The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Christopher S Chen - One of the best experts on this subject based on the ideXlab platform.
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Cell Shape and substrate rigidity both regulate Cell stiffness
Biophysical Journal, 2011Co-Authors: Shang You Tee, Christopher S Chen, Paul A JanmeyAbstract:Cells from many different tissues sense the stiffness and spatial patterning of their microenvironment to modulate their Shape and cortical stiffness. It is currently unknown how substrate stiffness, Cell Shape, and Cell stiffness modulate or interact with one another. Here, we use microcontact printing and microfabricated arrays of elastomeric posts to independently and simultaneously control Cell Shape and substrate stiffness. Our experiments show that Cell cortical stiffness increases as a function of both substrate stiffness and spread area. For soft substrates, the influence of substrate stiffness on Cell cortical stiffness is more prominent than that of Cell Shape, since increasing adherent area does not lead to Cell stiffening. On the other hand, for Cells constrained to a small area, Cell Shape effects are more dominant than substrate stiffness, since increasing substrate stiffness no longer affects Cell stiffness. These results suggest that Cell size and substrate stiffness can interact in a complex fashion to either enhance or antagonize each other's effect on Cell morphology and mechanics.
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stem Cell Shape regulates a chondrogenic versus myogenic fate through rac1 and n cadherin
Stem Cells, 2010Co-Authors: Lin Gao, Rowena Mcbeath, Christopher S ChenAbstract:Human mesenchymal stem Cells (hMSCs) are multipotent Cells that can differentiate into many Cell types. Chondrogenesis is induced in hMSCs cultured as a micromass pellet to mimic Cellular condensation during cartilage development, and exposed to transforming growth factor beta (TGFbeta). Interestingly, TGFbeta can also induce hMSC differentiation to smooth-muscle-like Cell types, but it remains unclear what directs commitment between these two lineages. Our previous work revealed that Cell Shape regulates hMSC commitment between osteoblasts and adipocytes through RhoA signaling. Here we show that Cell Shape also confers a switch between chondrogenic and smooth muscle Cell (SMC) fates. Adherent and well-spread hMSCs stimulated with TGF beta 3 upregulated SMC genes, whereas Cells allowed to attach onto micropatterned substrates, but prevented from spreading and flattening, upregulated chondrogenic genes. Interestingly, Cells undergoing SMC differentiation exhibited little change in RhoA, but significantly higher Rac1 activity than chondrogenic Cells. Rac1 activation inhibited chondrogenesis and was necessary and sufficient for inducing SMC differentiation. Furthermore, TGF beta 3 and Rac1 signaling upregulated N-cadherin, which was required for SMC differentiation. These results demonstrate a chondrogenic-SMC fate decision mediated by Cell Shape, Rac1, and N-cadherin, and highlight the tight coupling between lineage commitment and the many changes in Cell Shape, Cell-matrix adhesion, and Cell-Cell adhesion that occur during morphogenesis.
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Cell Shape cytoskeletal tension and rhoa regulate stem Cell lineage commitment
Developmental Cell, 2004Co-Authors: Rowena Mcbeath, Dana M Pirone, Celeste M Nelson, Kiran Bhadriraju, Christopher S ChenAbstract:Commitment of stem Cells to different lineages is regulated by many cues in the local tissue microenvironment. Here we demonstrate that Cell Shape regulates commitment of human mesenchymal stem Cells (hMSCs) to adipocyte or osteoblast fate. hMSCs allowed to adhere, flatten, and spread underwent osteogenesis, while unspread, round Cells became adipocytes. Cell Shape regulated the switch in lineage commitment by modulating endogenous RhoA activity. Expressing dominant-negative RhoA committed hMSCs to become adipocytes, while constitutively active RhoA caused osteogenesis. However, the RhoA-mediated adipogenesis or osteogenesis was conditional on a round or spread Shape, respectively, while constitutive activation of the RhoA effector, ROCK, induced osteogenesis independent of Cell Shape. This RhoA-ROCK commitment signal required actin-myosin-generated tension. These studies demonstrate that mechanical cues experienced in developmental and adult contexts, embodied by Cell Shape, cytoskeletal tension, and RhoA signaling, are integral to the commitment of stem Cell fate.
