Michael P Sheetz

Columbia University, New York, New York, United States

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Publications (344)3407.58 Total impact

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    ABSTRACT: Cells test the rigidity of the extracellular matrix by applying forces to it through integrin adhesions. Recent measurements show that these forces are applied by local micrometre-scale contractions, but how contraction force is regulated by rigidity is unknown. Here we performed high temporal- and spatial-resolution tracking of contractile forces by plating cells on sub-micrometre elastomeric pillars. We found that actomyosin-based sarcomere-like contractile units (CUs) simultaneously moved opposing pillars in net steps of ∼2.5 nm, independent of rigidity. What correlated with rigidity was the number of steps taken to reach a force level that activated recruitment of α-actinin to the CUs. When we removed actomyosin restriction by depleting tropomyosin 2.1, we observed larger steps and higher forces that resulted in aberrant rigidity sensing and growth of non-transformed cells on soft matrices. Thus, we conclude that tropomyosin 2.1 acts as a suppressor of growth on soft matrices by supporting proper rigidity sensing.
    No preview · Article · Nov 2015 · Nature Cell Biology
  • Rishita Changede · Xiaochun Xu · Felix Margadant · Michael P. Sheetz
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    ABSTRACT: Integrin adhesions assemble and mature in response to ligand binding and mechanical factors, but the molecular-level organization is not known. We report that ∼100-nm clusters of ∼50 β3-activated integrins form very early adhesions under a wide variety of conditions on RGD surfaces. These adhesions form similarly on fluid and rigid substrates, but most adhesions are transient on rigid substrates. Without talin or actin polymerization, few early adhesions form, but expression of either the talin head or rod domain in talin-depleted cells restores early adhesion formation. Mutation of the integrin binding site in the talin rod decreases cluster size. We suggest that the integrin clusters constitute universal early adhesions and that they are the modular units of cell matrix adhesions. They require the association of activated integrins with cytoplasmic proteins, in particular talin and actin, and cytoskeletal contraction on them causes adhesion maturation for cell motility and growth.
    No preview · Article · Nov 2015 · Developmental Cell
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    ABSTRACT: The turnover of integrin receptors is critical for cell migration and adhesion dynamics. Here we find that force development at integrins regulates adaptor protein recruitment and endocytosis. Using mobile RGD (Arg-Gly-Asp) ligands on supported lipid membranes (RGD membranes) and rigid RGD ligands on glass (RGD-glass), we find that matrix force-dependent integrin signals block endocytosis. Dab2, an adaptor protein of clathrin-mediated endocytosis, is not recruited to activated integrin-beta3 clusters on RGD-glass; however, it is recruited to integrin-mediated adhesions on RGD membranes. Further, when force generation is inhibited on RGD-glass, Dab2 binds to integrin-beta3 clusters. Dab2 binding to integrin-beta3 excludes other adhesion-related adaptor proteins, such as talin. The clathrin-mediated endocytic machinery combines with Dab2 to facilitate the endocytosis of RGD-integrin-beta3 clusters. From these observations, we propose that loss of traction force on ligand-bound integrin-beta3 causes recruitment of Dab2/clathrin, resulting in endocytosis of integrins.
    No preview · Article · Oct 2015 · Nature Communications
  • G V Shivashankar · Michael Sheetz · Paul Matsudaira

