-
Journal of Cell Science Sep 2015The focal adhesion protein vinculin connects the actin cytoskeleton, through talin and integrins, with the extracellular matrix. Vinculin consists of a globular head and...
The focal adhesion protein vinculin connects the actin cytoskeleton, through talin and integrins, with the extracellular matrix. Vinculin consists of a globular head and tail domain, which undergo conformational changes from a closed auto-inhibited conformation in the cytoplasm to an open conformation in focal adhesions. Src-mediated phosphorylation has been suggested to regulate this conformational switch. To explore the role of phosphorylation in vinculin activation, we used knock-out mouse embryonic fibroblasts re-expressing different vinculin mutants in traction microscopy, magnetic tweezer microrheology, FRAP and actin-binding assays. Compared to cells expressing wild-type or constitutively active vinculin, we found reduced tractions, cytoskeletal stiffness, adhesion strength, and increased vinculin dynamics in cells expressing constitutively inactive vinculin or vinculin where Src-mediated phosphorylation was blocked by replacing tyrosine at position 100 and/or 1065 with a non-phosphorylatable phenylalanine residue. Replacing tyrosine residues with phospho-mimicking glutamic acid residues restored cellular tractions, stiffness and adhesion strength, as well as vinculin dynamics, and facilitated vinculin-actin binding. These data demonstrate that Src-mediated phosphorylation is necessary for vinculin activation, and that phosphorylation controls cytoskeletal mechanics by regulating force transmission between the actin cytoskeleton and focal adhesion proteins.
Topics: Animals; Cell Adhesion; Cytoskeleton; Energy Transfer; Fibroblasts; Integrins; Mice; Mice, Knockout; Phosphorylation; Point Mutation; Protein Structure, Secondary; Vinculin; src-Family Kinases
PubMed: 26240176
DOI: 10.1242/jcs.172031 -
Experimental Eye Research Apr 2019Epithelial wound healing is essential for maintaining the function and clarity of the cornea. Successful repair after injury involves the coordinated movements of cell...
Epithelial wound healing is essential for maintaining the function and clarity of the cornea. Successful repair after injury involves the coordinated movements of cell sheets over the wounded region. While collective migration has been the focus of studies, the effects that environmental changes have on this form of movement are poorly understood. To examine the role of substrate compliancy on multi-layered epithelial sheet migration, we performed traction force and confocal microscopy to determine differences in traction forces and to examine focal adhesions on synthetic and biological substrates. The leading edges of corneal epithelial sheets undergo retraction or contraction prior to migration, and alterations in the sheet's stiffness are affected by the amount of force exerted by cells at the leading edge. On substrates of 30 kPa, cells exhibited greater and more rapid movement than on substrates of 8 kPa, which are similar to that of the corneal basement membrane. Vinculin and its phosphorylated residue Y1065 were prominent along the basal surface of migrating cells, while Y822 was prominent between neighboring cells along the leading edge. Vinculin localization was diffuse on a substrate where the basement membrane was removed. Furthermore, when cells were cultured on fibronectin-coated acrylamide substrates of 8 and 50 kPa and then wounded, there was an injury-induced phosphorylation of Y1065 and substrate dependent changes in the number and size of vinculin containing focal adhesions. These results demonstrate that changes in substrate stiffness affected traction forces and vinculin dynamics, which potentially could contribute to the delayed healing response associated with certain corneal pathologies.
Topics: Analysis of Variance; Biomechanical Phenomena; Cell Adhesion; Cell Movement; Cornea; Epithelial Cells; Epithelium; Humans; Limbus Corneae; Phosphorylation; Vinculin
PubMed: 30653966
DOI: 10.1016/j.exer.2019.01.014 -
PLoS Computational Biology Oct 2023Cells interact with the extracellular matrix (ECM) via cell-ECM adhesions. These physical interactions are transduced into biochemical signals inside the cell which...
