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Chirasani VR, Khan MAI, Malavade JN, Dokholyan NV, Hoffman BD, Campbell SL. Molecular basis and cellular functions of vinculin-actin directional catch bonding. Nat Commun 2023; 14:8300. [PMID: 38097542 PMCID: PMC10721916 DOI: 10.1038/s41467-023-43779-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 11/20/2023] [Indexed: 12/17/2023] Open
Abstract
The ability of cells and tissues to respond differentially to mechanical forces applied in distinct directions is mediated by the ability of load-bearing proteins to preferentially maintain physical linkages in certain directions. However, the molecular basis and biological consequences of directional force-sensitive binding remain unclear. Vinculin (Vcn) is a load-bearing linker protein that exhibits directional catch bonding due to interactions between the Vcn tail domain (Vt) and filamentous (F)-actin. We developed a computational approach to predict Vcn residues involved in directional catch bonding and produced a set of associated Vcn variants with unaltered Vt structure, actin binding, or phospholipid interactions. Incorporation of the variants did not affect Vcn activation but reduced Vcn loading and altered exchange dynamics, consistent with the loss of directional catch bonding. Expression of Vcn variants perturbed the coordination of subcellular structures and cell migration, establishing key cellular functions for Vcn directional catch bonding.
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Affiliation(s)
- Venkat R Chirasani
- Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Mohammad Ashhar I Khan
- Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Juilee N Malavade
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Nikolay V Dokholyan
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA, USA.
- Department of Biochemistry & Molecular Biology, Penn State College of Medicine, Hershey, PA, USA.
- Department of Chemistry, Penn State College of Medicine, Hershey, PA, USA.
| | - Brenton D Hoffman
- Department of Biomedical Engineering, Duke University, Durham, NC, USA.
- Department of Cell Biology, Duke University, Durham, NC, USA.
| | - Sharon L Campbell
- Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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2
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Chirasani VR, Khan MAI, Malavade JN, Dokholyan NV, Hoffman BD, Campbell SL. Elucidation of the Molecular Basis and Cellular Functions of Vinculin-Actin Directional Catch Bonding. RESEARCH SQUARE 2023:rs.3.rs-2334490. [PMID: 36711743 PMCID: PMC9882595 DOI: 10.21203/rs.3.rs-2334490/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The ability of cells and tissues to differentially resist or adapt to mechanical forces applied in distinct directions is mediated by the ability of load-bearing proteins to preferentially maintain physical linkages in certain directions. However, the molecular basis and biological consequences of directional force-sensitive binding are unclear. Vinculin (Vcn) is a load-bearing linker protein that exhibits directional catch bonding due to interactions between the Vcn tail domain (Vt) and filamentous (F)-actin. We developed a computational approach to predict Vcn residues involved in directional catch bonding and produced a set of associated Vcn variants with unaltered Vt structure, actin binding, or phospholipid interactions. Incorporation of these variants into Vcn biosensors did not perturb Vcn conformation, but reduced Vcn loading consistent with loss of directional catch bonding. Expression of Vcn variants perturbed the coalignment of FAs and F-actin and directed cell migration, establishing key cellular functions for Vcn directional catch bonding.
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Affiliation(s)
- Venkat R. Chirasani
- Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Mohammad Ashhar I. Khan
- Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | | | - Nikolay V. Dokholyan
- Department of Pharmacology, Department of Biochemistry & Molecular Biology, Department of Chemistry, Penn State College of Medicine, Hershey, PA, USA
| | - Brenton D. Hoffman
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
- Department of Cell Biology, Duke University, Durham, NC, USA
| | - Sharon L. Campbell
- Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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3
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Le Coq J, Acebrón I, Rodrigo Martin B, López Navajas P, Lietha D. New insights into FAK structure and function in focal adhesions. J Cell Sci 2022; 135:277381. [PMID: 36239192 DOI: 10.1242/jcs.259089] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Focal adhesion kinase (FAK; also known as PTK2) was discovered three decades ago and is now recognised as a key player in the regulation of cell-matrix adhesion and mesenchymal cell migration. Although it is essential during development, FAK also drives invasive cancer progression and metastasis. On a structural level, the basic building blocks of FAK have been described for some time. However, a picture of how FAK integrates into larger assemblies in various cellular environments, including one of its main cellular locations, the focal adhesion (FA) complex, is only beginning to emerge. Nano-resolution data from cellular studies, as well as atomic structures from reconstituted systems, have provided first insights, but also point to challenges that remain for obtaining a full structural understanding of how FAK is integrated in the FA complex and the structural changes occurring at different stages of FA maturation. In this Review, we discuss the known structural features of FAK, the interactions with its partners within the FA environment on the cell membrane and propose how its initial assembly in nascent FAs might change during FA maturation under force.
