scholarly journals Cell based strain stiffening of a non-fibrous matrix as organizing principle for morphogenesis

2019 ◽  
Author(s):  
Daniel Rüdiger ◽  
Kerstin Kick ◽  
Andriy Goychuk ◽  
Angelika M. Vollmar ◽  
Erwin Frey ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Pattern Formation ◽  
Basement Membrane ◽  
Self Assembly ◽  
Matrix Material ◽  
Cell Contacts ◽  
Cell Contractility ◽  
Cell Cell

AbstractEndothelial tube formation on a reconstituted extracellular matrix (Matrigel) is a well-established in vitro model for studying the processes of angiogenesis and vasculogenesis. However, to date, the organizing principles that underlie the morphogenesis of this network, and that shape the initial process of cell-cell finding remain elusive. Furthermore, it is unclear how in vitro results extrapolate to in vivo morphogenesis. Here, we identify a mechanism that allows cells to form networks by mechanically reorganizing and stiffening their extracellular matrix, independent of chemical guidance cues. Interestingly, we find that this cellular self-organization strongly depends on the connectivity and topology of the surrounding matrix, as well as on cell contractility and cell density. Cells rearrange the matrix, and form bridges of matrix material that are stiffer than their surroundings, thus creating a durotactic track for the initiation of cell-cell contacts. This contractility-based communication via strain stiffening and matrix rearrangement might be a general organizing principle during tissue development or regeneration.Significance StatementIn addition to chemotactic gradients, biomechanical cues are important for guiding biological pattern formation. Self-assembly of cells has often been ascribed to reorganization of collagen fibres in the extracellular matrix. However, the basement membrane surrounding vascular cells, is per se non-fibrous. Here, we find that this difference in matrix topology can crucially influence cell behaviour and pattern formation. In a homogeneously elastic environment like the basement membrane, endothelial cells rearrange extracellular matrix proteins by contractile force, forming stiff intercellular bridges as tracks for cell-cell contacts. Our findings shine some light why there is a lot of merit in having multiple approaches to matrix elasticity (like continuum theories or dilated network approaches). Our observations might help to understand why vascular nets look different in different tissues and after rearrangement of the extracellular matrix during disease.

Interactions between mesoderm cells and the extracellular matrix following gastrulation in the chick embryo

1991 ◽  
Vol 99 (2) ◽  
pp. 431-441
Author(s):  
A.J. Brown ◽  
E.J. Sanders
Keyword(s):  
Extracellular Matrix ◽  
Chick Embryo ◽  
Basement Membrane ◽  
Primitive Streak ◽  
Cell Binding ◽  
Fab Fragment ◽  
Fibronectin Receptor ◽  
In Vitro Methods

In the gastrulating chick embryo, the mesoderm cells arise from the epiblast layer by ingression through the linear accumulation of cells called the primitive streak. The mesoderm cells emerge from the streak with a fibroblastic morphology and proceed to move away from the mid-line of the embryo using, as a substratum, the basement membrane of the overlying epiblast and the extracellular matrix. We have investigated the roles of fibronectin and laminin as putative substrata for mesoderm cells using complementary in vivo and in vitro methods. We have microinjected agents into the tissue space adjacent to the primitive streak of living embryos and, after further incubation, we have examined the embryos for perturbation of the mesoderm tissue. These agents were: cell-binding regions from fibronectin (RGDS) and laminin (YIGSR), antibodies to these glycoproteins, and a Fab' fragment of the antibody to fibronectin. We find that RGDS, antibody to fibronectin, and the Fab' fragment cause a decrease in the number of mesoderm cells spread on the basement membrane, and a perturbation of cell shape suggesting locomotory impairment. No such influence was seen with YIGSR or antibodies to laminin. These results were extended using in vitro methods in which mesoderm cells were cultured in fibronectin-free medium on fibronectin or laminin in the presence of various agents. These agents were: RGDS; YIGSR; antibodies to fibronectin, fibronectin receptor, laminin and vitronectin; and a Fab' fragment of the fibronectin antiserum. We find that cell attachment and spreading on fibronectin is impaired by RGDS, antiserum to fibronectin, the Fab' fragment of fibronectin antiserum, and antiserum to fibronectin receptor. The results suggest that although the RGDS site in fibronectin is important, it is probably not the only fibronectin cell-binding site involved in mediating the behaviour of the mesoderm cells. Cells growing on laminin were perturbed by YIGSR, RGDS and antibodies to laminin, suggesting that mesoderm cells are able to recognise at least two sites in the laminin molecule. We conclude that the in vivo dependence of mesoderm cells on fibronectin is confirmed, but that although these cells have the ability to recognise sites in laminin as mediators of attachment and spreading, the in vivo role of this molecule in mesoderm morphogenesis is not yet certain.