Cells interact with the extracellular matrix (ECM) via cell-ECM adhesions. These physical interactions are transduced into biochemical signals inside the cell which influence cell behaviour. Although cell-ECM interactions have been studied extensively, it is not completely understood how immature (nascent) adhesions develop into mature (focal) adhesions and how mechanical forces influence this process. Given the small size, dynamic nature and short lifetimes of nascent adhesions, studying them using conventional microscopic and experimental techniques is challenging. Computational modelling provides a valuable resource for simulating and exploring various "what if?" scenarios in silico and identifying key molecular components and mechanisms for further investigation. Here, we present a simplified mechano-chemical model based on ordinary differential equations with three major proteins involved in adhesions: integrins, talin and vinculin. Additionally, we incorporate a hypothetical signal molecule that influences adhesion (dis)assembly rates. We find that assembly and disassembly rates need to vary dynamically to limit maturation of nascent adhesions. The model predicts biphasic variation of actin retrograde velocity and maturation fraction with substrate stiffness, with maturation fractions between 18-35%, optimal stiffness of ∼1 pN/nm, and a mechanosensitive range of 1-100 pN/nm, all corresponding to key experimental findings. Sensitivity analyses show robustness of outcomes to small changes in parameter values, allowing model tuning to reflect specific cell types and signaling cascades. The model proposes that signal-dependent disassembly rate variations play an underappreciated role in maturation fraction regulation, which should be investigated further. We also provide predictions on the changes in traction force generation under increased/decreased vinculin concentrations, complementing previous vinculin overexpression/knockout experiments in different cell types. In summary, this work proposes a model framework to robustly simulate the mechanochemical processes underlying adhesion maturation and maintenance, thereby enhancing our fundamental knowledge of cell-ECM interactions.
Topics: Focal Adhesions; Vinculin; Actins; Integrins; Extracellular Matrix; Cell Adhesion; Talin
PubMed: 37801464
DOI: 10.1371/journal.pcbi.1011500 -
Histochemistry and Cell Biology Oct 2022Ongoing liver injury leads to fibrosis and ultimately cirrhosis, a leading cause of death worldwide. The primary mechanism underlying the fibrogenic response is the...
Ongoing liver injury leads to fibrosis and ultimately cirrhosis, a leading cause of death worldwide. The primary mechanism underlying the fibrogenic response is the activation of cells known as hepatic stellate cells (HSCs) which are "quiescent" in the normal liver but become "activated" after injury by transdifferentiating into extracellular matrix-secreting myofibroblasts. Since integrins (extracellular matrix binding receptors) are important mediators of HSC activation and fibrogenesis, we hypothesized that focal adhesion (FA) proteins, which link integrins to the intracellular protein machinery, may be important in the activation process. Therefore, using both an in vitro model of activation in primary rat HSCs and an in vivo model of liver injury, we examined three FA proteins: vinculin, FAK, and talin. All three proteins were significantly upregulated during HSC activation at both the messenger RNA (mRNA) and protein levels. Confocal microscopy demonstrated that the proteins had a widespread expression throughout HSCs with prominent localization at the end of actin filaments. Finally, we stimulated HSCs with the profibrotic ligands endothelin-1 (ET-1) and transforming growth factor beta (TGF-β) and observed an increase in the size of vinculin-containing FAs and the cell area occupied by them. The data indicate that HSCs possess a broad array of FA proteins, and given their upregulation during activation, this raises the possibility that they play a role in the fibrogenic response to injury.
Topics: Animals; Cells, Cultured; Endothelin-1; Focal Adhesions; Hepatic Stellate Cells; Integrins; Ligands; Liver; RNA, Messenger; Rats; Rodentia; Talin; Transforming Growth Factor beta; Vinculin
PubMed: 35960334
DOI: 10.1007/s00418-022-02123-y -
International Journal of Molecular... Sep 2022The TGF-β signaling pathway is involved in numerous cellular processes, and its deregulation may result in cancer development. One of the key processes in tumor...
The TGF-β signaling pathway is involved in numerous cellular processes, and its deregulation may result in cancer development. One of the key processes in tumor progression and metastasis is epithelial to mesenchymal transition (EMT), in which TGF-β signaling plays important roles. Recently, AGR2 was identified as a crucial component of the cellular machinery responsible for maintaining the epithelial phenotype, thereby interfering with the induction of mesenchymal phenotype cells by TGF-β effects in cancer. Here, we performed transcriptomic profiling of A549 lung cancer cells with CRISPR-Cas9 mediated knockout with and without TGF-β treatment. We identified significant changes in transcripts associated with focal adhesion and eicosanoid production, in particular arachidonic acid metabolism. Changes in transcripts associated with the focal adhesion pathway were validated by RT-qPCR of , , , , , and mRNAs. In addition, immunofluorescence showed the formation of stress fibers and vinculin foci in cells without AGR2 and in response to TGF-β treatment, with synergistic effects observed. These findings imply that both AGR2 downregulation and TGF-β have a role in focal adhesion formation and cancer cell migration and invasion. Transcripts associated with arachidonic acid metabolism were downregulated after both knockout and TGF-β treatment and were validated by RT-qPCR of , , and . Since PGE is a product of arachidonic acid metabolism, its lowered concentration in media from -knockout cells was confirmed by ELISA. Together, our results demonstrate that AGR2 downregulation and TGF-β have an essential role in focal adhesion formation; moreover, we have identified AGR2 as an important component of the arachidonic acid metabolic pathway.
