scholarly journals Dystroglycan proteolysis is conformationally-regulated and disrupted by disease-associated mutations

2018 ◽  
Author(s):  
Amanda N. Hayward ◽  
Wendy R. Gordon
Keyword(s):  
Extracellular Matrix ◽  
Cell Migration ◽  
Muscular Dystrophy ◽  
Actin Cytoskeleton ◽  
Blood Brain Barrier ◽  
Muscle Cells ◽  
Matrix Metalloproteases ◽  
Neural Cells ◽  
Cellular Phenotype ◽  
Adhesion Receptor

AbstractThe adhesion receptor dystroglycan provides a critical mechanical link between the extracellular matrix (ECM) and the actin cytoskeleton to help muscle cells withstand contraction and neural cells maintain the blood brain barrier. Disrupting the link is associated with diseases such as cancer and muscular dystrophy. Proteolysis of dystroglycan by Matrix Metalloproteases (MMPs) also breaks the mechanical anchor and is amplified in several pathogenic states. We use a combination of biochemical and cell-based assays to show that dystroglycan proteolysis is conformationally regulated by an extracellular, juxtamembrane “proteolysis domain”, comprised of tandem Ig-like and SEA-like domains. The intact proteolysis domain is resistant to MMP cleavage, but structurally-disruptive muscular dystrophy-related mutations sensitize dystroglycan to proteolysis. Moreover, increased dystroglycan proteolysis correlates with faster cell migration, linking proteolysis to a disease-relevant cellular phenotype. Intriguingly, previously uncharacterized cancer-associated mutations that map to the proteolysis domain similarly lead to increases in proteolysis and rates of cell migration, potentially revealing a new pathogenic mechanism in cancer.

TGF beta 1 promotes actin cytoskeleton reorganization and migratory phenotype in epithelial tracheal cells in primary culture

1996 ◽  
Vol 109 (9) ◽  
pp. 2207-2219 ◽  
Author(s):  
S. Boland ◽  
E. Boisvieux-Ulrich ◽  
O. Houcine ◽  
A. Baeza-Squiban ◽  
M. Pouchelet ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Cell Proliferation ◽  
Cell Migration ◽  
Epithelial Cells ◽  
Actin Cytoskeleton ◽  
Primary Culture ◽  
Tgf Beta ◽  
Cytoskeleton Reorganization ◽  
Extracellular Matrix Components ◽  
Migratory Phenotype

In the present study we have investigated the effects of transforming growth factor beta (TGF beta 1) on rabbit tracheal epithelial cells in primary culture, with respect to cell proliferation and differentiation. Epithelial tracheal cells derived from an explant plated on an extracellular matrix, formed an outgrowth resulting from cell division and cell migration. TGF beta 1 treatment produced a negative effect on cell proliferation, but in contrast, promoted a marked enhancement of cell migration and increase in outgrowth surface. TGF beta 1 induced marked cell shape changes, including cell spreading and lack of stratification, associated with reduced cell-cell contacts and increased cell-substratum anchorage, as seen by electron microscopic observations. Immunocytological studies demonstrated major TGF beta 1-induced actin cytoskeleton reorganization, corresponding to the development of a basal stress fiber network and decrease of the annular cell border, without affecting the tight junctions. The migratory phenotype was approached by microcinematography which clearly showed that TGF beta 1 triggered a stimulatory effect on migration of epithelial cells, determined using an image analyzing system. Present findings suggest a beneficial role for TGF beta 1 during wound healing in providing the acquisition of a migratory phenotype, with a higher capacity to migrate either on collagen or on different extracellular matrix components including laminin and fibronectin. Conversely, present data are not consistent with a squamous response to TGF beta 1, since metaplastic differentiation did not occur, as characterized by cytokeratin expression and cross-linked envelopes formation.

scholarly journals A cytoskeletal clutch mediates cellular force transmission in a soft, three-dimensional extracellular matrix

2017 ◽  
Vol 28 (14) ◽  
pp. 1959-1974 ◽  
Author(s):  
Leanna M. Owen ◽  
Arjun S. Adhikari ◽  
Mohak Patel ◽  
Peter Grimmer ◽  
Natascha Leijnse ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Cell Migration ◽  
Actin Cytoskeleton ◽  
Dynamic Equilibrium ◽  
Three Dimensional ◽  
Time Lapse ◽  
Dermal Fibroblasts ◽  
Force Transmission ◽  
Ecm Remodeling

The ability of cells to impart forces and deformations on their surroundings underlies cell migration and extracellular matrix (ECM) remodeling and is thus an essential aspect of complex, metazoan life. Previous work has resulted in a refined understanding, commonly termed the molecular clutch model, of how cells adhering to flat surfaces such as a microscope coverslip transmit cytoskeletally generated forces to their surroundings. Comparatively less is known about how cells adhere to and exert forces in soft, three-dimensional (3D), and structurally heterogeneous ECM environments such as occur in vivo. We used time-lapse 3D imaging and quantitative image analysis to determine how the actin cytoskeleton is mechanically coupled to the surrounding matrix for primary dermal fibroblasts embedded in a 3D fibrin matrix. Under these circumstances, the cytoskeletal architecture is dominated by contractile actin bundles attached at their ends to large, stable, integrin-based adhesions. Time-lapse imaging reveals that α-actinin-1 puncta within actomyosin bundles move more quickly than the paxillin-rich adhesion plaques, which in turn move more quickly than the local matrix, an observation reminiscent of the molecular clutch model. However, closer examination did not reveal a continuous rearward flow of the actin cytoskeleton over slower moving adhesions. Instead, we found that a subset of stress fibers continuously elongated at their attachment points to integrin adhesions, providing stable, yet structurally dynamic coupling to the ECM. Analytical modeling and numerical simulation provide a plausible physical explanation for this result and support a picture in which cells respond to the effective stiffness of local matrix attachment points. The resulting dynamic equilibrium can explain how cells maintain stable, contractile connections to discrete points within ECM during cell migration, and provides a plausible means by which fibroblasts contract provisional matrices during wound healing.

