Molecular clutch drives cell response to surface viscosity

Cell response to matrix rigidity has been explained by the mechanical properties of the actin-talin-integrin-fibronectin clutch. Here the molecular clutch model is extended to account for cell interactions with purely viscous surfaces (i.e., without an elastic component). Supported lipid bilayers present an idealized and controllable system through which to study this concept. Using lipids of different diffusion coefficients, the mobility (i.e., surface viscosity) of the presented ligands (in this case RGD) was altered by an order of magnitude. Cell size and cytoskeletal organization were proportional to viscosity. Furthermore, there was a higher number of focal adhesions and a higher phosphorylation of FAK on less-mobile (more-viscous) surfaces. Actin retrograde flow, an indicator of the force exerted on surfaces, was also seen to be faster on more mobile surfaces. This has consequential effects on downstream molecules; the mechanosensitive YAP protein localized to the nucleus more on less-mobile (more-viscous) surfaces and differentiation of myoblast cells was enhanced on higher viscosity. This behavior was explained within the framework of the molecular clutch model, with lower viscosity leading to a low force loading rate, preventing the exposure of mechanosensitive proteins, and with a higher viscosity causing a higher force loading rate exposing these sites, activating downstream pathways. Consequently, the understanding of how viscosity (regardless of matrix stiffness) influences cell response adds a further tool to engineer materials that control cell behavior.

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Does cellular adaptation to force loading rate determine the biphasic vs monotonic response of actin retrograde flow with substrate rigidity?

10.1101/2021.04.23.441062 ◽

2021 ◽

Author(s):

Partho Sakha De ◽

Rumi De

Keyword(s):

Cancer Progression ◽

Loading Rate ◽

Focal Adhesions ◽

Traction Force ◽

Leading Edge ◽

Substrate Stiffness ◽

Retrograde Flow ◽

Force Loading ◽

Substrate Rigidity ◽

Cell Traction

AbstractThe transmission of cytoskeletal forces to the extracellular matrix through focal adhesion complexes is essential for a multitude of biological processes such as cell migration, differentiation, tissue development, cancer progression, among others. During migration, focal adhesions arrest the actin retrograde flow towards the cell interior, allowing the cell front to move forward. Here, we address a puzzling observation of the existence of two distinct phenomena: a biphasic relationship of the retrograde flow and cell traction force with increasing substrate rigidity, with maximum traction force and minimum retrograde flow velocity being present at an optimal substrate stiffness; in contrast, a monotonic relationship between them where the retrograde flow decreases and traction force increases with substrate stiffness. We propose a theoretical model for cell-matrix adhesions at the leading edge of a migrating cell, incorporating a novel approach in force loading rate sensitive binding and reinforcement of focal adhesions assembly and the subsequent force-induced slowing down of actin flow. Our model unravels both biphasic and monotonic responses of the retrograde flow and cell traction force with increasing substrate rigidity, owing to the cell’s ability to sense and adapt to the fast-growing forces. Moreover, we also elucidate how the viscoelastic properties of the substrate regulate these nonlinear responses and alter cellular behaviours.

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Dynamic localization of αB-crystallin at the microtubule cytoskeleton network in beating heart cells

The Journal of Biochemistry ◽

10.1093/jb/mvaa025 ◽

2020 ◽

Vol 168 (2) ◽

pp. 125-137 ◽

Cited By ~ 2

Author(s):

Eri Ohto-Fujita ◽

Saaya Hayasaki ◽

Aya Atomi ◽

Soichiro Fujiki ◽

Toshiyuki Watanabe ◽

...

Keyword(s):

