Integrin-Mediated Fibroblast Adhesion Strength: Role of the β1 Subunit

1993 ◽  
Vol 331 ◽  
Author(s):  
Kelly A. Ward ◽  
Jun-Lin Guan ◽  
Daniel A. Hammer
Keyword(s):  
Extracellular Matrix ◽  
Adhesion Strength ◽  
Cytoplasmic Domain ◽  
Integrin Receptors ◽  
Substrate Adhesion ◽  
Focal Contacts ◽  
Cell Substrate ◽  
Extracellular Matrix Molecules ◽  
Integrin Ligand ◽  
Cell Substrate Adhesion

AbstractCell-substratum adhesion is important in wound healing [4], embryogenic development [11], tissue architecture [6], and metastasis [7]. Integrins constitute a major class of heterodimeric cell-surface glycoproteins involved in receptor-mediated adhesion to the extracellular matrix (ECM). Focal contacts are regions of the cell-substratum adhesion in which clusters of integrin receptors connect the cytoskeleton to extracellular matrix molecules such as fibronectin. Focal contacts strengthen cell-substrate adhesion, and are sites of biochemical activity. Since cell adhesion strength in part depends on the cell's ability to cluster receptors and cytoskeleton into focal contacts, the integrity of the focal contact, and hence a cell's adhesive strength, will depend both on integrin-cytoskeletal binding as well as integrin-ligand binding.Using a centrifugation assay, we have quantified cell-substratum adhesion strength of mouse 3T3 cells transfected with the avian β1 integrin receptor (wild type), including various deletion mutants of its cytoplasmic domain, to surfaces containing varying concentrations of CSAT, a monoclonal antibody against the extracellular domain of the avian β1 subunit. For all the transfectants, adhesion strength decreases with decreasing CSAT concentration and increasing centrifugal strength. Different truncations of the cytoplasmic domain lead to different levels of adhesion. There is no simple correlation between the length of the cytoplasmic domain and the strength of adhesion.

scholarly journals Regulation of epithelial cell organization by tuning cell–substrate adhesion

2015 ◽  
Vol 7 (10) ◽  
pp. 1228-1241 ◽  
Author(s):  
Andrea Ravasio ◽  
Anh Phuong Le ◽  
Thuan Beng Saw ◽  
Victoria Tarle ◽  
Hui Ting Ong ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Particle Image ◽  
Substrate Adhesion ◽  
Cell Substrate ◽  
Image Velocimetry ◽  
Cell Organization ◽  
Cell Substrate Adhesion

Combining live cell imaging, particle image velocimetry and numerical simulations, we show the role of extracellular matrix and intercellular adhesion on the expansion of epithelial cells.

scholarly journals Balance between cell−substrate adhesion and myosin contraction determines the frequency of motility initiation in fish keratocytes

2015 ◽  
Vol 112 (16) ◽  
pp. 5045-5050 ◽  
Author(s):  
Erin Barnhart ◽  
Kun-Chun Lee ◽  
Greg M. Allen ◽  
Julie A. Theriot ◽  
Alex Mogilner
Keyword(s):  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Adhesion Strength ◽  
Network Flow ◽  
Critical Threshold ◽  
Stable States ◽  
Flow Rates ◽  
Substrate Adhesion ◽  
Cell Substrate ◽  
Cell Substrate Adhesion

Cells are dynamic systems capable of spontaneously switching among stable states. One striking example of this is spontaneous symmetry breaking and motility initiation in fish epithelial keratocytes. Although the biochemical and mechanical mechanisms that control steady-state migration in these cells have been well characterized, the mechanisms underlying symmetry breaking are less well understood. In this work, we have combined experimental manipulations of cell−substrate adhesion strength and myosin activity, traction force measurements, and mathematical modeling to develop a comprehensive mechanical model for symmetry breaking and motility initiation in fish epithelial keratocytes. Our results suggest that stochastic fluctuations in adhesion strength and myosin localization drive actin network flow rates in the prospective cell rear above a critical threshold. Above this threshold, high actin flow rates induce a nonlinear switch in adhesion strength, locally switching adhesions from gripping to slipping and further accelerating actin flow in the prospective cell rear, resulting in rear retraction and motility initiation. We further show, both experimentally and with model simulations, that the global levels of adhesion strength and myosin activity control the stability of the stationary state: The frequency of symmetry breaking decreases with increasing adhesion strength and increases with increasing myosin contraction. Thus, the relative strengths of two opposing mechanical forces—contractility and cell−substrate adhesion—determine the likelihood of spontaneous symmetry breaking and motility initiation.

Integrin Receptors and Epiligrin in Cell-Cell and Cell-Substrate Adhesion in the Epidermis

2017 ◽  
pp. 147-176
Author(s):  
William G. Carter ◽  
Susana G. Gil ◽  
Banu E. Symington ◽  
Tod A. Brown ◽  
Shunji Hattori ◽  
...  
Keyword(s):  
Integrin Receptors ◽  
Substrate Adhesion ◽  
Cell Substrate ◽  
Cell Substrate Adhesion ◽  
Cell Cell

scholarly journals Functional mapping of cytotactin: proteolytic fragments active in cell-substrate adhesion.