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micropatterned surfaces for control of Cell Shape position and function
Biotechnology Progress, 1998Co-Authors: Christopher S Chen, Milan Mrksich, Sui Huang, George M Whitesides, Donald E IngberAbstract:The control of Cell position and function is a fundamental focus in the development of applications ranging from Cellular biosensors to tissue engineering. Using microcontact printing of self-assembled monolayers (SAMs) of alkanethiolates on gold, we manufactured substrates that contained micrometer-scale islands of extraCellular matrix (ECM) separated by nonadhesive regions such that the pattern of islands determined the distribution and position of bovine and human endothelial Cells. In addition, the size and geometry of the islands were shown to control Cell Shape. Traditional approaches to modulate Cell Shape, either by attaching suspended Cells to microbeads of different sizes or by plating Cells on substrates coated with different densities of ECM, suggested that Cell Shape may play an important role in control of apoptosis as well as growth. Data are presented which show how micropatterned substrates were used to definitively test this hypothesis. Progressively restricting bovine and human endothelial Cell extension by culturing Cells on smaller and smaller micropatterned adhesive islands regulated a transition from growth to apoptosis on a single continuum of Cell spreading, thus confirming the central role of Cell Shape in Cell function. The micropatterning technology is therefore essential not only for construction of biosurface devices but also for the investigation of the fundamental biology of Cell-ECM interactions.
Donald E Ingber - One of the best experts on this subject based on the ideXlab platform.
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viscoelastic retraction of single living stress fibers and its impact on Cell Shape cytoskeletal organization and extraCellular matrix mechanics
Biophysical Journal, 2006Co-Authors: Sanjay Kumar, Thomas R Polte, Iva Z Maxwell, Alexander Heisterkamp, Tanmay P Lele, Matthew C Salanga, Eric Mazur, Donald E IngberAbstract:Cells change their form and function by assembling actin stress fibers at their base and exerting traction forces on their extraCellular matrix (ECM) adhesions. Individual stress fibers are thought to be actively tensed by the action of actomyosin motors and to function as elastic cables that structurally reinforce the basal portion of the cytoskeleton; however, these principles have not been directly tested in living Cells, and their significance for overall Cell Shape control is poorly understood. Here we combine a laser nanoscissor, traction force microscopy, and fluorescence photobleaching methods to confirm that stress fibers in living Cells behave as viscoelastic cables that are tensed through the action of actomyosin motors, to quantify their retraction kinetics in situ, and to explore their contribution to overall mechanical stability of the Cell and interconnected ECM. These studies reveal that viscoelastic recoil of individual stress fibers after laser severing is partially slowed by inhibition of Rho-associated kinase and virtually abolished by direct inhibition of myosin light chain kinase. Importantly, Cells cultured on stiff ECM substrates can tolerate disruption of multiple stress fibers with negligible overall change in Cell Shape, whereas disruption of a single stress fiber in Cells anchored to compliant ECM substrates compromises the entire Cellular force balance, induces cytoskeletal rearrangements, and produces ECM retraction many microns away from the site of incision; this results in large-scale changes of Cell Shape (> 5% elongation). In addition to revealing fundamental insight into the mechanical properties and Cell Shape contributions of individual stress fibers and confirming that the ECM is effectively a physical extension of the Cell and cytoskeleton, the technologies described here offer a novel approach to spatially map the cytoskeletal mechanics of living Cells on the nanoscale.
