphology.

PubMed

Yasuda-Yamahara, M; Rogg, M; Frimmel, J; Trachte, P; Helmstaedter, M; Schroder, P; Schiffer, M; Schell, C; Huber, T B

2018-01-11

Simplification and retraction of podocyte protrusions, generally termed as foot process effacement, is a uniform pathological pattern observed in the majority of glomerular disease, including focal segmental glomerulosclerosis. However, it is still incompletely understood how the interaction of cortical actin structures, actomyosin contractility and focal adhesions, is being orchestrated to control foot process morphology in health and disease. By uncovering the functional role of fermitin family member 2 (FERMT2 or kindlin-2) in podocytes, we provide now evidence, how cell-extracellular matrix (ECM) interactions modulate membrane tension and actomyosin contractility. A genetic modeling approach was applied by deleting FERMT2 in a set of in vivo systems as well as in CRISPR/Cas9 modified human podocytes. Loss of FERMT2 results in altered cortical actin composition, cell cortex destabilization associated with plasma membrane blebbing and a remodeling of focal adhesions. We further show that FERMT2 knockout podocytes have high levels of RhoA activation and concomitantly increased actomyosin contractility. Inhibition of actomyosin tension reverses the membrane blebbing phenotype. Thus, our findings establish a direct link between cell-matrix adhesions, cortical actin structures and plasma membrane tension allowing to better explain cell morphological changes in foot process effacement. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Influence of adhesion and friction on the geometry of packings of spherical particles

NASA Astrophysics Data System (ADS)

Martin, C. L.; Bordia, R. K.

2008-03-01

We study the effect of both adhesion and friction on the geometry of monosized packings of spheres by means of discrete element simulations. We use elastic properties that are characteristic of materials typically used for particulate processing (Young’s modulus in the range 20-200 GPa). The geometrical features, both global and local, of the packings are studied using a variety of approaches in order to investigate their ability to quantify the effect of adhesion and/or friction. We show that both adhesion and friction interaction decrease the packing fraction. The very localized ordering that adhesion triggers is particularly investigated by use of the radial distribution function, the ordering parameter Q6 , and four triclinic cells that allow a description of the microstructure at the local level. We show that the probability of occurrence of these triclinic cells is approximately proportional to their degree of freedom when neither adhesion nor friction plays a role. We find that the introduction of adhesive interactions increases the probability of occurrence of those cells that have the lowest degree of freedom.

Micrometer scale spacings between fibronectin nanodots regulate cell morphology and focal adhesions

NASA Astrophysics Data System (ADS)

Horzum, Utku; Ozdil, Berrin; Pesen-Okvur, Devrim

2014-04-01

Cell adhesion to extracellular matrix is an important process for both health and disease states. Surface protein patterns that are topographically flat, and do not introduce other chemical, topographical or rigidity related functionality and, more importantly, that mimic the organization of the in vivo extracellular matrix are desired. Previous work showed that vinculin and cytoskeletal organization are modulated by size and shape of surface nanopatterns. However, quantitative analysis on cell morphology and focal adhesions as a function of micrometer scale spacings of FN nanopatterns was absent. Here, electron beam lithography was used to pattern fibronectin nanodots with micrometer scale spacings on a K-casein background on indium tin oxide coated glass which, unlike silicon, is transparent and thus suitable for many light microscopy techniques. Exposure times were significantly reduced using the line exposure mode with micrometer scale step sizes. Micrometer scale spacings of 2, 4 and 8 μm between fibronectin nanodots proved to modulate cell adhesion through modification of cell area, focal adhesion number, size and circularity. Overall, cell behavior was shown to shift at the apparent threshold of 4 μm spacing. The findings presented here offer exciting new opportunities for cell biology research.

Collisions of deformable cells lead to collective migration

NASA Astrophysics Data System (ADS)

Löber, Jakob; Ziebert, Falko; Aranson, Igor S.

2015-03-01

Collective migration of eukaryotic cells plays a fundamental role in tissue growth, wound healing and immune response. The motion, arising spontaneously or in response to chemical and mechanical stimuli, is also important for understanding life-threatening pathologies, such as cancer and metastasis formation. We present a phase-field model to describe the movement of many self-organized, interacting cells. The model takes into account the main mechanisms of cell motility - acto-myosin dynamics, as well as substrate-mediated and cell-cell adhesion. It predicts that collective cell migration emerges spontaneously as a result of inelastic collisions between neighboring cells: collisions lead to a mutual alignment of the cell velocities and to the formation of coherently-moving multi-cellular clusters. Small cell-to-cell adhesion, in turn, reduces the propensity for large-scale collective migration, while higher adhesion leads to the formation of moving bands. Our study provides valuable insight into biological processes associated with collective cell motility.

Measurement of cell adhesion force by vertical forcible detachment using an arrowhead nanoneedle and atomic force microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ryu, Seunghwan; Hashizume, Yui; Mishima, Mari

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 tomore » 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.« less

Multifunctional Self-Adhesive Fibrous Layered Matrix (FiLM) for Tissue Glues and Therapeutic Carriers.

PubMed

Yoon, Ye-Eun; Im, Byung Gee; Kim, Jung-Suk; Jang, Jae-Hyung

2017-01-09

Tissue adhesives, which inherently serve as wound sealants or as hemostatic agents, can be further augmented to acquire crucial functions as scaffolds, thereby accelerating wound healing or elevating the efficacy of tissue regeneration. Herein, multifunctional adherent fibrous matrices, acting as self-adhesive scaffolds capable of cell/gene delivery, were devised by coaxially electrospinning poly(caprolactone) (PCL) and poly(vinylpyrrolidone) (PVP). Wrapping the building block PCL fibers with the adherent PVP layers formed film-like fibrous matrices that could rapidly adhere to wet biological surfaces, referred to as fibrous layered matrix (FiLM) adhesives. The inclusion of ionic salts (i.e., dopamine hydrochloride) in the sheath layers generated spontaneously multilayered fibrous adhesives, whose partial layers could be manually peeled off, termed derivative FiLM (d-FiLM). In the context of scaffolds/tissue adhesives, both FiLM and d-FiLM demonstrated almost identical characteristics (i.e., sticky, mechanical, and performances as cell/gene carriers). Importantly, the single FiLM-process can yield multiple sets of d-FiLM by investing the same processing time, materials, and labor required to form a single conventional adhesive fibrous mat, thereby highlighting the economic aspects of the process. The FiLM/d-FiLM offer highly impacting contributions to many biomedical applications, especially in fields that require urgent aids (e.g., endoscopic surgeries, implantation in wet environments, severe wounds).

Increased adhesive and inflammatory properties in blood outgrowth endothelial cells from sickle cell anemia patients.

PubMed

Sakamoto, Tatiana Mary; Lanaro, Carolina; Ozelo, Margareth Castro; Garrido, Vanessa Tonin; Olalla-Saad, Sara Teresinha; Conran, Nicola; Costa, Fernando Ferreira

2013-11-01

The endothelium plays an important role in sickle cell anemia (SCA) pathophysiology, interacting with red cells, leukocytes and platelets during the vaso-occlusive process and undergoing activation and dysfunction as a result of intravascular hemolysis and chronic inflammation. Blood outgrowth endothelial cells (BOECs) can be isolated from adult peripheral blood and have been used in diverse studies, since they have a high proliferative capacity and a stable phenotype during in vitro culture. This study aimed to establish BOEC cultures for use as an in vitro study model for endothelial function in sickle cell anemia. Once established, BOECs from steady-state SCA individuals (SCA BOECs) were characterized for their adhesive and inflammatory properties, in comparison to BOECs from healthy control individuals (CON BOECs). Cell adhesion assays demonstrated that control individual red cells adhered significantly more to SCA BOEC than to CON BOEC. Despite these increased adhesive properties, SCA BOECs did not demonstrate significant differences in their expression of major endothelial adhesion molecules, compared to CON BOECs. SCA BOECs were also found to be pro-inflammatory, producing a significantly higher quantity of the cytokine, IL-8, than CON BOECs. From the results obtained, we suggest that BOEC may be a good model for the in vitro study of SCA. Data indicate that endothelial cells of sickle cell anemia patients may have abnormal inflammatory and adhesive properties even outside of the chronic inflammatory and vaso-occlusive environment of patients. © 2013.

Age-Related Cognitive Impairments in Mice with a Conditional Ablation of the Neural Cell Adhesion Molecule

ERIC Educational Resources Information Center

Bisaz, Reto; Boadas-Vaello, Pere; Genoux, David; Sandi, Carmen

2013-01-01

Most of the mechanisms involved in neural plasticity support cognition, and aging has a considerable effect on some of these processes. The neural cell adhesion molecule (NCAM) of the immunoglobulin superfamily plays a pivotal role in structural and functional plasticity and is required to modulate cognitive and emotional behaviors. However,…

Bacterial adhesion force quantification by fluidic force microscopy

NASA Astrophysics Data System (ADS)

Potthoff, Eva; Ossola, Dario; Zambelli, Tomaso; Vorholt, Julia A.

2015-02-01

Quantification of detachment forces between bacteria and substrates facilitates the understanding of the bacterial adhesion process that affects cell physiology and survival. Here, we present a method that allows for serial, single bacterial cell force spectroscopy by combining the force control of atomic force microscopy with microfluidics. Reversible bacterial cell immobilization under physiological conditions on the pyramidal tip of a microchanneled cantilever is achieved by underpressure. Using the fluidic force microscopy technology (FluidFM), we achieve immobilization forces greater than those of state-of-the-art cell-cantilever binding as demonstrated by the detachment of Escherichia coli from polydopamine with recorded forces between 4 and 8 nN for many cells. The contact time and setpoint dependence of the adhesion forces of E. coli and Streptococcus pyogenes, as well as the sequential detachment of bacteria out of a chain, are shown, revealing distinct force patterns in the detachment curves. This study demonstrates the potential of the FluidFM technology for quantitative bacterial adhesion measurements of cell-substrate and cell-cell interactions that are relevant in biofilms and infection biology.Quantification of detachment forces between bacteria and substrates facilitates the understanding of the bacterial adhesion process that affects cell physiology and survival. Here, we present a method that allows for serial, single bacterial cell force spectroscopy by combining the force control of atomic force microscopy with microfluidics. Reversible bacterial cell immobilization under physiological conditions on the pyramidal tip of a microchanneled cantilever is achieved by underpressure. Using the fluidic force microscopy technology (FluidFM), we achieve immobilization forces greater than those of state-of-the-art cell-cantilever binding as demonstrated by the detachment of Escherichia coli from polydopamine with recorded forces between 4 and 8 nN for many cells. The contact time and setpoint dependence of the adhesion forces of E. coli and Streptococcus pyogenes, as well as the sequential detachment of bacteria out of a chain, are shown, revealing distinct force patterns in the detachment curves. This study demonstrates the potential of the FluidFM technology for quantitative bacterial adhesion measurements of cell-substrate and cell-cell interactions that are relevant in biofilms and infection biology. Electronic supplementary information (ESI) available: Video S1. Detachment of a S. pyogenes cell chain from glass substrate. The cantilever is approached on the outermost adherent cell of a chain and four bacteria were then sequentially detached. The sequential cell detachment suddenly stopped after four bacteria. This possibly occurred because bacteria-glass interactions became too strong or the maximal probe retraction was reached. The cells spontaneously detached from the cantilever flipping back on the surface. Fig. S1. (A) Adhesion force-distance and (B) adhesion force-detaching work correlation of E.coli on PLL for setpoints of 1 and 10 nN. Circle: 1 nN setpoint, square: 10 nN. See DOI: 10.1039/c4nr06495j

Kinetics of Pseudomonas aeruginosa adhesion to 304 and 316-L stainless steel: role of cell surface hydrophobicity.

PubMed Central

Vanhaecke, E; Remon, J P; Moors, M; Raes, F; De Rudder, D; Van Peteghem, A

1990-01-01

Fifteen different isolates of Pseudomonas aeruginosa were used to study the kinetics of adhesion to 304 and 316-L stainless steel. Stainless steel plates were incubated with approximately 1.5 X 10(7) CFU/ml in 0.01 M phosphate-buffered saline (pH 7.4). After the plates were rinsed with the buffer, the number of adhering bacteria was determined by a bioluminescence assay. Measurable adhesion, even to the electropolished surfaces, occurred within 30 s. Bacterial cell surface hydrophobicity, as determined by the bacterial adherence to hydrocarbons test and the contact angle measurement test, was the major parameter influencing the adhesion rate constant for the first 30 min of adhesion. A parabolic relationship between the CAM values and the logarithm of the adhesion rate constants (In k) was established. No correlation between either the salt aggregation or the improved salt aggregation values and the bacterial adhesion rate constants could be found. Since there was no significant correlation between the bacterial electrophoretic mobilities and the In k values, the bacterial cell surface charge seemed of minor importance in the process of adhesion of P. aeruginosa to 304 and 316-L stainless steel. PMID:2107796

Connective tissue growth factor is a positive regulator of epithelial-mesenchymal transition and promotes the adhesion with gastric cancer cells in human peritoneal mesothelial cells.

PubMed

Jiang, Cheng-Gang; Lv, Ling; Liu, Fu-Rong; Wang, Zhen-Ning; Na, Di; Li, Feng; Li, Jia-Bin; Sun, Zhe; Xu, Hui-Mian

2013-01-01

Connective tissue growth factor (CTGF) is involved in human cancer development and progression. Epithelial to mesenchymal transition (EMT) plays an important role in many biological processes. In this study, we wished to investigate the role of CTGF in EMT of peritoneal mesothelial cells and the effects of CTGF on adhesion of gastric cancer cells to mesothelial cells. Human peritoneal mesothelial cells (HPMCs) were cultured with TGF-β1 or various concentrations of CTGF for different time. The EMT process was monitored by morphology. Real-time RT-PCR and Western blot were used to evaluate the expression of vimentin, α-SMA , E-cadherin and β-catenin. RNA interference was used to achieve selective and specific knockdown of CTGF. We demonstrated that CTGF induced EMT of mesothelial cells in a dose- and time-dependent manner. HPMCs were exposed to TGF-β1 also underwent EMT which was associated with the induction of CTGF expression. Transfection with CTGF siRNA was able to reverse the EMT partially after treatment of TGF-β1. Moreover, the induced EMT of HPMCs was associated with an increased adhesion of gastric cancer cells to mesothelial cells. These findings suggest that CTGF is not only an important mediator but a potent activator of EMT in peritoneal mesothelial cells, which in turn promotes gastric cancer cell adhesion to peritoneum. Copyright © 2012 Elsevier Ltd. All rights reserved.

Phosphorylation of paxillin via the ERK mitogen-activated protein kinase cascade in EL4 thymoma cells.

PubMed

Ku, H; Meier, K E

2000-04-14

Intracellular signals can regulate cell adhesion via several mechanisms in a process referred to as "inside-out" signaling. In phorbol ester-sensitive EL4 thymoma cells, phorbol-12-myristate 13-acetate (PMA) induces activation of extracellular signal-regulated kinase (ERK) mitogen-activated protein kinases and promotes cell adhesion. In this study, clonal EL4 cell lines with varying abilities to activate ERKs in response to PMA were used to examine signaling events occurring downstream of ERK activation. Paxillin, a multifunctional docking protein involved in cell adhesion, was phosphorylated on serine/threonine residues in response to PMA treatment. This response was correlated with the extent and time course of ERK activation. PMA-induced phosphorylation of paxillin was inhibited by compounds that block the ERK activation pathway in EL4 cells, primary murine thymocytes, and primary murine splenocytes. Paxillin was phosphorylated in vitro by purified active ERK2. Two-dimensional electrophoresis revealed that PMA treatment generated a complex pattern of phosphorylated paxillin species in intact cells, some of which were generated by ERK-mediated phosphorylation in vitro. An ERK pathway inhibitor interfered with PMA-induced adhesion of sensitive EL4 cells to substrate. These findings describe a novel inside-out signaling pathway by which the ERK cascade may regulate events involved in adhesion.

Colorectal Cancer Metastases Settle in the Hepatic Microenvironment Through α5β1 Integrin.

PubMed

Pelillo, Chiara; Bergamo, Alberta; Mollica, Hilaria; Bestagno, Marco; Sava, Gianni

2015-10-01

Colorectal cancer (CRC) metastasis dissemination to secondary sites represents the critical point for the patient's survival. The microenvironment is crucial to cancer progression, influencing tumour cell behaviour by modulating the expression and activation of molecules such as integrins, the cell-extracellular matrix interacting proteins participating in different steps of the tumour metastatic process. In this work, we investigated the role of α5β1 integrin and how the microenvironment influences this adhesion molecule, in a model of colon cancer progression to the liver. The culture medium conditioned by the IHH hepatic cell line, and the extracellular matrix (ECM) proteins, modulate the activation of α5β1 integrin in the colon cancer cell line HCT-116, and drives FAK phosphorylation during the process of cell adhesion to fibronectin, one of the main components of liver ECM. In these conditions, α5β1 modulates the expression/activity of another integrin, α2β1, involved in the cell adhesion to collagen I. These results suggest that α5β1 integrin holds a leading role in HCT-116 colorectal cancer cells adhesion to the ECM through the modulation of the intracellular focal adhesion kinase FAK and the α2β1 integrin activity. The driving role of the tumour microenvironment on CRC dissemination, here detected, and described, strengthens and adds new value to the concept that α5β1 integrin can be an appropriate and relevant therapeutic target for the control of CRC metastases. © 2015 Wiley Periodicals, Inc.

Cell-matrix interactions of Entamoeba histolytica and E. dispar. A comparative study by electron-, atomic force- and confocal microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Talamás-Lara, Daniel, E-mail: daniel_talamas@hotmail.com; Talamás-Rohana, Patricia, E-mail: ptr@cinvestav.mx; Fragoso-Soriano, Rogelio Jaime, E-mail: rogelio@fis.cinvestav.mx

Invasion of tissues by Entamoeba histolytica is a multistep process that initiates with the adhesion of the parasite to target tissues. The recognition of the non-invasive Entamoeba dispar as a distinct, but closely related protozoan species raised the question as to whether the lack of its pathogenic potential could be related to a weaker adhesion due to limited cytoskeleton restructuring capacity. We here compared the adhesion process of both amebas to fibronectin through scanning, transmission, atomic force, and confocal microscopy. In addition, electrophoretic and western blot assays of actin were also compared. Adhesion of E. histolytica to fibronectin involves amore » dramatic reorganization of the actin network that results in a tighter contact to and the subsequent focal degradation of the fibronectin matrix. In contrast, E. dispar showed no regions of focal adhesion, the cytoskeleton was poorly reorganized and there was little fibronectin degradation. In addition, atomic force microscopy using topographic, error signal and phase modes revealed clear-cut differences at the site of contact of both amebas with the substrate. In spite of the morphological and genetic similarities between E. histolytica and E. dispar the present results demonstrate striking differences in their respective cell-to-matrix adhesion processes, which may be of relevance for understanding the invasive character of E. histolytica. - Highlights: • Striking differences in adhesion to FN between E. histolytica and E. dispar. • A greater degree of cell stiffness in E. histolytica with respect to E. dispar. • E. histolytica but not E. dispar forms regions of close contact with FN. • The actin cytoskeleton is involved in the pathogenicity of E. histolytica.« less

Actin dynamics at focal adhesions: a common endpoint and putative therapeutic target for proteinuric kidney diseases.

PubMed

Sever, Sanja; Schiffer, Mario

2018-06-01

Proteinuria encompasses diverse causes including both genetic diseases and acquired forms such as diabetic and hypertensive nephropathy. The basis of proteinuria is a disturbance in size selectivity of the glomerular filtration barrier, which largely depends on the podocyte: a terminally differentiated epithelial cell type covering the outer surface of the glomerulus. Compromised podocyte structure is one of the earliest signs of glomerular injury. The phenotype of diverse animal models and podocyte cell culture firmly established the essential role of the actin cytoskeleton in maintaining functional podocyte structure. Podocyte foot processes, actin-based membrane extensions, contain 2 molecularly distinct "hubs" that control actin dynamics: a slit diaphragm and focal adhesions. Although loss of foot processes encompasses disassembly of slit diaphragm multiprotein complexes, as long as cells are attached to the glomerular basement membrane, focal adhesions will be the sites in which stress due to filtration flow is counteracted by forces generated by the actin network in foot processes. Numerous studies within last 20 years have identified actin binding and regulatory proteins as well as integrins as essential components of signaling and actin dynamics at focal adhesions in podocytes, suggesting that some of them may become novel, druggable targets for proteinuric kidney diseases. Here we review evidence supporting the idea that current treatments for chronic kidney diseases beneficially and directly target the podocyte actin cytoskeleton associated with focal adhesions and suggest that therapeutic reagents that target the focal adhesion-regulated actin cytoskeleton in foot processes have potential to modernize treatments for chronic kidney diseases. Copyright © 2018 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

Selective binding and lateral clustering of α5β1 and αvβ3 integrins: Unraveling the spatial requirements for cell spreading and focal adhesion assembly

PubMed Central

Schaufler, Viktoria; Czichos-Medda, Helmi; Hirschfeld-Warnecken, Vera; Neubauer, Stefanie; Rechenmacher, Florian; Medda, Rebecca; Kessler, Horst; Geiger, Benjamin; Spatz, Joachim P.; Cavalcanti-Adam, E. Ada

2016-01-01

ABSTRACT Coordination of the specific functions of α5β1 and αvβ3 integrins is crucial for the precise regulation of cell adhesion, spreading and migration, yet the contribution of differential integrin-specific crosstalk to these processes remains unclear. To determine the specific functions of αvβ3 and α5β1 integrins, we used nanoarrays of gold particles presenting immobilized, integrin-selective peptidomimetic ligands. Integrin binding to the peptidomimetics is highly selective, and cells can spread on both ligands. However, spreading is faster and the projected cell area is greater on α5β1 ligand; both depend on ligand spacing. Quantitative analysis of adhesion plaques shows that focal adhesion size is increased in cells adhering to αvβ3 ligand at 30 and 60 nm spacings. Analysis of αvβ3 and α5β1 integrin clusters indicates that fibrillar adhesions are more prominent in cells adhering to α5β1 ligand, while clusters are mostly localized at the cell margins in cells adhering to αvβ3 ligand. αvβ3 integrin clusters are more pronounced on αvβ3 ligand, though they can also be detected in cells adhering to α5β1 ligand. Furthermore, α5β1 integrin clusters are present in cells adhering to α5β1 ligand, and often colocalize with αvβ3 clusters. Taken together, these findings indicate that the activation of αvβ3 integrin by ligand binding is dispensable for initial adhesion and spreading, but essential to formation of stable focal adhesions. PMID:27003228

The first EGF domain of coagulation factor IX attenuates cell adhesion and induces apoptosis.

PubMed

Ishikawa, Tomomi; Kitano, Hisataka; Mamiya, Atsushi; Kokubun, Shinichiro; Hidai, Chiaki

2016-07-01

Coagulation factor IX (FIX) is an essential plasma protein for blood coagulation. The first epidermal growth factor (EGF) motif of FIX (EGF-F9) has been reported to attenuate cell adhesion to the extracellular matrix (ECM). The purpose of the present study was to determine the effects of this motif on cell adhesion and apoptosis. Treatment with a recombinant EGF-F9 attenuated cell adhesion to the ECM within 10 min. De-adhesion assays with native FIX recombinant FIX deletion mutant proteins suggested that the de-adhesion activity of EGF-F9 requires the same process of FIX activation as that which occurs for coagulation activity. The recombinant EGF-F9 increased lactate dehydrogenase (LDH) activity release into the medium and increased the number of cells stained with annexin V and activated caspase-3, by 8.8- and 2.7-fold respectively, indicating that EGF-F9 induced apoptosis. Activated caspase-3 increased very rapidly after only 5 min of administration of recombinant EGF-F9. Treatment with EGF-F9 increased the level of phosphorylated p38 mitogen-activated protein kinase (MAPK), but not that of phosphorylated MAPK 44/42 or c-Jun N-terminal kinase (JNK). Inhibitors of caspase-3 suppressed the release of LDH. Caspase-3 inhibitors also suppressed the attenuation of cell adhesion and phosphorylation of p38 MAPK by EGF-F9. Our data indicated that EGF-F9 activated signals for apoptosis and induced de-adhesion in a caspase-3 dependent manner. © 2016 The Author(s).

Expression of Inflammation-related Intercellular Adhesion Molecules in Cardiomyocytes In Vitro and Modulation by Pro-inflammatory Agents.

PubMed

El-Battrawy, Ibrahim; Tülümen, Erol; Lang, Siegfried; Akin, Ibrahim; Behnes, Michael; Zhou, Xiabo; Mavany, Martin; Bugert, Peter; Bieback, Karen; Borggrefe, Martin; Elmas, Elif

2016-01-01

Cell-surface adhesion molecules regulate multiple intercellular and intracellular processes and play important roles in inflammation by facilitating leukocyte endothelial transmigration. Whether cardiomyocytes express surface-adhesion molecules related to inflammation and the effect of pro-inflammatory mediators remain unknown. In the present study, the expression of different cell-adhesion molecules (CD11a, CD11b, CD31, CD62P, CD162, F11 receptor and mucosal vascular addressin cell adhesion molecule 1 (MADCAM1)) and the effect of pro-inflammatory mediators were investigated in an in vitro model of human cardiomyocytes. Cells were supplied as a primary culture of cardiac alpha actin-positive cells from human heart tissue. The cells were incubated for 24 h with 1 U/ml thrombin or 700 ng/ml lipopolysaccharide (LPS) or with a combination of both. The expression of the cell adhesion molecules was measured by flow cytometry. In cultured human cardiomyocytes, 22.8% of cells expressed CD31, 7.1% MADCAM1 and 2.6% F11R. CD11a, CD11b, CD62P and CD162 were expressed by fewer than 2% of the cells at baseline. CD31 expression increased on incubation of cardiomyocytes with thrombin by 26% (p<0.05) and with LPS by 26% (p=0.06). The combination of thrombin and LPS did not result in increased levels of CD31 (p>0.10). The pro-inflammatory agents LPS and thrombin had no effect on the expression of MADCAM1 and F11R. Inflammation-related cell-adhesion molecules CD31, MADCAM1 and F11R were shown to be expressed on the surface of human cardiomyocytes in an in vitro model. Incubation with LPS or thrombin resulted in increased expression of CD31, however, it did not modify the expression of the cell adhesion molecules MADCAM1 and F11R. Copyright © 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Noncanonical roles of membranous lysyl-tRNA synthetase in transducing cell-substrate signaling for invasive dissemination of colon cancer spheroids in 3D collagen I gels

PubMed Central

Nam, Seo Hee; Kim, Doyeun; Lee, Mi-Sook; Lee, Doohyung; Kwak, Tae Kyoung; Kang, Minkyung; Ryu, Jihye; Kim, Hye-Jin; Song, Haeng Eun; Choi, Jungeun; Lee, Gyu-Ho; Kim, Sang-Yeob; Park, Song Hwa; Kim, Dae Gyu; Kwon, Nam Hoon; Kim, Tai Young; Thiery, Jean Paul; Kim, Sunghoon; Lee, Jung Weon

2015-01-01

The adhesion properties of cells are involved in tumor metastasis. Although KRS at the plasma membrane is shown important for cancer metastasis, additionally to canonical roles of cytosolic KRS in protein translation, how KRS and its downstream effectors promote the metastatic migration remains unexplored. Disseminative behaviors (an earlier metastatic process) of colon cancer cell spheroids embedded in 3D collagen gels were studied with regards to cell adhesion properties, and relevance in KRS−/+ knocked-down animal and clinical colon cancer tissues. Time-lapse imaging revealed KRS-dependent cell dissemination from the spheroids, whereas KRS-suppressed spheroids remained static due to the absence of outbound movements supported by cell-extracellular matrix (ECM) adhesion. While keeping E-cadherin at the outward disseminative cells, KRS caused integrin-involved intracellular signaling for ERK/c-Jun, paxillin, and cell-ECM adhesion-mediated signaling to modulate traction force for crawling movement. KRS-suppressed spheroids became disseminative following ERK or paxillin re-expression. The KRS-dependent intracellular signaling activities correlated with the invasiveness in clinical colon tumor tissues and in KRS−/+ knocked-down mice tissues. Collectively, these observations indicate that KRS at the plasma membrane plays new roles in metastatic migration as a signaling inducer, and causes intracellular signaling for cancer dissemination, involving cell-cell and cell-ECM adhesion, during KRS-mediated metastasis. PMID:26091349

Low-level laser irradiation modifies the effect of hyperglycemia on adhesion molecule levels.

PubMed

Góralczyk, Krzysztof; Szymańska, Justyna; Gryko, Łukasz; Fisz, Jacek; Rość, Danuta

2018-05-03

Endothelium plays a key role in maintaining vascular homeostasis by secreting active factors involved in many biological processes such as hemostasis, angiogenesis, and inflammation. Hyperglycemia in diabetic patients causes dysfunction of endothelial cells. Soluble fractions of adhesion molecules like sE-selectin and vascular cell adhesion molecule (sVCAM) are considered as markers of endothelial damage. The low-level laser therapy (LLLT) effectively supports the conventional treatment of vascular complications in diabetes, for example hard-to-heal wounds in patients with diabetic foot syndrome. The aim of our study was to evaluate the effect of low-energy laser at the wavelength of 635 nm (visible light) and 830 nm (infrared) on the concentration of adhesion molecules: sE-selectin and sVCAM in the supernatant of endothelial cell culture of HUVEC line. Cells were cultured under high-glucose conditions of 30 mM/L. We have found an increase in sE-selectin and sVCAM levels in the supernatant of cells cultured under hyperglycemic conditions. This fact confirms detrimental influence of hyperglycemia on vascular endothelial cell cultures. LLLT can modulate the inflammation process. It leads to a decrease in sE-selectin and sVCAM concentration in the supernatant and an increase in the number of endothelial cells cultured under hyperglycemic conditions. The influence of LLLT is greater at the wavelength of 830 nm.

Optimising parameters for the differentiation of SH-SY5Y cells to study cell adhesion and cell migration.

PubMed

Dwane, Susan; Durack, Edel; Kiely, Patrick A

2013-09-11

Cell migration is a fundamental biological process and has an important role in the developing brain by regulating a highly specific pattern of connections between nerve cells. Cell migration is required for axonal guidance and neurite outgrowth and involves a series of highly co-ordinated and overlapping signalling pathways. The non-receptor tyrosine kinase, Focal Adhesion Kinase (FAK) has an essential role in development and is the most highly expressed kinase in the developing CNS. FAK activity is essential for neuronal cell adhesion and migration. The objective of this study was to optimise a protocol for the differentiation of the neuroblastoma cell line, SH-SY5Y. We determined the optimal extracellular matrix proteins and growth factor combinations required for the optimal differentiation of SH-SY5Y cells into neuronal-like cells and determined those conditions that induce the expression of FAK. It was confirmed that the cells were morphologically and biochemically differentiated when compared to undifferentiated cells. This is in direct contrast to commonly used differentiation methods that induce morphological differentiation but not biochemical differentiation. We conclude that we have optimised a protocol for the differentiation of SH-SY5Y cells that results in a cell population that is both morphologically and biochemically distinct from undifferentiated SH-SY5Y cells and has a distinct adhesion and spreading pattern and display extensive neurite outgrowth. This protocol will provide a neuronal model system for studying FAK activity during cell adhesion and migration events.

The glycocalyx promotes cooperative binding and clustering of adhesion receptors.

PubMed

Xu, Guang-Kui; Qian, Jin; Hu, Jinglei

2016-05-18

Cell adhesion plays a pivotal role in various biological processes, e.g., immune responses, cancer metastasis, and stem cell differentiation. The adhesion behaviors depend subtly on the binding kinetics of receptors and ligands restricted at the cell-substrate interfaces. Although much effort has been directed toward investigating the kinetics of adhesion molecules, the role of the glycocalyx, anchored on cell surfaces as an exterior layer, is still unclear. In this paper, we propose a theoretical approach to study the collective binding kinetics of a few and a large number of binders in the presence of the glycocalyx, representing the cases of initial and mature adhesions of cells, respectively. The analytical results are validated by finding good agreement with our Monte Carlo simulations. In the force loading case, the on-rate and affinity increase as more bonds form, whereas this cooperative effect is not observed in the displacement loading case. The increased thickness and stiffness of the glycocalyx tend to decrease the affinity for a few bonds, while they have less influence on the affinity for a large number of bonds. Moreover, for a flexible membrane with thermally-excited shape fluctuations, the glycocalyx is exhibited to promote the formation of bond clusters, mainly due to the cooperative binding of binders. This study helps to understand the cooperative kinetics of adhesion receptors under physiologically relevant loading conditions and sheds light on the novel role of the glycocalyx in cell adhesion.

Mapping the Dynamics of Shear Stress—Induced Structural Changes in Endothelial Cells

PubMed Central

Mott, Rosalind E.; Helmke, Brian P.

2009-01-01

Hemodynamic shear stress regulates endothelial cell biochemical processes that govern cytoskeletal contractility, focal adhesion dynamics, and extracellular matrix assembly. Since shear stress causes rapid strain focusing at discrete locations in the cytoskeleton, we hypothesized that shear stress coordinately alters structural dynamics in the cytoskeleton, focal adhesion sites, and extracellular matrix on a time scale of minutes. Using multi-wavelength 4-D fluorescence microscopy, we measured the displacement of rhodamine-fibronectin and of GFP-labeled actin, vimentin, paxillin, and/or vinculin in aortic endothelial cells before and after onset of steady unidirectional shear stress. In the cytoskeleton, the onset of shear stress increased actin polymerization into lamellipodia, altered the angle of lateral displacement of actin stress fibers and vimentin filaments, and decreased centripetal remodeling of actin stress fibers in both subconfluent and confluent cell layers. Shear stress induced the formation of new focal complexes and reduced the centripetal remodeling of focal adhesions in regions of new actin polymerization. The structural dynamics of focal adhesions and the fibronectin matrix varied with cell density. In subconfluent cell layers, shear stress onset decreased the displacement of focal adhesions and fibronectin fibrils. In confluent monolayers, the direction of fibronectin and focal adhesion displacement shifted significantly towards the downstream direction within one minute after onset of shear stress. These spatially coordinated rapid changes in the structural dynamics of cytoskeleton, focal adhesions, and extracellular matrix are consistent with focusing of mechanical stress and/or strain near major sites of shear stress-mediated mechanotransduction. PMID:17855768

Development of an all-metal thick film cost affective metallization system for solar cells

NASA Technical Reports Server (NTRS)

Ross, B.

1981-01-01

An economical thick film solar cell contact for high volume production of low cost silicon solar array modules was investigated. All metal screenable pastes using base metals were studied. Solar cells with junction depths varying by a factor of 3.3, with and without a deposited oxide coating were used. Cells were screened and fired by a two step firing process. Adhesion and metallurgical results are unsatisfactory. No electrical information is obtained due to inadequate contact adhesion.

The Role of Cell-Cell Adhesion in the Formation of Multicellular Sprouts

PubMed Central

Szabó, A.; Czirók, A.

2010-01-01

Collective cell motility and its guidance via cell-cell contacts is instrumental in several morphogenetic and pathological processes such as vasculogenesis or tumor growth. Multicellular sprout elongation, one of the simplest cases of collective motility, depends on a continuous supply of cells streaming along the sprout towards its tip. The phenomenon is often explained as leader cells pulling the rest of the sprout forward via cell-cell adhesion. Building on an empirically demonstrated analogy between surface tension and cell-cell adhesion, we demonstrate that such a mechanism is unable to recruit cells to the sprout. Moreover, the expansion of such hypothetical sprouts is limited by a form of the Plateau-Taylor instability. In contrast, actively moving cells – guided by cell-cell contacts – can readily populate and expand linear sprouts. We argue that preferential attraction to the surfaces of elongated cells can provide a generic mechanism, shared by several cell types, for multicellular sprout formation. PMID:20165554

Long ligands reinforce biological adhesion under shear flow

NASA Astrophysics Data System (ADS)

Belyaev, Aleksey V.

2018-04-01

In this work, computer modeling has been used to show that longer ligands allow biological cells (e.g., blood platelets) to withstand stronger flows after their adhesion to solid walls. A mechanistic model of polymer-mediated ligand-receptor adhesion between a microparticle (cell) and a flat wall has been developed. The theoretical threshold between adherent and non-adherent regimes has been derived analytically and confirmed by simulations. These results lead to a deeper understanding of numerous biophysical processes, e.g., arterial thrombosis, and to the design of new biomimetic colloid-polymer systems.

ETV5 transcription factor is overexpressed in ovarian cancer and regulates cell adhesion in ovarian cancer cells.

PubMed

Llauradó, Marta; Abal, Miguel; Castellví, Josep; Cabrera, Sílvia; Gil-Moreno, Antonio; Pérez-Benavente, Asumpció; Colás, Eva; Doll, Andreas; Dolcet, Xavier; Matias-Guiu, Xavier; Vazquez-Levin, Mónica; Reventós, Jaume; Ruiz, Anna

2012-04-01

Epithelial ovarian cancer is the most lethal gynecological malignancy and the fifth leading cause of cancer deaths in women in the Western world. ETS transcription factors are known to act as positive or negative regulators of the expression of genes that are involved in various biological processes, including those that control cellular proliferation, differentiation, apoptosis, tissue remodeling, angiogenesis and transformation. ETV5 belongs to the PEA3 subfamily. PEA3 subfamily members are able to activate the transcription of proteases, matrix metalloproteinases and tissue inhibitor of metalloproteases, which is central to both tumor invasion and angiogenesis. Here, we examined the role of the ETV5 transcription factor in epithelial ovarian cancer and we found ETV5 was upregulated in ovarian tumor samples compared to ovarian tissue controls. The in vitro inhibition of ETV5 decreased cell proliferation in serum-deprived conditions, induced EMT and cell migration and decreased cell adhesion to extracellular matrix components. ETV5 inhibition also decreased cell-cell adhesion and induced apoptosis in anchorage-independent conditions. Accordingly, upregulation of ETV5 induced the expression of cell adhesion molecules and enhanced cell survival in a spheroid model. Our findings suggest that the overexpression of ETV5 detected in ovarian cancer cells may contribute to ovarian tumor progression through the ability of ETV5 to enhance proliferation of ovarian cancer cells. In addition, upregulation of ETV5 would play a role in ovarian cancer cell dissemination and metastasis into the peritoneal cavity by protecting ovarian cancer cells from apoptosis and by increasing the adhesion of ovarian cancer cells to the peritoneal wall through the regulation of cell adhesion molecules. Copyright © 2011 UICC.

Myosin 1g Contributes to CD44 Adhesion Protein and Lipid Rafts Recycling and Controls CD44 Capping and Cell Migration in B Lymphocytes

PubMed Central

López-Ortega, Orestes; Santos-Argumedo, Leopoldo

2017-01-01

Cell migration and adhesion are critical for immune system function and involve many proteins, which must be continuously transported and recycled in the cell. Recycling of adhesion molecules requires the participation of several proteins, including actin, tubulin, and GTPases, and of membrane components such as sphingolipids and cholesterol. However, roles of actin motor proteins in adhesion molecule recycling are poorly understood. In this study, we identified myosin 1g as one of the important motor proteins that drives recycling of the adhesion protein CD44 in B lymphocytes. We demonstrate that the lack of Myo1g decreases the cell-surface levels of CD44 and of the lipid raft surrogate GM1. In cells depleted of Myo1g, the recycling of CD44 was delayed, the delay seems to be caused at the level of formation of recycling complex and entry into recycling endosomes. Moreover, a defective lipid raft recycling in Myo1g-deficient cells had an impact both on the capping of CD44 and on cell migration. Both processes required the transportation of lipid rafts to the cell surface to deliver signaling components. Furthermore, the extramembrane was essential for cell expansion and remodeling of the plasma membrane topology. Therefore, Myo1g is important during the recycling of lipid rafts to the membrane and to the accompanied proteins that regulate plasma membrane plasticity. Thus, Myosin 1g contributes to cell adhesion and cell migration through CD44 recycling in B lymphocytes. PMID:29321775

State diagram for adhesion dynamics of deformable capsules under shear flow.

PubMed

Luo, Zheng Yuan; Bai, Bo Feng

2016-08-17

Due to the significance of understanding the underlying mechanisms of cell adhesion in biological processes and cell capture in biomedical applications, we numerically investigate the adhesion dynamics of deformable capsules under shear flow by using a three-dimensional computational fluid dynamic model. This model is based on the coupling of the front tracking-finite element method for elastic mechanics of the capsule membrane and the adhesion kinetics simulation for adhesive interactions between capsules and functionalized surfaces. Using this model, three distinct adhesion dynamic states are predicted, such as detachment, rolling and firm-adhesion. Specifically, the effects of capsule deformability quantified by the capillary number on the transitions of these three dynamic states are investigated by developing an adhesion dynamic state diagram for the first time. At low capillary numbers (e.g. Ca < 0.0075), whole-capsule deformation confers the capsule a flattened bottom in contact with the functionalized surface, which hence promotes the rolling-to-firm-adhesion transition. It is consistent with the observations from previous studies that cell deformation promotes the adhesion of cells lying in the rolling regime. However, it is surprising to find that, at relatively high capillary numbers (e.g. 0.0075 < Ca < 0.0175), the effect of capsule deformability on its adhesion dynamics is far more complex than just promoting adhesion. High deformability of capsules makes their bottom take a concave shape with no adhesion bond formation in the middle. The appearance of this specific capsule shape inhibits the transitions of both rolling-to-firm-adhesion and detachment-to-rolling, and it means that capsule deformation no longer promotes the capsule adhesion. Besides, it is interesting to note that, when the capillary number exceeds a critical value (e.g. Ca = 0.0175), the rolling state no longer appears, since capsules exhibit large deviation from the spherical shape.

A set of simple cell processes is sufficient to model spiral cleavage.

PubMed

Brun-Usan, Miguel; Marín-Riera, Miquel; Grande, Cristina; Truchado-Garcia, Marta; Salazar-Ciudad, Isaac

2017-01-01

During cleavage, different cellular processes cause the zygote to become partitioned into a set of cells with a specific spatial arrangement. These processes include the orientation of cell division according to: an animal-vegetal gradient; the main axis (Hertwig's rule) of the cell; and the contact areas between cells or the perpendicularity between consecutive cell divisions (Sachs' rule). Cell adhesion and cortical rotation have also been proposed to be involved in spiral cleavage. We use a computational model of cell and tissue biomechanics to account for the different existing hypotheses about how the specific spatial arrangement of cells in spiral cleavage arises during development. Cell polarization by an animal-vegetal gradient, a bias to perpendicularity between consecutive cell divisions (Sachs' rule), cortical rotation and cell adhesion, when combined, reproduce the spiral cleavage, whereas other combinations of processes cannot. Specifically, cortical rotation is necessary at the 8-cell stage to direct all micromeres in the same direction. By varying the relative strength of these processes, we reproduce the spatial arrangement of cells in the blastulae of seven different invertebrate species. © 2017. Published by The Company of Biologists Ltd.

Ectodomain Shedding by ADAM17: Its Role in Neutrophil Recruitment and the Impairment of This Process during Sepsis.

PubMed

Mishra, Hemant K; Ma, Jing; Walcheck, Bruce

2017-01-01

Neutrophils are specialized at killing bacteria and are recruited from the blood in a rapid and robust manner during infection. A cascade of adhesion events direct their attachment to the vascular endothelium and migration into the underlying tissue. A disintegrin and metalloproteinase 17 (ADAM17) functions in the cell membrane of neutrophils and endothelial cells by cleaving its substrates, typically in a cis manner, at an extracellular site proximal to the cell membrane. This process is referred to as ectodomain shedding and it results in the downregulation of various adhesion molecules and receptors, and the release of immune regulating factors. ADAM17 sheddase activity is induced upon cell activation and rapidly modulates intravascular adhesion events in response to diverse environmental stimuli. During sepsis, an excessive systemic inflammatory response against infection, neutrophil migration becomes severely impaired. This involves ADAM17 as indicated by increased levels of its cleaved substrates in the blood of septic patients, and that ADAM17 inactivation improves neutrophil recruitment and bacterial clearance in animal models of sepsis. Excessive ADAM17 sheddase activity during sepsis thus appears to undermine in a direct and indirect manner the necessary balance between intravascular adhesion and de-adhesion events that regulate neutrophil migration into sites of infection. This review provides an overview of ADAM17 function and regulation and its potential contribution to neutrophil dysfunction during sepsis.

Plasma functionalization of polycarbonaturethane to improve endothelialization--Effect of shear stress as a critical factor for biocompatibility control.

PubMed

Lukas, Karin; Thomas, Ulrich; Gessner, André; Wehner, Daniel; Schmid, Thomas; Schmid, Christof; Lehle, Karla

2016-04-01

Medical devices made of polycarbonaturethane (PCU) combine excellent mechanical properties and little biological degradation, but restricted hemocompatibility. Modifications of PCU might reduce platelet adhesion and promote stable endothelialization. PCU was modified using gas plasma treatment, binding of hydrogels, and coupling of cell-active molecules (modified heparin, anti-thrombin III (ATIII), argatroban, fibronectin, laminin-nonapeptide, peptides with integrin-binding arginine-glycine-aspartic acid (RGD) motif). Biocompatibility was verified with static and dynamic cell culture techniques. Blinded analysis focused on improvement in endothelial cell (EC) adhesion/proliferation, anti-thrombogenicity, reproducible manufacturing process, and shear stress tolerance of ECs. EC adhesion and antithrombogenicity were achieved with 9/35 modifications. Additionally, 6/9 stimulated EC proliferation and 3/6 modification processes were highly reproducible for endothelialization. The latter modifications comprised immobilization of ATIII (A), polyethyleneglycole-diamine-hydrogel (E) and polyethylenimine-hydrogel connected with modified heparin (IH). Under sheer stress, only the IH modification improved EC adhesion within the graft. However, ECs did not arrange in flow direction and cell anchorage was restricted. Despite large variation in surface modification chemistry and improved EC adhesion under static culture conditions, additional introduction of shear stress foiled promising preliminary data. Therefore, biocompatibility testing required not only static tests but also usage of physiological conditions such as shear stress in the case of vascular grafts. © The Author(s) 2016.

Biophysical studies on calcium and carbohydrate binding to carbohydrate recognition domain of Gal/GalNAc lectin from Entamoeba histolytica: insights into host cell adhesion.

PubMed

Yadav, Rupali; Verma, Kuldeep; Chandra, Mintu; Mukherjee, Madhumita; Datta, Sunando

2016-09-01

Entamoeba histolytica, an enteric parasite expresses a Gal/GalNAc-specific lectin that contributes to its virulence by establishing adhesion to host cell. In this study, carbohydrate recognition domain of Hgl (EhCRD) was purified and biophysical studies were conducted to understand the thermodynamic basis of its binding to carbohydrate and Ca(++) Here, we show that carbohydrate recognition domain (CRD) of the lectin binds to calcium through DPN motif. To decipher the role of calcium in carbohydrate binding and host cell adhesion, biophysical and cell-based studies were carried out. We demonstrated that the presence of the cation neither change the affinity of the lectin for carbohydrates nor alters its conformation. Mutation of the calcium-binding motif in EhCRD resulted in complete loss of ability to bind calcium but retained its affinity for carbohydrates. Purified EhCRD significantly diminished adhesion of the amebic trophozoites to Chinese Hamster Ovary (CHO) cells as well as triggered red blood cell agglutination. The calcium-binding defective mutant abrogated amebic adhesion to CHO cells similar to the wild-type protein, but it failed to agglutinate RBCs suggesting a differential role of the cation in these two processes. This study provides the first molecular description of the role of calcium in Gal/GalNAc mediated host cell adhesion. © The Authors 2016. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.

An Analytical Model for Determining Two-Dimensional Receptor-Ligand Kinetics

PubMed Central

Cheung, Luthur Siu-Lun; Konstantopoulos, Konstantinos

2011-01-01

Cell-cell adhesive interactions play a pivotal role in major pathophysiological vascular processes, such as inflammation, infection, thrombosis, and cancer metastasis, and are regulated by hemodynamic forces generated by blood flow. Cell adhesion is mediated by the binding of receptors to ligands, which are both anchored on two-dimensional (2-D) membranes of apposing cells. Biophysical assays have been developed to determine the unstressed (no-force) 2-D affinity but fail to disclose its dependence on force. Here we develop an analytical model to estimate the 2-D kinetics of diverse receptor-ligand pairs as a function of force, including antibody-antigen, vascular selectin-ligand, and bacterial adhesin-ligand interactions. The model can account for multiple bond interactions necessary to mediate adhesion and resist detachment amid high hemodynamic forces. Using this model, we provide a generalized biophysical interpretation of the counterintuitive force-induced stabilization of cell rolling observed by a select subset of receptor-ligand pairs with specific intrinsic kinetic properties. This study enables us to understand how single-molecule and multibond biophysics modulate the macroscopic cell behavior in diverse pathophysiological processes. PMID:21575567

Regulating the migration of smooth muscle cells by a vertically distributed poly(2-hydroxyethyl methacrylate) gradient on polymer brushes covalently immobilized with RGD peptides.

PubMed

Wu, Sai; Du, Wang; Duan, Yiyuan; Zhang, Deteng; Liu, Yixiao; Wu, Bingbing; Zou, Xiaohui; Ouyang, Hongwei; Gao, Changyou

2018-05-30

The gradient localization of biological cues is of paramount importance to guide directional migration of cells. In this study, poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate)-block- poly(2-hydroxyethyl methacrylate) (P(HEMA-co-GMA)-b-PHEMA) brushes with a uniform underneath P(HEMA-co-GMA) layer and a gradient thickness of PHEMA blocks were prepared by using surface-initiated atom-transfer radical polymerization and a dynamically controlled polymerization process. The polymer chains were subsequently functionalized with the cell-adhesive arginine-glycine-aspartic acid (RGD) peptides by reaction with the glycidyl groups, and their structures and properties were characterized by X-ray photoelectron spectrometry (XPS), quartz crystal microbalance with dissipation (QCM-D) and air contact angle. Adhesion and migration processes of smooth muscle cells (SMCs) were then studied. Compared with those on the sufficiently exposed RGD surface, the cell adhesion and mobility were well maintained when the RGD peptides were localized at 18.9 nm depth, whereas the adhesion, spreading and migration rate of SMCs were significantly impaired when the RGD peptides were localized at a depth of 38.4 nm. On the RGD depth gradient surface, the SMCs exhibited preferential orientation and enhanced directional migration toward the direction of reduced thickness of the second PHEMA brushes. Half of the cells were oriented within ± 30° to the x-axis direction, and 72% of the cells moved directionally at the optimal conditions. Cell adhesion strength, arrangement of cytoskeleton, and gene and protein expression levels of adhesion-related proteins were studied to corroborate the mechanisms, demonstrating that the cell mobility is regulated by the complex and synergetic intracellular signals resulted from the difference in surface properties. Cell migration is of paramount importance for the processes of tissue repair and regeneration. So far, the gradient localization of biological cues perpendicular to the substrate, which is the usual case for the biological signaling molecules to locate in ECM in vivo, has been scarcely studied, and has not been used to guide the directional migration of cells. In this study, we prepare a depth gradient of RGD peptides along the polymer chains, which is used to guide the directional migration of SMCs after a second hydrophilic bock is prepared in a gradient manner. For the first time the directional migration of SMCs is achieved under the guidance of a depth gradient of RGD ligands. The mechanisms of different cell migration abilities are further discussed based on the results of cell adhesion, cell adhesion force, cytoskeleton alignment and expression of relative proteins and genes. This work paves a new strategy by fabricating a gradient polymer brushes with immobilized bioactive molecules to dominate the directional cell migration, and elucidates the mechanisms underlining the biased migration along RGD depth localization gradients, shedding a light for the design of novel biomaterials to control and guide cell migration and invasion. Copyright © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Specific Adhesion of Lipid Membranes Can Simultaneously Produce Two Types of Lipid and Protein Heterogeneities

NASA Astrophysics Data System (ADS)

Shindell, Orrin; Micah, Natalie; Ritzer, Max; Gordon, Vernita

2015-03-01

Living cells adhere to one another and their environment. Adhesion is associated with re-organization of the lipid and protein components of the cell membrane. The resulting heterogeneities are functional structures involved in biological processes. We use artificial lipid membranes that contain a single type of binding protein. Before adhesion, the lipid, protein, and dye components in the membrane are well-mixed and constitute a single disordered-liquid phase (Ld) . After adhesion, two distinct types of heterogeneities coexist in the adhesion zone: a central domain of ordered lipid phase that excludes both binding proteins and membrane dye, and a peripheral domain of disordered lipid phase that is densely packed with adhesion proteins and enriched in membrane dye relative to the non-adhered portion of the vesicle. Thus, we show that adhesion that is mediated by only one type of protein can organize the lipid and protein components of the membranes into heterogeneities that resemble those found in biology, for example the immune synapse.

Sundew adhesive: a naturally occurring hydrogel

PubMed Central

Huang, Yujian; Wang, Yongzhong; Sun, Leming; Agrawal, Richa; Zhang, Mingjun

2015-01-01

Bioadhesives have drawn increasing interest in recent years, owing to their eco-friendly, biocompatible and biodegradable nature. As a typical bioadhesive, sticky exudate observed on the stalked glands of sundew plants aids in the capture of insects and this viscoelastic adhesive has triggered extensive interests in revealing the implied adhesion mechanisms. Despite the significant progress that has been made, the structural traits of the sundew adhesive, especially the morphological characteristics in nanoscale, which may give rise to the viscous and elastic properties of this mucilage, remain unclear. Here, we show that the sundew adhesive is a naturally occurring hydrogel, consisting of nano-network architectures assembled with polysaccharides. The assembly process of the polysaccharides in this hydrogel is proposed to be driven by electrostatic interactions mediated with divalent cations. Negatively charged nanoparticles, with an average diameter of 231.9 ± 14.8 nm, are also obtained from this hydrogel and these nanoparticles are presumed to exert vital roles in the assembly of the nano-networks. Further characterization via atomic force microscopy indicates that the stretching deformation of the sundew adhesive is associated with the flexibility of its fibrous architectures. It is also observed that the adhesion strength of the sundew adhesive is susceptible to low temperatures. Both elasticity and adhesion strength of the sundew adhesive reduce in response to lowering the ambient temperature. The feasibility of applying sundew adhesive for tissue engineering is subsequently explored in this study. Results show that the fibrous scaffolds obtained from sundew adhesive are capable of increasing the adhesion of multiple types of cells, including fibroblast cells and smooth muscle cells, a property that results from the enhanced adsorption of serum proteins. In addition, in light of the weak cytotoxic activity exhibited by these scaffolds towards a variety of mammal cells, evidence is sufficient to propose that sundew adhesive is a promising nanomaterial worth further exploitation in the field of tissue engineering. PMID:25948615

Tissue cohesion and the mechanics of cell rearrangement.

PubMed

David, Robert; Luu, Olivia; Damm, Erich W; Wen, Jason W H; Nagel, Martina; Winklbauer, Rudolf

2014-10-01

Morphogenetic processes often involve the rapid rearrangement of cells held together by mutual adhesion. The dynamic nature of this adhesion endows tissues with liquid-like properties, such that large-scale shape changes appear as tissue flows. Generally, the resistance to flow (tissue viscosity) is expected to depend on the cohesion of a tissue (how strongly its cells adhere to each other), but the exact relationship between these parameters is not known. Here, we analyse the link between cohesion and viscosity to uncover basic mechanical principles of cell rearrangement. We show that for vertebrate and invertebrate tissues, viscosity varies in proportion to cohesion over a 200-fold range of values. We demonstrate that this proportionality is predicted by a cell-based model of tissue viscosity. To do so, we analyse cell adhesion in Xenopus embryonic tissues and determine a number of parameters, including tissue surface tension (as a measure of cohesion), cell contact fluctuation and cortical tension. In the tissues studied, the ratio of surface tension to viscosity, which has the dimension of a velocity, is 1.8 µm/min. This characteristic velocity reflects the rate of cell-cell boundary contraction during rearrangement, and sets a limit to rearrangement rates. Moreover, we propose that, in these tissues, cell movement is maximally efficient. Our approach to cell rearrangement mechanics links adhesion to the resistance of a tissue to plastic deformation, identifies the characteristic velocity of the process, and provides a basis for the comparison of tissues with mechanical properties that may vary by orders of magnitude. © 2014. Published by The Company of Biologists Ltd.

Listeria monocytogenes uses Listeria adhesion protein (LAP) to promote bacterial transepithelial translocation and induces expression of LAP receptor Hsp60.

PubMed

Burkholder, Kristin M; Bhunia, Arun K

2010-12-01

Listeria monocytogenes interaction with the intestinal epithelium is a key step in the infection process. We demonstrated that Listeria adhesion protein (LAP) promotes adhesion to intestinal epithelial cells and facilitates extraintestinal dissemination in vivo. The LAP receptor is a stress response protein, Hsp60, but the precise role for the LAP-Hsp60 interaction during Listeria infection is unknown. Here we investigated the influence of physiological stressors and Listeria infection on host Hsp60 expression and LAP-mediated bacterial adhesion, invasion, and transepithelial translocation in an enterocyte-like Caco-2 cell model. Stressors such as heat (41°C), tumor necrosis factor alpha (TNF-α) (100 U), and L. monocytogenes infection (10(4) to 10(6) CFU/ml) significantly (P < 0.05) increased plasma membrane and intracellular Hsp60 levels in Caco-2 cells and consequently enhanced LAP-mediated L. monocytogenes adhesion but not invasion of Caco-2 cells. In transepithelial translocation experiments, the wild type (WT) exhibited 2.7-fold more translocation through Caco-2 monolayers than a lap mutant, suggesting that LAP is involved in transepithelial translocation, potentially via a paracellular route. Short hairpin RNA (shRNA) suppression of Hsp60 in Caco-2 cells reduced WT adhesion and translocation 4.5- and 3-fold, respectively, while adhesion remained unchanged for the lap mutant. Conversely, overexpression of Hsp60 in Caco-2 cells enhanced WT adhesion and transepithelial translocation, but not those of the lap mutant. Furthermore, initial infection with a low dosage (10(6) CFU/ml) of L. monocytogenes increased plasma membrane and intracellular expression of Hsp60 significantly, which rendered Caco-2 cells more susceptible to subsequent LAP-mediated adhesion and translocation. These data provide insight into the role of LAP as a virulence factor during intestinal epithelial infection and pose new questions regarding the dynamics between the host stress response and pathogen infection.

Delineating the Tes Interaction Site in Zyxin and Studying Cellular Effects of Its Disruption.

PubMed

Hadzic, Ermin; Catillon, Marie; Halavatyi, Aliaksandr; Medves, Sandrine; Van Troys, Marleen; Moes, Michèle; Baird, Michelle A; Davidson, Michael W; Schaffner-Reckinger, Elisabeth; Ampe, Christophe; Friederich, Evelyne

2015-01-01

Focal adhesions are integrin-based structures that link the actin cytoskeleton and the extracellular matrix. They play an important role in various cellular functions such as cell signaling, cell motility and cell shape. To ensure and fine tune these different cellular functions, adhesions are regulated by a large number of proteins. The LIM domain protein zyxin localizes to focal adhesions where it participates in the regulation of the actin cytoskeleton. Because of its interactions with a variety of binding partners, zyxin has been proposed to act as a molecular scaffold. Here, we studied the interaction of zyxin with such a partner: Tes. Similar to zyxin, Tes harbors three highly conserved LIM domains of which the LIM1 domain directly interacts with zyxin. Using different zyxin variants in pull-down assays and ectopic recruitment experiments, we identified the Tes binding site in zyxin and showed that four highly conserved amino acids are crucial for its interaction with Tes. Based upon these findings, we used a zyxin mutant defective in Tes-binding to assess the functional consequences of abrogating the zyxin-Tes interaction in focal adhesions. Performing fluorescence recovery after photobleaching, we showed that zyxin recruits Tes to focal adhesions and modulates its turnover in these structures. However, we also provide evidence for zyxin-independent localization of Tes to focal adhesions. Zyxin increases focal adhesion numbers and reduces focal adhesion lifetimes, but does so independent of Tes. Quantitative analysis showed that the loss of interaction between zyxin and Tes affects the process of cell spreading. We conclude that zyxin influences focal adhesion dynamics, that it recruits Tes and that this interaction is functional in regulating cell spreading.

Delineating the Tes Interaction Site in Zyxin and Studying Cellular Effects of Its Disruption

PubMed Central

Hadzic, Ermin; Catillon, Marie; Halavatyi, Aliaksandr; Medves, Sandrine; Van Troys, Marleen; Moes, Michèle; Baird, Michelle A.; Davidson, Michael W.; Schaffner-Reckinger, Elisabeth; Ampe, Christophe; Friederich, Evelyne

2015-01-01

Focal adhesions are integrin-based structures that link the actin cytoskeleton and the extracellular matrix. They play an important role in various cellular functions such as cell signaling, cell motility and cell shape. To ensure and fine tune these different cellular functions, adhesions are regulated by a large number of proteins. The LIM domain protein zyxin localizes to focal adhesions where it participates in the regulation of the actin cytoskeleton. Because of its interactions with a variety of binding partners, zyxin has been proposed to act as a molecular scaffold. Here, we studied the interaction of zyxin with such a partner: Tes. Similar to zyxin, Tes harbors three highly conserved LIM domains of which the LIM1 domain directly interacts with zyxin. Using different zyxin variants in pull-down assays and ectopic recruitment experiments, we identified the Tes binding site in zyxin and showed that four highly conserved amino acids are crucial for its interaction with Tes. Based upon these findings, we used a zyxin mutant defective in Tes-binding to assess the functional consequences of abrogating the zyxin-Tes interaction in focal adhesions. Performing fluorescence recovery after photobleaching, we showed that zyxin recruits Tes to focal adhesions and modulates its turnover in these structures. However, we also provide evidence for zyxin-independent localization of Tes to focal adhesions. Zyxin increases focal adhesion numbers and reduces focal adhesion lifetimes, but does so independent of Tes. Quantitative analysis showed that the loss of interaction between zyxin and Tes affects the process of cell spreading. We conclude that zyxin influences focal adhesion dynamics, that it recruits Tes and that this interaction is functional in regulating cell spreading. PMID:26509500

Collisions of deformable cells lead to collective migration

DOE PAGES

Löber, Jakob; Ziebert, Falko; Aranson, Igor S.

2015-03-17

Collective migration of eukaryotic cells plays a fundamental role in tissue growth, wound healing and immune response. The motion, arising spontaneously or in response to chemical and mechanical stimuli, is also important for understanding life-threatening pathologies, such as cancer and metastasis formation. We present a phase-field model to describe the movement of many self-organized, interacting cells. The model takes into account the main mechanisms of cell motility – acto-myosin dynamics, as well as substrate-mediated and cell-cell adhesion. It predicts that collective cell migration emerges spontaneously as a result of inelastic collisions between neighboring cells: collisions lead to a mutual alignmentmore » of the cell velocities and to the formation of coherently-moving multi-cellular clusters. Small cell-to-cell adhesion, in turn, reduces the propensity for large-scale collective migration, while higher adhesion leads to the formation of moving bands. Our study provides valuable insight into biological processes associated with collective cell motility.« less

Collisions of deformable cells lead to collective migration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Löber, Jakob; Ziebert, Falko; Aranson, Igor S.

Collective migration of eukaryotic cells plays a fundamental role in tissue growth, wound healing and immune response. The motion, arising spontaneously or in response to chemical and mechanical stimuli, is also important for understanding life-threatening pathologies, such as cancer and metastasis formation. We present a phase-field model to describe the movement of many self-organized, interacting cells. The model takes into account the main mechanisms of cell motility – acto-myosin dynamics, as well as substrate-mediated and cell-cell adhesion. It predicts that collective cell migration emerges spontaneously as a result of inelastic collisions between neighboring cells: collisions lead to a mutual alignmentmore » of the cell velocities and to the formation of coherently-moving multi-cellular clusters. Small cell-to-cell adhesion, in turn, reduces the propensity for large-scale collective migration, while higher adhesion leads to the formation of moving bands. Our study provides valuable insight into biological processes associated with collective cell motility.« less

Downregulation of connective tissue growth factor by three-dimensional matrix enhances ovarian carcinoma cell invasion.

PubMed

Barbolina, Maria V; Adley, Brian P; Kelly, David L; Shepard, Jaclyn; Fought, Angela J; Scholtens, Denise; Penzes, Peter; Shea, Lonnie D; Stack, M Sharon

2009-08-15

Epithelial ovarian carcinoma (EOC) is a leading cause of death from gynecologic malignancies, due mainly to the prevalence of undetected metastatic disease. The process of cell invasion during intraperitoneal anchoring of metastatic lesions requires concerted regulation of many processes, including modulation of adhesion to the extracellular matrix and localized invasion. Exploratory cDNA microarray analysis of early response genes (altered after 4 hr of 3D collagen culture) coupled with confirmatory real-time reverse-transcriptase polymerase chain reaction, multiple 3D cell culture matrices, Western blot, immunostaining, adhesion, migration and invasion assays were used to identify modulators of adhesion pertinent to EOC progression and metastasis. cDNA microarray analysis indicated a dramatic downregulation of connective tissue growth factor (CTGF) in EOC cells placed in invasion- mimicking conditions (3D Type I collagen). Examination of human EOC specimens revealed that CTGF expression was absent in 46% of the tested samples (n = 41), but was present in 100% of normal ovarian epithelium samples (n = 7). Reduced CTGF expression occurs in many types of cells and may be a general phenomenon displayed by cells encountering a 3D environment. CTGF levels were inversely correlated with invasion such that downregulation of CTGF increased, while its upregulation reduced collagen invasion. Cells adhered preferentially to a surface comprised of both collagen I and CTGF relative to either component alone using alpha6beta1 and alpha3beta1 integrins. Together these data suggest that downregulation of CTGF in EOC cells may be important for cell invasion through modulation of cell-matrix adhesion.

Downregulation of Connective Tissue Growth Factor by Three-Dimensional Matrix Enhances Ovarian Carcinoma Cell Invasion

PubMed Central

Barbolina, Maria V.; Adley, Brian P.; Kelly, David L.; Shepard, Jaclyn; Fought, Angela J.; Scholtens, Denise; Penzes, Peter; Shea, Lonnie D.; Sharon Stack, M

2010-01-01

Epithelial ovarian carcinoma (EOC) is a leading cause of death from gynecologic malignancy, due mainly to the prevalence of undetected metastatic disease. The process of cell invasion during intra-peritoneal anchoring of metastatic lesions requires concerted regulation of many processes, including modulation of adhesion to the extracellular matrix and localized invasion. Exploratory cDNA microarray analysis of early response genes (altered after 4 hours of 3-dimensional collagen culture) coupled with confirmatory real-time RT-PCR, multiple three-dimensional cell culture matrices, Western blot, immunostaining, adhesion, migration, and invasion assays were used to identify modulators of adhesion pertinent to EOC progression and metastasis. cDNA microarray analysis indicated a dramatic downregulation of connective tissue growth factor (CTGF) in EOC cells placed in invasion-mimicking conditions (3-dimensional type I collagen). Examination of human EOC specimens revealed that CTGF expression was absent in 46% of the tested samples (n=41), but was present in 100% of normal ovarian epithelium samples (n=7). Reduced CTGF expression occurs in many types of cells and may be a general phenomenon displayed by cells encountering a 3D environment. CTGF levels were inversely correlated with invasion such that downregulation of CTGF increased, while its upregulation reduced, collagen invasion. Cells adhered preferentially to a surface comprised of both collagen I and CTGF relative to either component alone using α6β1 and α3β1 integrins. Together these data suggest that downregulation of CTGF in EOC cells may be important for cell invasion through modulation of cell-matrix adhesion. PMID:19382180

Quantifying cell adhesion through impingement of a controlled microjet.