    No preview · Article · Sep 2015 · Integrative Biology
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    ABSTRACT: The formation of the immunological synapse between a T-cell and the antigen-presenting cell (APC) is critically dependent on actin dynamics, downstream of T-cell receptor (TCR) and integrin (LFA-1) signalling. There is also accumulating evidence that mechanical forces, generated by actin polymerization and/or myosin contractility regulate T-cell signalling. Because both receptor pathways are intertwined, their contributions towards the cytoskeletal organization remain elusive. Here, we identify the specific roles of TCR and LFA-1 by using a combination of micropatterning to spatially separate signalling systems and nanopillar arrays for high-precision analysis of cellular forces. We identify that Arp2/3 acts downstream of TCRs to nucleate dense actin foci but propagation of the network requires LFA-1 and the formin FHOD1. LFA-1 adhesion enhances actomyosin forces, which in turn modulate actin assembly downstream of the TCR. Together our data shows a mechanically cooperative system through which ligands presented by an APC modulate T-cell activation.
    Full-text · Article · Jul 2015 · Integrative Biology
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    ABSTRACT: In the body, soft tissues often undergo cycles of stretching and relaxation that may affect cell behaviour without changing matrix rigidity. To determine whether transient forces can substitute for a rigid matrix, we stretched soft pillar arrays. Surprisingly, 1-5% cyclic stretching over a frequency range of 0.01-10 Hz caused spreading and stress fibre formation (optimum 0.1 Hz) that persisted after 4 h of stretching. Similarly, stretching increased cell growth rates on soft pillars comparative to rigid substrates. Of possible factors linked to fibroblast growth, MRTF-A (myocardin-related transcription factor-A) moved to the nucleus in 2 h of cyclic stretching and reversed on cessation; but YAP (Yes-associated protein) moved much later. Knockdown of either MRTF-A or YAP blocked stretch-dependent growth. Thus, we suggest that the repeated pulling from a soft matrix can substitute for a stiff matrix in stimulating spreading, stress fibre formation and growth.
    Full-text · Article · Feb 2015 · Nature Communications

