The Experts below are selected from a list of 69186 Experts worldwide ranked by ideXlab platform
Martin A Schwartz - One of the best experts on this subject based on the ideXlab platform.
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fluid shear stress on endothelial cells modulates Mechanical Tension across ve cadherin and pecam 1
2013Co-Authors: Daniel E. Conway, Martin A Schwartz, Christopher S Chen, Mark T Breckenridge, Elizabeth Hinde, Enrico GrattonAbstract:Summary Fluid shear stress (FSS) from blood flow acting on the endothelium critically regulates vascular morphogenesis, blood pressure, and atherosclerosis [1]. FSS applied to endothelial cells (ECs) triggers signaling events including opening of ion channels, activation of signaling pathways, and changes in gene expression. Elucidating how ECs sense flow is important for understanding both normal vascular function and disease. EC responses to FSS are mediated in part by a junctional mechanosensory complex consisting of VE-cadherin, PECAM-1, and VEGFR2 [2]. Previous work suggested that flow increases force on PECAM-1, which initiates signaling [2–4]. Deletion of PECAM-1 blocks responses to flow in vitro and flow-dependent vascular remodeling in vivo [2, 5]. To understand this process, we developed and validated FRET-based Tension sensors for VE-cadherin and PECAM-1 using our previously developed FRET Tension biosensor [6]. FRET measurements showed that in static culture, VE-cadherin in cell-cell junctions bears significant myosin-dependent Tension, whereas there was no detectable Tension on VE-cadherin outside of junctions. Onset of shear stress triggered a rapid (
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fluid shear stress on endothelial cells modulates Mechanical Tension across ve cadherin and pecam 1
2013Co-Authors: Daniel E. Conway, Martin A Schwartz, Christopher S Chen, Mark T Breckenridge, Elizabeth Hinde, Enrico GrattonAbstract:Fluid shear stress (FSS) from blood flow acting on the endothelium critically regulates vascular morphogenesis, blood pressure, and atherosclerosis. FSS applied to endothelial cells (ECs) triggers signaling events including opening of ion channels, activation of signaling pathways, and changes in gene expression. Elucidating how ECs sense flow is important for understanding both normal vascular function and disease. EC responses to FSS are mediated in part by a junctional mechanosensory complex consisting of VE-cadherin, PECAM-1, and VEGFR2. Previous work suggested that flow increases force on PECAM-1, which initiates signaling. Deletion of PECAM-1 blocks responses to flow in vitro and flow-dependent vascular remodeling in vivo. To understand this process, we developed and validated FRET-based Tension sensors for VE-cadherin and PECAM-1 using our previously developed FRET Tension biosensor. FRET measurements showed that in static culture, VE-cadherin in cell-cell junctions bears significant myosin-dependent Tension, whereas there was no detectable Tension on VE-cadherin outside of junctions. Onset of shear stress triggered a rapid (<30 s) decrease in Tension across VE-cadherin, which paralleled a decrease in total cell-cell junctional Tension. Flow triggered a simultaneous increase in Tension across junctional PECAM-1, while nonjunctional PECAM-1 was unaffected. Tension on PECAM-1 was mediated by flow-stimulated association with vimentin. These data confirm the prediction that shear increases force on PECAM-1. However, they also argue against the current model of passive transfer of force through the cytoskeleton to the junctions, showing instead that flow triggers cytoskeletal remodeling, which alters forces across the junctional receptors.
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measuring Mechanical Tension across vinculin reveals regulation of focal adhesion dynamics
2010Co-Authors: Carsten Grashoff, Christopher S Chen, Brenton D Hoffman, Michael D Brenner, Ruobo Zhou, Madeline Parsons, Michael T Yang, Mark A Mclean, Stephen G Sligar, Martin A SchwartzAbstract:Mechanical forces are central to developmental, physiological and pathological processes. However, limited understanding of force transmission within sub-cellular structures is a major obstacle to unravelling molecular mechanisms. Here we describe the development of a calibrated biosensor that measures forces across specific proteins in cells with piconewton (pN) sensitivity, as demonstrated by single molecule fluorescence force spectroscopy. The method is applied to vinculin, a protein that connects integrins to actin filaments and whose recruitment to focal adhesions (FAs) is force-dependent. We show that Tension across vinculin in stable FAs is approximately 2.5 pN and that vinculin recruitment to FAs and force transmission across vinculin are regulated separately. Highest Tension across vinculin is associated with adhesion assembly and enlargement. Conversely, vinculin is under low force in disassembling or sliding FAs at the trailing edge of migrating cells. Furthermore, vinculin is required for stabilizing adhesions under force. Together, these data reveal that FA stabilization under force requires both vinculin recruitment and force transmission, and that, surprisingly, these processes can be controlled independently.