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Affiliation(s)
- Johanne Le Coq
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), 28029 Madrid, Spain
| | - Iván Acebrón
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), 28029 Madrid, Spain
| | - Bárbara Rodrigo Martin
- Structural and Chemical Biology, Margarita Salas Center for Biological Research (CIB), Spanish National Research Council (CSIC), 28040 Madrid, Spain
| | - Pilar López Navajas
- Structural and Chemical Biology, Margarita Salas Center for Biological Research (CIB), Spanish National Research Council (CSIC), 28040 Madrid, Spain
| | - Daniel Lietha
- Structural and Chemical Biology, Margarita Salas Center for Biological Research (CIB), Spanish National Research Council (CSIC), 28040 Madrid, Spain
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Braun L, Schoen I, Vogel V. PIP 2-induced membrane binding of the vinculin tail competes with its other binding partners. Biophys J 2021; 120:4608-4622. [PMID: 34411575 DOI: 10.1016/j.bpj.2021.08.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 06/14/2021] [Accepted: 08/11/2021] [Indexed: 01/09/2023] Open
Abstract
Vinculin plays a key role during the first phase of focal adhesion formation and interacts with the plasma membrane through specific binding of its tail domain to the lipid phosphatidylinositol 4,5-bisphosphate (PIP2). Our understanding of the PIP2-vinculin interaction has been hampered by contradictory biochemical and structural data. Here, we used a multiscale molecular dynamics simulation approach, in which unbiased coarse-grained molecular dynamics were used to generate starting structures for subsequent microsecond-long all-atom simulations. This allowed us to map the interaction of the vinculin tail with PIP2-enriched membranes in atomistic detail. In agreement with experimental data, we have shown that membrane binding is sterically incompatible with the intramolecular interaction between vinculin's head and tail domain. Our simulations further confirmed biochemical and structural results, which identified two positively charged surfaces, the basic collar and the basic ladder, as the main PIP2 interaction sites. By introducing a valency-disaggregated binding network analysis, we were able to map the protein-lipid interactions in unprecedented detail. In contrast to the basic collar, in which PIP2 is specifically recognized by an up to hexavalent binding pocket, the basic ladder forms a series of low-valency binding sites. Importantly, many of these PIP2 binding residues are also involved in maintaining vinculin in a closed, autoinhibited conformation. These findings led us to propose a molecular mechanism for the coupling between vinculin activation and membrane binding. Finally, our refined binding site suggests an allosteric relationship between PIP2 and F-actin binding that disfavors simultaneous interaction with both ligands, despite nonoverlapping binding sites.
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Affiliation(s)
- Lukas Braun
- Laboratory of Applied Mechanobiology, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland.
| | - Ingmar Schoen
- School of Pharmacy and Biomolecular Sciences, Irish Centre for Vascular Biology, Royal College of Surgeons in Ireland, Dublin 2, Ireland
| | - Viola Vogel
- Laboratory of Applied Mechanobiology, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
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Lietha D, Izard T. Roles of Membrane Domains in Integrin-Mediated Cell Adhesion. Int J Mol Sci 2020; 21:ijms21155531. [PMID: 32752284 PMCID: PMC7432473 DOI: 10.3390/ijms21155531] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/29/2020] [Accepted: 07/31/2020] [Indexed: 12/13/2022] Open
Abstract
The composition and organization of the plasma membrane play important functional and regulatory roles in integrin signaling, which direct many physiological and pathological processes, such as development, wound healing, immunity, thrombosis, and cancer metastasis. Membranes are comprised of regions that are thick or thin owing to spontaneous partitioning of long-chain saturated lipids from short-chain polyunsaturated lipids into domains defined as ordered and liquid-disorder domains, respectively. Liquid-ordered domains are typically 100 nm in diameter and sometimes referred to as lipid rafts. We posit that integrin β senses membrane thickness and that mechanical force on the membrane regulates integrin activation through membrane thinning. This review examines what we know about the nature and mechanism of the interaction of integrins with the plasma membrane and its effects on regulating integrins and its binding partners.