Cultured Cells ◽

Resonance Energy Transfer ◽

Focal Adhesions ◽

Resonance Energy ◽

Heart Cells ◽

Striated Muscles ◽

Slow Skeletal Muscle ◽

Αb Crystallin ◽

Cardiac Muscles ◽

Myoblast Cells

Abstract αB-crystallin is highly expressed in the heart and slow skeletal muscle; however, the roles of αB-crystallin in the muscle are obscure. Previously, we showed that αB-crystallin localizes at the sarcomere Z-bands, corresponding to the focal adhesions of cultured cells. In myoblast cells, αB-crystallin completely colocalizes with microtubules and maintains cell shape and adhesion. In this study, we show that in beating cardiomyocytes α-tubulin and αB-crystallin colocalize at the I- and Z-bands of the myocardium, where it may function as a molecular chaperone for tubulin/microtubules. Fluorescence recovery after photobleaching (FRAP) analysis revealed that the striated patterns of GFP-αB-crystallin fluorescence recovered quickly at 37°C. FRAP mobility assay also showed αB-crystallin to be associated with nocodazole-treated free tubulin dimers but not with taxol-treated microtubules. The interaction of αB-crystallin and free tubulin was further confirmed by immunoprecipitation and microtubule sedimentation assay in the presence of 1–100 μM calcium, which destabilizes microtubules. Förster resonance energy transfer analysis showed that αB-crystallin and tubulin were at 1–10 nm apart from each other in the presence of colchicine. These results suggested that αB-crystallin may play an essential role in microtubule dynamics by maintaining free tubulin in striated muscles, such as the soleus or cardiac muscles.

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Alignment of Carbon Nanotubes: An Approach to Modulate Cell Orientation and Asymmetry

Nano LIFE ◽

10.1142/s1793984414500020 ◽

2014 ◽

Vol 04 (01) ◽

pp. 1450002 ◽

Cited By ~ 1

Author(s):

Qingsu Cheng ◽

Greg M. Harris ◽

Marc-Olivier Blais ◽

Katy Rutledge ◽

Ehsan Jabbarzadeh

Keyword(s):

Stem Cells ◽

Control Cell ◽

Adhesion Formation ◽

Embryonic Stem ◽

Focal Adhesions ◽

Biological Tissues ◽

Spatiotemporal Pattern ◽

Cell Alignment ◽

Cell Orientation

Stem cells offer a promising tool in tissue engineering strategies, as their differentiated derivatives can be used to reconstruct most biological tissues. These approaches rely on controlling the biophysical cues that tune the ultimate fate of cells. In this context, significant effort has gone to parse out the role of conflicting matrix-elicited signals (e.g., topography and elasticity) in regulation of macroscopic characteristics of cells (e.g., shape and polarity). A critical hurdle, however, lies in our inability to recapitulate the nanoscale spatiotemporal pattern of these signals. The study presented in this manuscript took an initial step to overcome this challenge by developing a carbon nanotube (CNT)-based substrate for nanoresolution control of focal adhesion formation and cell alignment. The utility of this system was studied using human umbilical vascular endothelial cells (HUVECs) and human embryonic stem cells (hESCs) at a single cell level. Our results demonstrated the ability to control cell orientation by merely controlling the alignment of focal adhesions at a nanoscale size. Our long-term vision is to use these nanoengineered substrates to mimic cell orientation in earlier development and explore the role of polarity in asymmetric division and lineage specification of dividing cells.

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Association between increase in vertical ground reaction force loading rate and pain level in women with patellofemoral pain after a patellofemoral joint loading protocol

The Knee ◽

10.1016/j.knee.2018.03.009 ◽

2018 ◽

Vol 25 (3) ◽

pp. 398-405 ◽

Cited By ~ 8

Author(s):

Ronaldo Valdir Briani ◽

Marcella Ferraz Pazzinatto ◽

Marina Cabral Waiteman ◽

Danilo de Oliveira Silva ◽

Fábio Mícolis de Azevedo

Keyword(s):

Ground Reaction Force ◽

Patellofemoral Joint ◽

Loading Rate ◽

Reaction Force ◽

Patellofemoral Pain ◽

Pain Level ◽

Joint Loading ◽

Vertical Ground Reaction Force ◽

Force Loading ◽

Vertical Ground

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Focal adhesion kinase protein regulates Wnt3a gene expression to control cell fate specification in the developing neural plate

Molecular Biology of the Cell ◽

10.1091/mbc.e10-12-0932 ◽

2011 ◽

Vol 22 (13) ◽

pp. 2409-2421 ◽

Cited By ~ 24

Author(s):

Yuri Fonar ◽

Yoni E. Gutkovich ◽

Heather Root ◽

Anastasia Malyarova ◽

Emil Aamar ◽

...