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cadherin adhesion tissue Tension and noncanonical wnt signaling regulate fibronectin matrix organization
2009Co-Authors: Bette J Dzamba, Martin A Schwartz, Karoly Jakab, Mungo Marsden, Douglas W DesimoneAbstract:In this study we demonstrate that planar cell polarity signaling regulates morphogenesis in Xenopus embryos in part through the assembly of the fibronectin (FN) matrix. We outline a regulatory pathway that includes cadherin adhesion and signaling through Rac and Pak, culminating in actin reorganization, myosin contractility, and tissue Tension, which, in turn, directs the correct spatiotemporal localization of FN into a fibrillar matrix. Increased Mechanical Tension promotes FN fibril assembly in the blastocoel roof (BCR), while reduced BCR Tension inhibits matrix assembly. These data support a model for matrix assembly in tissues where cell-cell adhesions play an analogous role to the focal adhesions of cultured cells by transferring to integrins the Tension required to direct FN fibril formation at cell surfaces.
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integrin activation and matrix binding mediate cellular responses to Mechanical stretch
2005Co-Authors: Akira Katsumi, Tomoki Naoe, Tadashi Matsushita, Kozo Kaibuchi, Martin A SchwartzAbstract:Abstract Mechanical Tension is a critical determinant of cell growth, differentiation, apoptosis, migration, and development. Integrins have been implicated in sensing force but little is known about how forces are transduced to biochemical signals. We now show that Mechanical strain stimulates conformational activation of integrin αvβ3 in NIH3T3 cells. Integrin activation is mediated by phosphoinositol 3-kinase and is followed by an increase in integrin binding to extracellular matrix proteins. Mechanical stretch stimulation of JNK was dependent on new integrin binding to extracellular matrix. These data define a molecular mechanism for the role of integrins in mechanotransduction.
Axel Behrens - One of the best experts on this subject based on the ideXlab platform.
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tissue curvature and apicobasal Mechanical Tension imbalance instruct cancer morphogenesis
2019Co-Authors: Hendrik A Messal, Rute M M Ferreira, Christopher Gribben, Victoria Wang, Corina Cotoi, Guillaume Salbreux, Axel BehrensAbstract:Tubular epithelia are a basic building block of organs and a common site of cancer occurrence1–4. During tumorigenesis, transformed cells overproliferate and epithelial architecture is disrupted. However, the biophysical parameters that underlie the adoption of abnormal tumour tissue shapes are unknown. Here we show in the pancreas of mice that the morphology of epithelial tumours is determined by the interplay of cytoskeletal changes in transformed cells and the existing tubular geometry. To analyse the morphological changes in tissue architecture during the initiation of cancer, we developed a three-dimensional whole-organ imaging technique that enables tissue analysis at single-cell resolution. Oncogenic transformation of pancreatic ducts led to two types of neoplastic growth: exophytic lesions that expanded outwards from the duct and endophytic lesions that grew inwards to the ductal lumen. Myosin activity was higher apically than basally in wild-type cells, but upon transformation this gradient was lost in both lesion types. Three-dimensional vertex model simulations and a continuum theory of epithelial mechanics, which incorporate the cytoskeletal changes observed in transformed cells, indicated that the diameter of the source epithelium instructs the morphology of growing tumours. Three-dimensional imaging revealed that—consistent with theory predictions—small pancreatic ducts produced exophytic growth, whereas large ducts deformed endophytically. Similar patterns of lesion growth were observed in tubular epithelia of the liver and lung; this finding identifies Tension imbalance and tissue curvature as fundamental determinants of epithelial tumorigenesis. Three-dimensional imaging of mouse pancreatic ducts before and after oncogenic transformation reveals that epithelial tumorigenesis is determined by the relationship between tissue curvature and apical–basal Mechanical Tension.