Topics: Arachidonic Acid; Cell Line, Tumor; Cell Movement; Cyclooxygenase 2; Epithelial-Mesenchymal Transition; Gene Expression Regulation, Neoplastic; Prostaglandins E; Transforming Growth Factor beta; Vinculin
PubMed: 36142758
DOI: 10.3390/ijms231810845 -
The Journal of Cell Biology Jan 2020Talin, vinculin, and paxillin are core components of the dynamic link between integrins and actomyosin. Here, we study the mechanisms that mediate their activation and...
Talin, vinculin, and paxillin are core components of the dynamic link between integrins and actomyosin. Here, we study the mechanisms that mediate their activation and association using a mitochondrial-targeting assay, structure-based mutants, and advanced microscopy. As expected, full-length vinculin and talin are autoinhibited and do not interact with each other. However, contrary to previous models that propose a critical role for forces driving talin-vinculin association, our data show that force-independent relief of autoinhibition is sufficient to mediate their tight interaction. We also found that paxillin can bind to both talin and vinculin when either is inactive. Further experiments demonstrated that adhesions containing paxillin and vinculin can form without talin following integrin activation. However, these are largely deficient in exerting traction forces to the matrix. Our observations lead to a model whereby paxillin contributes to talin and vinculin recruitment into nascent adhesions. Activation of the talin-vinculin axis subsequently leads to the engagement with the traction force machinery and focal adhesion maturation.
Topics: Actin Cytoskeleton; Animals; Cells, Cultured; Fibroblasts; Focal Adhesions; Mice; Mice, Inbred C57BL; Mice, Knockout; Paxillin; Protein Binding; Stress, Mechanical; Talin; Vinculin
PubMed: 31816055
DOI: 10.1083/jcb.201903134 -
Biophysical Journal May 2012Vinculin phosphorylation has been implicated as a potential mechanism for focal adhesion growth and maturation. Four vinculin residues-Y100, S1033, S1045, and Y1065-are...
Vinculin phosphorylation has been implicated as a potential mechanism for focal adhesion growth and maturation. Four vinculin residues-Y100, S1033, S1045, and Y1065-are phosphorylated by kinases during focal adhesion maturation. In this study, phosphorylation at each of these residues is simulated using molecular dynamics models. The simulations demonstrate that once each phosphorylated vinculin structure is at equilibrium, significant local conformational changes result that may impact either vinculin activation or vinculin binding to actin and PIP2. Simulation of vinculin activation after phosphorylation shows that the added phosphoryl groups can prime vinculin for activation. It remains to be seen if vinculin can be phosphorylated at S1033 in vivo, but these simulations highlight that in the event of a S1033 phophorylation vinculin will likely be primed for activation.
Topics: Binding Sites; Computer Simulation; Models, Chemical; Models, Molecular; Phosphorylation; Protein Binding; Protein Conformation; Protein Kinases; Protein Structure, Tertiary; Vinculin
PubMed: 22824265
DOI: 10.1016/j.bpj.2012.01.062 -
Scientific Reports Apr 2019This study utilized a Förster resonance energy transfer (FRET)-based molecular tension sensor and live cell imaging to evaluate the effect of osteocytes, a...
This study utilized a Förster resonance energy transfer (FRET)-based molecular tension sensor and live cell imaging to evaluate the effect of osteocytes, a mechanosensitive bone cell, on the migratory behavior of tumor cells. Two cell lines derived from MDA-MB-231 breast cancer cells were transfected with the vinculin tension sensor to quantitatively evaluate the force in focal adhesions of the tumor cell. Tumor cells treated with MLO-A5 osteocyte-conditioned media (CM) decreased the tensile forces in their focal adhesions and decreased their migratory potential. Tumor cells treated with media derived from MLO-A5 cells exposed to fluid flow-driven shear stress (FFCM) increased the tensile forces and increased migratory potential. Focal adhesion tension in tumor cells was also affected by distance from MLO-A5 cells when the two cells were co-cultured, where tumor cells close to MLO-A5 cells exhibited lower tension and decreased cell motility. Overall, this study demonstrates that focal adhesion tension is involved in altered migratory potential of tumor cells, and tumor-osteocyte interactions decrease the tension and motility of tumor cells.
