scholarly journals Cell morphology and focal adhesion location alters internal cell stress

2014 ◽  
Vol 11 (101) ◽  
pp. 20140885 ◽  
Author(s):  
C. A. Mullen ◽  
T. J. Vaughan ◽  
M. C. Voisin ◽  
M. A. Brennan ◽  
P. Layrolle ◽  
...  
Keyword(s):  
Focal Adhesion ◽  
Cell Morphology ◽  
Computational Models ◽  
Substrate Stiffness ◽  
Osteogenic Cell ◽  
Cell Behaviour ◽  
Internal Cell ◽  
Adhesion Sites ◽  
Cell Processes

Extracellular mechanical cues have been shown to have a profound effect on osteogenic cell behaviour. However, it is not known precisely how these cues alter intracellular mechanics to initiate changes in cell behaviour. In this study, a combination of in vitro culture of MC3T3-E1 cells and finite-element modelling was used to investigate the effects of passive differences in substrate stiffness on intracellular mechanics. Cells on collagen-based substrates were classified based on the presence of cell processes and the dimensions of various cellular features were quantified. Focal adhesion (FA) density was quantified from immunohistochemical staining, while cell and substrate stiffnesses were measured using a live-cell atomic force microscope. Computational models of cell morphologies were developed using an applied contraction of the cell body to simulate active cell contraction. The results showed that FA density is directly related to cell morphology, while the effect of substrate stiffness on internal cell tension was modulated by both cell morphology and FA density, as investigated by varying the number of adhesion sites present in each morphological model. We propose that the cells desire to achieve a homeostatic stress state may play a role in osteogenic cell differentiation in response to extracellular mechanical cues.

scholarly journals Enhanced Piezoelectric Fibered Extracellular Matrix to Promote Cardiomyocyte Maturation and Tissue Formation: A 3D Computational Model

Biology ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 135
Author(s):  
Pau Urdeitx ◽  
Mohamed H. Doweidar
Keyword(s):  
Extracellular Matrix ◽  
Cell Migration ◽  
Computational Models ◽  
Cell Junctions ◽  
Tissue Formation ◽  
Cardiac Muscle Cells ◽  
Cell Processes ◽  
Electrical Stimuli ◽  
Cell Cell

Mechanical and electrical stimuli play a key role in tissue formation, guiding cell processes such as cell migration, differentiation, maturation, and apoptosis. Monitoring and controlling these stimuli on in vitro experiments is not straightforward due to the coupling of these different stimuli. In addition, active and reciprocal cell–cell and cell–extracellular matrix interactions are essential to be considered during formation of complex tissue such as myocardial tissue. In this sense, computational models can offer new perspectives and key information on the cell microenvironment. Thus, we present a new computational 3D model, based on the Finite Element Method, where a complex extracellular matrix with piezoelectric properties interacts with cardiac muscle cells during the first steps of tissue formation. This model includes collective behavior and cell processes such as cell migration, maturation, differentiation, proliferation, and apoptosis. The model has employed to study the initial stages of in vitro cardiac aggregate formation, considering cell–cell junctions, under different extracellular matrix configurations. Three different cases have been purposed to evaluate cell behavior in fibered, mechanically stimulated fibered, and mechanically stimulated piezoelectric fibered extra-cellular matrix. In this last case, the cells are guided by the coupling of mechanical and electrical stimuli. Accordingly, the obtained results show the formation of more elongated groups and enhancement in cell proliferation.

scholarly journals Caspase-mediated Cleavage of p130cas in Etoposide-induced Apoptotic Rat-1 Cells

2000 ◽  
Vol 11 (3) ◽  
pp. 929-939 ◽  
Author(s):  
Seunghyi Kook ◽  
Sang Ryeol Shim ◽  
Soo Jeon Choi ◽  
Joohong Ahnn ◽  
Jae Il Kim ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Focal Adhesion ◽  
Caspase 3 ◽  
Morphological Changes ◽  
Point Mutations ◽  
Membrane Blebbing ◽  
Adhesion Sites ◽  
Focal Adhesion Proteins ◽  
Induced Apoptosis