Christopher S Chen - One of the best experts on this subject based on the ideXlab platform.
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fluid shear stress on endothelial cells modulates Mechanical Tension across ve cadherin and pecam 1
2013Co-Authors: Daniel E. Conway, Martin A Schwartz, Christopher S Chen, Mark T Breckenridge, Elizabeth Hinde, Enrico GrattonAbstract:Summary Fluid shear stress (FSS) from blood flow acting on the endothelium critically regulates vascular morphogenesis, blood pressure, and atherosclerosis [1]. FSS applied to endothelial cells (ECs) triggers signaling events including opening of ion channels, activation of signaling pathways, and changes in gene expression. Elucidating how ECs sense flow is important for understanding both normal vascular function and disease. EC responses to FSS are mediated in part by a junctional mechanosensory complex consisting of VE-cadherin, PECAM-1, and VEGFR2 [2]. Previous work suggested that flow increases force on PECAM-1, which initiates signaling [2–4]. Deletion of PECAM-1 blocks responses to flow in vitro and flow-dependent vascular remodeling in vivo [2, 5]. To understand this process, we developed and validated FRET-based Tension sensors for VE-cadherin and PECAM-1 using our previously developed FRET Tension biosensor [6]. FRET measurements showed that in static culture, VE-cadherin in cell-cell junctions bears significant myosin-dependent Tension, whereas there was no detectable Tension on VE-cadherin outside of junctions. Onset of shear stress triggered a rapid (
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fluid shear stress on endothelial cells modulates Mechanical Tension across ve cadherin and pecam 1
2013Co-Authors: Daniel E. Conway, Martin A Schwartz, Christopher S Chen, Mark T Breckenridge, Elizabeth Hinde, Enrico GrattonAbstract:Fluid shear stress (FSS) from blood flow acting on the endothelium critically regulates vascular morphogenesis, blood pressure, and atherosclerosis. FSS applied to endothelial cells (ECs) triggers signaling events including opening of ion channels, activation of signaling pathways, and changes in gene expression. Elucidating how ECs sense flow is important for understanding both normal vascular function and disease. EC responses to FSS are mediated in part by a junctional mechanosensory complex consisting of VE-cadherin, PECAM-1, and VEGFR2. Previous work suggested that flow increases force on PECAM-1, which initiates signaling. Deletion of PECAM-1 blocks responses to flow in vitro and flow-dependent vascular remodeling in vivo. To understand this process, we developed and validated FRET-based Tension sensors for VE-cadherin and PECAM-1 using our previously developed FRET Tension biosensor. FRET measurements showed that in static culture, VE-cadherin in cell-cell junctions bears significant myosin-dependent Tension, whereas there was no detectable Tension on VE-cadherin outside of junctions. Onset of shear stress triggered a rapid (<30 s) decrease in Tension across VE-cadherin, which paralleled a decrease in total cell-cell junctional Tension. Flow triggered a simultaneous increase in Tension across junctional PECAM-1, while nonjunctional PECAM-1 was unaffected. Tension on PECAM-1 was mediated by flow-stimulated association with vimentin. These data confirm the prediction that shear increases force on PECAM-1. However, they also argue against the current model of passive transfer of force through the cytoskeleton to the junctions, showing instead that flow triggers cytoskeletal remodeling, which alters forces across the junctional receptors.
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measuring Mechanical Tension across vinculin reveals regulation of focal adhesion dynamics
2010Co-Authors: Carsten Grashoff, Christopher S Chen, Brenton D Hoffman, Michael D Brenner, Ruobo Zhou, Madeline Parsons, Michael T Yang, Mark A Mclean, Stephen G Sligar, Martin A SchwartzAbstract:Mechanical forces are central to developmental, physiological and pathological processes. However, limited understanding of force transmission within sub-cellular structures is a major obstacle to unravelling molecular mechanisms. Here we describe the development of a calibrated biosensor that measures forces across specific proteins in cells with piconewton (pN) sensitivity, as demonstrated by single molecule fluorescence force spectroscopy. The method is applied to vinculin, a protein that connects integrins to actin filaments and whose recruitment to focal adhesions (FAs) is force-dependent. We show that Tension across vinculin in stable FAs is approximately 2.5 pN and that vinculin recruitment to FAs and force transmission across vinculin are regulated separately. Highest Tension across vinculin is associated with adhesion assembly and enlargement. Conversely, vinculin is under low force in disassembling or sliding FAs at the trailing edge of migrating cells. Furthermore, vinculin is required for stabilizing adhesions under force. Together, these data reveal that FA stabilization under force requires both vinculin recruitment and force transmission, and that, surprisingly, these processes can be controlled independently.