1988 ◽  
Vol 107 (6) ◽  
pp. 2329-2340 ◽  
Author(s):  
D R Friedlander ◽  
S Hoffman ◽  
G M Edelman
Keyword(s):  
Extracellular Matrix ◽  
Polyclonal Antibody ◽  
Limited Proteolysis ◽  
Cell Binding ◽  
Fab Fragments ◽  
Substrate Adhesion ◽  
Cell Substrate ◽  
A Cell ◽  
Fraction I ◽  
Cell Substrate Adhesion

Cytotactin is an extracellular matrix glycoprotein with a restricted distribution during development. In electron microscopic images, it appears as a hexabrachion with six arms extending from a central core. Cytotactin binds to other extracellular matrix proteins including a chondroitin sulfate proteoglycan (CTB proteoglycan) and fibronectin. Although cytotactin binds to a variety of cells including fibroblasts and neurons, in some cases it causes cells in culture to round up and it inhibits their migration. To relate these various effects of cytotactin on cell behavior to its binding regions, we have examined its ability to support cell-substrate adhesion and have mapped its cell-binding function onto its structure. In a cell-substrate adhesion assay, fibroblasts bound to cytotactin but remained round. In contrast, they both attached and spread on fibronectin. Neither neurons nor glia bound to cytotactin in this assay. In an assay in which cell-substrate contact was initiated by centrifugation, however, neurons and glia bound well to cytotactin; this binding was blocked by specific anti-cytotactin antibodies. The results suggest that neurons and glia can bind to cytotactin-coated substrates and that these cells, like fibroblasts, possess cell surface ligands for cytotactin. After applying methods of limited proteolysis and fractionation, these assays were used to map the binding functions of cytotactin onto its structure. Fragments produced by limited proteolysis were fractionated into two major pools: one (fraction I) contained disulfide-linked oligomers of a 100-kD fragment and two minor related fragments, and the second (fraction II) contained monomeric 90- and 65-kD fragments. The 90- and 65-kD fragments in fraction II were closely related to each other and were structurally and immunologically distinct from the fragments in fraction I. Only components in fraction I were recognized by mAb M1, which binds to an epitope located in the proximal portion of the arms of the hexabrachion and by a polyclonal antibody prepared against a 75-kD CNBr fragment of intact cytotactin. A mAb (1D8) and a polyclonal antibody prepared against a 35-kD CNBr fragment of cytotactin only recognized components present in fraction II. In cell-binding experiments, fibroblasts, neurons, and glia each adhered to substrates coated with fraction II, but did not adhere to substrates coated with fraction I. Fab fragments of the antibody to the 35-kD CNBr fragment strongly inhibited the binding of cells to cytotactin, supporting the conclusion that fraction II contains a cell-binding region. In addition, Fab fragments of this antibody inhibited the binding of cytotactin to CTB pr

scholarly journals Regulation of cell-substrate adhesion by proteoglycans immobilized on extracellular substrates

1989 ◽  
Vol 264 (14) ◽  
pp. 8012-8018 ◽  
Author(s):  
M Yamagata ◽  
S Suzuki ◽  
S K Akiyama ◽  
K M Yamada ◽  
K Kimata
Keyword(s):  
Substrate Adhesion ◽  
Cell Substrate ◽  
Cell Substrate Adhesion

scholarly journals A GTPase controls cell-substrate adhesion in Xenopus XTC fibroblasts.

1992 ◽  
Vol 118 (5) ◽  
pp. 1235-1244 ◽  
Author(s):  
M H Symons ◽  
T J Mitchison
Keyword(s):  
Control Cell ◽  
Response To Treatment ◽  
Nucleotide Analogs ◽  
Cell Contractility ◽  
Cell Rounding ◽  
Substrate Adhesion ◽  
Cell Substrate ◽  
Adhesive Interactions ◽  
Cell Substrate Adhesion ◽  
Gamma S

Cell-substrate adhesion is crucial at various stages of development and for the maintenance of normal tissues. Little is known about the regulation of these adhesive interactions. To investigate the role of GTPases in the control of cell morphology and cell-substrate adhesion we have injected guanine nucleotide analogs into Xenopus XTC fibroblasts. Injection of GTP gamma S inhibited ruffling and increased spreading, suggesting an increase in adhesion. To further investigate this, we made use of GRGDSP, a peptide which inhibits binding of integrins to vitronectin and fibronectin. XTC fibroblasts injected with non-hydrolyzable analogs of GTP took much more time to round up than mock-injected cells in response to treatment with GRGDSP, while GDP beta S-injected cells rounded up in less time than controls. Injection with GTP gamma S did not inhibit cell rounding induced by trypsin however, showing that cell contractility is not significantly affected by the activation of GTPases. These data provide evidence for the existence of a GTPase which can control cell-substrate adhesion from the cytoplasm. Treatment of XTC fibroblasts with the phorbol ester 12-o-tetradecanoylphorbol-13-acetate reduced cell spreading and accelerated cell rounding in response to GRGDSP, which is essentially opposite to the effect exerted by non-hydrolyzable GTP analogs. These results suggest the existence of at least two distinct pathways controlling cell-substrate adhesion in XTC fibroblasts, one depending on a GTPase and another one involving protein kinase C.

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