PubMed

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

2015-01-06

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/m(2)). 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) × 10(9) cells/m(2), 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. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Motile membrane protrusions regulate cell-cell adhesion and migration of olfactory ensheathing glia.

PubMed

Windus, Louisa C E; Claxton, Christina; Allen, Chelsea L; Key, Brian; St John, James A

2007-12-01

Olfactory ensheathing cells (OECs) are candidates for therapeutic approaches for neural regeneration due to their ability to assist axon regrowth in central nervous system lesion models. However, little is understood about the processes and mechanisms underlying migration of these cells. We report here that novel lamellipodial protrusions, termed lamellipodial waves, are integral to OEC migration. Time-lapse imaging of migrating OECs revealed that these highly dynamic waves progress along the shaft of the cells and are crucial for mediating cell-cell adhesion. Without these waves, cell-cell adhesion does not occur and migrational rates decline. The activity of waves is modulated by both glial cell line-derived neurotrophic factor and inhibitors of the JNK and SRC kinases. Furthermore, the activity of lamellipodial waves can be modulated by Mek1, independently of leading edge activity. The ability to selectively regulate cell migration via lamellipodial waves has implications for manipulating the migratory behavior of OECs during neural repair. (c) 2007 Wiley-Liss, Inc.

Optimising parameters for the differentiation of SH-SY5Y cells to study cell adhesion and cell migration

PubMed Central

2013-01-01

Background Cell migration is a fundamental biological process and has an important role in the developing brain by regulating a highly specific pattern of connections between nerve cells. Cell migration is required for axonal guidance and neurite outgrowth and involves a series of highly co-ordinated and overlapping signalling pathways. The non-receptor tyrosine kinase, Focal Adhesion Kinase (FAK) has an essential role in development and is the most highly expressed kinase in the developing CNS. FAK activity is essential for neuronal cell adhesion and migration. Results The objective of this study was to optimise a protocol for the differentiation of the neuroblastoma cell line, SH-SY5Y. We determined the optimal extracellular matrix proteins and growth factor combinations required for the optimal differentiation of SH-SY5Y cells into neuronal-like cells and determined those conditions that induce the expression of FAK. It was confirmed that the cells were morphologically and biochemically differentiated when compared to undifferentiated cells. This is in direct contrast to commonly used differentiation methods that induce morphological differentiation but not biochemical differentiation. Conclusions We conclude that we have optimised a protocol for the differentiation of SH-SY5Y cells that results in a cell population that is both morphologically and biochemically distinct from undifferentiated SH-SY5Y cells and has a distinct adhesion and spreading pattern and display extensive neurite outgrowth. This protocol will provide a neuronal model system for studying FAK activity during cell adhesion and migration events. PMID:24025096

RNAi knockdown of the focal adhesion protein TES reveals its role in actin stress fibre organisation.

PubMed

Griffith, Elen; Coutts, Amanda S; Black, Donald M

2005-03-01

TES was originally identified as a candidate tumour suppressor gene and has subsequently been found to encode a novel focal adhesion protein. As well as localising to cell-matrix adhesions, TES localises to cell-cell contacts and to actin stress fibres. TES interacts with a variety of cytoskeletal proteins including zyxin, mena, VASP, talin and actin. There is evidence that TES may function in actin-dependent processes as overexpression of TES results in increased cell spreading and decreased cell motility. Together with TES's interacting partners, these data suggest that TES might be involved in regulation of the actin cytoskeleton. Here, for the first time, we have used RNAi to successfully knockdown TES in HeLa cells and we demonstrate that loss of TES from focal adhesions results in loss of actin stress fibres. Similarly, and as previously reported, RNAi-mediated knockdown of zyxin results in loss of actin stress fibres. TES siRNA treated cells show reduced RhoA activity, suggesting that the Rho GTPase pathway may be involved in the TES RNAi-induced loss of stress fibres. We have also used RNAi to examine the requirement of TES and zyxin for each other's localisation at focal adhesions, and we propose a hierarchy of recruitment, with zyxin being first, followed by VASP and then TES. Cell Motil. Copyright 2005 Wiley-Liss, Inc.

Bio-active molecules modified surfaces enhanced mesenchymal stem cell adhesion and proliferation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mobasseri, Rezvan; Center for Nanofibers & Nanotechnology, Department of Mechanical Engineering, National University of Singapore, 117576; Tian, Lingling

Surface modification of the substrate as a component of in vitro cell culture and tissue engineering, using bio-active molecules including extracellular matrix (ECM) proteins or peptides derived ECM proteins can modulate the surface properties and thereby induce the desired signaling pathways in cells. The aim of this study was to evaluate the behavior of human bone marrow mesenchymal stem cells (hBM-MSCs) on glass substrates modified with fibronectin (Fn), collagen (Coll), RGD peptides (RGD) and designed peptide (R-pept) as bio-active molecules. The glass coverslips were coated with fibronectin, collagen, RGD peptide and R-peptide. Bone marrow mesenchymal stem cells were cultured on differentmore » substrates and the adhesion behavior in early incubation times was investigated using scanning electron microscopy (SEM) and confocal microscopy. The MTT assay was performed to evaluate the effect of different bio-active molecules on MSCs proliferation rate during 24 and 72 h. Formation of filopodia and focal adhesion (FA) complexes, two steps of cell adhesion process, were observed in MSCs cultured on bio-active molecules modified coverslips, specifically in Fn coated and R-pept coated groups. SEM image showed well adhesion pattern for MSCs cultured on Fn and R-pept after 2 h incubation, while the shape of cells cultured on Coll and RGD substrates indicated that they might experience stress condition in early hours of culture. Investigation of adhesion behavior, as well as proliferation pattern, suggests R-peptide as a promising bio-active molecule to be used for surface modification of substrate in supporting and inducing cell adhesion and proliferation. - Highlights: • Bioactive molecules modified surface is a strategy to design biomimicry scaffold. • Bi-functional Tat-derived peptide (R-pept) enhanced MSCs adhesion and proliferation. • R-pept showed similar influences to fibronectin on FA formation and attachment.« less

Mechanism of vaso-occlusion in sickle cell anemia

NASA Astrophysics Data System (ADS)

Lei, Huan; Karniadakis, George

2012-11-01

Vaso-occlusion crisis is one of the key hallmark of sickle cell anemia. While early studies suggested that the crisis is caused by blockage of a single elongated cell, recent experimental investigations indicate that vaso-occlusion is a complex process triggered by adhesive interactions among different cell groups in multiple stages. Based on dissipative particle dynamics, a multi-scale model for the sickle red blood cells (SS-RBCs), accounting for diversity in both shapes and cell rigidities, is developed to investigate the mechanism of vaso-occlusion crisis. Using this model, the adhesive dynamics of single SS-RBC was investigated in arterioles. Simulation results indicate that the different cell groups (deformable SS2 RBCs, rigid SS4 RBCs, leukocytes, etc.) exhibit heterogeneous adhesive behavior due to the different cell morphologies and membrane rigidities. We further simulate the tube flow of SS-RBC suspensions with different cell fractions. The more adhesive SS2 cells interact with the vascular endothelium and further trap rigid SS4 cells, resulting in vaso-occlusion in vessels less than 15 μm . Under inflammation, adherent leukocytes may also trap SS4 cells, resulting in vaso-occlusion in even larger vessels. This work was supported by the NSF grant CBET-0852948 and the NIH grant R01HL094270.

Focal adhesion kinase (FAK) perspectives in mechanobiology: implications for cell behaviour.

PubMed

Tomakidi, Pascal; Schulz, Simon; Proksch, Susanne; Weber, Wilfried; Steinberg, Thorsten

2014-09-01

Mechanobiology is a scientific interface discipline emerging from engineering and biology. With regard to tissue-regenerative cell-based strategies, mechanobiological concepts, including biomechanics as a target for cell and human mesenchymal stem cell behaviour, are on the march. Based on the periodontium as a paradigm, this mini-review discusses the key role of focal-adhesion kinase (FAK) in mechanobiology, since it is involved in mediating the transformation of environmental biomechanical signals into cell behavioural responses via mechanotransducing signalling cascades. These processes enable cells to adjust quickly to environmental cues, whereas adjustment itself relies on the specific intramolecular phosphorylation of FAK tyrosine residues and the multiple interactions of FAK with distinct partners. Furthermore, interaction-triggered mechanotransducing pathways govern the dynamics of focal adhesion sites and cell behaviour. Facets of behaviour not only include cell spreading and motility, but also proliferation, differentiation and apoptosis. In translational terms, identified and characterized biomechanical parameters can be incorporated into innovative concepts of cell- and tissue-tailored clinically applied biomaterials controlling cell behaviour as desired.

Cell Adhesions: Actin-Based Modules that Mediate Cell-Extracellular Matrix and Cell-Cell Interactions

PubMed Central

Bachir, Alexia; Horwitz, Alan Rick; Nelson, W. James; Bianchini, Julie M.

2018-01-01

Cell adhesions link cells to the extracellular matrix (ECM) and to each other, and depend on interactions with the actin cytoskeleton. Both cell-ECM and cell-cell adhesion sites contain discrete, yet overlapping functional modules. These modules establish physical association with the actin cytoskeleton, locally modulate actin organization and dynamics, and trigger intracellular signaling pathways. Interplay between these modules generates distinct actin architectures that underlie different stages, types, and functions of cell-ECM and cell-cell adhesions. Actomyosin contractility is required to generate mature, stable adhesions, as well as sense and translate the mechanical properties of the cellular environment to changes in cell organization and behavior. In this chapter we discuss the organization and function of different adhesion modules and how they interact with the actin cytoskeleton. We highlight the molecular mechanisms of mechanotransduction in adhesions, and how adhesion molecules mediate crosstalk between cell-ECM and cell-cell adhesion sites. PMID:28679638

Studies Using an in Vitro Model Show Evidence of Involvement of Epithelial-Mesenchymal Transition of Human Endometrial Epithelial Cells in Human Embryo Implantation*

PubMed Central

Uchida, Hiroshi; Maruyama, Tetsuo; Nishikawa-Uchida, Sayaka; Oda, Hideyuki; Miyazaki, Kaoru; Yamasaki, Akiko; Yoshimura, Yasunori

2012-01-01

Human embryo implantation is a critical multistep process consisting of embryo apposition/adhesion, followed by penetration and invasion. Through embryo penetration, the endometrial epithelial cell barrier is disrupted and remodeled by an unknown mechanism. We have previously developed an in vitro model for human embryo implantation employing the human choriocarcinoma cell line JAR and the human endometrial adenocarcinoma cell line Ishikawa. Using this model we have shown that stimulation with ovarian steroid hormones (17β-estradiol and progesterone, E2P4) and suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, enhances the attachment and adhesion of JAR spheroids to Ishikawa. In the present study we showed that the attachment and adhesion of JAR spheroids and treatment with E2P4 or SAHA individually induce the epithelial-mesenchymal transition (EMT) in Ishikawa cells. This was evident by up-regulation of N-cadherin and vimentin, a mesenchymal cell marker, and concomitant down-regulation of E-cadherin in Ishikawa cells. Stimulation with E2P4 or SAHA accelerated Ishikawa cell motility, increased JAR spheroid outgrowth, and enhanced the unique redistribution of N-cadherin, which was most prominent in proximity to the adhered spheroids. Moreover, an N-cadherin functional blocking antibody attenuated all events but not JAR spheroid adhesion. These results collectively provide evidence suggesting that E2P4- and implanting embryo-induced EMT of endometrial epithelial cells may play a pivotal role in the subsequent processes of human embryo implantation with functional control of N-cadherin. PMID:22174415

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

PubMed

Khalili, Amelia Ahmad; Ahmad, Mohd Ridzuan

2015-08-05

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.

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

Cell-to-cell interactions in changed gravity: Ground-based and flight experiments

NASA Astrophysics Data System (ADS)

Buravkova, L.; Romanov, Yu.; Rykova, M.; Grigorieva, O.; Merzlikina, N.

2005-07-01

Cell-to-cell interactions play an important role in all physiological processes and are mediated by humoral and mechanical factors. Mechanosensitive cells (e.g., osteocytes, chondrocytes, and fibroblasts) can be studied ex vivo to understand the effects of an altered gravity environment. In particular, cultured endothelial cells (EC) are very sensitive to a broad spectrum of mechanical and biochemical stimuli. Earlier, we demonstrated that clinorotation leads to cytoskeletal remodeling in cultured ECs. Long-term gravity vector changes also modulate the expression of surface adhesion molecules (ICAM-1, E-selectin, VCAM-1) on cultured ECs. To study the interactions of geterological cells, we cocultured endothelial monolayers and human lymphocytes, immune cells and myeloleucemic (K-560) cells. It was found that, although clinorotation did not alter the basal adhesion level of non-activated immune cells on endothelial monolayers, the adhesion of PMA-activated lymphocytes was increased. During flight experiments onboard the Russian segment of the International Space Station, we measured the cytotoxic activity of natural killer (NK) cells incubated with labeled target cells. It was found that immune cells in microgravity retained their ability to contact, recognize, and destroy oncogenic cells in vitro. Together, our data concerning the effects of simulated and real microgravity suggest that, despite changes in the cytoskeleton, cell motility, and expression of adhesion molecules, cell-cell interactions are not compromised, thus preserving the critical physiological functions of immune and endothelial cells.

Systems Biology Reveals Cigarette Smoke-Induced Concentration-Dependent Direct and Indirect Mechanisms That Promote Monocyte-Endothelial Cell Adhesion.

PubMed

Poussin, Carine; Laurent, Alexandra; Peitsch, Manuel C; Hoeng, Julia; De Leon, Hector

2015-10-01

Cigarette smoke (CS) affects the adhesion of monocytes to endothelial cells, a critical step in atherogenesis. Using an in vitro adhesion assay together with innovative computational systems biology approaches to analyze omics data, our study aimed at investigating CS-induced mechanisms by which monocyte-endothelial cell adhesion is promoted. Primary human coronary artery endothelial cells (HCAECs) were treated for 4 h with (1) conditioned media of human monocytic Mono Mac-6 (MM6) cells preincubated with low or high concentrations of aqueous CS extract (sbPBS) from reference cigarette 3R4F for 2 h (indirect treatment, I), (2) unconditioned media similarly prepared without MM6 cells (direct treatment, D), or (3) freshly generated sbPBS (fresh direct treatment, FD). sbPBS promoted MM6 cells-HCAECs adhesion following I and FD, but not D. In I, the effect was mediated at a low concentration through activation of vascular inflammation processes promoted in HCAECs by a paracrine effect of the soluble mediators secreted by sbPBS-treated MM6 cells. Tumor necrosis factor α (TNFα), a major inducer, was actually shed by unstable CS compound-activated TNFα-converting enzyme. In FD, the effect was triggered at a high concentration that also induced some toxicity. This effect was mediated through an yet unknown mechanism associated with a stress damage response promoted in HCAECs by unstable CS compounds present in freshly generated sbPBS, which had decayed in D unconditioned media. Aqueous CS extract directly and indirectly promotes monocytic cell-endothelial cell adhesion in vitro via distinct concentration-dependent mechanisms. © The Author 2015. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Receptor-mediated binding of IgE-sensitized rat basophilic leukemia cells to antigen-coated substrates under hydrodynamic flow.

PubMed Central

Tempelman, L A; Hammer, D A

1994-01-01

The physiological function of many cells is dependent on their ability to adhere via receptors to ligand-coated surfaces under fluid flow. We have developed a model experimental system to measure cell adhesion as a function of cell and surface chemistry and fluid flow. Using a parallel-plate flow chamber, we measured the binding of rat basophilic leukemia cells preincubated with anti-dinitrophenol IgE antibody to polyacrylamide gels covalently derivatized with 2,4-dinitrophenol. The rat basophilic leukemia cells' binding behavior is binary: cells are either adherent or continue to travel at their hydrodynamic velocity, and the transition between these two states is abrupt. The spatial location of adherent cells shows cells can adhere many cell diameters down the length of the gel, suggesting that adhesion is a probabilistic process. The majority of experiments were performed in the excess ligand limit in which adhesion depends strongly on the number of receptors but weakly on ligand density. Only 5-fold changes in IgE surface density or in shear rate were necessary to change adhesion from complete to indistinguishable from negative control. Adhesion showed a hyperbolic dependence on shear rate. By performing experiments with two IgE-antigen configurations in which the kinetic rates of receptor-ligand binding are different, we demonstrate that the forward rate of reaction of the receptor-ligand pair is more important than its thermodynamic affinity in the regulation of binding under hydrodynamic flow. In fact, adhesion increases with increasing receptor-ligand reaction rate or decreasing shear rate, and scales with a single dimensionless parameter which compares the relative rates of reaction to fluid shear. Images FIGURE 2 FIGURE 3 FIGURE 6 FIGURE 8 FIGURE 10 PMID:8038394

Allosteric Regulation of E-Cadherin Adhesion*

PubMed Central

Shashikanth, Nitesh; Petrova, Yuliya I.; Park, Seongjin; Chekan, Jillian; Maiden, Stephanie; Spano, Martha; Ha, Taekjip; Gumbiner, Barry M.; Leckband, Deborah E.

2015-01-01

Cadherins are transmembrane adhesion proteins that maintain intercellular cohesion in all tissues, and their rapid regulation is essential for organized tissue remodeling. Despite some evidence that cadherin adhesion might be allosterically regulated, testing of this has been hindered by the difficulty of quantifying altered E-cadherin binding affinity caused by perturbations outside the ectodomain binding site. Here, measured kinetics of cadherin-mediated intercellular adhesion demonstrated quantitatively that treatment with activating, anti-E-cadherin antibodies or the dephosphorylation of a cytoplasmic binding partner, p120ctn, increased the homophilic binding affinity of E-cadherin. Results obtained with Colo 205 cells, which express inactive E-cadherin and do not aggregate, demonstrated that four treatments, which induced Colo 205 aggregation and p120ctn dephosphorylation, triggered quantitatively similar increases in E-cadherin affinity. Several processes can alter cell aggregation, but these results directly demonstrated the allosteric regulation of cell surface E-cadherin by p120ctn dephosphorylation. PMID:26175155

Engineered Protein Coatings to Improve the Osseointegration of Dental and Orthopaedic Implants

PubMed Central

Raphel, Jordan; Karlsson, Johan; Galli, Silvia; Wennerberg, Ann; Lindsay, Christopher; Haugh, Matthew; Pajarinen, Jukka; Goodman, Stuart B.; Jimbo, Ryo; Andersson, Martin; Heilshorn, Sarah C.

2016-01-01

Here we present the design of an engineered, elastin-like protein (ELP) that is chemically modified to enable stable coatings on the surfaces of titanium-based dental and orthopaedic implants by novel photocrosslinking and solution processing steps. The ELP includes an extended RGD sequence to confer bio-signaling and an elastin-like sequence for mechanical stability. ELP thin films were fabricated on cp-Ti and Ti6Al4V surfaces using scalable spin and dip coating processes with photoactive covalent crosslinking through a carbene insertion mechanism. The coatings withstood procedures mimicking dental screw and hip replacement stem implantations, a key metric for clinical translation. They promoted rapid adhesion of MG63 osteoblast-like cells, with over 80% adhesion after 24 hours, compared to 38% adhesion on uncoated Ti6Al4V. MG63 cells produced significantly more mineralization on ELP coatings compared to uncoated Ti6Al4V. Human bone marrow mesenchymal stem cells (hMSCs) had an earlier increase in alkaline phosphatase activity, indicating more rapid osteogenic differentiation and mineral deposition on adhesive ELP coatings. Rat tibia and femur in vivo studies demonstrated that cell-adhesive ELP-coated implants increased bone-implant contact area and interfacial strength after one week. These results suggest that ELP coatings withstand surgical implantation and promote rapid osseointegration, enabling earlier implant loading and potentially preventing micromotion that leads to aseptic loosening and premature implant failure. PMID:26790146

A Functional Analysis on the Interspecies Interaction between Mouse LFA-1 and Human Intercellular Adhesion Molecule-1 at the Cell Level

PubMed Central

Núñez, David; Comas, Laura; Lanuza, Pilar M.; Sánchez-Martinez, Diego; Pérez-Hernández, Marta; Catalán, Elena; Domingo, María Pilar; Velázquez-Campoy, Adrián; Pardo, Julián; Gálvez, Eva M.

2017-01-01

The interaction between intercellular adhesion molecules (ICAM) and the integrin leukocyte function-associated antigen-1 (LFA-1) is crucial for the regulation of several physiological and pathophysiological processes like cell-mediated elimination of tumor or virus infected cells, cancer metastasis, or inflammatory and autoimmune processes. Using purified proteins it was reported a species restriction for the interaction of ICAM-1 and LFA-1, being mouse ICAM-1 able to interact with human LFA-1 but not human ICAM-1 with mouse LFA-1. However, in vivo results employing tumor cells transfected with human ICAM-1 suggest that functionally mouse LFA-1 can recognize human ICAM-1. In order to clarify the interspecies cross-reactivity of the ICAM-1/LFA-1 interaction, we have performed functional studies analyzing the ability of human soluble ICAM-1 and human/mouse LFA-1 derived peptides to inhibit cell aggregation and adhesion as well as cell-mediated cytotoxicity in both mouse and human systems. In parallel, the affinity of the interaction between mouse LFA-1-derived peptides and human ICAM-1 was determined by calorimetry assays. According to the results obtained, it seems that human ICAM-1 is able to interact with mouse LFA-1 on intact cells, which should be taking into account when using humanized mice and xenograft models for the study of immune-related processes. PMID:29312326

A Functional Analysis on the Interspecies Interaction between Mouse LFA-1 and Human Intercellular Adhesion Molecule-1 at the Cell Level.

PubMed

Núñez, David; Comas, Laura; Lanuza, Pilar M; Sánchez-Martinez, Diego; Pérez-Hernández, Marta; Catalán, Elena; Domingo, María Pilar; Velázquez-Campoy, Adrián; Pardo, Julián; Gálvez, Eva M

2017-01-01

The interaction between intercellular adhesion molecules (ICAM) and the integrin leukocyte function-associated antigen-1 (LFA-1) is crucial for the regulation of several physiological and pathophysiological processes like cell-mediated elimination of tumor or virus infected cells, cancer metastasis, or inflammatory and autoimmune processes. Using purified proteins it was reported a species restriction for the interaction of ICAM-1 and LFA-1, being mouse ICAM-1 able to interact with human LFA-1 but not human ICAM-1 with mouse LFA-1. However, in vivo results employing tumor cells transfected with human ICAM-1 suggest that functionally mouse LFA-1 can recognize human ICAM-1. In order to clarify the interspecies cross-reactivity of the ICAM-1/LFA-1 interaction, we have performed functional studies analyzing the ability of human soluble ICAM-1 and human/mouse LFA-1 derived peptides to inhibit cell aggregation and adhesion as well as cell-mediated cytotoxicity in both mouse and human systems. In parallel, the affinity of the interaction between mouse LFA-1-derived peptides and human ICAM-1 was determined by calorimetry assays. According to the results obtained, it seems that human ICAM-1 is able to interact with mouse LFA-1 on intact cells, which should be taking into account when using humanized mice and xenograft models for the study of immune-related processes.

Topography of Cells Revealed by Variable-Angle Total Internal Reflection Fluorescence Microscopy.

PubMed

Cardoso Dos Santos, Marcelina; Déturche, Régis; Vézy, Cyrille; Jaffiol, Rodolphe

2016-09-20

We propose an improved version of variable-angle total internal reflection fluorescence microscopy (vaTIRFM) adapted to modern TIRF setup. This technique involves the recording of a stack of TIRF images, by gradually increasing the incident angle of the light beam on the sample. A comprehensive theory was developed to extract the membrane/substrate separation distance from fluorescently labeled cell membranes. A straightforward image processing was then established to compute the topography of cells with a nanometric axial resolution, typically 10-20 nm. To highlight the new opportunities offered by vaTIRFM to quantify adhesion process of motile cells, adhesion of MDA-MB-231 cancer cells on glass substrate coated with fibronectin was examined. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

3D polylactide-based scaffolds for studying human hepatocarcinoma processes in vitro

NASA Astrophysics Data System (ADS)

Scaffaro, Roberto; Lo Re, Giada; Rigogliuso, Salvatrice; Ghersi, Giulio

2012-08-01

We evaluated the combination of leaching techniques and melt blending of polymers and particles for the preparation of highly interconnected three-dimensional polymeric porous scaffolds for in vitro studies of human hepatocarcinoma processes. More specifically, sodium chloride and poly(ethylene glycol) (PEG) were used as water-soluble porogens to form porous and solvent-free poly(L,D-lactide) (PLA)-based scaffolds. Several characterization techniques, including porosimetry, image analysis and thermogravimetry, were combined to improve the reliability of measurements and mapping of the size, distribution and microarchitecture of pores. We also investigated the effect of processing, in PLA-based blends, on the simultaneous bulk/surface modifications and pore architectures in the scaffolds, and assessed the effects on human hepatocarcinoma viability and cell adhesion. The influence of PEG molecular weight on the scaffold morphology and cell viability and adhesion were also investigated. Morphological studies indicated that it was possible to obtain scaffolds with well-interconnected pores of assorted sizes. The analysis confirmed that SK-Hep1 cells adhered well to the polymeric support and emitted surface protrusions necessary to grow and differentiate three-dimensional systems. PEGs with higher molecular weight showed the best results in terms of cell adhesion and viability.

The Neural Cell Adhesion Molecule-Derived Peptide FGL Facilitates Long-Term Plasticity in the Dentate Gyrus in Vivo

ERIC Educational Resources Information Center

Dallerac, Glenn; Zerwas, Meike; Novikova, Tatiana; Callu, Delphine; Leblanc-Veyrac, Pascale; Bock, Elisabeth; Berezin, Vladimir; Rampon, Claire; Doyere, Valerie

2011-01-01

The neural cell adhesion molecule (NCAM) is known to play a role in developmental and structural processes but also in synaptic plasticity and memory of the adult animal. Recently, FGL, a NCAM mimetic peptide that binds to the Fibroblast Growth Factor Receptor 1 (FGFR-1), has been shown to have a beneficial impact on normal memory functioning, as…

Proliferation and osteogenic differentiation of rat BMSCs on a novel Ti/SiC metal matrix nanocomposite modified by friction stir processing

NASA Astrophysics Data System (ADS)

Zhu, Chenyuan; Lv, Yuting; Qian, Chao; Qian, Haixin; Jiao, Ting; Wang, Liqiang; Zhang, Fuqiang

2016-12-01

The aims of this study were to fabricate a novel titanium/silicon carbide (Ti/SiC) metal matrix nanocomposite (MMNC) by friction stir processing (FSP) and to investigate its microstructure and mechanical properties. In addition, the adhesion, proliferation and osteogenic differentiation of rat bone marrow stromal cells (BMSCs) on the nanocomposite surface were investigated. The MMNC microstructure was observed by both scanning and transmission electron microscopy. Mechanical properties were characterized by nanoindentation and Vickers hardness testing. Integrin β1 immunofluorescence, cell adhesion, and MTT assays were used to evaluate the effects of the nanocomposite on cell adhesion and proliferation. Osteogenic and angiogenic differentiation were evaluated by alkaline phosphatase (ALP) staining, ALP activity, PCR and osteocalcin immunofluorescence. The observed microstructures and mechanical properties clearly indicated that FSP is a very effective technique for modifying Ti/SiC MMNC to contain uniformly distributed nanoparticles. In the interiors of recrystallized grains, characteristics including twins, fine recrystallized grains, and dislocations formed concurrently. Adhesion, proliferation, and osteogenic and angiogenic differentiation of rat BMSCs were all enhanced on the novel Ti/SiC MMNC surface. In conclusion, nanocomposites modified using FSP technology not only have superior mechanical properties under stress-bearing conditions but also provide improved surface and physicochemical properties for cell attachment and osseointegration.

Roles of the cytoskeleton, cell adhesion and rho signalling in mechanosensing and mechanotransduction.

PubMed

Ohashi, Kazumasa; Fujiwara, Sachiko; Mizuno, Kensaku

2017-03-01

All cells sense and respond to various mechanical forces in and mechanical properties of their environment. To respond appropriately, cells must be able to sense the location, direction, strength and duration of these forces. Recent progress in mechanobiology has provided a better understanding of the mechanisms of mechanoresponses underlying many cellular and developmental processes. Various roles of mechanoresponses in development and tissue homeostasis have been elucidated, and many molecules involved in mechanotransduction have been identified. However, the whole picture of the functions and molecular mechanisms of mechanotransduction remains to be understood. Recently, novel mechanisms for sensing and transducing mechanical stresses via the cytoskeleton, cell-substrate and cell-cell adhesions and related proteins have been identified. In this review, we outline the roles of the cytoskeleton, cell-substrate and cell-cell adhesions, and related proteins in mechanosensing and mechanotransduction. We also describe the roles and regulation of Rho-family GTPases in mechanoresponses. © The Authors 2017. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.

SLAT promotes TCR-mediated, Rap1-dependent LFA-1 activation and adhesion through interaction of its PH domain with Rap1

PubMed Central

Côte, Marjorie; Fos, Camille; Canonigo-Balancio, Ann J.; Ley, Klaus; Bécart, Stéphane; Altman, Amnon

2015-01-01

ABSTRACT SLAT (also known as DEF6) promotes T cell activation and differentiation by regulating NFAT-Ca2+ signaling. However, its role in TCR-mediated inside-out signaling, which induces integrin activation and T cell adhesion, a central process in T cell immunity and inflammation, has not been explored. Here, we show that SLAT is crucial for TCR-induced adhesion to ICAM-1 and affinity maturation of LFA-1 in CD4+ T cells. Mechanistic studies revealed that SLAT interacts, through its PH domain, with a key component of inside-out signaling, namely the active form of the small GTPase Rap1 (which has two isoforms, Rap1A and Rap1B). This interaction has been further shown to facilitate the interdependent recruitment of Rap1 and SLAT to the T cell immunological synapse upon TCR engagement. Furthermore, a SLAT mutant lacking its PH domain drastically inhibited LFA-1 activation and CD4+ T cell adhesion. Finally, we established that a constitutively active form of Rap1, which is present at the plasma membrane, rescues the defective LFA-1 activation and ICAM-1 adhesion in SLAT-deficient (Def6−/−) T cells. These findings ascribe a new function to SLAT, and identify Rap1 as a target of SLAT function in TCR-mediated inside-out signaling. PMID:26483383

SLAT promotes TCR-mediated, Rap1-dependent LFA-1 activation and adhesion through interaction of its PH domain with Rap1.

PubMed

Côte, Marjorie; Fos, Camille; Canonigo-Balancio, Ann J; Ley, Klaus; Bécart, Stéphane; Altman, Amnon

2015-12-01

SLAT (also known as DEF6) promotes T cell activation and differentiation by regulating NFAT-Ca(2+) signaling. However, its role in TCR-mediated inside-out signaling, which induces integrin activation and T cell adhesion, a central process in T cell immunity and inflammation, has not been explored. Here, we show that SLAT is crucial for TCR-induced adhesion to ICAM-1 and affinity maturation of LFA-1 in CD4(+) T cells. Mechanistic studies revealed that SLAT interacts, through its PH domain, with a key component of inside-out signaling, namely the active form of the small GTPase Rap1 (which has two isoforms, Rap1A and Rap1B). This interaction has been further shown to facilitate the interdependent recruitment of Rap1 and SLAT to the T cell immunological synapse upon TCR engagement. Furthermore, a SLAT mutant lacking its PH domain drastically inhibited LFA-1 activation and CD4(+) T cell adhesion. Finally, we established that a constitutively active form of Rap1, which is present at the plasma membrane, rescues the defective LFA-1 activation and ICAM-1 adhesion in SLAT-deficient (Def6(-/-)) T cells. These findings ascribe a new function to SLAT, and identify Rap1 as a target of SLAT function in TCR-mediated inside-out signaling. © 2015. Published by The Company of Biologists Ltd.

Plasmodium falciparum Adhesion on Human Brain Microvascular Endothelial Cells Involves Transmigration-Like Cup Formation and Induces Opening of Intercellular Junctions

PubMed Central

Jambou, Ronan; Combes, Valery; Jambou, Marie-Jose; Weksler, Babeth B.; Couraud, Pierre-Olivier; Grau, Georges E.

2010-01-01

Cerebral malaria, a major cause of death during malaria infection, is characterised by the sequestration of infected red blood cells (IRBC) in brain microvessels. Most of the molecules implicated in the adhesion of IRBC on endothelial cells (EC) are already described; however, the structure of the IRBC/EC junction and the impact of this adhesion on the EC are poorly understood. We analysed this interaction using human brain microvascular EC monolayers co-cultured with IRBC. Our study demonstrates the transfer of material from the IRBC to the brain EC plasma membrane in a trogocytosis-like process, followed by a TNF-enhanced IRBC engulfing process. Upon IRBC/EC binding, parasite antigens are transferred to early endosomes in the EC, in a cytoskeleton-dependent process. This is associated with the opening of the intercellular junctions. The transfer of IRBC antigens can thus transform EC into a target for the immune response and contribute to the profound EC alterations, including peri-vascular oedema, associated with cerebral malaria. PMID:20686652

Project STOP (Spectral Thermal Optimization Program)

NASA Technical Reports Server (NTRS)

Goldhammer, L. J.; Opjorden, R. W.; Goodelle, G. S.; Powe, J. S.

1977-01-01

The spectral thermal optimization of solar cell configurations for various solar panel applications is considered. The method of optimization depends upon varying the solar cell configuration's optical characteristics to minimize panel temperatures, maximize power output and decrease the power delta from beginning of life to end of life. Four areas of primary investigation are: (1) testing and evaluation of ultraviolet resistant coverslide adhesives, primarily FEP as an adhesive; (2) examination of solar cell absolute spectral response and corresponding cell manufacturing processes that affect it; (3) experimental work with solar cell manufacturing processes that vary cell reflectance (solar absorptance); and (4) experimental and theoretical studies with various coverslide filter designs, mainly a red rejection filter. The Hughes' solar array prediction program has been modified to aid in evaluating the effect of each of the above four areas on the output of a solar panel in orbit.

Soluble adhesion molecules in human cancers: sources and fates.

PubMed

van Kilsdonk, Jeroen W J; van Kempen, Léon C L T; van Muijen, Goos N P; Ruiter, Dirk J; Swart, Guido W M

2010-06-01

Adhesion molecules endow tumor cells with the necessary cell-cell contacts and cell-matrix interactions. As such, adhesion molecules are involved in cell signalling, proliferation and tumor growth. Rearrangements in the adhesion repertoire allow tumor cells to migrate, invade and form metastases. Besides these membrane-bound adhesion molecules several soluble adhesion molecules are detected in the supernatant of tumor cell lines and patient body fluids. Truncated soluble adhesion molecules can be generated by several conventional mechanisms, including alternative splicing of mRNA transcripts, chromosomal translocation, and extracellular proteolytic ectodomain shedding. Secretion of vesicles (ectosomes and exosomes) is an alternative mechanism mediating the release of full-length adhesion molecules. Soluble adhesion molecules function as modulators of cell adhesion, induce proteolytic activity and facilitate cell signalling. Additionally, adhesion molecules present on secreted vesicles might be involved in the vesicle-target cell interaction. Based on currently available data, released soluble adhesion molecules contribute to cancer progression and therefore should not be regarded as unrelated and non-functional side products of tumor progression. 2010 Elsevier GmbH. All rights reserved.

The roles of cell adhesion molecules in tumor suppression and cell migration: a new paradox.

PubMed

Moh, Mei Chung; Shen, Shali

2009-01-01

In addition to mediating cell adhesion, many cell adhesion molecules act as tumor suppressors. These proteins are capable of restricting cell growth mainly through contact inhibition. Alterations of these cell adhesion molecules are a common event in cancer. The resulting loss of cell-cell and/or cell-extracellular matrix adhesion promotes cell growth as well as tumor dissemination. Therefore, it is conventionally accepted that cell adhesion molecules that function as tumor suppressors are also involved in limiting tumor cell migration. Paradoxically, in 2005, we identified an immunoglobulin superfamily cell adhesion molecule hepaCAM that is able to suppress cancer cell growth and yet induce migration. Almost concurrently, CEACAM1 was verified to co-function as a tumor suppressor and invasion promoter. To date, the reason and mechanism responsible for this exceptional phenomenon remain unclear. Nevertheless, the emergence of these intriguing cell adhesion molecules with conflicting roles may open a new chapter to the biological significance of cell adhesion molecules.

Niacin results in reduced monocyte adhesion in patients with type 2 diabetes mellitus.

PubMed

Tavintharan, S; Woon, K; Pek, L T; Jauhar, N; Dong, X; Lim, S C; Sum, C F

2011-03-01

Patients with type 2 diabetes have increased expression of cell adhesion molecules (CAMs). CAMs and monocyte adhesion mediate essential processes in atherogenesis. It remains unclear if monocytes from patients on niacin have reduced adhesion function. We studied the variation of monocyte adhesion in patients with type 2 diabetes and low HDL-cholesterol, taking either extended release niacin (Niaspan®, Abbott Laboratories) or controls not on niacin. Biochemical parameters including adiponectin, CAMs and fresh monocytes from whole blood for adhesion assays, were studied at baseline and 12-weeks. Niacin 1500 mg daily raised HDL-cholesterol from 0.8 mmol/l (95% CI: 0.7-0.9) to 0.9 mmol/l (95% CI: 0.8-1.1), p=0.10, and significantly reduced PECAM-1 by 24.9% (95% CI: 10.9-39.0; p<0.05), increased adiponectin by 30.5% (95% CI: 14.1-47.0; p<0.05), with monocyte adhesion reduced by 9.2% (95%CI: 0.7-17.7; p<0.05) in endothelial cells treated in basal conditions, and 7.8% (95% CI: 3.1-12.5; p<0.05) after TNF-α stimulation. Monocytes isolated from patients on niacin had reduced adhesion to endothelial cells. Our findings suggest niacin has broad range of effects apart from lipid-modification, and these could be important in cardiovascular risk reduction. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Suppression of lysyl-tRNA synthetase, KRS, causes incomplete epithelial-mesenchymal transition and ineffective cell‑extracellular matrix adhesion for migration.

PubMed

Nam, Seo Hee; Kang, Minkyung; Ryu, Jihye; Kim, Hye-Jin; Kim, Doyeun; Kim, Dae Gyu; Kwon, Nam Hoon; Kim, Sunghoon; Lee, Jung Weon

2016-04-01

The cell-adhesion properties of cancer cells can be targeted to block cancer metastasis. Although cytosolic lysyl-tRNA synthetase (KRS) functions in protein synthesis, KRS on the plasma membrane is involved in cancer metastasis. We hypothesized that KRS is involved in cell adhesion-related signal transduction for cellular migration. To test this hypothesis, colon cancer cells with modulated KRS protein levels were analyzed for cell-cell contact and cell-substrate adhesion properties and cellular behavior. Although KRS suppression decreased expression of cell-cell adhesion molecules, cells still formed colonies without being scattered, supporting an incomplete epithelial mesenchymal transition. Noteworthy, KRS-suppressed cells still exhibited focal adhesions on laminin, with Tyr397-phopshorylated focal adhesion kinase (FAK), but they lacked laminin-adhesion-mediated extracellular signal-regulated kinase (ERK) and paxillin activation. KRS, p67LR and integrin α6β1 were found to interact, presumably to activate ERK for paxillin expression and Tyr118 phosphorylation even without involvement of FAK, so that specific inhibition of ERK or KRS in parental HCT116 cells blocked cell-cell adhesion and cell-substrate properties for focal adhesion formation and signaling activity. Together, these results indicate that KRS can promote cell-cell and cell-ECM adhesion for migration.

Focal adhesions and Ras are functionally and spatially integrated to mediate IL-1 activation of ERK

PubMed Central

Wang, Qin; Downey, Gregory P.; McCulloch, Christopher A.

2011-01-01

In connective tissue cells, IL-1-induced ERK activation leading to matrix metalloproteinase (MMP)-3 expression is dependent on cooperative interactions between focal adhesions and the endoplasmic reticulum (ER). As Ras can be activated on the ER, we investigated the role of Ras in IL-1 signaling and focal adhesion formation. We found that constitutively active H-Ras, K-Ras or N-Ras enhanced focal adhesion maturation and β1-integrin activation. IL-1 promoted the accumulation of Ras isoforms in ER and focal adhesion fractions, as shown in cells cotransfected with GFP-tagged Ras isoforms and YFP-ER protein and by analysis of subcellular fractions enriched for ER or focal adhesion proteins. Dominant-negative H-Ras or K-Ras reduced accumulation of H-Ras and K-Ras in focal adhesions induced by IL-1 and also blocked ERK activation and focal adhesion maturation. Ras-GRF was enriched constitutively in focal adhesion fractions and was required for Ras recruitment to focal adhesions. We conclude that Ras activation and IL-1 signaling are interactive processes that regulate the maturation of focal adhesions, which, in turn, is required for ERK activation.—Wang, Q., Downey, G. P., McCulloch, C. A. Focal adhesions and Ras are functionally and spatially integrated to mediate IL-1 activation of ERK. PMID:21719512

Chemoresistance induces enhanced adhesion and transendothelial penetration of neuroblastoma cells by down-regulating NCAM surface expression

PubMed Central

Blaheta, Roman A; Daher, Frederick H; Michaelis, Martin; Hasenberg, Christoph; Weich, Eva M; Jonas, Dietger; Kotchetkov, Rouslan; Doerr, Hans Willhelm; Cinatl, Jindrich

2006-01-01

Background Drug resistance to chemotherapy is often associated with increased malignancy in neuroblastoma (NB). One explanation for the link between resistance and malignancy might be that resistance facilitates cancer progression and invasion. To investigate this hypothesis, adhesion, transendothelial penetration and NCAM (CD56) adhesion receptor expression of drug-resistant versus drug-sensitive NB tumor cells were evaluated. Methods Acquired drug resistance was mimicked by exposing parental UKF-NB-2, UKF-NB-3 or IMR-32 tumor cells to increasing concentrations of vincristine- (VCR) or doxorubicin (DOX) to establish the resistant tumor cell sublines UKF-NB-2VCR, UKF-NB-2DOX, UKF-NB-3VCR, UKF-NB-3DOX, IMR-32VCR and IMR-32DOX. Additionally, the malignant behaviour of UKF-NB-4, which already possessed the intrinsic multidrug resistance (MDR) phenotype, was analyzed. UKF-NB-4 exposed to VCR or DOX were designated UKF-NB-4VCR or UKF-NB-4DOX. Combined phase contrast – reflection interference contrast microscopy was used to separately evaluate NB cell adhesion and penetration. NCAM was analyzed by flow cytometry, western blot and RT-PCR. Results VCR and DOX resistant tumor sublines showed enhanced adhesion and penetration capacity, compared to their drug naïve controls. Strongest effects were seen with UKF-NB-2VCR, UKF-NB-3VCR and IMR-32DOX. DOX or VCR treatment also evoked increased invasive behaviour of UKF-NB-4. The process of accelerated tumor invasion was accompanied by decreased NCAM surface and protein expression, and down-regulation of NCAM coding mRNA. Transfection of UKF-NB-4VCR cells with NCAM cDNA led to a significant receptor up-regulation, paralleled by diminished adhesion to an endothelial cell monolayer. Conclusion It is concluded that NB cells resistant to anticancer drugs acquire increased invasive capacity relative to non-resistant parental cells, and that enhanced invasion is caused by strong down-regulation of NCAM adhesion receptors. PMID:17181871

Platelet-Poor Plasma as a Supplement for Fibroblasts Cultured in Platelet-Rich Fibrin

PubMed Central

Karam, Sarah Arangurem; Noronha, Thaís Gioda; Sartori, Letícia Regina Morello; San Martin, Alissa Schmidt; Demarco, Flávio Fernando; Conde, Marcus Cristian Muniz

2017-01-01

The aim of this study was to evaluate the proliferation and adhesion of mesenchymal cells (3T3/NIH) in Dulbecco’s Modified Eagle Medium(DMEM) supplemented with Platelet-Poor Plasma (PPP) in aPlatelet-Rich Fibrin (PRF) scaffold. Human blood was obtained and processed in a centrifuge considering the equation G=1.12xRx(RPM/1000)2 to obtain PRF and PPP.Cell adhesion and maintenance analyses were performed by MTTassays in a 96 well plate withsupplemented DMEM: PPP (90:10) for 24 hours. Besides, the PRF was deposited in a 48 well plate and 10x104 cells were seeded above each PRF (n=3) with 800µl of DMEM: PPP (90:10) and cultured for 7 days. Histological analysis and the immunohistochemical staining for Vimentin were performed. Results were analyzed by one-way ANOVA in Stata12®. A significant decrease (p<0.05) of cells adhesion in relationship to FBSwas observed. However, a similar ability of cell-maintenance for PPP 10% was observed (P>0.05). Fibroblasts culture for 7 days in PRF supplemented with PPP 10% was possible, showing positive staining for Vimentin. Therefore, PPP cell supplementation decreased the initial adhesion of cells but was able to maintain the proliferation of adhered cells and able to support their viability in PRF.It seems that this method has many clinical advantagessince it provides an autologous and natural scaffold with their respective supplement for cell culture by only one process, without using xenogeneic compounds. This could improve the potential of clinical translational therapies based on the use of PRF cultured cells, promoting the regenerative potential for future use in medicine and dentistry. PMID:28827850

An easily accessible sulfated saccharide mimetic inhibits in vitro human tumor cell adhesion and angiogenesis of vascular endothelial cells

PubMed Central

Marano, Grazia; Gronewold, Claas; Frank, Martin; Merling, Anette; Kliem, Christian; Sauer, Sandra; Wiessler, Manfred; Frei, Eva

2012-01-01

Summary Oligosaccharides aberrantly expressed on tumor cells influence processes such as cell adhesion and modulation of the cell’s microenvironment resulting in an increased malignancy. Schmidt’s imidate strategy offers an effective method to synthesize libraries of various oligosaccharide mimetics. With the aim to perturb interactions of tumor cells with extracellular matrix proteins and host cells, molecules with 3,4-bis(hydroxymethyl)furan as core structure were synthesized and screened in biological assays for their abilities to interfere in cell adhesion and other steps of the metastatic cascade, such as tumor-induced angiogenesis. The most active compound, (4-{[(β-D-galactopyranosyl)oxy]methyl}furan-3-yl)methyl hydrogen sulfate (GSF), inhibited the activation of matrix-metalloproteinase-2 (MMP-2) as well as migration of the human melanoma cells of the lines WM-115 and WM-266-4 in a two-dimensional migration assay. GSF inhibited completely the adhesion of WM-115 cells to the extracellular matrix (ECM) proteins, fibrinogen and fibronectin. In an in vitro angiogenesis assay with human endothelial cells, GSF very effectively inhibited endothelial tubule formation and sprouting of blood vessels, as well as the adhesion of endothelial cells to ECM proteins. GSF was not cytotoxic at biologically active concentrations; neither were 3,4-bis{[(β-D-galactopyranosyl)oxy]methyl}furan (BGF) nor methyl β-D-galactopyranoside nor 3,4-bis(hydroxymethyl)furan, which were used as controls, eliciting comparable biological activity. In silico modeling experiments, in which binding of GSF to the extracellular domain of the integrin αvβ3 was determined, revealed specific docking of GSF to the same binding site as the natural peptidic ligands of this integrin. The sulfate in the molecule coordinated with one manganese ion in the binding site. These studies show that this chemically easily accessible molecule GSF, synthesized in three steps from 3,4-bis(hydroxymethyl)furan and benzoylated galactose imidate, is nontoxic and antagonizes cell physiological processes in vitro that are important for the dissemination and growth of tumor cells in vivo. PMID:23015827

Actin-Based Adhesion Modules Mediate Cell Interactions with the Extracellular Matrix and Neighboring Cells.

PubMed

Bachir, Alexia I; Horwitz, Alan Rick; Nelson, W James; Bianchini, Julie M

2017-07-05

Cell adhesions link cells to the extracellular matrix (ECM) and to each other and depend on interactions with the actin cytoskeleton. Both cell-ECM and cell-cell adhesion sites contain discrete, yet overlapping, functional modules. These modules establish physical associations with the actin cytoskeleton, locally modulate actin organization and dynamics, and trigger intracellular signaling pathways. Interplay between these modules generates distinct actin architectures that underlie different stages, types, and functions of cell-ECM and cell-cell adhesions. Actomyosin contractility is required to generate mature, stable adhesions, as well as to sense and translate the mechanical properties of the cellular environment into changes in cell organization and behavior. Here, we review the organization and function of different adhesion modules and how they interact with the actin cytoskeleton. We highlight the molecular mechanisms of mechanotransduction in adhesions and how adhesion molecules mediate cross talk between cell-ECM and cell-cell adhesion sites. Copyright © 2017 Cold Spring Harbor Laboratory Press; all rights reserved.

Nanoscale TiO2 nanotubes govern the biological behavior of human glioma and osteosarcoma cells

PubMed Central

Tian, Ang; Qin, Xiaofei; Wu, Anhua; Zhang, Hangzhou; Xu, Quan; Xing, Deguang; Yang, He; Qiu, Bo; Xue, Xiangxin; Zhang, Dongyong; Dong, Chenbo

2015-01-01

Cells respond to their surroundings through an interactive adhesion process that has direct effects on cell proliferation and migration. This research was designed to investigate the effects of TiO2 nanotubes with different topographies and structures on the biological behavior of cultured cells. The results demonstrated that the nanotube diameter, rather than the crystalline structure of the coatings, was a major factor for the biological behavior of the cultured cells. The optimal diameter of the nanotubes was 20 nm for cell adhesion, migration, and proliferation in both glioma and osteosarcoma cells. The expression levels of vitronectin and phosphor-focal adhesion kinase were affected by the nanotube diameter; therefore, it is proposed that the responses of vitronectin and phosphor-focal adhesion kinase to the nanotube could modulate cell fate. In addition, the geometry and size of the nanotube coating could regulate the degree of expression of acetylated α-tubulin, thus indirectly modulating cell migration behavior. Moreover, the expression levels of apoptosis-associated proteins were influenced by the topography. In conclusion, a nanotube diameter of 20 nm was the critical threshold that upregulated the expression level of Bcl-2 and obviously decreased the expression levels of Bax and caspase-3. This information will be useful for future biomedical and clinical applications. PMID:25848261

High-density lipoprotein of patients with breast cancer complicated with type 2 diabetes mellitus promotes cancer cells adhesion to vascular endothelium via ICAM-1 and VCAM-1 upregulation.

PubMed

Huang, Xiaoqin; He, Dan; Ming, Jia; He, Yubin; Zhou, Champion; Ren, Hui; He, Xin; Wang, Chenguang; Jin, Jingru; Ji, Liang; Willard, Belinda; Pan, Bing; Zheng, Lemin

2016-02-01

Adhesion of disseminating tumor cells to vascular endothelium is a pivotal starting point in the metastasis cascade. We have shown previously that diabetic high-density lipoprotein (HDL) has the capability of promoting breast cancer metastasis, and this report summarizes our more recent work studying the role of abnormal HDL in facilitating the adhesion of the circulating tumor cells to the endothelium. This is an initiating step in breast cancer metastasis, and this work assesses the role of ICAM-1 and VCAM-1 in this process. MDA-MB-231, MCF 7, and human umbilical vein endothelial cells (HUVECs) were treated with normal HDL from healthy controls (N-HDL), HDL from breast cancer patients (B-HDL), or HDL from breast cancer patients complicated with type 2 diabetes mellitus (BD-HDL), and the cell adhesion abilities were determined. ICAM-1 and VCAM-1 expression as well as the protein kinase C (PKC) activity were evaluated. The effect of PKC inhibitor and PKC siRNA on adhesion was also studied. The immunohistochemical staining of ICAM-1, VCAM-1, and E-selectin from breast cancer patients and breast cancer patients complicated with type 2 diabetes mellitus (T2DM) were examined. Our results indicate that BD-HDL promoted an increase in breast cancer cell adhesion to HUVECs and stimulated higher ICAM-1 and VCAM-1 expression on the cells surface of both breast cancer and HUVEC cells, along with the activation of PKC. Increased tumor cell (TC)-HUVEC adhesion, as well as ICAM-1 and VCAM-1 expression induced by BD-HDL, could be inhibited by staurosporine and PKC siRNA. In addition, a Db/db type 2 diabetes mouse model has more TC-Vascular Endothelium adhesion compared to a normal model. However, BD patients have a lower expression of ICAM-1, VCAM-1, and E-selectin in their tumor tissues. BD-HDL facilitates the adhesion of tumor cells to vascular endothelium by upregulating the expression of ICAM-1 and VCAM-1, thereby promoting the initial progression of breast cancer metastasis. This work indicates a prospective utilization of HDL-based strategies in the treatment of breast cancer patients with type 2 diabetes.

Strain-specific differences in pili formation and the interaction of Corynebacterium diphtheriae with host cells

PubMed Central

2010-01-01

Background Corynebacterium diphtheriae, the causative agent of diphtheria, is well-investigated in respect to toxin production, while little is known about C. diphtheriae factors crucial for colonization of the host. In this study, we investigated strain-specific differences in adhesion, invasion and intracellular survival and analyzed formation of pili in different isolates. Results Adhesion of different C. diphtheriae strains to epithelial cells and invasion of these cells are not strictly coupled processes. Using ultrastructure analyses by atomic force microscopy, significant differences in macromolecular surface structures were found between the investigated C. diphtheriae strains in respect to number and length of pili. Interestingly, adhesion and pili formation are not coupled processes and also no correlation between invasion and pili formation was found. Using RNA hybridization and Western blotting experiments, strain-specific pili expression patterns were observed. None of the studied C. diphtheriae strains had a dramatic detrimental effect on host cell viability as indicated by measurements of transepithelial resistance of Detroit 562 cell monolayers and fluorescence microscopy, leading to the assumption that C. diphtheriae strains might use epithelial cells as an environmental niche supplying protection against antibodies and macrophages. Conclusions The results obtained suggest that it is necessary to investigate various isolates on a molecular level to understand and to predict the colonization process of different C. diphtheriae strains. PMID:20942914

Autophagy promotes degradation of internalized collagen and regulates distribution of focal adhesions to suppress cell adhesion

PubMed Central

Kawano, Shinichi; Esaki, Motohiro; Torisu, Kumiko; Matsuno, Yuichi; Kitazono, Takanari

2017-01-01

ABSTRACT Adhesion of cells to the extracellular matrix (ECM) via focal adhesions (FAs) is crucial for cell survival, migration, and differentiation. Although the regulation of FAs, including by integrins and the ECM, is important to cell behavior, how FAs are regulated is not well known. Autophagy is induced by both cell adhesion and cell detachment. Here, we showed that autophagosomes are located close to internalized collagen and paxillin, which is a well-known marker of FAs. Autophagy-deficient cells showed increased levels of internalized collagen compared with control cells. Moreover, paxillin exhibited a more peripheral distribution and the area of paxillin was increased, and adhesion-induced focal adhesion kinase signaling was impaired and adhesion was enhanced, in autophagy-deficient cells. These results suggest that autophagy suppressed cell adhesion by regulating internalized ECM and FAs. PMID:28970230

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

Adherence of Candida sp. to host tissues and cells as one of its pathogenicity features.

PubMed

Modrzewska, Barbara; Kurnatowski, Piotr

2015-01-01

The ability of Candida sp. cells to adhere to the mucosal surfaces of various host organs as well as synthetic materials is an important pathogenicity feature of those fungi which contributes to the development of infection. This property varies depending on the species of the fungus and is the greatest for C. albicans. The process of adhesion depends on plenty of factors related to the fungal and host cells as well as environmental conditions. The main adhesins present on the fungal cell wall are: Als, Epa, Hwp1, but also Eap1, Sun41, Csh1 and probably Hyr1; for adhesion significant are also secreted aspartyl proteases Sap. Various researchers specify a range of genes which contribute to adhesion, such as: CZF1, EFG1, TUP1, TPK1, TPK2, HGC1, RAS1, RIM101, VPS11, ECM1, CKA2, BCR1, BUD2, RSR1, IRS4, CHS2, SCS7, UBI4, UME6, TEC1 and GAT2. Influence for adherence have also heat shock proteins Hsp70, Mediator Middle domain subunit Med31 and morphological transition. Among factors affecting adhesion related to host cells it is necessary to mention fibronectins and integrins (receptors for Candida sp. adhesins), type of epithelial cells, their morphology and differentiation phase. To a lesser degree influence on adhesion have non-specific factors and environmental conditions.

ROCK Inhibitor Enhances Adhesion and Wound Healing of Human Corneal Endothelial Cells

PubMed Central

Pipparelli, Aurélien; Arsenijevic, Yvan; Thuret, Gilles; Gain, Philippe

2013-01-01

Maintenance of corneal transparency is crucial for vision and depends mainly on the endothelium, a non-proliferative monolayer of cells covering the inner part of the cornea. When endothelial cell density falls below a critical threshold, the barrier and “pump” functions of the endothelium are compromised which results in corneal oedema and loss of visual acuity. The conventional treatment for such severe disorder is corneal graft. Unfortunately, there is a worldwide shortage of donor corneas, necessitating amelioration of tissue survival and storage after harvesting. Recently it was reported that the ROCK inhibitor Y-27632 promotes adhesion, inhibits apoptosis, increases the number of proliferating monkey corneal endothelial cells in vitro and enhance corneal endothelial wound healing both in vitro and in vivo in animal models. Using organ culture human cornea (N = 34), the effect of ROCK inhibitor was evaluated in vitro and ex vivo. Toxicity, corneal endothelial cell density, cell proliferation, apoptosis, cell morphometry, adhesion and wound healing process were evaluated by live/dead assay standard cell counting method, EdU labelling, Ki67, Caspase3, Zo-1 and Actin immunostaining. We demonstrated for the first time in human corneal endothelial cells ex vivo and in vitro, that ROCK inhibitor did not induce any toxicity effect and did not alter cell viability. ROCK inhibitor treatment did not induce human corneal endothelial cells proliferation. However, ROCK inhibitor significantly enhanced adhesion and wound healing. The present study shows that the selective ROCK inhibitor Y-27632 has no effect on human corneal endothelial cells proliferative capacities, but alters cellular behaviours. It induces changes in cell shape, increases cell adhesion and enhances wound healing ex vivo and in vitro. Its absence of toxicity, as demonstrated herein, is relevant for its use in human therapy. PMID:23626771

Material nanosizing effect on living organisms: non-specific, biointeractive, physical size effects

PubMed Central

Watari, Fumio; Takashi, Noriyuki; Yokoyama, Atsuro; Uo, Motohiro; Akasaka, Tsukasa; Sato, Yoshinori; Abe, Shigeaki; Totsuka, Yasunori; Tohji, Kazuyuki

2009-01-01

Nanosizing effects of materials on biological organisms was investigated by biochemical cell functional tests, cell proliferation and animal implantation testing. The increase in specific surface area causes the enhancement of ionic dissolution and serious toxicity for soluble, stimulative materials. This effect originates solely from materials and enhances the same functions as those in a macroscopic size as a catalyst. There are other effects that become prominent, especially for non-soluble, biocompatible materials such as Ti. Particle size dependence showed the critical size for the transition of behaviour is at approximately 100 μm, 10 μm and 200 nm. This effect has its origin in the biological interaction process between both particles and cells/tissue. Expression of superoxide anions, cytokines tumour necrosis factor-α and interleukin-1β from neutrophils was increased with the decrease in particle size and especially pronounced below 10 μm, inducing phagocytosis to cells and inflammation of tissue, although inductively coupled plasma chemical analysis showed no dissolution from Ti particles. Below 200 nm, stimulus decreases, then particles invade into the internal body through the respiratory or digestive systems and diffuse inside the body. Although macroscopic hydroxyapatite, which exhibits excellent osteoconductivity, is not replaced with natural bone, nanoapatite composites induce both phagocytosis of composites by osteoclasts and new bone formation by osteoblasts when implanted in bone defects. The progress of this bioreaction results in the conversion of functions to bone substitution. Although macroscopic graphite is non-cell adhesive, carbon nanotubes (CNTs) are cell adhesive. The adsorption of proteins and nano-meshwork structure contribute to the excellent cell adhesion and growth on CNTs. Non-actuation of the immune system except for a few innate immunity processes gives the non-specific nature to the particle bioreaction and restricts reaction to the size-sensitive phagocytosis. Materials larger than cell size, approximately 10 μm, behave inertly, but those smaller become biointeractive and induce the intrinsic functions of living organisms. This bioreaction process causes the conversion of functions such as from biocompatibility to stimulus in Ti-abraded particles, from non-bone substitutional to bone substitutional in nanoapatite and from non-cell adhesive to cell adhesive CNTs. The insensitive nature permits nanoparticles that are less than 200 nm to slip through body defence systems and invade directly into the internal body. PMID:19364724

Activation of EGF receptor kinase by L1-mediated homophilic cell interactions.

PubMed

Islam, Rafique; Kristiansen, Lars V; Romani, Susana; Garcia-Alonso, Luis; Hortsch, Michael

2004-04-01

Neural cell adhesion molecules (CAMs) are important players during neurogenesis and neurite outgrowth as well as axonal fasciculation and pathfinding. Some of these developmental processes entail the activation of cellular signaling cascades. Pharmacological and genetic evidence indicates that the neurite outgrowth-promoting activity of L1-type CAMs is at least in part mediated by the stimulation of neuronal receptor tyrosine kinases (RTKs), especially FGF and EGF receptors. It has long been suspected that neural CAMs might physically interact with RTKs, but their activation by specific cell adhesion events has not been directly demonstrated. Here we report that gain-of-function conditions of the Drosophila L1-type CAM Neuroglian result in profound sensory axon pathfinding defects in the developing Drosophila wing. This phenotype can be suppressed by decreasing the normal gene dosage of the Drosophila EGF receptor gene. Furthermore, in Drosophila S2 cells, cell adhesion mediated by human L1-CAM results in the specific activation of human EGF tyrosine kinase at cell contact sites and EGF receptors engage in a physical interaction with L1-CAM molecules. Thus L1-type CAMs are able to promote the adhesion-dependent activation of EGF receptor signaling in vitro and in vivo.

Remodeling of adhesion and modulation of mechanical tensile forces during apoptosis in Drosophila epithelium.

PubMed

Teng, Xiang; Qin, Lei; Le Borgne, Roland; Toyama, Yusuke

2017-01-01

Apoptosis is a mechanism of eliminating damaged or unnecessary cells during development and tissue homeostasis. During apoptosis within a tissue, the adhesions between dying and neighboring non-dying cells need to be remodeled so that the apoptotic cell is expelled. In parallel, contraction of actomyosin cables formed in apoptotic and neighboring cells drives cell extrusion. To date, the coordination between the dynamics of cell adhesion and the progressive changes in tissue tension around an apoptotic cell is not fully understood. Live imaging of histoblast expansion, which is a coordinated tissue replacement process during Drosophila metamorphosis, shows remodeling of adherens junctions (AJs) between apoptotic and non-dying cells, with a reduction in the levels of AJ components, including E-cadherin. Concurrently, surrounding tissue tension is transiently released. Contraction of a supra-cellular actomyosin cable, which forms in neighboring cells, brings neighboring cells together and further reshapes tissue tension toward the completion of extrusion. We propose a model in which modulation of tissue tension represents a mechanism of apoptotic cell extrusion. © 2017. Published by The Company of Biologists Ltd.

E-Selectin Mediates Stem Cell Adhesion and Formation of Blood Vessels in a Murine Model of Infantile Hemangioma

PubMed Central

Smadja, David M.; Mulliken, John B.; Bischoff, Joyce

2013-01-01

Hemangioma stem cells (HemSCs) are multipotent cells isolated from infantile hemangioma (IH), which form hemangioma-like lesions when injected subcutaneously into immune-deficient mice. In this murine model, HemSCs are the primary target of corticosteroid, a mainstay therapy for problematic IH. The relationship between HemSCs and endothelial cells that reside in IH is not clearly understood. Adhesive interactions might be critical for the preferential accumulation of HemSCs and/or endothelial cells in the tumor. Therefore, we studied the interactions between HemSCs and endothelial cells (HemECs) isolated from IH surgical specimens. We found that HemECs isolated from proliferating phase IH, but not involuting phase, constitutively express E-selectin, a cell adhesion molecule not present in quiescent endothelial cells. E-selectin was further increased when HemECs were exposed to vascular endothelial growth factor–A or tumor necrosis factor–α. In vitro, HemSC migration and adhesion was enhanced by recombinant E-selectin but not P-selectin; both processes were neutralized by E-selectin–blocking antibodies. E-selectin–positive HemECs also stimulated migration and adhesion of HemSCs. In vivo, neutralizing antibodies to E-selectin strongly inhibited formation of blood vessels when HemSCs and HemECs were co-implanted in Matrigel. These data suggest that endothelial E-selectin could be a major ligand for HemSCs and thereby promote cellular interactions and vasculogenesis in IH. We propose that constitutively expressed E-selectin on endothelial cells in the proliferating phase is one mediator of the stem cell tropism in IH. PMID:23041613

In vitro study on bone formation and surface topography from the standpoint of biomechanics.

PubMed

Kawahara, H; Soeda, Y; Niwa, K; Takahashi, M; Kawahara, D; Araki, N

2004-12-01

Effect of surface topography upon cell-adhesion, -orientation and -differentiation was investigated by in vitro study on cellular responses to titanium substratum with different surface roughness. Cell-shape, -function and -differentiation depending upon the surface topography were clarified by use of bone formative group cells (BFGCs) derived from bone marrow of beagle's femur. BFGCs consisted of hematopoietic stem cells (HSC) and osteogenetic stem cells (OSC). Cell differentiation of BFGCs was expressed and promoted by structural changes of cytoskeleton, and cell-organella, which was caused by mechanical stress with cytoplasmic stretching of cell adhesions to the substratum. Phagocytic monocytes of HSC differentiated to osteomediator cells (OMC) by cytoplasmic stretching with cell adhesion to the substratum. The OMC mediated and promoted cell differentiation from OSC to osteoblast through osteoblastic phenotype cell (OBC) by cell-aggregation of nodules with "pile up" phenomenon of OBC onto OMC. The osteogenesis might be performed by coupling work of both cells, OMC originated from monocyte of HSC and OBC originated from OSC, which were explained by SEM, TEM and fluorescent probe investigation on BFGCs on the test plate of cp titanium plates with different topographies. This osteogenetic process was proved by investigating cell proliferation, DNA contents, cell-adhesion, alkaline phosphatase activity and osteocalcine productivity for cells on the titanium plates with different topographies. The study showed increased osteogenic effects for cells cultured on Ti with increased surface roughness. Possible mechanisms were discussed from a biomechanical perspective.

