Cell Shape Control and Related Focal Adheshion Dynamics on Aligned Fiber Networks

2012 ◽  
Author(s):  
Kevin Sheets ◽  
Amrinder Nain
Keyword(s):  
Optical Tweezers ◽  
Shape Control ◽  
Focal Adhesions ◽  
Physical Nature ◽  
Health State ◽  
Cellular Behavior ◽  
Cell Substrate ◽  
A Cell ◽  
Cell Shape Control ◽  
External Stimuli

Cellular elasticity, a measure of a cell’s resistance to changing its shape in response to external stimuli, has been shown in the recent past to be a potential indicator of cell health [1]. A variety of methods including AFM techniques [1, 2], magnetic/optical tweezers [3, 4], and micropillar arrays [6–8] have been used to quantify cellular elasticity to identify cell disease state, including stages of progression in cancerous cells. Since cellular behavior is heavily dependent on the physical nature of the surrounding extracellular matrix (ECM), understanding mechanical cell-substrate interactions may lead to connections between the elasticity of a cell and the cell’s health state [1]. In this study, the STEP (Spinneret-based Tunable Engineered Parameters) technique is used to create suspended nanofibrous polystyrene substrates with tight control on fiber diameter and spacing in single and multiple layers. As cells interact with these various substrates, they take on repeatable configurations and allow the probing of biophysical traits. Specifically, cytoskeletal arrangements provide information on the behavior of the cell nucleus, f-actin stress fibers, and focal adhesions via paxillin staining, which allow for calculation of cellular elasticity.

scholarly journals A contractile and counterbalancing adhesion system controls the 3D shape of crawling cells

2014 ◽  
Vol 205 (1) ◽  
pp. 83-96 ◽  
Author(s):  
Dylan T. Burnette ◽  
Lin Shao ◽  
Carolyn Ott ◽  
Ana M. Pasapera ◽  
Robert S. Fischer ◽  
...  
Keyword(s):  
Cell Shape ◽  
Shape Control ◽  
Three Dimensional ◽  
Focal Adhesions ◽  
Live Cell Microscopy ◽  
Microscopy Data ◽  
Pulling Force ◽  
Cell Shape Control ◽  
Cell Microscopy ◽  
Shape Changes

How adherent and contractile systems coordinate to promote cell shape changes is unclear. Here, we define a counterbalanced adhesion/contraction model for cell shape control. Live-cell microscopy data showed a crucial role for a contractile meshwork at the top of the cell, which is composed of actin arcs and myosin IIA filaments. The contractile actin meshwork is organized like muscle sarcomeres, with repeating myosin II filaments separated by the actin bundling protein α-actinin, and is mechanically coupled to noncontractile dorsal actin fibers that run from top to bottom in the cell. When the meshwork contracts, it pulls the dorsal fibers away from the substrate. This pulling force is counterbalanced by the dorsal fibers’ attachment to focal adhesions, causing the fibers to bend downward and flattening the cell. This model is likely to be relevant for understanding how cells configure themselves to complex surfaces, protrude into tight spaces, and generate three-dimensional forces on the growth substrate under both healthy and diseased conditions.

scholarly journals Microtubules control cellular shape and coherence in amoeboid migrating cells

2019 ◽  
Author(s):  
Aglaja Kopf ◽  
Jörg Renkawitz ◽  
Robert Hauschild ◽  
Irute Girkontaite ◽  
Kerry Tedford ◽  
...  
Keyword(s):  
Cell Shape ◽  
Shape Control ◽  
Complex Geometry ◽  
Control Cell ◽  
Three Dimensional ◽  
Microtubule Organizing Center ◽  
Organizing Center ◽  
A Cell ◽  
Cell Shape Control ◽  
Rate Limit

Cells navigating through tissues face a fundamental challenge: while multiple cellular protrusions explore different paths through the complex geometry of an interstitial matrix the cell needs to avoid becoming too long or ramified, which might ultimately lead to a loss of physical coherence. How a cell surveys its own shape to inform the actomyosin system to retract entangled or stretched protrusions is not understood. Here, we demonstrate that spatially distinct microtubule (MT) dynamics regulate amoeboid cell migration by locally specifying the retraction of explorative protrusions. In migrating dendritic cells (DCs), the microtubule organizing center (MTOC) guides the path through a three dimensional (3D) interstitium and local MT depolymerization in protrusions remote from the MTOC triggers myosin II dependent contractility via the RhoA exchange factor Lfc. Depletion of Lfc leads to aberrant myosin localization, thereby causing two effects that rate-limit locomotion: i) impaired cell edge coordination during path-finding and ii) defective adhesion-resolution. Such compromised cell shape control is particularly hindering when cells navigate through geometrically complex microenvironments, where it leads to entanglement and ultimately fragmentation of the cell body. Our data demonstrate that MTs control cell shape and coherence by locally controlling protrusion-retraction dynamics of the actomyosin system.

scholarly journals Intercellular adhesion stiffness moderates cell decoupling on stiff substrates

2019 ◽  
Author(s):  
D. A. Vargas ◽  
T. Heck ◽  
B. Smeets ◽  
H. Ramon ◽  
H. Parameswaran ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Focal Adhesions ◽  
Substrate Stiffness ◽  
Intercellular Interactions ◽  
Cell Pair ◽  
Patterned Substrate ◽  
Cell Substrate ◽  
A Cell ◽  
Cell Collective ◽  
Cell Cell