scholarly journals Signature-Tagged Mutagenesis of Klebsiella pneumoniae To Identify Genes That Influence Biofilm Formation on Extracellular Matrix Material

2006 ◽  
Vol 74 (8) ◽  
pp. 4590-4597 ◽  
Author(s):  
Jennifer D. Boddicker ◽  
Rebecca A. Anderson ◽  
Jennifer Jagnow ◽  
Steven Clegg
Keyword(s):  
Extracellular Matrix ◽  
Klebsiella Pneumoniae ◽  
Biofilm Formation ◽  
Matrix Material ◽  
Infection Process ◽  
Bladder Epithelium ◽  
Tract Infections ◽  
Type 3

ABSTRACT Klebsiella pneumoniae causes urinary tract infections, respiratory tract infections, and septicemia in susceptible individuals. Strains of Klebsiella frequently produce extended-spectrum beta-lactamases, and infections with these strains can lead to relatively high mortality rates (approximately 15%). Other virulence factors include production of an antiphagocytic capsule and outer membrane lipopolysaccharide (LPS), which mediates serum resistance, as well as fimbriae on the surface of the bacteria. Type 1 fimbriae mediate adherence to many types of epithelial cells and may facilitate adherence of the bacteria to the bladder epithelium. Type 3 fimbriae can bind in vitro to the extracellular matrix of urinary and respiratory tissues, suggesting that they mediate binding to damaged epithelial surfaces. In addition, type 3 fimbriae are required for biofilm formation by Klebsiella pneumoniae on plastics and human extracellular matrix; thus, they may facilitate the formation of treatment-resistant biofilm on indwelling plastic devices, such as catheters and endotracheal tubing. The presence of these devices may cause tissue damage, allowing Klebsiella to grow as a biofilm on exposed tissue basement membrane components. Though in vivo biofilm growth may be an important step in the infection process, little is known about the genetic factors required for biofilm formation by Klebsiella pneumoniae. Thus, we performed signature-tagged mutagenesis to identify factors produced by K. pneumoniae strain 43816 that are required for biofilm formation. We identified mutations in the cps capsule gene cluster, previously unidentified transcriptional regulators, fimbrial, and sugar phosphotransferase homologues, as well as genetic loci of unknown function, that affect biofilm formation.

Myogel, a Novel, Basement Membrane-Rich, Extracellular Matrix Derived from Skeletal Muscle, Is Highly Adipogenic in vivo and in vitro

2008 ◽  
Vol 188 (4) ◽  
pp. 347-358 ◽  
Author(s):  
K.M. Abberton ◽  
S.K. Bortolotto ◽  
A.A. Woods ◽  
M. Findlay ◽  
W.A. Morrison ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Extracellular Matrix ◽  
Basement Membrane

scholarly journals Sertoli cell binding to isolated testicular basement membrane.

1986 ◽  
Vol 103 (3) ◽  
pp. 1109-1119 ◽  
Author(s):  
G C Enders ◽  
J H Henson ◽  
C F Millette
Keyword(s):  
Basement Membrane ◽  
Sertoli Cell ◽  
Basal Lamina ◽  
Sertoli Cells ◽  
Matrix Material ◽  
Three Dimensional ◽  
Myoid Cells ◽  
Cell Binding

We have examined the adhesion of primary Sertoli cells to a seminiferous tubule basement membrane (STBM) preparation in vitro. The STBM isolation procedure (Watanabe, T.K., L.J. Hansen, N.K. Reddy, Y.S. Kanwar, and J.K. Reddy, 1984, Cancer Res., 44:5361-5368) yields segments of STBM that retain their histotypic form in both three-dimensional tubular geometry and ultrastructural appearance. The STBM sleeves contain two laminae: a thick, inner basal lamina that was formed in vivo between Sertoli cells and peritubular myoid cells; and a thinner, outer basal lamina that was formed between myoid cells and sinusoidal endothelial cells. Characterization by immunofluorescence and SDS PAGE revealed that the isolated STBM retained fibronectin, laminin, and putative type IV collagen among its many components. When the STBM sleeves were gently shaken with an enriched fraction of primary Sertoli cells, the Sertoli cells bound preferentially to the lumenal basal lamina at the ends of the STBM sleeves. Few Sertoli cells bound to either the outer basal lamina of the STBM sleeves or to vascular extracellular matrix material which contaminated the STBM preparation. 3T3 cells, in contrast, bound to all surfaces of the STBM sleeves. Pretreatment of the STBM sleeves with proteases, 0.1 M Na metaperiodate, 4 M guanidine HCl, or heating to 80 degrees-90 degrees C inhibited lumenal Sertoli cell binding, but binding was not inhibited by chondroitinase ABC, heparinase, hyaluronidase, or 4 M NaCl. The lumenal Sertoli cell binding occurred in the presence or absence of added soluble laminin, but not fibronectin. The addition of soluble laminin, but not fibronectin, restored random binding of Sertoli cells to trypsinized STBM sleeves. Our in vitro model system indicates that Sertoli cells recognize differences in two basal laminae produced in vivo on either side of myoid cells.