Collective Signal Processing in Cluster Chemotaxis: Roles of Adaptation, Amplification, and Co-attraction in Collective Guidance

PubMed Central

Camley, Brian A.; Zimmermann, Juliane; Levine, Herbert; Rappel, Wouter-Jan

2016-01-01

Single eukaryotic cells commonly sense and follow chemical gradients, performing chemotaxis. Recent experiments and theories, however, show that even when single cells do not chemotax, clusters of cells may, if their interactions are regulated by the chemoattractant. We study this general mechanism of “collective guidance” computationally with models that integrate stochastic dynamics for individual cells with biochemical reactions within the cells, and diffusion of chemical signals between the cells. We show that if clusters of cells use the well-known local excitation, global inhibition (LEGI) mechanism to sense chemoattractant gradients, the speed of the cell cluster becomes non-monotonic in the cluster’s size—clusters either larger or smaller than an optimal size will have lower speed. We argue that the cell cluster speed is a crucial readout of how the cluster processes chemotactic signals; both amplification and adaptation will alter the behavior of cluster speed as a function of size. We also show that, contrary to the assumptions of earlier theories, collective guidance does not require persistent cell-cell contacts and strong short range adhesion. If cell-cell adhesion is absent, and the cluster cohesion is instead provided by a co-attraction mechanism, e.g. chemotaxis toward a secreted molecule, collective guidance may still function. However, new behaviors, such as cluster rotation, may also appear in this case. Co-attraction and adaptation allow for collective guidance that is robust to varying chemoattractant concentrations while not requiring strong cell-cell adhesion. PMID:27367541

Molecular Basis for Strain Variation in the Saccharomyces cerevisiae Adhesin Flo11p

PubMed Central

Li, Li; Lipke, Peter N.; Dranginis, Anne M.

2016-01-01

ABSTRACT FLO11 encodes a yeast cell wall flocculin that mediates a variety of adhesive phenotypes in Saccharomyces cerevisiae. Flo11p is implicated in many developmental processes, including flocculation, formation of pseudohyphae, agar invasion, and formation of microbial mats and biofilms. However, Flo11p mediates different processes in different yeast strains. To investigate the mechanisms by which FLO11 determines these differences in colony morphology, flocculation, and invasion, we studied gene structure, function, and expression levels. Nonflocculent Saccharomyces cerevisiae Σ1278b cells exhibited significantly higher FLO11 mRNA expression, especially in the stationary phase, than highly flocculent S. cerevisiae var. diastaticus. The two strains varied in cell surface hydrophobicity, and Flo11p contributed significantly to surface hydrophobicity in S. cerevisiae var. diastaticus but not in strain Σ1278b. Sequencing of the FLO11 gene in S. cerevisiae var. diastaticus revealed strain-specific differences, including a 15-amino-acid insertion in the adhesion domain. Flo11p adhesion domains from strain Σ1278b and S. cerevisiae var. diastaticus were expressed and used to coat magnetic beads. The adhesion domain from each strain bound preferentially to homologous cells, and the preferences were independent of the cells in which the adhesion domains were produced. These results are consistent with the idea that strain-specific variations in the amino acid sequences in the adhesion domains cause different Flo11p flocculation activities. The results also imply that strain-specific differences in expression levels, posttranslational modifications, and allelic differences outside the adhesion domains have little effect on flocculation. IMPORTANCE As a nonmotile organism, Saccharomyces cerevisiae employs the cell surface flocculin Flo11/Muc1 as an important means of adapting to environmental change. However, there is a great deal of strain variation in the expression of Flo11-dependent phenotypes, including flocculation. In this study, we investigated the molecular basis of this strain-specific phenotypic variability. Our data indicate that strain-specific differences in the level of flocculation result from significant sequence differences in the FLO11 alleles and do not depend on quantitative differences in FLO11 expression or on surface hydrophobicity. We further have shown that beads coated with amino-terminal domain peptide bind preferentially to homologous cells. These data show that variability in the structure of the Flo11 adhesion domain may thus be an important determinant of membership in microbial communities and hence may drive selection and evolution. PMID:27547826

Changes in E-cadherin rigidity sensing regulate cell adhesion.

PubMed

Collins, Caitlin; Denisin, Aleksandra K; Pruitt, Beth L; Nelson, W James

2017-07-18

Mechanical cues are sensed and transduced by cell adhesion complexes to regulate diverse cell behaviors. Extracellular matrix (ECM) rigidity sensing by integrin adhesions has been well studied, but rigidity sensing by cadherins during cell adhesion is largely unexplored. Using mechanically tunable polyacrylamide (PA) gels functionalized with the extracellular domain of E-cadherin (Ecad-Fc), we showed that E-cadherin-dependent epithelial cell adhesion was sensitive to changes in PA gel elastic modulus that produced striking differences in cell morphology, actin organization, and membrane dynamics. Traction force microscopy (TFM) revealed that cells produced the greatest tractions at the cell periphery, where distinct types of actin-based membrane protrusions formed. Cells responded to substrate rigidity by reorganizing the distribution and size of high-traction-stress regions at the cell periphery. Differences in adhesion and protrusion dynamics were mediated by balancing the activities of specific signaling molecules. Cell adhesion to a 30-kPa Ecad-Fc PA gel required Cdc42- and formin-dependent filopodia formation, whereas adhesion to a 60-kPa Ecad-Fc PA gel induced Arp2/3-dependent lamellipodial protrusions. A quantitative 3D cell-cell adhesion assay and live cell imaging of cell-cell contact formation revealed that inhibition of Cdc42, formin, and Arp2/3 activities blocked the initiation, but not the maintenance of established cell-cell adhesions. These results indicate that the same signaling molecules activated by E-cadherin rigidity sensing on PA gels contribute to actin organization and membrane dynamics during cell-cell adhesion. We hypothesize that a transition in the stiffness of E-cadherin homotypic interactions regulates actin and membrane dynamics during initial stages of cell-cell adhesion.

Effects of macro- versus nanoporous silicon substrates on human aortic endothelial cell behavior

PubMed Central

2014-01-01

Human aortic endothelial cells play a key role in the pathogenesis of atherosclerosis, which is a common, progressive, and multifactorial disease that is the clinical endpoint of an inflammatory process and endothelial dysfunction. Study and development of new therapies against cardiovascular disease must be tested in vitro cell models, prior to be evaluated in vivo. To this aim, new cell culture platforms are developed that allow cells to grow and respond to their environment in a realistic manner. In this work, the cell adhesion and morphology of endothelial cells are investigated on functionalized porous silicon substrates with two different pore size configurations: macroporous and nanoporous silicon. Herein, we modified the surfaces of porous silicon substrates by aminopropyl triethoxysilane, and we studied how different pore geometries induced different cellular response in the cell morphology and adhesion. The cell growth over the surface of porous silicon becomes an attractive field, especially for medical applications. Surface properties of the biomaterial are associated with cell adhesion and as well as, with proliferation, migration and differentiation. PMID:25246859

There are four dynamically and functionally distinct populations of E-cadherin in cell junctions

PubMed Central

Erami, Zahra; Timpson, Paul; Yao, Wu; Zaidel-Bar, Ronen; Anderson, Kurt I.

2015-01-01

ABSTRACT E-cadherin is a trans-membrane tumor suppressor responsible for epithelial cell adhesion. E-cadherin forms adhesive clusters through combined extra-cellular cis- and trans-interactions and intracellular interaction with the actin cytoskeleton. Here we identify four populations of E-cadherin within cell junctions based on the molecular interactions which determine their mobility and adhesive properties. Adhesive and non-adhesive populations of E-cadherin each consist of mobile and immobile fractions. Up to half of the E-cadherin immobilized in cell junctions is non-adhesive. Incorporation of E-cadherin into functional adhesions require all three adhesive interactions, with deletion of any one resulting in loss of effective cell-cell adhesion. Interestingly, the only interaction which could independently slow the diffusion of E-cadherin was the tail-mediated intra-cellular interaction. The adhesive and non-adhesive mobile fractions of E-cadherin can be distinguished by their sensitivity to chemical cross-linking with adhesive clusters. Our data define the size, mobility, and adhesive properties of four distinct populations of E-cadherin within cell junctions, and support association with the actin cytoskeleton as the first step in adhesion formation. PMID:26471767

Junctional adhesion molecule-C promotes metastatic potential of HT1080 human fibrosarcoma.

PubMed

Fuse, Chiaki; Ishida, Yuuki; Hikita, Tomoya; Asai, Tomohiro; Oku, Naoto

2007-03-16

The junctional adhesion molecule (JAM) family is a key molecule in a process called transendothelial migration or diapedesis. Here, we report implications of JAM-C in cancer metastasis. We first determined the mRNA expression of JAMs in 19 kinds of cancer cell lines. JAM-C was expressed in most of tumors having potent metastatic properties. Especially in murine K-1735 melanoma cell lines, the highly metastatic sublines (M2 and X21) strongly expressed JAM-C when compared with the poorly metastatic ones (C-10 and C23). Next, we investigated the role of JAM-C in cancer metastasis by using human JAM-C (hJAM-C) gene-transfected HT1080 fibrosarcoma cells. In comparison with mock-transfected HT1080 cells, these cells showed a significant increase in the adhesion to various extracellular substrates and the invasion across a Matrigel-coated membrane. The knockdown of hJAM-C using small interfering RNA resulted in the suppression of both the adhesion and the invasion of HT1080 cells, suggesting that endogenous hJAM-C might be involved in tumor metastasis. Finally, we studied the role of hJAM-C in an in vivo experimental metastatic model. The results showed that the overexpression of hJAM-C in HT1080 cells significantly decreased the life spans of the tumorbearing mice. In contrast, the knockdown of hJAM-C in HT1080 cells suppressed the weight gain of the lungs with metastatic colonies. We conclude that the expression of JAM-C promotes metastasis by enhancing both the adhesion of cancer cells to extracellular matrices and the subsequent invasion.

Proliferation and osteogenic differentiation of rat BMSCs on a novel Ti/SiC metal matrix nanocomposite modified by friction stir processing

PubMed Central

Zhu, Chenyuan; Lv, Yuting; Qian, Chao; Qian, Haixin; Jiao, Ting; Wang, Liqiang; Zhang, Fuqiang

2016-01-01

The aims of this study were to fabricate a novel titanium/silicon carbide (Ti/SiC) metal matrix nanocomposite (MMNC) by friction stir processing (FSP) and to investigate its microstructure and mechanical properties. In addition, the adhesion, proliferation and osteogenic differentiation of rat bone marrow stromal cells (BMSCs) on the nanocomposite surface were investigated. The MMNC microstructure was observed by both scanning and transmission electron microscopy. Mechanical properties were characterized by nanoindentation and Vickers hardness testing. Integrin β1 immunofluorescence, cell adhesion, and MTT assays were used to evaluate the effects of the nanocomposite on cell adhesion and proliferation. Osteogenic and angiogenic differentiation were evaluated by alkaline phosphatase (ALP) staining, ALP activity, PCR and osteocalcin immunofluorescence. The observed microstructures and mechanical properties clearly indicated that FSP is a very effective technique for modifying Ti/SiC MMNC to contain uniformly distributed nanoparticles. In the interiors of recrystallized grains, characteristics including twins, fine recrystallized grains, and dislocations formed concurrently. Adhesion, proliferation, and osteogenic and angiogenic differentiation of rat BMSCs were all enhanced on the novel Ti/SiC MMNC surface. In conclusion, nanocomposites modified using FSP technology not only have superior mechanical properties under stress-bearing conditions but also provide improved surface and physicochemical properties for cell attachment and osseointegration. PMID:27958394

Diverse roles of integrin receptors in articular cartilage.

PubMed

Shakibaei, M; Csaki, C; Mobasheri, A

2008-01-01

Integrins are heterodimeric integral membrane proteins made up of alpha and beta subunits. At least eighteen alpha and eight beta subunit genes have been described in mammals. Integrin family members are plasma membrane receptors involved in cell adhesion and active as intra- and extracellular signalling molecules in a variety of processes including embryogenesis, hemostasis, tissue repair, immune response and metastatic spread of tumour cells. Integrin beta 1 (beta1-integrin), the protein encoded by the ITGB1 gene (also known as CD29 and VLAB), is a multi-functional protein involved in cell-matrix adhesion, cell signalling, cellular defense, cell adhesion, protein binding, protein heterodimerisation and receptor-mediated activity. It is highly expressed in the human body (17.4 times higher than the average gene in the last updated revision of the human genome). The extracellular matrix (ECM) of articular cartilage is a unique environment. Interactions between chondrocytes and the ECM regulate many biological processes important to homeostasis and repair of articular cartilage, including cell attachment, growth, differentiation and survival. The beta1-integrin family of cell surface receptors appears to play a major role in mediating cell-matrix interactions that are important in regulating these fundamental processes. Chondrocyte mechanoreceptors have been proposed to incorporate beta1-integrins and mechanosensitive ion channels which link with key ECM, cytoskeletal and signalling proteins to maintain the chondrocyte phenotype, prevent chondrocyte apoptosis and regulate chondrocyte-specific gene expression. This review focuses on the expression and function of beta1-integrins in articular chondrocytes, its role in the unique biology of these cells and its distribution in cartilage.

Extravasation of adhering vesicles

NASA Astrophysics Data System (ADS)

Tordeux, C.; Fournier, J.-B.

2002-12-01

We study how the passage of lipid vesicles through a small pore can be induced by the difference in non-specific adhesion energy between the two sides of the substrate bearing the pore. This process is inspired from the extravasation of cells or liposomes from blood vessels, which involves adhesion binders. We study the adhesion-dominated regime and we show that the passage of a vesicle of volume V and area A is selective in terms of the reduced volume v ~ V/A3/2. Extravasation occurs for adhesion ratios of order unity. We also consider the possibility of pressure-induced extravasation in the presence of adhesion. Finally, we propose a micro-device based on adhesion-induced extravasation, which is designed to sort vesicles according to their deflatedness.

Materials from Mussel-Inspired Chemistry for Cell and Tissue Engineering Applications.

PubMed

Madhurakkat Perikamana, Sajeesh Kumar; Lee, Jinkyu; Lee, Yu Bin; Shin, Young Min; Lee, Esther J; Mikos, Antonios G; Shin, Heungsoo

2015-09-14

Current advances in biomaterial fabrication techniques have broadened their application in different realms of biomedical engineering, spanning from drug delivery to tissue engineering. The success of biomaterials depends highly on the ability to modulate cell and tissue responses, including cell adhesion, as well as induction of repair and immune processes. Thus, most recent approaches in the field have concentrated on functionalizing biomaterials with different biomolecules intended to evoke cell- and tissue-specific reactions. Marine mussels produce mussel adhesive proteins (MAPs), which help them strongly attach to different surfaces, even under wet conditions in the ocean. Inspired by mussel adhesiveness, scientists discovered that dopamine undergoes self-polymerization at alkaline conditions. This reaction provides a universal coating for metals, polymers, and ceramics, regardless of their chemical and physical properties. Furthermore, this polymerized layer is enriched with catechol groups that enable immobilization of primary amine or thiol-based biomolecules via a simple dipping process. Herein, this review explores the versatile surface modification techniques that have recently been exploited in tissue engineering and summarizes polydopamine polymerization mechanisms, coating process parameters, and effects on substrate properties. A brief discussion of polydopamine-based reactions in the context of engineering various tissue types, including bone, blood vessels, cartilage, nerves, and muscle, is also provided.

Correlation between E-cadherin-regulated cell adhesion and human osteosarcoma MG-63 cell anoikis.

PubMed

Lin, Ding-Sheng; Cai, Le-Yi; Ding, Jian; Gao, Wei-Yang

2014-01-01

The aim of this study was to investigate the relationship between cell adhesion and anoikis evasion among human osteosarcoma cells (MG-63), and to further study the molecular mechanisms. Human osteosarcoma cells (MG-63) were assessed for apoptosis, and caspase-3, E-cadherin and β-catenin expression in EDTA and control non-EDTA groups. MG-63 cells were predominantly aggregated when in suspension, and the suspended cells were more dispersed in the EDTA group. Following culture in suspension for 24 h, 48 h, or 72 h, the rates of apoptosis were 34.88%±3.64%, 59.3%±7.22% and 78.5%±5.21% in the experimental group and 7.34%±2.13%, 14.7%±3.69%, and 21.4%±3.60% in the control group, respectively. Caspase-3 expression progressively increased and E-cadherin and β-catenin were decreased in the experimental group, whereas there was no change in the control group. MG-63 cells could avoid anoikis through cell adhesion, and E-cadherin might play a role in this process.

Improved single-cell culture achieved using micromolding in capillaries technology coupled with poly (HEMA).

PubMed

Ye, Fang; Jiang, Jin; Chang, Honglong; Xie, Li; Deng, Jinjun; Ma, Zhibo; Yuan, Weizheng

2015-07-01

Cell studies at the single-cell level are becoming more and more critical for understanding the complex biological processes. Here, we present an optimization study investigating the positioning of single cells using micromolding in capillaries technology coupled with the cytophobic biomaterial poly (2-hydroxyethyl methacrylate) (poly (HEMA)). As a cytophobic biomaterial, poly (HEMA) was used to inhibit cells, whereas the glass was used as the substrate to provide a cell adhesive background. The poly (HEMA) chemical barrier was obtained using micromolding in capillaries, and the microchannel networks used for capillarity were easily achieved by reversibly bonding the polydimethylsiloxane mold and the glass. Finally, discrete cell adhesion regions were presented on the glass surface. This method is facile and low cost, and the reagents are commercially available. We validated the cytophobic abilities of the poly (HEMA), optimized the channel parameters for higher quality and more stable poly (HEMA) patterns by investigating the effects of changing the aspect ratio and the width of the microchannel on the poly (HEMA) grid pattern, and improved the single-cell occupancy by optimizing the dimensions of the cell adhesion regions.

Spatiotemporal distribution of different extracellular polymeric substances and filamentation mediate Xylella fastidiosa adhesion and biofilm formation

PubMed Central

Janissen, Richard; Murillo, Duber M.; Niza, Barbara; Sahoo, Prasana K.; Nobrega, Marcelo M.; Cesar, Carlos L.; Temperini, Marcia L. A.; Carvalho, Hernandes F.; de Souza, Alessandra A.; Cotta, Monica A.

2015-01-01

Microorganism pathogenicity strongly relies on the generation of multicellular assemblies, called biofilms. Understanding their organization can unveil vulnerabilities leading to potential treatments; spatially and temporally-resolved comprehensive experimental characterization can provide new details of biofilm formation, and possibly new targets for disease control. Here, biofilm formation of economically important phytopathogen Xylella fastidiosa was analyzed at single-cell resolution using nanometer-resolution spectro-microscopy techniques, addressing the role of different types of extracellular polymeric substances (EPS) at each stage of the entire bacterial life cycle. Single cell adhesion is caused by unspecific electrostatic interactions through proteins at the cell polar region, where EPS accumulation is required for more firmly-attached, irreversibly adhered cells. Subsequently, bacteria form clusters, which are embedded in secreted loosely-bound EPS, and bridged by up to ten-fold elongated cells that form the biofilm framework. During biofilm maturation, soluble EPS forms a filamentous matrix that facilitates cell adhesion and provides mechanical support, while the biofilm keeps anchored by few cells. This floating architecture maximizes nutrient distribution while allowing detachment upon larger shear stresses; it thus complies with biological requirements of the bacteria life cycle. Using new approaches, our findings provide insights regarding different aspects of the adhesion process of X. fastidiosa and biofilm formation. PMID:25891045

Spatiotemporal distribution of different extracellular polymeric substances and filamentation mediate Xylella fastidiosa adhesion and biofilm formation.

PubMed

Janissen, Richard; Murillo, Duber M; Niza, Barbara; Sahoo, Prasana K; Nobrega, Marcelo M; Cesar, Carlos L; Temperini, Marcia L A; Carvalho, Hernandes F; de Souza, Alessandra A; Cotta, Monica A

2015-04-20

Microorganism pathogenicity strongly relies on the generation of multicellular assemblies, called biofilms. Understanding their organization can unveil vulnerabilities leading to potential treatments; spatially and temporally-resolved comprehensive experimental characterization can provide new details of biofilm formation, and possibly new targets for disease control. Here, biofilm formation of economically important phytopathogen Xylella fastidiosa was analyzed at single-cell resolution using nanometer-resolution spectro-microscopy techniques, addressing the role of different types of extracellular polymeric substances (EPS) at each stage of the entire bacterial life cycle. Single cell adhesion is caused by unspecific electrostatic interactions through proteins at the cell polar region, where EPS accumulation is required for more firmly-attached, irreversibly adhered cells. Subsequently, bacteria form clusters, which are embedded in secreted loosely-bound EPS, and bridged by up to ten-fold elongated cells that form the biofilm framework. During biofilm maturation, soluble EPS forms a filamentous matrix that facilitates cell adhesion and provides mechanical support, while the biofilm keeps anchored by few cells. This floating architecture maximizes nutrient distribution while allowing detachment upon larger shear stresses; it thus complies with biological requirements of the bacteria life cycle. Using new approaches, our findings provide insights regarding different aspects of the adhesion process of X. fastidiosa and biofilm formation.

Heterogeneity of Focal Adhesions and Focal Contacts in Motile Fibroblasts.

PubMed

Gladkikh, Aleena; Kovaleva, Anastasia; Tvorogova, Anna; Vorobjev, Ivan A

2018-01-01

Cell-extracellular matrix (ECM) adhesion is an important property of virtually all cells in multicellular organisms. Cell-ECM adhesion studies, therefore, are very significant both for biology and medicine. Over the last three decades, biomedical studies resulted in a tremendous advance in our understanding of the molecular basis and functions of cell-ECM adhesion. Based on morphological and molecular criteria, several different types of model cell-ECM adhesion structures including focal adhesions, focal complexes, fibrillar adhesions, podosomes, and three-dimensional matrix adhesions have been described. All the subcellular structures that mediate cell-ECM adhesion are quite heterogeneous, often varying in size, shape, distribution, dynamics, and, to a certain extent, molecular constituents. The morphological "plasticity" of cell-ECM adhesion perhaps reflects the needs of cells to sense, adapt, and respond to a variety of extracellular environments. In addition, cell type (e.g., differentiation status, oncogenic transformation, etc.) often exerts marked influence on the structure of cell-ECM adhesions. Although molecular, genetic, biochemical, and structural studies provide important maps or "snapshots" of cell-ECM adhesions, the area of research that is equally valuable is to study the heterogeneity of FA subpopulations within cells. Recently time-lapse observations on the FA dynamics become feasible, and behavior of individual FA gives additional information on cell-ECM interactions. Here we describe a robust method of labeling of FA using plasmids with fluorescent markers for paxillin and vinculin and quantifying the morphological and dynamical parameters of FA.

Binding constants of membrane-anchored receptors and ligands depend strongly on the nanoscale roughness of membranes.

PubMed

Hu, Jinglei; Lipowsky, Reinhard; Weikl, Thomas R

2013-09-17

Cell adhesion and the adhesion of vesicles to the membranes of cells or organelles are pivotal for immune responses, tissue formation, and cell signaling. The adhesion processes depend sensitively on the binding constant of the membrane-anchored receptor and ligand proteins that mediate adhesion, but this constant is difficult to measure in experiments. We have investigated the binding of membrane-anchored receptor and ligand proteins with molecular dynamics simulations. We find that the binding constant of the anchored proteins strongly decreases with the membrane roughness caused by thermally excited membrane shape fluctuations on nanoscales. We present a theory that explains the roughness dependence of the binding constant for the anchored proteins from membrane confinement and that relates this constant to the binding constant of soluble proteins without membrane anchors. Because the binding constant of soluble proteins is readily accessible in experiments, our results provide a useful route to compute the binding constant of membrane-anchored receptor and ligand proteins.

Allosteric Regulation of E-Cadherin Adhesion.

PubMed

Shashikanth, Nitesh; Petrova, Yuliya I; Park, Seongjin; Chekan, Jillian; Maiden, Stephanie; Spano, Martha; Ha, Taekjip; Gumbiner, Barry M; Leckband, Deborah E

2015-08-28

Cadherins are transmembrane adhesion proteins that maintain intercellular cohesion in all tissues, and their rapid regulation is essential for organized tissue remodeling. Despite some evidence that cadherin adhesion might be allosterically regulated, testing of this has been hindered by the difficulty of quantifying altered E-cadherin binding affinity caused by perturbations outside the ectodomain binding site. Here, measured kinetics of cadherin-mediated intercellular adhesion demonstrated quantitatively that treatment with activating, anti-E-cadherin antibodies or the dephosphorylation of a cytoplasmic binding partner, p120(ctn), increased the homophilic binding affinity of E-cadherin. Results obtained with Colo 205 cells, which express inactive E-cadherin and do not aggregate, demonstrated that four treatments, which induced Colo 205 aggregation and p120(ctn) dephosphorylation, triggered quantitatively similar increases in E-cadherin affinity. Several processes can alter cell aggregation, but these results directly demonstrated the allosteric regulation of cell surface E-cadherin by p120(ctn) dephosphorylation. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Migration of Toxoplasma gondii–Infected Dendritic Cells across Human Retinal Vascular Endothelium

PubMed Central

Furtado, João M.; Bharadwaj, Arpita S.; Ashander, Liam M.; Olivas, Antoinette; Smith, Justine R.

2012-01-01

Purpose. Toxoplasma gondii, the parasite responsible for ocular toxoplasmosis, accesses the retina from the bloodstream. We investigated the dendritic cell as a potential taxi for T. gondii tachyzoites moving across the human retinal endothelium, and examined the participation of adhesion molecules and chemokines in this process. Methods. CD14-positive monocytes were isolated from human peripheral blood by antibody-mediated cell enrichment, and cultured in granulocyte-macrophage colony-stimulating factor and interleukin-4 to generate dendritic cells. Transmigration assays were performed over 18 hours in transwells seeded with human retinal endothelial cells and using dendritic cells exposed to laboratory or natural strains of T. gondii tachyzoites. Parasites were tagged with yellow fluorescent protein to verify infection. In some experiments, endothelial monolayers were preincubated with antibody directed against adhesion molecules, or chemokine was added to lower chambers of transwells. Results. Human monocyte–derived dendritic cell preparations infected with laboratory or natural strain T. gondii tachyzoites transmigrated in larger numbers across simulated human retinal endothelium than uninfected dendritic cells (P ≤ 0.0004 in 5 of 6 experiments). Antibody blockade of intercellular adhesion molecule (ICAM)–1, vascular cell adhesion molecule (VCAM)–1, and activated leukocyte cell adhesion molecule (ALCAM) inhibited transmigration (P ≤ 0.007), and CCL21 or CXCL10 increased transmigration (P ≤ 0.031). Conclusions. Transmigration of human dendritic cells across retinal endothelium is increased following infection with T. gondii. Movement may be impacted by locally produced chemokines and is mediated in part by ICAM-1, VCAM-1, and ALCAM. These findings have implications for development of novel therapeutics aimed at preventing retinal infection by T. gondii. PMID:22952125

Expression of metastasis suppressor BRMS1 in breast cancer cells results in a marked delay in cellular adhesion to matrix

USDA-ARS?s Scientific Manuscript database

Metastatic dissemination is a multi-step process that depends on cancer cells’ ability to respond to microenvironmental cues by adapting adhesion abilities and undergoing cytoskeletal rearrangement. Breast Cancer Metastasis Suppressor 1 (BRMS1) affects several steps of the metastatic cascade: it dec...

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

Borrelia burgdorferi upregulates the adhesion molecules E-selectin, P-selectin, ICAM-1 and VCAM-1 on mouse endothelioma cells in vitro.

PubMed

Böggemeyer, E; Stehle, T; Schaible, U E; Hahne, M; Vestweber, D; Simon, M M

1994-06-01

In order to obtain more information on processes leading to Borrelia burgdorferi-induced inflammation in the host, we have developed an in vitro model to study the upregulation of cell surface expression of adhesion molecules on endothelial cells by spirochetes. A mouse endothelioma cell line, derived from brain capillaries, bEnd3, was used as indicator population. bEnd3 cells were incubated with preparations of viable, inactivated or sonicated spirochetes and the expression of E-selectin, P-selectin, ICAM-1 and VCAM-1 was monitored by immunocytochemistry and quantified by cell surface ELISA. We show that all three spirochetal preparations are able to upregulate cell surface expression of E-selectin, P-selectin, ICAM-1 and VCAM-1 on bEnd 3 cells in a dose-dependent manner. The kinetics of cell surface expression of the individual adhesion molecules in the presence of Borrelia burgdorferi showed maxima at about 50 h of incubation or later; this was distinct from results obtained with sonicated-preparations of Escherichia coli bacteria or with enterobacterial LPS where peak expression was observed between 4 h and 16 h. The fact that Borrelia burgdorferi does not contain conventional LPS suggests that the mode of induction of adhesion molecules on endothelial cells is influenced by the phenotype of bacteria. At the peak of spirochete-induced cell surface expression of adhesion molecules (approximately 50 h), bEnd3 cells were found to bind cells of a VLA-4+ B lymphoma line (L1-2) much more efficiently than untreated control cells. The binding of L1-2 cells to presensitized bEnd3 cells was significantly inhibited (more than 75%) in the presence of monoclonal antibodies to both VLA-4 and its endothelial counterreceptor VCAM-1. These findings demonstrate that Borrelia burgdorferi organisms are able to induce functionally active adhesion molecules on endothelial cells in vitro and suggest that E-selectin, P-selectin, ICAM-1 and VCAM-1 play an important role in the pathogenesis of spirochetal infection.

Roles of cell-cell adhesion-dependent tyrosine phosphorylation of Gab-1.

PubMed

Shinohara, M; Kodama, A; Matozaki, T; Fukuhara, A; Tachibana, K; Nakanishi, H; Takai, Y

2001-06-01

Gab-1 is a multiple docking protein that is tyrosine phosphorylated by receptor tyrosine kinases such as c-Met, hepatocyte growth factor/scatter factor receptor, and epidermal growth factor receptor. We have now demonstrated that cell-cell adhesion also induces marked tyrosine phosphorylation of Gab-1 and that disruption of cell-cell adhesion results in its dephosphorylation. An anti-E-cadherin antibody decreased cell-cell adhesion-dependent tyrosine phosphorylation of Gab-1, whereas the expression of E-cadherin specifically induced tyrosine phosphorylation of Gab-1. A relatively selective inhibitor of Src family kinases reduced cell-cell adhesion-dependent tyrosine phosphorylation of Gab-1, whereas expression of a dominant-negative mutant of Csk increased it. Disruption of cell-cell adhesion, which reduced tyrosine phosphorylation of Gab-1, also reduced the activation of mitogen-activated protein kinase and Akt in response to cell-cell adhesion. These results indicate that E-cadherin-mediated cell-cell adhesion induces tyrosine phosphorylation by a Src family kinase of Gab-1, thereby regulating the activation of Ras/MAP kinase and phosphatidylinositol 3-kinase/Akt cascades.

Structural Analysis and Application of n-Alkyl Cyanoacrylate Surgical Adhesives to the Fixation of Meshes for Hernia Repair.

PubMed

Fernández-Gutiérrez, Mar; Rodriguez-Mancheño, Marta; Pérez-Köhler, Bárbara; Pascual, Gemma; Bellón, Juan Manuel; Román, Julio San

2016-12-01

The article deals with a comparative analysis of the parameters of the polymerization in physiological conditions of three commercially available alkyl cyanoacrylates, n-butyl cyanoacrylate (GLUBRAN 2), n-hexyl cyanoacrylate (IFABOND), and n-octyl cyanoacrylate (EVOBOND), the cell behavior of the corresponding polymers and the application of these adhesives in the fixation of surgical polypropylene meshes for hernia repair in an animal model of rabbits. The results obtained demonstrate that the curing process depends on the nature of the alkyl residue of the ester group of cyanoacrylate molecules, being the heat of polymerization lower for the octyl derivative in comparison with the hexyl and butyl, and reaching a maximum temperature of 35 °C after a time of mixing with physiological fluids of 60-70 s. The cell behavior demonstrates that the three systems do not present toxicity for fibroblasts and low adhesion of cells, which is a positive result for application as tissue adhesives, especially for the fixation of abdominal polypropylene meshes for hernia repair. The animal experimentation indicates the excellent tolerance of the meshes fixed with the cyanoacrylic adhesives, during at least a period of 90 d, and guarantees a good adhesion for the application of hernia repair meshes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Changes in E-cadherin rigidity sensing regulate cell adhesion

PubMed Central

Collins, Caitlin; Pruitt, Beth L.; Nelson, W. James

2017-01-01

Mechanical cues are sensed and transduced by cell adhesion complexes to regulate diverse cell behaviors. Extracellular matrix (ECM) rigidity sensing by integrin adhesions has been well studied, but rigidity sensing by cadherins during cell adhesion is largely unexplored. Using mechanically tunable polyacrylamide (PA) gels functionalized with the extracellular domain of E-cadherin (Ecad-Fc), we showed that E-cadherin–dependent epithelial cell adhesion was sensitive to changes in PA gel elastic modulus that produced striking differences in cell morphology, actin organization, and membrane dynamics. Traction force microscopy (TFM) revealed that cells produced the greatest tractions at the cell periphery, where distinct types of actin-based membrane protrusions formed. Cells responded to substrate rigidity by reorganizing the distribution and size of high-traction-stress regions at the cell periphery. Differences in adhesion and protrusion dynamics were mediated by balancing the activities of specific signaling molecules. Cell adhesion to a 30-kPa Ecad-Fc PA gel required Cdc42- and formin-dependent filopodia formation, whereas adhesion to a 60-kPa Ecad-Fc PA gel induced Arp2/3-dependent lamellipodial protrusions. A quantitative 3D cell–cell adhesion assay and live cell imaging of cell–cell contact formation revealed that inhibition of Cdc42, formin, and Arp2/3 activities blocked the initiation, but not the maintenance of established cell–cell adhesions. These results indicate that the same signaling molecules activated by E-cadherin rigidity sensing on PA gels contribute to actin organization and membrane dynamics during cell–cell adhesion. We hypothesize that a transition in the stiffness of E-cadherin homotypic interactions regulates actin and membrane dynamics during initial stages of cell–cell adhesion. PMID:28674019

Competitive homing assays to study gut-tropic t cell migration.

PubMed

Villablanca, Eduardo J; Mora, J Rodrigo

2011-03-01

In order to exert their function lymphocytes need to leave the blood and migrate into different tissues in the body. Lymphocyte adhesion to endothelial cells and tissue extravasation is a multistep process controlled by different adhesion molecules (homing receptors) expressed on lymphocytes and their respective ligands (addressions) displayed on endothelial cells (1 2). Even though the function of these adhesion receptors can be partially studied ex vivo, the ultimate test for their physiological relevance is to assess their role during in vivo lymphocyte adhesion and migration. Two complementary strategies have been used for this purpose: intravital microscopy (IVM) and homing experiments. Although IVM has been essential to define the precise contribution of specific adhesion receptors during the adhesion cascade in real time and in different tissues, IVM is time consuming and labor intensive, it often requires the development of sophisticated surgical techniques, it needs prior isolation of homogeneous cell populations and it permits the analysis of only one tissue/organ at any given time. By contrast, competitive homing experiments allow the direct and simultaneous comparison in the migration of two (or even more) cell subsets in the same mouse and they also permit the analysis of many tissues and of a high number of cells in the same experiment. Here we describe the classical competitive homing protocol used to determine the advantage/disadvantage of a given cell type to home to specific tissues as compared to a control cell population. We chose to illustrate the migratory properties of gut-tropic versus non gut-tropic T cells, because the intestinal mucosa is the largest body surface in contact with the external environment and it is also the extra-lymphoid tissue with the best-defined migratory requirements. Moreover, recent work has determined that the vitamin A metabolite all-trans retinoic acid (RA) is the main molecular mechanism responsible for inducing gut-specific adhesion receptors (integrin a4b7and chemokine receptor CCR9) on lymphocytes. Thus, we can readily generate large numbers of gut-tropic and non gut-tropic lymphocytes ex vivoby activating T cells in the presence or absence of RA, respectively, which can be finally used in the competitive homing experiments described here.

Protein Adsorption and Subsequent Fibroblasts Adhesion on Hydroxyapatite Nanocrystals

NASA Astrophysics Data System (ADS)

Tagaya, Motohiro; Ikoma, Toshiyuki; Takemura, Taro; Hanagata, Nobutaka; Yoshioka, Tomohiko; Tanaka, Junzo

2011-10-01

Quartz crystal microbalance with dissipation (QCM-D) technique was employed for protein adsorption and subsequent fibroblast adhesion on hydroxyapatite (HAp) nanocrystals. The pre-adsorption of three proteins (albumin (BSA) or fibronectin (Fn) or collagen (Col)) and subsequent adsorption of fetal bovine serum (FBS), and the adhesion of fibroblasts on the surface were in situ monitored, and evaluated with the frequency shift (Δf) and dissipation energy shift (ΔD), and the viscoelastic change as ΔD-Δf plot. The Col adsorption showed larger Δf and ΔD values compared with BSA or Fn adsorption, and the subsequent FBS adsorption depended on the pre-adsorbed proteins. The ΔD-Δf plot of the cell adhesion also showed the different behaviour on the surfaces, indicating the process affected by cell-protein interactions. The confocal laser scanning microscope images of adherent cells showed the different morphology and pseudopod on the surfaces. The cells adhered on the surfaces modified with Fn and Col had the uniaxially expanded shape with fibrous pseudopods, while those modified with BSA had round shape. The different cell-protein interaction would cause the arrangement of extracellular matrix and cytoskeleton changes at the interfaces.

Nanoengineered surfaces for focal adhesion guidance trigger mesenchymal stem cell self-organization and tenogenesis.

PubMed

Iannone, Maria; Ventre, Maurizio; Formisano, Lucia; Casalino, Laura; Patriarca, Eduardo J; Netti, Paolo A

2015-03-11

The initial conditions for morphogenesis trigger a cascade of events that ultimately dictate structure and functions of tissues and organs. Here we report that surface nanopatterning can control the initial assembly of focal adhesions, hence guiding human mesenchymal stem cells (hMSCs) through the process of self-organization and differentiation. This process self-sustains, leading to the development of macroscopic tissues with molecular profiles and microarchitecture reminiscent of embryonic tendons. Therefore, material surfaces can be in principle engineered to set off the hMSC program toward tissuegenesis in a deterministic manner by providing adequate sets of initial environmental conditions.

Nano-hydroxyapatite-coated metal-ceramic composite of iron-tricalcium phosphate: Improving the surface wettability, adhesion and proliferation of mesenchymal stem cells in vitro.

PubMed

Surmeneva, Maria A; Kleinhans, Claudia; Vacun, Gabriele; Kluger, Petra Juliane; Schönhaar, Veronika; Müller, Michaela; Hein, Sebastian Boris; Wittmar, Alexandra; Ulbricht, Mathias; Prymak, Oleg; Oehr, Christian; Surmenev, Roman A

2015-11-01

Thin radio-frequency magnetron sputter deposited nano-hydroxyapatite (HA) films were prepared on the surface of a Fe-tricalcium phosphate (Fe-TCP) bioceramic composite, which was obtained using a conventional powder injection moulding technique. The obtained nano-hydroxyapatite coated Fe-TCP biocomposites (nano-HA-Fe-TCP) were studied with respect to their chemical and phase composition, surface morphology, water contact angle, surface free energy and hysteresis. The deposition process resulted in a homogeneous, single-phase HA coating. The ability of the surface to support adhesion and the proliferation of human mesenchymal stem cells (hMSCs) was studied using biological short-term tests in vitro. The surface of the uncoated Fe-TCP bioceramic composite showed an initial cell attachment after 24h of seeding, but adhesion, proliferation and growth did not persist during 14 days of culture. However, the HA-Fe-TCP surfaces allowed cell adhesion, and proliferation during 14 days. The deposition of the nano-HA films on the Fe-TCP surface resulted in higher surface energy, improved hydrophilicity and biocompatibility compared with the surface of the uncoated Fe-TCP. Furthermore, it is suggested that an increase in the polar component of the surface energy was responsible for the enhanced cell adhesion and proliferation in the case of the nano-HA-Fe-TCP biocomposites. Copyright © 2015 Elsevier B.V. All rights reserved.

MVL-PLA2, a Snake Venom Phospholipase A2, Inhibits Angiogenesis through an Increase in Microtubule Dynamics and Disorganization of Focal Adhesions

PubMed Central

Bazaa, Amine; Pasquier, Eddy; Defilles, Céline; Limam, Ines; Kessentini-Zouari, Raoudha; Kallech-Ziri, Olfa; Battari, Assou El; Braguer, Diane; Ayeb, Mohamed El; Marrakchi, Naziha; Luis, José

2010-01-01

Integrins are essential protagonists of the complex multi-step process of angiogenesis that has now become a major target for the development of anticancer therapies. We recently reported and characterized that MVL-PLA2, a novel phospholipase A2 from Macrovipera lebetina venom, exhibited anti-integrin activity. In this study, we show that MVL-PLA2 also displays potent anti-angiogenic properties. This phospholipase A2 inhibited adhesion and migration of human microvascular-endothelial cells (HMEC-1) in a dose-dependent manner without being cytotoxic. Using Matrigel™ and chick chorioallantoic membrane assays, we demonstrated that MVL-PLA2, as well as its catalytically inactivated form, significantly inhibited angiogenesis both in vitro and in vivo. We have also found that the actin cytoskeleton and the distribution of αvβ3 integrin, a critical regulator of angiogenesis and a major component of focal adhesions, were disturbed after MVL-PLA2 treatment. In order to further investigate the mechanism of action of this protein on endothelial cells, we analyzed the dynamic instability behavior of microtubules in living endothelial cells. Interestingly, we showed that MVL-PLA2 significantly increased microtubule dynamicity in HMEC-1 cells by 40%. We propose that the enhancement of microtubule dynamics may explain the alterations in the formation of focal adhesions, leading to inhibition of cell adhesion and migration. PMID:20405031

Cellular and molecular investigations of the adhesion and mechanics of Listeria monocytogenes

NASA Astrophysics Data System (ADS)

Eskhan, Asma Omar

Atomic force microscopy has been used to quantify the adherence and mechanical properties of an array of L. monocytogenes strains and their surface biopolymers. First, eight L. monocytogenes strains that represented the two major lineages of the species were compared for their adherence and mechanics at cellular and molecular levels. Our results indicated that strains of lineage' II were characterized by higher adhesion and Young's moduli, longer and more rigid surface biopolymers and lower specific and nonspecific forces when compared to lineage' I strains. Additionally, adherence and mechanical properties of eight L. monocytogenes epidemic and environmental strains were probed. Our results pointed to that environmental and epidemic strains representative of a given lineage were similar in their adherence and mechanical properties when investigated at a cellular level. However, when the molecular properties of the strains were considered, epidemic strains were characterized by higher specific and nonspecific forces, shorter, denser and more flexible biopolymers compared to environmental strains. Second, the role of environmental pH conditions of growth on the adhesion and mechanics of a pathogenic L. monocytogenes EGDe was investigated. Our results pointed to a transition in the adhesion energies for cells cultured at pH 7. In addition, when the types of molecular forces that govern the adhesion were quantified using Poisson statistical approach and using a new proposed method, specific hydrogen-bond energies dominated the bacterial adhesion process. Such a finding is instrumental to researchers designing methods to control bacterial adhesion. Similarly, bacterial cells underwent a transition in their mechanical properties. We have shown that cells cultured at pH 7 were the most rigid compared to those cultured in lower or higher pH conditions of growth. Due to transitions observed in adherence and mechanics when cells were cultured at pH 7, we hypothesized that adhesion and mechanics are correlated. To test this hypothesis, nonadhesive and adhesive models of contact mechanics were used to estimate Young's moduli. Our results indicated that the nonadhesive model of contact mechanics estimated 18 % more rigid bacterial cells. Our results thus point to the importance of considering molecular details when investigating bacterial adhesion and mechanics.

Surfing the wave, cycle, life history, and genes/proteins expressed by testicular germ cells. Part 5: intercellular junctions and contacts between germs cells and Sertoli cells and their regulatory interactions, testicular cholesterol, and genes/proteins associated with more than one germ cell generation.

PubMed

Hermo, Louis; Pelletier, R-Marc; Cyr, Daniel G; Smith, Charles E

2010-04-01

In the testis, cell adhesion and junctional molecules permit specific interactions and intracellular communication between germ and Sertoli cells and apposed Sertoli cells. Among the many adhesion family of proteins, NCAM, nectin and nectin-like, catenins, and cadherens will be discussed, along with gap junctions between germ and Sertoli cells and the many members of the connexin family. The blood-testis barrier separates the haploid spermatids from blood borne elements. In the barrier, the intercellular junctions consist of many proteins such as occludin, tricellulin, and claudins. Changes in the expression of cell adhesion molecules are also an essential part of the mechanism that allows germ cells to move from the basal compartment of the seminiferous tubule to the adluminal compartment thus crossing the blood-testis barrier and well-defined proteins have been shown to assist in this process. Several structural components show interactions between germ cells to Sertoli cells such as the ectoplasmic specialization which are more closely related to Sertoli cells and tubulobulbar complexes that are processes of elongating spermatids embedded into Sertoli cells. Germ cells also modify several Sertoli functions and this also appears to be the case for residual bodies. Cholesterol plays a significant role during spermatogenesis and is essential for germ cell development. Lastly, we list genes/proteins that are expressed not only in any one specific generation of germ cells but across more than one generation. Copyright 2009 Wiley-Liss, Inc.

Quantitative comparison of cancer and normal cell adhesion using organosilane monolayer templates: an experimental study on the anti-adhesion effect of green-tea catechins.

PubMed

Sakamoto, Rumi; Kakinuma, Eisuke; Masuda, Kentaro; Takeuchi, Yuko; Ito, Kosaku; Iketaki, Kentaro; Matsuzaki, Takahisa; Nakabayashi, Seiichiro; Yoshikawa, Hiroshi Y; Yamamoto, Hideaki; Sato, Yuko; Tanii, Takashi

2016-09-01

The main constituent of green tea, (-)-Epigallocatechin-3-O-gallate (EGCG), is known to have cancer-specific chemopreventive effects. In the present work, we investigated how EGCG suppresses cell adhesion by comparing the adhesion of human pancreatic cancer cells (AsPC-1 and BxPC-3) and their counterpart, normal human embryonic pancreas-derived cells (1C3D3), in catechin-containing media using organosilane monolayer templates (OMTs). The purpose of this work is (1) to evaluate the quantitativeness in the measurement of cell adhesion with the OMT and (2) to show how green-tea catechins suppress cell adhesion in a cancer-specific manner. For the first purpose, the adhesion of cancer and normal cells was compared using the OMT. The cell adhesion in different type of catechins such as EGCG, (-)-Epicatechin-3-O-gallate (ECG) and (-)-Epicatechin (EC) was also evaluated. The measurements revealed that the anti-adhesion effect of green-tea catechins is cancer-specific, and the order is EGCG≫ECG>EC. The results agree well with the data reported to date, showing the quantitativeness of the new method. For the second purpose, the contact area of cells on the OMT was measured by reflection interference contrast microscopy. The cell-OMT contact area of cancer cells decreases with increasing EGCG concentration, whereas that of normal cells remains constant. The results reveal a twofold action of EGCG on cancer cell adhesion-suppressing cell attachment to a candidate adhesion site and decreasing the contact area of the cells-and validates the use of OMT as a tool for screening cancer cell adhesion.

Studying cytokinesis in Drosophila epithelial tissues.

PubMed

Pinheiro, D; Bellaïche, Y

2017-01-01

Epithelial tissue cohesiveness is ensured through cell-cell junctions that maintain both adhesion and mechanical coupling between neighboring cells. During development, epithelial tissues undergo intensive cell proliferation. Cell division, and particularly cytokinesis, is coupled to the formation of new adhesive contacts, thereby preserving tissue integrity and propagating cell polarity. Remarkably, the geometry of the new interfaces is determined by the combined action of the dividing cell and its neighbors. To further understand the interplay between the dividing cell and its neighbors, as well as the role of cell division for tissue morphogenesis, it is important to analyze cytokinesis in vivo. Here we present methods to perform live imaging of cell division in Drosophila epithelial tissues and discuss some aspects of image processing and analysis. Copyright © 2017 Elsevier Inc. All rights reserved.

Directing Stem Cell Differentiation via Electrochemical Reversible Switching between Nanotubes and Nanotips of Polypyrrole Array.

PubMed

Wei, Yan; Mo, Xiaoju; Zhang, Pengchao; Li, Yingying; Liao, Jingwen; Li, Yongjun; Zhang, Jinxing; Ning, Chengyun; Wang, Shutao; Deng, Xuliang; Jiang, Lei

2017-06-27

Control of stem cell behaviors at solid biointerfaces is critical for stem-cell-based regeneration and generally achieved by engineering chemical composition, topography, and stiffness. However, the influence of dynamic stimuli at the nanoscale from solid biointerfaces on stem cell fate remains unclear. Herein, we show that electrochemical switching of a polypyrrole (Ppy) array between nanotubes and nanotips can alter surface adhesion, which can strongly influence mechanotransduction activation and guide differentiation of mesenchymal stem cells (MSCs). The Ppy array, prepared via template-free electrochemical polymerization, can be reversibly switched between highly adhesive hydrophobic nanotubes and poorly adhesive hydrophilic nanotips through an electrochemical oxidation/reduction process, resulting in dynamic attachment and detachment to MSCs at the nanoscale. Multicyclic attachment/detachment of the Ppy array to MSCs can activate intracellular mechanotransduction and osteogenic differentiation independent of surface stiffness and chemical induction. This smart surface, permitting transduction of nanoscaled dynamic physical inputs into biological outputs, provides an alternative to classical cell culture substrates for regulating stem cell fate commitment. This study represents a general strategy to explore nanoscaled interactions between stem cells and stimuli-responsive surfaces.

Cell adhesion molecules in context

PubMed Central

2011-01-01

Cell adhesion molecules (CAMs) are now known to mediate much more than adhesion between cells and between cells and the extracellular matrix. Work by many researchers has illuminated their roles in modulating activation of molecules such as receptor tyrosine kinases, with subsequent effects on cell survival, migration and process extension. CAMs are also known to serve as substrates for proteases that can create diffusible fragments capable of signaling independently from the CAM. The diversity of interactions is further modulated by membrane rafts, which can co-localize or separate potential signaling partners to affect the likelihood of a given signaling pathway being activated. Given the ever-growing number of known CAMs and the fact that their heterophilic binding in cis or in trans can affect their interactions with other molecules, including membrane-bound receptors, one would predict a wide range of effects attributable to a particular CAM in a particular cell at a particular stage of development. The function(s) of a given CAM must therefore be considered in the context of the history of the cell expressing it and the repertoire of molecules expressed both by that cell and its neighbors. PMID:20948304

Trimethylamine N-oxide in atherogenesis: impairing endothelial self-repair capacity and enhancing monocyte adhesion.

PubMed

Ma, GuoHua; Pan, Bing; Chen, Yue; Guo, CaiXia; Zhao, MingMing; Zheng, LeMin; Chen, BuXing

2017-04-30

Several studies have reported a strong association between high plasma level of trimethylamine N-oxide (TMAO) and atherosclerosis development. However, the exact mechanism underlying this correlation is unknown. In the present study, we try to explore the impact of TMAO on endothelial dysfunction. After TMAO treatment, human umbilical vein endothelial cells (HUVECs) showed significant impairment in cellular proliferation and HUVECs-extracellular matrix (ECM) adhesion compared with control. Likewise, TMAO markedly suppressed HUVECs migration in transwell migration assay and wound healing assay. In addition, we found TMAO up-regulated vascular cell adhesion molecule-1 (VCAM-1) expression, promoted monocyte adherence, activated protein kinase C (PKC) and p-NF-κB. Interestingly, TMAO-stimulated VCAM-1 expression and monocyte adherence were diminished by PKC inhibitor. These results demonstrate that TMAO promotes early pathological process of atherosclerosis by accelerating endothelial dysfunction, including decreasing endothelial self-repair and increasing monocyte adhesion. Furthermore, TMAO-induced monocyte adhesion is partly attributable to activation of PKC/NF-κB/VCAM-1. © 2017 The Author(s).

Adhesion of Photoactive Microalgae to Surfaces is Switchable by Light

NASA Astrophysics Data System (ADS)

Bäumchen, Oliver; Kreis, Christian; Le Blay, Marine; Linne, Christine; Makowski, Marcin

The natural habitats of many microorganisms are confined geometries, such as the interstitial space of rocks and soil, where interactions with interfaces and surfaces are of paramount importance. We performed in vivo force spectroscopy experiments on the unicellular biflagellated microalga Chlamydomonas, a prime model organism in cell- and microbiology, and discovered that the flagella-mediated adhesion to surfaces can be switched on and off by light. Time-resolved micropipette experiments show that the light-switchable adhesiveness of the flagella is a completely reversible process that is based on a redistribution of adhesion-promoting flagella-membrane proteins within seconds. Light-switchable adhesion enables the cell to regulate the transition between planktonic and surface-associated state, which possibly represents a significant biological advantage for photoactive microorganisms. In terms of the colonization of surfaces and the formation of biofilms, the findings might have immediate economic and environmental relevance in biotechnological settings, such as photo-bioreactors for the sustainable production of biofuels.

E-selectin mediates stem cell adhesion and formation of blood vessels in a murine model of infantile hemangioma.

PubMed

Smadja, David M; Mulliken, John B; Bischoff, Joyce

2012-12-01

Hemangioma stem cells (HemSCs) are multipotent cells isolated from infantile hemangioma (IH), which form hemangioma-like lesions when injected subcutaneously into immune-deficient mice. In this murine model, HemSCs are the primary target of corticosteroid, a mainstay therapy for problematic IH. The relationship between HemSCs and endothelial cells that reside in IH is not clearly understood. Adhesive interactions might be critical for the preferential accumulation of HemSCs and/or endothelial cells in the tumor. Therefore, we studied the interactions between HemSCs and endothelial cells (HemECs) isolated from IH surgical specimens. We found that HemECs isolated from proliferating phase IH, but not involuting phase, constitutively express E-selectin, a cell adhesion molecule not present in quiescent endothelial cells. E-selectin was further increased when HemECs were exposed to vascular endothelial growth factor-A or tumor necrosis factor-α. In vitro, HemSC migration and adhesion was enhanced by recombinant E-selectin but not P-selectin; both processes were neutralized by E-selectin-blocking antibodies. E-selectin-positive HemECs also stimulated migration and adhesion of HemSCs. In vivo, neutralizing antibodies to E-selectin strongly inhibited formation of blood vessels when HemSCs and HemECs were co-implanted in Matrigel. These data suggest that endothelial E-selectin could be a major ligand for HemSCs and thereby promote cellular interactions and vasculogenesis in IH. We propose that constitutively expressed E-selectin on endothelial cells in the proliferating phase is one mediator of the stem cell tropism in IH. Copyright © 2012 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

VANGL2 interacts with integrin αv to regulate matrix metalloproteinase activity and cell adhesion to the extracellular matrix.

PubMed

Jessen, Tammy N; Jessen, Jason R

2017-12-15

Planar cell polarity (PCP) proteins are implicated in a variety of morphogenetic processes including embryonic cell migration and potentially cancer progression. During zebrafish gastrulation, the transmembrane protein Vang-like 2 (VANGL2) is required for PCP and directed cell migration. These cell behaviors occur in the context of a fibrillar extracellular matrix (ECM). While it is thought that interactions with the ECM regulate cell migration, it is unclear how PCP proteins such as VANGL2 influence these events. Using an in vitro cell culture model system, we previously showed that human VANGL2 negatively regulates membrane type-1 matrix metalloproteinase (MMP14) and activation of secreted matrix metalloproteinase 2 (MMP2). Here, we investigated the functional relationship between VANGL2, integrin αvβ3, and MMP2 activation. We provide evidence that VANGL2 regulates cell surface integrin αvβ3 expression and adhesion to fibronectin, laminin, and vitronectin. Inhibition of MMP14/MMP2 activity suppressed the cell adhesion defect in VANGL2 knockdown cells. Furthermore, our data show that MMP14 and integrin αv are required for increased proteolysis by VANGL2 knockdown cells. Lastly, we have identified integrin αvβ3 as a novel VANGL2 binding partner. Together, these findings begin to dissect the molecular underpinnings of how VANGL2 regulates MMP activity and cell adhesion to the ECM. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Engagement of αIIbβ3 (GPIIb/IIIa) with ανβ3 Integrin Mediates Interaction of Melanoma Cells with Platelets

PubMed Central

Lonsdorf, Anke S.; Krämer, Björn F.; Fahrleitner, Manuela; Schönberger, Tanja; Gnerlich, Stephan; Ring, Sabine; Gehring, Sarah; Schneider, Stefan W.; Kruhlak, Michael J.; Meuth, Sven G.; Nieswandt, Bernhard; Gawaz, Meinrad; Enk, Alexander H.; Langer, Harald F.

2012-01-01

A mutual relationship exists between metastasizing tumor cells and components of the coagulation cascade. The exact mechanisms as to how platelets influence blood-borne metastasis, however, remain poorly understood. Here, we used murine B16 melanoma cells to observe functional aspects of how platelets contribute to the process of hematogenous metastasis. We found that platelets interfere with a distinct step of the metastasis cascade, as they promote adhesion of melanoma cells to the endothelium in vitro under shear conditions. Constitutively active platelet receptor GPIIb/IIIa (integrin αIIbβ3) expressed on Chinese hamster ovary cells promoted melanoma cell adhesion in the presence of fibrinogen, whereas blocking antibodies to aνβ3 integrin on melanoma cells or to GPIIb/IIIa significantly reduced melanoma cell adhesion to platelets. Furthermore, using intravital microscopy, we observed functional platelet-melanoma cell interactions, as platelet depletion resulted in significantly reduced melanoma cell adhesion to the injured vascular wall in vivo. Using a mouse model of hematogenous metastasis to the lung, we observed decreased metastasis of B16 melanoma cells to the lung by treatment with a mAb blocking the aν subunit of aνβ3 integrin. This effect was significantly reduced when platelets were depleted in vivo. Thus, the engagement of GPIIb/IIIa with aνβ3 integrin interaction mediates tumor cell-platelet interactions and highlights how this interaction is involved in hematogenous tumor metastasis. PMID:22102277

Cellular volume regulation and substrate stiffness modulate the detachment dynamics of adherent cells

NASA Astrophysics Data System (ADS)

Yang, Yuehua; Jiang, Hongyuan

2018-03-01

Quantitative characterizations of cell detachment are vital for understanding the fundamental mechanisms of cell adhesion. Experiments have found that cell detachment shows strong rate dependence, which is mostly attributed to the binding-unbinding kinetics of receptor-ligand bond. However, our recent study showed that the cellular volume regulation can significantly regulate the dynamics of adherent cell and cell detachment. How this cellular volume regulation contributes to the rate dependence of cell detachment remains elusive. Here, we systematically study the role of cellular volume regulation in the rate dependence of cell detachment by investigating the cell detachments of nonspecific adhesion and specific adhesion. We find that the cellular volume regulation and the bond kinetics dominate the rate dependence of cell detachment at different time scales. We further test the validity of the traditional Johnson-Kendall-Roberts (JKR) contact model and the detachment model developed by Wyart and Gennes et al (W-G model). When the cell volume is changeable, the JKR model is not appropriate for both the detachments of convex cells and concave cells. The W-G model is valid for the detachment of convex cells but is no longer applicable for the detachment of concave cells. Finally, we show that the rupture force of adherent cells is also highly sensitive to substrate stiffness, since an increase in substrate stiffness will lead to more associated bonds. These findings can provide insight into the critical role of cell volume in cell detachment and might have profound implications for other adhesion-related physiological processes.

Collisions of deformable cells lead to collective migration

NASA Astrophysics Data System (ADS)

Aranson, Igor; Löber, Jakob; Ziebert, Falko

2015-03-01

Collective migration of eukaryotic cells plays a fundamental role in tissue growth, wound healing and immune response. The motion, arising spontaneously or in response to chemical and mechanical stimuli, is also important for understanding life-threatening pathologies, such as cancer and metastasis formation. We present a phase-field model to describe the movement of many self-organized, interacting cells. The model takes into account the main mechanisms of cell motility - actomyosin dynamics, as well as substrate-mediated and cell-cell adhesion. It predicts that collective cell migration emerges spontaneously as a result of inelastic collisions between neighboring cells: collisions lead to a mutual alignment of the cell velocities and to the formation of coherently-moving multi-cellular clusters. Small cell-to-cell adhesion, in turn, reduces the propensity for large-scale collective migration, while higher adhesion leads to the formation of moving bands. Our study provides valuable insight into biological processes associated with collective cell motility. J. L. acknowledges funding from the German Science Foundation (DFG) within the GRK 1558. F. Z. acknowledges funding from the German Science Foundation (DFG) via Project ZI 1232/2-1. I. S. A. was supported by the US Department of Energy (DOE), Office of.

Opposite Roles of Furin and PC5A in N-Cadherin Processing12

PubMed Central

Maret, Deborah; Sadr, Mohamad Seyed; Sadr, Emad Seyed; Colman, David R; Del Maestro, Rolando F; Seidah, Nabil G

2012-01-01

We recently demonstrated that lack of Furin-processing of the N-cadherin precursor (proNCAD) in highly invasive melanoma and brain tumor cells results in the cell-surface expression of a nonadhesive protein favoring cell migration and invasion in vitro. Quantitative polymerase chain reaction analysis of malignant human brain tumor cells revealed that of all proprotein convertases (PCs) only the levels of Furin and PC5A are modulated, being inversely (Furin) or directly (PC5A) correlated with brain tumor invasive capacity. Intriguingly, the N-terminal sequence following the Furin-activated NCAD site (RQKR↓DW161, mouse nomenclature) reveals a second putative PC-processing site (RIRSDR↓DK189) located in the first extracellular domain. Cleavage at this site would abolish the adhesive functions of NCAD because of the loss of the critical Trp161. This was confirmed upon analysis of the fate of the endogenous prosegment of proNCAD in human malignant glioma cells expressing high levels of Furin and low levels of PC5A (U343) or high levels of PC5A and negligible Furin levels (U251). Cellular analyses revealed that Furin is the best activating convertase releasing an ∼17-kDa prosegment, whereas PC5A is the major inactivating enzyme resulting in the secretion of an ∼20-kDa product. Like expression of proNCAD at the cell surface, cleavage of the NCAD molecule at RIRSDR↓DK189 renders the U251 cancer cells less adhesive to one another and more migratory. Our work modifies the present view on posttranslational processing and surface expression of classic cadherins and clarifies how NCAD possesses a range of adhesive potentials and plays a critical role in tumor progression. PMID:23097623

Silk-based biomaterials functionalized with fibronectin type II promotes cell adhesion.

PubMed

Pereira, Ana Margarida; Machado, Raul; da Costa, André; Ribeiro, Artur; Collins, Tony; Gomes, Andreia C; Leonor, Isabel B; Kaplan, David L; Reis, Rui L; Casal, Margarida

2017-01-01

The objective of this work was to exploit the fibronectin type II (FNII) module from human matrix metalloproteinase-2 as a functional domain for the development of silk-based biopolymer blends that display enhanced cell adhesion properties. The DNA sequence of spider dragline silk protein (6mer) was genetically fused with the FNII coding sequence and expressed in Escherichia coli. The chimeric protein 6mer+FNII was purified by non-chromatographic methods. Films prepared from 6mer+FNII by solvent casting promoted only limited cell adhesion of human skin fibroblasts. However, the performance of the material in terms of cell adhesion was significantly improved when 6mer+FNII was combined with a silk-elastin-like protein in a concentration-dependent behavior. With this work we describe a novel class of biopolymer that promote cell adhesion and potentially useful as biomaterials for tissue engineering and regenerative medicine. This work reports the development of biocompatible silk-based composites with enhanced cell adhesion properties suitable for biomedical applications in regenerative medicine. The biocomposites were produced by combining a genetically engineered silk-elastin-like protein with a genetically engineered spider-silk-based polypeptide carrying the three domains of the fibronectin type II module from human metalloproteinase-2. These composites were processed into free-standing films by solvent casting and characterized for their biological behavior. To our knowledge this is the first report of the exploitation of all three FNII domains as a functional domain for the development of bioinspired materials with improved biological performance. The present study highlights the potential of using genetically engineered protein-based composites as a platform for the development of new bioinspired biomaterials. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

A composite model of the human postcapillary venule for investigation of microvascular leukocyte recruitment

PubMed Central

Lauridsen, Holly M.; Pober, Jordan S.; Gonzalez, Anjelica L.

2014-01-01

Neutrophil extravasation occurs across postcapillary venules, structures composed of endothelial cells (ECs), pericytes (PCs), and basement membrane (BM). We constructed composite models of the human postcapillary venule, combining ECs with PCs or PC-deposited BM, to better study this process. Quiescent and tumor necrosis factor α (TNF-α)-activated composites demonstrated in situ-like expression of cadherins, E-selectin, intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), platelet-endothelial cell adhesion molecule 1 (PECAM-1), CD99, and interleukin 8 (IL-8). After TNF-α activation, the ECs supported greater neutrophil adhesion (66.1 vs. 23.7% of input cells) and transmigration (35.1 vs. 7.20% of input cells) than did the PCs, but the composites behaved comparably (no significant difference) to ECs in both assays. TNF-α-activated EC-conditioned medium (CM) increased transmigration across the PCs, whereas TNF-α-activated PC-CM decreased transmigration across the ECs, and culturing on PC-derived BM decreased both adhesion to and transmigration across the ECs. Anti-very late antigen 4 (VLA-4; on neutrophils) inhibited adhesion to TNF-α-activated composites, but not to ECs alone. Anti-CD99 (expressed on all 3 cell types) inhibited transmigration across the composites (14.5% of control) more than across the ECs (39.0% of control), and venular shear stress reduced transmigration across the ECs (17.3% of static) more than across the composites (36.7% of static). These results provide proof of concept that our composite human EC/PC/BM venular construct can reveal new interactions in the inflammatory cascade.—Lauridsen, H. M., Pober, J. S., Gonzalez, A. L. A composite model of the human postcapillary venule for investigation of microvascular leukocyte recruitment. PMID:24297702

Adhesion of CdTe quantum dots on model membranes and internalization into RBL-2H3 cells.