  • No preview · Article · Jan 2015 · Biophysical Journal
  • Haguy Wolfenson · Thomas Iskratsch · Michael P Sheetz
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    ABSTRACT: In this review, we focus on the early events in the process of fibroblast spreading on fibronectin matrices of different rigidities. We present a focused position piece that illustrates the many different tests that a cell makes of its environment before it establishes mature matrix adhesions. When a fibroblast is placed on fibronectin-coated glass surfaces at 37°C, it typically spreads and polarizes within 20-40 min primarily through αvβ3 integrin binding to fibronectin. In that short period, the cell goes through three major phases that involve binding, integrin activation, spreading, and mechanical testing of the surface. The advantage of using the model system of cell spreading from the unattached state is that it is highly reproducible and the stages that the cell undergoes can thus be studied in a highly quantitative manner, in both space and time. The mechanical and biochemical parameters that matter in this example are often surprising because of both the large number of tests that occur and the precision of the tests. We discuss our current understanding of those tests, the decision tree that is involved in this process, and an extension to the behavior of the cells at longer time periods when mature adhesions develop. Because many other matrices and integrins are involved in cell-matrix adhesion, this model system gives us a limited view of a subset of cellular behaviors that can occur. However, by defining one cellular process at a molecular level, we know more of what to expect when defining other processes. Because each cellular process will involve some different proteins, a molecular understanding of multiple functions operating within a given cell can lead to strategies to selectively block a function. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.
    No preview · Article · Dec 2014 · Biophysical Journal
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    Michael P Sheetz
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    ABSTRACT: At a time of historically low National Institutes of Health funding rates and many problems with the conduct of research (unfunded mandates, disgruntled reviewers, and rampant paranoia), there is a concern that biomedical research as a profession is waning in the United States (see "Rescuing US biomedical research from its systemic flaws" by Alberts and colleagues in the Proceedings of the National Academy of Sciences). However, it is wonderful to discover something new and to tackle tough puzzles. If we could focus more of our effort on discussing scientific problems and doing research, then we could be more productive and perhaps happier. One potential solution is to focus efforts on small thematic institutes in the university structure that can provide a stimulating and supportive environment for innovation and exploration. With an open-lab concept, there are economies of scale that can diminish paperwork and costs, while providing greater access to state-of-the-art equipment. Merging multiple disciplines around a common theme can catalyze innovation, and this enables individuals to develop new concepts without giving up the credit they deserve, because it is usually clear who did the work. Small institutes do not solve larger systemic problems but rather enable collective efforts to address the noisome aspects of the system and foster an innovative community effort to address scientific problems.
    Preview · Article · Nov 2014 · Molecular Biology of the Cell
  • Thomas Iskratsch · Haguy Wolfenson · Michael P Sheetz
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    ABSTRACT: Although the shapes of organisms are encoded in their genome, the developmental processes that lead to the final form of vertebrates involve a constant feedback between dynamic mechanical forces, and cell growth and motility. Mechanobiology has emerged as a discipline dedicated to the study of the effects of mechanical forces and geometry on cell growth and motility - for example, during cell-matrix adhesion development - through the signalling process of mechanotransduction.
    No preview · Article · Oct 2014 · Nature Reviews Molecular Cell Biology
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    ABSTRACT: Neisseria gonorrheae bacteria are the causative agent of the second most common sexually transmitted infection in the world. The bacteria move on a surface by means of twitching motility. Their movement is mediated by multiple long and flexible filaments, called type IV pili, that extend from the cell body, attach to the surface, and retract, thus generating a pulling force. Moving cells also use pili to aggregate and form microcolonies. However, the mechanism by which the pili surrounding the cell body work together to propel bacteria remains unclear. Understanding this process will help describe the motility of N. gonorrheae bacteria, and thus the dissemination of the disease which they cause. In this article we track individual twitching cells and observe that their trajectories consist of alternating moving and pausing intervals, while the cell body is preferably oriented with its wide side toward the direction of motion. Based on these data, we propose a model for the collective pili operation of N. gonorrheae bacteria that explains the experimentally observed behavior. Individual pili function independently but can lead to coordinated motion or pausing via the force balance. The geometry of the cell defines its orientation during motion. We show that by changing pili substrate interactions, the motility pattern can be altered in a predictable way. Although the model proposed is tangibly simple, it still has sufficient robustness to incorporate further advanced pili features and various cell geometries to describe other bacteria that employ pili to move on surfaces.
    No preview · Article · Oct 2014 · Biophysical Journal
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    ABSTRACT: Organ size is controlled by the concerted action of biochemical and physical processes. Although mechanical forces are known to regulate cell and tissue behavior, as well as organogenesis, the precise molecular events that integrate mechanical and biochemical signals to control these processes are not fully known. The recently delineated Hippo-tumor suppressor network and its two nuclear effectors, YAP and TAZ, shed light on these mechanisms. YAP and TAZ are proto-oncogene proteins that respond to complex physical milieu represented by the rigidity of the extracellular matrix, cell geometry, cell density, cell polarity and the status of the actin cytoskeleton. Here, we review the current knowledge of how YAP and TAZ function as mechanosensors and mechanotransducers. We also suggest that by deciphering the mechanical and biochemical signals controlling YAP/ TAZ function, we will gain insights into new strategies for cancer treatment and organ regeneration.
    Full-text · Article · Apr 2014 · FEBS letters
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    Mingxi Yao · Benjamin T Goult · Hu Chen · Peiwen Cong · Michael P Sheetz · Jie Yan
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    ABSTRACT: The force-dependent interaction between talin and vinculin plays a crucial role in the initiation and growth of focal adhesions. Here we use magnetic tweezers to characterise the mechano-sensitive compact N-terminal region of the talin rod, and show that the three helical bundles R1-R3 in this region unfold in three distinct steps consistent with the domains unfolding independently. Mechanical stretching of talin R1-R3 enhances its binding to vinculin and vinculin binding inhibits talin refolding after force is released. Mutations that stabilize R3 identify it as the initial mechano-sensing domain in talin, unfolding at ∼5 pN, suggesting that 5 pN is the force threshold for vinculin binding and adhesion progression.
    Full-text · Article · Apr 2014 · Scientific Reports
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    Jie Yan · Mingxi Yao · Benjamin T. Goult · Michael P. Sheetz
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    ABSTRACT: A fundamental question in mechanobiology is how mechanical stimuli are sensed by mechanosensing proteins and converted into signals that direct cells to adapt to the external environment. A key function of cell adhesion to the extracellular matrix (ECM) is to transduce mechanical forces between cells and their extracellular environment. Talin, a cytoplasmic adapter essential for integrin-mediated adhesion to the ECM, links the actin cytoskeleton to integrin at the plasma membrane. Here, we review recent progress in the understanding of talin-dependent mechanosensing revealed by stretching single talin molecules. Rapid progress in single-molecule force manipulation technologies has made it possible to directly study the impact of mechanical force on talin’s conformations and its interactions with other signaling proteins. We also provide our views on how findings from such studies may bring new insights into understanding the principles of mechanobiology on a broader scale, and how such fundamental knowledge may be harnessed for mechanopharmacology.
    Full-text · Article · Mar 2014 · Cellular and Molecular Bioengineering
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    Xian Zhang · Simon W Moore · Thomas Iskratsch · Michael P Sheetz
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    ABSTRACT: Tyrosine phosphorylation of the substrate domain of Cas (CasSD) correlates with increased cell migration in healthy and diseased cells. Here we address the mechanism leading to CasSD phosphorylation in the context of fibronectin-induced early spreading of fibroblasts. We previously demonstrated that mechanical stretching of CasSD exposes phosphorylation sites for Src family kinases (SFKs). Surprisingly, phosphorylation of CasSD was independent of myosin contractile activity, but dependent on actin polymerization. Further, we found that CasSD phosphorylation in early cell spreading required: (1) integrin anchorage and integrin-mediated SFK activation, (2) association of Cas with focal adhesion kinase (FAK) and (3) N-WASP actin assembly activity. These findings and analyses of Cas domain interactions indicate that Cas N-terminus associates with FAK/N-WASP complex at the cell's protrusive edge and that Cas C-terminus associates with immobilized integrin-SFK cluster. Thus, extension of the leading edge by actin polymerization could stretch Cas in early cell spreading, priming it for phosphorylation.
    Preview · Article · Jan 2014 · Journal of Cell Science
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    Preview · Article · Jan 2014 · Biophysical Journal
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    Rishita Changede · Felix Margadant · Michael P. Sheetz