AbstractThe interplay between cell-cell and cell-substrate interactions is complex yet necessary for the formation and well-functioning of tissues. The same mechanosensing mechanisms used by the cell to sense its extracellular matrix, also play a role in intercellular interactions. We used the discrete element method to develop a computational model of a deformable cell that includes subcellular components responsible for mechanosensing. We modeled a cell pair in 3D on a patterned substrate, a simple laboratory setup to study intercellular interactions. We explicitly modeled focal adhesions between the cells and the substrate, and adherens junctions between cells. These mechanosensing adhesions matured; their disassembly rate was dictated by the force they carry. We also modeled stress fibers which bind the discrete adhesions and contract. The mechanosensing fibers strengthened upon stalling and exerted higher forces. Traction exerted on the substrate was used to generate maps displaying the magnitude of the tractions along the cell-substrate interface. Simulated traction maps are compared to experimental maps obtained via traction force microscopy. The model recreates the dependence on substrate stiffness of the tractions’ spatial distribution across the cell-substrate interface, the contractile moment of the cell pair, the intercellular force, and the number of focal adhesions. It also recreates the phenomenon of cell decoupling, in which cells exert forces separately when substrate stiffness increases. More importantly, the model provides viable molecular explanations for decoupling. It shows that the implemented mechanosensing mechanisms are responsible for competition between different fiber-adhesion configurations present in the cell pair. The point at which an increasing substrate stiffness becomes as high as that of the cell-cell interface is the tipping point at which configurations that favor cell-substrate adhesion dominate over those favoring cell-cell adhesion. This competition is responsible for decoupling. Additionally, we learn that extent of decoupling is modulated by adherens junction maturation.Statement of SignificanceCells are sensitive to mechanical factors of their extracellular matrix while simultaneously in contact with other cells. This creates complex intercellular interactions that depend on substrate stiffness and play a role in processes such as development and diseases like cardiac arrhythmia, asthma, and cancer. The simplest cell collective system in vitro is a cell pair on a patterned substrate. We developed a computational model of this system which explains the role of molecular adhesions and contractile fibers in the dynamics of cell-cell interactions on substrates with different stiffness. It is one of the first models of a deformable cell collective based on mechanical principles. It recreates cellular decoupling, a phenomenon in which cells exert forces separately, when substrate stiffness increases.

Production and Analysis of High Resolution Polymer Replicas of Fibrillar Collagen

1999 ◽  
Vol 5 (S2) ◽  
pp. 398-399
Author(s):  
P. Sims ◽  
B. Todd ◽  
S. Eppell ◽  
T. Li ◽  
K. Park ◽  
...  
Keyword(s):  
Cellular Response ◽  
Physical Nature ◽  
Cell Types ◽  
Artificial Substrates ◽  
Adherent Cell ◽  
Fibrillar Collagen ◽  
New Materials ◽  
Substrate Interactions ◽  
Number Of Factors ◽  
Cell Substrate

Adherent cells generally construct the immediate substrate upon which they reside. This may occur via synthesis and secretion of new materials and/or by rearrangement and modification of existing substrate. The response of adherent cell types to an existing substrate can be influenced by a number of factors which include both the chemical and physical nature of the substrate. Cell adhesion, proliferation, differentiation and death can all be substrate dependent. Much effort has been directed toward chemical modification of substrates to regulate one or more of the parameters noted above. A significant, but somewhat smaller, degree of attention has been paid to the effects of the topography and microtopography on the cell response to substrate materials. Studies to date strongly suggest the topography is a significant factor in cell-substrate interactions. As noted above, it is most probable that both the chemistry and the structure of a substrate simultaneously influence the cellular response. However we wished to determine, particularly for artificial substrates, the role which microtopography can play in cell-substrate interactions.

Syndesmos, a protein that interacts with the cytoplasmic domain of syndecan-4, mediates cell spreading and actin cytoskeletal organization

2000 ◽  
Vol 113 (2) ◽  
pp. 315-324 ◽  
Author(s):  
P.C. Baciu ◽  
S. Saoncella ◽  
S.H. Lee ◽  
F. Denhez ◽  
D. Leuthardt ◽  
...  
Keyword(s):  
Plasma Membranes ◽  
Focal Adhesions ◽  
Cell Spreading ◽  
Cytoplasmic Domain ◽  
Cellular Protein ◽  
Actin Stress Fiber ◽  
Independent Manner ◽  
Intracellular Proteins ◽  
Central Regions ◽  
A Cell

Syndecan-4 is a cell surface heparan sulfate proteoglycan which, in cooperation with integrins, transduces signals for the assembly of focal adhesions and actin stress fibers in cells plated on fibronectin. The regulation of these cellular events is proposed to occur, in part, through the interaction of the cytoplasmic domains of these transmembrane receptors with intracellular proteins. To identify potential intracellular proteins that interact with the cytoplasmic domain of syndecan-4, we carried out a yeast two-hybrid screen in which the cytoplasmic domain of syndecan-4 was used as bait. As a result of this screen, we have identified a novel cellular protein that interacts with the cytoplasmic domain of syndecan-4 but not with those of the other three syndecan family members. The interaction involves both the membrane proximal and variable central regions of the cytoplasmic domain. We have named this cDNA and encoded protein syndesmos. Syndesmos is ubiquitously expressed and can be myristylated. Consistent with its myristylation and syndecan-4 association, syndesmos colocalizes with syndecan-4 in the ventral plasma membranes of cells plated on fibronectin. When overexpressed in NIH 3T3 cells, syndesmos enhances cell spreading, actin stress fiber and focal contact formation in a serum-independent manner.

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