PubMed

Zhang, Mengmeng; Wei, Xiaoran; Ding, Lei; Hu, Jingtian; Jiang, Wei

2017-06-01

Quantum dots (QDs) have attracted broad attention due to their special optical properties and promising prospect in medical and biological applications. However, the process of QDs on cell membrane is worth further investigations because such process may lead to harmful effects on organisms and also important for QD application. In this study, adhesion of amino- and carboxyl-coated CdTe QDs (A-QDs and C-QDs) on cell membrane and the subsequent internalization are studied using a series of endocytosis-free model membranes, including giant and small unilamellar vesicles, supported lipid bilayers and giant plasma membrane vesicles (GPMVs). The adhered QD amounts on model membranes are quantified by a quartz crystal microbalance. The CdTe QD adhesion on model membranes is governed by electrostatic forces. Positively charged A-QDs adhere on GPMV surface and passively penetrate the plasma membrane via endocytosis-free mechanism, but negatively charged C-QDs cannot. Rat basophilic leukemia (RBL-2H3) cells are exposed to CdTe QDs to monitor the QD internalization process. Both A- and C-QDs are internalized by RBL-2H3 cells mainly via endocytosis. CdTe QDs do not accumulate on the plasma membrane of living cells due to the fast endocytosis and the weakened electrostatic attraction in biological medium, resulting in low chance of passive penetration. The suspended cells after trypsin digestion take more QDs than the adherent cells. A-QDs cause lower cell viability than C-QDs, probably because the approach of positively charged QDs to cells is favored and the smaller aggregates of A-QDs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Adhesion Forces between Lewis(X) Determinant Antigens as Measured by Atomic Force Microscopy.

PubMed

Tromas, C; Rojo, J; de la Fuente, J M; Barrientos, A G; García, R; Penadés, S

2001-01-01

The adhesion forces between individual molecules of Lewis(X) trisaccharide antigen (Le(X) ) have been measured in water and in calcium solution by using atomic force microscopy (AFM, see graph). These results demonstrate the self-recognition capability of this antigen, and reinforce the hypothesis that carbohydrate-carbohydrate interaction could be considered as the first step in the cell-adhesion process in nature. Copyright © 2001 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.

Characterization of the Cell Surface Properties of Drinking Water Pathogens by Microbial Adhesion to Hydrocarbon and Electrophoretic Mobility Measurements

EPA Science Inventory

The surface characteristics of microbial cells directly influence their mobility and behavior within aqueous environments. The cell surface hydrophobicity (CSH) and electrophoretic mobility (EPM) of microbial cells impact a number of interactions and processes including aggregati...

Activation of EGF Receptor Kinase by L1-mediated Homophilic Cell Interactions

PubMed Central

Islam, Rafique; Kristiansen, Lars V.; Romani, Susana; Garcia-Alonso, Luis; Hortsch, Michael

2004-01-01

Neural cell adhesion molecules (CAMs) are important players during neurogenesis and neurite outgrowth as well as axonal fasciculation and pathfinding. Some of these developmental processes entail the activation of cellular signaling cascades. Pharmacological and genetic evidence indicates that the neurite outgrowth-promoting activity of L1-type CAMs is at least in part mediated by the stimulation of neuronal receptor tyrosine kinases (RTKs), especially FGF and EGF receptors. It has long been suspected that neural CAMs might physically interact with RTKs, but their activation by specific cell adhesion events has not been directly demonstrated. Here we report that gain-of-function conditions of the Drosophila L1-type CAM Neuroglian result in profound sensory axon pathfinding defects in the developing Drosophila wing. This phenotype can be suppressed by decreasing the normal gene dosage of the Drosophila EGF receptor gene. Furthermore, in Drosophila S2 cells, cell adhesion mediated by human L1-CAM results in the specific activation of human EGF tyrosine kinase at cell contact sites and EGF receptors engage in a physical interaction with L1-CAM molecules. Thus L1-type CAMs are able to promote the adhesion-dependent activation of EGF receptor signaling in vitro and in vivo. PMID:14718570

Computational Modeling of Tissue Self-Assembly

NASA Astrophysics Data System (ADS)

Neagu, Adrian; Kosztin, Ioan; Jakab, Karoly; Barz, Bogdan; Neagu, Monica; Jamison, Richard; Forgacs, Gabor

As a theoretical framework for understanding the self-assembly of living cells into tissues, Steinberg proposed the differential adhesion hypothesis (DAH) according to which a specific cell type possesses a specific adhesion apparatus that combined with cell motility leads to cell assemblies of various cell types in the lowest adhesive energy state. Experimental and theoretical efforts of four decades turned the DAH into a fundamental principle of developmental biology that has been validated both in vitro and in vivo. Based on computational models of cell sorting, we have developed a DAH-based lattice model for tissues in interaction with their environment and simulated biological self-assembly using the Monte Carlo method. The present brief review highlights results on specific morphogenetic processes with relevance to tissue engineering applications. Our own work is presented on the background of several decades of theoretical efforts aimed to model morphogenesis in living tissues. Simulations of systems involving about 105 cells have been performed on high-end personal computers with CPU times of the order of days. Studied processes include cell sorting, cell sheet formation, and the development of endothelialized tubes from rings made of spheroids of two randomly intermixed cell types, when the medium in the interior of the tube was different from the external one. We conclude by noting that computer simulations based on mathematical models of living tissues yield useful guidelines for laboratory work and can catalyze the emergence of innovative technologies in tissue engineering.

Label-free investigation of the effects of lithium niobate polarization on cell adhesion

NASA Astrophysics Data System (ADS)

Mandracchia, B.; Gennari, O.; Paturzo, M.; Grilli, S.; Ferraro, P.

2017-06-01

The determination of contact area is pivotal to understand how biomaterials properties influence cell adhesion. In particular, the influence of surface charges is well-known but still controversial, especially when new functional materials and methods are introduced. Here, we use for the first time Holographic Total Internal Reflection Microscopy (HoloTIRM) to study the influence of the spontaneous polarization of ferroelectric lithium niobate (LN) on the adhesion properties of fibroblast cells. The selective illumination of a very thin region directly above the substrate, achieved by Total Internal Reflection, provides high-contrast images of the contact regions. Holographic recording, on the other hand, allows for label-free quantitative phase imaging of the contact areas between cells and LN. Phase signal is more sensitive in the first 100nm and, thus more reliable in order to locate focal contacts. This work shows that cells adhering on negatively polarized LN present a significant increase of the contact area in comparison with cells adhering on the positively polarized LN substrate, as well as an intensification of contact vicinity. This confirms the potential of LN as a platform for investigating the role of charges on cellular processes. The similarity of cell adhesion behavior on negatively polarized LN and glass control also confirms the possibility to use LN as an active substrate without impairing cell behavior.

MUC1 extracellular domain confers resistance of epithelial cancer cells to anoikis

PubMed Central

Zhao, Q; Piyush, T; Chen, C; Hollingsworth, M A; Hilkens, J; Rhodes, J M; Yu, L-G

2014-01-01

Anoikis, a special apoptotic process occurring in response to loss of cell adhesion to the extracellular matrix, is a fundamental surveillance process for maintaining tissue homeostasis. Resistance to anoikis characterises cancer cells and is a pre-requisite for metastasis. This study shows that overexpression of the transmembrane mucin protein MUC1 prevents initiation of anoikis in epithelial cancer cells in response to loss of adhesion. We show that this effect is largely attributed to the elongated and heavily glycosylated extracellular domain of MUC1 that protrudes high above the cell membrane and hence prevents activation of the cell surface anoikis-initiating molecules such as integrins and death receptors by providing them a mechanically ‘homing' microenvironment. As overexpression of MUC1 is a common feature of epithelial cancers and as resistance to anoikis is a hallmark of both oncogenic epithelial–mesenchymal transition and metastasis, MUC1-mediated cell resistance to anoikis may represent one of the fundamental regulatory mechanisms in tumourigenesis and metastasis. PMID:25275599

Dynamics of Cell Ensembles on Adhesive Micropatterns: Bridging the Gap between Single Cell Spreading and Collective Cell Migration

PubMed Central

Albert, Philipp J.; Schwarz, Ulrich S.

2016-01-01

The collective dynamics of multicellular systems arise from the interplay of a few fundamental elements: growth, division and apoptosis of single cells; their mechanical and adhesive interactions with neighboring cells and the extracellular matrix; and the tendency of polarized cells to move. Micropatterned substrates are increasingly used to dissect the relative roles of these fundamental processes and to control the resulting dynamics. Here we show that a unifying computational framework based on the cellular Potts model can describe the experimentally observed cell dynamics over all relevant length scales. For single cells, the model correctly predicts the statistical distribution of the orientation of the cell division axis as well as the final organisation of the two daughters on a large range of micropatterns, including those situations in which a stable configuration is not achieved and rotation ensues. Large ensembles migrating in heterogeneous environments form non-adhesive regions of inward-curved arcs like in epithelial bridge formation. Collective migration leads to swirl formation with variations in cell area as observed experimentally. In each case, we also use our model to predict cell dynamics on patterns that have not been studied before. PMID:27054883

Genetic interactions between Drosophila melanogaster Atg1 and paxillin reveal a role for paxillin in autophagosome formation.

PubMed

Chen, Guang-Chao; Lee, Janice Y; Tang, Hong-Wen; Debnath, Jayanta; Thomas, Sheila M; Settleman, Jeffrey

2008-01-01

Autophagy is a conserved cellular process of macromolecule recycling that involves vesicle-mediated degradation of cytoplasmic components. Autophagy plays essential roles in normal cell homeostasis and development, the response to stresses such as nutrient starvation, and contributes to disease processes including cancer and neurodegeneration. Although many of the autophagy components identified from genetic screens in yeast are well conserved in higher organisms, the mechanisms by which this process is regulated in any species are just beginning to be elucidated. In a genetic screen in Drosophila melanogaster, we have identified a link between the focal adhesion protein paxillin and the Atg1 kinase, which has been previously implicated in autophagy. In mammalian cells, we find that paxillin is redistributed from focal adhesions during nutrient deprivation, and paxillin-deficient cells exhibit defects in autophagosome formation. Together, these findings reveal a novel evolutionarily conserved role for paxillin in autophagy.

High-content profiling of cell responsiveness to graded substrates based on combinyatorially variant polymers.

PubMed

Liu, Er; Treiser, Matthew D; Patel, Hiral; Sung, Hak-Joon; Roskov, Kristen E; Kohn, Joachim; Becker, Matthew L; Moghe, Prabhas V

2009-08-01

We have developed a novel approach combining high information and high throughput analysis to characterize cell adhesive responses to biomaterial substrates possessing gradients in surface topography. These gradients were fabricated by subjecting thin film blends of tyrosine-derived polycarbonates, i.e. poly(DTE carbonate) and poly(DTO carbonate) to a gradient temperature annealing protocol. Saos-2 cells engineered with a green fluorescent protein (GFP) reporter for farnesylation (GFP-f) were cultured on the gradient substrates to assess the effects of nanoscale surface topology and roughness that arise during the phase separation process on cell attachment and adhesion strength. The high throughput imaging approach allowed us to rapidly identify the "global" and "high content" structure-property relationships between cell adhesion and biomaterial properties such as polymer chemistry and topography. This study found that cell attachment and spreading increased monotonically with DTE content and were significantly elevated at the position with intermediate regions corresponding to the highest "gradient" of surface roughness, while GFP-f farnesylation intensity descriptors were sensitively altered by surface roughness, even in cells with comparable levels of spreading.

Enforced hematopoietic cell E- and L-selectin ligand (HCELL) expression primes transendothelial migration of human mesenchymal stem cells.

PubMed

Thankamony, Sai P; Sackstein, Robert

2011-02-08

According to the multistep model of cell migration, chemokine receptor engagement (step 2) triggers conversion of rolling interactions (step 1) into firm adhesion (step 3), yielding transendothelial migration. We recently reported that glycosyltransferase-programmed stereosubstitution (GPS) of CD44 on human mesenchymal stem cells (hMSCs) creates the E-selectin ligand HCELL (hematopoietic cell E-selectin/L-selectin ligand) and, despite absence of CXCR4, systemically administered HCELL(+)hMSCs display robust osteotropism visualized by intravital microscopy. Here we performed studies to define the molecular effectors of this process. We observed that engagement of hMSC HCELL with E-selectin triggers VLA-4 adhesiveness, resulting in shear-resistant adhesion to ligand VCAM-1. This VLA-4 activation is mediated via a Rac1/Rap1 GTPase signaling pathway, resulting in transendothelial migration on stimulated human umbilical vein endothelial cells without chemokine input. These findings indicate that hMSCs coordinately integrate CD44 ligation and integrin activation, circumventing chemokine-mediated signaling, yielding a step 2-bypass pathway of the canonical multistep paradigm of cell migration.

β-Catenin–regulated myeloid cell adhesion and migration determine wound healing

PubMed Central

Amini-Nik, Saeid; Cambridge, Elizabeth; Yu, Winston; Guo, Anne; Whetstone, Heather; Nadesan, Puviindran; Poon, Raymond; Hinz, Boris; Alman, Benjamin A.

2014-01-01

A β-catenin/T cell factor–dependent transcriptional program is critical during cutaneous wound repair for the regulation of scar size; however, the relative contribution of β-catenin activity and function in specific cell types in the granulation tissue during the healing process is unknown. Here, cell lineage tracing revealed that cells in which β-catenin is transcriptionally active express a gene profile that is characteristic of the myeloid lineage. Mice harboring a macrophage-specific deletion of the gene encoding β-catenin exhibited insufficient skin wound healing due to macrophage-specific defects in migration, adhesion to fibroblasts, and ability to produce TGF-β1. In irradiated mice, only macrophages expressing β-catenin were able to rescue wound-healing deficiency. Evaluation of scar tissue collected from patients with hypertrophic and normal scars revealed a correlation between the number of macrophages within the wound, β-catenin levels, and cellularity. Our data indicate that β-catenin regulates myeloid cell motility and adhesion and that β-catenin–mediated macrophage motility contributes to the number of mesenchymal cells and ultimate scar size following cutaneous injury. PMID:24837430

A Flow Adhesion Assay to Study Leucocyte Recruitment to Human Hepatic Sinusoidal Endothelium Under Conditions of Shear Stress

PubMed Central

Shetty, Shishir; Weston, Christopher J.; Adams, David H.; Lalor, Patricia F.

2014-01-01

Leucocyte infiltration into human liver tissue is a common process in all adult inflammatory liver diseases. Chronic infiltration can drive the development of fibrosis and progression to cirrhosis. Understanding the molecular mechanisms that mediate leucocyte recruitment to the liver could identify important therapeutic targets for liver disease. The key interaction during leucocyte recruitment is that of inflammatory cells with endothelium under conditions of shear stress. Recruitment to the liver occurs within the low shear channels of the hepatic sinusoids which are lined by hepatic sinusoidal endothelial cells (HSEC). The conditions within the hepatic sinusoids can be recapitulated by perfusing leucocytes through channels lined by human HSEC monolayers at specific flow rates. In these conditions leucocytes undergo a brief tethering step followed by activation and firm adhesion, followed by a crawling step and subsequent transmigration across the endothelial layer. Using phase contrast microscopy, each step of this 'adhesion cascade' can be visualized and recorded followed by offline analysis. Endothelial cells or leucocytes can be pretreated with inhibitors to determine the role of specific molecules during this process. PMID:24686418

An Inducible Endothelial Cell Surface Glycoprotein Mediates Melanoma Adhesion

NASA Astrophysics Data System (ADS)

Rice, G. Edgar; Bevilacqua, Michael P.

1989-12-01

Hematogenous metastasis requires the arrest and extravasation of blood-borne tumor cells, possibly involving direct adhesive interactions with vascular endothelium. Cytokine activation of cultured human endothelium increases adhesion of melanoma and carcinoma cell lines. An inducible 110-kD endothelial cell surface glycoprotein, designated INCAM-110, appears to mediate adhesion of melanoma cells. In addition, an inducible endothelial receptor for neutrophils, ELAM-1, supports the adhesion of a human colon carcinoma cell line. Thus, activation of vascular endothelium in vivo that results in increased expression of INCAM-110 and ELAM-1 may promote tumor cell adhesion and affect the incidence and distribution of metastases.

Role of cellular adhesions in tissue dynamics spectroscopy

NASA Astrophysics Data System (ADS)

Merrill, Daniel A.; An, Ran; Turek, John; Nolte, David

2014-02-01

Cellular adhesions play a critical role in cell behavior, and modified expression of cellular adhesion compounds has been linked to various cancers. We tested the role of cellular adhesions in drug response by studying three cellular culture models: three-dimensional tumor spheroids with well-developed cellular adhesions and extracellular matrix (ECM), dense three-dimensional cell pellets with moderate numbers of adhesions, and dilute three-dimensional cell suspensions in agarose having few adhesions. Our technique for measuring the drug response for the spheroids and cell pellets was biodynamic imaging (BDI), and for the suspensions was quasi-elastic light scattering (QELS). We tested several cytoskeletal chemotherapeutic drugs (nocodazole, cytochalasin-D, paclitaxel, and colchicine) on three cancer cell lines chosen from human colorectal adenocarcinoma (HT-29), human pancreatic carcinoma (MIA PaCa-2), and rat osteosarcoma (UMR-106) to exhibit differences in adhesion strength. Comparing tumor spheroid behavior to that of cell suspensions showed shifts in the spectral motion of the cancer tissues that match predictions based on different degrees of cell-cell contacts. The HT-29 cell line, which has the strongest adhesions in the spheroid model, exhibits anomalous behavior in some cases. These results highlight the importance of using three-dimensional tissue models in drug screening with cellular adhesions being a contributory factor in phenotypic differences between the drug responses of tissue and cells.

Surface roughness mediated adhesion forces between borosilicate glass and gram-positive bacteria.

PubMed

Preedy, Emily; Perni, Stefano; Nipiĉ, Damijan; Bohinc, Klemen; Prokopovich, Polina

2014-08-12

It is well-known that a number of surface characteristics affect the extent of adhesion between two adjacent materials. One of such parameters is the surface roughness as surface asperities at the nanoscale level govern the overall adhesive forces. For example, the extent of bacterial adhesion is determined by the surface topography; also, once a bacteria colonizes a surface, proliferation of that species will take place and a biofilm may form, increasing the resistance of bacterial cells to removal. In this study, borosilicate glass was employed with varying surface roughness and coated with bovine serum albumin (BSA) in order to replicate the protein layer that covers orthopedic devices on implantation. As roughness is a scale-dependent process, relevant scan areas were analyzed using atomic force microscope (AFM) to determine Ra; furthermore, appropriate bacterial species were attached to the tip to measure the adhesion forces between cells and substrates. The bacterial species chosen (Staphylococci and Streptococci) are common pathogens associated with a number of implant related infections that are detrimental to the biomedical devices and patients. Correlation between adhesion forces and surface roughness (Ra) was generally better when the surface roughness was measured through scanned areas with size (2 × 2 μm) comparable to bacteria cells. Furthermore, the BSA coating altered the surface roughness without correlation with the initial values of such parameter; therefore, better correlations were found between adhesion forces and BSA-coated surfaces when actual surface roughness was used instead of the initial (nominal) values. It was also found that BSA induced a more hydrophilic and electron donor characteristic to the surfaces; in agreement with increasing adhesion forces of hydrophilic bacteria (as determined through microbial adhesion to solvents test) on BSA-coated substrates.

Multi-scale modelling of the dynamics of cell colonies: insights into cell-adhesion forces and cancer invasion from in silico simulations.

PubMed

Schlüter, Daniela K; Ramis-Conde, Ignacio; Chaplain, Mark A J

2015-02-06

Studying the biophysical interactions between cells is crucial to understanding how normal tissue develops, how it is structured and also when malfunctions occur. Traditional experiments try to infer events at the tissue level after observing the behaviour of and interactions between individual cells. This approach assumes that cells behave in the same biophysical manner in isolated experiments as they do within colonies and tissues. In this paper, we develop a multi-scale multi-compartment mathematical model that accounts for the principal biophysical interactions and adhesion pathways not only at a cell-cell level but also at the level of cell colonies (in contrast to the traditional approach). Our results suggest that adhesion/separation forces between cells may be lower in cell colonies than traditional isolated single-cell experiments infer. As a consequence, isolated single-cell experiments may be insufficient to deduce important biological processes such as single-cell invasion after detachment from a solid tumour. The simulations further show that kinetic rates and cell biophysical characteristics such as pressure-related cell-cycle arrest have a major influence on cell colony patterns and can allow for the development of protrusive cellular structures as seen in invasive cancer cell lines independent of expression levels of pro-invasion molecules.

The Epithelial Cell Adhesion Molecule EpCAM Is Required for Epithelial Morphogenesis and Integrity during Zebrafish Epiboly and Skin Development

PubMed Central

Slanchev, Krasimir; Carney, Thomas J.; Stemmler, Marc P.; Koschorz, Birgit; Amsterdam, Adam; Schwarz, Heinz; Hammerschmidt, Matthias

2009-01-01

The aberrant expression of the transmembrane protein EpCAM is associated with tumor progression, affecting different cellular processes such as cell–cell adhesion, migration, proliferation, differentiation, signaling, and invasion. However, the in vivo function of EpCAM still remains elusive due to the lack of genetic loss-of-function studies. Here, we describe epcam (tacstd) null mutants in zebrafish. Maternal-zygotic mutants display compromised basal protrusive activity and epithelial morphogenesis in cells of the enveloping layer (EVL) during epiboly. In partial redundancy with E-cadherin (Ecad), EpCAM made by EVL cells is further required for cell–cell adhesion within the EVL and, possibly, for proper attachment of underlying deep cells to the inner surface of the EVL, thereby also affecting deep cell epiboly movements. During later development, EpCAM per se becomes indispensable for epithelial integrity within the periderm of the skin, secondarily leading to disrupted morphology of the underlying basal epidermis and moderate hyper-proliferation of skin cells. On the molecular level, EVL cells of epcam mutant embryos display reduced levels of membranous Ecad, accompanied by an enrichment of tight junction proteins and a basal extension of apical junction complexes (AJCs). Our data suggest that EpCAM acts as a partner of E-cadherin to control adhesiveness and integrity as well as plasticity and morphogenesis within simple epithelia. In addition, EpCAM is required for the interaction of the epithelia with underlying cell layers. PMID:19609345

The cytoplasmic domain of the Drosophila cell adhesion molecule neuroglian is not essential for its homophilic adhesive properties in S2 cells.

PubMed

Hortsch, M; Wang, Y M; Marikar, Y; Bieber, A J

1995-08-11

Drosophila neuroglian is a transmembrane glycoprotein that has strong structural and sequence homology to the vertebrate L1 gene family of cell adhesion molecules (Bieber, A.J., Snow, P.M., Hortsch, M., Patel, N.H., Jacobs, J.R., Traquina, Z.R., Schilling, J., and Goodman, C.S. (1989) Cell 59, 447-460. Two different neuroglian protein forms that are generated by a differential splicing process are expressed in a tissue-specific fashion by embryonic and larval cells (Hortsch, M., Bieber, A.J., Patel, N.H., and Goodman, C.S. (1990) Neuron 4, 697-709). The two neuroglial polypeptides differ only in their cytoplasmic domains. Both of these neuroglian species, when transfected into the expressed in Drosophila S2 cells, induce the calcium-independent, homophilic aggregation of transformed cells. A third artificial neuroglian protein form was constructed by substituting the neuroglian transmembrane segment and cytoplasmic domains with the glycosyl phosphatidylinositol attachment signal of the Drosophila fasciclin I protein. This cDNA construct generates a glycosyl phosphatidylinositol-anchored form of neuroglian, which retains the ability to induce homophilic cell aggregation when expressed in S2 cells, and was able to interact with both of the two naturally occurring neuroglian polypeptides. These results demonstrate that neuroglian mediates a calcium-independent, homophilic cell adhesion activity and that neither cytoplasmic neuroglian domains nor a direct interaction with cytoskeletal elements is essential for this property.

The role of focal adhesion kinase in the regulation of cellular mechanical properties

NASA Astrophysics Data System (ADS)

Mierke, Claudia Tanja

2013-12-01

The regulation of mechanical properties is necessary for cell invasion into connective tissue or intra- and extravasation through the endothelium of blood or lymph vessels. Cell invasion is important for the regulation of many healthy processes such as immune response reactions and wound healing. In addition, cell invasion plays a role in disease-related processes such as tumor metastasis and autoimmune responses. Until now the role of focal adhesion kinase (FAK) in regulating mechanical properties of cells and its impact on cell invasion efficiency is still not well known. Thus, this review focuses on mechanical properties regulated by FAK in comparison to the mechano-regulating protein vinculin. Moreover, it points out the connection between cancer cell invasion and metastasis and FAK by showing that FAK regulates cellular mechanical properties required for cellular motility. Furthermore, it sheds light on the indirect interaction of FAK with vinculin by binding to paxillin, which then impairs the binding of paxillin to vinculin. In addition, this review emphasizes whether FAK fulfills regulatory functions similar to vinculin. In particular, it discusses the differences and the similarities between FAK and vinculin in regulating the biomechanical properties of cells. Finally, this paper highlights that both focal adhesion proteins, vinculin and FAK, synergize their functions to regulate the mechanical properties of cells such as stiffness and contractile forces. Subsequently, these mechanical properties determine cellular invasiveness into tissues and provide a source sink for future drug developments to inhibit excessive cell invasion and hence, metastases formation.

Quantitative adhesion characterization of antireflective coatings in multijunction photovoltaics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brock, Ryan; Rewari, Raunaq; Novoa, Fernando D.

We discuss the development of a new composite dual cantilever beam (cDCB) thin-film adhesion testing method, which enables the quantitative measurement of adhesion on the thin and fragile substrates used in multijunction photovoltaics. In particular, we address the adhesion of several 2- and 3-layer antireflective coating systems on multijunction cells. By varying interface chemistry and morphology through processing, we demonstrate the marked effects on adhesion and help to develop an understanding of how high adhesion can be achieved, as adhesion values ranging from 0.5 J/m2 to 10 J/m2 were measured. Damp heat (85 degrees C/85% RH) was used to invokemore » degradation of interfacial adhesion. We demonstrate that even with germanium substrates that fracture relatively easily, quantitative measurements of adhesion can be made at high test yield. The cDCB test is discussed as an important new methodology, which can be broadly applied to any system that makes use of thin, brittle, or otherwise fragile substrates.« less

The molecular basis of leukocyte adhesion involving phosphatidic acid and phospholipase D.

PubMed

Speranza, Francis; Mahankali, Madhu; Henkels, Karen M; Gomez-Cambronero, Julian

2014-10-17

Defining how leukocytes adhere to solid surfaces, such as capillary beds, and the subsequent migration through the extracellular matrix, is a central biological issue. We show here that phospholipase D (PLD) and its enzymatic reaction product, phosphatidic acid (PA), regulate cell adhesion of immune cells (macrophages and neutrophils) to collagen and have defined the underlying molecular mechanism in a spatio-temporal manner that coincides with PLD activity timing. A rapid (t½ = 4 min) and transient activation of the PLD1 isoform occurs upon adhesion, and a slower (t½ = 7.5 min) but prolonged (>30 min) activation occurs for PLD2. Importantly, PA directly binds to actin-related protein 3 (Arp3) at EC50 = 22 nm, whereas control phosphatidylcholine did not bind. PA-activated Arp3 hastens actin nucleation with a kinetics of t½ = 3 min at 300 nm (compared with controls of no PA, t½ = 5 min). Thus, PLD and PA are intrinsic components of cell adhesion, which reinforce each other in a positive feedback loop and react from cues from their respective solid substrates. In nascent adhesion, PLD1 is key, whereas a sustained adhesion in mature or established focal points is dependent upon PLD2, PA, and Arp3. A prolonged adhesion could effectively counteract the reversible intrinsic nature of this cellular process and constitute a key player in chronic inflammation. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Glatiramer acetate (GA) prevents TNF-α-induced monocyte adhesion to primary endothelial cells through interfering with the NF-κB pathway

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wei, Guoqian; Zhang, Xueyan; Su, Zhendong

2015-01-30

Highlights: • GA inhibited TNF-α-induced binding of monocytes to endothelial cells. • GA inhibited the induction of adhesion molecules MCP-1, VCAM-1 and E-selectin. • GA inhibits NF-κB p65 nuclear translocation and transcriptional activity. • GA inhibits TNF-α-induced IκBα degradation. - Abstract: Pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α) is considered to be the major one contributing to the process of development of endothelial dysfunction. Exposure to TNF-α induces the expression of a number of proinflammatory chemokines, such as monocyte chemotactic protein-1 (MCP-1), and adhesion molecules, including vascular adhesion molecule-1 (VCAM-1) and E-selectin, which mediate the interaction of invading monocytesmore » with vascular endothelial cells. Glatiramer acetate (GA) is a licensed clinical drug for treating patients suffering from multiple sclerosis (MS). The effects of GA in vascular disease have not shown before. In this study, we found that GA significantly inhibited TNF-α-induced binding of monocytes to endothelial cells. Mechanistically, we found that GA ameliorated the upregulation of MCP-1, VCAM-1, and E-selectin induced by TNF-α. Notably, this process is mediated by inhibiting the nuclear translocation and activation of NF-κB. Our results also indicate that GA pretreatment attenuates the up-regulation of COX-2 and iNOS. These data suggest that GA might have a potential benefit in therapeutic endothelial dysfunction related diseases.« less

Multi-scale modelling of the dynamics of cell colonies: insights into cell-adhesion forces and cancer invasion from in silico simulations

PubMed Central

Schlüter, Daniela K.; Ramis-Conde, Ignacio; Chaplain, Mark A. J.

2015-01-01

Studying the biophysical interactions between cells is crucial to understanding how normal tissue develops, how it is structured and also when malfunctions occur. Traditional experiments try to infer events at the tissue level after observing the behaviour of and interactions between individual cells. This approach assumes that cells behave in the same biophysical manner in isolated experiments as they do within colonies and tissues. In this paper, we develop a multi-scale multi-compartment mathematical model that accounts for the principal biophysical interactions and adhesion pathways not only at a cell–cell level but also at the level of cell colonies (in contrast to the traditional approach). Our results suggest that adhesion/separation forces between cells may be lower in cell colonies than traditional isolated single-cell experiments infer. As a consequence, isolated single-cell experiments may be insufficient to deduce important biological processes such as single-cell invasion after detachment from a solid tumour. The simulations further show that kinetic rates and cell biophysical characteristics such as pressure-related cell-cycle arrest have a major influence on cell colony patterns and can allow for the development of protrusive cellular structures as seen in invasive cancer cell lines independent of expression levels of pro-invasion molecules. PMID:25519994

[Expression of cell adhesion molecules in acute leukemia cell].

PubMed

Ju, Xiaoping; Peng, Min; Xu, Xiaoping; Lu, Shuqing; Li, Yao; Ying, Kang; Xie, Yi; Mao, Yumin; Xia, Fang

2002-11-01

To investigate the role of cell adhesion molecule in the development and extramedullary infiltration (EI) of acute leukemia. The expressions of neural cell adhesion molecule (NCAM) gene, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule (VCAM-1) genes in 25 acute leukemia patients bone marrow cells were detected by microarray and reverse transcriptase-polymerase chain reaction (RT-PCR). The expressions of NCAM, ICAM-1 and VCAM-1 gene were significantly higher in acute leukemia cells and leukemia cells with EI than in normal tissues and leukemia cells without EI, respectively, both by cDNA microarray and by RT-PCR. The cDNA microarray is a powerful technique in analysis of acute leukemia cells associated genes. High expressions of cell adhesion molecule genes might be correlated with leukemia pathogenesis and infiltration of acute leukemia cell.

Tobacco smoke induces epithelial barrier dysfunction via receptor EphA2 signaling.

PubMed

Nasreen, Najmunnisa; Khodayari, Nazli; Sriram, Peruvemba S; Patel, Jawaharlal; Mohammed, Kamal A

2014-06-15

Erythropoietin-producing human hepatocellular carcinoma (Eph) receptors are the largest family of receptor tyrosine kinases (RTKs) that mediate various cellular and developmental processes. The degrees of expression of these key molecules control the cell-cell interactions. Although the role of Eph receptors and their ligand Ephrins is well studied in developmental processes, their function in tobacco smoke (TS)-induced epithelial barrier dysfunction is unknown. We hypothesized that TS may induce permeability in bronchial airway epithelial cell (BAEpC) monolayer by modulating receptor EphA2 expression, actin cytoskeleton, adherens junction, and focal adhesion proteins. Here we report that in BAEpCs, acute TS exposure significantly upregulated EphA2 and EphrinA1 expression, disrupted the actin filaments, decreased E-cadherin expression, and increased protein permeability, whereas the focal adhesion protein paxillin was unaffected. Silencing the receptor EphA2 expression with silencing interference RNA (siRNA) significantly attenuated TS-induced hyperpermeability in BAEpCs. In addition, when BAEpC monolayer was transfected with EphA2-expressing plasmid and treated with recombinant EphrinA1, the transepithelial electrical resistance decreased significantly. Furthermore, TS downregulated E-cadherin expression and induced hyperpermeability across BAEpC monolayer in a Erk1/Erk2, p38, and JNK MAPK-dependent manner. TS induced hyperpermeability in BAEpC monolayer by targeting cell-cell adhesions, and interestingly cell-matrix adhesions were unaffected. The present data suggest that TS causes significant damage to the BAEpCs via induction of EphA2 and downregulation of E-cadherin. Induction of EphA2 in the BAEpCs exposed to TS may be an important signaling event in the pathogenesis of TS-induced epithelial injury.

The cancer cell adhesion resistome: mechanisms, targeting and translational approaches.

PubMed

Dickreuter, Ellen; Cordes, Nils

2017-06-27

Cell adhesion-mediated resistance limits the success of cancer therapies and is a great obstacle to overcome in the clinic. Since the 1990s, where it became clear that adhesion of tumor cells to the extracellular matrix is an important mediator of therapy resistance, a lot of work has been conducted to understand the fundamental underlying mechanisms and two paradigms were deduced: cell adhesion-mediated radioresistance (CAM-RR) and cell adhesion-mediated drug resistance (CAM-DR). Preclinical work has evidently demonstrated that targeting of integrins, adapter proteins and associated kinases comprising the cell adhesion resistome is a promising strategy to sensitize cancer cells to both radiotherapy and chemotherapy. Moreover, the cell adhesion resistome fundamentally contributes to adaptation mechanisms induced by radiochemotherapy as well as molecular drugs to secure a balanced homeostasis of cancer cells for survival and growth. Intriguingly, this phenomenon provides a basis for synthetic lethal targeted therapies simultaneously administered to standard radiochemotherapy. In this review, we summarize current knowledge about the cell adhesion resistome and highlight targeting strategies to override CAM-RR and CAM-DR.

Acellular derivatives of mesenchymal stem cells prevent peritoneal adhesions in an animal model.

PubMed

Rojo, Daniel; Conget, Paulette

2018-03-01

Peritoneal adhesions are nonanatomical connections that bind organs to the abdominal wall or among them. They arise after peritoneal injury, which triggers an inflammatory response followed by a healing process that leads to fibrotic tissue formation. Mesenchymal stem cells and their secretion products, also referred to as acellular derivatives (ACDs), have anti-inflammatory, fibrinolytic, and antifibrogenic properties. The aim of this study was to determine the effect of intraoperative administration of ACD on the appearance, severity, and progression of peritoneal adhesions, in an animal model. Cecal erosions were mechanically induced in adult mice. Before closure, the vehicle, ACD, or Seprafilm was administered. Seven days later, the presence and grade of peritoneal adhesions were assessed macroscopically. One, 3, and 7 d after intervention, molecular and cellular markers of inflammation, fibrinolysis, and fibrogenesis were evaluated both locally and systemically. ACDs avoided the appearance of clinically relevant peritoneal adhesions. The vehicle had no effect, and Seprafilm reduced them inconsistently. The antiadhesive effect of ACD was associated with an early reduction of proinflammatory cytokine (tumor necrosis factor-alpha and interferon-gamma) secretion and leukocyte (polymorphonuclears, mononuclears, and macrophages) infiltration. High levels of D-dimer, low fibrin deposits, low myofibroblasts infiltration, and less fibrosis were also observed. ACD administered at the end of abdominal surgeries prevents the formation of peritoneal adhesions due to the modulation of inflammatory, fibrinolytic, and fibrogenic processes. Copyright © 2017 Elsevier Inc. All rights reserved.

Single-cell force spectroscopy as a technique to quantify human red blood cell adhesion to subendothelial laminin.

PubMed

Maciaszek, Jamie L; Partola, Kostyantyn; Zhang, Jing; Andemariam, Biree; Lykotrafitis, George

2014-12-18

Single-cell force spectroscopy (SCFS), an atomic force microscopy (AFM)-based assay, enables quantitative study of cell adhesion while maintaining the native state of surface receptors in physiological conditions. Human healthy and pathological red blood cells (RBCs) express a large number of surface proteins which mediate cell-cell interactions, or cell adhesion to the extracellular matrix. In particular, RBCs adhere with high affinity to subendothelial matrix laminin via the basal cell adhesion molecule and Lutheran protein (BCAM/Lu). Here, we established SCFS as an in vitro technique to study human RBC adhesion at baseline and following biochemical treatment. Using blood obtained from healthy human subjects, we recorded adhesion forces from single RBCs attached to AFM cantilevers as the cell was pulled-off of substrates coated with laminin protein. We found that an increase in the overall cell adhesion measured via SCFS is correlated with an increase in the resultant total force measured on 1 µm(2) areas of the RBC membrane. Further, we showed that SCFS can detect significant changes in the adhesive response of RBCs to modulation of the cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA) pathway. Lastly, we identified variability in the RBC adhesion force to laminin amongst the human subjects, suggesting that RBCs maintain diverse levels of active BCAM/Lu adhesion receptors. By using single-cell measurements, we established a powerful new method for the quantitative measurement of single RBC adhesion with specific receptor-mediated binding. Copyright © 2014 Elsevier Ltd. All rights reserved.

Dextran and gelatin based photocrosslinkable tissue adhesive.

PubMed

Wang, Tao; Nie, Jun; Yang, Dongzhi

2012-11-06

A two-component tissue adhesive based on biocompatible and bio-degradable polymers (oxidized urethane dextran (Dex-U-AD) and gelatin) was prepared and photocrosslinked under the ultraviolet (UV) irradiation. The adhesive could adhere to surface of gelatin, which simulated the human tissue steadily. The structures of above Dex-U-AD were characterized by FTIR, (1)H NMR spectroscopy and XRD. The adhesion property of result products was evaluated by lap-shear test. The maximum adhesion strength could reach to 4.16±0.72 MPa which was significantly higher than that of fibrin glue. The photopolymerization process of Dex-U-AD/gelatin was monitored by real time infrared spectroscopy (RTIR). It took less than 5 min to complete the curing process. The cytotoxicity of Dex-U-AD/gelatin also was evaluated which indicated that Dex-U-AD/gelatin gels were nontoxic to L929 cell. The relationship between all the above-mentioned properties and degree of oxidization of Dex-U-AD was assessed. The obtained products have the potential to serve as tissue adhesive in the future. Copyright © 2012 Elsevier Ltd. All rights reserved.

Surface Expression of Precursor N-cadherin Promotes Tumor Cell Invasion12

PubMed Central

Maret, Deborah; Gruzglin, Eugenia; Sadr, Mohamad Seyed; Siu, Vincent; Shan, Weisong; Koch, Alexander W; Seidah, Nabil G; Del Maestro, Rolando F; Colman, David R

2010-01-01

The expression of N-cadherin (NCAD) has been shown to correlate with increased tumor cell motility and metastasis. However, NCAD-mediated adhesion is a robust phenomenon and therefore seems to be inconsistent with the “release” from intercellular adhesion required for invasion. We show that in the most invasive melanoma and brain tumor cells, altered posttranslational processing results in abundant nonadhesive precursor N-cadherin (proNCAD) at the cell surface, although total NCAD levels remain constant. We demonstrate that aberrantly processed proNCAD promotes cell migration and invasion in vitro. Furthermore, in human tumor specimens, we find high levels of proNCAD as well, supporting an overall conclusion that proNCAD and mature NCAD coexist on these tumor cell surfaces and that it is the ratio between these functionally antagonistic moieties that directly correlates with invasion potential. Our work provides insight into what may be a widespread mechanism for invasion and metastasis and challenges the current dogma of the functional roles played by classic cadherins in tumor progression. PMID:21170270

Regulation of epithelial and lymphocyte cell adhesion by adenosine deaminase-CD26 interaction.

PubMed Central

Ginés, Silvia; Mariño, Marta; Mallol, Josefa; Canela, Enric I; Morimoto, Chikao; Callebaut, Christian; Hovanessian, Ara; Casadó, Vicent; Lluis, Carmen; Franco, Rafael

2002-01-01

The extra-enzymic function of cell-surface adenosine deaminase (ADA), an enzyme mainly localized in the cytosol but also found on the cell surface of monocytes, B cells and T cells, has lately been the subject of numerous studies. Cell-surface ADA is able to transduce co-stimulatory signals in T cells via its interaction with CD26, an integral membrane protein that acts as ADA-binding protein. The aim of the present study was to explore whether ADA-CD26 interaction plays a role in the adhesion of lymphocyte cells to human epithelial cells. To meet this aim, different lymphocyte cell lines (Jurkat and CEM T) expressing endogenous, or overexpressing human, CD26 protein were tested in adhesion assays to monolayers of colon adenocarcinoma human epithelial cells, Caco-2, which express high levels of cell-surface ADA. Interestingly, the adhesion of Jurkat and CEM T cells to a monolayer of Caco-2 cells was greatly dependent on CD26. An increase by 50% in the cell-to-cell adhesion was found in cells containing higher levels of CD26. Incubation with an anti-CD26 antibody raised against the ADA-binding site or with exogenous ADA resulted in a significant reduction (50-70%) of T-cell adhesion to monolayers of epithelial cells. The role of ADA-CD26 interaction in the lymphocyte-epithelial cell adhesion appears to be mediated by CD26 molecules that are not interacting with endogenous ADA (ADA-free CD26), since SKW6.4 (B cells) that express more cell-surface ADA showed lower adhesion than T cells. Adhesion stimulated by CD26 and ADA is mediated by T cell lymphocyte function-associated antigen. A role for ADA-CD26 interaction in cell-to-cell adhesion was confirmed further in integrin activation assays. FACS analysis revealed a higher expression of activated integrins on T cell lines in the presence of increasing amounts of exogenous ADA. Taken together, these results suggest that the ADA-CD26 interaction on the cell surface has a role in lymphocyte-epithelial cell adhesion. PMID:11772392

Plasticity, elasticity, and adhesion energy of plant cell walls: nanometrology of lignin loss using atomic force microscopy

DOE PAGES

Farahi, R. H.; Charrier, Anne M.; Tolbert, Allison K.; ...

2017-03-10

The complex organic polymer, lignin, abundant in plants, prevents the efficient extraction of sugars from the cell walls that is required for large scale biofuel production. Because lignin removal is crucial in overcoming this challenge, the question of how the nanoscale properties of the plant cell ultrastructure correlate with delignification processes is important. Here, we report how distinct molecular domains can be identified and how physical quantities of adhesion energy, elasticity, and plasticity undergo changes, and whether such quantitative observations can be used to characterize delignification. By chemically processing biomass, and employing nanometrology, the various stages of lignin removal aremore » shown to be distinguished through the observed morphochemical and nanomechanical variations. Such spatially resolved correlations between chemistry and nanomechanics during deconstruction not only provide a better understanding of the cell wall architecture but also is vital for devising optimum chemical treatments.« less

Isolation and in vitro binding of mating type plus fertilization tubules from Chlamydomonas.

PubMed

Wilson, Nedra F

2008-01-01

During fertilization in Chlamydomonas, adhesion and fusion of gametes occur at the tip of specialized regions of the plasma membrane, known as mating structures. The mating type minus (mt[-]) structure is a slightly raised dome-shaped region located at the apical end of the cell body. In contrast, the activated mating type plus (mt[+]) structure is an actin-filled, microvillouslike organelle. Interestingly, a similar type of "fusion organelle" is conserved across diverse groups. Chlamydomonas provides an ideal model system for studying the process of gametic cell fusion in that it is amenable to genetic manipulations as well as cell and molecular biological approaches. Moreover, the ease of culturing Chlamydomonas combined with the ability to isolate the mt(+) fertilization tubule and the development of in vitro assays for adhesion makes it an ideal system for biochemical studies focused on dissecting the molecular mechanisms that underlie the complex process of gametic cell fusion.

Protopine inhibits heterotypic cell adhesion in MDA-MB-231 cells through down-regulation of multi-adhesive factors.

PubMed

He, Kai; Gao, Jian-Li

2014-01-01

A Chinese herb Corydalis yanhusuo W.T. Wang that showed anticancer and anti-angiogenesis effects in our previous studies was presented for further studies. In the present study, we studied the anticancer proliferation and adhesion effects of five alkaloids which were isolated from Corydalis yanhusuo. MTT dose response curves, cell migration assay, cell invasion assay, as well as three types of cell adhesive assay were performed on MDA-MB-231 human breast cancer cells. The mechanism of the compounds on inhibiting heterotypic cell adhesion were further explored by determining the expression of epidermal growth factor receptor (EGFR), Intercellular adhesion molecule 1 (ICAM-1), αv-integrin, β1-integrin and β5-integrin by western blotting assay. In five tested alkaloids, only protopine exhibited anti-adhesive and anti-invasion effects in MDA-MB-231 cells, which contributed to the anti-metastasis effect of Corydalis yanhusuo. The results showed that after treatment with protopine for 90 min, the expression of EGFR, ICAM-1, αv-integrin, β1-integrin and β5-integrin were remarkably reduced. The present results suggest that protopine seems to inhibit the heterotypic cell adhesion between MDA-MB-231 cells, and human umbilical vein endothelial cells by changing the expression of adhesive factors.

Hybrid cell adhesive material for instant dielectrophoretic cell trapping and long-term cell function assessment.

PubMed

Reyes, Darwin R; Hong, Jennifer S; Elliott, John T; Gaitan, Michael

2011-08-16

Dielectrophoresis (DEP) for cell manipulation has focused, for the most part, on approaches for separation/enrichment of cells of interest. Advancements in cell positioning and immobilization onto substrates for cell culture, either as single cells or as cell aggregates, has benefited from the intensified research efforts in DEP (electrokinetic) manipulation. However, there has yet to be a DEP approach that provides the conditions for cell manipulation while promoting cell function processes such as cell differentiation. Here we present the first demonstration of a system that combines DEP with a hybrid cell adhesive material (hCAM) to allow for cell entrapment and cell function, as demonstrated by cell differentiation into neuronlike cells (NLCs). The hCAM, comprised of polyelectrolytes and fibronectin, was engineered to function as an instantaneous cell adhesive surface after DEP manipulation and to support long-term cell function (cell proliferation, induction, and differentiation). Pluripotent P19 mouse embryonal carcinoma cells flowing within a microchannel were attracted to the DEP electrode surface and remained adhered onto the hCAM coating under a fluid flow field after the DEP forces were removed. Cells remained viable after DEP manipulation for up to 8 d, during which time the P19 cells were induced to differentiate into NLCs. This approach could have further applications in areas such as cell-cell communication, three-dimensional cell aggregates to create cell microenvironments, and cell cocultures.

Effects of Physicochemical Factors on the Adhesion to Cellulose Avicel of the Ruminal Bacteria Ruminococcus flavefaciens and Fibrobacter succinogenes subsp. succinogenes.

PubMed

Roger, V; Fonty, G; Komisarczuk-Bony, S; Gouet, P

1990-10-01

Ruminococcus flavefaciens adhered instantly to cellulose, while Fibrobacter succinogenes had the highest percentage of adherent cells after about 25 min of contact between bacteria and cellulose. Adhesion of R. flavefaciens was unaffected by high concentrations of sugars (5%), temperature, pH, oxygen, metabolic inhibitors, and lack of Na. In contrast, the attachment was affected by the removal of divalent cations (Mg and Ca), the presence of cellulose derivatives (methylcellulose and hydroxyethylcellulose), and cystine. Adhesion of F. succinogenes was sensitive to low and high temperatures, high concentrations of glucose and cellobiose (5%), hydroxyethylcellulose (0.1%), redox potential, pH, lack of monovalent cations, and the presence of an inhibitor of membrane ATPases or lasalocid and monensin. Cells of F. succinogenes heated at 100 degrees C no longer were adherent. On the other hand, adhesion was insensitive to the lack of divalent cations (Mg and Ca), the presence of 2,4-dinitrophenol, tetrachlorosalicylanilide, or inhibitors of the electron transfer chains. Adhesion of F. succinogenes seems to be related to the metabolic functions of the cell. External proteins and/or cellulases themselves might play a part in the attachment process. Several mechanisms are probably involved in the adhesion of R. flavefaciens, the main one being the interaction between the large glycocalyx and the divalent cations Ca and Mg. Hydrophobic bonds and enzymes may also be involved.

Low-expression of E-cadherin in leukaemia cells causes loss of homophilic adhesion and promotes cell growth.

PubMed

Rao, Qing; Wang, Ji-Ying; Meng, Jihong; Tang, Kejing; Wang, Yanzhong; Wang, Min; Xing, Haiyan; Tian, Zheng; Wang, Jianxiang

2011-09-01

E-cadherin (epithelial cadherin) belongs to the calcium-dependent adhesion molecule superfamily and is implicated in the interactions of haematopoietic progenitors and bone marrow stromal cells. Adhesion capacity to bone marrow stroma was impaired for leukaemia cells, suggesting that a breakdown of adhesive mechanisms governed by an adhesion molecule may exist in leukaemic microenvironment. We previously found that E-cadherin was low expressed in primary acute leukaemia cells compared with normal bone marrow mononuclear cells. In this study, we investigate the functional importance of low E-cadherin expression in leukaemia cell behaviours and investigate its effects in the abnormal interaction of leukaemic cells with stromal cells. After expression of E-cadherin was restored by a demethylating agent in leukaemia cells, E-cadherin-specific adhesion was enhanced. Additionally, siRNA (small interfering RNA)-mediated silencing of E-cadherin in Raji cells resulted in a reduction of cell homophilic adhesion and enhancement of cell proliferation and colony formation. These results suggest that low expression of E-cadherin contributes to the vigorous growth and transforming ability of leukaemic cells.

Grip and slip of L1-CAM on adhesive substrates direct growth cone haptotaxis

PubMed Central

Abe, Kouki; Katsuno, Hiroko; Toriyama, Michinori; Baba, Kentarou; Mori, Tomoyuki; Hakoshima, Toshio; Kanemura, Yonehiro; Watanabe, Rikiya; Inagaki, Naoyuki

2018-01-01

Chemical cues presented on the adhesive substrate direct cell migration, a process termed haptotaxis. To migrate, cells must generate traction forces upon the substrate. However, how cells probe substrate-bound cues and generate directional forces for migration remains unclear. Here, we show that the cell adhesion molecule (CAM) L1-CAM is involved in laminin-induced haptotaxis of axonal growth cones. L1-CAM underwent grip and slip on the substrate. The ratio of the grip state was higher on laminin than on the control substrate polylysine; this was accompanied by an increase in the traction force upon laminin. Our data suggest that the directional force for laminin-induced growth cone haptotaxis is generated by the grip and slip of L1-CAM on the substrates, which occur asymmetrically under the growth cone. This mechanism is distinct from the conventional cell signaling models for directional cell migration. We further show that this mechanism is disrupted in a human patient with L1-CAM syndrome, suffering corpus callosum agenesis and corticospinal tract hypoplasia. PMID:29483251

Suppression of complement regulatory protein C1 inhibitor in vascular endothelial activation by inhibiting vascular cell adhesion molecule-1 action

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Haimou; Qin, Gangjian; Liang, Gang

Increased expression of adhesion molecules by activated endothelium is a critical feature of vascular inflammation associated with the several diseases such as endotoxin shock and sepsis/septic shock. Our data demonstrated complement regulatory protein C1 inhibitor (C1INH) prevents endothelial cell injury. We hypothesized that C1INH has the ability of an anti-endothelial activation associated with suppression of expression of adhesion molecule(s). C1INH blocked leukocyte adhesion to endothelial cell monolayer in both static assay and flow conditions. In inflammatory condition, C1INH reduced vascular cell adhesion molecule (VCAM-1) expression associated with its cytoplasmic mRNA destabilization and nuclear transcription level. Studies exploring the underlying mechanismmore » of C1INH-mediated suppression in VCAM-1 expression were related to reduction of NF-{kappa}B activation and nuclear translocation in an I{kappa}B{alpha}-dependent manner. The inhibitory effects were associated with reduction of inhibitor I{kappa}B kinase activity and stabilization of the NF-{kappa}B inhibitor I{kappa}B. These findings indicate a novel role for C1INH in inhibition of vascular endothelial activation. These observations could provide the basis for new therapeutic application of C1INH to target inflammatory processes in different pathologic situations.« less

Mechanical Coordination of Single-Cell and Collective-Cell Amoeboid Migration

NASA Astrophysics Data System (ADS)

Del Alamo, Juan Carlos

Amoeboid migration consists of the sequential repetition of pseudopod extensions and retractions driven by actin polymerization and actomyosin contraction, and requires cells to apply mechanical forces on their surroundings. We measure the three-dimensional forces exerted by chemotaxing Dictyostelium cells, and examine wild-type cells as well as mutants with defects in contractility, F-actin polymerization, internal F-actin crosslinking, and cortical integrity. We find that cells pull on their substrate adhesions using two distinct, yet interconnected mechanisms: axial actomyosin contractility and cortical tension. The 3D pulling forces generated by both mechanisms are internally balanced by an increase in cytoplasmic pressure that allows cells to push on their substrate, and we show that these pushing forces are relevant for cell invasion and migration in three-dimensional environments. We observe that cells migrate mainly by forming two stationary adhesion sites at the front and back of the cell, over which the cell body moves forward in a step-wise fashion. During this process, the traction forces at each adhesion site are switched off and subsequently their direction is reversed. The cell migration speed is found to be proportional to the rate at which cells are able regulate these forces to produce the cell shape changes needed for locomotion, which is increased when axial contractility overcomes the stabilizing effect of cortical tension. This spatiotemporal coordination is conserved in streams of multiple migratory cells connected head to tail, which also migrate by exerting traction forces on stationary sites. Furthermore, we observe that trailing cells reuse the adhesion sites of the leading cells. Finally, we provide evidence that the above modes of migration may be conserved in a range of other amoeboid-type moving cells such as neutrophils.

Leading-process actomyosin coordinates organelle positioning and adhesion receptor dynamics in radially migrating cerebellar granule neurons

DOE PAGES

Trivedi, Niraj; Ramahi, Joseph S.; Karakaya, Mahmut; ...

2014-12-02

During brain development, neurons migrate from germinal zones to their final positions to assemble neural circuits. A unique saltatory cadence involving cyclical organelle movement (e.g., centrosome motility) and leading-process actomyosin enrichment prior to nucleokinesis organizes neuronal migration. While functional evidence suggests that leading-process actomyosin is essential for centrosome motility, the role of the actin-enriched leading process in globally organizing organelle transport or traction forces remains unexplored. Our results show that myosin ii motors and F-actin dynamics are required for Golgi apparatus positioning before nucleokinesis in cerebellar granule neurons (CGNs) migrating along glial fibers. Moreover, we show that primary cilia aremore » motile organelles, localized to the leading-process F-actin-rich domain and immobilized by pharmacological inhibition of myosin ii and F-actin dynamics. Finally, leading process adhesion dynamics are dependent on myosin ii and F-actin. In conclusion, we propose that actomyosin coordinates the overall polarity of migrating CGNs by controlling asymmetric organelle positioning and cell-cell contacts as these cells move along their glial guides.« less

Leading-process actomyosin coordinates organelle positioning and adhesion receptor dynamics in radially migrating cerebellar granule neurons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trivedi, Niraj; Ramahi, Joseph S.; Karakaya, Mahmut

During brain development, neurons migrate from germinal zones to their final positions to assemble neural circuits. A unique saltatory cadence involving cyclical organelle movement (e.g., centrosome motility) and leading-process actomyosin enrichment prior to nucleokinesis organizes neuronal migration. While functional evidence suggests that leading-process actomyosin is essential for centrosome motility, the role of the actin-enriched leading process in globally organizing organelle transport or traction forces remains unexplored. Our results show that myosin ii motors and F-actin dynamics are required for Golgi apparatus positioning before nucleokinesis in cerebellar granule neurons (CGNs) migrating along glial fibers. Moreover, we show that primary cilia aremore » motile organelles, localized to the leading-process F-actin-rich domain and immobilized by pharmacological inhibition of myosin ii and F-actin dynamics. Finally, leading process adhesion dynamics are dependent on myosin ii and F-actin. In conclusion, we propose that actomyosin coordinates the overall polarity of migrating CGNs by controlling asymmetric organelle positioning and cell-cell contacts as these cells move along their glial guides.« less

Endothelial NOS is required for SDF-1alpha/CXCR4-mediated peripheral endothelial adhesion of c-kit+ bone marrow stem cells.

PubMed

Kaminski, Alexander; Ma, Nan; Donndorf, Peter; Lindenblatt, Nicole; Feldmeier, Gregor; Ong, Lee-Lee; Furlani, Dario; Skrabal, Christian A; Liebold, Andreas; Vollmar, Brigitte; Steinhoff, Gustav

2008-01-01

In the era of intravascular approaches for regenerative cell therapy, the underlying mechanisms of stem cell migration to non-marrow tissue have not been clarified. We hypothesized that next to a local inflammatory response implying adhesion molecule expression, endothelial nitric oxide synthase (eNOS)-dependent signaling is required for stromal- cell-derived factor-1 alpha (SDF-1alpha)-induced adhesion of c-kit+ cells to the vascular endothelium. SDF-1alpha/tumor necrosis factor-alpha (TNF-alpha)-induced c-kit+-cell shape change and migration capacity was studied in vitro using immunohistochemistry and Boyden chamber assays. In vivo interaction of c-kit+ cells from bone marrow with the endothelium in response to SDF-1alpha/TNF-alpha stimulation was visualized in the cremaster muscle microcirculation of wild-type (WT) and eNOS (-/-) mice using intravital fluorescence microscopy. In addition, NOS activity was inhibited with N-nitro-L-arginine-methylester-hydrochloride in WT mice. To reveal c-kit+-specific adhesion behavior, endogenous leukocytes (EL) and c-kit+ cells from peripheral blood served as control. Moreover, intercellular adhesion molecule-1 (ICAM-1) and CXCR4 were blocked systemically to determine their role in inflammation-related c-kit+-cell adhesion. In vitro, SDF-1alpha enhanced c-kit+-cell migration. In vivo, SDF-1alpha alone triggered endothelial rolling-not firm adherence-of c-kit+ cells in WT mice. While TNF-alpha alone had little effect on adhesion of c-kit+ cells, it induced maximum endothelial EL adherence. However, after combined treatment with SDF-1alpha+TNF-alpha, endothelial adhesion of c-kit+ cells increased independent of their origin, while EL adhesion was not further incremented. Systemic treatment with anti-ICAM-1 and anti-CXCR4-monoclonal antibody completely abolished endothelial c-kit+-cell adhesion. In N-nitro-L-arginine-methylester-hydrochloride-treated WT mice as well as in eNOS (-/-) mice, firm endothelial adhesion of c-kit+ cells was entirely abrogated, while EL adhesion was significantly increased. The chemokine SDF-1alpha mediates firm adhesion c-kit+ cells only in the presence of TNF-alpha stimulation via an ICAM-1- and CXCR4-dependent mechanism. The presence of eNOS appears to be a crucial and specific factor for firm c-kit+-cell adhesion to the vascular endothelium.

The Molecular Architecture of Cell Adhesion: Dynamic Remodeling Revealed by Videonanoscopy.

PubMed

Sergé, Arnauld

2016-01-01

The plasma membrane delimits the cell, which is the basic unit of living organisms, and is also a privileged site for cell communication with the environment. Cell adhesion can occur through cell-cell and cell-matrix contacts. Adhesion proteins such as integrins and cadherins also constitute receptors for inside-out and outside-in signaling within proteolipidic platforms. Adhesion molecule targeting and stabilization relies on specific features such as preferential segregation by the sub-membrane cytoskeleton meshwork and within membrane proteolipidic microdomains. This review presents an overview of the recent insights brought by the latest developments in microscopy, to unravel the molecular remodeling occurring at cell contacts. The dynamic aspect of cell adhesion was recently highlighted by super-resolution videomicroscopy, also named videonanoscopy. By circumventing the diffraction limit of light, nanoscopy has allowed the monitoring of molecular localization and behavior at the single-molecule level, on fixed and living cells. Accessing molecular-resolution details such as quantitatively monitoring components entering and leaving cell contacts by lateral diffusion and reversible association has revealed an unexpected plasticity. Adhesion structures can be highly specialized, such as focal adhesion in motile cells, as well as immune and neuronal synapses. Spatiotemporal reorganization of adhesion molecules, receptors, and adaptors directly relates to structure/function modulation. Assembly of these supramolecular complexes is continuously balanced by dynamic events, remodeling adhesions on various timescales, notably by molecular conformation switches, lateral diffusion within the membrane and endo/exocytosis. Pathological alterations in cell adhesion are involved in cancer evolution, through cancer stem cell interaction with stromal niches, growth, extravasation, and metastasis.

Differential Expression and Enzymatic Activity of DPPIV/CD26 Affects Migration Ability of Cervical Carcinoma Cells

PubMed Central

Beckenkamp, Aline; Willig, Júlia Biz; Santana, Danielle Bertodo; Nascimento, Jéssica; Paccez, Juliano Domiraci; Zerbini, Luiz Fernando; Bruno, Alessandra Nejar; Pilger, Diogo André; Wink, Márcia Rosângela; Buffon, Andréia

2015-01-01

Dipeptidyl peptidase IV (DPPIV/CD26) is a transmembrane glycoprotein that inactivates or degrades some bioactive peptides and chemokines. For this reason, it regulates cell proliferation, migration and adhesion, showing its role in cancer processes. This enzyme is found mainly anchored onto the cell membrane, although it also has a soluble form, an enzymatically active isoform. In the present study, we investigated DPPIV/CD26 activity and expression in cervical cancer cell lines (SiHa, HeLa and C33A) and non-tumorigenic HaCaT cells. The effect of the DPPIV/CD26 inhibitor (sitagliptin phosphate) on cell migration and adhesion was also evaluated. Cervical cancer cells and keratinocytes exhibited DPPIV/CD26 enzymatic activity both membrane-bound and in soluble form. DPPIV/CD26 expression was observed in HaCaT, SiHa and C33A, while in HeLa cells it was almost undetectable. We observed higher migratory capacity of HeLa, when compared to SiHa. But in the presence of sitagliptin SiHa showed an increase in migration, indicating that, at least in part, cell migration is regulated by DPPIV/CD26 activity. Furthermore, in the presence of sitagliptin phosphate, SiHa and HeLa cells exhibited a significant reduction in adhesion. However this mechanism seems to be mediated independent of DPPIV/CD26. This study demonstrates, for the first time, the activity and expression of DPPIV/CD26 in cervical cancer cells and the effect of sitagliptin phosphate on cell migration and adhesion. PMID:26222679

Differential Expression and Enzymatic Activity of DPPIV/CD26 Affects Migration Ability of Cervical Carcinoma Cells.

PubMed

Beckenkamp, Aline; Willig, Júlia Biz; Santana, Danielle Bertodo; Nascimento, Jéssica; Paccez, Juliano Domiraci; Zerbini, Luiz Fernando; Bruno, Alessandra Nejar; Pilger, Diogo André; Wink, Márcia Rosângela; Buffon, Andréia

2015-01-01

Dipeptidyl peptidase IV (DPPIV/CD26) is a transmembrane glycoprotein that inactivates or degrades some bioactive peptides and chemokines. For this reason, it regulates cell proliferation, migration and adhesion, showing its role in cancer processes. This enzyme is found mainly anchored onto the cell membrane, although it also has a soluble form, an enzymatically active isoform. In the present study, we investigated DPPIV/CD26 activity and expression in cervical cancer cell lines (SiHa, HeLa and C33A) and non-tumorigenic HaCaT cells. The effect of the DPPIV/CD26 inhibitor (sitagliptin phosphate) on cell migration and adhesion was also evaluated. Cervical cancer cells and keratinocytes exhibited DPPIV/CD26 enzymatic activity both membrane-bound and in soluble form. DPPIV/CD26 expression was observed in HaCaT, SiHa and C33A, while in HeLa cells it was almost undetectable. We observed higher migratory capacity of HeLa, when compared to SiHa. But in the presence of sitagliptin SiHa showed an increase in migration, indicating that, at least in part, cell migration is regulated by DPPIV/CD26 activity. Furthermore, in the presence of sitagliptin phosphate, SiHa and HeLa cells exhibited a significant reduction in adhesion. However this mechanism seems to be mediated independent of DPPIV/CD26. This study demonstrates, for the first time, the activity and expression of DPPIV/CD26 in cervical cancer cells and the effect of sitagliptin phosphate on cell migration and adhesion.

Mechanotransduction: all signals point to cytoskeleton, matrix, and integrins

NASA Technical Reports Server (NTRS)

Alenghat, Francis J.; Ingber, Donald E.

2002-01-01

Mechanical stresses modulate cell function by either activating or tuning signal transduction pathways. Mechanotransduction, the process by which cells convert mechanical stimuli into a chemical response, occurs both in cells specialized for sensing mechanical cues and in parenchymal cells whose primary function is not mechanosensory. However, common among the various responses to mechanical stress is the importance of direct or indirect connections between the internal cytoskeleton, the extracellular matrix (ECM), and traditional signal transducing molecules. In many instances, these elements converge at focal adhesions, sites of structural attachment between the cytoskeleton and ECM that are anchored by cell surface integrin receptors. Alenghat and Ingber discuss the accumulating evidence for the central role of cytoskeleton, ECM, and integrin-anchored focal adhesions in several mechanotransduction pathways.

Effects of active and inactive phospholipase D2 on signal transduction, adhesion, migration, invasion, and metastasis in EL4 lymphoma cells.

PubMed

Knoepp, Stewart M; Chahal, Manpreet S; Xie, Yuhuan; Zhang, Zhihong; Brauner, Daniel J; Hallman, Mark A; Robinson, Stephanie A; Han, Shujie; Imai, Masaki; Tomlinson, Stephen; Meier, Kathryn E

2008-09-01

The phosphatidylcholine-using phospholipase D (PLD) isoform PLD2 is widely expressed in mammalian cells and is activated in response to a variety of promitogenic agonists. In this study, active and inactive hemagglutinin-tagged human PLD2 (HA-PLD2) constructs were stably expressed in an EL4 cell line lacking detectable endogenous PLD1 or PLD2. The overall goal of the study was to examine the roles of PLD2 in cellular signal transduction and cell phenotype. HA-PLD2 confers PLD activity that is activated by phorbol ester, ionomycin, and okadaic acid. Proliferation and Erk activation are unchanged in cells transfected with active PLD2; proliferation rate is decreased in cells expressing inactive PLD2. Basal tyrosine phosphorylation of focal adhesion kinase (FAK) is increased in cells expressing active PLD2, as is phosphorylation of Akt; inactive PLD2 has no effect. Expression of active PLD2 is associated with increased spreading and elongation of cells on tissue culture plastic, whereas inactive PLD2 inhibits cell spreading. Inactive PLD2 also inhibits cell adhesion, migration, and serum-induced invasion. Cells expressing active PLD2 form metastases in syngeneic mice, as do the parental cells; cells expressing inactive PLD2 form fewer metastases than parental cells. In summary, active PLD2 enhances FAK phosphorylation, Akt activation, and cell invasion in EL4 lymphoma cells, whereas inactive PLD2 exerts inhibitory effects on adhesion, migration, invasion, and tumor formation. Overall, expression of active PLD2 enhances processes favorable to lymphoma cell metastasis, whereas expression of inactive PLD2 inhibits metastasis.