    Preview · Article · Jan 2014 · Biophysical Journal
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    Preview · Article · Jan 2014 · Biophysical Journal
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    Preview · Article · Jan 2014 · Biophysical Journal
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    Michael Sheetz

    Preview · Article · Jan 2014 · Biophysical Journal

Publication Stats

34k Citations
3,407.58 Total Impact Points

Institutions

  • 1970-2015
    • Columbia University
      • Department of Biological Sciences
      New York, New York, United States
  • 2013
    • IBEC Institute for Bioengineering of Catalonia
      Barcino, Catalonia, Spain
  • 2012-2013
    • National University of Singapore
      Tumasik, Singapore
  • 2007
    • CUNY Graduate Center
      New York, New York, United States
  • 2006
    • Michigan State University
      • Department of Zoology
      East Lansing, MI, United States
  • 1991-2002
    • Duke University Medical Center
      • Department of Cell Biology
      Durham, North Carolina, United States
    • University of California, San Francisco
      San Francisco, California, United States
  • 1992-2000
    • Duke University
      • • Department of Mechanical Engineering and Materials Science (MEMS)
      • • Department of Medicine
      Durham, North Carolina, United States
  • 1995
    • Albert Einstein College of Medicine
      • Department of Physiology & Biophysics
      New York, New York, United States
    • Vanderbilt University
      Нашвилл, Michigan, United States
  • 1993
    • University of Illinois, Urbana-Champaign
      Urbana, Illinois, United States
  • 1986-1993
    • Washington University in St. Louis
      • • Department of Cell Biology and Physiology
      • • Department of Medicine
      San Luis, Missouri, United States
  • 1989
    • Yale University
      New Haven, Connecticut, United States
  • 1987
    • University of Colorado at Boulder
      • Department of Molecular, Cellular, and Developmental Biology (MCDB)
      Boulder, Colorado, United States
  • 1985
    • Barrow Neurological Institute
      Phoenix, Arizona, United States
  • 1983
    • Stanford Medicine
      • Department of Structural Biology
      Stanford, California, United States
  • 1980
    • UConn Health Center
      Farmington, Connecticut, United States
  • 1976
    • University of California, San Diego
      San Diego, California, United States
  • 1972-1974
    • California Institute of Technology
      • Arthur Amos Noyes Laboratory of Chemical Physics
      Pasadena, California, United States