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Affiliation(s)
- Daniel Lietha
- Cell Signaling and Adhesion Group, Structural and Chemical Biology, Margarita Salas Center for Biological Research (CIB-CSIC), E-28040 Madrid, Spain;
| | - Tina Izard
- Cell Adhesion Laboratory, Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, FL 33458, USA
- Correspondence:
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Kelley CF, Litschel T, Schumacher S, Dedden D, Schwille P, Mizuno N. Phosphoinositides regulate force-independent interactions between talin, vinculin, and actin. eLife 2020; 9:e56110. [PMID: 32657269 PMCID: PMC7384861 DOI: 10.7554/elife.56110] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 07/10/2020] [Indexed: 12/25/2022] Open
Abstract
Focal adhesions (FA) are large macromolecular assemblies which help transmit mechanical forces and regulatory signals between the extracellular matrix and an interacting cell. Two key proteins talin and vinculin connecting integrin to actomyosin networks in the cell. Both proteins bind to F-actin and each other, providing a foundation for network formation within FAs. However, the underlying mechanisms regulating their engagement remain unclear. Here, we report on the results of in vitro reconstitution of talin-vinculin-actin assemblies using synthetic membrane systems. We find that neither talin nor vinculin alone recruit actin filaments to the membrane. In contrast, phosphoinositide-rich membranes recruit and activate talin, and the membrane-bound talin then activates vinculin. Together, the two proteins then link actin to the membrane. Encapsulation of these components within vesicles reorganized actin into higher-order networks. Notably, these observations were made in the absence of applied force, whereby we infer that the initial assembly stage of FAs is force independent. Our findings demonstrate that the local membrane composition plays a key role in controlling the stepwise recruitment, activation, and engagement of proteins within FAs.
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Affiliation(s)
- Charlotte F Kelley
- Max Planck Institute of Biochemistry, Department of Structural Cell BiologyMartinsriedGermany
| | - Thomas Litschel
- Max Planck Institute of Biochemistry, Department of Cellular and Molecular BiophysicsMartinsriedGermany
| | - Stephanie Schumacher
- Max Planck Institute of Biochemistry, Department of Structural Cell BiologyMartinsriedGermany
| | - Dirk Dedden
- Max Planck Institute of Biochemistry, Department of Structural Cell BiologyMartinsriedGermany
| | - Petra Schwille
- Max Planck Institute of Biochemistry, Department of Cellular and Molecular BiophysicsMartinsriedGermany
| | - Naoko Mizuno
- Max Planck Institute of Biochemistry, Department of Structural Cell BiologyMartinsriedGermany
- Laboratory of Structural Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of HealthBethesdaUnited States
- National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of HealthBethesdaUnited States
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Sarker M, Goliaei A, Golesi F, Poggi M, Cook A, Khan MAI, Temple BR, Stefanini L, Canault M, Bergmeier W, Campbell SL. Subcellular localization of Rap1 GTPase activator CalDAG-GEFI is orchestrated by interaction of its atypical C1 domain with membrane phosphoinositides. J Thromb Haemost 2020; 18:693-705. [PMID: 31758832 PMCID: PMC7050387 DOI: 10.1111/jth.14687] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 10/17/2019] [Accepted: 11/14/2019] [Indexed: 12/21/2022]
Abstract
BACKGROUND The small GTPase Rap1 and its guanine nucleotide exchange factor, CalDAG-GEFI (CDGI), are critical for platelet function and hemostatic plug formation. CDGI function is regulated by a calcium binding EF hand regulatory domain and an atypical C1 domain with unknown function. OBJECTIVE Here, we investigated whether the C1 domain controls CDGI subcellular localization, both in vitro and in vivo. METHODS CDGI interaction with phosphoinositides was studied by lipid co-sedimentation assays and molecular dynamics simulations. Cellular localization of CDGI was studied in heterologous cells by immunofluorescence and subcellular fractionation assays. RESULTS Lipid co-sedimentation studies demonstrated that the CDGI C1 domain associates with membranes through exclusive recognition of phosphoinositides, phosphatidylinositol (4,5)-biphosphate (PIP2) and phosphatidylinositol (3,4,5)-triphosphate (PIP3). Molecular dynamics simulations identified a phospholipid recognition motif consisting of residues exclusive to the CDGI C1 domain. Mutation of those residues abolished co-sedimentation of the C1 domain with lipid vesicles and impaired membrane localization of CDGI in heterologous cells. CONCLUSION Our studies identify a novel interaction between an atypical C1 domain and phosphatidylinositol (4,5)-biphosphate and phosphatidylinositol (3,4,5)-triphosphate in cellular membranes, which is critical for Rap1 signaling in health and disease.