High Fat Diet Induces Adhesion of Platelets to Endothelium in Two Models of Dyslipidemia

PubMed Central

Gonzalez, Jaime; Donoso, Wendy; Díaz, Natalia; Albornoz, María Eliana; Huilcaman, Ricardo; Morales, Erik

2014-01-01

Cardiovascular diseases (CVD) represent about 30% of all global deaths. It is currently accepted that, in the atherogenic process, platelets play an important role, contributing to endothelial activation and modulation of the inflammatory phenomenon, promoting the beginning and formation of lesions and their subsequent thrombotic complications. The objective of the present work was to study using immunohistochemistry, the presence of platelets, monocytes/macrophages, and cell adhesion molecules (CD61, CD163, and CD54), in two stages of the atheromatous process. CF-1 mice fed a fat diet were used to obtain early stages of atheromatous process, denominated early stage of atherosclerosis, and ApoE−/− mice fed a fat diet were used to observe advanced stages of atherosclerosis. The CF-1 mice model presented immunostaining on endothelial surface for all three markers studied; the advanced atherosclerosis model in ApoE−/− mice also presented granular immunostaining on lesion thickness, for the same markers. These results suggest that platelets participate in atheromatous process from early stages to advance d stages. High fat diet induces adhesion of platelets to endothelial cells in vivo. These findings support studying the participation of platelets in the formation of atheromatous plate. PMID:25328689

High fat diet induces adhesion of platelets to endothelium in two models of dyslipidemia.

PubMed

Gonzalez, Jaime; Donoso, Wendy; Díaz, Natalia; Albornoz, María Eliana; Huilcaman, Ricardo; Morales, Erik; Moore-Carrasco, Rodrigo

2014-01-01

Cardiovascular diseases (CVD) represent about 30% of all global deaths. It is currently accepted that, in the atherogenic process, platelets play an important role, contributing to endothelial activation and modulation of the inflammatory phenomenon, promoting the beginning and formation of lesions and their subsequent thrombotic complications. The objective of the present work was to study using immunohistochemistry, the presence of platelets, monocytes/macrophages, and cell adhesion molecules (CD61, CD163, and CD54), in two stages of the atheromatous process. CF-1 mice fed a fat diet were used to obtain early stages of atheromatous process, denominated early stage of atherosclerosis, and ApoE(-/-) mice fed a fat diet were used to observe advanced stages of atherosclerosis. The CF-1 mice model presented immunostaining on endothelial surface for all three markers studied; the advanced atherosclerosis model in ApoE(-/-) mice also presented granular immunostaining on lesion thickness, for the same markers. These results suggest that platelets participate in atheromatous process from early stages to advance d stages. High fat diet induces adhesion of platelets to endothelial cells in vivo. These findings support studying the participation of platelets in the formation of atheromatous plate.

Membrane adhesion dictates Golgi stacking and cisternal morphology.

PubMed

Lee, Intaek; Tiwari, Neeraj; Dunlop, Myun Hwa; Graham, Morven; Liu, Xinran; Rothman, James E

2014-02-04

Two classes of proteins that bind to each other and to Golgi membranes have been implicated in the adhesion of Golgi cisternae to each other to form their characteristic stacks: Golgi reassembly and stacking proteins 55 and 65 (GRASP55 and GRASP65) and Golgin of 45 kDa and Golgi matrix protein of 130 kDa. We report here that efficient stacking occurs in the absence of GRASP65/55 when either Golgin is overexpressed, as judged by quantitative electron microscopy. The Golgi stacks in these GRASP-deficient HeLa cells were normal both in morphology and in anterograde cargo transport. This suggests the simple hypothesis that the total amount of adhesive energy gluing cisternae dictates Golgi cisternal stacking, irrespective of which molecules mediate the adhesive process. In support of this hypothesis, we show that adding artificial adhesive energy between cisternae and mitochondria by dimerizing rapamycin-binding domain and FK506-binding protein domains that are attached to cisternal adhesive proteins allows mitochondria to invade the stack and even replace Golgi cisternae within a few hours. These results indicate that although Golgi stacking is a highly complicated process involving a large number of adhesive and regulatory proteins, the overriding principle of a Golgi stack assembly is likely to be quite simple. From this simplified perspective, we propose a model, based on cisternal adhesion and cisternal maturation as the two core principles, illustrating how the most ancient form of Golgi stacking might have occurred using only weak cisternal adhesive processes because of the differential between the rate of influx and outflux of membrane transport through the Golgi.

Membrane adhesion dictates Golgi stacking and cisternal morphology

PubMed Central

Lee, Intaek; Tiwari, Neeraj; Dunlop, Myun Hwa; Graham, Morven; Liu, Xinran; Rothman, James E.

2014-01-01

Two classes of proteins that bind to each other and to Golgi membranes have been implicated in the adhesion of Golgi cisternae to each other to form their characteristic stacks: Golgi reassembly and stacking proteins 55 and 65 (GRASP55 and GRASP65) and Golgin of 45 kDa and Golgi matrix protein of 130 kDa. We report here that efficient stacking occurs in the absence of GRASP65/55 when either Golgin is overexpressed, as judged by quantitative electron microscopy. The Golgi stacks in these GRASP-deficient HeLa cells were normal both in morphology and in anterograde cargo transport. This suggests the simple hypothesis that the total amount of adhesive energy gluing cisternae dictates Golgi cisternal stacking, irrespective of which molecules mediate the adhesive process. In support of this hypothesis, we show that adding artificial adhesive energy between cisternae and mitochondria by dimerizing rapamycin-binding domain and FK506-binding protein domains that are attached to cisternal adhesive proteins allows mitochondria to invade the stack and even replace Golgi cisternae within a few hours. These results indicate that although Golgi stacking is a highly complicated process involving a large number of adhesive and regulatory proteins, the overriding principle of a Golgi stack assembly is likely to be quite simple. From this simplified perspective, we propose a model, based on cisternal adhesion and cisternal maturation as the two core principles, illustrating how the most ancient form of Golgi stacking might have occurred using only weak cisternal adhesive processes because of the differential between the rate of influx and outflux of membrane transport through the Golgi. PMID:24449908

Receptor-mediated membrane adhesion of lipid-polymer hybrid (LPH) nanoparticles studied by dissipative particle dynamics simulations

NASA Astrophysics Data System (ADS)

Li, Zhenlong; Gorfe, Alemayehu A.

2014-12-01

Lipid-polymer hybrid (LPH) nanoparticles represent a novel class of targeted drug delivery platforms that combine the advantages of liposomes and biodegradable polymeric nanoparticles. However, the molecular details of the interaction between LPHs and their target cell membranes remain poorly understood. We have investigated the receptor-mediated membrane adhesion process of a ligand-tethered LPH nanoparticle using extensive dissipative particle dynamics (DPD) simulations. We found that the spontaneous adhesion process follows a first-order kinetics characterized by two distinct stages: a rapid nanoparticle-membrane engagement, followed by a slow growth in the number of ligand-receptor pairs coupled with structural re-organization of both the nanoparticle and the membrane. The number of ligand-receptor pairs increases with the dynamic segregation of ligands and receptors toward the adhesion zone causing an out-of-plane deformation of the membrane. Moreover, the fluidity of the lipid shell allows for strong nanoparticle-membrane interactions to occur even when the ligand density is low. The LPH-membrane avidity is enhanced by the increased stability of each receptor-ligand pair due to the geometric confinement and the cooperative effect arising from multiple binding events. Thus, our results reveal the unique advantages of LPH nanoparticles as active cell-targeting nanocarriers and provide some general principles governing nanoparticle-cell interactions that may aid future design of LPHs with improved affinity and specificity for a given target of interest.

The mechanical response of talin

NASA Astrophysics Data System (ADS)

Yao, Mingxi; Goult, Benjamin T.; Klapholz, Benjamin; Hu, Xian; Toseland, Christopher P.; Guo, Yingjian; Cong, Peiwen; Sheetz, Michael P.; Yan, Jie

2016-07-01

Talin, a force-bearing cytoplasmic adapter essential for integrin-mediated cell adhesion, links the actin cytoskeleton to integrin-based cell-extracellular matrix adhesions at the plasma membrane. Its C-terminal rod domain, which contains 13 helical bundles, plays important roles in mechanosensing during cell adhesion and spreading. However, how the structural stability and transition kinetics of the 13 helical bundles of talin are utilized in the diverse talin-dependent mechanosensing processes remains poorly understood. Here we report the force-dependent unfolding and refolding kinetics of all talin rod domains. Using experimentally determined kinetics parameters, we determined the dynamics of force fluctuation during stretching of talin under physiologically relevant pulling speeds and experimentally measured extension fluctuation trajectories. Our results reveal that force-dependent stochastic unfolding and refolding of talin rod domains make talin a very effective force buffer that sets a physiological force range of only a few pNs in the talin-mediated force transmission pathway.

Regulation of RAW 264.7 macrophages behavior on anodic TiO2 nanotubular arrays

NASA Astrophysics Data System (ADS)

Yao, Shenglian; Feng, Xujia; Li, Wenhao; Wang, Lu-Ning; Wang, Xiumei

2017-12-01

Titanium (Ti) implants with TiO2 nanotubular arrays on the surface could regulate cells adhesion, proliferation and differentiation to determine the bone integration. Additionally, the regulation of immune cells could improve osteogenesis or lead in appropriate immune reaction. Thus, we evaluate the behavior of RAW264.7 macrophages on TiO2 nanotubular arrays with a wide range diameter (from 20 to 120 nm) fabricated by an electrochemical anodization process. In this work, the proliferation, cell viability and cytokine/chemokine secretion were evaluated by CCK-8, live/dead staining and ELISA, respectively. SEM and confocal microscopy were used to observe the adhesion morphology. Results showed that the small size nanotube surface was benefit for the macrophages adhesion and proliferation, while larger size surface could reduce the inflammatory response. These findings contribute to the design of immune-regulating Ti implants surface that supports successful implantation.

Relating cell and tissue mechanics: implications and applications.

PubMed

Jakab, Karoly; Damon, Brook; Marga, Françoise; Doaga, Octavian; Mironov, Vladimir; Kosztin, Ioan; Markwald, Roger; Forgacs, Gabor

2008-09-01

The Differential Adhesion Hypothesis (DAH) posits that differences in adhesion provide the driving force for morphogenetic processes. A manifestation of differential adhesion is tissue liquidity and a measure for it is tissue surface tension. In terms of this property, DAH correctly predicts global developmental tissue patterns. However, it provides little information on how these patterns arise from the movement and shape changes of cells. We provide strong qualitative and quantitative support for tissue liquidity both in true developmental context and in vitro assays. We follow the movement and characteristic shape changes of individual cells in the course of specific tissue rearrangements leading to liquid-like configurations. Finally, we relate the measurable tissue-liquid properties to molecular entities, whose direct determination under realistic three-dimensional culture conditions is not possible. Our findings confirm the usefulness of tissue liquidity and provide the scientific underpinning for a novel tissue engineering technology.

Cell Adhesion-dependent Serine 85 Phosphorylation of Paxillin Modulates Focal Adhesion Formation and Haptotactic Migration via Association with the C-terminal Tail Domain of Talin*

PubMed Central

Kwak, Tae Kyoung; Lee, Mi-Sook; Ryu, Jihye; Choi, Yoon-Ju; Kang, Minkyung; Jeong, Doyoung; Lee, Jung Weon

2012-01-01

Integrin-mediated adhesion to extracellular matrix proteins is dynamically regulated during morphological changes and cell migration. Upon cell adhesion, protein-protein interactions among molecules at focal adhesions (FAs) play major roles in the regulation of cell morphogenesis and migration. Although tyrosine phosphorylation of paxillin is critically involved in adhesion-mediated signaling, the significance of paxillin phosphorylation at Ser-85 and the mechanism by which it regulates cell migration remain unclear. In this study, we examined how Ser-85 phosphorylation of paxillin affects FA formation and cell migration. We found that paxillin phosphorylation at Ser-85 occurred during HeLa cell adhesion to collagen I and was concomitant with tyrosine phosphorylation of both focal adhesion kinase and talin. However, the non-phosphorylatable S85A mutant of paxillin impaired cell spreading, FA turnover, and migration toward collagen I but not toward serum. Furthermore, whereas the (presumably indirect) interaction between paxillin and the C-terminal tail of talin led to dynamic FAs at the cell boundary, S85A paxillin did not bind talin and caused stabilized FAs in the central region of cells. Together, these observations suggest that cell adhesion-dependent Ser-85 phosphorylation of paxillin is important for its interaction with talin and regulation of dynamic FAs and cell migration. PMID:22761432

Soft tissue cell adhesion to titanium abutments after different cleaning procedures: Preliminary results of a randomized clinical trial

PubMed Central

Canullo, Luigi; Peñarrocha-Oltra, David; Marchionni, Silvia; Bagán, Leticia; Micarelli, Costanza

2014-01-01

Objectives: A randomized controlled trial was performed to assess soft tissue cell adhesion to implant titanium abutments subjected to different cleaning procedures and test if plasma cleaning can enhance cell adhesion at an early healing time. Study Design: Eighteen patients with osseointegrated and submerged implants were included. Before re-opening, 18 abutments were divided in 3 groups corresponding to different clinical conditions with different cleaning processes: no treatment (G1), laboratory customization and cleaning by steam (G2), cleaning by plasma of Argon (G3). Abutments were removed after 1 week and scanning electron microscopy was used to analyze cell adhesion to the abutment surface quantitatively (percentage of area occupied by cells) and qualitatively (aspect of adhered cells and presence of contaminants). Results: Mean percentages of area occupied by cells were 17.6 ± 22.7%, 16.5 ± 12.9% and 46.3 ± 27.9% for G1, G2 and G3 respectively. Differences were statistically significant between G1 and G3 (p=0.030), close to significance between G2 and G3 (p=0.056), and non-significant between G1 and G2 (p=0.530). The proportion of samples presenting adhered cells was homogeneous among the 3 groups (p-valor = 1.000). In all cases cells presented a flattened aspect; in 2 cases cells were less efficiently adhered and in 1 case cells presented filipodia. Three cases showed contamination with cocobacteria. Conclusions: Within the limits of the present study, plasma of Argon may enhance cell adhesion to titanium abutments, even at the early stage of soft tissue healing. Further studies with greater samples are necessary to confirm these findings. Key words:Connective tissue, dental abutments, randomized controlled trial, clinical research, glow discharged abutment, plasma cleaning. PMID:24121917

A mucus adhesion promoting protein, MapA, mediates the adhesion of Lactobacillus reuteri to Caco-2 human intestinal epithelial cells.

PubMed

Miyoshi, Yukihiro; Okada, Sanae; Uchimura, Tai; Satoh, Eiichi

2006-07-01

Lactobacillus reuteri is one of the dominant lactobacilli found in the gastrointestinal tract of various animals. A surface protein of L. reuteri 104R, mucus adhesion promoting protein (MapA), is considered to be an adhesion factor of this strain. We investigated the relation between MapA and adhesion of L. reuteri to human intestinal (Caco-2) cells. Quantitative analysis of the adhesion of L. reuteri strains to Caco-2 cells showed that various L. reuteri strains bind not only to mucus but also to intestinal epithelial cells. In addition, purified MapA bound to Caco-2 cells, and this binding inhibited the adhesion of L. reuteri in a concentration-dependent manner. Based on these observations, the adhesion of L. reuteri appears due to the binding of MapA to receptor-like molecules on Caco-2 cells. Further, far-western analysis indicated the existence of multiple receptor-like molecules in Caco-2 cells.

Quantum dots as bio-labels for the localization of a small plant adhesion protein

NASA Astrophysics Data System (ADS)

Ravindran, Sathyajith; Kim, Sunran; Martin, Rebecca; Lord, Elizabeth M.; Ozkan, Cengiz S.

2005-01-01

Recently, semiconducting nanoparticles have been successfully applied in live mammalian cell cultures, as alternative biological labels for multicolour imaging, by verifying known physiological processes. Here, we report the application of semiconducting nanoparticles to live plant cells in culture. Utilizing this technique, we have uncovered new knowledge regarding the localization of a plant pollen tube adhesion protein, stigma/stylar cysteine-rich adhesin (SCA). The potential of these nanoparticles is evident when the results were compared with conventional immunolocalization methods using fluorescently labelled antibodies.

Synergistic effect of two cell recognition systems: glycosphingolipid-glycosphingolipid interaction and integrin receptor interaction with pericellular matrix protein.

PubMed

Kojima, N; Hakomori, S

1991-12-01

GM3-expressing cells adhere, spread and migrate on plastic plates coated with Gg3, LacCer and Gb4, but not with other glycosphingolipids (GSLs). Thus, cell adhesion, spreading and migration through GSL-GSL interaction occur in an analogous fashion to the interaction of cells with adhesive matrix proteins [AP, e.g. fibronectin (FN), laminin (LN)] through their integrin receptors. In this study, the adhesion of two GM3-expressing cell lines (B16 melanoma and HEL299 fibroblast) on plastic plates co-coated with GSL plus AP is compared with adhesion on plates coated with GSL (Gg3 or LacCer) alone, or coated with AP alone. Results show that: (i) cell adhesion on GSL-coated plates takes place earlier in the incubation period than that on AP-coated plates; (ii) cell adhesion, as well as spreading, was greatly enhanced (in terms of strength and rapidity) on plates co-coated with GSL plus AP; (iii) repulsion (negative adhesion) of cells was observed on plates co-coated with AP plus N-acetyl-GM3 (NAcGM3) and was presumably based on repulsive NAcGM3-NAcGM3 interaction; (iv) GM3-dependent cell adhesion on GSL-coated plates, as well as synergistic promotion of cell adhesion (based on the GSL-GSL and AP-integrin systems), was suppressed by incubation of cells with anti-GM3 monoclonal antibody DH2 or sialidase. Synergistic adhesion of cells on GSL/AP co-coated plates was less inhibited by incubation with peptide sequences RGDS or YIGSR than was adhesion on plates coated with AP alone.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo studies of sickle red blood cells.

PubMed

Kaul, Dhananjay K; Fabry, Mary E

2004-03-01

The defining clinical feature of sickle cell anemia is periodic occurrence of painful vasoocclusive crisis. Factors that promote trapping and sickling of red cells in the microcirculation are likely to trigger vasoocclusion. The marked red cell heterogeneity in sickle blood and abnormal adhesion of sickle red cells to vascular endothelium would be major disruptive influences. Using ex vivo and in vivo models, the authors show how to dissect the relative contribution of heterogeneous sickle red cell classes to adhesive and obstructive events. These studies revealed that (1) both rheological abnormalities and adhesion of sickle red cells contribute to their abnormal hemodynamic behavior, (2) venules are the sites of sickle cell adhesion, and (3) sickle red cell deformability plays an important role in adhesive and obstructive events. Preferential adhesion of deformable sickle red cells in postcapillary venules followed by selective trapping of dense sickle red cells could result in vasoocclusion. An updated version of this 2-step model is presented. The multifactorial nature of sickle red cell adhesion needs to be considered in designing antiadhesive therapy in vivo.

Exosomes from iPSCs Delivering siRNA Attenuate Intracellular Adhesion Molecule-1 Expression and Neutrophils Adhesion in Pulmonary Microvascular Endothelial Cells.

PubMed

Ju, Zhihai; Ma, Jinhui; Wang, Chen; Yu, Jie; Qiao, Yeru; Hei, Feilong

2017-04-01

The pro-inflammatory activation of pulmonary microvascular endothelial cells resulting in continuous expression of cellular adhesion molecules, and subsequently recruiting primed neutrophils to form a firm neutrophils-endothelium (PMN-EC) adhesion, has been examined and found to play a vital role in acute lung injury (ALI). RNA interference (RNAi) is a cellular process through harnessing a natural pathway silencing target gene based on recognition and subsequent degradation of specific mRNA sequences. It opens a promising approach for precision medicine. However, this application was hampered by many obstacles, such as immunogenicity, instability, toxicity problems, and difficulty in across the biological membrane. In this study, we reprogrammed urine exfoliated renal epithelial cells into human induced pluripotent stem cells (huiPSCs) and purified the exosomes (Exo) from huiPSCs as RNAi delivery system. Through choosing the episomal system to deliver transcription factors, we obtained a non-integrating huiPSCs. Experiments in both vitro and vivo demonstrated that these huiPSCs possess the pluripotent properties. The exosomes of huiPSCs isolated by differential centrifugation were visualized by transmission electron microscopy (TEM) showing a typical exosomal appearance with an average diameter of 122 nm. Immunoblotting confirmed the presence of the typical exosomal markers, including CD63, TSG 101, and Alix. Co-cultured PKH26-labeled exosomes with human primary pulmonary microvascular endothelial cells (HMVECs) confirmed that they could be internalized by recipient cells at a time-dependent manner. Then, electroporation was used to introduce siRNA against intercellular adhesion molecule-1 (ICAM-1) into exosomes to form an Exo/siRNA compound. The Exo/siRNA compound efficiently delivered the target siRNA into HMVECs causing selective gene silencing, inhibiting the ICAM-1 protein expression, and PMN-EC adhesion induced by lipopolysaccharide (LPS). These data suggest that huiPSCs exosomes could be used as a natural gene delivery vector to transport therapeutic siRNAs for alleviating inflammatory responses in recipient cells.

Impaired Integrin-mediated Adhesion and Signaling in Fibroblasts Expressing a Dominant-negative Mutant PTP1B

PubMed Central

Arregui, Carlos O.; Balsamo, Janne; Lilien, Jack

1998-01-01

To investigate the role of nonreceptor protein tyrosine phosphatase 1B (PTP1B) in β1-integrin– mediated adhesion and signaling, we transfected mouse L cells with normal and catalytically inactive forms of the phosphatase. Parental cells and cells expressing the wild-type or mutant PTP1B were assayed for (a) adhesion, (b) spreading, (c) presence of focal adhesions and stress fibers, and (d) tyrosine phosphorylation. Parental cells and cells expressing wild-type PTP1B show similar morphology, are able to attach and spread on fibronectin, and form focal adhesions and stress fibers. In contrast, cells expressing the inactive PTP1B have a spindle-shaped morphology, reduced adhesion and spreading on fibronectin, and almost a complete absence of focal adhesions and stress fibers. Attachment to fibronectin induces tyrosine phosphorylation of focal adhesion kinase (FAK) and paxillin in parental cells and cells transfected with the wild-type PTP1B, while in cells transfected with the mutant PTP1B, such induction is not observed. Additionally, in cells expressing the mutant PTP1B, tyrosine phosphorylation of Src is enhanced and activity is reduced. Lysophosphatidic acid temporarily reverses the effects of the mutant PTP1B, suggesting the existence of a signaling pathway triggering focal adhesion assembly that bypasses the need for active PTP1B. PTP1B coimmunoprecipitates with β1-integrin from nonionic detergent extracts and colocalizes with vinculin and the ends of actin stress fibers in focal adhesions. Our data suggest that PTP1B is a critical regulatory component of integrin signaling pathways, which is essential for adhesion, spreading, and formation of focal adhesions. PMID:9813103

Flagellin based biomimetic coatings: From cell-repellent surfaces to highly adhesive coatings.

PubMed

Kovacs, Boglarka; Patko, Daniel; Szekacs, Inna; Orgovan, Norbert; Kurunczi, Sandor; Sulyok, Attila; Khanh, Nguyen Quoc; Toth, Balazs; Vonderviszt, Ferenc; Horvath, Robert

2016-09-15

Biomimetic coatings with cell-adhesion-regulating functionalities are intensively researched today. For example, cell-based biosensing for drug development, biomedical implants, and tissue engineering require that the surface adhesion of living cells is well controlled. Recently, we have shown that the bacterial flagellar protein, flagellin, adsorbs through its terminal segments to hydrophobic surfaces, forming an oriented monolayer and exposing its variable D3 domain to the solution. Here, we hypothesized that this nanostructured layer is highly cell-repellent since it mimics the surface of the flagellar filaments. Moreover, we proposed flagellin as a carrier molecule to display the cell-adhesive RGD (Arg-Gly-Asp) peptide sequence and induce cell adhesion on the coated surface. The D3 domain of flagellin was replaced with one or more RGD motifs linked by various oligopeptides modulating flexibility and accessibility of the inserted segment. The obtained flagellin variants were applied to create surface coatings inducing cell adhesion and spreading to different levels, while wild-type flagellin was shown to form a surface layer with strong anti-adhesive properties. As reference surfaces synthetic polymers were applied which have anti-adhesive (PLL-g-PEG poly(l-lysine)-graft-poly(ethylene glycol)) or adhesion inducing properties (RGD-functionalized PLL-g-PEG). Quantitative adhesion data was obtained by employing optical biochips and microscopy. Cell-adhesion-regulating coatings can be simply formed on hydrophobic surfaces by using the developed flagellin-based constructs. The developed novel RGD-displaying flagellin variants can be easily obtained by bacterial production and can serve as alternatives to create cell-adhesion-regulating biomimetic coatings. In the present work, we show for the first time that. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Regulation of T-lymphocyte motility, adhesion and de-adhesion by a cell surface mechanism directed by low density lipoprotein receptor-related protein 1 and endogenous thrombospondin-1.

PubMed

Talme, Toomas; Bergdahl, Eva; Sundqvist, Karl-Gösta

2014-06-01

T lymphocytes are highly motile and constantly reposition themselves between a free-floating vascular state, transient adhesion and migration in tissues. The regulation behind this unique dynamic behaviour remains unclear. Here we show that T cells have a cell surface mechanism for integrated regulation of motility and adhesion and that integrin ligands and CXCL12/SDF-1 influence motility and adhesion through this mechanism. Targeting cell surface-expressed low-density lipoprotein receptor-related protein 1 (LRP1) with an antibody, or blocking transport of LRP1 to the cell surface, perturbed the cell surface distribution of endogenous thrombospondin-1 (TSP-1) while inhibiting motility and potentiating cytoplasmic spreading on intercellular adhesion molecule 1 (ICAM-1) and fibronectin. Integrin ligands and CXCL12 stimulated motility and enhanced cell surface expression of LRP1, intact TSP-1 and a 130,000 MW TSP-1 fragment while preventing formation of a de-adhesion-coupled 110 000 MW TSP-1 fragment. The appearance of the 130 000 MW TSP-1 fragment was inhibited by the antibody that targeted LRP1 expression, inhibited motility and enhanced spreading. The TSP-1 binding site in the LRP1-associated protein, calreticulin, stimulated adhesion to ICAM-1 through intact TSP-1 and CD47. Shear flow enhanced cell surface expression of intact TSP-1. Hence, chemokines and integrin ligands up-regulate a dominant motogenic pathway through LRP1 and TSP-1 cleavage and activate an associated adhesion pathway through the LRP1-calreticulin complex, intact TSP-1 and CD47. This regulation of T-cell motility and adhesion makes pro-adhesive stimuli favour motile responses, which may explain why T cells prioritize movement before permanent adhesion.

Regulation of tumor cell migration by protein tyrosine phosphatase (PTP)-proline-, glutamate-, serine-, and threonine-rich sequence (PEST)

PubMed Central

Zheng, Yanhua; Lu, Zhimin

2013-01-01

Protein tyrosine phosphatase (PTP)–proline-, glutamate-, serine-, and threonine-rich sequence (PEST) is ubiquitously expressed and is a critical regulator of cell adhesion and migration. PTP-PEST activity can be regulated transcriptionally via gene deletion or mutation in several types of human cancers or via post-translational modifications, including phosphorylation, oxidation, and caspase-dependent cleavage. PTP-PEST interacts with and dephosphorylates cytoskeletal and focal adhesion-associated proteins. Dephosphorylation of PTP-PEST substrates regulates their enzymatic activities and/or their interaction with other proteins and plays an essential role in the tumor cell migration process. PMID:23237212

Pea Border Cell Maturation and Release Involve Complex Cell Wall Structural Dynamics1[OPEN

PubMed Central

2017-01-01

The adhesion of plant cells is vital for support and protection of the plant body and is maintained by a variety of molecular associations between cell wall components. In some specialized cases, though, plant cells are programmed to detach, and root cap-derived border cells are examples of this. Border cells (in some species known as border-like cells) provide an expendable barrier between roots and the environment. Their maturation and release is an important but poorly characterized cell separation event. To gain a deeper insight into the complex cellular dynamics underlying this process, we undertook a systematic, detailed analysis of pea (Pisum sativum) root tip cell walls. Our study included immunocarbohydrate microarray profiling, monosaccharide composition determination, Fourier-transformed infrared microspectroscopy, quantitative reverse transcription-PCR of cell wall biosynthetic genes, analysis of hydrolytic activities, transmission electron microscopy, and immunolocalization of cell wall components. Using this integrated glycobiology approach, we identified multiple novel modes of cell wall structural and compositional rearrangement during root cap growth and the release of border cells. Our findings provide a new level of detail about border cell maturation and enable us to develop a model of the separation process. We propose that loss of adhesion by the dissolution of homogalacturonan in the middle lamellae is augmented by an active biophysical process of cell curvature driven by the polarized distribution of xyloglucan and extensin epitopes. PMID:28400496

Osteoblast adhesion, migration, and proliferation variations on chemically patterned nanocrystalline diamond films evaluated by live-cell imaging.

PubMed

Broz, Antonin; Ukraintsev, Egor; Kromka, Alexander; Rezek, Bohuslav; Hubalek Kalbacova, Marie

2017-05-01

Cell fate modulation by adapting the surface of a biocompatible material is nowadays a challenge in implantology, tissue engineering as well as in construction of biosensors. Nanocrystalline diamond (NCD) thin films are considered promising in these fields due to their extraordinary physical and chemical properties and diverse ways in which they can be modified structurally and chemically. The initial cell distribution, the rate of cell adhesion, distance of cell migration and also the cell proliferation are influenced by the NCD surface termination. Here, we use real-time live-cell imaging to investigate the above-mentioned processes on oxidized NCD (NCD-O) and hydrogenated NCD (NCD-H) to elucidate cell preference to the NCD-O especially on surfaces with microscopic surface termination patterns. Cells adhere more slowly and migrate farther on NCD-H than on NCD-O. Cells seeded with a fetal bovine serum (FBS) supplement in the medium move across the surface prior to adhesion. In the absence of FBS, the cells adhere immediately, but still exhibit different migration and proliferation on NCD-O/H regions. We discuss the impact of these effects on the formation of cell arrays on micropatterned NCD. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1469-1478, 2017. © 2017 Wiley Periodicals, Inc.

Inhibiting focal adhesion kinase (FAK) blocks IL-4 induced VCAM-1 expression and eosinophil recruitment in vitro and in vivo.

PubMed

Aulakh, Gurpreet K; Petri, Björn; Wojcik, Katarzyna M; Colarusso, Pina; Lee, James J; Patel, Kamala D

2018-04-06

Leukocyte recruitment plays a critical role during both normal inflammation and chronic inflammatory diseases, and ongoing studies endeavor to better understand the complexities of this process. Focal adhesion kinase (FAK) is well known for its role in cancer, yet it also has been shown to regulate aspects of neutrophil and B16 melanoma cell recruitment by rapidly influencing endothelial cell focal adhesion dynamics and junctional opening. Recently, we found that FAK related non-kinase (FRNK), a protein that is often used as a FAK dominant negative, blocked eosinophil transmigration by preventing the transcription of vascular cell adhesion molecule-1 (VCAM-1) and eotaxin-3 (CCL26). Surprisingly, the blocking occurred even in the absence of endogenous FAK. To better understand the role of FAK in leukocyte recruitment, we used a FAK-specific inhibitor (PF-573228) and determined the effect on IL-4 induced eosinophil recruitment in vitro and in vivo. PF-573228 prevented the expression of VCAM-1 and CCL26 expression in IL-4-stimulated human endothelial cells in vitro. As a result, eosinophil adhesion and transmigration were blocked. PF-572338 also prevented IL-4-induced VCAM-1 expression in vivo. Using brightfield intravital microscopy, we found that PF-573228 decreased leukocyte rolling flux, adhesion, and emigration. We specifically examined eosinophil recruitment in vivo by using an eosinophil-GFP reporter mouse and found PF-573228 attenuated eosinophil emigration. This study reveals that a FAK inhibitor influences inflammation through its action on eosinophil recruitment. ©2018 Society for Leukocyte Biology.

Tuning cell adhesive properties via layer-by-layer assembly of chitosan and alginate

PubMed Central

Silva, Joana M.; García, José R.; Reis, Rui L.; García, Andrés J.; Mano, João F.

2017-01-01

Understanding the mechanisms controlling cell-multilayer film interactions is crucial to the successful engineering of these coatings for biotechnological and biomedical applications. Herein, we present a strategy to tune the cell adhesive properties of multilayers based on marine polysaccharides with and without cross-linking and/or coating with extracellular matrix proteins. Chemical cross-linking of multilayers improved mechanical properties of the coatings but also elicited changes in surface chemistry that alter the adhesion of human umbilical vein endothelial cells. We evaluated a strategy to decouple the mechanical and chemical properties of these films, enabling the transition from cell-adhesive to cell-resistant multilayers. Addition of chitosan/alginate multilayers on top of cross-linked films decreased endothelial cell adhesion, spreading, and proliferation to similar levels as uncross-linked films. Our findings highlight the key role of surface chemistry in cell-multilayer film interactions, and these engineered nanocoatings represent a tunable model of cell adhesive and non-adhesive multilayered films. PMID:28126597

Molecular analysis of antigen-independent adhesion forces between T and B lymphocytes.

PubMed Central

Amblard, F; Auffray, C; Sekaly, R; Fischer, A

1994-01-01

The low-affinity interactions underlying antigen recognition by T-cell receptors (TCRs) are thought to involve antigen-independent adhesion mechanisms. Using a hydrodynamic approach, we found that antigen-independent adhesion occurred between human B cells and resting T cells in a transient and temperature-dependent fashion. The mean cell-cell adhesion force was 0.32 x 10(-9) N and was generated by similar contributions (0.16 x 10(-9) N) of the LFA-1- and CD2-dependent adhesion pathways. After T-cell stimulation with a phorbol ester, the force contributed by LFA-1 was drastically increased, while that of CD2 was unaffected. We propose that weak receptor-mediated adhesion initiates antigen-independent intercellular contacts required for antigen recognition by the TCR and is upregulated following TCR engagement. The method used permits adhesion forces between living cells to be resolved at the molecular level and should prove valuable for the rapid assessment of interaction forces between various types of cells and cell-sized particles. Images PMID:7909604

Neuropeptides, via specific receptors, regulate T cell adhesion to fibronectin.

PubMed

Levite, M; Cahalon, L; Hershkoviz, R; Steinman, L; Lider, O

1998-01-15

The ability of T cells to adhere to and interact with components of the blood vessel walls and the extracellular matrix is essential for their extravasation and migration into inflamed sites. We have found that the beta1 integrin-mediated adhesion of resting human T cells to fibronectin, a major glycoprotein component of the extracellular matrix, is induced by physiologic concentrations of three neuropeptides: calcitonin gene-related protein (CGRP), neuropeptide Y, and somatostatin; each acts via its own specific receptor on the T cell membrane. In contrast, substance P (SP), which coexists with CGRP in the majority of peripheral endings of sensory nerves, including those innervating the lymphoid organs, blocks T cell adhesion to fibronectin when induced by CGRP, neuropeptide Y, somatostatin, macrophage inflammatory protein-1beta, and PMA. Inhibition of T cell adhesion was obtained both by the intact SP peptide and by its 1-4 N-terminal and its 4-11, 5-11, and 6-11 C-terminal fragments, used at similar nanomolar concentrations. The inhibitory effects of the parent SP peptide and its fragments were abrogated by an SP NK-1 receptor antagonist, suggesting they all act through the same SP NK-1 receptor. These findings suggest that neuropeptides, by activating their specific T cell-expressed receptors, can provide the T cells with both positive (proadhesive) and negative (antiadhesive) signals and thereby regulate their function. Thus, neuropeptides may influence diverse physiologic processes involving integrins, including leukocyte-mediated migration and inflammation.

Biofouling in photobioreactors for marine microalgae.

PubMed

Zeriouh, Ouassim; Reinoso-Moreno, José Vicente; López-Rosales, Lorenzo; Cerón-García, María Del Carmen; Sánchez-Mirón, Asterio; García-Camacho, Francisco; Molina-Grima, Emilio

2017-12-01

The economic and/or energetic feasibility of processes based on using microalgae biomass requires an efficient cultivation system. In photobioreactors (PBRs), the adhesion of microalgae to the transparent PBR surfaces leads to biofouling and reduces the solar radiation penetrating the PBR. Light reduction within the PBR decreases biomass productivity and, therefore, the photosynthetic efficiency of the cultivation system. Additionally, PBR biofouling leads to a series of further undesirable events including changes in cell pigmentation, culture degradation, and contamination by invasive microorganisms; all of which can result in the cultivation process having to be stopped. Designing PBR surfaces with proper materials, functional groups or surface coatings, to prevent microalgal adhesion is essential for solving the biofouling problem. Such a significant advance in microalgal biotechnology would enable extended operational periods at high productivity and reduce maintenance costs. In this paper, we review the few systematic studies performed so far and applied the existing thermodynamic and colloidal theories for microbial biofouling formation in order to understand microalgal adhesion on PBR surfaces and the microalgae-microalgae cell interactions. Their relationship to the physicochemical properties of the solid PBR surface, the microalgae cell surfaces, and the ionic strength of the culture medium is discussed. The suitability and the applicability of such theories are reviewed. To this end, an example of biofouling formation on a commercial glass surface is presented for the marine microalgae Nannochloropsis gaditana. It highlights the adhesion dynamics and the inaccuracies of the process and the need for further refinement of previous theories so as to apply them to flowing systems, such as is the case for PBRs used to culture microalgae.

Identification of a Monocyte Receptor on Herpesvirus-Infected Endothelial Cells

NASA Astrophysics Data System (ADS)

Etingin, Orli R.; Silverstein, Roy L.; Hajjar, David P.

1991-08-01

The adhesion of circulating blood cells to vascular endothelium may be an initial step in atherosclerosis, inflammation, and wound healing. One mechanism for promoting cell-cell adhesion involves the expression of adhesion molecules on the surface of the target cell. Herpes simplex virus infection of endothelium induces arterial injury and has been implicated in the development of human atherosclerosis. We now demonstrate that HSV-infected endothelial cells express the adhesion molecule GMP140 and that this requires cell surface expression of HSV glycoprotein C and local thrombin generation. Monocyte adhesion to HSV-infected endothelial cells was completely inhibited by anti-GMP140 antibodies but not by antibodies to other adhesion molecules such as VCAM and ELAM-1. The induction of GMP140 expression on HSV-infected endothelium may be an important pathophysiological mechanism in virus-induced cell injury and inflammation.

Cadherin-23 Mediates Heterotypic Cell-Cell Adhesion between Breast Cancer Epithelial Cells and Fibroblasts

PubMed Central

Apostolopoulou, Maria; Ligon, Lee

2012-01-01

In the early stages of breast cancer metastasis, epithelial cells penetrate the basement membrane and invade the surrounding stroma, where they encounter fibroblasts. Paracrine signaling between fibroblasts and epithelial tumor cells contributes to the metastatic cascade, but little is known about the role of adhesive contacts between these two cell types in metastasis. Here we show that MCF-7 breast cancer epithelial cells and normal breast fibroblasts form heterotypic adhesions when grown together in co-culture, as evidenced by adhesion assays. PCR and immunoblotting show that both cell types express multiple members of the cadherin superfamily, including the atypical cadherin, cadherin-23, when grown in isolation and in co-culture. Immunocytochemistry experiments show that cadherin-23 localizes to homotypic adhesions between MCF-7 cells and also to heterotypic adhesions between the epithelial cells and fibroblasts, and antibody inhibition and RNAi experiments show that cadherin-23 plays a role in mediating these adhesive interactions. Finally, we show that cadherin-23 is upregulated in breast cancer tissue samples, and we hypothesize that heterotypic adhesions mediated by this atypical cadherin may play a role in the early stages of metastasis. PMID:22413011

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.

Chlorella 11-Peptide Inhibits the Production of Macrophage-Induced Adhesion Molecules and Reduces Endothelin-1 Expression and Endothelial Permeability

PubMed Central

Shih, Mei Fen; Chen, Lih Chi; Cherng, Jong Yuh

2013-01-01

The inflammation process in large vessels involves the up-regulation of vascular adhesion molecules such as endothelial cell selectin (E-selectin), intercellular cell adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) which are also known as the markers of atherosclerosis. We have reported that Chlorella 11-peptide exhibited effective anti-inflammatory effects. This peptide with an amino sequence Val-Glu-Cys-Tyr-Gly-Pro-Asn-Arg-Pro-Gln-Phe was further examined for its potential in preventing atherosclerosis in this study. In particular, the roles of Chlorella 11-peptide in lowering the production of vascular adhesion molecules, monocyte chemoattractant protein (MCP-1) and expression of endothelin-1 (ET-1) from endothelia (SVEC4-10 cells) were studied. The production of E-selectin, ICAM-1, VCAM-1 and MCP-1 in SVEC4-10 cells was measured with ELISA. The mRNA expression of ET-1 was analyzed by RT-PCR and agarose gel. Results showed that Chlorella 11-peptide significantly suppressed the levels of E-selectin, ICAM, VCAM, MCP-1 as well as ET-1 gene expression. The inhibition of ICAM-1 and VCAM-1 production by Chlorella 11-peptide was reversed in the presence of protein kinase A inhibitor (H89) which suggests that the cAMP pathway was involved in the inhibitory cause of the peptide. In addition, this peptide was shown to reduce the extent of increased intercellular permeability induced by combination of 50% of lipopolysaccharide (LPS)-activated RAW 264.7 cells medium and 50% normal SEVC cell culture medium (referred to as 50% RAW-conditioned medium). These data demonstrate that Chlorella 11-peptide is a promising biomolecule in preventing chronic inflammatory-related vascular diseases. PMID:24129228

Simple rules for a "simple" nervous system? Molecular and biomathematical approaches to enteric nervous system formation and malformation.

PubMed

Newgreen, Donald F; Dufour, Sylvie; Howard, Marthe J; Landman, Kerry A

2013-10-01

We review morphogenesis of the enteric nervous system from migratory neural crest cells, and defects of this process such as Hirschsprung disease, centering on cell motility and assembly, and cell adhesion and extracellular matrix molecules, along with cell proliferation and growth factors. We then review continuum and agent-based (cellular automata) models with rules of cell movement and logistical proliferation. Both movement and proliferation at the individual cell level are modeled with stochastic components from which stereotyped outcomes emerge at the population level. These models reproduced the wave-like colonization of the intestine by enteric neural crest cells, and several new properties emerged, such as colonization by frontal expansion, which were later confirmed biologically. These models predict a surprising level of clonal heterogeneity both in terms of number and distribution of daughter cells. Biologically, migrating cells form stable chains made up of unstable cells, but this is not seen in the initial model. We outline additional rules for cell differentiation into neurons, axon extension, cell-axon and cell-cell adhesions, chemotaxis and repulsion which can reproduce chain migration. After the migration stage, the cells re-arrange as a network of ganglia. Changes in cell adhesion molecules parallel this, and we describe additional rules based on Steinberg's Differential Adhesion Hypothesis, reflecting changing levels of adhesion in neural crest cells and neurons. This was able to reproduce enteric ganglionation in a model. Mouse mutants with disturbances of enteric nervous system morphogenesis are discussed, and these suggest future refinement of the models. The modeling suggests a relatively simple set of cell behavioral rules could account for complex patterns of morphogenesis. The model has allowed the proposal that Hirschsprung disease is mostly an enteric neural crest cell proliferation defect, not a defect of cell migration. In addition, the model suggests an explanations for zonal and skip segment variants of Hirschsprung disease, and also gives a novel stochastic explanation for the observed discordancy of Hirschsprung disease in identical twins. © 2013 Elsevier Inc. All rights reserved.

Mechanisms of integrin-vascular endothelial growth factor receptor cross-activation in angiogenesis.

PubMed

Mahabeleshwar, Ganapati H; Feng, Weiyi; Reddy, Kumar; Plow, Edward F; Byzova, Tatiana V

2007-09-14

The functional responses of endothelial cells are dependent on signaling from peptide growth factors and the cellular adhesion receptors, integrins. These include cell adhesion, migration, and proliferation, which, in turn, are essential for more complex processes such as formation of the endothelial tube network during angiogenesis. This study identifies the molecular requirements for the cross-activation between beta3 integrin and tyrosine kinase receptor 2 for vascular endothelial growth factor (VEGF) receptor (VEGFR-2) on endothelium. The relationship between VEGFR-2 and beta3 integrin appears to be synergistic, because VEGFR-2 activation induces beta3 integrin tyrosine phosphorylation, which, in turn, is crucial for VEGF-induced tyrosine phosphorylation of VEGFR-2. We demonstrate here that adhesion- and growth factor-induced beta3 integrin tyrosine phosphorylation are directly mediated by c-Src. VEGF-stimulated recruitment and activation of c-Src and subsequent beta3 integrin tyrosine phosphorylation are critical for interaction between VEGFR-2 and beta3 integrin. Moreover, c-Src mediates growth factor-induced beta3 integrin activation, ligand binding, beta3 integrin-dependent cell adhesion, directional migration of endothelial cells, and initiation of angiogenic programming in endothelial cells. Thus, the present study determines the molecular mechanisms and consequences of the synergism between 2 cell surface receptor systems, growth factor receptor and integrins, and opens new avenues for the development of pro- and antiangiogenic strategies.

Molecular signaling in live cells studied by FRET

NASA Astrophysics Data System (ADS)

Chien, Shu; Wang, Yingxiao

2011-11-01

Genetically encoded biosensors based on fluorescence resonance energy transfer (FRET) enables visualization of signaling events in live cells with high spatiotemporal resolution. We have used FRET to assess temporal and spatial characteristics for signaling molecules, including tyrosine kinases Src and FAK, small GTPase Rac, calcium, and a membrane-bound matrix metalloproteinase MT1-MMP. Activations of Src and Rac by platelet derived growth factor (PDGF) led to distinct subcellular patterns during cell migration on micropatterned surface, and these two enzymes interact with each other to form a feedback loop with differential regulations at different subcellular locations. We have developed FRET biosensors to monitor FAK activities at rafts vs. non-raft regions of plasma membrane in live cells. In response to cell adhesion on matrix proteins or stimulation by PDGF, the raft-targeting FAK biosensor showed a stronger FRET response than that at non-rafts. The FAK activation at rafts induced by PDGF is mediated by Src. In contrast, the FAK activation at rafts induced by adhesion is independent of Src activity, but rather is essential for Src activation. Thus, Src is upstream to FAK in response to chemical stimulation (PDGF), but FAK is upstream to Src in response to mechanical stimulation (adhesion). A novel biosensor has been developed to dynamically visualize the activity of membrane type-1-matrix metalloproteinase (MT1-MMP), which proteolytically remodels the extracellular matrix. Epidermal growth factor (EGF) directed active MT1-MMP to the leading edge of migrating live cancer cells with local accumulation of EGF receptor via a process dependent on an intact cytoskeletal network. In summary, FRET-based biosensors enable the elucidation of molecular processes and hierarchies underlying spatiotemporal regulation of biological and pathological processes, thus advancing our knowledge on how cells perceive mechanical/chemical cues in space and time to coordinate molecular/cellular functions.

Molecular signaling in live cells studied by FRET

NASA Astrophysics Data System (ADS)

Chien, Shu; Wang, Yingxiao

2012-03-01

Genetically encoded biosensors based on fluorescence resonance energy transfer (FRET) enables visualization of signaling events in live cells with high spatiotemporal resolution. We have used FRET to assess temporal and spatial characteristics for signaling molecules, including tyrosine kinases Src and FAK, small GTPase Rac, calcium, and a membrane-bound matrix metalloproteinase MT1-MMP. Activations of Src and Rac by platelet derived growth factor (PDGF) led to distinct subcellular patterns during cell migration on micropatterned surface, and these two enzymes interact with each other to form a feedback loop with differential regulations at different subcellular locations. We have developed FRET biosensors to monitor FAK activities at rafts vs. non-raft regions of plasma membrane in live cells. In response to cell adhesion on matrix proteins or stimulation by PDGF, the raft-targeting FAK biosensor showed a stronger FRET response than that at non-rafts. The FAK activation at rafts induced by PDGF is mediated by Src. In contrast, the FAK activation at rafts induced by adhesion is independent of Src activity, but rather is essential for Src activation. Thus, Src is upstream to FAK in response to chemical stimulation (PDGF), but FAK is upstream to Src in response to mechanical stimulation (adhesion). A novel biosensor has been developed to dynamically visualize the activity of membrane type-1-matrix metalloproteinase (MT1-MMP), which proteolytically remodels the extracellular matrix. Epidermal growth factor (EGF) directed active MT1-MMP to the leading edge of migrating live cancer cells with local accumulation of EGF receptor via a process dependent on an intact cytoskeletal network. In summary, FRET-based biosensors enable the elucidation of molecular processes and hierarchies underlying spatiotemporal regulation of biological and pathological processes, thus advancing our knowledge on how cells perceive mechanical/chemical cues in space and time to coordinate molecular/cellular functions.

Molecules mediating adhesion of T and B cells, monocytes and granulocytes to vascular endothelial cells.

PubMed Central

Prieto, J; Beatty, P G; Clark, E A; Patarroyo, M

1988-01-01

Leucocytes interact with vascular endothelial cells (EC), and adhesion between these two cell types in vitro is modulated by phorbol ester. Monocytes were found to display the highest basal adhesion to EC, followed by Epstein-Barr virus-immortalized normal B cells (EBV-B), T cells and granulocytes. Phorbol ester treatment increased the adhesion of all types of leucocytes, except monocytes. In the presence of this compound, monoclonal antibody 60.3 to GP90 (CD18, a leucocyte-adhesion protein which is non-covalently associated to either GP160, GP155, or GP130) was found to inhibit the adhesion of the four types of leucocytes to a considerable extent, while anti-lymphocyte function-associated antigen-1 (LFA-1) antibody to GP160 (CD11a) inhibited the adhesion of T and B cells only. Antibody 60.1 to GP155 (CD11b) had a major inhibitory activity exclusively on granulocytes, while antibody LB-2, which recognizes a distinct adhesion molecule (GP84) and, in contrast to the previous antibodies, reacts with EC, mainly inhibited adhesion of EBV-B and did not increase the inhibition obtained with antibody 60.3 alone. Fab fragments of antibody 60.3 inhibited leucocyte adhesion more efficiently, in either the absence or presence of phorbol ester, than the intact antibody molecule. It is concluded the GP90, either alone or associated to the larger glycoproteins, mediates the adhesion in all types of leucocytes, while GP84 mediates the adhesion of the activated B cells. Images Figure 2 PMID:3259203

Circulating vascular cell adhesion molecule-1 in pre-eclampsia, gestational hypertension, and normal pregnancy: evidence of selective dysregulation of vascular cell adhesion molecule-1 homeostasis in pre-eclampsia.

PubMed

Higgins, J R; Papayianni, A; Brady, H R; Darling, M R; Walshe, J J

1998-08-01

Our purpose was to investigate circulating levels of vascular cell adhesion molecule-1 in the peripheral and uteroplacental circulations during normotensive and hypertensive pregnancies. This prospective observational study involved 2 patient groups. Group 1 consisted of 22 women with pre-eclampsia and 30 normotensive women followed up longitudinally through pregnancy and post partum. There were an additional 13 women with established gestational hypertension. Group 2 consisted of 20 women with established pre-eclampsia and 19 normotensive control subjects undergoing cesarean delivery. Plasma levels of vascular cell adhesion molecule-1 were measured in blood drawn from the antecubital vein (group 1) and from both the antecubital and uterine veins (group 2). Data were analyzed by analysis of variance. In group 1 vascular cell adhesion molecule-1 levels did not change significantly throughout normal pregnancy and post partum. Women with established pre-eclampsia had increased vascular cell adhesion molecule-1 levels compared with the normotensive pregnancy group (P = .01). Vascular cell adhesion molecule-1 levels were not elevated in women with established gestational hypertension. In group 2 significantly higher levels of vascular cell adhesion molecule-1 were detected in the uteroplacental (P < .0001) and peripheral (P < .0001) circulations of pre-eclamptic women by comparison with normotensive women. In the pre-eclamptic group there was a tendency toward higher vascular cell adhesion molecule-1 levels in the peripheral circulation than in the uteroplacental circulation (P = .06). In contrast to vascular cell adhesion molecule-1, circulating levels of E-selectin and intercellular adhesion molecule-1, other major leukocyte adhesion molecules expressed by the endothelium, were not different in pre-eclamptic and normotensive pregnancies. Established pre-eclampsia is characterized by selective dysregulation of vascular cell adhesion molecule-1 homeostasis. This event is not an early preclinical feature of pre-eclampsia, does not persist post partum, is not a feature of nonproteinuric gestational hypertension, and is not observed with other major leukocyte adhesion molecules. Induction of vascular cell adhesion molecule-1 expression in pre-eclampsia may contribute to leukocyte-mediated tissue injury in this condition or may reflect perturbation of other, previously unrecognized, functions of this molecule in pregnancy.

Sickle red cell-endothelium interactions.

PubMed

Kaul, Dhananjay K; Finnegan, Eileen; Barabino, Gilda A

2009-01-01

Periodic recurrence of painful vaso-occlusive crisis is the defining feature of sickle cell disease. Among multiple pathologies associated with this disease, sickle red cell-endothelium interaction has been implicated as a potential initiating mechanism in vaso-occlusive events. This review focuses on various interrelated mechanisms involved in human sickle red cell adhesion. We discuss in vitro and microcirculatory findings on sickle red cell adhesion, its potential role in vaso-occlusion, and the current understanding of receptor-ligand interactions involved in this pathological phenomenon. In addition, we discuss the contribution of other cellular interactions (leukocytes recruitment and leukocyte-red cell interaction) to vaso-occlusion, as observed in transgenic sickle mouse models. Emphasis is given to recently discovered adhesion molecules that play a predominant role in mediating human sickle red cell adhesion. Finally, we analyze various therapeutic approaches for inhibiting sickle red cell adhesion by targeting adhesion molecules and also consider therapeutic strategies that target stimuli involved in endothelial activation and initiation of adhesion.

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

Centrifugation assay for measuring adhesion of serially passaged bovine chondrocytes to polystyrene surfaces.

PubMed

Kaplan, David S; Hitchins, Victoria M; Vegella, Thomas J; Malinauskas, Richard A; Ferlin, Kimberly M; Fisher, John P; Frondoza, Carmelita G

2012-07-01

A major obstacle in chondrocyte-based therapy for cartilage repair is the limited availability of cells that maintain their original phenotype. Propagation of chondrocytes as monolayer cultures on polystyrene surfaces is used extensively for amplifying cell numbers. However, chondrocytes undergo a phenotypic shift when propagated in this manner and display characteristics of more adherent fibroblastic cells. Little information is available about the effect of this phenotypic shift on cellular adhesion properties. We evaluated changes in adhesion property as bovine chondrocytes were serially propagated up to five passages in monolayer culture using a centrifugation cell adhesion assay, which was based on counting of cells before and after being exposed to centrifugal dislodgement forces of 120 and 350 g. Chondrocytes proliferated well in a monolayer culture with doubling times of 2-3 days, but they appeared more fibroblastic and exhibited elongated cell morphology with continued passage. The centrifugation cell adhesion assay showed that chondrocytes became more adhesive with passage as the percentage of adherent cells after centrifugation increased and was not statistically different from the adhesion of the fibroblast cell line, L929, starting at passage 3. This increased adhesiveness correlated with a shift to a fibroblastic morphology and increased collagen I mRNA expression starting at passage 2. Our findings indicate that the centrifugation cell adhesion assay may serve as a reproducible tool to track alterations in chondrocyte phenotype during their extended propagation in culture.

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

The effect of the physical properties of the substrate on the kinetics of cell adhesion and crawling studied by an axisymmetric diffusion-energy balance coupled model.

PubMed

Samadi-Dooki, Aref; Shodja, Hossein M; Malekmotiei, Leila

2015-05-14

In this paper an analytical approach to study the effect of the substrate physical properties on the kinetics of adhesion and motility behavior of cells is presented. Cell adhesion is mediated by the binding of cell wall receptors and substrate's complementary ligands, and tight adhesion is accomplished by the recruitment of the cell wall binders to the adhesion zone. The binders' movement is modeled as their axisymmetric diffusion in the fluid-like cell membrane. In order to preserve the thermodynamic consistency, the energy balance for the cell-substrate interaction is imposed on the diffusion equation. Solving the axisymmetric diffusion-energy balance coupled equations, it turns out that the physical properties of the substrate (substrate's ligand spacing and stiffness) have considerable effects on the cell adhesion and motility kinetics. For a rigid substrate with uniform distribution of immobile ligands, the maximum ligand spacing which does not interrupt adhesion growth is found to be about 57 nm. It is also found that as a consequence of the reduction in the energy dissipation in the isolated adhesion system, cell adhesion is facilitated by increasing substrate's stiffness. Moreover, the directional movement of cells on a substrate with gradients in mechanical compliance is explored with an extension of the adhesion formulation. It is shown that cells tend to move from soft to stiff regions of the substrate, but their movement is decelerated as the stiffness of the substrate increases. These findings based on the proposed theoretical model are in excellent agreement with the previous experimental observations.

Roles of ion transport in control of cell motility.

PubMed

Stock, Christian; Ludwig, Florian T; Hanley, Peter J; Schwab, Albrecht

2013-01-01

Cell motility is an essential feature of life. It is essential for reproduction, propagation, embryonic development, and healing processes such as wound closure and a successful immune defense. If out of control, cell motility can become life-threatening as, for example, in metastasis or autoimmune diseases. Regardless of whether ciliary/flagellar or amoeboid movement, controlled motility always requires a concerted action of ion channels and transporters, cytoskeletal elements, and signaling cascades. Ion transport across the plasma membrane contributes to cell motility by affecting the membrane potential and voltage-sensitive ion channels, by inducing local volume changes with the help of aquaporins and by modulating cytosolic Ca(2+) and H(+) concentrations. Voltage-sensitive ion channels serve as voltage detectors in electric fields thus enabling galvanotaxis; local swelling facilitates the outgrowth of protrusions at the leading edge while local shrinkage accompanies the retraction of the cell rear; the cytosolic Ca(2+) concentration exerts its main effect on cytoskeletal dynamics via motor proteins such as myosin or dynein; and both, the intracellular and the extracellular H(+) concentration modulate cell migration and adhesion by tuning the activity of enzymes and signaling molecules in the cytosol as well as the activation state of adhesion molecules at the cell surface. In addition to the actual process of ion transport, both, channels and transporters contribute to cell migration by being part of focal adhesion complexes and/or physically interacting with components of the cytoskeleton. The present article provides an overview of how the numerous ion-transport mechanisms contribute to the various modes of cell motility.

Proton beam writing of microstructures in Agar gel for patterned cell growth

NASA Astrophysics Data System (ADS)

Larisch, Wolfgang; Koal, Torsten; Werner, Ronald; Hohlweg, Marcus; Reinert, Tilo; Butz, Tilman

2011-10-01

A rather useful prerequisite for many biological and biophysical studies, e.g., for cell-cell communication or neuronal networks, is confined cell growth on micro-structured surfaces. Solidified Agar layers have smooth surfaces which are electrically neutral and thus inhibit receptor binding and cell adhesion. For the first time, Agar microstructures have been manufactured using proton beam writing (PBW). In the irradiated Agar material the polysaccharides are split into oligosaccharides which can easily be washed off leaving Agar-free areas for cell adhesion. The beam diameter of 1 μm allows the fabrication of compartments accommodating single cells which are connected by micrometer-sized channels. Using the external beam the production process is very fast. Up to 50 Petri dishes can be produced per day which makes this technique very suitable for biological investigations which require large throughputs.

Silver deposition on titanium surface by electrochemical anodizing process reduces bacterial adhesion of Streptococcus sanguinis and Lactobacillus salivarius.

PubMed

Godoy-Gallardo, Maria; Rodríguez-Hernández, Ana G; Delgado, Luis M; Manero, José M; Javier Gil, F; Rodríguez, Daniel

2015-10-01

The aim of this study was to determine the antibacterial properties of silver-doped titanium surfaces prepared with a novel electrochemical anodizing process. Titanium samples were anodized with a pulsed process in a solution of silver nitrate and sodium thiosulphate at room temperature with stirring. Samples were processed with different electrolyte concentrations and treatment cycles to improve silver deposition. Physicochemical properties were determined by X-ray photoelectron spectroscopy, contact angle measurements, white-light interferometry, and scanning electron microscopy. Cellular cytotoxicity in human fibroblasts was studied with lactate dehydrogenase assays. The in vitro effect of treated surfaces on two oral bacteria strains (Streptococcus sanguinis and Lactobacillus salivarius) was studied with viable bacterial adhesion measurements and growth curve assays. Nonparametric statistical Kruskal-Wallis and Mann-Whitney U-tests were used for multiple and paired comparisons, respectively. Post hoc Spearman's correlation tests were calculated to check the dependence between bacteria adhesion and surface properties. X-ray photoelectron spectroscopy results confirmed the presence of silver on treated samples and showed that treatments with higher silver nitrate concentration and more cycles increased the silver deposition on titanium surface. No negative effects in fibroblast cell viability were detected and a significant reduction on bacterial adhesion in vitro was achieved in silver-treated samples compared with control titanium. Silver deposition on titanium with a novel electrochemical anodizing process produced surfaces with significant antibacterial properties in vitro without negative effects on cell viability. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A critical role of platelet adhesion in the initiation of atherosclerotic lesion formation.

PubMed

Massberg, Steffen; Brand, Korbinian; Grüner, Sabine; Page, Sharon; Müller, Elke; Müller, Iris; Bergmeier, Wolfgang; Richter, Thomas; Lorenz, Michael; Konrad, Ildiko; Nieswandt, Bernhard; Gawaz, Meinrad

2002-10-07

The contribution of platelets to the process of atherosclerosis remains unclear. Here, we show in vivo that platelets adhere to the vascular endothelium of the carotid artery in ApoE(-)(/)(-) mice before the development of manifest atherosclerotic lesions. Platelet-endothelial cell interaction involved both platelet glycoprotein (GP)Ibalpha and GPIIb-IIIa. Platelet adhesion to the endothelium coincides with inflammatory gene expression and preceded atherosclerotic plaque invasion by leukocytes. Prolonged blockade of platelet adhesion in ApoE(-)(/)(-) mice profoundly reduced leukocyte accumulation in the arterial intima and attenuated atherosclerotic lesion formation in the carotid artery bifurcation, the aortic sinus, and the coronary arteries. These findings establish the platelet as a major player in initiation of the atherogenetic process.

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.

Interaction of tumor and host cells with adhesion and extracellular matrix molecules in the development of multiple myeloma.

PubMed

Teoh, G; Anderson, K C

1997-02-01

Adhesion molecules play an important role in the growth regulation and migration of multiple myeloma (MM) cells. They mediate homing of MM cells to the bone marrow and MM cell to bone marrow stromal cell adhesion, with resultant interleukin-6 related autocrine and paracine growth and antiapoptotic affects. Their pattern of expression on tumor cells correlates with the development of plasma cell leukemia or extramedullary disease. Clinically, expression of adhesion molecules on tumor cells or in the serum has already shown prognostic utility. Finally, since adhesion molecules are involved at multiple steps in the pathogenesis of MM, therapeutic studies may target these molecules.

Integrins are required for tissue organization and restriction of neurogenesis in regenerating planarians

PubMed Central

Seebeck, Florian; März, Martin; Meyer, Anna-Wiebke; Reuter, Hanna; Vogg, Matthias C.; Stehling, Martin; Mildner, Karina; Zeuschner, Dagmar; Rabert, Franziska

2017-01-01

Tissue regeneration depends on proliferative cells and on cues that regulate cell division, differentiation, patterning and the restriction of these processes once regeneration is complete. In planarians, flatworms with high regenerative potential, muscle cells express some of these instructive cues. Here, we show that members of the integrin family of adhesion molecules are required for the integrity of regenerating tissues, including the musculature. Remarkably, in regenerating β1-integrin RNAi planarians, we detected increased numbers of mitotic cells and progenitor cell types, as well as a reduced ability of stem cells and lineage-restricted progenitor cells to accumulate at wound sites. These animals also formed ectopic spheroid structures of neural identity in regenerating heads. Interestingly, those polarized assemblies comprised a variety of neural cells and underwent continuous growth. Our study indicates that integrin-mediated cell adhesion is required for the regenerative formation of organized tissues and for restricting neurogenesis during planarian regeneration. PMID:28137894

Effect of graphene oxide ratio on the cell adhesion and growth behavior on a graphene oxide-coated silicon substrate

NASA Astrophysics Data System (ADS)

Jeong, Jin-Tak; Choi, Mun-Ki; Sim, Yumin; Lim, Jung-Taek; Kim, Gil-Sung; Seong, Maeng-Je; Hyung, Jung-Hwan; Kim, Keun Soo; Umar, Ahmad; Lee, Sang-Kwon

2016-09-01

Control of living cells on biocompatible materials or on modified substrates is important for the development of bio-applications, including biosensors and implant biomaterials. The topography and hydrophobicity of substrates highly affect cell adhesion, growth, and cell growth kinetics, which is of great importance in bio-applications. Herein, we investigate the adhesion, growth, and morphology of cultured breast cancer cells on a silicon substrate, on which graphene oxides (GO) was partially formed. By minimizing the size and amount of the GO-containing solution and the further annealing process, GO-coated Si samples were prepared which partially covered the Si substrates. The coverage of GO on Si samples decreases upon annealing. The behaviors of cells cultured on two samples have been observed, i.e. partially GO-coated Si (P-GO) and annealed partially GO-coated Si (Annealed p-GO), with a different coverage of GO. Indeed, the spreading area covered by the cells and the number of cells for a given culture period in the incubator were highly dependent on the hydrophobicity and the presence of oxygenated groups on GO and Si substrates, suggesting hydrophobicity-driven cell growth. Thus, the presented method can be used to control the cell growth via an appropriate surface modification.

The molecular mechanism of mediation of adsorbed serum proteins to endothelial cells adhesion and growth on biomaterials.