Keyword(s):

Gene Expression ◽

Wnt Signaling ◽

Focal Adhesion Kinase ◽

Cell Fate ◽

Focal Adhesion ◽

Control Cell ◽

Focal Adhesions ◽

Neural Plate ◽

Cell Fate Specification ◽

Fate Specification

Focal adhesion kinase (FAK) is a cytoplasmic tyrosine kinase protein localized to regions called focal adhesions, which are contact points between cells and the extracellular matrix. FAK protein acts as a scaffold to transfer adhesion-dependent and growth factor signals into the cell. Increased FAK expression is linked to aggressive metastatic and invasive tumors. However, little is known about its normal embryonic function. FAK protein knockdown during early Xenopus laevis development anteriorizes the embryo. Morphant embryos express increased levels of anterior neural markers, with reciprocally reduced posterior neural marker expression. Posterior neural plate folding and convergence-extension is also inhibited. This anteriorized phenotype resembles that of embryos knocked down zygotically for canonical Wnt signaling. FAK and Wnt3a genes are both expressed in the neural plate, and Wnt3a expression is FAK dependent. Ectopic Wnt expression rescues this FAK morphant anteriorized phenotype. Wnt3a thus acts downstream of FAK to balance anterior–posterior cell fate specification in the developing neural plate. Wnt3a gene expression is also FAK dependent in human breast cancer cells, suggesting that this FAK–Wnt linkage is highly conserved. This unique observation connects the FAK- and Wnt-signaling pathways, both of which act to promote cancer when aberrantly activated in mammalian cells.

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Highly permeable artificial water channels that can self-assemble into two-dimensional arrays

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1508575112 ◽

2015 ◽

Vol 112 (32) ◽

pp. 9810-9815 ◽

Cited By ~ 88

Author(s):

Yue-xiao Shen ◽

Wen Si ◽

Mustafa Erbakan ◽

Karl Decker ◽

Rita De Zorzi ◽

...

Keyword(s):

Lipid Bilayers ◽

Chemical Stability ◽

First Generation ◽

Single Channel ◽

Water Channels ◽

Water Molecules ◽

Permeable Membrane ◽

Osmotic Water ◽

Order Of Magnitude ◽

Artificial Water

Bioinspired artificial water channels aim to combine the high permeability and selectivity of biological aquaporin (AQP) water channels with chemical stability. Here, we carefully characterized a class of artificial water channels, peptide-appended pillar[5]arenes (PAPs). The average single-channel osmotic water permeability for PAPs is 1.0(±0.3) × 10−14 cm3/s or 3.5(±1.0) × 108 water molecules per s, which is in the range of AQPs (3.4∼40.3 × 108 water molecules per s) and their current synthetic analogs, carbon nanotubes (CNTs, 9.0 × 108 water molecules per s). This permeability is an order of magnitude higher than first-generation artificial water channels (20 to ∼107 water molecules per s). Furthermore, within lipid bilayers, PAP channels can self-assemble into 2D arrays. Relevant to permeable membrane design, the pore density of PAP channel arrays (∼2.6 × 105 pores per μm2) is two orders of magnitude higher than that of CNT membranes (0.1∼2.5 × 103 pores per μm2). PAP channels thus combine the advantages of biological channels and CNTs and improve upon them through their relatively simple synthesis, chemical stability, and propensity to form arrays.

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Cell motion as a stochastic process controlled by focal contacts dynamics

10.1101/750331 ◽

2019 ◽

Cited By ~ 1

Author(s):

Simon Lo Vecchio ◽

Raghavan Thiagarajan ◽

David Caballero ◽

Vincent Vigon ◽

Laurent Navoret ◽

...

Keyword(s):

Control Cell ◽

Focal Adhesions ◽

Contact Dynamics ◽

Driving Mechanism ◽

Focal Contact ◽

Focal Contacts ◽

Consistent Model ◽

Cell Motion

SUMMARYDirected cell motion is essential in physiological and pathological processes such as morphogenesis, wound healing and cancer spreading. Chemotaxis has often been proposed as the driving mechanism, even though evidence of long-range gradients is often lacking in vivo. By patterning adhesive regions in space, we control cell shape and the associated potential to move along one direction in another mode of migration coined ratchetaxis. We report that focal contacts distributions collectively dictate cell directionality, and bias is non-linearly increased by gap distance between adhesive regions. Focal contact dynamics on micro-patterns allow to integrate these phenomena in a consistent model where each focal contact can be translated into a force with known amplitude and direction, leading to quantitative predictions for cell motion in every condition. Altogether, our study shows how local and minutes timescale dynamics of focal adhesions and their distribution lead to long term cellular motion with simple geometric rules.