Topics: Breast Neoplasms; Cell Adhesion; Cell Line, Tumor; Cell Movement; Female; Fluorescence Resonance Energy Transfer; Focal Adhesions; Humans; Neoplasms; Osteoblasts; Osteocytes; Stress, Mechanical; Vinculin
PubMed: 30948840
DOI: 10.1038/s41598-019-42132-x -
Archivum Immunologiae Et Therapiae... Apr 2012The activity of cytoskeletal proteins like talin, vinculin and nestin increases in muscle that regenerates. Little is known about their role or at least their expression...
The activity of cytoskeletal proteins like talin, vinculin and nestin increases in muscle that regenerates. Little is known about their role or at least their expression in the process of regeneration in masticatory muscles of mdx mice, a model of Duchenne muscular dystrophy. To determine a potential role of cytoskeletal proteins in the regeneration process of mdx masticatory muscles, we examined the expression of talin 1, talin 2, vinculin and nestin in 100-day-old control and mdx mice using quantitative RT-PCR, Western blot analyses and histochemistry. The protein expression of talin 1, talin 2, nestin and vinculin in mdx muscles remained unchanged as compared with normal mice. However, in mdx masseter it was found a relative increase of nestin compared to controls. The protein expression of talin 1 and vinculin tended to be increased in mdx tongue and talin 2 to diminish in mdx masseter and temporal muscle. In mdx mice, we found significantly lower percentage of transcripts coding for nestin, talin 1, talin 2 and vinculin in masseter (p < 0.05) and temporal muscle (p < 0.001). In contrast, the mRNA expression of nestin was found to be increased in mdx tongue. Activated satellite cells, myoblasts and immature regenerated muscle fibres in mdx masseter and temporal revealed positive staining for nestin. The findings of the presented work suggest dystrophin-lack-associated changes in the expression of cytoskeletal proteins in mdx masticatory muscles could be compensatory for dystrophin absence. The expression of nestin may serve as an indicator for the regeneration in the orofacial muscles.
Topics: Animals; Cells, Cultured; Disease Models, Animal; Dystrophin; Facial Muscles; Gene Expression Regulation, Developmental; Humans; Intermediate Filament Proteins; Masticatory Muscles; Mice; Mice, Inbred C57BL; Mice, Inbred mdx; Muscular Dystrophy, Duchenne; Mutation; Myoblasts; Nerve Tissue Proteins; Nestin; Regeneration; Satellite Cells, Skeletal Muscle; Talin; Vinculin
PubMed: 22307364
DOI: 10.1007/s00005-012-0167-0 -
Nature Communications Jun 2015Cell-matrix adhesions are central mediators of mechanotransduction, yet the interplay between force and adhesion regulation remains unclear. Here we use live cell...
Cell-matrix adhesions are central mediators of mechanotransduction, yet the interplay between force and adhesion regulation remains unclear. Here we use live cell imaging to map time-dependent cross-correlations between vinculin-mediated tension and adhesion complex area, revealing a plastic, context-dependent relationship. Interestingly, while an expected positive cross-correlation dominated in mid-sized adhesions, small and large adhesions display negative cross-correlation. Furthermore, although large changes in adhesion complex area follow vinculin-mediated tension alterations, small increases in area precede vinculin-mediated tension dynamics. Modelling based on this mapping of the vinculin-mediated tension-adhesion complex area relationship confirms its biological validity, and indicates that this relationship explains adhesion size and lifetime limits, keeping adhesions focal and transient. We also identify a subpopulation of steady-state adhesions whose size and vinculin-mediated tension become stabilized, and whose disassembly may be selectively microtubule-mediated. In conclusion, we define a plastic relationship between vinculin-mediated tension and adhesion complex area that controls fundamental cell-matrix adhesion properties.
Topics: Biomechanical Phenomena; Carcinoma, Non-Small-Cell Lung; Cell Adhesion; Cell Line, Tumor; Fluorescence Resonance Energy Transfer; Fluorescent Dyes; Gene Expression Regulation; Humans; Microtubule-Associated Proteins; Plant Proteins; Time Factors; Vinculin
PubMed: 26109125
DOI: 10.1038/ncomms8524