PubMed

Yang, Dayun; Lü, Xiaoying; Hong, Ying; Xi, Tingfei; Zhang, Deyuan

2013-07-01

To explore molecular mechanism of mediation of adsorbed proteins to cell adhesion and growth on biomaterials, this study examined endothelial cell adhesion, morphology and viability on bare and titanium nitride (TiN) coated nickel titanium (NiTi) alloys and chitosan film firstly, and then identified the type and amount of serum proteins adsorbed on the three surfaces by proteomic technology. Subsequently, the mediation role of the identified proteins to cell adhesion and growth was investigated with bioinformatics analyses, and further confirmed by a series of cellular and molecular biological experiments. Results showed that the type and amount of adsorbed serum proteins associated with cell adhesion and growth was obviously higher on the alloys than on the chitosan film, and these proteins mediated endothelial cell adhesion and growth on the alloys via four ways. First, proteins such as adiponectin in the adsorbed protein layer bound with cell surface receptors to generate signal transduction, which activated cell surface integrins through increasing intracellular calcium level. Another way, thrombospondin 1 in the adsorbed protein layer promoted TGF-β signaling pathway activation and enhanced integrins expression. The third, RGD sequence containing proteins such as fibronectin 1, vitronectin and thrombospondin 1 in the adsorbed protein layer bound with activated integrins to activate focal adhesion pathway, increased focal adhesion formation and actin cytoskeleton organization and mediated cell adhesion and spreading. In addition, the activated focal adhesion pathway promoted the expression of cell growth related genes and resulted in cell proliferation. The fourth route, coagulation factor II (F2) and fibronectin 1 in the adsorbed protein layer bound with cell surface F2 receptor and integrin, activated regulation of actin cytoskeleton pathway and regulated actin cytoskeleton organization. Copyright © 2013 Elsevier Ltd. All rights reserved.

Inositol pyrophosphates promote tumor growth and metastasis by antagonizing liver kinase B1

PubMed Central

Rao, Feng; Xu, Jing; Fu, Chenglai; Cha, Jiyoung Y.; Gadalla, Moataz M.; Xu, Risheng; Barrow, James C.; Snyder, Solomon H.

2015-01-01

The inositol pyrophosphates, molecular messengers containing an energetic pyrophosphate bond, impact a wide range of biologic processes. They are generated primarily by a family of three inositol hexakisphosphate kinases (IP6Ks), the principal product of which is diphosphoinositol pentakisphosphate (IP7). We report that IP6K2, via IP7 synthesis, is a major mediator of cancer cell migration and tumor metastasis in cell culture and in intact mice. IP6K2 acts by enhancing cell-matrix adhesion and decreasing cell–cell adhesion. This action is mediated by IP7-elicited nuclear sequestration and inactivation of the tumor suppressor liver kinase B1 (LKB1). Accordingly, inhibitors of IP6K2 offer promise in cancer therapy. PMID:25617365

The influence of surface carbohydrates during in vitro infection of mammalian cells by the dermatophyte Trichophyton rubrum.

PubMed

Esquenazi, Daniele; Alviano, Celuta S; de Souza, Wanderley; Rozental, Sonia

2004-04-01

In order to better understand the role played by surface glycoconjugates during host cell adhesion and endocytosis of Trichophyton rubrum, we looked for the presence of carbohydrate-binding adhesins on the microconidia surface and their role on cellular interaction with epithelial and macrophages cells. The interaction of T. rubrum with chinese hamster ovary epithelial cells and their glycosylation-deficient mutants demonstrated a higher adhesion index in Lec1 and Lec2 mutants, that express mannose and galactose, respectively. Endocytosed fungi were shown preferentially in Lec2 cells. Addition of the carbohydrates to the interaction medium, pretreatment with lectins and with sodium periodate decreased the adhesion and endocytic index for all mutants. The ability of the fungus to penetrate into mammalian cells was confirmed in experiments using macrophages treated with cytochalasin D. Flow cytometric analysis showed that this fungus recognizes mannose and galactose. The binding was inhibited by the addition of methyl alpha-D-mannopyranoside and methyl alpha-D-galactopyranoside, and showed higher fluorescence intensity at 37 than at 28 degrees C. Trypsin treatment and heating of the cells reduced the binding, suggesting a (glyco) protein nature for the microconidia adhesins. The presence of lectin-like molecules in fungus cell could be observed by scanning electron microscopy of the fungus incubated with colloidal-gold labeled neoglycoproteins. Our results suggest that T. rubrum has the ability to invade mammalian cells and expresses carbohydrate-specific adhesins on microconidia surface that recognize mannose and galactose. These adhesins may play an important role on the adhesion and invasion of the fungus during the infectious process of dermatophytosis.

Atomic Force Microscopy Mechanical Mapping of Micropatterned Cells Shows Adhesion Geometry-Dependent Mechanical Response on Local and Global Scales

PubMed Central

Rigato, Annafrancesca; Rico, Felix; Eghiaian, Frédéric; Piel, Mathieu; Scheuring, Simon

2015-01-01

In multicellular organisms cell shape and organization are dictated by cell-cell or cell-extracellular matrix adhesion interactions. Adhesion complexes crosstalk with the cytoskeleton enabling cells to sense their mechanical environment. Unfortunately, most of cell biology studies, and cell mechanics studies in particular, are conducted on cultured cells adhering to a hard, homogeneous and unconstrained substrate with non-specific adhesion sites – thus far from physiological and reproducible conditions. Here, we grew cells on three different fibronectin patterns with identical overall dimensions but different geometries (▽, T and Y), and investigated their topography and mechanics by atomic force microscopy (AFM). The obtained mechanical maps were reproducible for cells grown on patterns of the same geometry, revealing pattern-specific subcellular differences. We found that local Young’s moduli variations are related to the cell adhesion geometry. Additionally, we detected local changes of cell mechanical properties induced by cytoskeletal drugs. We thus provide a method to quantitatively and systematically investigate cell mechanics and their variations, and present further evidence for a tight relation between cell adhesion and mechanics. PMID:26013956

Atomic Force Microscopy Mechanical Mapping of Micropatterned Cells Shows Adhesion Geometry-Dependent Mechanical Response on Local and Global Scales.

PubMed

Rigato, Annafrancesca; Rico, Felix; Eghiaian, Frédéric; Piel, Mathieu; Scheuring, Simon

2015-06-23

In multicellular organisms, cell shape and organization are dictated by cell-cell or cell-extracellular matrix adhesion interactions. Adhesion complexes crosstalk with the cytoskeleton enabling cells to sense their mechanical environment. Unfortunately, most of cell biology studies, and cell mechanics studies in particular, are conducted on cultured cells adhering to a hard, homogeneous, and unconstrained substrate with nonspecific adhesion sites, thus far from physiological and reproducible conditions. Here, we grew cells on three different fibronectin patterns with identical overall dimensions but different geometries (▽, T, and Y), and investigated their topography and mechanics by atomic force microscopy (AFM). The obtained mechanical maps were reproducible for cells grown on patterns of the same geometry, revealing pattern-specific subcellular differences. We found that local Young's moduli variations are related to the cell adhesion geometry. Additionally, we detected local changes of cell mechanical properties induced by cytoskeletal drugs. We thus provide a method to quantitatively and systematically investigate cell mechanics and their variations, and present further evidence for a tight relation between cell adhesion and mechanics.

Src homology 2-domain containing leukocyte-specific phosphoprotein of 76 kDa is mandatory for TCR-mediated inside-out signaling, but dispensable for CXCR4-mediated LFA-1 activation, adhesion, and migration of T cells.

PubMed

Horn, Jessica; Wang, Xiaoqian; Reichardt, Peter; Stradal, Theresia E; Warnecke, Nicole; Simeoni, Luca; Gunzer, Matthias; Yablonski, Deborah; Schraven, Burkhart; Kliche, Stefanie

2009-11-01

Engagement of the TCR or of chemokine receptors such as CXCR4 induces adhesion and migration of T cells via so-called inside-out signaling pathways. The molecular processes underlying inside-out signaling events are as yet not completely understood. In this study, we show that TCR- and CXCR4-mediated activation of integrins critically depends on the membrane recruitment of the adhesion- and degranulation-promoting adapter protein (ADAP)/Src kinase-associated phosphoprotein of 55 kDa (SKAP55)/Rap1-interacting adapter protein (RIAM)/Rap1 module. We further demonstrate that the Src homology 2 domain containing leukocyte-specific phosphoprotein of 76 kDa (SLP76) is crucial for TCR-mediated inside-out signaling and T cell/APC interaction. Besides facilitating membrane recruitment of ADAP, SKAP55, and RIAM, SLP76 regulates TCR-mediated inside-out signaling by controlling the activation of Rap1 as well as Rac-mediated actin polymerization. Surprisingly, however, SLP76 is not mandatory for CXCR4-mediated inside-out signaling. Indeed, both CXCR4-induced T cell adhesion and migration are not affected by loss of SLP76. Moreover, after CXCR4 stimulation, the ADAP/SKAP55/RIAM/Rap1 module is recruited to the plasma membrane independently of SLP76. Collectively, our data indicate a differential requirement for SLP76 in TCR- vs CXCR4-mediated inside-out signaling pathways regulating T cell adhesion and migration.

Fyn kinase genetic ablation causes structural abnormalities in mature retina and defective Müller cell function.

PubMed

Chavez-Solano, Marbella; Ibarra-Sanchez, Alfredo; Treviño, Mario; Gonzalez-Espinosa, Claudia; Lamas, Monica

2016-04-01

Fyn kinase is widely expressed in neuronal and glial cells of the brain, where it exerts multiple functional roles that affect fundamental physiological processes. The aim of our study was to investigate the, so far unknown, functional role of Fyn in the retina. We report that Fyn is expressed, in vivo, in a subpopulation of Müller glia. We used a mouse model of Fyn genetic ablation and Müller-enriched primary cultures to demonstrate that Fyn deficiency induces morphological alterations in the mature retina, a reduction in the thickness of the outer and inner nuclear layers and alterations in postnatal Müller cell physiology. These include shortening of Müller cell processes, a decrease in cell proliferation, inactivation of the Akt signal transduction pathway, a reduced number of focal adhesions points and decreased adhesion of these cells to the ECM. As abnormalities in Müller cell physiology have been previously associated to a compromised retinal function we evaluated behavioral responses to visual stimulation. Our results associate Fyn deficiency with impaired visual optokinetic responses under scotopic and photopic light conditions. Our study reveals novel roles for Fyn kinase in retinal morphology and Müller cell physiology and suggests that Fyn is required for optimal visual processing. Copyright © 2016 Elsevier Inc. All rights reserved.

Blocking hepatic metastases of colon cancer cells using an shRNA against Rac1 delivered by activatable cell-penetrating peptide.

PubMed

Bao, Ying; Guo, Huihui; Lu, Yongliang; Feng, Wenming; Sun, Xinrong; Tang, Chengwu; Wang, Xiang; Shen, Mo

2016-11-22

Hepatic metastasis is one of the critical progressions of colon cancer. Blocking this process is key to prolonging survival time in cancer patients. Studies on activatable cell-penetrating peptides (dtACPPs) have demonstrated their potential as gene carriers. It showed high tumor cell-targeting specificity and transfection efficiency and low cytotoxicity in the in vitro settings of drug delivery. However, using this system to silence target genes to inhibit metastasis in colorectal cancer cells has not been widely reported and requires further investigation. In this study, we observed that expression of Rac1, a key molecule for cytoskeletal reorganization, was higher in hepatic metastatic tumor tissue compared with prime colon cancer tissue and that patients with high Rac1-expressing colon cancer showed shorter survival time. Base on these findings, we created dtACPP-PEG-DGL (dtACPPD)/shRac1 nanoparticles and demonstrated that they downregulated Rac1 expression in colon cancer cells. Moreover, we observed inhibitory effects on migration, invasion and adhesion in HCT116 colorectal cancer cells in vitro, and our results showed that Rac1 regulated colon cancer cell matrix adhesion through the regulation of cytofilament dynamics. Moreover, mechanically, repression of Rac1 inhibiting cells migration and invasion by enhancing cell to cell adhesion and reducing cell to extracellular matrix adhesion. Furthermore, when atCDPPD/shRac1 nanoparticles were administered intravenously to a HCT116 xenograft model, significant tumor metastasis to the liver was inhibited. Our results suggest that atCDPP/shRac1 nanoparticles may enable the blockade of hepatic metastasis in colon cancer.

Emergence of collective propulsion through cell-cell adhesion.

PubMed

Matsushita, Katsuyoshi

2018-04-01

The mechanisms driving the collective movement of cells remain poorly understood. To contribute toward resolving this mystery, a model was formulated to theoretically explore the possible functions of polarized cell-cell adhesion in collective cell migration. The model consists of an amoeba cell with polarized cell-cell adhesion, which is controlled by positive feedback with cell motion. This model cell has no persistent propulsion and therefore exhibits a simple random walk when in isolation. However, at high density, these cells acquire collective propulsion and form ordered movement. This result suggests that cell-cell adhesion has a potential function, which induces collective propulsion with persistence.

Emergence of collective propulsion through cell-cell adhesion

NASA Astrophysics Data System (ADS)

Matsushita, Katsuyoshi

2018-04-01

The mechanisms driving the collective movement of cells remain poorly understood. To contribute toward resolving this mystery, a model was formulated to theoretically explore the possible functions of polarized cell-cell adhesion in collective cell migration. The model consists of an amoeba cell with polarized cell-cell adhesion, which is controlled by positive feedback with cell motion. This model cell has no persistent propulsion and therefore exhibits a simple random walk when in isolation. However, at high density, these cells acquire collective propulsion and form ordered movement. This result suggests that cell-cell adhesion has a potential function, which induces collective propulsion with persistence.

Preferential adhesion of surface groups of Bacillus subtilis on gibbsite at different ionic strengths and pHs revealed by ATR-FTIR spectroscopy.

PubMed

Hong, Zhi-Neng; Jiang, Jun; Li, Jiu-Yu; Xu, Ren-Kou

2018-05-01

Adhesion of bacteria onto minerals is a ubiquitous process that plays a central role in many biogeochemical, microbiology and environmental processes in soil and sediment. Although bacterial adhesion onto soil minerals such as phyllosilicates and Fe-oxides have been investigated extensively, little is known about the mechanisms for bacterial attachment onto Al-oxides. Here, we explored the adhesion of Bacillus subtilis onto gibbsite (γ-AlOOH) under various ionic strengths (1, 10, 50, and 100 mM NaCl) and pHs (pH 4, 7, and 9) by in-situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The time evolution of the peak intensities of the attached bacteria suggested that the adhesion underwent an initial rapid reaction followed by a slow pseudo-first-order kinetic stage. Spectral comparison between the attached and free cells, together with the interaction energy calculated with the Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory and the micro-morphology of bacteria-gibbsite complexes, indicated that both electrostatic and chemical (bacterial groups such as phosphate and carboxyl covalently bind to gibbsite) interactions participated in the adhesion processes. Both solution ionic strength (IS) and pH impacted the spectra of attached bacteria, but the peak intensity of different bands changed differently with these two factors, showing a preferential adhesion of surface groups (phosphate, carboxyl, and amide groups) on gibbsite at different conditions. The diverse responses to IS and pH alteration of the forces (chemical bonds, electrostatic attractions, and the hydrophobic interactions) that essentially govern the adhesion might be responsible for the preferential adhesion. These results may help to better understand how bacteria adhere onto soil oxides at molecular scales. Copyright © 2018 Elsevier B.V. All rights reserved.

Morphological responses of dissociated sponge cells to different organic substrata.

PubMed

Gaino, E; Magnino, G; Burlando, B; Sara', M

1993-06-01

To study interactions between sponge cells and components of the extracellular matrix (ECM), cells of the calcareous sponge Clathrina cerebrum were investigated in vitro by scanning electron microscopy. Cells were settled on glass coverslips, used as controls, and on coverslips coated with various ECM components (laminin, collagens and fibronectin), and with an adhesive substance (polylysine). Cells tended to conserve a rounded shape, producing thin, stiff processes (scleropodia) and lamellipodia, whose shape and extension varied according to the substrata. Spreading was observed only on polylysine, inducing cells to assume a fibroblast-like aspect. On laminin, cell adhesion was assured only by scleropodia. On fibronectin, scleropodia and lamellipodia were present, but reduced in size and length. On collagens, laminar processes occurred among prevailing scleropodia. Measurements of cell area and perimeter allowed statistical comparison of substrata, on the basis of their induction of cell flattening and protuberance formation. In summary, sponge cells were found to modulate their morphology in response to the external environment, expressing features for dynamic activities most fully in the presence of substances close to their natural ECM constituents. These results are discussed in the context of tissue rearrangement as a basic adaptation occurring throughout the life span of these organisms.

Thermodynamic evidence for Ca2+-mediated self-aggregation of Lewis X gold glyconanoparticles. A model for cell adhesion via carbohydrate-carbohydrate interaction.

PubMed

de la Fuente, Jesús M; Eaton, Peter; Barrientos, Africa G; Menéndez, Margarita; Penadés, Soledad

2005-05-04

Thermodynamic evidence for the selective Ca(2+)-mediated self-aggregation via carbohydrate-carbohydrate interactions of gold glyconanoparticles functionalized with the disaccharides lactose (lacto-Au) and maltose (malto-Au), or the biologically relevant trisaccharide Lewis X (Le(X)-Au), was obtained by isothermal titration calorimetry. The aggregation process was also directly visualized by atomic force microscopy. It was shown in the case of the trisaccharide Lewis X that the Ca(2+)-mediated aggregation is a slow process that takes place with a decrease in enthalpy of 160 +/- 30 kcal mol(-)(1), while the heat evolved in the case of lactose and maltose glyconanoparticles was very low and thermal equilibrium was quickly achieved. Measurements in the presence of Mg(2+) and Na(+) cations confirm the selectivity for Ca(2+) of Le(X)-Au glyconanoparticles. The relevance of this result to cell-cell adhesion process mediated by carbohydrate-carbohydrate interactions is discussed.

Proteinaceous determinants of surface colonization in bacteria: bacterial adhesion and biofilm formation from a protein secretion perspective

PubMed Central

Chagnot, Caroline; Zorgani, Mohamed A.; Astruc, Thierry; Desvaux, Mickaël

2013-01-01

Bacterial colonization of biotic or abiotic surfaces results from two quite distinct physiological processes, namely bacterial adhesion and biofilm formation. Broadly speaking, a biofilm is defined as the sessile development of microbial cells. Biofilm formation arises following bacterial adhesion but not all single bacterial cells adhering reversibly or irreversibly engage inexorably into a sessile mode of growth. Among molecular determinants promoting bacterial colonization, surface proteins are the most functionally diverse active components. To be present on the bacterial cell surface, though, a protein must be secreted in the first place. Considering the close association of secreted proteins with their cognate secretion systems, the secretome (which refers both to the secretion systems and their protein substrates) is a key concept to apprehend the protein secretion and related physiological functions. The protein secretion systems are here considered in light of the differences in the cell-envelope architecture between diderm-LPS (archetypal Gram-negative), monoderm (archetypal Gram-positive) and diderm-mycolate (archetypal acid-fast) bacteria. Besides, their cognate secreted proteins engaged in the bacterial colonization process are regarded from single protein to supramolecular protein structure as well as the non-classical protein secretion. This state-of-the-art on the complement of the secretome (the secretion systems and their cognate effectors) involved in the surface colonization process in diderm-LPS and monoderm bacteria paves the way for future research directions in the field. PMID:24133488

Surfactant Functionalization Induces Robust, Differential Adhesion of Tumor Cells and Blood Cells to Charged Nanotube-Coated Biomaterials Under Flow

PubMed Central

Mitchell, Michael J.; Castellanos, Carlos A.; King, Michael R.

2015-01-01

The metastatic spread of cancer cells from the primary tumor to distant sites leads to a poor prognosis in cancers originating from multiple organs. Increasing evidence has linked selectin-based adhesion between circulating tumor cells (CTCs) and endothelial cells of the microvasculature to metastatic dissemination, in a manner similar to leukocyte adhesion during inflammation. Functionalized biomaterial surfaces hold promise as a diagnostic tool to separate CTCs and potentially treat metastasis, utilizing antibody and selectin-mediated interactions for cell capture under flow. However, capture at high purity levels is challenged by the fact that CTCs and leukocytes both possess selectin ligands. Here, a straightforward technique to functionalize and alter the charge of naturally occurring halloysite nanotubes using surfactants is reported to induce robust, differential adhesion of tumor cells and blood cells to nanotube-coated surfaces under flow. Negatively charged sodium dodecanoate-functionalized nanotubes simultaneously enhanced tumor cell capture while negating leukocyte adhesion, both in the presence and absence of adhesion proteins, and can be utilized to isolate circulating tumor cells regardless of biomarker expression. Conversely, diminishing nanotube charge via functionalization with decyltrimethylammonium bromide both abolished tumor cell capture while promoting leukocyte adhesion. PMID:25934290

Improved Osteoblast and Chondrocyte Adhesion and Viability by Surface-Modified Ti6Al4V Alloy with Anodized TiO2 Nanotubes Using a Super-Oxidative Solution

PubMed Central

Beltrán-Partida, Ernesto; Moreno-Ulloa, Aldo; Valdez-Salas, Benjamín; Velasquillo, Cristina; Carrillo, Monica; Escamilla, Alan; Valdez, Ernesto; Villarreal, Francisco

2015-01-01

Titanium (Ti) and its alloys are amongst the most commonly-used biomaterials in orthopedic and dental applications. The Ti-aluminum-vanadium alloy (Ti6Al4V) is widely used as a biomaterial for these applications by virtue of its favorable properties, such as high tensile strength, good biocompatibility and excellent corrosion resistance. TiO2 nanotube (NTs) layers formed by anodization on Ti6Al4V alloy have been shown to improve osteoblast adhesion and function when compared to non-anodized material. In his study, NTs were grown on a Ti6Al4V alloy by anodic oxidation for 5 min using a super-oxidative aqueous solution, and their in vitro biocompatibility was investigated in pig periosteal osteoblasts and cartilage chondrocytes. Scanning electron microscopy (SEM), energy dispersion X-ray analysis (EDX) and atomic force microscopy (AFM) were used to characterize the materials. Cell morphology was analyzed by SEM and AFM. Cell viability was examined by fluorescence microscopy. Cell adhesion was evaluated by nuclei staining and cell number quantification by fluorescence microscopy. The average diameter of the NTs was 80 nm. The results demonstrate improved cell adhesion and viability at Day 1 and Day 3 of cell growth on the nanostructured material as compared to the non-anodized alloy. In conclusion, this study evidences the suitability of NTs grown on Ti6Al4V alloy using a super-oxidative water and a short anodization process to enhance the adhesion and viability of osteoblasts and chondrocytes. The results warrant further investigation for its use as medical implant materials. PMID:28787976

Improved Osteoblast and Chondrocyte Adhesion and Viability by Surface-Modified Ti6Al4V Alloy with Anodized TiO₂ Nanotubes Using a Super-Oxidative Solution.

PubMed

Beltrán-Partida, Ernesto; Moreno-Ulloa, Aldo; Valdez-Salas, Benjamín; Velasquillo, Cristina; Carrillo, Monica; Escamilla, Alan; Valdez, Ernesto; Villarreal, Francisco

2015-03-02

Titanium (Ti) and its alloys are amongst the most commonly-used biomaterials in orthopedic and dental applications. The Ti-aluminum-vanadium alloy (Ti6Al4V) is widely used as a biomaterial for these applications by virtue of its favorable properties, such as high tensile strength, good biocompatibility and excellent corrosion resistance. TiO₂ nanotube (NTs) layers formed by anodization on Ti6Al4V alloy have been shown to improve osteoblast adhesion and function when compared to non-anodized material. In his study, NTs were grown on a Ti6Al4V alloy by anodic oxidation for 5 min using a super-oxidative aqueous solution, and their in vitro biocompatibility was investigated in pig periosteal osteoblasts and cartilage chondrocytes. Scanning electron microscopy (SEM), energy dispersion X-ray analysis (EDX) and atomic force microscopy (AFM) were used to characterize the materials. Cell morphology was analyzed by SEM and AFM. Cell viability was examined by fluorescence microscopy. Cell adhesion was evaluated by nuclei staining and cell number quantification by fluorescence microscopy. The average diameter of the NTs was 80 nm. The results demonstrate improved cell adhesion and viability at Day 1 and Day 3 of cell growth on the nanostructured material as compared to the non-anodized alloy. In conclusion, this study evidences the suitability of NTs grown on Ti6Al4V alloy using a super-oxidative water and a short anodization process to enhance the adhesion and viability of osteoblasts and chondrocytes. The results warrant further investigation for its use as medical implant materials.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Hui; Wei, Yang; Wang, Cheng

The excessive volume changes during cell cycling of Si-based anode in lithium ion batteries impeded its application. One major reason for the cell failure is particle isolation during volume shrinkage in delithiation process, which makes strong adhesion between polymer binder and anode active material particles a highly desirable property. Here, a biomimetic side-chain conductive polymer incorporating catechol, a key adhesive component of the mussel holdfast protein, was synthesized. Atomic force microscopy-based single-molecule force measurements of mussel-inspired conductive polymer binder contacting a silica surface revealed a similar adhesion toward substrate when compared with an effective Si anode binder, homo-poly(acrylic acid), withmore » the added benefit of being electronically conductive. Electrochemical experiments showed a very stable cycling of Si-alloy anodes realized via this biomimetic conducting polymer binder, leading to a high loading Si anode with a good rate performance. We attribute the ability of the Si-based anode to tolerate the volume changes during cycling to the excellent mechanical integrity afforded by the strong interfacial adhesion of the biomimetic conducting polymer.« less

Detection of focal adhesion kinase activation at membrane microdomains by fluorescence resonance energy transfer.

PubMed

Seong, Jihye; Ouyang, Mingxing; Kim, Taejin; Sun, Jie; Wen, Po-Chao; Lu, Shaoying; Zhuo, Yue; Llewellyn, Nicholas M; Schlaepfer, David D; Guan, Jun-Lin; Chien, Shu; Wang, Yingxiao

2011-07-26

Proper subcellular localization of focal adhesion kinase (FAK) is crucial for many cellular processes. It remains, however, unclear how FAK activity is regulated at subcellular compartments. To visualize the FAK activity at different membrane microdomains, we develop a fluorescence resonance energy transfer (FRET)-based FAK biosensor, and target it into or outside of detergent-resistant membrane (DRM) regions at the plasma membrane. Here we show that, on cell adhesion to extracellular matrix proteins or stimulation by platelet-derived growth factor (PDGF), the FRET responses of DRM-targeting FAK biosensor are stronger than that at non-DRM regions, suggesting that FAK activation can occur at DRM microdomains. Further experiments reveal that the PDGF-induced FAK activation is mediated and maintained by Src activity, whereas FAK activation on cell adhesion is independent of, and in fact essential for the Src activation. Therefore, FAK is activated at membrane microdomains with distinct activation mechanisms in response to different physiological stimuli. © 2011 Macmillan Publishers Limited. All rights reserved.

Multiple types of data are required to identify the mechanisms influencing the spatial expansion of melanoma cell colonies.

PubMed

Treloar, Katrina K; Simpson, Matthew J; Haridas, Parvathi; Manton, Kerry J; Leavesley, David I; McElwain, D L Sean; Baker, Ruth E

2013-12-12

The expansion of cell colonies is driven by a delicate balance of several mechanisms including cell motility, cell-to-cell adhesion and cell proliferation. New approaches that can be used to independently identify and quantify the role of each mechanism will help us understand how each mechanism contributes to the expansion process. Standard mathematical modelling approaches to describe such cell colony expansion typically neglect cell-to-cell adhesion, despite the fact that cell-to-cell adhesion is thought to play an important role. We use a combined experimental and mathematical modelling approach to determine the cell diffusivity, D, cell-to-cell adhesion strength, q, and cell proliferation rate, λ, in an expanding colony of MM127 melanoma cells. Using a circular barrier assay, we extract several types of experimental data and use a mathematical model to independently estimate D, q and λ. In our first set of experiments, we suppress cell proliferation and analyse three different types of data to estimate D and q. We find that standard types of data, such as the area enclosed by the leading edge of the expanding colony and more detailed cell density profiles throughout the expanding colony, does not provide sufficient information to uniquely identify D and q. We find that additional data relating to the degree of cell-to-cell clustering is required to provide independent estimates of q, and in turn D. In our second set of experiments, where proliferation is not suppressed, we use data describing temporal changes in cell density to determine the cell proliferation rate. In summary, we find that our experiments are best described using the range D=161-243μm2 hour-1, q=0.3-0.5 (low to moderate strength) and λ=0.0305-0.0398 hour-1, and with these parameters we can accurately predict the temporal variations in the spatial extent and cell density profile throughout the expanding melanoma cell colony. Our systematic approach to identify the cell diffusivity, cell-to-cell adhesion strength and cell proliferation rate highlights the importance of integrating multiple types of data to accurately quantify the factors influencing the spatial expansion of melanoma cell colonies.

Measurement of macrophage adhesion using optical tweezers with backward-scattered detection

NASA Astrophysics Data System (ADS)

Wei, Sung-Yang; Su, Yi-Jr; Shih, Po-Chen; Yang, Shih-Mo; Hsu, Long

2010-08-01

Macrophages are members of the leukocyte family. Tissue damage causes inflammation and release of vasoactive and chemotactic factors, which trigger a local increase in blood flow and capillary permeability. Then, leukocytes accumulate quickly to the infection site. The leukocyte extravasation process takes place according to a sequence of events that involve tethering, activation by a chemoattractant stimulus, adhesion by integrin binding, and migrating to the infection site. The leukocyte extravasation process reveals that adhesion is an important part of the immune system. Optical tweezers have become a useful tool with broad applications in biology and physics. In force measurement, the trapped bead as a probe usually uses a polystyrene bead of 1 μm diameter to measure adhesive force between the trapped beads and cell by optical tweezers. In this paper, using the ray-optics model calculated trapping stiffness and defined the linear displacement ranges. By the theoretical values of stiffness and linear displacement ranges, this study attempted to obtain a proper trapped particle size in measuring adhesive force. Finally, this work investigates real-time adhesion force measurements between human macrophages and trapped beads coated with lipopolysaccharides using optical tweezers with backscattered detection.

Modeling the reversible kinetics of neutrophil aggregation under hydrodynamic shear.

PubMed Central

Neelamegham, S; Taylor, A D; Hellums, J D; Dembo, M; Smith, C W; Simon, S I

1997-01-01

Neutrophil emigration into inflamed tissue is mediated by beta 2-integrin and L-selectin adhesion receptors. Homotypic neutrophil aggregation is also dependent on these molecules, and it provides a model system in which to study adhesion dynamics. In the current study we formulated a mathematical model for cellular aggregation in a linear shear field based on Smoluchowski's two-body collision theory. Neutrophil suspensions activated with chemotactic stimulus and sheared in a cone-plate viscometer rapidly aggregate. Over a range of shear rates (400-800 s-1), approximately 90% of the single cells were recruited into aggregates ranging from doublets to groupings larger than sextuplets. The adhesion efficiency fit to these kinetics reached maximum levels of > 70%. Formed aggregates remained intact and resistant to shear up to 120 s, at which time they spontaneously dissociated back to singlets. The rate of cell disaggregation was linearly proportional to the applied shear rate, and it was approximately 60% lower for doublets as compared to larger aggregates. By accounting for the time-dependent changes in adhesion efficiency, disaggregation rate, and the effects of aggregate geometry, we succeeded in predicting the reversible kinetics of aggregation over a wide range of shear rates and cell concentrations. The combination of viscometry with flow cytometry and mathematical analysis as presented here represents a novel approach to differentiating between the effects of hydrodynamics and the intrinsic biological processes that control cell adhesion. Images FIGURE 3 FIGURE 5 PMID:9083659

Reinjury risk of nano-calcium oxalate monohydrate and calcium oxalate dihydrate crystals on injured renal epithelial cells: aggravation of crystal adhesion and aggregation

PubMed Central

Gan, Qiong-Zhi; Sun, Xin-Yuan; Bhadja, Poonam; Yao, Xiu-Qiong; Ouyang, Jian-Ming

2016-01-01

Background Renal epithelial cell injury facilitates crystal adhesion to cell surface and serves as a key step in renal stone formation. However, the effects of cell injury on the adhesion of nano-calcium oxalate crystals and the nano-crystal-induced reinjury risk of injured cells remain unclear. Methods African green monkey renal epithelial (Vero) cells were injured with H2O2 to establish a cell injury model. Cell viability, superoxide dismutase (SOD) activity, malonaldehyde (MDA) content, propidium iodide staining, hematoxylin–eosin staining, reactive oxygen species production, and mitochondrial membrane potential (Δψm) were determined to examine cell injury during adhesion. Changes in the surface structure of H2O2-injured cells were assessed through atomic force microscopy. The altered expression of hyaluronan during adhesion was examined through laser scanning confocal microscopy. The adhesion of nano-calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD) crystals to Vero cells was observed through scanning electron microscopy. Nano-COM and COD binding was quantitatively determined through inductively coupled plasma emission spectrometry. Results The expression of hyaluronan on the cell surface was increased during wound healing because of Vero cell injury. The structure and function of the cell membrane were also altered by cell injury; thus, nano-crystal adhesion occurred. The ability of nano-COM to adhere to the injured Vero cells was higher than that of nano-COD crystals. The cell viability, SOD activity, and Δψm decreased when nano-crystals attached to the cell surface. By contrast, the MDA content, reactive oxygen species production, and cell death rate increased. Conclusion Cell injury contributes to crystal adhesion to Vero cell surface. The attached nano-COM and COD crystals can aggravate Vero cell injury. As a consequence, crystal adhesion and aggregation are enhanced. These findings provide further insights into kidney stone formation. PMID:27382277

The role of surface carbohydrates on the interaction of microconidia of Trichophyton mentagrophytes with epithelial cells.

PubMed

Esquenazi, Daniele; de Souza, Wanderley; Alviano, Celuta Sales; Rozental, Sonia

2003-03-20

The presence of carbohydrate-binding adhesins on the microconidia of Trichophyton mentagrophytes surface and their role on cellular interactions were investigated. Flow cytometry showed that this fungus recognizes the sugars mannose and galactose. The binding was inhibited by the addition of methyl alpha-D-mannopyranoside and methyl alpha-D-galactopyranoside, and showed higher fluorescence intensity at 37 degrees C than 28 degrees C. Trypsin treatment and heating of the cells reduced the binding, suggesting a (glyco) protein nature of the microconidia adhesin. The interaction of the fungus to Chinese hamster ovary epithelial cells and its glycosylation-deficient mutants demonstrated a higher adhesion index in Lec1 and Lec2 mutants, which express mannose and galactose, respectively, as the terminal carbohydrate on the cell surface. Endocytosed fungi were shown preferentially in Lec2 cells. Addition of the carbohydrates methyl alpha-D-mannopyranoside and methyl alpha-D-galactopyranoside to the interaction medium, pretreatment of Lec1 and Lec2 cells with lectins Concanavalina A and Arachis hypogaea and pretreatment with sodium periodate decreased the adhesion and the endocytic index. Examination of thin section by transmission electron microscopy showed that after fungal ingestion by Lec2 cells the fungi are enclosed in a 'loose'-type vacuole while the other cells are found within a 'tight'-type membrane-bound cytoplasmic vacuole. Our results suggest the occurrence of carbohydrate-specific adhesins on microconidia surface that recognize mannose and galactose. This may have a role in the adhesion process during the infectious process of dermatophytosis.

Integrin traffic - the update.

PubMed

De Franceschi, Nicola; Hamidi, Hellyeh; Alanko, Jonna; Sahgal, Pranshu; Ivaska, Johanna

2015-03-01

Integrins are a family of transmembrane cell surface molecules that constitute the principal adhesion receptors for the extracellular matrix (ECM) and are indispensable for the existence of multicellular organisms. In vertebrates, 24 different integrin heterodimers exist with differing substrate specificity and tissue expression. Integrin-extracellular-ligand interaction provides a physical anchor for the cell and triggers a vast array of intracellular signalling events that determine cell fate. Dynamic remodelling of adhesions, through rapid endocytic and exocytic trafficking of integrin receptors, is an important mechanism employed by cells to regulate integrin-ECM interactions, and thus cellular signalling, during processes such as cell migration, invasion and cytokinesis. The initial concept of integrin traffic as a means to translocate adhesion receptors within the cell has now been expanded with the growing appreciation that traffic is intimately linked to the cell signalling apparatus. Furthermore, endosomal pathways are emerging as crucial regulators of integrin stability and expression in cells. Thus, integrin traffic is relevant in a number of pathological conditions, especially in cancer. Nearly a decade ago we wrote a Commentary in Journal of Cell Science entitled 'Integrin traffic'. With the advances in the field, we felt it would be appropriate to provide the growing number of researchers interested in integrin traffic with an update. © 2015. Published by The Company of Biologists Ltd.

The effect of tunicamycin on the glucose uptake, growth, and cellular adhesion in the protozoan parasite Crithidia fasciculata.

PubMed

Rojas, Robert; Segovia, Christopher; Trombert, Annette Nicole; Santander, Javier; Manque, Patricio

2014-10-01

Crithidia fasciculata represents a very interesting model organism to study biochemical, cellular, and genetic processes unique to members of the family of the Trypanosomatidae. Thus, C. fasciculata parasitizes several species of insects and has been widely used to test new therapeutic strategies against parasitic infections. By using tunicamycin, a potent inhibitor of glycosylation in asparaginyl residues of glycoproteins (N-glycosylation), we demonstrate that N-glycosylation in C. fasciculata cells is involved in modulating glucose uptake, dramatically impacting growth, and cell adhesion. C. fasciculata treated with tunicamycin was severely affected in their ability to replicate and to adhere to polystyrene substrates and losing their ability to aggregate into small and large groups. Moreover, under tunicamycin treatment, the parasites were considerably shorter and rounder and displayed alterations in cytoplasmic vesicles formation. Furthermore, glucose uptake was significantly impaired in a tunicamycin dose-dependent manner; however, no cytotoxic effect was observed. Interestingly, this effect was reversible. Thus, when tunicamycin was removed from the culture media, the parasites recovered its growth rate, cell adhesion properties, and glucose uptake. Collectively, these results suggest that changes in the tunicamycin-dependent glycosylation levels can influence glucose uptake, cell growth, and adhesion in the protozoan parasite C. fasciculata.

Xylella fastidiosa Afimbrial Adhesins Mediate Cell Transmission to Plants by Leafhopper Vectors▿

PubMed Central

Killiny, Nabil; Almeida, Rodrigo P. P.

2009-01-01

The interactions between the economically important plant-pathogenic bacterium Xylella fastidiosa and its leafhopper vectors are poorly characterized. We used different approaches to determine how X. fastidiosa cells interact with the cuticular surface of the foreguts of vectors. We demonstrate that X. fastidiosa binds to different polysaccharides with various affinities and that these interactions are mediated by cell surface carbohydrate-binding proteins. In addition, competition assays showed that N-acetylglucosamine inhibits bacterial adhesion to vector foregut extracts and intact wings, demonstrating that attachment to leafhopper surfaces is affected in the presence of specific polysaccharides. In vitro experiments with several X. fastidiosa knockout mutants indicated that hemagglutinin-like proteins are associated with cell adhesion to polysaccharides. These results were confirmed with biological experiments in which hemagglutinin-like protein mutants were transmitted to plants by vectors at lower rates than that of the wild type. Furthermore, although these mutants were defective in adhesion to the cuticle of vectors, their growth rate once attached to leafhoppers was similar to that of the wild type, suggesting that these proteins are important for initial adhesion of X. fastidiosa to leafhoppers. We propose that X. fastidiosa colonization of leafhopper vectors is a complex, stepwise process similar to the formation of biofilms on surfaces. PMID:19011051

Quantitative characterization of mesenchymal stem cell adhesion to the articular cartilage surface.

PubMed

Hung, Ben P; Babalola, Omotunde M; Bonassar, Lawrence J

2013-12-01

There has been great interest in use of mesenchymal stem cell (MSC)-based therapies for cartilage repair. Most recently, treatments involving intra-articular injection of MSCs have shown great promise for cartilage repair and arthritis therapy, which rely on MSC adhesion to cartilage. While there is some information on chondrocyte adhesion to cartilage, there is relatively little known about the kinetics and strength of MSC adhesion to cartilage. The goals of this study were as follows: (1) to quantify the kinetics and strength of adhesion of marrow-derived MSCs to articular cartilage using standard laboratory hardware; (2) to compare this adhesion behavior to that of articular chondrocytes; and (3) to assess the effect of serial monolayer culture on MSC adhesion. First through fourth passage MSCs and primary articular chondrocytes were allowed to adhere to the articular surface of cartilage disks for up to 30 h and the number of adhered cells was recorded to quantify adhesion kinetics. After 30 h, adherent cells were subjected to centrifugal shear to determine adhesion strength, quantified as the shear necessary to detach half the adhered cells (σ50 ). The number of adhered MSCs and adhesion strength increased with passage number and MSCs adhered more strongly than did primary articular chondrocytes. As such, the kinetics and strength of MSC adhesion to cartilage is not dramatically lower than that for articular chondrocytes. This protocol for assessing cell adhesion to cartilage is simple to implement and may represent an important screening tool for assessing the efficacy of cell-based therapies for cartilage repair. Copyright © 2013 Wiley Periodicals, Inc., a Wiley Company.

In vitro cell culture, platelet adhesion tests and in vivo implant tests of plasma-polymerized para-xylene films

NASA Astrophysics Data System (ADS)

Chou, Chia-Man; Yeh, Chou-Ming; Chung, Chi-Jen; He, Ju-Liang

2013-09-01

Plasma-polymerized para-xylene (PPX) was developed in a previous study by adjusting the process parameters: pulse frequency of the power supply (ωp) and para-xylene monomer flow rate (fp). All the obtained PPX films exhibit an amorphous structure and present hydrophobicity (water contact angle ranging from 98.5° to 121.1°), higher film growth rate and good fibroblast cell proliferation. In this study, in vitro tests (fibroblast cell compatibility and platelet adhesion) and an in vivo animal study were performed by using PPX deposited industrial-grade silicone sheets (IGS) and compared with medical-grade silicone ones (MS), which were commonly manufactured into catheters or drainage tubes in clinical use. The results reveal that PPX deposited at high ωp or high fp, in comparison with MS, exhibit better cell proliferation and clearly shows less cell adhesion regardless of ωp and fp. PPX also exhibit a comparatively lower level of platelet adhesion than MS. In the animal study, PPX-coated IGS result in similar local tissue responses at 3, 7 and 28 days (short-term) and 84 days (long-term) after subcutaneous implantation the abdominal wall of rodents compared with respective responses to MS. These results suggest that PPX-coated industrial-grade silicone is one alternative to high cost medical-grade silicone.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Becker, Ines; Schillig, Cora

A double-sided adhesive metal-based tape for use as contacting aid for SOFC fuel cells is provided. The double-sided metal-based adhesive tape is suitable for simplifying the construction of cell bundles. The double-sided metal-based adhesive tape is used for electrical contacting of the cell connector with the anode and for electrical contacting of the interconnector of the fuel cells with the cell connector. A method for producing the double-sided adhesive metal-base tape is also provided.

In vitro analysis of verapamil-induced immunosuppression: potent inhibition of T cell motility and lymphocytic transmigration through allogeneic endothelial cells.

PubMed

Blaheta, R A; Hailer, N P; Brude, N; Wittig, B; Leckel, K; Oppermann, E; Bachmann, M; Harder, S; Cinatl, J; Scholz, M; Bereiter-Hahn, J; Weber, S; Encke, A; Markus, B H

2000-02-27

Cyclosporine A (CsA) and tacrolimus prevent proliferation but not transendothelial migration of alloreactive lymphocytes into donor organs. As a result, serious adverse effects, such as nephrotoxicity and neurotoxicity, have been observed under CsA/tacrolimus therapy. The incorporation of new drugs with infiltration blocking properties might enhance the efficacy of the current immunosuppressive protocol, allowing lower CsA/tacrolimus dosage. Because Ca2+ plays a critical role in cell-cell interaction, the Ca2+-channel blocker verapamil might be a good cany. didate for supporting CsA/tacrolimus-based therapy. A T-cell endothelial cell coculture model or immobilized immunoglobulin G globulin chimeras were employed to investigate how S- and R- verapamil interfere with the lymphocytic infiltration process. The expression and arrangement of membranous adhesion receptors and cytoskeletal F-actin filaments were analyzed by fluorometric method in the presence of. verapamil. Both verapamil enantiomers strongly inhibited lymphocyte infiltration. CD4+ and CD8+ T-cells were influenced to a similar extent with regard to horizontal locomotion (CD4+=CD8+), but to a different extent with regard to adhesion and penetration (CD4+ > CD8+). Moreover, penetration was blocked to a higher extent than was adhesion. ID50-values were 31 microM (CD4+-adhesion) and 11 microM (CD4+-penetration). Verapamil reduced P-selectin expression on endothelial cells and effectively down-regulated binding of T-cells to immobilized P-selectin immunoglobulin G globulins (ID50=4.4 microM; CD4+). A verapamil-induced reduction of intracellular F-actin in T-lymphocytes was proven to be mainly responsible for diminished cell locomotion. The prevention of CD4+ T-cell penetration by verapamil might argue for its use as an adjunct to CsA/tacrolimus-based immunosuppressive therapy.

Targeted cell adhesion on selectively micropatterned polymer arrays on a poly(dimethylsiloxane) surface.

PubMed

Tang, Linzhi; Min, Junhong; Lee, Eun-Cheol; Kim, Jong Sung; Lee, Nae Yoon

2010-02-01

Herein, we introduce the fabrication of polymer micropattern arrays on a chemically inert poly(dimethylsiloxane) (PDMS) surface and employ them for the selective adhesion of cells. To fabricate the micropattern arrays, a mercapto-ester-based photocurable adhesive was coated onto a mercaptosilane-coated PDMS surface and photopolymerized using a photomask to obtain patterned arrays at the microscale level. Robust polymer patterns, 380 microm in diameter, were successfully fabricated onto a PDMS surface, and cells were selectively targeted toward the patterned regions. Next, the performance of the cell adhesion was observed by anchoring cell adhesive linker, an RGD oligopeptide, on the surface of the mercapto-ester-based adhesive-cured layer. The successful anchoring of the RGD linker was confirmed through various surface characterizations such as water contact angle measurement, XPS analysis, FT-IR analysis, and AFM measurement. The micropatterning of a photocurable adhesive onto a PDMS surface can provide high structural rigidity, a highly-adhesive surface, and a physical pathway for selective cell adhesion, while the incorporated polymer micropattern arrays inside a PDMS microfluidic device can serve as a microfluidic platform for disease diagnoses and high-throughput drug screening.

Cobra CRISP functions as an inflammatory modulator via a novel Zn2+- and heparan sulfate-dependent transcriptional regulation of endothelial cell adhesion molecules.

PubMed

Wang, Yu-Ling; Kuo, Je-Hung; Lee, Shao-Chen; Liu, Jai-Shin; Hsieh, Yin-Cheng; Shih, Yu-Tsung; Chen, Chun-Jung; Chiu, Jeng-Jiann; Wu, Wen-Guey

2010-11-26

Cysteine-rich secretory proteins (CRISPs) have been identified as a toxin family in most animal venoms with biological functions mainly associated with the ion channel activity of cysteine-rich domain (CRD). CRISPs also bind to Zn(2+) at their N-terminal pathogenesis-related (PR-1) domain, but their function remains unknown. Interestingly, similar the Zn(2+)-binding site exists in all CRISP family, including those identified in a wide range of organisms. Here, we report that the CRISP from Naja atra (natrin) could induce expression of vascular endothelial cell adhesion molecules, i.e. intercellular adhesion molecule-1, vascular adhesion molecule-1, and E-selectin, to promote monocytic cell adhesion in a heparan sulfate (HS)- and Zn(2+)-dependent manner. Using specific inhibitors and small interfering RNAs, the activation mechanisms are shown to involve both mitogen-activated protein kinases and nuclear factor-κB. Biophysical characterization of natrin by using fluorescence, circular dichroism, and x-ray crystallographic methods further reveals the presence of two Zn(2+)-binding sites for natrin. The strong binding site is located near the putative Ser-His-Glu catalytic triad of the N-terminal domain. The weak binding site remains to be characterized, but it may modulate HS binding by enhancing its interaction with long chain HS. Our results strongly suggest that natrin may serve as an inflammatory modulator that could perturb the wound-healing process of the bitten victim by regulating adhesion molecule expression in endothelial cells. Our finding uncovers a new aspect of the biological role of CRISP family in immune response and is expected to facilitate future development of new therapeutic strategy for the envenomed victims.

Surface micro- and nano-texturing of stainless steel by femtosecond laser for the control of cell migration.

PubMed

Martínez-Calderon, M; Manso-Silván, M; Rodríguez, A; Gómez-Aranzadi, M; García-Ruiz, J P; Olaizola, S M; Martín-Palma, R J

2016-11-02

The precise control over the interaction between cells and the surface of materials plays a crucial role in optimizing the integration of implanted biomaterials. In this regard, material surface with controlled topographic features at the micro- and nano-scales has been proved to affect the overall cell behavior and therefore the final osseointegration of implants. Within this context, femtosecond (fs) laser micro/nano machining technology was used in this work to modify the surface structure of stainless steel aiming at controlling cell adhesion and migration. The experimental results show that cells tend to attach and preferentially align to the laser-induced nanopatterns oriented in a specific direction. Accordingly, the laser-based fabrication method here described constitutes a simple, clean, and scalable technique which allows a precise control of the surface nano-patterning process and, subsequently, enables the control of cell adhesion, migration, and polarization. Moreover, since our surface-patterning approach does not involve any chemical treatments and is performed in a single step process, it could in principle be applied to most metallic materials.

Surface micro- and nano-texturing of stainless steel by femtosecond laser for the control of cell migration

PubMed Central

Martínez-Calderon, M.; Manso-Silván, M.; Rodríguez, A.; Gómez-Aranzadi, M.; García-Ruiz, J. P.; Olaizola, S. M.; Martín-Palma, R. J.

2016-01-01

The precise control over the interaction between cells and the surface of materials plays a crucial role in optimizing the integration of implanted biomaterials. In this regard, material surface with controlled topographic features at the micro- and nano-scales has been proved to affect the overall cell behavior and therefore the final osseointegration of implants. Within this context, femtosecond (fs) laser micro/nano machining technology was used in this work to modify the surface structure of stainless steel aiming at controlling cell adhesion and migration. The experimental results show that cells tend to attach and preferentially align to the laser-induced nanopatterns oriented in a specific direction. Accordingly, the laser-based fabrication method here described constitutes a simple, clean, and scalable technique which allows a precise control of the surface nano-patterning process and, subsequently, enables the control of cell adhesion, migration, and polarization. Moreover, since our surface-patterning approach does not involve any chemical treatments and is performed in a single step process, it could in principle be applied to most metallic materials. PMID:27805063

Platelet-derived chemokines CXC chemokine ligand (CXCL)7, connective tissue-activating peptide III, and CXCL4 differentially affect and cross-regulate neutrophil adhesion and transendothelial migration.

PubMed

Schenk, Birgit I; Petersen, Frank; Flad, Hans-Dieter; Brandt, Ernst

2002-09-01

In this study, we have examined the major platelet-derived CXC chemokines connective tissue-activating peptide III (CTAP-III), its truncation product neutrophil-activating peptide 2 (CXC chemokine ligand 7 (CXCL7)), as well as the structurally related platelet factor 4 (CXCL4) for their impact on neutrophil adhesion to and transmigration through unstimulated vascular endothelium. Using monolayers of cultured HUVEC, we found all three chemokines to promote neutrophil adhesion, while only CXCL7 induced transmigration. Induction of cell adhesion following exposure to CTAP-III, a molecule to date described to lack neutrophil-stimulating capacity, depended on proteolytical conversion of the inactive chemokine into CXCL7 by neutrophils. This was evident from experiments in which inhibition of the CTAP-III-processing protease and simultaneous blockade of the CXCL7 high affinity receptor CXCR-2 led to complete abrogation of CTAP-III-mediated neutrophil adhesion. CXCL4 at substimulatory dosages modulated CTAP-III- as well as CXCL7-induced adhesion. Although cell adhesion following exposure to CTAP-III was drastically reduced, CXCL7-mediated adhesion underwent significant enhancement. Transendothelial migration of neutrophils in response to CXCL7 or IL-8 (CXCL8) was subject to modulation by CTAP-III, but not CXCL4, as seen by drastic desensitization of the migratory response of neutrophils pre-exposed to CTAP-III, which was paralleled by selective down-modulation of CXCR-2. Altogether our results demonstrate that there exist multiple interactions between platelet-derived chemokines in the regulation of neutrophil adhesion and transendothelial migration.

Perfluorocarbon induces alveolar epithelial cell response through structural and mechanical remodeling.

PubMed

André Dias, Sofia; Planus, Emmanuelle; Angely, Christelle; Lotteau, Luc; Tissier, Renaud; Filoche, Marcel; Louis, Bruno; Pelle, Gabriel; Isabey, Daniel

2018-02-15

During total liquid ventilation, lung cells are exposed to perfluorocarbon (PFC) whose chemophysical properties highly differ from standard aqueous cell feeding medium (DMEM). We herein perform a systematic study of structural and mechanical properties of A549 alveolar epithelial cells in order to characterize their response to PFC exposure, using DMEM as control condition. Changes in F-actin structure, focal adhesion density and glycocalyx distribution are evaluated by confocal fluorescent microscopy. Changes in cell mechanics and adhesion are measured by multiscale magnetic twisting cytometry (MTC). Two different microrheological models (single Voigt and power law) are used to analyze the cell mechanics characterized by cytoskeleton (CSK) stiffness and characteristic relaxation times. Cell-matrix adhesion is analyzed using a stochastic multibond deadhesion model taking into account the non-reversible character of the cell response, allowing us to quantify the adhesion weakness and the number of associated bonds. The roles of F-actin structure and glycocalyx layer are evaluated by depolymerizing F-actin and degrading glycocalyx, respectively. Results show that PFC exposure consistently induces F-actin remodeling, CSK softening and adhesion weakening. These results demonstrate that PFC triggers an alveolar epithelial cell response herein evidenced by a decay in intracellular CSK tension, an adhesion weakening and a glycocalyx layer redistribution. These PFC-induced cell adjustments are consistent with the hypothesis that cells respond to a decrease in adhesion energy at cell surface. This adhesion energy can be even further reduced in the presence of surfactant adsorbed at the cell surface.

Dissecting the roles of ROCK isoforms in stress-induced cell detachment.

PubMed

Shi, Jianjian; Surma, Michelle; Zhang, Lumin; Wei, Lei

2013-05-15

The homologous Rho kinases, ROCK1 and ROCK2, are involved in stress fiber assembly and cell adhesion and are assumed to be functionally redundant. Using mouse embryonic fibroblasts (MEFs) derived from ROCK1(-/-) and ROCK2(-/-) mice, we have recently reported that they play different roles in regulating doxorubicin-induced stress fiber disassembly and cell detachment: ROCK1 is involved in destabilizing the actin cytoskeleton and cell detachment, whereas ROCK2 is required for stabilizing the actin cytoskeleton and cell adhesion. Here, we present additional insights into the roles of ROCK1 and ROCK2 in regulating stress-induced impairment of cell-matrix and cell-cell adhesion. In response to doxorubicin, ROCK1(-/-) MEFs showed significant preservation of both focal adhesions and adherens junctions, while ROCK2(-/-) MEFs exhibited impaired focal adhesions but preserved adherens junctions compared with the wild-type MEFs. Additionally, inhibition of focal adhesion or adherens junction formations by chemical inhibitors abolished the anti-detachment effects of ROCK1 deletion. Finally, ROCK1(-/-) MEFs, but not ROCK2(-/-) MEFs, also exhibited preserved central stress fibers and reduced cell detachment in response to serum starvation. These results add new insights into a novel mechanism underlying the anti-detachment effects of ROCK1 deletion mediated by reduced peripheral actomyosin contraction and increased actin stabilization to promote cell-cell and cell-matrix adhesion. Our studies further support the differential roles of ROCK isoforms in regulating stress-induced loss of central stress fibers and focal adhesions as well as cell detachment.

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.

Glycopolymer functionalization of engineered spider silk protein-based materials for improved cell adhesion.

PubMed

Hardy, John G; Pfaff, André; Leal-Egaña, Aldo; Müller, Axel H E; Scheibel, Thomas R

2014-07-01

Silk protein-based materials are promising biomaterials for application as tissue scaffolds, due to their processability, biocompatibility, and biodegradability. The preparation of films composed of an engineered spider silk protein (eADF4(C16)) and their functionalization with glycopolymers are described. The glycopolymers bind proteins found in the extracellular matrix, providing a biomimetic coating on the films that improves cell adhesion to the surfaces of engineered spider silk films. Such silk-based materials have potential as coatings for degradable implantable devices. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

E-selectin: sialyl Lewis, a dependent adhesion of colon cancer cells, is inhibited differently by antibodies against E-selectin ligands.

PubMed

Srinivas, U; Påhlsson, P; Lundblad, A

1996-09-01

Recent studies have demonstrated that selectins, a new family of cell-adhesion molecules with similar domain structures, mediate the adhesion of peripheral blood cells to interleukin-1 (IL-1)-activated endothelium. In the present study the authors evaluated the role of E-selectin-Sialyl Lewis x (SLe(x))/ Sialyl Lewis a (SLe(a)) interaction in mediating in vitro adhesion of two colon cancer cell lines, HT-29 and COLO 201, to human umbilical cord endothelial cells (HUVEC). Colon cancer cell lines had a strong expression of blood group-related carbohydrate epitopes as evaluated by fluorescence-activated cell sorter (FACS) analysis. It was established that adhesion of HT-29 and COLO 201 cells to IL-1 stimulated HUVEC was calcium dependent and could be inhibited by a monoclonal antibody directed against E-selectin. Prior incubation of cells with two different antibodies directed against SLe(x) and antibodies directed against related Lewis epitopes, Le(x) and Le(a), had no significant effect on adhesion. Three antibodies directed against SLe(a) differed in their capacity to inhibit the adhesion of HT-29 and COLO 201 cells to HUVEC. Only one antibody directed against the SLe(a) structure was effective in inhibiting adhesion of both COLO 201 and HT-29 cells. The difference could not be attributed to titre, the type or number of glycoproteins, or to a difference in the amount of SLe(a) present on individual proteins, suggesting that presence and right presentation of SLe(a) epitope might be important for adhesion of colon cancer cells. Finally, in the in vitro system used, adhesion of HT-29 and COLO 201 cells to activated HUVEC is mediated predominantly by E-selectin/SLe(a) interaction. SLe(x) and related epitopes, Le(x) and Le(a), seem to have limited relevance for colon cancer cell recognition of E-selectin.

Neuron-Glia Adhesion is Inhibited by Antibodies to Neural Determinants

NASA Astrophysics Data System (ADS)

Grumet, M.; Rutishauser, U.; Edelman, G. M.

1983-10-01

Suspensions of embryonic chick neuronal cells adhered to monolayers of glial cells, but few neurons bound to control monolayers of fibroblastic cells from meninges or skin. Neuronal cell-glial cell adhesion was inhibited by prior incubation of the neurons with Fab' fragments of antibodies to neuronal membranes. In contrast, antibodies to the neural cell adhesion molecule (N-CAM) did not inhibit the binding. These results suggest that a specific adhesive mechanism between neurons and glial cells exists and that it is mediated by CAM's that differ from those so far identified.

Epstein-Barr Virus Infection of Polarized Epithelial Cells via the Basolateral Surface by Memory B Cell-Mediated Transfer Infection

PubMed Central

Shannon-Lowe, Claire; Rowe, Martin

2011-01-01

Epstein Barr virus (EBV) exhibits a distinct tropism for both B cells and epithelial cells. The virus persists as a latent infection of memory B cells in healthy individuals, but a role for infection of normal epithelial is also likely. Infection of B cells is initiated by the interaction of the major EBV glycoprotein gp350 with CD21 on the B cell surface. Fusion is triggered by the interaction of the EBV glycoprotein, gp42 with HLA class II, and is thereafter mediated by the core fusion complex, gH/gL/gp42. In contrast, direct infection of CD21-negative epithelial cells is inefficient, but efficient infection can be achieved by a process called transfer infection. In this study, we characterise the molecular interactions involved in the three stages of transfer infection of epithelial cells: (i) CD21-mediated co-capping of EBV and integrins on B cells, and activation of the adhesion molecules, (ii) conjugate formation between EBV-loaded B cells and epithelial cells via the capped adhesion molecules, and (iii) interaction of EBV glycoproteins with epithelial cells, with subsequent fusion and uptake of virions. Infection of epithelial cells required the EBV gH and gL glycoproteins, but not gp42. Using an in vitro model of normal polarized epithelia, we demonstrated that polarization of the EBV receptor(s) and adhesion molecules restricted transfer infection to the basolateral surface. Furthermore, the adhesions between EBV-loaded B cells and the basolateral surface of epithelial cells included CD11b on the B cell interacting with heparan sulphate moieties of CD44v3 and LEEP-CAM on epithelial cells. Consequently, transfer infection was efficiently mediated via CD11b-positive memory B cells but not by CD11b–negative naïve B cells. Together, these findings have important implications for understanding the mechanisms of EBV infection of normal and pre-malignant epithelial cells in vivo. PMID:21573183

Withaferin A inhibits tumor necrosis factor-alpha-induced expression of cell adhesion molecules by inactivation of Akt and NF-kappaB in human pulmonary epithelial cells.

PubMed

Oh, Jung Hwa; Kwon, Taeg Kyu

2009-05-01

We here investigated the functional effect of withaferin A on airway inflammation and its action mechanism. Withaferin A inhibited the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in human lung epithelial A549 cells stimulated with tumor necrosis factor-alpha (TNF-alpha), resulting in the suppression of leukocyte adhesion to lung epithelial A549 cells. In addition, withaferin A inhibited TNF-alpha-induced expression of adhesion molecules (ICAM-1 and VCAM-1) protein and mRNA in a dose-dependent manner. Withaferin A prevented DNA binding activity of nuclear factor-kappaB (NF-kappaB) and nuclear translocation of NF-kappaB. It also inhibited phosphorylation of Akt and extracellular signal-regulated kinase (ERK), which are upstream in the regulation of adhesion molecules by TNF-alpha. Furthermore, withaferin A inhibited U937 monocyte adhesion to A549 cells stimulated by TNF-alpha, suggesting that it may inhibit the binding of these cells by regulating the expression of critical adhesion molecules by TNF-alpha. Taken together, these results suggest that withaferin A inhibits cell adhesion through inhibition of ICAM-1 and VCAM-1 expression, at least in part, by blocking Akt and down-regulating NF-kappaB activity.

Mesenchymal Stem/Multipotent Stromal Cells from Human Decidua Basalis Reduce Endothelial Cell Activation.

PubMed

Alshabibi, Manal A; Al Huqail, Al Joharah; Khatlani, Tanvir; Abomaray, Fawaz M; Alaskar, Ahmed S; Alawad, Abdullah O; Kalionis, Bill; Abumaree, Mohamed Hassan

2017-09-15

Recently, we reported the isolation and characterization of mesenchymal stem cells from the decidua basalis of human placenta (DBMSCs). These cells express a unique combination of molecules involved in many important cellular functions, which make them good candidates for cell-based therapies. The endothelium is a highly specialized, metabolically active interface between blood and the underlying tissues. Inflammatory factors stimulate the endothelium to undergo a change to a proinflammatory and procoagulant state (ie, endothelial cell activation). An initial response to endothelial cell activation is monocyte adhesion. Activation typically involves increased proliferation and enhanced expression of adhesion and inflammatory markers by endothelial cells. Sustained endothelial cell activation leads to a type of damage to the body associated with inflammatory diseases, such as atherosclerosis. In this study, we examined the ability of DBMSCs to protect endothelial cells from activation through monocyte adhesion, by modulating endothelial proliferation, migration, adhesion, and inflammatory marker expression. Endothelial cells were cocultured with DBMSCs, monocytes, monocyte-pretreated with DBMSCs and DBMSC-pretreated with monocytes were also evaluated. Monocyte adhesion to endothelial cells was examined following treatment with DBMSCs. Expression of endothelial cell adhesion and inflammatory markers was also analyzed. The interaction between DBMSCs and monocytes reduced endothelial cell proliferation and monocyte adhesion to endothelial cells. In contrast, endothelial cell migration increased in response to DBMSCs and monocytes. Endothelial cell expression of adhesion and inflammatory molecules was reduced by DBMSCs and DBMSC-pretreated with monocytes. The mechanism of reduced endothelial proliferation involved enhanced phosphorylation of the tumor suppressor protein p53. Our study shows for the first time that DBMSCs protect endothelial cells from activation by inflammation triggered by monocyte adhesion and increased endothelial cell proliferation. These events are manifest in inflammatory diseases, such as atherosclerosis. Therefore, our results suggest that DBMSCs could be usefully employed as a therapeutic strategy for atherosclerosis.

Clustering of adhesion receptors following exposure of insect blood cells to foreign surfaces.

PubMed

Nardi, James B; Zhuang, Shufei; Pilas, Barbara; Bee, Charles Mark; Kanost, Michael R

2005-05-01

Cell-mediated immune responses of insects involve interactions of two main classes of blood cells (hemocytes) known as granular cells and plasmatocytes. In response to a foreign surface, these hemocytes suddenly transform from circulating, non-adherent cells to cells that interact and adhere to each other and the foreign surface. This report presents evidence that during this adhesive transformation the extracellular matrix (ECM) proteins lacunin and a ligand for peanut agglutinin (PNA) lectin are released by granular cells and bind to surfaces of both granular cells and plasmatocytes. ECM protein co-localizes on cell surfaces with the adhesive receptors integrin and neuroglian, a member of the immunoglobulin superfamily. The ECM protein(s) secreted by granular cells are hypothesized to interact with adhesion receptors such as neuroglian and integrin by cross linking and clustering them on hemocyte surfaces. This clustering of receptors is known to enhance the adhesiveness (avidity) of interacting mammalian immune cells. The formation of ring-shaped clusters of these adhesion receptors on surfaces of insect immune cells represents an evolutionary antecedent of the mammalian immunological synapse.

Pea Border Cell Maturation and Release Involve Complex Cell Wall Structural Dynamics.

PubMed

Mravec, Jozef; Guo, Xiaoyuan; Hansen, Aleksander Riise; Schückel, Julia; Kračun, Stjepan Krešimir; Mikkelsen, Maria Dalgaard; Mouille, Grégory; Johansen, Ida Elisabeth; Ulvskov, Peter; Domozych, David S; Willats, William George Tycho

2017-06-01

The adhesion of plant cells is vital for support and protection of the plant body and is maintained by a variety of molecular associations between cell wall components. In some specialized cases, though, plant cells are programmed to detach, and root cap-derived border cells are examples of this. Border cells (in some species known as border-like cells) provide an expendable barrier between roots and the environment. Their maturation and release is an important but poorly characterized cell separation event. To gain a deeper insight into the complex cellular dynamics underlying this process, we undertook a systematic, detailed analysis of pea ( Pisum sativum ) root tip cell walls. Our study included immunocarbohydrate microarray profiling, monosaccharide composition determination, Fourier-transformed infrared microspectroscopy, quantitative reverse transcription-PCR of cell wall biosynthetic genes, analysis of hydrolytic activities, transmission electron microscopy, and immunolocalization of cell wall components. Using this integrated glycobiology approach, we identified multiple novel modes of cell wall structural and compositional rearrangement during root cap growth and the release of border cells. Our findings provide a new level of detail about border cell maturation and enable us to develop a model of the separation process. We propose that loss of adhesion by the dissolution of homogalacturonan in the middle lamellae is augmented by an active biophysical process of cell curvature driven by the polarized distribution of xyloglucan and extensin epitopes. © 2017 American Society of Plant Biologists. All Rights Reserved.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Hyung Gyun; Kim, Ji Young; Hwang, Yong Pil

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 hasmore » 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.« less

PO-12 - The key role of talin-1 in cancer cell extravasation dissected through human vascularized 3D microfluidic model.