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measuring Mechanical Tension across vinculin reveals regulation of focal adhesion dynamics
2010Co-Authors: Carsten Grashoff, Christopher S Chen, Brenton D Hoffman, Michael D Brenner, Ruobo Zhou, Madeline Parsons, Michael T Yang, Mark A Mclean, Stephen G Sligar, Taekjip HaAbstract:The ability of cells to respond to physical forces is fundamental to development and physiology, including regulation of blood pressure, cell adhesion and migration. A major limitation to the study of these phenomena has been the difficulty of measuring molecular forces in cells in vivo. Grashoff et al. now report the development of a genetically encoded, fluorescent Tension-sensing module capable of measuring Mechanical forces across specific proteins in vivo. The sensor was tested on vinculin, a membrane-cytoskeletal protein that is recruited to focal adhesions and connects cell-adhesion molecules (integrins) to actin filaments. The data reveal a regulatory mechanism in which the ability of vinculin to bear force determines whether focal adhesions assemble or disassemble under force. This new biosensor should be applicable to other proteins involved in mechanotransduction. The ability of cells to respond to physical forces is central to development and physiology, but until now it has been difficult to directly measure forces across proteins in vivo. Here, however, a calibrated biosensor is described that can measure forces with high sensitivity across specific proteins in cells. This is applied to the vinculin protein, and a regulatory mechanism is revealed in which the force applied to vinculin determines whether focal adhesions assemble or disassemble. Mechanical forces are central to developmental, physiological and pathological processes1. However, limited understanding of force transmission within sub-cellular structures is a major obstacle to unravelling molecular mechanisms. Here we describe the development of a calibrated biosensor that measures forces across specific proteins in cells with piconewton (pN) sensitivity, as demonstrated by single molecule fluorescence force spectroscopy2. The method is applied to vinculin, a protein that connects integrins to actin filaments and whose recruitment to focal adhesions (FAs) is force-dependent3. We show that Tension across vinculin in stable FAs is ∼2.5 pN and that vinculin recruitment to FAs and force transmission across vinculin are regulated separately. Highest Tension across vinculin is associated with adhesion assembly and enlargement. Conversely, vinculin is under low force in disassembling or sliding FAs at the trailing edge of migrating cells. Furthermore, vinculin is required for stabilizing adhesions under force. Together, these data reveal that FA stabilization under force requires both vinculin recruitment and force transmission, and that, surprisingly, these processes can be controlled independently.
Andrew Leask - One of the best experts on this subject based on the ideXlab platform.
