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Nature Communications Jul 2023The talin-vinculin axis is a key mechanosensing component of cellular focal adhesions. How talin and vinculin respond to forces and regulate one another remains unclear....
The talin-vinculin axis is a key mechanosensing component of cellular focal adhesions. How talin and vinculin respond to forces and regulate one another remains unclear. By combining single-molecule magnetic tweezers experiments, Molecular Dynamics simulations, actin-bundling assays, and adhesion assembly experiments in live cells, we here describe a two-ways allosteric network within vinculin as a regulator of the talin-vinculin interaction. We directly observe a maturation process of vinculin upon talin binding, which reinforces the binding to talin at a rate of 0.03 s. This allosteric transition can compete with force-induced dissociation of vinculin from talin only at forces up to 10 pN. Mimicking the allosteric activation by mutation yields a vinculin molecule that bundles actin and localizes to focal adhesions in a force-independent manner. Hence, the allosteric switch confines talin-vinculin interactions and focal adhesion build-up to intermediate force levels. The 'allosteric vinculin mutant' is a valuable molecular tool to further dissect the mechanical and biochemical signalling circuits at focal adhesions and elsewhere.
Topics: Actins; Talin; Vinculin; Allosteric Regulation; Focal Adhesions; Protein Binding
PubMed: 37463895
DOI: 10.1038/s41467-023-39646-4 -
Journal of Biomedical Optics Aug 2023Forces inside cells play a fundamental role in tissue growth, affecting important processes such as cancer cell migration or tissue repair after injury. Förster...
SIGNIFICANCE
Forces inside cells play a fundamental role in tissue growth, affecting important processes such as cancer cell migration or tissue repair after injury. Förster resonance energy transfer (FRET)-based tension sensors are a remarkable tool for studying these forces and should be made easier to use.
AIM
We prove that absolute FRET efficiency can be measured on a simple setup, an order of magnitude more cost-effective than a standard FRET microscopy setup, by applying it to vinculin tension sensors (VinTS) at the focal adhesions of live CHO-K1 cells.
APPROACH
Our setup located at Université Paris-Saclay acquires donor and acceptor fluorescence in parallel on two low-cost CMOS cameras and uses two LEDs for rapid switching of the excitation wavelength at a reduced cost. The calibration required to extract FRET efficiency was achieved using a single construct (TSMod). FRET efficiencies were measured for VinTS and the tail-less control VinTL, lacking the actin-binding domain of vinculin. Measurements were confirmed on the same cell type using a more standard intensity-based setup located at Rutgers University.
RESULTS
The average FRET efficiency of VinTS () over more than 10,000 focal adhesions is significantly lower () than that of VinTL (), our control that is insensitive to force, in agreement with the force exerted on vinculin at focal adhesions. Attachment of the CHO-K1 cells on fibronectin decreases FRET efficiency, thus increasing the force, compared with poly-lysine. FRET efficiency for the VinTL control is consistent with all measurements currently available in the literature, confirming the validity of our measurements and hence of our simpler setup.
CONCLUSIONS
Force measurements, resolved spatially inside a cell, can be achieved using FRET-based tension sensors with a cost effective intensity-based setup. This will facilitate combining FRET with techniques for applying controlled forces such as optical tweezers.
Topics: Humans; Fluorescence Resonance Energy Transfer; Focal Adhesions; Vinculin; Cost-Benefit Analysis; Mechanical Phenomena
PubMed: 37441563
DOI: 10.1117/1.JBO.28.8.082808 -
Journal of Proteome Research Aug 2023Local vibration can induce vascular injuries, one example is the hand-arm vibration syndrome (HAVS) caused by hand-transmitted vibration (HTV). Little is known about the...
Local vibration can induce vascular injuries, one example is the hand-arm vibration syndrome (HAVS) caused by hand-transmitted vibration (HTV). Little is known about the molecular mechanism of HAVS-induced vascular injuries. Herein, the iTRAQ (isobaric tags for relative and absolute quantitation) followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) proteomics approach was applied to conduct the quantitative proteomic analysis of plasma from specimens with HTV exposure or HAVS diagnosis. Overall, 726 proteins were identified in iTRAQ. 37 proteins upregulated and 43 downregulated in HAVS. Moreover, 37 upregulated and 40 downregulated when comparing severe HAVS and mild HAVS. Among them, Vinculin (VCL) was found to be downregulated in the whole process of HAVS. The concentration of vinculin was further verified by ELISA, and the results suggested that the proteomics data was reliable. Bioinformative analyses were used, and those proteins mainly engaged in specific biological processes like binding, focal adhesion, and integrins. The potential of vinculin application in HAVS diagnosis was validated by the receiver operating characteristic curve.