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Distinct phospho-forms of cortactin differentially regulate actin polymerization and focal adhesions

AJP Cell Physiology ◽

10.1152/ajpcell.00238.2008 ◽

2008 ◽

Vol 295 (5) ◽

pp. C1113-C1122 ◽

Cited By ~ 37

Author(s):

Anne E. Kruchten ◽

Eugene W. Krueger ◽

Yu Wang ◽

Mark A. McNiven

Keyword(s):

Cell Migration ◽

Focal Adhesion ◽

Actin Polymerization ◽

Control Cell ◽

Focal Adhesions ◽

Serine Phosphorylation ◽

Actin Binding ◽

Actin Assembly

Cortactin is an actin-binding protein that is overexpressed in many cancers and is a substrate for both tyrosine and serine/threonine kinases. Tyrosine phosphorylation of cortactin has been observed to increase cell motility and invasion in vivo, although it has been reported to have both positive and negative effects on actin polymerization in vitro. In contrast, serine phosphorylation of cortactin has been shown to stimulate actin assembly in vitro. Currently, the effects of cortactin serine phosphorylation on cell migration are unclear, and furthermore, how the distinct phospho-forms of cortactin may differentially contribute to cell migration has not been directly compared. Therefore, we tested the effects of different tyrosine and serine phospho-mutants of cortactin on lamellipodial protrusion, actin assembly within cells, and focal adhesion dynamics. Interestingly, while expression of either tyrosine or serine phospho-mimetic cortactin mutants resulted in increased lamellipodial protrusion and cell migration, these effects appeared to be via distinct processes. Cortactin mutants mimicking serine phosphorylation appeared to predominantly affect actin polymerization, whereas mutation of cortactin tyrosine residues resulted in alterations in focal adhesion turnover. Thus these findings provide novel insights into how distinct phospho-forms of cortactin may differentially contribute to actin and focal adhesion dynamics to control cell migration.

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Human foetal osteoblastic cell response to polymer-demixed nanotopographic interfaces

Journal of The Royal Society Interface ◽

10.1098/rsif.2004.0019 ◽

2005 ◽

Vol 2 (2) ◽

pp. 97-108 ◽

Cited By ~ 127

Author(s):

Jung Yul Lim ◽

Joshua C Hansen ◽

Christopher A Siedlecki ◽

James Runt ◽

Henry J Donahue

Keyword(s):

Cell Response ◽

Cell Function ◽

Early Stage ◽

Control Cell ◽

Bone Cell ◽

Cell Phenotype ◽

Osteoblastic Cell ◽

Bone Cell Differentiation ◽

Biomaterial Interfaces ◽

Cells Cultured

Nanoscale cell–substratum interactions are of significant interest in various biomedical applications. We investigated human foetal osteoblastic cell response to randomly distributed nanoisland topography with varying heights (11, 38 and 85 nm) produced by a polystyrene (PS)/polybromostyrene polymer-demixing technique. Cells displayed island-conforming lamellipodia spreading, and filopodia projections appeared to play a role in sensing the nanotopography. Cells cultured on 11 nm high islands displayed significantly enhanced cell spreading and larger cell dimensions than cells on larger nanoislands or flat PS control, on which cells often displayed a stellate shape. Development of signal transmitting structures such as focal adhesive vinculin protein and cytoskeletal actin stress fibres was more pronounced, as was their colocalization, in cells cultured on smaller nanoisland surfaces. Cell adhesion and proliferation were greater with decreasing island height. Alkaline phosphatase (AP) activity, an early stage marker of bone cell differentiation, also exhibited nanotopography dependence, i.e. higher AP activity on 11 nm islands compared with that on larger islands or flat PS. Therefore, randomly distributed island topography with varying nanoscale heights not only affect adhesion-related cell behaviour but also bone cell phenotype. Our results suggest that modulation of nanoscale topography may be exploited to control cell function at cell–biomaterial interfaces.

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