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A (2011) Mechanical Tension increases CCN2/CTGF expression and proliferation in gingival fibroblasts via a TGFb-dependent mechanism. PLoS One2011; 6(5): e19756
2013Co-Authors: Fen Guo, David E Carter, Andrew LeaskAbstract:Unlike skin, oral gingival do not scar in response to tissue injury. Fibroblasts, the cell type responsible for connective tissue repair and scarring, are exposed to Mechanical Tension during normal and pathological conditions including wound healing and fibrogenesis. Understanding how human gingival fibroblasts respond to Mechanical Tension is likely to yield valuable insights not only into gingival function but also into the molecular basis of scarless repair. CCN2/connective tissue growth factor is potently induced in fibroblasts during tissue repair and fibrogenesis. We subjected gingival fibroblasts to cyclical strain (up to 72 hours) using the Flexercell system and showed that CCN2 mRNA and protein was induced by strain. Strain caused the rapid activation of latent TGFb, in a fashion that was reduced by blebbistatin and FAK/src inhibition, and the induction of endothelin (ET-1) mRNA and protein expression. Strain did not cause induction of a-smooth muscle actin or collagen type I mRNAs (proteins promoting scarring); but induced a cohort of pro-proliferative mRNAs and cell proliferation. Compared to dermal fibroblasts, gingival fibroblasts showed reduced ability to respond to TGFb by inducing fibrogenic mRNAs; addition of ET-1 rescued this phenotype. Pharmacological inhibition of the TGFb type I (ALK5) receptor, the endothelin A/B receptors and FAK/src significantly reduced the induction of CCN2 and pro-proliferative mRNAs and cell proliferation. Controlling TGFb, ET-1 and FAK/src activity may be useful in controlling responses to Mechanical strain in the gingiva and may be of value in controlling fibroproliferative conditions such as gingival hyperplasia; controlling ET-1 may b
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Mechanical Tension increases ccn2 ctgf expression and proliferation in gingival fibroblasts via a tgfβ dependent mechanism
2011Co-Authors: David E Carter, Andrew LeaskAbstract:Unlike skin, oral gingival do not scar in response to tissue injury. Fibroblasts, the cell type responsible for connective tissue repair and scarring, are exposed to Mechanical Tension during normal and pathological conditions including wound healing and fibrogenesis. Understanding how human gingival fibroblasts respond to Mechanical Tension is likely to yield valuable insights not only into gingival function but also into the molecular basis of scarless repair. CCN2/connective tissue growth factor is potently induced in fibroblasts during tissue repair and fibrogenesis. We subjected gingival fibroblasts to cyclical strain (up to 72 hours) using the Flexercell system and showed that CCN2 mRNA and protein was induced by strain. Strain caused the rapid activation of latent TGFβ, in a fashion that was reduced by blebbistatin and FAK/src inhibition, and the induction of endothelin (ET-1) mRNA and protein expression. Strain did not cause induction of α-smooth muscle actin or collagen type I mRNAs (proteins promoting scarring); but induced a cohort of pro-proliferative mRNAs and cell proliferation. Compared to dermal fibroblasts, gingival fibroblasts showed reduced ability to respond to TGFβ by inducing fibrogenic mRNAs; addition of ET-1 rescued this phenotype. Pharmacological inhibition of the TGFβ type I (ALK5) receptor, the endothelin A/B receptors and FAK/src significantly reduced the induction of CCN2 and pro-proliferative mRNAs and cell proliferation. Controlling TGFβ, ET-1 and FAK/src activity may be useful in controlling responses to Mechanical strain in the gingiva and may be of value in controlling fibroproliferative conditions such as gingival hyperplasia; controlling ET-1 may be of benefit in controlling scarring in response to injury in the skin.
Keith Burridge - One of the best experts on this subject based on the ideXlab platform.
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focal adhesions stress fibers and Mechanical Tension
2016Co-Authors: Keith Burridge, Christophe GuilluyAbstract:Stress fibers and focal adhesions are complex protein arrays that produce, transmit and sense Mechanical Tension. Evidence accumulated over many years led to the conclusion that Mechanical Tension generated within stress fibers contributes to the assembly of both stress fibers themselves and their associated focal adhesions. However, several lines of evidence have recently been presented against this model. Here we discuss the evidence for and against the role of Mechanical Tension in driving the assembly of these structures. We also consider how their assembly is influenced by the rigidity of the substratum to which cells are adhering. Finally, we discuss the recently identified connections between stress fibers and the nucleus, and the roles that these may play, both in cell migration and regulating nuclear function.
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the Tension mounts stress fibers as force generating mechanotransducers
2013Co-Authors: Keith Burridge, Erika S WittchenAbstract:Stress fibers (SFs) are often the most prominent cytoskeletal structures in cells growing in tissue culture. Composed of actin filaments, myosin II, and many other proteins, SFs are force-generating and Tension-bearing structures that respond to the surrounding physical environment. New work is shedding light on the mechanosensitive properties of SFs, including that these structures can respond to Mechanical Tension by rapid reinforcement and that there are mechanisms to repair strain-induced damage. Although SFs are superficially similar in organization to the sarcomeres of striated muscle, there are intriguing differences in their organization and behavior, indicating that much still needs to be learned about these structures.