Topics: Humans; Hand-Arm Vibration Syndrome; Occupational Diseases; Vascular System Injuries; Vinculin; Chromatography, Liquid; Proteomics; Tandem Mass Spectrometry
PubMed: 37437295
DOI: 10.1021/acs.jproteome.3c00277 -
International Journal of Molecular... Jun 2023Glioblastoma multiforme (GBM) is one of the most aggressive types of cancer characterized by poor patient outcomes. To date, it is believed that the major cause of its...
Glioblastoma multiforme (GBM) is one of the most aggressive types of cancer characterized by poor patient outcomes. To date, it is believed that the major cause of its recurrence and chemoresistance is represented by the enrichment of GBM stem cells (GSCs) sustained by the abnormal activation of a number of signaling pathways. In this study, we found that in GBM cells, treatment with low toxicity doses of the γ-secretase inhibitor RO4929097 (GSI), blocking the Notch pathway activity, in combination with resveratrol (RSV) was able to reverse the basal mesenchymal phenotype to an epithelial-like phenotype, affecting invasion and stemness interplay. The mechanism was dependent on cyclin D1 and cyclin-dependent kinase (CDK4), leading to a reduction of paxillin (Pxn) phosphorylation. Consequently, we discovered the reduced interaction of Pxn with vinculin (Vcl), which, during cell migration, transmits the intracellular forces to the extracellular matrix. The exogenous expression of a constitutively active Cdk4 mutant prevented the RSV + GSI inhibitory effects in GBM cell motility/invasion and augmented the expression of stemness-specific markers, as well as the neurosphere sizes/forming abilities in untreated cells. In conclusion, we propose that Cdk4 is an important regulator of GBM stem-like phenotypes and invasive capacity, highlighting how the combined treatment of Notch inhibitors and RSV could be prospectively implemented in the novel therapeutic strategies to target Cdk4 for these aggressive brain tumors.
Topics: Humans; Glioblastoma; Resveratrol; Cell Line, Tumor; Brain Neoplasms; Signal Transduction; Neoplastic Stem Cells; Cell Proliferation
PubMed: 37373242
DOI: 10.3390/ijms241210094 -
Journal of Gastrointestinal and Liver... Jun 2023The aim of this study is to determine whether activated hepatic stellate cells (HSCs) may represent a prognostic marker of progressive liver fibrosis in chronic viral...
BACKGROUND AND AIMS
The aim of this study is to determine whether activated hepatic stellate cells (HSCs) may represent a prognostic marker of progressive liver fibrosis in chronic viral hepatitis C (VHC) before antiviral therapy. The possible correlation between HSCs immunohistochemical features, histopathological aspects and clinical data before therapy were also studied.
METHODS
This retrospective pilot study was conducted on 27 liver biopsies from VHC patients before antiviral therapy. HSCs's immunohistochemical analysis used the antibodies alpha-smooth muscle actin (α-SMA), glial fibrillary acidic protein (GFAP) and vinculin. We correlated immunopositive HSCs with HCV load, liver stiffness (LS), fibrosis stage and necro-inflammatory degree before treatment. Also, we assessed the association between liver fibrosis after therapy, the sustained virological response at 12 weeks after therapy (SVR 12) and the type of therapy.
RESULTS
HSCs were increased in VHC patients compared to controls, mainly in the intermediate and periportal lobular regions. α-SMA and vinculin HSCs correlated positively with fibrosis stage (p=0.044), (p=0.028). Furthermore, α-SMA and vinculin HSCs were associated with LS (p=0.027), (p=0.002) and viral load (p=0.021), (p=0.006), but not with necro-inflammation degree. GFAP HSCs inversely correlated with fibrosis stage (r= -0.475), LS (r= -0.422) and HCV load (r= -0.517), but positively with necro-inflammation degree (p=0.038). Liver fibrosis post therapy correlated positively with SVR12 (p<0.001) and the type of therapy (p=0.006) and SVR12 correlated positively with treatment's type (p=0.002).
CONCLUSIONS
Activated HSCs may represent a marker of increased liver fibrosis in VHC. Different immunohistochemical markers can detect various HSCs subpopulations involved in the evolution of VHC and liver fibrosis.