PubMed

Gilardi, M; Bersini, S; Calleja, A Boussomier; Kamm, R D; Vanoni, M; Moretti, M

2016-04-01

Metastases are responsible for more than 90% of cancer related mortality. The hematogenous metastatic invasion is a complex process in which the endothelium plays a key role. Extravasation is a dynamic process involving remodeling and change in cell shape and in cytoskeleton whereby a series of strongly dependent interactions between CTCs and endothelium occurs [1]. Talins are proteins regulating focal adhesions and cytoskeleton remodeling. Talin-1 seems to be involved in the aggressiveness, motility, survival and invadopodia formation of cancer cells throughout the entire metastatic cascade [2], being up-regulated in breast cancer cells and mutated in sarcomas. Understand the implication of talin-1 in extravasation could facilitate the design of new therapies and finally fight cancer. We hypothesized that Talin-1 could be specifically involved in extravasation driving each of its steps. We developed a human 3D microfluidic model that enables the study of human cancer cell extravasation within a perfusable human microvascularized organ specific environment[3]. For the study of extravasation we applied microfluidic approach through the development of a microfluidic device in which endothelial cells and fibroblasts generated a 3D human functional vascular networks. Microvessel characterization was performed with immunofluorescence and permeability assays. We knocked-down talin-1 in triple negative breast cancer cell line MDA-MB231 and metastatic fibro-sarcoma cell line HT1080 with SiRNA and verified by Western-blot. Cancer cells were then perfused in the vessels and extravasation monitored through confocal imaging. We developed a human vascularized 3D microfluidic device with human perfusable capillary-like structures embedded in fibrin matrix, characterized by mature endothelium markers and physiological permeability (1.5±0.76)×10(-6) cm/s. We focused on the role of Talin-1 in adhesion to endothelium, trans-endothelial migration (TEM) and early invasion. Adhesion to the endothelium, TEM and migration within the ECM were monitored through confocal analyses. We demonstrated that Talin-1 KD significantly reduced the adhesion efficiency and TEM in both cell lines. Early invasion was also strongly and statistically reduced by the SiRNA treatment in both cell lines. We proved Talin-1 function in driving the extravasation mechanism in a human 3D vascularized environment. We demonstrated that Talin-1 is involved in each part of extravasation significantly affecting adhesion, TEM and the invasion stages. Targeting this protein could thus be an effective strategy to block metastasis. © 2016 Elsevier Ltd. All rights reserved.

Tailoring nanocrystalline diamond coated on titanium for osteoblast adhesion.

PubMed

Pareta, Rajesh; Yang, Lei; Kothari, Abhishek; Sirinrath, Sirivisoot; Xiao, Xingcheng; Sheldon, Brian W; Webster, Thomas J

2010-10-01

Diamond coatings with superior chemical stability, antiwear, and cytocompatibility properties have been considered for lengthening the lifetime of metallic orthopedic implants for over a decade. In this study, an attempt to tailor the surface properties of diamond films on titanium to promote osteoblast (bone forming cell) adhesion was reported. The surface properties investigated here included the size of diamond surface features, topography, wettability, and surface chemistry, all of which were controlled during microwave plasma enhanced chemical-vapor-deposition (MPCVD) processes using CH4-Ar-H2 gas mixtures. The hardness and elastic modulus of the diamond films were also determined. H2 concentration in the plasma was altered to control the crystallinity, grain size, and topography of the diamond coatings, and specific plasma gases (O2 and NH3) were introduced to change the surface chemistry of the diamond coatings. To understand the impact of the altered surface properties on osteoblast responses, cell adhesion tests were performed on the various diamond-coated titanium. The results revealed that nanocrystalline diamond (grain sizes <100 nm) coated titanium dramatically increased surface hardness, and the introduction of O2 and NH3 during the MPCVD process promoted osteoblast adhesion on diamond and, thus, should be further studied for improving orthopedic applications. Copyright 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.

High-content adhesion assay to address limited cell samples†

PubMed Central

Warrick, Jay W.; Young, Edmond W. K.; Schmuck, Eric G.; Saupe, Kurt W.

2013-01-01

Cell adhesion is a broad topic in cell biology that involves physical interactions between cells and other cells or the surrounding extracellular matrix, and is implicated in major research areas including cancer, development, tissue engineering, and regenerative medicine. While current methods have contributed significantly to our understanding of cell adhesion, these methods are unsuitable for tackling many biological questions requiring intermediate numbers of cells (102–105), including small animal biopsies, clinical samples, and rare cell isolates. To overcome this fundamental limitation, we developed a new assay to quantify the adhesion of ~102–103 cells at a time on engineered substrates, and examined the adhesion strength and population heterogeneity via distribution-based modeling. We validated the platform by testing adhesion strength of cancer cells from three different cancer types (breast, prostate, and multiple myeloma) on both IL-1β activated and non-activated endothelial monolayers, and observed significantly increased adhesion for each cancer cell type upon endothelial activation, while identifying and quantifying distinct subpopulations of cell-substrate interactions. We then applied the assay to characterize adhesion of primary bone marrow stromal cells to different cardiac fibroblast-derived matrix substrates to demonstrate the ability to study limited cell populations in the context of cardiac cell-based therapies. Overall, these results demonstrate the sensitivity and robustness of the assay as well as its ability to enable extraction of high content, functional data from limited and potentially rare primary samples. We anticipate this method will enable a new class of biological studies with potential impact in basic and translational research. PMID:23426645

Dissecting the Impact of Matrix Anchorage and Elasticity in Cell Adhesion

PubMed Central

Pompe, Tilo; Glorius, Stefan; Bischoff, Thomas; Uhlmann, Ina; Kaufmann, Martin; Brenner, Sebastian; Werner, Carsten

2009-01-01

Abstract Extracellular matrices determine cellular fate decisions through the regulation of intracellular force and stress. Previous studies suggest that matrix stiffness and ligand anchorage cause distinct signaling effects. We show herein how defined noncovalent anchorage of adhesion ligands to elastic substrates allows for dissection of intracellular adhesion signaling pathways related to matrix stiffness and receptor forces. Quantitative analysis of the mechanical balance in cell adhesion using traction force microscopy revealed distinct scalings of the strain energy imparted by the cells on the substrates dependent either on matrix stiffness or on receptor force. Those scalings suggested the applicability of a linear elastic theoretical framework for the description of cell adhesion in a certain parameter range, which is cell-type-dependent. Besides the deconvolution of biophysical adhesion signaling, site-specific phosphorylation of focal adhesion kinase, dependent either on matrix stiffness or on receptor force, also demonstrated the dissection of biochemical signaling events in our approach. Moreover, the net contractile moment of the adherent cells and their strain energy exerted on the elastic substrate was found to be a robust measure of cell adhesion with a unifying power-law scaling exponent of 1.5 independent of matrix stiffness. PMID:19843448

Controlling the migration behaviors of vascular smooth muscle cells by methoxy poly(ethylene glycol) brushes of different molecular weight and density.

PubMed

Wu, Jindan; Mao, Zhengwei; Gao, Changyou

2012-01-01

Cell migration is an important biological activity. Regulating the migration of vascular smooth muscle cells (VSMCs) is critical in tissue engineering and therapy of cardiovascular disease. In this work, methoxy poly(ethylene glycol) (mPEG) brushes of different molecular weight (Mw 2 kDa, 5 kDa and 10 kDa) and grafting mass (0-859 ng/cm(2)) were prepared on aldehyde-activated glass slides, and were characterized by X-ray photoelectron spectrometer (XPS) and quartz crystal microbalance with dissipation (QCM-d). Adhesion and migration processes of VSMCs were studied as a function of different mPEG Mw and grafting density. We found that these events were mainly regulated by the grafting mass of mPEG regardless of mPEG Mw and grafting density. The VSMCs migrated on the surfaces randomly without a preferential direction. Their migration rates increased initially and then decreased along with the increase of mPEG grafting mass. The fastest rates (~24 μm/h) appeared on the mPEG brushes with grafting mass of 300-500 ng/cm(2) depending on the Mw. Cell adhesion strength, arrangement of cytoskeleton, and gene and protein expression levels of adhesion related proteins were studied to unveil the intrinsic mechanism. It was found that the cell-substrate interaction controlled the cell mobility, and the highest migration rate was achieved on the surfaces with appropriate adhesion force. Copyright © 2011 Elsevier Ltd. All rights reserved.

DEPTOR regulates vascular endothelial cell activation and proinflammatory and angiogenic responses.

PubMed

Bruneau, Sarah; Nakayama, Hironao; Woda, Craig B; Flynn, Evelyn A; Briscoe, David M

2013-09-05

The maintenance of normal tissue homeostasis and the prevention of chronic inflammatory disease are dependent on the active process of inflammation resolution. In endothelial cells (ECs), proinflammation results from the activation of intracellular signaling responses and/or the inhibition of endogenous regulatory/pro-resolution signaling networks that, to date, are poorly defined. In this study, we find that DEP domain containing mTOR interacting protein (DEPTOR) is expressed in different microvascular ECs in vitro and in vivo, and using a small interfering RNA (siRNA) knockdown approach, we find that it regulates mammalian target of rapamycin complex 1 (mTORC1), extracellular signal-regulated kinase 1/2, and signal transducer and activator of transcription 1 activation in part through independent mechanisms. Moreover, using limited gene arrays, we observed that DEPTOR regulates EC activation including mRNA expression of the T-cell chemoattractant chemokines CXCL9, CXCL10, CXCL11, CX3CL1, CCL5, and CCL20 and the adhesion molecules intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 (P < .05). DEPTOR siRNA-transfected ECs also bound increased numbers of peripheral blood mononuclear cells (P < .005) and CD3+ T cells (P < .005) in adhesion assays in vitro and had increased migration and angiogenic responses in spheroid sprouting (P < .01) and wound healing (P < .01) assays. Collectively, these findings define DEPTOR as a critical upstream regulator of EC activation responses and suggest that it plays an important role in endogenous mechanisms of anti-inflammation and pro-resolution.

Synchronized cell attachment triggered by photo-activatable adhesive ligands allows QCM-based detection of early integrin binding

PubMed Central

Iturri, Jagoba; García-Fernández, Luis; Reuning, Ute; García, Andrés J.; Campo, Aránzazu del; Salierno, Marcelo J.

2015-01-01

The Quartz Crystal Microbalance with dissipation (QCM-D) technique was applied to monitor and quantify integrin-RGD recognition during the early stages of cell adhesion. Using QCM-D crystals modified with a photo-activatable RGD peptide, the time point of presentation of adhesive ligand at the surface of the QCM-D crystal could be accurately controlled. This allowed temporal resolution of early integrin-RGD binding and the subsequent cell spreading process, and their separate detection by QCM-D. The specificity of the integrin-RGD binding event was corroborated by performing the experiments in the presence of soluble cyclicRGD as a competitor, and cytochalasin D as inhibitor of cell spreading. Larger frequency change in the QCM-D signal was observed for cells with larger spread area, and for cells overexpressing integrin αvβ3 upon stable transfection. This strategy enables quantification of integrin activity which, in turn, may allow discrimination among different cell types displaying distinct integrin subtypes and expression levels thereof. On the basis of these findings, we believe the strategy can be extended to other photoactivatable ligands to characterize cell membrane receptors activity, a relevant issue for cancer diagnosis (and prognosis) as other several pathologies. PMID:25825012

Do mechanical forces contribute to nanoscale membrane organisation in T cells?

PubMed

Klotzsch, Enrico; Stiegler, Johannes; Ben-Ishay, Eldad; Gaus, Katharina

2015-04-01

Mechanotransduction describes how a cell senses and interacts with its environment. The concept originated in adhesion biology where adhesion receptors, integrins, facilitate force transmission between the extracellular matrix and the intracellular actin cytoskeleton. Indeed, during any adhesive contacts, cells do exert mechanical force. Hence, the probing of the local environment by cells results in mechanical cues that contribute to cellular functions and cell fate decisions such as migration, proliferation, differentiation and apoptosis. On the molecular level, mechanical forces can rearrange proteins laterally within the membrane, regulate their activity by inducing conformational changes and probe the mechanical properties and bond strength of receptor-ligands. From this point of view, it appears surprising that molecular forces have been largely overlooked in membrane organisation and ligand discrimination processes in lymphocytes. During T cell activation, the T cell receptor recognises and distinguishes antigenic from benign endogenous peptides to initiate the reorganisation of membrane proteins into signalling clusters within the immunological synapse. In this review, we asked whether characteristics of fibroblast force sensing could be applied to immune cell antigen recognition and signalling, and outline state-of-the-art experimental strategies for studying forces in the context of membrane organisation. This article is part of a Special Issue entitled: Nanoscale membrane orgainisation and signalling. Copyright © 2014 Elsevier B.V. All rights reserved.

Occludin confers adhesiveness when expressed in fibroblasts.

PubMed

Van Itallie, C M; Anderson, J M

1997-05-01

Occludin is an integral membrane protein specifically associated with tight junctions. Previous studies suggest it is likely to function in forming the intercellular seal. In the present study, we expressed occludin under an inducible promotor in occludin-null fibroblasts to determine whether this protein confers intercellular adhesion. When human occludin is stably expressed in NRK and Rat-1 fibroblasts, which lack endogenous occludin and tight junctions but do have well developed ZO-1-containing adherens-like junctions, occludin colocalizes with ZO-1 to points of cell-cell contact. In contrast, L-cell fibroblasts which lack cadherin-based adherens junctions, target neither ZO-1 nor occludin to sites of cell contact. Occludin-induced adhesion was next quantified using a suspended cell assay. In NRK and Rat-1 cells, occludin expression induces adhesion in the absence of calcium, thus independent of cadherin-cadherin contacts. In contrast, L-cells are nonadhesive in this assay and show no increase in adhesion after induction of occludin expression. Binding of an antibody to the first of the putative extracellular loops of occludin confirmed that this sequence was exposed on the cell surface, and synthetic peptides containing the amino acid sequence of this loop inhibit adhesion induced by occludin expression. These results suggest that the extracellular surface of occludin is directly involved in cell-cell adhesion and the ability to confer adhesiveness correlates with the ability to colocalize with its cytoplasmic binding protein, ZO-1.

Inhibition of cell adhesion by anti–P-selectin aptamer: a new potential therapeutic agent for sickle cell disease

PubMed Central

Gutsaeva, Diana R.; Parkerson, James B.; Yerigenahally, Shobha D.; Kurz, Jeffrey C.; Schaub, Robert G.; Ikuta, Tohru

2011-01-01

Adhesive interactions between circulating sickle red blood cells (RBCs), leukocytes, and endothelial cells are major pathophysiologic events in sickle cell disease (SCD). To develop new therapeutics that efficiently inhibit adhesive interactions, we generated an anti–P-selectin aptamer and examined its effects on cell adhesion using knockout-transgenic SCD model mice. Aptamers, single-stranded oligonucleotides that bind molecular targets with high affinity and specificity, are emerging as new therapeutics for cardiovascular and hematologic disorders. In vitro studies found that the anti–P-selectin aptamer exhibits high specificity to mouse P-selectin but not other selectins. SCD mice were injected with the anti–P-selectin aptamer, and cell adhesion was observed under hypoxia. The anti–P-selectin aptamer inhibited the adhesion of sickle RBCs and leukocytes to endothelial cells by 90% and 80%, respectively. The anti–P-selectin aptamer also increased microvascular flow velocities and reduced the leukocyte rolling flux. SCD mice treated with the anti–P-selectin aptamer demonstrated a reduced mortality rate associated with the experimental procedures compared with control mice. These results demonstrate that anti–P-selectin aptamer efficiently inhibits the adhesion of both sickle RBCs and leukocytes to endothelial cells in SCD model mice, suggesting a critical role for P-selectin in cell adhesion. Anti–P-selectin aptamer may be useful as a novel therapeutic agent for SCD. PMID:20926770

Platelet-independent adhesion of calcium-loaded erythrocytes to von Willebrand factor

PubMed Central

Bierings, Ruben; Meems, Henriet; Mul, Frederik P. J.; Geerts, Dirk; Vlaar, Alexander P. J.; Voorberg, Jan; Hordijk, Peter L.

2017-01-01

Adhesion of erythrocytes to endothelial cells lining the vascular wall can cause vaso-occlusive events that impair blood flow which in turn may result in ischemia and tissue damage. Adhesion of erythrocytes to vascular endothelial cells has been described in multiple hemolytic disorders, especially in sickle cell disease, but the adhesion of normal erythrocytes to endothelial cells has hardly been described. It was shown that calcium-loaded erythrocytes can adhere to endothelial cells. Because sickle erythrocyte adhesion to ECs can be enhanced by ultra-large von Willebrand factor multimers, we investigated whether calcium loading of erythrocytes could promote binding to endothelial cells via ultra-large von Willebrand factor multimers. We used (immunofluorescent) live-cell imaging of washed erythrocytes perfused over primary endothelial cells at venular flow rate. Using this approach, we show that calcium-loaded erythrocytes strongly adhere to histamine-stimulated primary human endothelial cells. This adhesion is mediated by ultra-large von Willebrand factor multimers. Von Willebrand factor knockdown or ADAMTS13 cleavage abolished the binding of erythrocytes to activated endothelial cells under flow. Platelet depletion did not interfere with erythrocyte binding to von Willebrand factor. Our results reveal platelet-independent adhesion of calcium-loaded erythrocytes to endothelium-derived von Willebrand factor. Erythrocyte adhesion to von Willebrand factor may be particularly relevant for venous thrombosis, which is characterized by the formation of erythrocyte-rich thrombi. PMID:28249049

Sintered electrode for solid oxide fuel cells

DOEpatents

Ruka, Roswell J.; Warner, Kathryn A.

1999-01-01

A solid oxide fuel cell fuel electrode is produced by a sintering process. An underlayer is applied to the electrolyte of a solid oxide fuel cell in the form of a slurry, which is then dried. An overlayer is applied to the underlayer and then dried. The dried underlayer and overlayer are then sintered to form a fuel electrode. Both the underlayer and the overlayer comprise a combination of electrode metal such as nickel, and stabilized zirconia such as yttria-stabilized zirconia, with the overlayer comprising a greater percentage of electrode metal. The use of more stabilized zirconia in the underlayer provides good adhesion to the electrolyte of the fuel cell, while the use of more electrode metal in the overlayer provides good electrical conductivity. The sintered fuel electrode is less expensive to produce compared with conventional electrodes made by electrochemical vapor deposition processes. The sintered electrodes exhibit favorable performance characteristics, including good porosity, adhesion, electrical conductivity and freedom from degradation.

Sintered electrode for solid oxide fuel cells

DOEpatents

Ruka, R.J.; Warner, K.A.

1999-06-01

A solid oxide fuel cell fuel electrode is produced by a sintering process. An underlayer is applied to the electrolyte of a solid oxide fuel cell in the form of a slurry, which is then dried. An overlayer is applied to the underlayer and then dried. The dried underlayer and overlayer are then sintered to form a fuel electrode. Both the underlayer and the overlayer comprise a combination of electrode metal such as nickel, and stabilized zirconia such as yttria-stabilized zirconia, with the overlayer comprising a greater percentage of electrode metal. The use of more stabilized zirconia in the underlayer provides good adhesion to the electrolyte of the fuel cell, while the use of more electrode metal in the overlayer provides good electrical conductivity. The sintered fuel electrode is less expensive to produce compared with conventional electrodes made by electrochemical vapor deposition processes. The sintered electrodes exhibit favorable performance characteristics, including good porosity, adhesion, electrical conductivity and freedom from degradation. 4 figs.

Revealing Early Steps of α2β1 Integrin-mediated Adhesion to Collagen Type I by Using Single-Cell Force Spectroscopy

PubMed Central

Taubenberger, Anna; Cisneros, David A.; Friedrichs, Jens; Puech, Pierre-Henri; Muller, Daniel J.

2007-01-01

We have characterized early steps of α2β1 integrin-mediated cell adhesion to a collagen type I matrix by using single-cell force spectroscopy. In agreement with the role of α2β1 as a collagen type I receptor, α2β1-expressing Chinese hamster ovary (CHO)-A2 cells spread rapidly on the matrix, whereas α2β1-negative CHO wild-type cells adhered poorly. Probing CHO-A2 cell detachment forces over a contact time range of 600 s revealed a nonlinear adhesion response. During the first 60 s, cell adhesion increased slowly, and forces associated with the smallest rupture events were consistent with the breakage of individual integrin–collagen bonds. Above 60 s, a fraction of cells rapidly switched into an activated adhesion state marked by up to 10-fold increased detachment forces. Elevated overall cell adhesion coincided with a rise of the smallest rupture forces above the value required to break a single-integrin–collagen bond, suggesting a change from single to cooperative receptor binding. Transition into the activated adhesion mode and the increase of the smallest rupture forces were both blocked by inhibitors of actomyosin contractility. We therefore propose a two-step mechanism for the establishment of α2β1-mediated adhesion as weak initial, single-integrin–mediated binding events are superseded by strong adhesive interactions involving receptor cooperativity and actomyosin contractility. PMID:17314408

Integument pattern formation involves genetic and epigenetic controls: feather arrays simulated by digital hormone models

PubMed Central

Jiang, Ting-Xin; Widelitz, Randall B.; Shen, Wei-Min; Will, Peter; Wu, Da-Yu; Lin, Chih-Min; Jung, Han-Sung; Chuong, Cheng-Ming

2015-01-01

Pattern formation is a fundamental morphogenetic process. Models based on genetic and epigenetic control have been proposed but remain controversial. Here we use feather morphogenesis for further evaluation. Adhesion molecules and/or signaling molecules were first expressed homogenously in feather tracts (restrictive mode, appear earlier) or directly in bud or inter-bud regions (de novo mode, appear later). They either activate or inhibit bud formation, but paradoxically co-localize in the bud. Using feather bud reconstitution, we showed that completely dissociated cells can reform periodic patterns without reference to previous positional codes. The patterning process has the characteristics of being self-organizing, dynamic and plastic. The final pattern is an equilibrium state reached by competition, and the number and size of buds can be altered based on cell number and activator/inhibitor ratio, respectively. We developed a Digital Hormone Model which consists of (1) competent cells without identity that move randomly in a space, (2) extracellular signaling hormones which diffuse by a reaction-diffusion mechanism and activate or inhibit cell adhesion, and (3) cells which respond with topological stochastic actions manifested as changes in cell adhesion. Based on probability, the results are cell clusters arranged in dots or stripes. Thus genetic control provides combinational molecular information which defines the properties of the cells but not the final pattern. Epigenetic control governs interactions among cells and their environment based on physical-chemical rules (such as those described in the Digital Hormone Model). Complex integument patterning is the sum of these two components of control and that is why integument patterns are usually similar but non-identical. These principles may be shared by other pattern formation processes such as barb ridge formation, fingerprints, pigmentation patterning, etc. The Digital Hormone Model can also be applied to swarming robot navigation, reaching intelligent automata and representing a self-re-configurable type of control rather than a follow-the-instruction type of control. PMID:15272377

In vitro cellular adhesion and antimicrobial property of SiO2-MgO-Al2O3-K2O-B2O3-F glass ceramic.

PubMed

Kalmodia, Sushma; Molla, Atiar Rahaman; Basu, Bikramjit

2010-04-01

The aim of the present study was to examine the cellular functionality and antimicrobial properties of SiO(2)-MgO-Al(2)O(3)-K(2)O-B(2)O(3)-F glass ceramics (GC) containing fluorophlogopite as major crystalline phase. The cellular morphology and cell adhesion study using human osteoblast-like Saos-2 cells and mouse fibroblast L929 cells reveals good in vitro cytocompatibility of GC. The potential use of the GC for biomedical application was also assessed by in vitro synthesis of the alkaline phosphatase (ALP) activity of Saos-2 cells. It is proposed that B(2)O(3) actively enhances the cell adhesion and supports osteoconduction process, whereas, fluorine component significantly influences cell viability. The Saos-2 and L929 cells on GC shows extensive multidirectional network of actin cytoskeleton. The in vitro results of this study illustrate how small variation in fluorine and boron in base glass composition influences significantly the biocompatibility and antimicrobial bactericidal property, as evaluated using a range of biochemical assays. Importantly, it shows that the cell viability and osteoconduction can be promoted in glass ceramics with lower fluorine content. The underlying reasons for difference in biological properties are analyzed and reported. It is suggested that oriented crystalline morphology in the lowest fluorine containing glass ceramic enhanced cellular spreading. Overall, the in vitro cell adhesion, cell flattening, cytocompatibility and antimicrobial study of the three different compositions of glass ceramic clearly reveals that microstructure and base glass composition play an important role in enhancing the cellular functionality and antimicrobial property.

Persistent Transmissible Gastroenteritis Virus Infection Enhances Enterotoxigenic Escherichia coli K88 Adhesion by Promoting Epithelial-Mesenchymal Transition in Intestinal Epithelial Cells.

PubMed

Xia, Lu; Dai, Lei; Yu, Qinghua; Yang, Qian

2017-11-01

Transmissible gastroenteritis virus (TGEV) is a coronavirus characterized by diarrhea and high morbidity rates, and the mortality rate is 100% in piglets less than 2 weeks old. Pigs infected with TGEV often suffer secondary infection by other pathogens, which aggravates the severity of diarrhea, but the mechanisms remain unknown. Here, we hypothesized that persistent TGEV infection stimulates the epithelial-mesenchymal transition (EMT), and thus enterotoxigenic Escherichia coli (ETEC) can more easily adhere to generating cells. Intestinal epithelial cells are the primary targets of TGEV and ETEC infections. We found that TGEV can persistently infect porcine intestinal columnar epithelial cells (IPEC-J2) and cause EMT, consistent with multiple changes in key cell characteristics. Infected cells display fibroblast-like shapes; exhibit increases in levels of mesenchymal markers with a corresponding loss of epithelial markers; have enhanced expression levels of interleukin-1β (IL-1β), IL-6, IL-8, transforming growth factor β (TGF-β), and tumor necrosis factor alpha (TNF-α) mRNAs; and demonstrate increases in migratory and invasive behaviors. Additional experiments showed that the activation of the phosphatidylinositol 3-kinase (PI3K)/Akt and extracellular signal-regulated kinase (ERK) signaling pathways via TGF-β is critical for the TGEV-mediated EMT process. Cellular uptake is also modified in cells that have undergone EMT. TGEV-infected cells have higher levels of integrin α5 and fibronectin and exhibit enhanced ETEC K88 adhesion. Reversal of EMT reduces ETEC K88 adhesion and inhibits the expression of integrin α5 and fibronectin. Overall, these results suggest that TGEV infection induces EMT in IPEC-J2 cells, increasing the adhesion of ETEC K88 in the intestine and facilitating dual infection. IMPORTANCE Transmissible gastroenteritis virus (TGEV) causes pig diarrhea and is often followed by secondary infection by other pathogens. In this study, we showed that persistent TGEV infection induces an EMT in porcine intestinal columnar epithelial cells (IPEC-J2) and enhances the adhesion of the secondary pathogen ETEC K88. Additional experiments suggest that integrin α5 and fibronectin play an important role in TGEV-enhanced ETEC K88 adhesion. Reversal of EMT reduces the expression of integrin α5 and fibronectin and also reduces ETEC K88 adhesion. We conclude that TGEV infection triggers EMT and facilitates dual infection. Our results provide new insights into secondary infection and suggest that targeted anti-EMT therapy may have implications for the prevention and treatment of secondary infection. Copyright © 2017 American Society for Microbiology.

Theory and simulations of adhesion receptor dimerization on membrane surfaces.

PubMed

Wu, Yinghao; Honig, Barry; Ben-Shaul, Avinoam

2013-03-19

The equilibrium constants of trans and cis dimerization of membrane bound (2D) and freely moving (3D) adhesion receptors are expressed and compared using elementary statistical-thermodynamics. Both processes are mediated by the binding of extracellular subdomains whose range of motion in the 2D environment is reduced upon dimerization, defining a thin reaction shell where dimer formation and dissociation take place. We show that the ratio between the 2D and 3D equilibrium constants can be expressed as a product of individual factors describing, respectively, the spatial ranges of motions of the adhesive domains, and their rotational freedom within the reaction shell. The results predicted by the theory are compared to those obtained from a novel, to our knowledge, dynamical simulations methodology, whereby pairs of receptors perform realistic translational, internal, and rotational motions in 2D and 3D. We use cadherins as our model system. The theory and simulations explain how the strength of cis and trans interactions of adhesive receptors are affected both by their presence in the constrained intermembrane space and by the 2D environment of membrane surfaces. Our work provides fundamental insights as to the mechanism of lateral clustering of adhesion receptors after cell-cell contact and, more generally, to the formation of lateral microclusters of proteins on cell surfaces. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

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

A Critical Role of Platelet Adhesion in the Initiation of Atherosclerotic Lesion Formation

PubMed Central

Massberg, Steffen; Brand, Korbinian; Grüner, Sabine; Page, Sharon; Müller, Elke; Müller, Iris; Bergmeier, Wolfgang; Richter, Thomas; Lorenz, Michael; Konrad, Ildiko; Nieswandt, Bernhard; Gawaz, Meinrad

2002-01-01

The contribution of platelets to the process of atherosclerosis remains unclear. Here, we show in vivo that platelets adhere to the vascular endothelium of the carotid artery in ApoE − / − mice before the development of manifest atherosclerotic lesions. Platelet–endothelial cell interaction involved both platelet glycoprotein (GP)Ibα and GPIIb-IIIa. Platelet adhesion to the endothelium coincides with inflammatory gene expression and preceded atherosclerotic plaque invasion by leukocytes. Prolonged blockade of platelet adhesion in ApoE − / − mice profoundly reduced leukocyte accumulation in the arterial intima and attenuated atherosclerotic lesion formation in the carotid artery bifurcation, the aortic sinus, and the coronary arteries. These findings establish the platelet as a major player in initiation of the atherogenetic process. PMID:12370251

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: NCC-9-58-162)

[Effect of Golgi α-mannosidase 2 (GM2) gene knockdown on adhesion abilities of human gastric carcinoma cell line BGC-823 and its mechanism].

PubMed

Zeng, Bo; Zeng, Zhen; Liu, Chang; Yang, Yaying

2017-06-01

Objective To investigate the effect of Golgi α-mannosidase II (GM2) gene knockdown on adhesion abilities of BGC-823 human gastric carcinoma cells. Methods Three plasmid vectors expressing GM2 shRNAs and a negative control plasmid vector were designed, constructed and then transfected into BGC-823 cells by Lipofectamine TM 2000. After transfection, the mRNA and protein levels of GM2 in BGC-823 cells were detected by real-time quantitative PCR (qRT-PCR) and Western blotting to evaluate the transfection efficacy. The best plasmid for GM2 gene knockdown was selected and stably transfected into BGC-823 cells. Adhesion abilities of BGC-823 cells after GM2 gene silencing were observed by cell-cell, cell-matrix and cell-endothelial cell adhesion assays. At the same time, the expressions of E-cadherin, P-selectin, CD44v6 and intercellular adhesion molecule-1 (ICAM-1) proteins were detected by Western blotting after GM2 gene knockdown. Results The expression of GM2 was effectively knockdown in GM2-shRNA-2-transfected BGC-823 cells. Compared with the blank control group and the negative control group, the intercellular adhesion ability of the GM2-shRNA-2-transfected cells increased significantly, while their cell-matrix and cell-endothelium adhesion abilities markedly decreased. In GM2-shRNA-2 transfection group, E-cadherin expression was significantly elevated and the P-selectin expression was significantly reduced, while the expression levels of CD44v6 and ICAM-1 were not obviously changed. Conclusion After GM2 gene knockdown, the intercellular adhesion ability of gastric carcinoma BGC-823 cells is enhanced, while the adhesion abilities with the extracellular matrix and endothelial cells are weakened. The changes might be related to the up-regulated expression of E-cadherin and the down-regulation of P-selectin.

Surfactant functionalization induces robust, differential adhesion of tumor cells and blood cells to charged nanotube-coated biomaterials under flow.

PubMed

Mitchell, Michael J; Castellanos, Carlos A; King, Michael R

2015-07-01

The metastatic spread of cancer cells from the primary tumor to distant sites leads to a poor prognosis in cancers originating from multiple organs. Increasing evidence has linked selectin-based adhesion between circulating tumor cells (CTCs) and endothelial cells of the microvasculature to metastatic dissemination, in a manner similar to leukocyte adhesion during inflammation. Functionalized biomaterial surfaces hold promise as a diagnostic tool to separate CTCs and potentially treat metastasis, utilizing antibody and selectin-mediated interactions for cell capture under flow. However, capture at high purity levels is challenged by the fact that CTCs and leukocytes both possess selectin ligands. Here, a straightforward technique to functionalize and alter the charge of naturally occurring halloysite nanotubes using surfactants is reported to induce robust, differential adhesion of tumor cells and blood cells to nanotube-coated surfaces under flow. Negatively charged sodium dodecanoate-functionalized nanotubes simultaneously enhanced tumor cell capture while negating leukocyte adhesion, both in the presence and absence of adhesion proteins, and can be utilized to isolate circulating tumor cells regardless of biomarker expression. Conversely, diminishing nanotube charge via functionalization with decyltrimethylammonium bromide both abolished tumor cell capture while promoting leukocyte adhesion. Copyright © 2015 Elsevier Ltd. All rights reserved.

The CXC-chemokine CXCL4 interacts with integrins implicated in angiogenesis.

PubMed

Aidoudi, Sallouha; Bujakowska, Kinga; Kieffer, Nelly; Bikfalvi, Andreas

2008-07-16

The human CXC-chemokine CXCL4 is a potent inhibitor of tumor-induced angiogenesis. Considering that CXCL4 is sequestered in platelet alpha-granules and released following platelet activation in the vicinity of vessel wall injury, we tested the hypothesis that CXCL4 might function as a ligand for integrins. Integrins are a family of adhesion receptors that play a crucial role in angiogenesis by regulating early angiogenic processes, such as endothelial cell adhesion and migration. Here, we show that CXCL4 interacts with alphavbeta3 on the surface of alphavbeta3-CHO. More importantly, human umbilical vein endothelial cells adhere to immobilized CXCL4 through alphavbeta3 integrin, and also through other integrins, such as alphavbeta5 and alpha5beta1. We further demonstrate that CXCL4-integrin interaction is of functional significance in vitro, since immobilized CXCL4 supported endothelial cell spreading and migration in an integrin-dependent manner. Soluble CXCL4, in turn, inhibits integrin-dependent endothelial cell adhesion and migration. As a whole, our study identifies integrins as novel receptors for CXCL4 that may contribute to its antiangiogenic effect.

The integrin effector PINCH regulates JNK activity and epithelial migration in concert with Ras suppressor 1

PubMed Central

Kadrmas, Julie L.; Smith, Mark A.; Clark, Kathleen A.; Pronovost, Stephen M.; Muster, Nemone; Yates, John R.; Beckerle, Mary C.

2004-01-01

Cell adhesion and migration are dynamic processes requiring the coordinated action of multiple signaling pathways, but the mechanisms underlying signal integration have remained elusive. Drosophila embryonic dorsal closure (DC) requires both integrin function and c-Jun amino-terminal kinase (JNK) signaling for opposed epithelial sheets to migrate, meet, and suture. Here, we show that PINCH, a protein required for integrin-dependent cell adhesion and actin–membrane anchorage, is present at the leading edge of these migrating epithelia and is required for DC. By analysis of native protein complexes, we identify RSU-1, a regulator of Ras signaling in mammalian cells, as a novel PINCH binding partner that contributes to PINCH stability. Mutation of the gene encoding RSU-1 results in wing blistering in Drosophila, demonstrating its role in integrin-dependent cell adhesion. Genetic interaction analyses reveal that both PINCH and RSU-1 antagonize JNK signaling during DC. Our results suggest that PINCH and RSU-1 contribute to the integration of JNK and integrin functions during Drosophila development. PMID:15596544

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...

Evaluation of adhesive penetration of wood fibre by nanoindentation and microscopy

Treesearch

Christopher G. Hunt; Joseph E. Jakes; Warren Grigsby

2010-01-01

Adhesives used in wood products sometimes infiltrate, or diffuse into the solid material of, wood cell walls, potentially modifying their properties. These changes in cell wall properties are likely to impact the performance of adhesive bonds. While adhesive infiltration has been observed by multiple methods, the effect on cell wall properties is not well understood....

Localization of adhesins on the surface of a pathogenic bacterial envelope through atomic force microscopy

NASA Astrophysics Data System (ADS)

Arnal, L.; Longo, G.; Stupar, P.; Castez, M. F.; Cattelan, N.; Salvarezza, R. C.; Yantorno, O. M.; Kasas, S.; Vela, M. E.

2015-10-01

Bacterial adhesion is the first and a significant step in establishing infection. This adhesion normally occurs in the presence of flow of fluids. Therefore, bacterial adhesins must be able to provide high strength interactions with their target surface in order to maintain the adhered bacteria under hydromechanical stressing conditions. In the case of B. pertussis, a Gram-negative bacterium responsible for pertussis, a highly contagious human respiratory tract infection, an important protein participating in the adhesion process is a 220 kDa adhesin named filamentous haemagglutinin (FHA), an outer membrane and also secreted protein that contains recognition domains to adhere to ciliated respiratory epithelial cells and macrophages. In this work, we obtained information on the cell-surface localization and distribution of the B. pertussis adhesin FHA using an antibody-functionalized AFM tip. Through the analysis of specific molecular recognition events we built a map of the spatial distribution of the adhesin which revealed a non-homogeneous pattern. Moreover, our experiments showed a force induced reorganization of the adhesin on the surface of the cells, which could explain a reinforced adhesive response under external forces. This single-molecule information contributes to the understanding of basic molecular mechanisms used by bacterial pathogens to cause infectious disease and to gain insights into the structural features by which adhesins can act as force sensors under mechanical shear conditions.Bacterial adhesion is the first and a significant step in establishing infection. This adhesion normally occurs in the presence of flow of fluids. Therefore, bacterial adhesins must be able to provide high strength interactions with their target surface in order to maintain the adhered bacteria under hydromechanical stressing conditions. In the case of B. pertussis, a Gram-negative bacterium responsible for pertussis, a highly contagious human respiratory tract infection, an important protein participating in the adhesion process is a 220 kDa adhesin named filamentous haemagglutinin (FHA), an outer membrane and also secreted protein that contains recognition domains to adhere to ciliated respiratory epithelial cells and macrophages. In this work, we obtained information on the cell-surface localization and distribution of the B. pertussis adhesin FHA using an antibody-functionalized AFM tip. Through the analysis of specific molecular recognition events we built a map of the spatial distribution of the adhesin which revealed a non-homogeneous pattern. Moreover, our experiments showed a force induced reorganization of the adhesin on the surface of the cells, which could explain a reinforced adhesive response under external forces. This single-molecule information contributes to the understanding of basic molecular mechanisms used by bacterial pathogens to cause infectious disease and to gain insights into the structural features by which adhesins can act as force sensors under mechanical shear conditions. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04644k

Adhesion of Epstein–Barr virus-positive natural killer cell lines to cultured endothelial cells stimulated with inflammatory cytokines

PubMed Central

Kanno, H; Watabe, D; Shimizu, N; Sawai, T

2008-01-01

Chronic active Epstein–Barr virus (EBV) infection (CAEBV) is characterized by chronic recurrent infectious mononucleosis-like symptoms. Approximately one-fourth of CAEBV patients develop vascular lesions with infiltration of EBV-positive lymphoid cells. Furthermore, EBV-positive natural killer (NK)/T cell lymphomas often exhibit angiocentric or angiodestructive lesions. These suggest an affinity of EBV-positive NK/T cells to vascular components. In this study, we evaluated the expression of adhesion molecules and cytokines in EBV-positive NK lymphoma cell lines, SNK1 and SNK6, and examined the role of cytokines in the interaction between NK cell lines and endothelial cells. SNKs expressed intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) at much higher levels than those in EBV-negative T cell lines. SNKs produced the larger amount of tumour necrosis factor (TNF)-α, which caused increased expression of ICAM-1 and VCAM-1 in cultured human endothelial cells, than that from EBV-negative T cell lines. Furthermore, SNKs exhibited increased adhesion to cultured endothelial cells stimulated with TNF-α or interleukin (IL)-1β, and the pretreatment of cytokine-stimulated endothelial cells with anti-VCAM-1-antibodies reduced cell adhesion. These indicate that the up-regulated expression of VCAM-1 on cytokine-stimulated endothelial cells would be important for the adhesion of EBV-positive NK cells and might initiate the vascular lesions. PMID:18190605

Endothelial Activation by Platelets from Sickle Cell Anemia Patients

PubMed Central

Proença-Ferreira, Renata; Brugnerotto, Ana Flávia; Garrido, Vanessa Tonin; Dominical, Venina Marcela; Vital, Daiana Morelli; Ribeiro, Marilene de Fátima Reis; dos Santos, Melissa Ercolin; Traina, Fabíola; Olalla-Saad, Sara T.; Costa, Fernando Ferreira; Conran, Nicola

2014-01-01

Sickle cell anemia (SCA) is associated with a hypercoagulable state. Increased platelet activation is reported in SCA and SCA platelets may present augmented adhesion to the vascular endothelium, potentially contributing to the vaso-occlusive process. We sought to observe the effects of platelets (PLTs) from healthy control (CON) individuals and SCA individuals on endothelial activation, in vitro. Human umbilical vein endothelial cells (HUVEC) were cultured, in the presence, or not, of washed PLTs from CON or steady-state SCA individuals. Supernatants were reserved for cytokine quantification, and endothelial adhesion molecules (EAM) were analyzed by flow cytometry; gene expressions of ICAM1 and genes of the NF-κB pathway were analyzed by qPCR. SCA PLTs were found to be more inflammatory, displaying increased adhesive properties, an increased production of IL-1β and a tendency towards elevated expressions of P-selectin and activated αIIbβ3. Following culture in the presence of SCA PLTs, HUVEC presented significant augmentations in the expressions of the EAM, ICAM-1 and E-selectin, as well as increased IL-8 production and increased ICAM1 and NFKB1 (encodes p50 subunit of NF-κB) gene expressions. Interestingly, transwell inserts abolished the effects of SCA PLTs on EAM expression. Furthermore, an inhibitor of the NF-κB pathway, BAY 11-7082, also prevented the induction of EAM expression on the HUVEC surface by SCA PLTs. In conclusion, we find further evidence to indicate that platelets circulate in an activated state in sickle cell disease and are capable of stimulating endothelial cell activation. This effect appears to be mediated by direct contact, or even adhesion, between the platelets and endothelial cells and via NFκB-dependent signaling. As such, activated platelets in SCD may contribute to endothelial activation and, therefore, to the vaso-occlusive process. Results provide further evidence to support the use of anti-platelet approaches in association with other therapies for SCD. PMID:24551209

Epigallocatechin 3-gallate inhibits 7-ketocholesterol-induced monocyte-endothelial cell adhesion.

PubMed

Yamagata, Kazuo; Tanaka, Noriko; Suzuki, Koichi

2013-07-01

7-Ketocholesterol (7KC) induces monocytic adhesion to endothelial cells, and induces arteriosclerosis while high-density lipoprotein (HDL) inhibits monocytic adhesion to the endothelium. Epigallocatechin 3-gallate (EGCG) was found to have a protective effect against arteriosclerosis. Therefore, the purpose of this study was to examine the possible HDL-like mechanisms of EGCG in endothelial cells by investigating whether EGCG inhibits 7KC-induced monocyte-endothelial cell adhesion by activating HDL-dependent signal transduction pathways. 7KC and/or EGCG were added to human endothelial cells (ISO-HAS), and the adhesion of pro-monocytic U937 cells was examined. The expression of genes associated with HDL effects such as Ca(2+)/calmodulin-dependent kinase II (CaMKKII), liver kinase B (LKD1), PSD-95/Dlg/ZO-1 kinase 1 (PDZK1), phosphatidylinositol 3-kinase (PI3K), intercellular adhesion molecule-1 (ICAM-1), monocyte chemotactic protein-1 (MCP-1), and endothelial nitric oxide synthase (eNOS) was examined by RT-PCR, and ICAM-1 protein expression was evaluated by western blot (WB). Production of reactive oxygen species (ROS) was examined with H2DCFDA. 7KC significantly induced adhesion of U937 cells to human endothelial cells while significantly increasing gene expressions of ICAM-1 and MCP-1 and decreasing eNOS and CaMKKII gene expressions. EGCG inhibited 7KC-induced monocytic adhesion to endothelial cells, and induced expression of eNOS and several genes involved in the CaMKKII pathway. Stimulation of endothelial cells with EGCG produced intracellular ROS, whereas treatment with N-acetylcysteine (NAC) blocked EGCG-induced expression of eNOS and CaMKKII. These results suggest that inhibition of monocyte-endothelial cell adhesion by EGCG is associated with CaMKKII pathway activation by ROS. Inhibition of 7KC-induced monocyte-endothelial cell adhesion induced by EGCG may function similarly to HDL. Copyright © 2013 Elsevier Inc. All rights reserved.

Cell-matrix adhesion characterization using multiple shear stress zones in single stepwise microchannel

NASA Astrophysics Data System (ADS)

Kim, Min-Ji; Doh, Il; Bae, Gab-Yong; Cha, Hyuk-Jin; Cho, Young-Ho

2014-08-01

This paper presents a cell chip capable to characterize cell-matrix adhesion by monitoring cell detachment rate. The proposed cell chip can supply multiple levels of shear stress in single stepwise microchannel. As epithelial-mesenchymal transition (EMT), one of hallmarks of cancer metastasis is closely associated to the interaction with extracelluar matrix (ECM), we took advantage of two lung cancer cell models with different adhesion properties to ECM depending their epithelial or mesenchymal properties, including the pair of lung cancer cells with (A549sh) or without E-cadherin expression (A549sh-Ecad), which would be optimal model to examine the alteration of adhesion properties after EMT induction. The cell-matrix adhesion resisting to shear stress appeared to be remarkably differed between lung cancer cells. The detachment rate of epithelial-like H358 and mesenchymal-like H460 cells was 53%-80% and 25%-66% in the shear stress range of 34-60 dyn/cm2, respectively. A549sh-Ecad cells exhibits lower detachment rate (5%-9%) compared to A549sh cells (14%-40%). By direct comparison of adhesion between A549sh and A549sh-Ecad, we demonstrated that A549shE-cad to mimic EMT were more favorable to the ECM attachment under the various levels of shear stress. The present method can be applied to quantitative analysis of tumor cell-ECM adhesion.

Involvement of lipid rafts in adhesion-induced activation of Met and EGFR.

PubMed

Lu, Ying-Che; Chen, Hong-Chen

2011-10-27

Cell adhesion has been shown to induce activation of certain growth factor receptors in a ligand-independent manner. However, the mechanism for such activation remains obscure. Human epidermal carcinoma A431 cells were used as a model to examine the mechanism for adhesion-induced activation of hepatocyte growth factor receptor Met and epidermal growth factor receptor (EGFR). The cells were suspended and replated on culture dishes under various conditions. The phosphorylation of Met at Y1234/1235 and EGFR at Y1173 were used as indicators for their activation. The distribution of the receptors and lipid rafts on the plasma membrane were visualized by confocal fluorescent microscopy and total internal reflection microscopy. We demonstrate that Met and EGFR are constitutively activated in A431 cells, which confers proliferative and invasive potentials to the cells. The ligand-independent activation of Met and EGFR in A431 cells relies on cell adhesion to a substratum, but is independent of cell spreading, extracellular matrix proteins, and substratum stiffness. This adhesion-induced activation of Met and EGFR cannot be attributed to Src activation, production of reactive oxygen species, and the integrity of the cytoskeleton. In addition, we demonstrate that Met and EGFR are independently activated upon cell adhesion. However, partial depletion of Met and EGFR prevents their activation upon cell adhesion, suggesting that overexpression of the receptors is a prerequisite for their self-activation upon cell adhesion. Although Met and EGFR are largely distributed in 0.04% Triton-insoluble fractions (i.e. raft fraction), their activated forms are detected mainly in 0.04% Triton-soluble fractions (i.e. non-raft fraction). Upon cell adhesion, lipid rafts are accumulated at the cell surface close to the cell-substratum interface, while Met and EGFR are mostly excluded from the membrane enriched by lipid rafts. Our results suggest for the first time that cell adhesion to a substratum may induce a polarized distribution of lipid rafts to the cell-substratum interface, which may allow Met and EGFR to be released from lipid rafts, thus leading to their activation in a ligand-independent manner.

Energy of adhesion of human T cells to adsorption layers of monoclonal antibodies measured by a film trapping technique.

PubMed Central

Ivanov, I B; Hadjiiski, A; Denkov, N D; Gurkov, T D; Kralchevsky, P A; Koyasu, S

1998-01-01

A novel method for studying the interaction of biological cells with interfaces (e.g., adsorption monolayers of antibodies) is developed. The method is called the film trapping technique because the cell is trapped within an aqueous film of equilibrium thickness smaller than the cell diameter. A liquid film of uneven thickness is formed around the trapped cell. When observed in reflected monochromatic light, this film exhibits an interference pattern of concentric bright and dark fringes. From the radii of the fringes one can restore the shape of interfaces and the cell. Furthermore, one can calculate the adhesive energy between the cell membrane and the aqueous film surface (which is covered by a layer of adsorbed proteins and/or specific ligands), as well as the disjoining pressure, representing the force of interaction per unit area of the latter film. The method is applied to two human T cell lines: Jurkat and its T cell receptor negative (TCR-) derivative. The interaction of these cells with monolayers of three different monoclonal antibodies adsorbed at a water-air interface is studied. The results show that the adhesive energy is considerable (above 0.5 mJ/m2) when the adsorption monolayer contains antibodies acting as specific ligands for the receptors expressed on the cell surface. In contrast, the adhesive energy is close to zero in the absence of such a specific ligand-receptor interaction. In principle, the method can be applied to the study of the interaction of a variety of biological cells (B cells, natural killer cells, red blood cells, etc.) with adsorption monolayers of various biologically active molecules. In particular, film trapping provides a tool for the gentle micromanipulation of cells and for monitoring of processes (say the activation of a T lymphocyte) occurring at the single-cell level. PMID:9649417

Structural Analysis of the Synaptic Protein Neuroligin and Its β-Neurexin Complex: Determinants for Folding and Cell Adhesion

PubMed Central

Fabrichny, Igor P.; Leone, Philippe; Sulzenbacher, Gerlind; Comoletti, Davide; Miller, Meghan T.; Taylor, Palmer; Bourne, Yves; Marchot, Pascale

2009-01-01

SUMMARY The neuroligins are postsynaptic cell adhesion proteins whose associations with presynaptic neurexins participate in synaptogenesis. Mutations in the neuroligin and neurexin genes appear to be associated with autism and mental retardation. The crystal structure of a neuroligin reveals features not found in its catalytically active relatives, such as the fully hydrophobic interface forming the functional neuroligin dimer; the conformations of surface loops surrounding the vestigial active center; the location of determinants that are critical for folding and processing; and the absence of a macromolecular dipole and presence of an electronegative, hydrophilic surface for neurexin binding. The structure of a β-neurexin-neuroligin complex reveals the precise orientation of the bound neurexin and, despite a limited resolution, provides substantial information on the Ca2+-dependent interactions network involved in trans-synaptic neurexin-neuroligin association. These structures exemplify how an α/β-hydrolase fold varies in surface topography to confer adhesion properties and provide templates for analyzing abnormal processing or recognition events associated with autism. PMID:18093521

Dietary Selenium Supplementation Modulates Growth of Brain Metastatic Tumors and Changes the Expression of Adhesion Molecules in Brain Microvessels.

PubMed

Wrobel, Jagoda K; Wolff, Gretchen; Xiao, Rijin; Power, Ronan F; Toborek, Michal

2016-08-01

Various dietary agents can modulate tumor invasiveness. The current study explored whether selenoglycoproteins (SeGPs) extracted from selenium-enriched yeast affect tumor cell homing and growth in the brain. Mice were fed diets enriched with specific SeGPs (SeGP40 or SeGP65, 1 mg/kg Se each), glycoproteins (GP40 or GP65, 0.2-0.3 mg/kg Se each) or a control diet (0.2-0.3 mg/kg Se) for 12 weeks. Then, murine Lewis lung carcinoma cells were infused into the brain circulation. Analyses were performed at early (48 h) and late stages (3 weeks) post tumor cell infusion. Imaging of tumor progression in the brain revealed that mice fed SeGP65-enriched diet displayed diminished metastatic tumor growth, fewer extravasating tumor cells and smaller metastatic lesions. While administration of tumor cells resulted in a significant upregulation of adhesion molecules in the early stage of tumor progression, overexpression of VCAM-1 (vascular call adhesion molecule-1) and ALCAM (activated leukocyte cell adhesion molecule) messenger RNA (mRNA) was diminished in SeGP65 supplemented mice. Additionally, mice fed SeGP65 showed decreased expression of acetylated NF-κB p65, 48 h post tumor cell infusion. The results indicate that tumor progression in the brain can be modulated by specific SeGPs. Selenium-containing compounds were more effective than their glycoprotein controls, implicating selenium as a potential negative regulator of metastatic process.

[Biocompatibility of poly-L-lactic acid/Bioglass-guided bone regeneration membranes processed with oxygen plasma].

PubMed

Fang, Wei; Zeng, Shu-Guang; Gao, Wen-Feng

2015-04-01

To prepare and characterize a nano-scale fibrous hydrophilic poly-L-lactic acid/ Bioglass (PLLA/BG) composite membrane and evaluate its biocompatibility as a composite membrane for guiding bone regeneration (GBR). PLLA/BG-guided bone regeneration membrane was treated by oxygen plasma to improved its hydrophilicity. The growth of MG-63 osteoblasts on the membrane was observed using Hoechst fluorescence staining, and the biocompatibility of the membrane was evaluated by calculating the cells adhesion rate and proliferation rate. Osteogenesis of MG-63 cells was assessed by detecting alkaline phosphatase (ALP), and the formation of calcified nodules and cell morphology changes were observed using scanning electron microscope (SEM). The cell adhesion rates of PLLA/BG-guided bone regeneration membrane treated with oxygen plasma were (30.570±0.96)%, (47.27±0.78)%, and (66.78±0.69)% at 1, 3, and 6 h, respectively, significantly higher than those on PLLA membrane and untreated PLLA/BG membrane (P<0.01). The cell proliferation rates on the 3 membranes increased with time, but highest on oxygen plasma-treated PLLA/BG membrane (P<0.01). Hoechst fluorescence staining revealed that oxygen plasma treatment of the PLLA/BG membrane promoted cell adhesion. The membranes with Bioglass promoted the matrix secretion of the osteoblasts. Under SEM, the formation of calcified nodules and spindle-shaped cell morphology were observed on oxygen plasma-treated PLLA/BG membrane. Oxygen plasma-treated PLLA/BG composite membrane has good biocompatibility and can promote adhesion, proliferation and osteogenesis of the osteoblasts.

Clustering T cell GM1 Lipid Rafts Increases Cellular Resistance to Shear on Fibronectin through Changes in Integrin Affinity and Cytoskeletal Dynamics

PubMed Central

Mitchell, Jason S.; Brown, Wells S.; Woodside, Darren G.; Vanderslice, Peter; McIntyre, Bradley W.

2008-01-01

Lipid rafts are small laterally mobile microdomains that are highly enriched in lymphocyte signaling molecules. GM1 gangliosides are a common lipid raft component and have been shown to be important in many T cell functions. The aggregation of specific GM1 lipid rafts can control many T cell activation events, including their novel association with T cell integrins. We found that clustering GM1 lipid rafts can regulate β1 integrin function. This was apparent through increased resistance to shear flow dependent detachment of T cells adherent to the α4β1 and α5β1 integrin ligand fibronectin (FN). Adhesion strengthening as a result of clustering GM1 enriched lipid rafts correlated with increased cellular rigidity and morphology through the localization of cortical F-actin, the resistance to shear induced cell stretching, and an increase in the surface area and symmetry of the contact area between the cell surface and adhesive substrate. Furthermore, clustering GM1 lipid rafts could initiate integrin “inside-out” signaling mechanisms. This was seen through increased integrin-cytoskeleton associations and enhanced soluble binding of FN and VCAM-1 suggesting the induction of high affinity integrin conformations. The activation of these adhesion strengthening characteristics appear to be specific for the aggregation of GM1 lipid rafts as the aggregation of the heterogeneous raft associated molecule CD59 failed to activate these functions. These findings indicate a novel mechanism to signal to β1 integrins and to activate adhesion strengthening processes. PMID:19139760

Platelet adhesion via glycoprotein IIb integrin is critical for atheroprogression and focal cerebral ischemia: an in vivo study in mice lacking glycoprotein IIb.

PubMed

Massberg, Steffen; Schürzinger, Katrin; Lorenz, Michael; Konrad, Ildiko; Schulz, Christian; Plesnila, Nikolaus; Kennerknecht, Elisabeth; Rudelius, Martina; Sauer, Susanne; Braun, Siegmund; Kremmer, Elisabeth; Emambokus, Nikla R; Frampton, Jon; Gawaz, Meinrad

2005-08-23

The platelet glycoprotein (GP) IIb/IIIa integrin binds to fibrinogen and thereby mediates platelet aggregation. Here, we addressed the role of GP IIb for platelet adhesion and determined the relevance of platelet GP IIb for the processes of atherosclerosis and cerebral ischemia-reperfusion (I/R) injury. GP IIb(-/-) mice were generated and bred with ApoE(-/-) animals to create GP IIb(-/-)ApoE(-/-) mice. Platelet adhesion to the mechanically injured or atherosclerotic vessel wall was monitored by in vivo video fluorescence microscopy. In the presence of GP IIb, vascular injury and early atherosclerosis induced platelet adhesion in the carotid artery (CA). In contrast, platelet adhesion was significantly reduced in the absence of GP IIb integrin (P<0.05). To address the contribution of platelet GP IIb to atheroprogression, we determined atherosclerotic lesion formation in the CA and aortic arch (AA) of GP IIb(+/+)ApoE(-/-) or GP IIb(-/-)ApoE(-/-) mice. Interestingly, the absence of GP IIb attenuated lesion formation in CA and AA, indicating that platelets, via GP IIb, contribute substantially to atherosclerosis. Next, we assessed the implication of GP IIb for cerebral I/R injury. We observed that after occlusion of the middle cerebral artery, the cerebral infarct size was drastically reduced in mice lacking GP IIb compared with wild-types. These findings show for the first time in vivo that GP IIb not only mediates platelet aggregation but also triggers platelet adhesion to exposed extracellular matrices and dysfunctional endothelial cells. In a process strictly involving GP IIb, platelets, which are among the first blood cells to arrive at the scene of endothelial dysfunction, contribute essentially to atherosclerosis and cerebral I/R injury.

d(-) Lactic Acid-Induced Adhesion of Bovine Neutrophils onto Endothelial Cells Is Dependent on Neutrophils Extracellular Traps Formation and CD11b Expression.

PubMed

Alarcón, Pablo; Manosalva, Carolina; Conejeros, Ivan; Carretta, María D; Muñoz-Caro, Tamara; Silva, Liliana M R; Taubert, Anja; Hermosilla, Carlos; Hidalgo, María A; Burgos, Rafael A

2017-01-01

Bovine ruminal acidosis is of economic importance as it contributes to reduced milk and meat production. This phenomenon is mainly attributed to an overload of highly fermentable carbohydrate, resulting in increased d(-) lactic acid levels in serum and plasma. Ruminal acidosis correlates with elevated acute phase proteins in blood, along with neutrophil activation and infiltration into various tissues leading to laminitis and aseptic polysynovitis. Previous studies in bovine neutrophils indicated that d(-) lactic acid decreased expression of L-selectin and increased expression of CD11b to concentrations higher than 6 mM, suggesting a potential role in neutrophil adhesion onto endothelia. The two aims of this study were to evaluate whether d(-) lactic acid influenced neutrophil and endothelial adhesion and to trigger neutrophil extracellular trap (NET) production (NETosis) in exposed neutrophils. Exposure of bovine neutrophils to 5 mM d(-) lactic acid elevated NET release compared to unstimulated neutrophil negative controls. Moreover, this NET contains CD11b and histone H 4 citrullinated, the latter was dependent on PAD4 activation, a critical enzyme in DNA decondensation and NETosis. Furthermore, NET formation was dependent on d(-) lactic acid plasma membrane transport through monocarboxylate transporter 1 (MCT1). d(-) lactic acid enhanced neutrophil adhesion onto endothelial sheets as demonstrated by in vitro neutrophil adhesion assays under continuous physiological flow conditions, indicating that cell adhesion was a NET- and a CD11b/ICAM-1-dependent process. Finally, d(-) lactic acid was demonstrated for the first time to trigger NETosis in a PAD4- and MCT1-dependent manner. Thus, d(-) lactic acid-mediated neutrophil activation may contribute to neutrophil-derived pro-inflammatory processes, such as aseptic laminitis and/or polysynovitis in animals suffering acute ruminal acidosis.

Endothelial cell regulation of leukocyte infiltration in inflammatory tissues

PubMed Central

Mantovani, A.; Introna, M.; Dejana, E.

1995-01-01

Endothelial cells play an important, active role in the onset and regulation of inflammatory and immune reactions. Through the production of chemokines they attract leukocytes and activate their adhesive receptors. This leads to the anchorage of leukocytes to the adhesive molecules expressed on the endothelial surface. Leukocyte adhesion to endothelial cells is frequently followed by their extravasation. The mechanisms which regulate the passage of leukocytes through endothelial clefts remain to be clarified. Many indirect data suggest that leukocytes might transfer signals to endothelial cells both through the release of active agents and adhesion to the endothelial cell surface. Adhesive molecules (such as PECAM) on the endothelial cell surface might also ‘direct’ leukocytes through the intercellular junction by haptotaxis. The information available on the molecular structure and functional properties of endothelial chemokines, adhesive molecules or junction organization is still fragmentary. Further work is needed to clarify how they interplay in regulating leukocyte infiltration into tissues. PMID:18475659

Inhibition of sickle red cell adhesion and vasoocclusion in the microcirculation by antioxidants.

PubMed

Kaul, Dhananjay K; Liu, Xiao-du; Zhang, Xiaoqin; Ma, Li; Hsia, Carleton J C; Nagel, Ronald L

2006-07-01

In sickle cell anemia (SCA), inflammatory (i.e., intravascular sickling and transient vasoocclusive) events result in chronic endothelial activation. In addition to sickling behavior, sickle (SS) red blood cells exhibit abnormal interaction with the vascular endothelium, which is considered to have an important role in initiation of vasoocclusion. Upregulation of endothelial adhesion molecules caused by oxidants (and cytokines) may lead to increased SS red cell adhesion. We hypothesize that endothelial activation is indispensable in SS red cell adhesion to the endothelium and that antioxidants will have an inhibitory effect on this interaction. We examined the effect of selected antioxidants in ex vivo mesocecum vasculature, a well-established model that allows measurement of hemodynamic parameters and, by intravital microscopy, can allow quantification of adhesion. We tested antioxidant enzymes (SOD and catalase) and an intravascular SOD mimetic, polynitroxyl albumin (PNA), in the presence of platelet-activating factor (PAF); the latter causes endothelial oxidant generation and endothelial activation, which characterize SCA. In ex vivo preparations, PAF not only induced marked endothelial oxidant generation, it also enhanced SS red cell adhesion, resulting in frequent blockage of small-diameter venules. The adhesion, inversely related to venular diameter, and vasoocclusion were markedly inhibited by antioxidants, resulting in improved hemodynamics. PNA, the most effective antioxidant, also abolished SS red cell adhesion in non-PAF-activated preparations. Thus SS red cell adhesion and related vasoocclusion may be ameliorated by antioxidant therapy with a stable and long-acting molecule (e.g., PNA).

Chemical synthesis, characterisation, and biocompatibility of nanometre scale porous anodic aluminium oxide membranes for use as a cell culture substrate for the vero cell line: a preliminary study.

PubMed

Poinern, Gérrard Eddy Jai; Le, Xuan Thi; O'Dea, Mark; Becker, Thomas; Fawcett, Derek

2014-01-01

In this preliminary study we investigate for the first time the biomedical potential of using porous anodic aluminium oxide (AAO) membranes as a cell substrate for culturing the Cercopithecus aethiops (African green monkey) Kidney (Vero) epithelial cell line. One advantage of using the inorganic AAO membrane is the presence of nanometre scale pore channels that allow the exchange of molecules and nutrients across the membrane. The size of the pore channels can be preselected by adjusting the controlling parameters of a temperature controlled two-step anodization process. The cellular interaction and response of the Vero cell line with an in-house synthesised AAO membrane, a commercially available membrane, and a glass control were assessed by investigating cell adhesion, morphology, and proliferation over a 72 h period. The number of viable cells proliferating over the respective membrane surfaces revealed that the locally produced in-house AAO membrane had cells numbers similar to the glass control. The study revealed evidence of focal adhesion sites over the surface of the nanoporous membranes and the penetration of cellular extensions into the pore structure as well. The outcome of the study has revealed that nanometre scale porous AAO membranes have the potential to become practical cell culture scaffold substrates with the capability to enhance adhesion and proliferation of Vero cells.

Chemical Synthesis, Characterisation, and Biocompatibility of Nanometre Scale Porous Anodic Aluminium Oxide Membranes for Use as a Cell Culture Substrate for the Vero Cell Line: A Preliminary Study

PubMed Central

Poinern, Gérrard Eddy Jai; Le, Xuan Thi; Becker, Thomas; Fawcett, Derek

2014-01-01

In this preliminary study we investigate for the first time the biomedical potential of using porous anodic aluminium oxide (AAO) membranes as a cell substrate for culturing the Cercopithecus aethiops (African green monkey) Kidney (Vero) epithelial cell line. One advantage of using the inorganic AAO membrane is the presence of nanometre scale pore channels that allow the exchange of molecules and nutrients across the membrane. The size of the pore channels can be preselected by adjusting the controlling parameters of a temperature controlled two-step anodization process. The cellular interaction and response of the Vero cell line with an in-house synthesised AAO membrane, a commercially available membrane, and a glass control were assessed by investigating cell adhesion, morphology, and proliferation over a 72 h period. The number of viable cells proliferating over the respective membrane surfaces revealed that the locally produced in-house AAO membrane had cells numbers similar to the glass control. The study revealed evidence of focal adhesion sites over the surface of the nanoporous membranes and the penetration of cellular extensions into the pore structure as well. The outcome of the study has revealed that nanometre scale porous AAO membranes have the potential to become practical cell culture scaffold substrates with the capability to enhance adhesion and proliferation of Vero cells. PMID:24579077

Surface Tension Mediated Under-Water Adhesion of Rigid Spheres on Soft, Charged Surfaces

NASA Astrophysics Data System (ADS)

Sinha, Shayandev; Das, Siddhartha

2015-11-01

Understanding the phenomenon of surface-tension-mediated under-water adhesion is necessary for studying a plethora of physiological and technical phenomena, such as the uptake of bacteria or nanoparticle by cells, attachment of virus on bacterial surfaces, biofouling on large ocean vessels and marine devices, etc. This adhesion phenomenon becomes highly non-trivial in case the soft surface where the adhesion occurs is also charged. Here we propose a theory for analyzing such an under-water adhesion of a rigid sphere on a soft, charged surface, represented by a grafted polyelectrolyte layer (PEL). We develop a model based on the minimization of free energy that, in addition to considering the elastic and the surface-tension-mediated adhesion energies, also accounts for the PEL electric double layer (EDL) induced electrostatic energies. We show that in the presence of surface charges, adhesion gets enhanced. This can be explained by the fact that the increase in the elastic energy is better balanced by the lowering of the EDL energy associated with the adhesion process. The entire behaviour is further dictated by the surface tension components that govern the adhesion energy.