scholarly journals Vinculin Is Part of the Cadherin–Catenin Junctional Complex: Complex Formation between α-Catenin and Vinculin

1998 ◽  
Vol 141 (3) ◽  
pp. 755-764 ◽  
Author(s):  
Elisabeth E. Weiss ◽  
Martina Kroemker ◽  
Angelika-H. Rüdiger ◽  
Brigitte M. Jockusch ◽  
Manfred Rüdiger
Keyword(s):  
Complex Formation ◽  
Transmembrane Protein ◽  
Adherens Junction ◽  
Focal Adhesions ◽  
Junctional Complex ◽  
Cell Contacts ◽  
Junction Protein ◽  
Cell Cell

In epithelial cells, α-, β-, and γ-catenin are involved in linking the peripheral microfilament belt to the transmembrane protein E-cadherin. α-Catenin exhibits sequence homologies over three regions to vinculin, another adherens junction protein. While vinculin is found in cell–matrix and cell–cell contacts, α-catenin is restricted to the latter. To elucidate, whether vinculin is part of the cell–cell junctional complex, we investigated complex formation and intracellular targeting of vinculin and α-catenin. We show that α-catenin colocalizes at cell–cell contacts with endogenous vinculin and also with the transfected vinculin head domain forming immunoprecipitable complexes. In vitro, the vinculin NH2-terminal head binds to α-catenin, as seen by immunoprecipitation, dot overlay, cosedimentation, and surface plasmon resonance measurements. The Kd of the complex was determined to 2–4 × 10−7 M. As seen by overlays and affinity mass spectrometry, the COOH-terminal region of α-catenin is involved in this interaction. Complex formation of vinculin and α-catenin was challenged in transfected cells. In PtK2 cells, intact α-catenin and α-catenin1-670, harboring the β-catenin– binding site, were directed to cell–cell contacts. In contrast, α-catenin697–906 fragments were recruited to cell–cell contacts, focal adhesions, and stress fibers. Our results imply that in vivo α-catenin, like vinculin, is tightly regulated in its ligand binding activity.

scholarly journals Extracellular Matrix Determines Biomechanical Properties of Chondrospheres during Their Maturation In Vitro

Cartilage ◽  
2018 ◽  
Vol 11 (4) ◽  
pp. 521-531 ◽  
Author(s):  
Nikolai P. Omelyanenko ◽  
Pavel A. Karalkin ◽  
Elena A. Bulanova ◽  
Elizaveta V. Koudan ◽  
Vladislav A. Parfenov ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Self Assembly ◽  
Biomechanical Properties ◽  
Culture Conditions ◽  
Secant Modulus ◽  
Structural Determinants ◽  
Maturation In Vitro

Objective Chondrospheres represent a variant of tissue spheroids biofabricated from chondrocytes. They are already being used in clinical trials for cartilage repair; however, their biomechanical properties have not been systematically investigated yet. The aim of our study was to characterize chondrospheres in long-term in vitro culture conditions for morphometric changes, biomechanical integrity, and their fusion and spreading kinetics. Results It has been demonstrated that the increase in chondrospheres secant modulus of elasticity is strongly associated with the synthesis and accumulation of extracellular matrix. Additionally, significant interplay has been found between biomechanical properties of tissue spheroids and their fusion kinetics in contrast to their spreading kinetics. Conclusions Extracellular matrix is one of the main structural determinants of chondrospheres biomechanical properties during chondrogenic maturation in vitro. The estimation of tissue spheroids’ physical behavior in vitro prior to operative treatment can be used to predict and potentially control fusogenic self-assembly process after implantation in vivo.

scholarly journals Dismantling Cell–Cell Contacts during Apoptosis Is Coupled to a Caspase-dependent Proteolytic Cleavage of β-Catenin

1997 ◽  
Vol 139 (3) ◽  
pp. 759-771 ◽  
Author(s):  
Claudio Brancolini ◽  
Dean Lazarevic ◽  
Joe Rodriguez ◽  
Claudio Schneider
Keyword(s):  
Cell Death ◽  
Cell Adhesion ◽  
Actin Cytoskeleton ◽  
Caspase 3 ◽  
Cell Types ◽  
Cell Contacts ◽  
Carboxy Terminal ◽  
Cell Cell