Topics: Humans; Hepatic Stellate Cells; Vinculin; Pilot Projects; Retrospective Studies; Liver; Hepatitis C, Chronic; Liver Cirrhosis; Fibrosis; Inflammation; Antiviral Agents
PubMed: 37345607
DOI: 10.15403/jgld-4726 -
Open Biology Jun 2023Adhesion between cells and the extracellular matrix is mediated by heterodimeric () integrin receptors that are intracellularly linked to the contractile actomyosin...
Adhesion between cells and the extracellular matrix is mediated by heterodimeric () integrin receptors that are intracellularly linked to the contractile actomyosin machinery. One of the proteins that control this link is talin, which organizes cytosolic signalling proteins into discrete complexes on β-integrin tails referred to as focal adhesions (FAs). The adapter protein KANK1 binds to talin in the region of FAs known as the adhesion belt. Here, we adapted a non-covalent crystallographic chaperone to resolve the talin-KANK1 complex. This structure revealed that the talin binding KN region of KANK1 contains a novel motif where a β-hairpin stabilizes the α-helical region, explaining both its specific interaction with talin R7 and high affinity. Single point mutants in KANK1 identified from the structure abolished the interaction and enabled us to examine KANK1 enrichment in the adhesion belt. Strikingly, in cells expressing a constitutively active form of vinculin that keeps the FA structure intact even in the presence of myosin inhibitors, KANK1 localizes throughout the entire FA structure even when actomyosin tension is released. We propose a model whereby actomyosin forces on talin eliminate KANK1 from talin binding in the centre of FAs while retaining it at the adhesion periphery.
Topics: Actins; Focal Adhesions; Talin; Actomyosin; Cell Adhesion; Cytoskeleton; Vinculin; Integrins; Microtubules
PubMed: 37339751
DOI: 10.1098/rsob.230058 -
Molecular Vision 2023To understand which cell types, either alone or in combination, contribute to the assembly of the epithelial basement membrane (BM) during corneal wound healing.
PURPOSE
To understand which cell types, either alone or in combination, contribute to the assembly of the epithelial basement membrane (BM) during corneal wound healing.
METHODS
A 3D corneal organotypic model and an in situ rabbit photorefractive keratectomy (PRK) model were used in this study. The 3D corneal organotypic model was established by culturing the rabbit corneal epithelial cells with either corneal fibroblasts or myofibroblasts embedded in collagen type I for 18 days. Corneal fibroblasts were isolated from fresh rabbit corneas, and the myofibroblasts were derived either directly from bone marrow or differentiated from corneal fibroblasts. Immunocytochemistry for alpha-smooth muscle actin (SMA), vimentin, desmin, and vinculin markers confirmed well-differentiated myofibroblasts. Immunohistochemistry was performed in cryofixed sections for BM markers, including laminin alpha-5, laminin beta-3, perlecan, nidogen-1, and collagen type IV. Specimens were also examined with transmission electron microscopy (TEM). Corneas were collected from rabbits after -3 diopter (D) PRK at different time points after surgery, with four corneas at each time point in each group. Cryofixed corneal sections were stained for vimentin, alpha-SMA, and nidogen-1.
RESULTS
The formation of an epithelial BM with expression of laminin alpha-5, laminin beta-3, perlecan, nidogen-1, and collagen IV was observed at the interface between the corneal epithelial cells and corneal fibroblasts. TEM images further confirmed the presence of epithelial BM in organotypic cultures of epithelial cells and corneal fibroblasts. No epithelial BM was observed in cultures of corneal epithelial cells and myofibroblasts (cornea or bone marrow derived), corneal epithelial cells alone, or corneal fibroblasts alone. In rabbit corneas after -3D PRK, a strong association was observed between the regenerating epithelial BM and the presence of corneal fibroblasts at the site of epithelial BM generation.
CONCLUSIONS
The corneal epithelial BM assembly is mediated by epithelial cells in coordination with corneal fibroblasts during wound healing.
Topics: Animals; Rabbits; Laminin; Vimentin; Cornea; Fibroblasts; Wound Healing; Photorefractive Keratectomy; Extracellular Matrix Proteins; Epithelial Cells; Basement Membrane; Corneal Stroma
PubMed: 37287640
DOI: No ID Found -
Journal of Cell Science Jun 2023Vinculin is an actin-binding protein present at cell-matrix and cell-cell adhesions, which plays a critical role in bearing force experienced by cells and dissipating it...