RAFTK, a novel member of the focal adhesion kinase family, is phosphorylated and associates with signaling molecules upon activation of mature T lymphocytes.

PubMed

Ganju, R K; Hatch, W C; Avraham, H; Ona, M A; Druker, B; Avraham, S; Groopman, J E

1997-03-17

The related adhesion focal tyrosine kinase (RAFTK), a recently discovered member of the focal adhesion kinase family, has previously been reported to participate in signal transduction in neuronal cells, megakaryocytes, and B lymphocytes. We have found that RAFTK is constitutively expressed in human T cells and is rapidly phosphorylated upon the activation of the T cell receptor (TCR). This activation also results in an increase in the autophosphorylation and kinase activity of RAFTK. After its stimulation, there was an increase in the association of the src cytoplasmic tyrosine kinase Fyn and the adapter protein Grb2. This association was mediated through the SH2 domains of Fyn and Grb2. RAFTK also co-immunoprecipitates with the SH2 domain of Lck and with the cytoskeletal protein paxillin through its COOH-terminal proline-rich domain. The tyrosine phosphorylation of RAFTK after T cell receptor-mediated stimulation was reduced by the pretreatment of cells with cytochalasin D, suggesting the role of the cytoskeleton in this process. These observations indicate that RAFTK participates in T cell receptor signaling and may act to link signals from the cell surface to the cytoskeleton and thereby affect the host immune response.

Neural cell adhesion molecule mediates initial interactions between spinal cord neurons and muscle cells in culture

PubMed Central

1983-01-01

Previous studies in this laboratory have described a cell surface glycoprotein, called neural cell adhesion molecule or N-CAM, that appears to be a ligand in the adhesion between neural membranes. N-CAM antigenic determinants were also shown to be present on embryonic muscle and an N-CAM-dependent adhesion was demonstrated between retinal cell membranes and muscle cells in short-term assays. The present studies indicate that these antigenic determinants are associated with the N-CAM polypeptide, and that rapid adhesion mediated by this molecule occurs between spinal cord membranes and muscle cells. Detailed examination of the effects of anti-(N-CAM) Fab' fragments in cultures of spinal cord with skeletal muscle showed that the Fab' fragments specifically block adhesion of spinal cord neurites and cells to myotubes. The Fab' did not affect binding of neurites to fibroblasts and collagen substrate, and did not alter myotube morphology. These results indicate that N-CAM adhesion is essential for the in vitro establishment of physical associations between nerve and muscle, and suggest that binding involving N-CAM may be an important early step in synaptogenesis. PMID:6863388

Inhibition of tumor necrosis factor-{alpha}-induced expression of adhesion molecules in human endothelial cells by the saponins derived from roots of Platycodon grandiflorum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Ji Young; Kim, Dong Hee; Kim, Hyung Gyun

2006-01-15

Adhesion molecules play an important role in the development of atherogenesis and are produced by endothelial cells after being stimulated with various inflammatory cytokines. This study examined the effect of saponins that were isolated from the roots of Platycodon grandiflorum A. DC (Campanulaceae), Changkil saponins (CKS), on the cytokine-induced monocyte/human endothelial cell interaction, which is a crucial early event in atherogenesis. CKS significantly inhibited the TNF{alpha}-induced increase in monocyte adhesion to endothelial cells as well as decreased the protein and mRNA expression levels of vascular adhesion molecule-1 and intercellular cell adhesion molecule-1 on endothelial cells. Furthermore, CKS significantly inhibited themore » TNF{alpha}-induced production of intracellular reactive oxygen species (ROS) and activation of NF-{kappa}B by preventing I{kappa}B degradation and inhibiting I{kappa}B kinase activity. Overall, CKS has anti-atherosclerotic and anti-inflammatory activity, which is least in part the result of it reducing the cytokine-induced endothelial adhesion to monocytes by inhibiting intracellular ROS production, NF-{kappa}B activation, and cell adhesion molecule expression in endothelial cells.« less

Corrosion resistance and biological activity of TiO2 implant coatings produced in oxygen-rich environments.

PubMed

Zhang, Rui; Wan, Yi; Ai, Xing; Liu, Zhanqiang; Zhang, Dong

2017-01-01

The physical and chemical properties of bio-titanium alloy implant surfaces play an important role in their corrosion resistance and biological activity. New turning and turning-rolling processes are presented, employing an oxygen-rich environment in order to obtain titanium dioxide layers that can both protect implants from corrosion and also promote cell adhesion. The surface topographies, surface roughnesses and chemical compositions of the sample surfaces were obtained using scanning electron microscopy, a white light interferometer, and the Auger electron spectroscopy, respectively. The corrosion resistance of the samples in a simulated body fluid was determined using electrochemical testing. Biological activity on the samples was also analyzed, using a vitro cell culture system. The results show that compared with titanium oxide layers formed using a turning process in air, the thickness of the titanium oxide layers formed using turning and turning-rolling processes in an oxygen-rich environment increased by 4.6 and 7.3 times, respectively. Using an oxygen-rich atmosphere in the rolling process greatly improves the corrosion resistance of the resulting samples in a simulated body fluid. On samples produced using the turning-rolling process, cells spread quickly and exhibited the best adhesion characteristics.

Adhesion of Salmonella Enteritidis and Listeria monocytogenes on stainless steel welds.

PubMed

Casarin, Letícia Sopeña; Brandelli, Adriano; de Oliveira Casarin, Fabrício; Soave, Paulo Azevedo; Wanke, Cesar Henrique; Tondo, Eduardo Cesar

2014-11-17

Pathogenic microorganisms are able to adhere on equipment surfaces, being possible to contaminate food during processing. Salmonella spp. and Listeria monocytogenes are important pathogens that can be transmitted by food, causing severe foodborne diseases. Most surfaces of food processing industry are made of stainless steel joined by welds. However currently, there are few studies evaluating the influence of welds in the microorganism's adhesion. Therefore the purpose of the present study was to investigate the adhesion of Salmonella Enteritidis and L. monocytogenes on surface of metal inert gas (MIG), and tungsten inert gas (TIG) welding, as well as to evaluate the cell and surface hydrophobicities. Results demonstrated that both bacteria adhered to the surface of welds and stainless steel at same levels. Despite this, bacteria and surfaces demonstrated different levels of hydrophobicity/hydrophilicity, results indicated that there was no correlation between adhesion to welds and stainless steel and the hydrophobicity. Copyright © 2014 Elsevier B.V. All rights reserved.

Wing Defects in Drosophila xenicid Mutant Clones Are Caused by C-Terminal Deletion of Additional Sex Combs (Asx)

PubMed Central

Bischoff, Kara; Ballew, Anna C.; Simon, Michael A.; O'Reilly, Alana M.

2009-01-01

Background The coordinated action of genes that control patterning, cell fate determination, cell size, and cell adhesion is required for proper wing formation in Drosophila. Defects in any of these basic processes can lead to wing aberrations, including blisters. The xenicid mutation was originally identified in a screen designed to uncover regulators of adhesion between wing surfaces [1]. Principal Findings Here, we demonstrate that expression of the βPS integrin or the patterning protein Engrailed are not affected in developing wing imaginal discs in xenicid mutants. Instead, expression of the homeotic protein Ultrabithorax (Ubx) is strongly increased in xenicid mutant cells. Conclusion Our results suggest that upregulation of Ubx transforms cells from a wing blade fate to a haltere fate, and that the presence of haltere cells within the wing blade is the primary defect leading to the adult wing phenotypes observed. PMID:19956620

Axial protocadherin (AXPC) regulates cell fate during notochordal morphogenesis.

PubMed

Yoder, Michael D; Gumbiner, Barry M

2011-11-01

The separation and specification of mesoderm into the notochord and somites involves members of the non-clustered δ-protocadherins. Axial (AXPC) and paraxial (PAPC) protocadherins are expressed in the early dorsal mesoderm and later become refined to the developing notochordal and somitic mesoderm, respectively. The role of PAPC in this process has been studied extensively, but the role of AXPC is poorly understood. Partial knockdown of AXPC causes a specific bent-axis phenotype, while more severe knockdown results in the loss of notochord formation. The inability of these embryos to develop a notochord is not due to a cell-sorting event via changes in cell adhesion during gastrulation, but rather this defect is manifested through the loss of axial mesoderm specification, but not general mesoderm induction. The results presented here show that AXPC functions in notochord morphogenesis by directing cell-fate decisions rather than cell-cell adhesion. Copyright © 2011 Wiley Periodicals, Inc.

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.

Structural Requirements for Outside-In and Inside-Out Signaling by Drosophila Neuroglian, a Member of the L1 Family of Cell Adhesion Molecules

PubMed Central

Hortsch, Michael; Homer, Diahann; Malhotra, Jyoti Dhar; Chang, Sherry; Frankel, Jason; Jefford, Gregory; Dubreuil, Ronald R.

1998-01-01

Expression of the Drosophila cell adhesion molecule neuroglian in S2 cells leads to cell aggregation and the intracellular recruitment of ankyrin to cell contact sites. We localized the region of neuroglian that interacts with ankyrin and investigated the mechanism that limits this interaction to cell contact sites. Yeast two-hybrid analysis and expression of neuroglian deletion constructs in S2 cells identified a conserved 36-amino acid sequence that is required for ankyrin binding. Mutation of a conserved tyrosine residue within this region reduced ankyrin binding and extracellular adhesion. However, residual recruitment of ankyrin by this mutant neuroglian molecule was still limited to cell contacts, indicating that the lack of ankyrin binding at noncontact sites is not caused by tyrosine phosphorylation. A chimeric molecule, in which the extracellular domain of neuroglian was replaced with the corresponding domain from the adhesion molecule fasciclin II, also selectively recruited ankyrin to cell contacts. Thus, outside-in signaling by neuroglian in S2 cells depends on extracellular adhesion, but does not depend on any unique property of its extracellular domain. We propose that the recruitment of ankyrin to cell contact sites depends on a physical rearrangement of neuroglian in response to cell adhesion, and that ankyrin binding plays a reciprocal role in stabilizing the adhesive interaction. PMID:9660878

Structural requirements for outside-in and inside-out signaling by Drosophila neuroglian, a member of the L1 family of cell adhesion molecules.

PubMed

Hortsch, M; Homer, D; Malhotra, J D; Chang, S; Frankel, J; Jefford, G; Dubreuil, R R

1998-07-13

Expression of the Drosophila cell adhesion molecule neuroglian in S2 cells leads to cell aggregation and the intracellular recruitment of ankyrin to cell contact sites. We localized the region of neuroglian that interacts with ankyrin and investigated the mechanism that limits this interaction to cell contact sites. Yeast two-hybrid analysis and expression of neuroglian deletion constructs in S2 cells identified a conserved 36-amino acid sequence that is required for ankyrin binding. Mutation of a conserved tyrosine residue within this region reduced ankyrin binding and extracellular adhesion. However, residual recruitment of ankyrin by this mutant neuroglian molecule was still limited to cell contacts, indicating that the lack of ankyrin binding at noncontact sites is not caused by tyrosine phosphorylation. A chimeric molecule, in which the extracellular domain of neuroglian was replaced with the corresponding domain from the adhesion molecule fasciclin II, also selectively recruited ankyrin to cell contacts. Thus, outside-in signaling by neuroglian in S2 cells depends on extracellular adhesion, but does not depend on any unique property of its extracellular domain. We propose that the recruitment of ankyrin to cell contact sites depends on a physical rearrangement of neuroglian in response to cell adhesion, and that ankyrin binding plays a reciprocal role in stabilizing the adhesive interaction.

Control of the collective migration of enteric neural crest cells by the Complement anaphylatoxin C3a and N-cadherin

PubMed Central

Broders-Bondon, Florence; Paul-Gilloteaux, Perrine; Gazquez, Elodie; Heysch, Julie; Piel, Matthieu; Mayor, Roberto; Lambris, John D.; Dufour, Sylvie

2016-01-01

We analyzed the cellular and molecular mechanisms governing the adhesive and migratory behavior of enteric neural crest cells (ENCCs) during their collective migration within the developing mouse gut. We aimed to decipher the role of the complement anaphylatoxin C3a during this process, because this well-known immune system attractant has been implicated in cephalic NCC co-attraction, a process controlling directional migration. We used the conditional Ht-PA-cre transgenic mouse model allowing a specific ablation of the N-cadherin gene and the expression of a fluorescent reporter in migratory ENCCs without affecting the central nervous system. We performed time-lapse videomicroscopy of ENCCs from control and N-cad-herin mutant gut explants cultured on fibronectin (FN) and micropatterned FN-stripes with C3a or C3aR antagonist, and studied cell migration behavior with the use of triangulation analysis to quantify cell dispersion. We performed ex vivo gut cultures with or without C3aR antagonist to determine the effect on ENCC behavior. Confocal microscopy was used to analyze the cell-matrix adhesion properties. We provide the first demonstration of the localization of the complement anaphylatoxin C3a and its receptor on ENCCs during their migration in the embryonic gut. C3aR receptor inhibition alters ENCC adhesion and migration, perturbing directionality and increasing cell dispersion both in vitro and ex vivo. N-cad-herin-null ENCCs do not respond to C3a co-attraction. These findings indicate that C3a regulates cell migration in a N-cadherin-dependent process. Our results shed light on the role of C3a in regulating collective and directional cell migration, and in ganglia network organization during enteric nervous system ontogenesis. The detection of an immune system chemokine in ENCCs during ENS development may also shed light on new mechanisms for gastrointestinal disorders. PMID:27041467

Molecular mechanisms of mechanotransduction in integrin-mediated cell-matrix adhesion

PubMed Central

Li, Zhenhai; Lee, Hyunjung; Zhu, Cheng

2016-01-01

Cell-matrix adhesion complexes are multi-protein structures linking the extracellular matrix (ECM) to the cytoskeleton. They are essential to both cell motility and function by bidirectionally sensing and transmitting mechanical and biochemical stimulations. Several types of cell-matrix adhesions have been identified and they share many key molecular components, such as integrins and actin-integrin linkers. Mechanochemical coupling between ECM molecules and the actin cytoskeleton has been observed from the single cell to the single molecule level and from immune cells to neuronal cells. However, the mechanisms underlying force regulation of integrin-mediated mechanotransduction still need to be elucidated. In this review article, we focus on integrin-mediated adhesions and discuss force regulation of cell-matrix adhesions and key adaptor molecules, three different force-dependent behaviors, and molecular mechanisms for mechanochemical coupling in force regulation. PMID:27720950

EphA2 promotes cell adhesion and spreading of monocyte and monocyte/macrophage cell lines on integrin ligand-coated surfaces.

PubMed

Saeki, Noritaka; Nishino, Shingo; Shimizu, Tomohiro; Ogawa, Kazushige

2015-01-01

Eph signaling, which arises following stimulation by ephrins, is known to induce opposite cell behaviors such as promoting and inhibiting cell adhesion as well as promoting cell-cell adhesion and repulsion by altering the organization of the actin cytoskeleton and influencing the adhesion activities of integrins. However, crosstalk between Eph/ephrin with integrin signaling has not been fully elucidated in leukocytes, including monocytes and their related cells. Using a cell attachment stripe assay, we have shown that, following stimulation with ephrin-A1, kinase-independent EphA2 promoted cell spreading/elongation as well as adhesion to integrin ligand-coated surfaces in cultured U937 (monocyte) and J774.1 (monocyte/macrophage) cells as well as sublines of these cells expressing dominant negative EphA2 that lacks most of the intracellular region. Moreover, a pull-down assay showed that dominant negative EphA2 is recruited to the β2 integrin/ICAM1 and β2 integrin/VCAM1 molecular complexes in the subline cells following stimulation with ephrin-A1-Fc. Notably, this study is the first comprehensive analysis of the effects of EphA2 receptors on integrin-mediated cell adhesion in monocytic cells. Based on these findings we propose that EphA2 promotes cell adhesion by an unknown signaling pathway that largely depends on the extracellular region of EphA2 and the activation of outside-in integrin signaling.

Biocompatibility enhancement of rare earth magnesium alloy by laser surface processing

NASA Astrophysics Data System (ADS)

Nie, Shilin; Wang, Yuqing; Liu, Haifeng; Guan, Yingchun

2018-01-01

Although magnesium and magnesium alloys are considered biocompatible and biodegradable, insufficient biocompatibility in body fluid environment is still the major drawback of magnesium alloys for their successful applications as biodegradable orthopaedic implants. In this work, magnesium alloy surface with both enhanced corrosion resistance and better cell adhesion property was directly fabricated by laser surface processing. Laser surface melting was used to improve corrosion resistance of Mg-6Gd-0.6Ca alloy. After laser surface melting, laser surface texturing was utilized on melted surface for better cell adhesion property. The corrosion resistance of laser-treated and as-received samples were evaluated using electrochemical technique. The effect of laser surface treatment on phase and microstructure evolution was evaluated using scanning electron microscopy, optical microscopy and X-ray diffraction. This work investigated the effect of laser treatment on cell distribution across the surface of magnesium alloy substrates. Osteoblast was cultured on the laser-treated surface and as-received surface. Cell morphology was observed with a scanning electron microscopy, and cell viability was evaluated by optical density measurement.

Hypergravity Stimulates the Extracellular Matrix/Integrin-Signaling Axis and Proliferation in Primary Osteoblasts

NASA Technical Reports Server (NTRS)

Parra, M.; Vercoutere, W.; Roden, C.; Banerjee, I.; Krauser, W.; Holton, E.; Searby, N.; Globus, R.; Almeida, E.

2003-01-01

We set out to determine the molecular mechanisms involved in the proliferative response of primary rat osteoblasts to mechanical stimulation using cell culture centrifugation as a model for hypergravity. We hypothesized that this proliferative response is mediated by specific integrin/Extracellular Matrix (ECM) interactions. To investigate this question we developed a cell culture centrifuge and an automated system that performs cell fixation during hypergravity loading. We generated expression vectors for various focal adhesion and cytoskeletal proteins fused to GFP or dsRed and visualized these structures in transfected (or infected) osteoblasts. The actin cytoskeleton was also visualized using rhodamine-phalloidin staining and Focal Adhesion Kinase (FAK) levels were assessed biochemically. We observed that a 24 hour exposure to 50-g stimulated proliferation compared to the 1-g control when cells were plated on fibronectin, collagen Type I , and collagen Type IV, but not on uncoated tissue culture plastic surfaces. This proliferative response was greatest for osteoblasts grown on fibronectin (2-fold increase over 1-g control) and collagen Type I (1.4 fold increase over 1-g control), suggesting that specific matrices and integrins are involved in the signaling pathways required for proliferation. Exposing osteoblasts grown on different matrices to 10-g or 25-g showed that effects on proliferation depended on both matrix type and loading level. We found that osteoblasts exposed to a short pulse of hypergravity during adhesion spread further and had more GFP-FAK containing focal adhesions compared to their 1-g controls. While overall levels of FAK did not change, more FAK was in the active (phosphorylated) form under hypergravity than in the 1-g controls. Cytoskeletal F-actin organization into filaments was also more prominent after brief exposures to hypergravity during the first five minutes of adhesion. These results suggest that specific integrins sense hypergravity and activate distinct matrix-dependent FAK signaling pathways that can enhance proliferation. Our results also imply that brief exposures to hypergravity accelerate cell adhesion and spreading processes via the focal adhesion-signaling axis. These results support the role of the ECM/integrin-signaling axis in osteoblast response to hypergravity loading.

The influence of nanostructured features on bacterial adhesion and bone cell functions on severely shot peened 316L stainless steel.

PubMed

Bagherifard, Sara; Hickey, Daniel J; de Luca, Alba C; Malheiro, Vera N; Markaki, Athina E; Guagliano, Mario; Webster, Thomas J

2015-12-01

Substrate grain structure and topography play major roles in mediating cell and bacteria activities. Severe plastic deformation techniques, known as efficient metal-forming and grain refining processes, provide the treated material with novel mechanical properties and can be adopted to modify nanoscale surface characteristics, possibly affecting interactions with the biological environment. This in vitro study evaluates the capability of severe shot peening, based on severe plastic deformation, to modulate the interactions of nanocrystallized metallic biomaterials with cells and bacteria. The treated 316L stainless steel surfaces were first investigated in terms of surface topography, grain size, hardness, wettability and residual stresses. The effects of the induced surface modifications were then separately studied in terms of cell morphology, adhesion and proliferation of primary human osteoblasts (bone forming cells) as well as the adhesion of multiple bacteria strains, specifically Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and ampicillin-resistant Escherichia coli. The results indicated a significant enhancement in surface work hardening and compressive residual stresses, maintenance of osteoblast adhesion and proliferation as well as a remarkable decrease in the adhesion and growth of gram-positive bacteria (S. aureus and S. epidermidis) compared to non-treated and conventionally shot peened samples. Impressively, the decrease in bacteria adhesion and growth was achieved without the use of antibiotics, for which bacteria can develop a resistance towards anyway. By slightly grinding the surface of severe shot peened samples to remove differences in nanoscale surface roughness, the effects of varying substrate grain size were separated from those of varying surface roughness. The expression of vinculin focal adhesions from osteoblasts was found to be singularly and inversely related to grain size, whereas the attachment of gram-positive bacteria (S. aureus and S. epidermidis) decreased with increasing nanoscale surface roughness, and was not affected by grain refinement. Ultimately, this study demonstrated the advantages of the proposed shot peening treatment to produce multifunctional 316L stainless steel materials for improved implant functions without necessitating the use of drugs. Copyright © 2015 Elsevier Ltd. All rights reserved.

Quantifying effects of cyclic stretch on cell-collagen substrate adhesiveness of vascular endothelial cells.

PubMed

Omidvar, Ramin; Tafazzoli-Shadpour, Mohammad; Mahmoodi-Nobar, Farbod; Azadi, Shohreh; Khani, Mohammad-Mehdi

2018-05-01

Vascular endothelium is continuously subjected to mechanical stimulation in the form of shear forces due to blood flow as well as tensile forces as a consequence of blood pressure. Such stimuli influence endothelial behavior and regulate cell-tissue interaction for an optimized functionality. This study aimed to quantify influence of cyclic stretch on the adhesive property and stiffness of endothelial cells. The 10% cyclic stretch with frequency of 1 Hz was applied to a layer of endothelial cells cultured on a polydimethylsiloxane substrate. Cell-substrate adhesion of endothelial cells was examined by the novel approach of atomic force microscope-based single-cell force spectroscopy and cell stiffness was measured by atomic force microscopy. Furthermore, the adhesive molecular bonds were evaluated using modified Hertz contact theory. Our results show that overall adhesion of endothelial cells with substrate decreased after cyclic stretch while they became stiffer. Based on the experimental results and theoretical modeling, the decrease in the number of molecular bonds after cyclic stretch was quantified. In conclusion, in vitro cyclic stretch caused alterations in both adhesive capacity and elastic modulus of endothelial cells through mechanotransductive pathways as two major determinants of the function of these cells within the cardiovascular system.

On the role of extracellular polymeric substances during early stages of Xylella fastidiosa biofilm formation.

PubMed

Lorite, Gabriela S; de Souza, Alessandra A; Neubauer, Daniel; Mizaikoff, Boris; Kranz, Christine; Cotta, Mônica A

2013-02-01

The structural integrity and protection of bacterial biofilms are intrinsically associated with a matrix of extracellular polymeric substances (EPS) produced by the bacteria cells. However, the role of these substances during biofilm adhesion to a surface remains largely unclear. In this study, the influence of EPS on Xylella fastidiosa biofilm formation was investigated. This bacterium is associated with economically important plant diseases; it presents a slow growth rate and thus allows us to pinpoint more precisely the early stages of cell-surface adhesion. Scanning electron microscopy and atomic force microscopy show evidence of EPS production in such early stages and around individual bacteria cells attached to the substrate surface even a few hours after inoculation. In addition, EPS formation was investigated via attenuated total reflectance (ATR) Fourier transform infrared spectroscopy (FTIR). To this end, X. fastidiosa cells were inoculated within an ATR liquid cell assembly. IR-ATR spectra clearly reveal EPS formation already during the early stages of X. fastidiosa biofilm formation, thereby providing supporting evidence for the hypothesis of the relevance of the EPS contribution to the adhesion process. Copyright © 2012 Elsevier B.V. All rights reserved.

Adhesion kinetics of human primary monocytes, dendritic cells, and macrophages: Dynamic cell adhesion measurements with a label-free optical biosensor and their comparison with end-point assays.

PubMed

Orgovan, Norbert; Ungai-Salánki, Rita; Lukácsi, Szilvia; Sándor, Noémi; Bajtay, Zsuzsa; Erdei, Anna; Szabó, Bálint; Horvath, Robert

2016-09-01

Monocytes, dendritic cells (DCs), and macrophages (MFs) are closely related immune cells that differ in their main functions. These specific functions are, to a considerable degree, determined by the differences in the adhesion behavior of the cells. To study the inherently and essentially dynamic aspects of the adhesion of monocytes, DCs, and MFs, dynamic cell adhesion assays were performed with a high-throughput label-free optical biosensor [Epic BenchTop (BT)] on surfaces coated with either fibrinogen (Fgn) or the biomimetic copolymer PLL-g-PEG-RGD. Cell adhesion profiles typically reached their maximum at ∼60 min after cell seeding, which was followed by a monotonic signal decrease, indicating gradually weakening cell adhesion. According to the biosensor response, cell types could be ordered by increasing adherence as monocytes, MFs, and DCs. Notably, all three cell types induced a larger biosensor signal on Fgn than on PLL-g-PEG-RGD. To interpret this result, the molecular layers were characterized by further exploiting the potentials of the biosensor: by measuring the adsorption signal induced during the surface coating procedure, the authors could estimate the surface density of adsorbed molecules and, thus, the number of binding sites potentially presented for the adhesion receptors. Surfaces coated with PLL-g-PEG-RGD presented less RGD sites, but was less efficient in promoting cell spreading than those coated with Fgn; hence, other binding sites in Fgn played a more decisive role in determining cell adherence. To support the cell adhesion data obtained with the biosensor, cell adherence on Fgn-coated surfaces 30-60 min after cell seeding was measured with three complementary techniques, i.e., with (1) a fluorescence-based classical adherence assay, (2) a shear flow chamber applying hydrodynamic shear stress to wash cells away, and (3) an automated micropipette using vacuum-generated fluid flow to lift cells up. These techniques confirmed the results obtained with the high-temporal-resolution Epic BT, but could only provide end-point data. In contrast, complex, nonmonotonic cell adhesion kinetics measured by the high-throughput optical biosensor is expected to open a window on the hidden background of the immune cell-extracellular matrix interactions.

Suppression of endothelial cell adhesion by XJP-1, a new phenolic compound derived from banana peel.

PubMed

Fu, Rong; Yan, Tianhua; Wang, Qiujuan; Guo, Qinglong; Yao, Hequan; Wu, Xiaoming; Li, Yang

2012-01-01

The adhesion of monocytes to activated vascular endothelial cells is a critical event in the initiation of atherosclerosis. Adhesion is mediated by oxidized low-density lipoprotein (ox-LDL) which up-regulates inflammatory markers on endothelial cells. Here we report that (±) 7, 8-dihydroxy-3-methyl-isochromanone-4 (XJP-1), an inhibitor of ox-LDL-induced adhesion of monocytes to endothelial cells blocks cellular functions which are associated with adhesion. We show that XJP-1 down-regulates ox-LDL-induced over-expression of adhesion molecules (ICAM-1 and VCAM-1) in a dose-dependent manner in human umbilical vein endothelial cells (HUVECs), attenuates ox-LDL-induced up-regulation of low-density lipoprotein receptor (LOX)-1, decreases generation of reactive oxygen species (ROS), blocks translocation of nuclear factor-kappa B (NF-κB) activity, and prevents activation of c-Jun N-terminal kinase (JNK)/p38 pathways in endothelial cells. These findings suggest that XJP-1 may attenuate ox-LDL-induced endothelial adhesion of monocytes by blocking expression of adhesion molecules through suppressing ROS/NF-κB, JNK and p38 pathways. Copyright © 2012 Elsevier Inc. All rights reserved.

Isolation of integrin-based adhesion complexes.

PubMed

Jones, Matthew C; Humphries, Jonathan D; Byron, Adam; Millon-Frémillon, Angélique; Robertson, Joseph; Paul, Nikki R; Ng, Daniel H J; Askari, Janet A; Humphries, Martin J

2015-03-02

The integration of cells with their extracellular environment is facilitated by cell surface adhesion receptors, such as integrins, which play important roles in both normal development and the onset of pathologies. Engagement of integrins with their ligands in the extracellular matrix, or counter-receptors on other cells, initiates the intracellular assembly of a wide variety of proteins into adhesion complexes such as focal contacts, focal adhesions, and fibrillar adhesions. The proteins recruited to these complexes mediate bidirectional signaling across the plasma membrane, and, as such, help to coordinate and/or modulate the multitude of physical and chemical signals to which the cell is subjected. The protocols in this unit describe two approaches for the isolation or enrichment of proteins contained within integrin-associated adhesion complexes, together with their local plasma membrane/cytosolic environments, from cells in culture. In the first protocol, integrin-associated adhesion structures are affinity isolated using microbeads coated with extracellular ligands or antibodies. The second protocol describes the isolation of ventral membrane preparations that are enriched for adhesion complex structures. The protocols permit the determination of adhesion complex components via subsequent downstream analysis by western blotting or mass spectrometry. Copyright © 2015 John Wiley & Sons, Inc.

The Synaptic Cell Adhesion Molecule, SynCAM1, Mediates Astrocyte-to-Astrocyte and Astrocyte-to-GnRH Neuron Adhesiveness in the Mouse Hypothalamus

PubMed Central

Sandau, Ursula S.; Mungenast, Alison E.; McCarthy, Jack; Biederer, Thomas; Corfas, Gabriel

2011-01-01

We previously identified synaptic cell adhesion molecule 1 (SynCAM1) as a component of a genetic network involved in the hypothalamic control of female puberty. Although it is well established that SynCAM1 is a synaptic adhesion molecule, its contribution to hypothalamic function is unknown. Here we show that, in addition to the expected neuronal localization illustrated by its presence in GnRH neurons, SynCAM1 is expressed in hypothalamic astrocytes. Cell adhesion assays indicated that SynCAM is recognized by both GnRH neurons and astrocytes as an adhesive partner and promotes cell-cell adhesiveness via homophilic, extracellular domain-mediated interactions. Alternative splicing of the SynCAM1 primary mRNA transcript yields four mRNAs encoding membrane-spanning SynCAM1 isoforms. Variants 1 and 4 are predicted to be both N and O glycosylated. Hypothalamic astrocytes and GnRH-producing GT1-7 cells express mainly isoform 4 mRNA, and sequential N- and O-deglycosylation of proteins extracted from these cells yields progressively smaller SynCAM1 species, indicating that isoform 4 is the predominant SynCAM1 variant expressed in astrocytes and GT1-7 cells. Neither cell type expresses the products of two other SynCAM genes (SynCAM2 and SynCAM3), suggesting that SynCAM-mediated astrocyte-astrocyte and astrocyte-GnRH neuron adhesiveness is mostly mediated by SynCAM1 homophilic interactions. When erbB4 receptor function is disrupted in astrocytes, via transgenic expression of a dominant-negative erbB4 receptor form, SynCAM1-mediated adhesiveness is severely compromised. Conversely, SynCAM1 adhesive behavior is rapidly, but transiently, enhanced in astrocytes by ligand-dependent activation of erbB4 receptors, suggesting that erbB4-mediated events affecting SynCAM1 function contribute to regulate astrocyte adhesive communication. PMID:21486931

Chemical and physical effects on the adhesion, maturation, and survival of monocytes, macrophages, and foreign body giant cells

NASA Astrophysics Data System (ADS)

Collier, Terry Odell, III

Injury caused by biomedical device implantation initiates inflammatory and wound healing responses. Cells migrate to the site of injury to degrade bacteria and toxins, create new vasculature, and form new and repair injured tissue. Blood-proteins rapidly adsorb onto the implanted material surface and express adhesive ligands which mediate cell adhesion on the material surface. Monocyte-derived macrophages and multi-nucleated foreign body giant cells adhere to the surface and degrade the surface of the material. Due to the role of macrophage and foreign body giant cell on material biocompatibility and biostability, the effects of surface chemistry, surface topography and specific proteins on the maturation and survival of monocytes, macrophages and foreign body giant cells has been investigated. Novel molecularly designed materials were used to elucidate the dynamic interactions which occur between inflammatory cells, proteins and surfaces. The effect of protein and protein adhesion was investigated using adhesive protein depleted serum conditions on RGD-modified and silane modified surfaces. The effects of surface chemistry were investigated using temperature responsive surfaces of poly (N-isopropylacrylamide) and micropatterned surfaces of N-(2 aminoethyl)-3-aminopropyltrimethoxysilane regions on an interpenetrating polymer network of polyacrylamide and poly(ethylene glycol). The physical effects were investigated using polyimide scaffold materials and polyurethane materials with surface modifying end groups. The depletion of immunoglobulin G caused decreased levels of macrophage adhesion, foreign body giant cell formation and increased levels of apoptosis. The temporal nature of macrophage adhesion was observed with changing effectiveness of adherent cell detachment with time, which correlated to increased expression of beta1 integrin receptors on detached macrophages with time. The limited ability of the micropatterned surface, polyimide scaffold and surface modified polyurethane materials to control macrophage adhesion indicates the complexity of macrophage adhesion and protein adsorption onto a surface. These studies have indicated components and adhesive mechanisms which can be utilized to create materials with enhanced resistance to macrophage adhesion and/or degradative abilities.

Comparative genome-based identification of a cell wall-anchored protein from Lactobacillus plantarum increases adhesion of Lactococcus lactis to human epithelial cells

PubMed Central

Zhang, Bo; Zuo, Fanglei; Yu, Rui; Zeng, Zhu; Ma, Huiqin; Chen, Shangwu

2015-01-01

Adhesion to host cells is considered important for Lactobacillus plantarum as well as other lactic acid bacteria (LAB) to persist in human gut and thus exert probiotic effects. Here, we sequenced the genome of Lt. plantarum strain NL42 originating from a traditional Chinese dairy product, performed comparative genomic analysis and characterized a novel adhesion factor. The genome of NL42 was highly divergent from its closest neighbors, especially in six large genomic regions. NL42 harbors a total of 42 genes encoding adhesion-associated proteins; among them, cwaA encodes a protein containing multiple domains, including five cell wall surface anchor repeat domains and an LPxTG-like cell wall anchor motif. Expression of cwaA in Lactococcus lactis significantly increased its autoaggregation and hydrophobicity, and conferred the new ability to adhere to human colonic epithelial HT-29 cells by targeting cellular surface proteins, and not carbohydrate moieties, for CwaA adhesion. In addition, the recombinant Lc. lactis inhibited adhesion of Staphylococcus aureus and Escherichia coli to HT-29 cells, mainly by exclusion. We conclude that CwaA is a novel adhesion factor in Lt. plantarum and a potential candidate for improving the adhesion ability of probiotics or other bacteria of interest. PMID:26370773

Patterning N-type and S-type Neuroblastoma Cells with Pluronic F108 and ECM Proteins

PubMed Central

Corey, Joseph M.; Gertz, Caitlyn C.; Sutton, Thomas J.; Chen, Qiaoran; Mycek, Katherine B.; Wang, Bor-Shuen; Martin, Abbey A.; Johnson, Sara L.; Feldman, Eva L.

2009-01-01

Influencing cell shape using micropatterned substrates affects cell behaviors, such as proliferation and apoptosis. Cell shape may also affect these behaviors in human neuroblastoma (NBL) cancer, but to date, no substrate design has effectively patterned multiple clinically important human NBL lines. In this study, we investigated whether Pluronic F108 was an effective anti-adhesive coating for human NBL cells and whether it would localize three NBL lines to adhesive regions of tissue culture plastic or collagen I on substrate patterns. The adhesion and patterning of an S-type line, SH-EP, and two N-type lines, SH-SY5Y and IMR-32, were tested. In adhesion assays, F108 deterred NBL adhesion equally as well as two anti-adhesive organofunctional silanes and far better than bovine serum albumin. Patterned stripes of F108 restricted all three human NBL lines to adhesive stripes of tissue culture plastic. We then investigated four schemes of applying collagen and F108 to different regions of a substrate. Contact with collagen obliterates the ability of F108 to deter NBL adhesion, limiting how both materials can be applied to substrates to produce high fidelity NBL patterning. This patterned substrate design should facilitate investigations of the role of cell shape in NBL cell behavior. PMID:19609877

Comparative genome-based identification of a cell wall-anchored protein from Lactobacillus plantarum increases adhesion of Lactococcus lactis to human epithelial cells.

PubMed

Zhang, Bo; Zuo, Fanglei; Yu, Rui; Zeng, Zhu; Ma, Huiqin; Chen, Shangwu

2015-09-15

Adhesion to host cells is considered important for Lactobacillus plantarum as well as other lactic acid bacteria (LAB) to persist in human gut and thus exert probiotic effects. Here, we sequenced the genome of Lt. plantarum strain NL42 originating from a traditional Chinese dairy product, performed comparative genomic analysis and characterized a novel adhesion factor. The genome of NL42 was highly divergent from its closest neighbors, especially in six large genomic regions. NL42 harbors a total of 42 genes encoding adhesion-associated proteins; among them, cwaA encodes a protein containing multiple domains, including five cell wall surface anchor repeat domains and an LPxTG-like cell wall anchor motif. Expression of cwaA in Lactococcus lactis significantly increased its autoaggregation and hydrophobicity, and conferred the new ability to adhere to human colonic epithelial HT-29 cells by targeting cellular surface proteins, and not carbohydrate moieties, for CwaA adhesion. In addition, the recombinant Lc. lactis inhibited adhesion of Staphylococcus aureus and Escherichia coli to HT-29 cells, mainly by exclusion. We conclude that CwaA is a novel adhesion factor in Lt. plantarum and a potential candidate for improving the adhesion ability of probiotics or other bacteria of interest.

Friction-Controlled Traction Force in Cell Adhesion

PubMed Central

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

2011-01-01

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. PMID:22004739

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

2018-01-01

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.

Toll-like receptor (TLR)-1/2 triggering of multiple myeloma cells modulates their adhesion to bone marrow stromal cells and enhances bortezomib-induced apoptosis.

PubMed

Abdi, Jahangir; Mutis, Tuna; Garssen, Johan; Redegeld, Frank A

2014-01-01

In multiple myeloma (MM), the malignant plasma cells usually localize to the bone marrow where they develop drug resistance due to adhesion to stromal cells and various environmental signals. Hence, modulation of this interaction is expected to influence drug sensitivity of MM cells. Toll-like receptor (TLR) ligands have displayed heterogeneous effects on B-cell malignancies and also on MM cells in a few recent studies, but effects on adhesion and drug sensitivity of myeloma cells in the context of bone marrow stromal cells (BMSCs) have never been investigated. In the present study, we explored the modulatory effects of TLR1/2 ligand (Pam3CSK4) on adhesion of human myeloma cells to BMSCs. It is shown that TLR1/2 triggering has opposite effects in different HMCLs on their adhesion to BMSCs. Fravel, L363, UM-6, UM-9 and U266 showed increased adhesion to BMSC in parallel with an increased surface expression of integrin molecules α4 and αVβ3. OPM-1, OPM-2 and NCI-H929 showed a dose-dependent decrease in adhesion upon TLR activation following a downregulation of β7 integrin expression. Importantly, TLR1/2 triggering increased cytotoxic and apoptotic effects of bortezomib in myeloma cells independent of the effect on stromal cell adhesion. Moreover, the apoptosis-enhancing effect of Pam3CSK4 paralleled induction of cleaved caspase-3 protein in FACS analysis suggesting a caspase-dependent mechanism. Our findings uncover a novel role of TLR activation in MM cells in the context of bone marrow microenvironment. Stimulation of TLR1/2 bypasses the protective shield of BMSCs and may be an interesting strategy to enhance drug sensitivity of multiple myeloma cells.

Comparative evaluation of aggressiveness traits in staphylococcal strains from severe infections versus nasopharyngeal carriage.

PubMed

Săndulescu, Oana; Bleotu, Coralia; Matei, Lilia; Streinu-Cercel, Anca; Oprea, Mihaela; Drăgulescu, Elena Carmina; Chifiriuc, Mariana Carmen; Rafila, Alexandru; Pirici, Daniel; Tălăpan, Daniela; Dorobăţ, Olga Mihaela; Neguţ, Alina Cristina; Oţelea, Dan; Berciu, Ioana; Ion, Daniela Adriana; Codiţă, Irina; Calistru, Petre Iacob; Streinu-Cercel, Adrian

2017-01-01

Despite their commensal status, staphylococci can become problematic pathogens expressing multiple and redundant virulence factors. This study aimed to evaluate aggressiveness markers comparatively in staphylococcal strains isolated from severe infections versus asymptomatic carriage in order to identify clinically relevant bacterial traits that could easily be detected in clinical practice and could be suggestive for particular host-pathogen interactions such as cyto-adhesion or biofilm formation, ultimately orienting the clinical decision-making process. We have used in vitro phenotypic methods to assess adhesion to and invasion of eukaryotic cells, biofilm development, and expression of soluble virulence factors in 92 Staphylococcus spp. strains. The adhesion index, invasion capacity, biofilm formation and expression of soluble factors did not differ significantly between clinical and commensal strains. The major bacterial traits we found to be significantly more prevalent in clinical staphylococci were the aggregative adhesion pattern (P = 0.012), cluster adhesion (P = 0.001) and tetrad morphology (P = 0.018). The aggregative adhesion pattern was correlated with higher cyto-adhesion (P < 0.001), higher invasion capacity (P = 0.003) and lower Carmeli scores (P = 0.002). Three major bacterial traits, namely tetrad morphology, aggregative adhesion pattern, and resistance to methicillin (acronym: TAM), can be used to compute an aggressiveness score (SAS) predictive of the staphylococcal strain's virulence and capacity to initiate and develop a biofilm-driven chronic infectious process versus a fulminant acute infection, in a susceptible host. Copyright © 2016 Elsevier Ltd. All rights reserved.

Integrative systems and synthetic biology of cell-matrix adhesion sites.

PubMed

Zamir, Eli

2016-09-02

The complexity of cell-matrix adhesion convolves its roles in the development and functioning of multicellular organisms and their evolutionary tinkering. Cell-matrix adhesion is mediated by sites along the plasma membrane that anchor the actin cytoskeleton to the matrix via a large number of proteins, collectively called the integrin adhesome. Fundamental challenges for understanding how cell-matrix adhesion sites assemble and function arise from their multi-functionality, rapid dynamics, large number of components and molecular diversity. Systems biology faces these challenges in its strive to understand how the integrin adhesome gives rise to functional adhesion sites. Synthetic biology enables engineering intracellular modules and circuits with properties of interest. In this review I discuss some of the fundamental questions in systems biology of cell-matrix adhesion and how synthetic biology can help addressing them.

TES is a novel focal adhesion protein with a role in cell spreading.

PubMed

Coutts, Amanda S; MacKenzie, Elaine; Griffith, Elen; Black, Donald M

2003-03-01

Previously, we identified TES as a novel candidate tumour suppressor gene that mapped to human chromosome 7q31.1. In this report we demonstrate that the TES protein is localised at focal adhesions, actin stress fibres and areas of cell-cell contact. TES has three C-terminal LIM domains that appear to be important for focal adhesion targeting. Additionally, the N-terminal region is important for targeting TES to actin stress fibres. Yeast two-hybrid and biochemical analyses yielded interactions with several focal adhesion and/or cytoskeletal proteins including mena, zyxin and talin. The fact that TES localises to regions of cell adhesion suggests that it functions in events related to cell motility and adhesion. In support of this, we demonstrate that fibroblasts stably overexpressing TES have an increased ability to spread on fibronectin.

Orai1 as New Therapeutic Target for Inhibiting Breast Tumor Metastasis

DTIC Science & Technology

2009-09-01

includes focal adhesion assembly (formation of focal complex) and focal adhesion disassembly, we used live - cell imaging to quantify the rates of assembly...A and B) Live cell imaging of paxillin-GFP transfected MEF cells in the absence (A) or presence (B) of SKF96365. Scale bar: 10 µm. (C and D...includes focal adhesion assembly (formation of focal complexes) and focal adhesion disassembly, we used live - cell imaging to quantify the rates of focal

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.

Adhesion of liposomes: a quartz crystal microbalance study

NASA Astrophysics Data System (ADS)

Lüthgens, Eike; Herrig, Alexander; Kastl, Katja; Steinem, Claudia; Reiss, Björn; Wegener, Joachim; Pignataro, Bruno; Janshoff, Andreas

2003-11-01

Three different systems are presented, exploring the adhesion of liposomes mediated by electrostatic and lipid-protein interactions as well as molecular recognition of ligand receptor pairs. Liposomes are frequently used to gain insight into the complicated processes involving adhesion and subsequent events such as fusion and fission mainly triggered by specific proteins. We combined liposome technology with the quartz crystal microbalance (QCM) technique as a powerful tool to study the hidden interface between the membrane and functionalized surface. Electrostatic attraction and molecular recognition were employed to bind liposomes to the functionalized quartz crystal. The QCM was used to distinguish between adsorption of vesicles and rupture due to strong adhesive forces. Intact vesicles display viscoelastic behaviour, while planar lipid bilayers as a result of vesicle rupture can be modelled by a thin rigid film. Furthermore, the adhesion of cells was modelled successfully by receptor bearing liposomes. Scanning force microscopy was used to confirm the results obtained by QCM measurements.

Receptor-like Molecules on Human Intestinal Epithelial Cells Interact with an Adhesion Factor from Lactobacillus reuteri.

PubMed

Matsuo, Yosuke; Miyoshi, Yukihiro; Okada, Sanae; Satoh, Eiichi

2012-01-01

A surface protein of Lactobacillus reuteri, mucus adhesion-promoting protein (MapA), is considered to be an adhesion factor. MapA is expressed in L. reuteri strains and adheres to piglet gastric mucus, collagen type I, and human intestinal epithelial cells such as Caco-2. The aim of this study was to identify molecules that mediate the attachment of MapA from L. reuteri to the intestinal epithelial cell surface by investigating the adhesion of MapA to receptor-like molecules on Caco-2 cells. MapA-binding receptor-like molecules were detected in Caco-2 cell lysates by 2D-PAGE. Two proteins, annexin A13 (ANXA13) and paralemmin (PALM), were identified by MALDI TOF-MS. The results of a pull-down assay showed that MapA bound directly to ANXA13 and PALM. Fluorescence microscopy studies confirmed that MapA binding to ANXA13 and PALM was colocalized on the Caco-2 cell membrane. To evaluate whether ANXA13 and PALM are important for MapA adhesion, ANXA13 and PALM knockdown cell lines were established. The adhesion of MapA to the abovementioned cell lines was reduced compared with that to wild-type Caco-2 cells. These knockdown experiments established the importance of these receptor-like molecules in MapA adhesion.

CD36 Recruits α5β1 Integrin to Promote Cytoadherence of P. falciparum-Infected Erythrocytes

PubMed Central

Davis, Shevaun P.; Lee, Kristine; Gillrie, Mark R.; Roa, Lina; Amrein, Matthias; Ho, May

2013-01-01

The adhesion of Plasmodium falciparum-infected erythrocytes (IRBC) to receptors on different host cells plays a divergent yet critical role in determining the progression and outcome of the infection. Based on our ex vivo studies with clinical parasite isolates from adult Thai patients, we have previously proposed a paradigm for IRBC cytoadherence under physiological shear stress that consists of a recruitment cascade mediated largely by P-selectin, ICAM-1 and CD36 on primary human dermal microvascular endothelium (HDMEC). In addition, we detected post-adhesion signaling events involving Src family kinases and the adaptor protein p130CAS in endothelial cells that lead to CD36 clustering and cytoskeletal rearrangement which enhance the magnitude of the adhesive strength, allowing adherent IRBC to withstand shear stress of up to 20 dynes/cm2. In this study, we addressed whether CD36 supports IRBC adhesion as part of an assembly of membrane receptors. Using a combination of flow chamber assay, atomic force and confocal microscopy, we showed for the first time by loss- and gain-of function assays that in the resting state, the integrin α5β1 does not support adhesive interactions between IRBC and HDMEC. Upon IRBC adhesion to CD36, the integrin is recruited either passively as part of a molecular complex with CD36, or actively to the site of IRBC attachment through phosphorylation of Src family kinases, a process that is Ca2+-dependent. Clustering of β1 integrin is associated with an increase in IRBC recruitment as well as in adhesive strength after attachment (∼40% in both cases). The adhesion of IRBC to a multimolecular complex on the surface of endothelial cells could be of critical importance in enabling adherent IRBC to withstand the high shear stress in the microcirculations. Targeting integrins may provide a novel approach to decrease IRBC cytoadherence to microvascular endothelium. PMID:24009511

Galectin-1 induces cell adhesion to the extracellular matrix and apoptosis of non-adherent human colon cancer Colo201 cells.

PubMed

Horiguchi, Natsuko; Arimoto, Kei-ichiro; Mizutani, Atsushi; Endo-Ichikawa, Yoko; Nakada, Hiroshi; Taketani, Shigeru

2003-12-01

To isolate cDNAs for molecules involved in cell adhesion to the extracellular matrix, expression cloning with non-adherent colon cancer Colo201 cells was carried out. Four positive clones were isolated and, when sequenced, one was found to be galectin-1, a beta-galactoside-binding protein. When cultured on fibronectin-, laminin-, and collagen-coated and non-coated dishes, the adherent galectin-1 cDNA-transfected Colo201 cells increased and spread somewhat. Immunofluorescence staining revealed that galectin-1 was expressed inside and outside of Colo201 cells. The adhesion was dependent on the carbohydrate-recognition domain of galectin-1 since lactose inhibited the adhesion and exogenously-added galectin-1 caused the adhesion. PD58059, an inhibitor of mitogen-activated protein kinase, or LY294002, a phosphoinositide 3-OH kinase inhibitor, decreased the adhesion. Furthermore, the expression of galectin-1 in Colo201 cells induced apoptotic cell death, while exogenously-added galectin-1 did not cause apoptosis. These results indicate that galectin-1 plays a role in both cell-matrix interactions and the inhibition of Colo201 cell proliferation, and suggest that galectin-1 expressed in cells could be associated with apoptosis.

CXCR6-CXCL16 axis promotes prostate cancer by mediating cytoskeleton rearrangement via Ezrin activation and αvβ3 integrin clustering.

PubMed

Singh, Rajesh; Kapur, Neeraj; Mir, Hina; Singh, Nalinaksha; Lillard, James W; Singh, Shailesh

2016-02-09

Cytoskeletal rearrangement is required for migration and invasion, which are the key steps of cancer metastasis. Ezrin and integrin co-ordinate these processes by regulating cellular adhesion and cytoskeletal polymerization-depolymerization. It is also well established that chemokine-chemokine receptor axis plays a crucial role in regulating cancer cell migration and invasion. In this study, we show involvement of CXC chemokine receptor 6 (CXCR6) and its only natural ligand CXCL16 in pathobiology of prostate cancer (PCa). CXCR6 is highly expressed in PCa tissues and cell lines (LNCaP and PC3), relative to normal tissue and cells. CXCR6 expression in PCa tissues correlated with higher Gleason score. Similarly, aggressive PCa cells (PC3) show high CXCR6 compared to less aggressive LNCaP. Besides, PC3 cells show higher MMPs expression compared to LNCaP cells following CXCL16 stimulation. Intriguingly, CXCR6-CXCL16 interaction in PCa cells promotes Ezrin activation, αvβ3 integrin clustering and capping at the leading edge in FAK/PI3K/PKC dependent manner, thereby modifying cellular adhesion as well as motility. Together these results demonstrate that CXCL16 stimulation changes cytoskeletal dynamics resulting in enhanced migration, invasion and adhesion to endothelial cells, ultimately enabling PCa cells to achieve their metastatic goal.

CXCR6-CXCL16 axis promotes prostate cancer by mediating cytoskeleton rearrangement via Ezrin activation and αvβ3 integrin clustering

PubMed Central

Singh, Rajesh; Kapur, Neeraj; Mir, Hina; Singh, Nalinaksha; Lillard, James W.; Singh, Shailesh

2016-01-01

Cytoskeletal rearrangement is required for migration and invasion, which are the key steps of cancer metastasis. Ezrin and integrin co-ordinate these processes by regulating cellular adhesion and cytoskeletal polymerization-depolymerization. It is also well established that chemokine-chemokine receptor axis plays a crucial role in regulating cancer cell migration and invasion. In this study, we show involvement of CXC chemokine receptor 6 (CXCR6) and its only natural ligand CXCL16 in pathobiology of prostate cancer (PCa). CXCR6 is highly expressed in PCa tissues and cell lines (LNCaP and PC3), relative to normal tissue and cells. CXCR6 expression in PCa tissues correlated with higher Gleason score. Similarly, aggressive PCa cells (PC3) show high CXCR6 compared to less aggressive LNCaP. Besides, PC3 cells show higher MMPs expression compared to LNCaP cells following CXCL16 stimulation. Intriguingly, CXCR6-CXCL16 interaction in PCa cells promotes Ezrin activation, αvβ3 integrin clustering and capping at the leading edge in FAK/PI3K/PKC dependent manner, thereby modifying cellular adhesion as well as motility. Together these results demonstrate that CXCL16 stimulation changes cytoskeletal dynamics resulting in enhanced migration, invasion and adhesion to endothelial cells, ultimately enabling PCa cells to achieve their metastatic goal. PMID:26799186

SILAC-based proteomics of human primary endothelial cell morphogenesis unveils tumor angiogenic markers.

PubMed

Zanivan, Sara; Maione, Federica; Hein, Marco Y; Hernández-Fernaud, Juan Ramon; Ostasiewicz, Pawel; Giraudo, Enrico; Mann, Matthias

2013-12-01

Proteomics has been successfully used for cell culture on dishes, but more complex cellular systems have proven to be challenging and so far poorly approached with proteomics. Because of the complexity of the angiogenic program, we still do not have a complete understanding of the molecular mechanisms involved in this process, and there have been no in depth quantitative proteomic studies. Plating endothelial cells on matrigel recapitulates aspects of vessel growth, and here we investigate this mechanism by using a spike-in SILAC quantitative proteomic approach. By comparing proteomic changes in primary human endothelial cells morphogenesis on matrigel to general adhesion mechanisms in cells spreading on culture dish, we pinpoint pathways and proteins modulated by endothelial cells. The cell-extracellular matrix adhesion proteome depends on the adhesion substrate, and a detailed proteomic profile of the extracellular matrix secreted by endothelial cells identified CLEC14A as a matrix component, which binds to MMRN2. We verify deregulated levels of these proteins during tumor angiogenesis in models of multistage carcinogenesis. This is the most in depth quantitative proteomic study of endothelial cell morphogenesis, which shows the potential of applying high accuracy quantitative proteomics to in vitro models of vessel growth to shed new light on mechanisms that accompany pathological angiogenesis. The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium with the data set identifier PXD000359.

A hot water extract of Curcuma longa inhibits adhesion molecule protein expression and monocyte adhesion to TNF-α-stimulated human endothelial cells.

PubMed

Kawasaki, Kengo; Muroyama, Koutarou; Yamamoto, Norio; Murosaki, Shinji

2015-01-01

The recruitment of arterial leukocytes to endothelial cells is an important step in the progression of various inflammatory diseases. Therefore, its modulation is thought to be a prospective target for the prevention or treatment of such diseases. Adhesion molecules on endothelial cells are induced by proinflammatory cytokines, including tumor necrosis factor-α (TNF-α), and contribute to the recruitment of leukocytes. In the present study, we investigated the effect of hot water extract of Curcuma longa (WEC) on the protein expression of adhesion molecules, monocyte adhesion induced by TNF-α in human umbilical vascular endothelial cells (HUVECs). Treatment of HUVECs with WEC significantly suppressed both TNF-α-induced protein expression of adhesion molecules and monocyte adhesion. WEC also suppressed phosphorylation and degradation of nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IκBα) induced by TNF-α in HUVECs, suggesting that WEC inhibits the NF-κB signaling pathway.

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.

Separation of integrin-dependent adhesion from morphological changes based on differential PLC specificities.

PubMed

Wooten, D K; Teague, T K; McIntyre, B W

1999-01-01

In normal lymphocytes an inside-out signal up-regulating integrin adhesion is followed by a ligand-mediated outside-in cell spreading signal. Protein kinase C (PKC) inhibition blocks lymphocyte adherence to and spreading on fibronectin. In contrast, putative PLC inhibitors yield distinct differences with respect to adhesion and morphology. The phosphatidylinositol-specific phospholipase C (PLC) inhibitor neomycin blocked spreading of CD3/CD28-activated T cells on fibronectin by disrupting adhesion. Furthermore, when an additional inside-out signal for fibronectin adhesion is unnecessary such as with HPB-ALL T leukemic or phorbol-myristate-acetate-treated normal T cells, neomycin treatment does not alter adhesion or morphology. However, the phosphatidylcholine-specific PLC inhibitor D609 abrogates cell spreading without affecting adhesion to fibronectin in these cells as well as the CD3/CD28-activated T cells. These results strongly suggest that inside-out signaling for the integrin alpha4beta1 in lymphocytes proceeds through phosphatidylinositol-specific PLC and PKC, whereas the outside-in signal utilizes phosphatidylcholine-specific PLC and PKC.

Metastatic outgrowth encompasses COL-I, FN1, and POSTN up-regulation and assembly to fibrillar networks regulating cell adhesion, migration, and growth.

PubMed

Soikkeli, Johanna; Podlasz, Piotr; Yin, Miao; Nummela, Pirjo; Jahkola, Tiina; Virolainen, Susanna; Krogerus, Leena; Heikkilä, Päivi; von Smitten, Karl; Saksela, Olli; Hölttä, Erkki

2010-07-01

Although the outgrowth of micrometastases into macrometastases is the rate-limiting step in metastatic progression and the main determinant of cancer fatality, the molecular mechanisms involved have been little studied. Here, we compared the gene expression profiles of melanoma lymph node micro- and macrometastases and unexpectedly found no common up-regulation of any single growth factor/cytokine, except for the cytokine-like SPP1. Importantly, metastatic outgrowth was found to be consistently associated with activation of the transforming growth factor-beta signaling pathway (confirmed by phospho-SMAD2 staining) and concerted up-regulation of POSTN, FN1, COL-I, and VCAN genes-all inducible by transforming growth factor-beta. The encoded extracellular matrix proteins were found to together form intricate fibrillar networks around tumor cell nests in melanoma and breast cancer metastases from various organs. Functional analyses suggested that these newly synthesized protein networks regulate adhesion, migration, and growth of tumor cells, fibroblasts, and endothelial cells. POSTN acted as an anti-adhesive molecule counteracting the adhesive functions of FN1 and COL-I. Further, cellular FN and POSTN were specifically overexpressed in the newly forming/formed tumor blood vessels. Transforming growth factor-beta receptors and the metastasis-related matrix proteins, POSTN and FN1, in particular, may thus provide attractive targets for development of new therapies against disseminated melanoma, breast cancer, and possibly other tumors, by affecting key processes of metastasis: tumor/stromal cell migration, growth, and angiogenesis.

Modeling cell-substrate de-adhesion dynamics under fluid shear

NASA Astrophysics Data System (ADS)

Maan, Renu; Rani, Garima; Menon, Gautam I.; Pullarkat, Pramod A.

2018-07-01

Changes in cell-substrate adhesion are believed to signal the onset of cancer metastasis, but such changes must be quantified against background levels of intrinsic heterogeneity between cells. Variations in cell-substrate adhesion strengths can be probed through biophysical measurements of cell detachment from substrates upon the application of an external force. Here, we investigate, theoretically and experimentally, the detachment of cells adhered to substrates when these cells are subjected to fluid shear. We present a theoretical framework within which we calculate the fraction of detached cells as a function of shear stress for fast ramps as well as the decay in this fraction at fixed shear stress as a function of time. Using HEK and 3T3 fibroblast cells as experimental model systems, we extract characteristic force scales for cell adhesion as well as characteristic detachment times. We estimate force-scales of  ∼500 pN associated to a single focal contact, and characteristic time-scales of s representing cell-spread-area dependent mean first passage times to the detached state at intermediate values of the shear stress. Variations in adhesion across cell types are especially prominent when cell detachment is probed by applying a time-varying shear stress. These methods can be applied to characterizing changes in cell adhesion in a variety of contexts, including metastasis.

Matrix MetalloProteinases (MMPs) andTissue Inhibitors of MetalloProteinases (TIMPs): positive and negative regulators intumor cell adhesion

PubMed Central

Bourboulia, Dimitra; Stetler-Stevenson, William G.

2010-01-01

Cells adhere to one another and/or to matrices that surround them. Regulation of cell-cell (intercellular) and cell-matrix adhesion is tightly controlled in normal cells, however, defects in cell adhesion are common in the majority of humancancers. Multilateral communication among tumor cells with the extracellular matrix (ECM) and neighbor cells is accomplished through adhesion molecules, ECM components, proteolytic enzymes and their endogenous inhibitors. There is sufficient evidence to suggest that reduced adherence is a tumor cell propertyengaged during tumor progression. Tumor cells acquire the ability to change shape, detach and easily move through spaces disorganizing the normal tissue architecture. This property is due to changes in expression levels of adhesion molecules and/or due to elevated levels of secreted proteolytic enzymes, including matrix metalloproteinases (MMPs). Among other roles, MMPsdegrade the ECMand, therefore, prepare the path for tumor cells to migrate, invade and spread to distant secondary areas, where they form metastasis. Tissue Inhibitors of Metalloproteinases or TIMPs control MMP activities and, therefore, minimize matrix degradation. Both MMPs and TIMPs are involved in tissue remodeling and decisively regulate tumor cell progression including tumor angiogenesis. In this review, we describe and discuss data that support the important role of MMPs and TIMPs in cancer cell adhesion and tumor progression. PMID:20470890

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.

The extracellular adherence protein (Eap) of Staphylococcus aureus acts as a proliferation and migration repressing factor that alters the cell morphology of keratinocytes.

PubMed

Eisenbeis, Janina; Peisker, Henrik; Backes, Christian S; Bur, Stephanie; Hölters, Sebastian; Thewes, Nicolas; Greiner, Markus; Junker, Christian; Schwarz, Eva C; Hoth, Markus; Junker, Kerstin; Preissner, Klaus T; Jacobs, Karin; Herrmann, Mathias; Bischoff, Markus

2017-02-01

Staphyloccocus aureus is a major human pathogen and a common cause for superficial and deep seated wound infections. The pathogen is equipped with a large arsenal of virulence factors, which facilitate attachment to various eukaryotic cell structures and modulate the host immune response. One of these factors is the extracellular adherence protein Eap, a member of the "secretable expanded repertoire adhesive molecules" (SERAM) protein family that possesses adhesive and immune modulatory properties. The secreted protein was previously shown to impair wound healing by interfering with host defense and neovascularization. However, its impact on keratinocyte proliferation and migration, two major steps in the re-epithelialization process of wounds, is not known. Here, we report that Eap affects the proliferation and migration capacities of keratinocytes by altering their morphology and adhesive properties. In particular, treatment of non-confluent HaCaT cell cultures with Eap resulted in cell morphology changes as well as a significant reduction in cell proliferation and migration. Eap-treated HaCaT cells changed their appearance from an oblong via a trapezoid to an astral-like shape, accompanied by decreases in cell volume and cell stiffness, and exhibited significantly increased cell adhesion. Eap had a similar influence on endothelial and cancer cells, indicative for a general effect of Eap on eukaryotic cell morphology and functions. Specifically, Eap was found to interfere with growth factor-stimulated activation of the mitogen-activated protein kinase (MAPK) pathway that is known to be responsible for cell shape modulation, induction of proliferation and migration of epithelial cells. Western blot analyses revealed that Eap blocked the phosphorylation of extracellular signal-regulated kinase 1 and 2 (Erk1/2) in keratinocyte growth factor (KGF)-stimulated HaCaT cells. Together, these data add another antagonistic mechanism of Eap in wound healing, whereby the bacterial protein interferes with keratinocyte migration and proliferation. Copyright © 2017 Elsevier GmbH. All rights reserved.

Deoxycholic acid promotes development of gastroesophageal reflux disease and Barrett's oesophagus by modulating integrin-αv trafficking.

PubMed

Prichard, David O; Byrne, Anne Marie; Murphy, James O; Reynolds, John V; O'Sullivan, Jacintha; Feighery, Ronan; Doyle, Brendan; Eldin, Osama Sharaf; Finn, Stephen P; Maguire, Aoife; Duff, Deirdre; Kelleher, Dermot P; Long, Aideen

2017-12-01

The fundamental mechanisms underlying erosive oesophagitis and subsequent development of Barrett's oesophagus (BO) are poorly understood. Here, we investigated the contribution of specific components of the gastric refluxate on adhesion molecules involved in epithelial barrier maintenance. Cell line models of squamous epithelium (HET-1A) and BO (QH) were used to examine the effects of bile acids on cell adhesion to extracellular matrix proteins (Collagen, laminin, vitronectin, fibronectin) and expression of integrin ligands (α 3 , α 4, α 5 , α 6 and α ν ). Experimental findings were validated in human explant oesophageal biopsies, a rat model of gastroesophageal reflux disease (GORD) and in patient tissue microarrays. The bile acid deoxycholic acid (DCA) specifically reduced adhesion of HET-1A cells to vitronectin and reduced cell-surface expression of integrin-α ν via effects on endocytic recycling processes. Increased expression of integrin-α v was observed in ulcerated tissue in a rat model of GORD and in oesophagitis and Barrett's intestinal metaplasia patient tissue compared to normal squamous epithelium. Increased expression of integrin-α ν was observed in QH BO cells compared to HET-1A cells. QH cells were resistant to DCA-mediated loss of adhesion and reduction in cell-surface expression of integrin-α ν . We demonstrated that a specific component of the gastric refluxate, DCA, affects the epithelial barrier through modulation of integrin α ν expression, providing a novel mechanism for bile acid-mediated erosion of oesophageal squamous epithelium and promotion of BO. Strategies aimed at preventing bile acid-mediated erosion should be considered in the clinical management of patients with GORD. © 2017 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.