scholarly journals Targeting and transport: How microtubules control focal adhesion dynamics

2012 ◽  
Vol 198 (4) ◽  
pp. 481-489 ◽  
Author(s):  
Samantha Stehbens ◽  
Torsten Wittmann
Keyword(s):  
Extracellular Matrix ◽  
Cell Migration ◽  
Focal Adhesion ◽  
Molecular Mechanisms ◽  
Rho Gtpase ◽  
Focal Adhesions ◽  
Matrix Metalloproteases ◽  
Force Generation ◽  
Diverse Group ◽  
Directional Cell Migration

Directional cell migration requires force generation that relies on the coordinated remodeling of interactions with the extracellular matrix (ECM), which is mediated by integrin-based focal adhesions (FAs). Normal FA turnover requires dynamic microtubules, and three members of the diverse group of microtubule plus-end-tracking proteins are principally involved in mediating microtubule interactions with FAs. Microtubules also alter the assembly state of FAs by modulating Rho GTPase signaling, and recent evidence suggests that microtubule-mediated clathrin-dependent and -independent endocytosis regulates FA dynamics. In addition, FA-associated microtubules may provide a polarized microtubule track for localized secretion of matrix metalloproteases (MMPs). Thus, different aspects of the molecular mechanisms by which microtubules control FA turnover in migrating cells are beginning to emerge.

scholarly journals Zyxin Is Involved in Fibroblast Rigidity Sensing and Durotaxis

2021 ◽  
Vol 9 ◽  
Author(s):  
Ai Kia Yip ◽  
Songjing Zhang ◽  
Lor Huai Chong ◽  
Elsie Cheruba ◽  
Jessie Yong Xing Woon ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Cell Migration ◽  
Actin Cytoskeleton ◽  
Focal Adhesions ◽  
Wild Type ◽  
Actin Organization ◽  
Rigidity Sensing ◽  
Substrate Rigidity ◽  
Cell Traction ◽  
Traction Stress

Focal adhesions (FAs) are specialized structures that enable cells to sense their extracellular matrix rigidity and transmit these signals to the interior of the cells, bringing about actin cytoskeleton reorganization, FA maturation, and cell migration. It is known that cells migrate towards regions of higher substrate rigidity, a phenomenon known as durotaxis. However, the underlying molecular mechanism of durotaxis and how different proteins in the FA are involved remain unclear. Zyxin is a component of the FA that has been implicated in connecting the actin cytoskeleton to the FA. We have found that knocking down zyxin impaired NIH3T3 fibroblast’s ability to sense and respond to changes in extracellular matrix in terms of their FA sizes, cell traction stress magnitudes and F-actin organization. Cell migration speed of zyxin knockdown fibroblasts was also independent of the underlying substrate rigidity, unlike wild type fibroblasts which migrated fastest at an intermediate substrate rigidity of 14 kPa. Wild type fibroblasts exhibited durotaxis by migrating toward regions of increasing substrate rigidity on polyacrylamide gels with substrate rigidity gradient, while zyxin knockdown fibroblasts did not exhibit durotaxis. Therefore, we propose zyxin as an essential protein that is required for rigidity sensing and durotaxis through modulating FA sizes, cell traction stress and F-actin organization.

Transient mechanical interactions between cells and viscoelastic extracellular matrix

Soft Matter ◽  
2021 ◽  
Author(s):  
Brandon Matthew Slater ◽  
Jing Li ◽  
Dhiraj Indana ◽  
Yihao Xie ◽  
Ovijit Chaudhuri ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Wound Healing ◽  
Cell Migration ◽  
Actin Cytoskeleton ◽  
Physiological Processes ◽  
Contractile Forces ◽  
Surrounding Extracellular Matrix

During various physiological processes, such as wound healing and cell migration, cells continuously interact mechanically with a surrounding extracellular matrix (ECM). Contractile forces generated by the actin cytoskeleton are transmitted...

Neutrophil migration through in vitro interstitial matrix

1992 ◽  
Vol 50 (1) ◽  
pp. 894-895
Author(s):  
J. Roemer ◽  
S.R. Simon
Keyword(s):  
Extracellular Matrix ◽  
Smooth Muscle ◽  
Cell Migration ◽  
Smooth Muscle Cells ◽  
Inflammatory Cell ◽  
Neutrophil Migration ◽  
Culture Conditions ◽  
Aortic Smooth Muscle ◽  
Specific Culture

We are developing an in vitro interstitial extracellular matrix (ECM) system for study of inflammatory cell migration. Falcon brand Cyclopore membrane inserts of various pore sizes are used as a support substrate for production of ECM by R22 rat aortic smooth muscle cells. Under specific culture conditions these cells produce a highly insoluble matrix consisting of typical interstitial ECM components, i.e.: types I and III collagen, elastin, proteoglycans and fibronectin.

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