Cell death by apoptosis is a tightly regulated process that requires coordinated modification in cellular architecture. The caspase protease family has been shown to play a key role in apoptosis. Here we report that specific and ordered changes in the actin cytoskeleton take place during apoptosis. In this context, we have dissected one of the first hallmarks in cell death, represented by the severing of contacts among neighboring cells. More specifically, we provide demonstration for the mechanism that could contribute to the disassembly of cytoskeletal organization at cell–cell adhesion. In fact, β-catenin, a known regulator of cell–cell adhesion, is proteolytically processed in different cell types after induction of apoptosis. Caspase-3 (cpp32/apopain/yama) cleaves in vitro translated β-catenin into a form which is similar in size to that observed in cells undergoing apoptosis. β-Catenin cleavage, during apoptosis in vivo and after caspase-3 treatment in vitro, removes the amino- and carboxy-terminal regions of the protein. The resulting β-catenin product is unable to bind α-catenin that is responsible for actin filament binding and organization. This evidence indicates that connection with actin filaments organized at cell–cell contacts could be dismantled during apoptosis. Our observations suggest that caspases orchestrate the specific and sequential changes in the actin cytoskeleton occurring during cell death via cleavage of different regulators of the microfilament system.

scholarly journals RhoA is dispensable for skin development, but crucial for contraction and directed migration of keratinocytes

2011 ◽  
Vol 22 (5) ◽  
pp. 593-605 ◽  
Author(s):  
Ben Jackson ◽  
Karine Peyrollier ◽  
Esben Pedersen ◽  
Astrid Basse ◽  
Richard Karlsson ◽  
...  
Keyword(s):  
Normal Skin ◽  
Cell Spreading ◽  
Fiber Formation ◽  
Cell Contraction ◽  
Skin Development ◽  
Cell Contacts ◽  
Directed Migration ◽  
Cell Cell

RhoA is a small guanosine-5’-triphosphatase (GTPase) suggested to be essential for cytokinesis, stress fiber formation, and epithelial cell–cell contacts. In skin, loss of RhoA was suggested to underlie pemphigus skin blistering. To analyze RhoA function in vivo, we generated mice with a keratinocyte-restricted deletion of the RhoA gene. Despite a severe reduction of cofilin and myosin light chain (MLC) phosphorylation, these mice showed normal skin development. Primary RhoA-null keratinocytes, however, displayed an increased percentage of multinucleated cells, defective maturation of cell–cell contacts. Furthermore we observed increased cell spreading due to impaired RhoA-ROCK (Rho-associated protein kinase)-MLC phosphatase-MLC–mediated cell contraction, independent of Rac1. Rho-inhibiting toxins further increased multinucleation of RhoA-null cells but had no significant effect on spreading, suggesting that RhoB and RhoC have partially overlapping functions with RhoA. Loss of RhoA decreased directed cell migration in vitro caused by reduced migration speed and directional persistence. These defects were not related to the decreased cell contraction and were independent of ROCK, as ROCK inhibition by Y27632 increased directed migration of both control and RhoA-null keratinocytes. Our data indicate a crucial role for RhoA and contraction in regulating cell spreading and a contraction-independent function of RhoA in keratinocyte migration. In addition, our data show that RhoA is dispensable for skin development.

Extracellular matrix modulation of endothelial cell shape and motility following injury in vitro

1985 ◽  
Vol 73 (1) ◽  
pp. 19-32
Author(s):  
W.C. Young ◽  
I.M. Herman
Keyword(s):  
Extracellular Matrix ◽  
Basement Membrane ◽  
Fluorescence Microscopy ◽  
Type Iv Collagen ◽  
Type I ◽  
Post Injury ◽  
Type Iv ◽  
Interstitial Collagens

We utilized fluorescence microscopy and affinity-purified antibodies to probe the form and function of cytoplasmic actin in endothelial cells (EC) recovering from injury and grown on extracellular matrices in vitro. Bovine aortic EC were seeded onto glass microscope coverslips that had been coated with either BSA, fibronectin, type I and III (interstitial) collagens, type IV (basement membrane) collagen or gelatin. After EC that had been grown on glass, glass-BSA or extracellular matrix-coated coverslips reached confluence, a 300–400 micron zone of cells was mechanically removed to stimulate EC migration and proliferation. Post-injury EC movements were monitored with time-lapse, phase-contrast videomicrography before fixation for actin localization with fluorescence microscopy using affinity-purified antibodies. We found that the number of stress fibres within EC was inversely proportional to the rate of movement; and, the rates of movement for EC grown on glass or glass-BSA were approximately eight times faster than EC grown on gelatin or type IV collagen (X velocity = 0.5 micron/min versus 0.06 micron/min). EC movements on fibronectin and interstitial collagens were similar (X velocity = 0.2 micron/min). These results suggest that extracellular matrix molecules modulate EC stress fibre expression, thereby producing alterations in the cytoskeleton and the resultant EC movements that follow injury in vitro. Moreover, the induction of stress fibres in the presence of basement membrane (type IV) collagen may explain the failure of aortic EC to migrate and repopulate wounded regions of intima during atherogenesis in vivo.

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