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caldesmon dependent switching between capillary endothelial Cell growth and apoptosis through modulation of Cell Shape and contractility
Angiogenesis, 2003Co-Authors: Yasushi Numaguchi, Sui Huang, Thomas R Polte, Gabriel S Eichler, Ning Wang, Donald E IngberAbstract:Caldesmon (CaD), a protein component of the actomyosin filament apparatus, modulates Cell Shape and cytoskeletal structure when overexpressed. When capillary endothelial Cells were infected with an adenoviral vector encoding GFP-CaD under Tet-Off control, progressive inhibition of contractility, loss of actin stress fibers, disassembly of focal adhesions, and Cell retraction resulted. This was accompanied by a Cell Shape (rounding)-dependent increase in apoptosis and concomitant inhibition of Cell cycle progression. Cell growth also was inhibited in low expressor Cells in which Cell tension was suppressed independently of significant changes in Cell Shape, cytoskeletal structure, or focal adhesions. Thus, changes in both cytoskeletal structure and contractility appear to be central to the mechanism by which extraCellular matrix-dependent changes in capillary Cell Shape influence growth and apoptosis during angiogenesis, and hence the cytoskeleton may represent a potential target for anti-angiogenesis therapy.
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intact vinculin protein is required for control of Cell Shape Cell mechanics and rac dependent lamellipodia formation
Biochemical and Biophysical Research Communications, 2002Co-Authors: Wolfgang H Goldmann, Donald E IngberAbstract:Studies were carried out using vinculin-deficient F9 embryonic carcinoma (gamma229) Cells to analyze the relationship between structure and function within the focal adhesion protein vinculin, in the context of control of Cell Shape, Cell mechanics, and movement. Atomic force microscopy studies revealed that transfection of the head (aa 1-821) or tail (aa 811-1066) domain of vinculin, alone or together, was unable to fully reverse the decrease in Cell stiffness, spreading, and lamellipodia formation caused by vinculin deficiency. In contrast, replacement with intact vinculin completely restored normal Cell mechanics and spreading regardless of whether its tyrosine phosphorylation site was deleted. Constitutively active rac also only induced extension of lamellipodia when microinjected into Cells that expressed intact vinculin protein. These data indicate that vinculin's ability to physically couple integrins to the cytoskeleton, to mechanically stabilize Cell Shape, and to support rac-dependent lamellipodia formation all appear to depend on its intact three-dimensional structure.
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micropatterned surfaces for control of Cell Shape position and function
Biotechnology Progress, 1998Co-Authors: Christopher S Chen, Milan Mrksich, Sui Huang, George M Whitesides, Donald E IngberAbstract:The control of Cell position and function is a fundamental focus in the development of applications ranging from Cellular biosensors to tissue engineering. Using microcontact printing of self-assembled monolayers (SAMs) of alkanethiolates on gold, we manufactured substrates that contained micrometer-scale islands of extraCellular matrix (ECM) separated by nonadhesive regions such that the pattern of islands determined the distribution and position of bovine and human endothelial Cells. In addition, the size and geometry of the islands were shown to control Cell Shape. Traditional approaches to modulate Cell Shape, either by attaching suspended Cells to microbeads of different sizes or by plating Cells on substrates coated with different densities of ECM, suggested that Cell Shape may play an important role in control of apoptosis as well as growth. Data are presented which show how micropatterned substrates were used to definitively test this hypothesis. Progressively restricting bovine and human endothelial Cell extension by culturing Cells on smaller and smaller micropatterned adhesive islands regulated a transition from growth to apoptosis on a single continuum of Cell spreading, thus confirming the central role of Cell Shape in Cell function. The micropatterning technology is therefore essential not only for construction of biosurface devices but also for the investigation of the fundamental biology of Cell-ECM interactions.