Apoptosis causes characteristic morphological changes in cells, including membrane blebbing, cell detachment from the extracellular matrix, and loss of cell–cell contacts. We investigated the changes in focal adhesion proteins during etoposide-induced apoptosis in Rat-1 cells and found that during apoptosis, p130cas (Crk-associated substrate [Cas]) is cleaved by caspase-3. Sequence analysis showed that Cas contains 10 DXXD consensus sites preferred by caspase-3. We identified two of these sites (DVPD416G and DSPD748G) in vitro, and point mutations substituting the Asp of DVPD416G and DSPD748G with Glu blocked caspase-3-mediated cleavage. Cleavage at DVPD416G generated a 74-kDa fragment, which was in turn cleaved at DSPD748G, yielding 47- and 31-kDa fragments. Immunofluorescence microscopy revealed well-developed focal adhesion sites in control cells that dramatically declined in number in etoposide-treated cells. Cas cleavage correlated temporally with the onset of apoptosis and coincided with the loss of p125FAK (focal adhesion kinase [FAK]) from focal adhesion sites and the attenuation of Cas–paxillin interactions. Considering that Cas associates with FAK, paxillin, and other molecules involved in the integrin signaling pathway, these results suggest that caspase-mediated cleavage of Cas contributes to the disassembly of focal adhesion complexes and interrupts survival signals from the extracellular matrix.

A Mechanistic Motor-Clutch Model That Explains Cell Shape Dynamics to Cyclic Stretch

2022 ◽  
Author(s):  
Benjamin W. Scandling ◽  
Jia Gou ◽  
Jessica Thomas ◽  
Jacqueline Xuan ◽  
Chuan Xue ◽  
...  
Keyword(s):  
Computational Model ◽  
Computational Models ◽  
The Body ◽  
Cyclic Stretch ◽  
Substrate Stiffness ◽  
Cell Alignment ◽  
Cellular Mechanisms ◽  
Actin Bundles ◽  
The Impact

Many cells in the body experience cyclic mechanical loading, which can impact cellular processes and morphology. In vitro studies often report that cells reorient in response to cyclic stretch of their substrate. To explore cellular mechanisms involved in this reorientation, a computational model was developed by utilizing the previous computational models of the actin-myosin-integrin motor-clutch system developed by others. The computational model predicts that under most conditions, actin bundles align perpendicular to the direction of applied cyclic stretch, but under specific conditions, such as low substrate stiffness, actin bundles align parallel to the direction of stretch. The model also predicts that stretch frequency impacts the rate of reorientation, and that proper myosin function is critical in the reorientation response. These computational predictions are consistent with reports from the literature and new experimental results presented here. The model suggests that the impact of different stretching conditions (stretch type, amplitude, frequency, substrate stiffness, etc.) on the direction of cell alignment can largely be understood by considering their impact on cell-substrate detachment events, specifically whether detachment occurs during stretching or relaxing of the substrate.

How an Eukaryotic Cell Senses the Substrate Stiffness? An Exploration Using a Finite Element Model With Cytoskeleton Modelled as Tensegrity Structure

2009 ◽  
Author(s):  
Gianluca De Santis ◽  
Federica Boschetti ◽  
Alex B. Lennon ◽  
Patrick J. Prendergast ◽  
Pascal Verdonck ◽  
...  
Keyword(s):  
Focal Adhesion ◽  
Mammalian Cells ◽  
Elastic Moduli ◽  
Element Model ◽  
Eukaryotic Cell ◽  
Substrate Stiffness ◽  
Cytoskeletal Filament ◽  
Cell Processes ◽  
Adhesion Complex

Mammalian cells in vivo are connected to the ECM (or other substrate, SS) or other cells having elastic moduli ranging from 10 to 10000 Pa. Several experimental evidences relate cell processes (e.g. changes of spreading area, cytoskeletal filament assembling, focal adhesion complex (FAC)) to SS stiffness, but how a passive substrate affects these cell processes is still unknown [1,2].

scholarly journals Effects of Substrate Stiffness on Neutrophil Adhesion over L-selectin Coated Endothelial

2019 ◽  
Author(s):  
Claude Guillory ◽  
Alice O. Dufour
Keyword(s):  
Blood Flow ◽  
Computational Models ◽  
Young Modulus ◽  
Substrate Stiffness ◽  
Neutrophil Adhesion ◽  
Biological Processes ◽  
Elastic Surface ◽  
Fundamental Process ◽  
A Cell