Vinculin is an actin-binding protein present at cell-matrix and cell-cell adhesions, which plays a critical role in bearing force experienced by cells and dissipating it onto the cytoskeleton. Recently, we identified a key tyrosine residue, Y822, whose phosphorylation plays a critical role in force transmission at cell-cell adhesions. The role of Y822 in human cancer remains unknown, even though Y822 is mutated to Y822C in uterine cancers. Here, we investigated the effect of this amino acid substitution and that of a phosphodeficient Y822F vinculin in cancer cells. We observed that the presence of the Y822C mutation led to cells that proliferate and migrate more rapidly and contained smaller focal adhesions when compared to cells with wild-type vinculin. In contrast, the presence of the Y822F mutation led to highly spread cells with larger focal adhesions and increased contractility. Furthermore, we provide evidence that Y822C vinculin forms a disulfide bond with paxillin, accounting for some of the elevated phosphorylated paxillin recruitment. Taken together, these data suggest that vinculin Y822 modulates the recruitment of ligands.
Topics: Humans; Vinculin; Paxillin; Ligands; Cell Adhesion; Cell Communication; Focal Adhesions
PubMed: 37248996
DOI: 10.1242/jcs.260104 -
International Journal of Molecular... May 2023Therapy with anti-tumor necrosis factor (TNF) has dramatically changed the natural history of Crohn's disease (CD). However, these drugs are not without adverse events,...
Therapy with anti-tumor necrosis factor (TNF) has dramatically changed the natural history of Crohn's disease (CD). However, these drugs are not without adverse events, and up to 40% of patients could lose efficacy in the long term. We aimed to identify reliable markers of response to anti-TNF drugs in patients with CD. A consecutive cohort of 113 anti-TNF naive patients with CD was stratified according to clinical response as short-term remission (STR) or non-STR (NSTR) at 12 weeks of treatment. We compared the protein expression profiles of plasma samples in a subset of patients from both groups prior to anti-TNF therapy by SWATH proteomics. We identified 18 differentially expressed proteins ( ≤ 0.01, fold change ≥ 2.4) involved in the organization of the cytoskeleton and cell junction, hemostasis/platelet function, carbohydrate metabolism, and immune response as candidate biomarkers of STR. Among them, vinculin was one of the most deregulated proteins ( < 0.001), whose differential expression was confirmed by ELISA ( = 0.054). In the multivariate analysis, plasma vinculin levels along with basal CD Activity Index, corticosteroids induction, and bowel resection were factors predicting NSTR.
Topics: Humans; Crohn Disease; Tumor Necrosis Factor Inhibitors; Vinculin; Tumor Necrosis Factor-alpha; Antineoplastic Agents; Remission Induction; Infliximab
PubMed: 37240037
DOI: 10.3390/ijms24108695 -
Biomedicines May 2023A chronic subdural hematoma (CSDH) is considered to be an inflammatory and angiogenic disease. The CSDH outer membrane, which contains inflammatory cells, plays an...
BACKGROUND
A chronic subdural hematoma (CSDH) is considered to be an inflammatory and angiogenic disease. The CSDH outer membrane, which contains inflammatory cells, plays an important role in CSDH development. Osteopontin (OPN) is an extracellular matrix protein that is cleaved by thrombin, generating the N-terminal half of OPN, which is prominently involved in integrin signal transduction. We explored the expression of the N-terminal half of OPN in CSDH fluid and the expression of integrins α9 and β1 and the downstream components of the angiogenic signaling pathways in the outer membrane of CSDHs.
METHODS
Twenty samples of CSDH fluid and eight samples of CSDH outer membrane were collected from patients suffering from CSDHs. The concentrations of the N-terminal half of OPN in CSDH fluid samples were measured using ELISA kits. The expression levels of integrins α9 and β1, vinculin, talin-1, focal adhesion kinase (FAK), paxillin, α-actin, Src and β-actin were examined by Western blot analysis. The expression levels of integrins α9 and β1, FAK and paxillin were also examined by immunohistochemistry. We investigated whether CSDH fluid could activate FAK in cultured endothelial cells in vitro.
RESULTS
The concentration of the N-terminal half of OPN in CSDH fluid was significantly higher than that in the serum. Western blot analysis confirmed the presence of these molecules. In addition, integrins α9 and β1, FAK and paxillin were localized in the endothelial cells of vessels within the CSDH outer membrane. FAK was significantly phosphorylated immediately after treatment with CSDH fluid.
CONCLUSION
Our data suggest that the N-terminal half of OPN in CSDH fluid promotes neovascularization in endothelial cells through integrins α9 and β1. The N-terminal half of OPN, which is part of the extracellular matrix, plays a critical role in the promotion of CSDHs.
PubMed: 37239111
DOI: 10.3390/biomedicines11051440