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Cell Shape cytoskeletal mechanics and Cell cycle control in angiogenesis
Journal of Biomechanics, 1995Co-Authors: Donald E Ingber, Deepa Prusty, Zhengqi Sun, Hannah Betensky, Ning WangAbstract:Capillary endothelial Cells can be switched between growth and differentiation by altering Cell-extraCellular matrix interactions and thereby, modulating Cell Shape. Studies were carried out to determine when Cell Shape exerts its growth-regulatory influence during Cell cycle progression and to explore the role of cytoskeletal structure and mechanics in this control mechanism. When G0-synchronized Cells were cultured in basic fibroblast growth factor (FGF)-containing defined medium on dishes coated with increasing densities of fibronectin or a synthetic integrin ligand (RGD-containing peptide), Cell spreading, nuclear extension, and DNA synthesis all increased in parallel. To determine the minimum time Cells must be adherent and spread on extraCellular matrix (ECM) to gain entry into S phase, Cells were removed with trypsin or induced to retract using cytochalasin D at different times after plating. Both approaches revealed that Cells must remain extended for approximately 12-15 h and hence, most of G1, in order to enter S phase. After this restriction point was passed, normally 'anchorage-dependent' endothelial Cells turned on DNA synthesis even when round and in suspension. The importance of actin-containing microfilaments in Shape-dependent growth control was confirmed by culturing Cells in the presence of cytochalasin D (25-1000 ng ml-1): dose-dependent inhibition of Cell spreading, nuclear extension, and DNA synthesis resulted. In contrast, induction of microtubule disassembly using nocodazole had little effect on Cell or nuclear spreading and only partially inhibited DNA synthesis. Interestingly, combination of nocodazole with a suboptimal dose of cytochalasin D (100 ng ml-1) resulted in potent inhibition of both spreading and growth, suggesting that microtubules are redundant structural elements which can provide critical load-bearing functions when microfilaments are partially compromised. Similar synergism between nocodazole and cytochalasin D was observed when cytoskeletal stiffness was measured directly in living Cells using magnetic twisting cytometry. These results emphasize the importance of matrix-dependent changes in Cell and nuclear Shape as well as higher order structural interactions between different cytoskeletal filament systems for control of capillary Cell growth during angiogenesis.
Antoine Vigouroux - One of the best experts on this subject based on the ideXlab platform.
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class a penicillin binding proteins do not contribute to Cell Shape but repair Cell wall defects
eLife, 2020Co-Authors: Antoine Vigouroux, Baptiste Cordier, Andrey Aristov, Laura Alvarez, Gizem Ozbaykal, Thibault Chaze, Enno R Oldewurtel, Mariette MatondoAbstract:Cell Shape and Cell-envelope integrity of bacteria are determined by the peptidoglycan Cell wall. In rod-Shaped Escherichia coli, two conserved sets of machinery are essential for Cell-wall inserti ...
Mariette Matondo - One of the best experts on this subject based on the ideXlab platform.
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class a penicillin binding proteins do not contribute to Cell Shape but repair Cell wall defects
eLife, 2020Co-Authors: Antoine Vigouroux, Baptiste Cordier, Andrey Aristov, Laura Alvarez, Gizem Ozbaykal, Thibault Chaze, Enno R Oldewurtel, Mariette MatondoAbstract:Cell Shape and Cell-envelope integrity of bacteria are determined by the peptidoglycan Cell wall. In rod-Shaped Escherichia coli, two conserved sets of machinery are essential for Cell-wall inserti ...
Gizem Ozbaykal - One of the best experts on this subject based on the ideXlab platform.
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class a penicillin binding proteins do not contribute to Cell Shape but repair Cell wall defects
eLife, 2020Co-Authors: Antoine Vigouroux, Baptiste Cordier, Andrey Aristov, Laura Alvarez, Gizem Ozbaykal, Thibault Chaze, Enno R Oldewurtel, Mariette MatondoAbstract:Cell Shape and Cell-envelope integrity of bacteria are determined by the peptidoglycan Cell wall. In rod-Shaped Escherichia coli, two conserved sets of machinery are essential for Cell-wall inserti ...