AbstractRolling of a cell under a hydrodynamic flow like the blood flow and the mechanism for the adhesion of a cell to the blood vessel is one of the fundamental process in many pathological and biological processes. An important example of these processes is inflammatory response and moving of the leukocytes to the sites of inflammation. While the blood-borne cells travel with the blood flow, they can interact with the inner endothelium’s wall, which is composed of a soft layer of endothelial cells. Not until recently, the effect of endothelial stiffness was poorly understood. Recent in-vitro and computational models, like modified Adhesive Dynamics, have shown that the elasticity of the underlying substrate can alter the rolling and adhesion of a cell. In this study, we investigate the effects of the substrate stiffness on the rolling and adhesion of a cell with neutrophil ligands by using the Adhesive Dynamic simulation. The vessel is modeled as an elastic surface coated with L-selectin molecules, which can form bonds with the ligands. In our simulation, the Young modulus of the surface ranges between 5 to 80 kPa. The results show that the softer substrate helps to capture the cell with neutrophil ligands. These results help us to understand how the state of adhesion changes for the neutrophil adhesion over L-selectin.

scholarly journals Correlating cell morphology and osteoid mineralization relative to strain profile for bone tissue engineering applications

2007 ◽  
Vol 5 (25) ◽  
pp. 899-907 ◽  
Author(s):  
M.A Wood ◽  
Y Yang ◽  
E Baas ◽  
D.O Meredith ◽  
R.G Richards ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Bone Tissue Engineering ◽  
Bone Tissue ◽  
Cell Morphology ◽  
Bone Cells ◽  
Calcium Deposition ◽  
Cell Behaviour ◽  
Local Strains ◽  
Strain Profile ◽  
Pore Model

A number of bone tissue engineering strategies use porous three-dimensional scaffolds in combination with bioreactor regimes. The ability to understand cell behaviour relative to strain profile will allow for the effects of mechanical conditioning in bone tissue engineering to be realized and optimized. We have designed a model system to investigate the effects of strain profile on bone cell behaviour. This simplified model has been designed with a view to providing insight into the types of strain distribution occurring across a single pore of a scaffold subjected to perfusion–compression conditioning. Local strains were calculated at the surface of the pore model using finite-element analysis. Scanning electron microscopy was used in secondary electron mode to identify cell morphology within the pore relative to local strains, while backscattered electron detection in combination with X-ray microanalysis was used to identify calcium deposition. Morphology was altered according to the level of strain experienced by bone cells, where cells subjected to compressive strains (up to 0.61%) appeared extremely rounded while those experiencing zero and tensile strain (up to 0.81%) were well spread. Osteoid mineralization was similarly shown to be dose dependent with respect to substrate strain within the pore model, with the highest level of calcium deposition identified in the intermediate zones of tension/compression.

scholarly journals The extracellular-regulated protein kinase 5 (ERK5) enhances metastatic burden in triple-negative breast cancer through focal adhesion protein kinase (FAK)-mediated regulation of cell adhesion

Oncogene ◽  
2021 ◽  
Author(s):  
Qiuping Xu ◽  
Jingwei Zhang ◽  
Brian A. Telfer ◽  
Hao Zhang ◽  
Nisha Ali ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Protein Kinase ◽  
Tumor Growth ◽  
Focal Adhesion ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
Metastatic Breast ◽  
Adhesion Protein ◽  
Focal Adhesion Protein

AbstractThere is overwhelming clinical evidence that the extracellular-regulated protein kinase 5 (ERK5) is significantly dysregulated in human breast cancer. However, there is no definite understanding of the requirement of ERK5 in tumor growth and metastasis due to very limited characterization of the pathway in disease models. In this study, we report that a high level of ERK5 is a predictive marker of metastatic breast cancer. Mechanistically, our in vitro data revealed that ERK5 was critical for maintaining the invasive capability of triple-negative breast cancer (TNBC) cells through focal adhesion protein kinase (FAK) activation. Specifically, we found that phosphorylation of FAK at Tyr397 was controlled by a kinase-independent function of ERK5. Accordingly, silencing ERK5 in mammary tumor grafts impaired FAK phosphorylation at Tyr397 and suppressed TNBC cell metastasis to the lung without preventing tumor growth. Collectively, these results establish a functional relationship between ERK5 and FAK signaling in promoting malignancy. Thus, targeting the oncogenic ERK5-FAK axis represents a promising therapeutic strategy for breast cancer exhibiting aggressive clinical behavior.

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