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Affiliation(s)
- Muzaddid Sarker
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Ardeshir Goliaei
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | | | - Marjorie Poggi
- Aix Marseille University, INSERM, INRA, Marseille, France
| | - Aaron Cook
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Mohammad A. I. Khan
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Brenda R. Temple
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- RL Juliano Structural Bioinformatics Core, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Lucia Stefanini
- Department of Internal Medicine and Medical Specialties, Sapienza University of Rome, Rome, Italy
| | | | - Wolfgang Bergmeier
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Sharon L. Campbell
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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The membrane environment of cadherin adhesion receptors: a working hypothesis. Biochem Soc Trans 2019; 47:985-995. [DOI: 10.1042/bst20180012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 06/09/2019] [Accepted: 06/11/2019] [Indexed: 11/17/2022]
Abstract
Abstract
Classical cadherin cell adhesion receptors are integral membrane proteins that mediate cell–cell interactions, tissue integrity and morphogenesis. Cadherins are best understood to function as membrane-spanning molecular composites that couple adhesion to the cytoskeleton. On the other hand, the membrane lipid environment of the cadherins is an under-investigated aspect of their cell biology. In this review, we discuss two lines of research that show how the membrane can directly or indirectly contribute to cadherin function. Firstly, we consider how modification of its local lipid environment can potentially influence cadherin signalling, adhesion and dynamics, focusing on a role for phosphoinositide-4,5-bisphosphate. Secondly, we discuss how caveolae may indirectly regulate cadherins by modifying either the lipid composition and/or mechanical tension of the plasma membrane. Thus, we suggest that the membrane is a frontier of cadherin biology that is ripe for re-exploration.
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Ijuin T. Phosphoinositide phosphatases in cancer cell dynamics-Beyond PI3K and PTEN. Semin Cancer Biol 2019; 59:50-65. [PMID: 30922959 DOI: 10.1016/j.semcancer.2019.03.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 03/18/2019] [Accepted: 03/18/2019] [Indexed: 12/16/2022]
Abstract
Phosphoinositides are a group of lipids that regulate intracellular signaling and subcellular biological events. The signaling by phosphatidylinositol-3,4,5-trisphosphate and Akt mediates the action of growth factors that are essential for cell proliferation, gene transcription, cell migration, and polarity. The hyperactivation of this signaling has been identified in different cancer cells; and, it has been implicated in oncogenic transformation and cancer cell malignancy. Recent studies have argued the role of phosphoinositides in cancer cell dynamics, including actin cytoskeletal rearrangement at the plasma membrane and the organization of intracellular compartments. The focus of this review is to summarize the impact of the activities of phosphoinositide phosphatases on intracellular signaling related to cancer cell dynamics and to discuss how the abnormalities in the activities of the enzymes alter the levels of phosphoinositides in cancer cells.
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Affiliation(s)
- Takeshi Ijuin
- Division of Biochemistry, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Chu-o, Kobe 650-0017, Japan.
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Bhagavat R, Sankar S, Srinivasan N, Chandra N. An Augmented Pocketome: Detection and Analysis of Small-Molecule Binding Pockets in Proteins of Known 3D Structure. Structure 2019. [PMID: 29514079 DOI: 10.1016/j.str.2018.02.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Protein-ligand interactions form the basis of most cellular events. Identifying ligand binding pockets in proteins will greatly facilitate rationalizing and predicting protein function. Ligand binding sites are unknown for many proteins of known three-dimensional (3D) structure, creating a gap in our understanding of protein structure-function relationships. To bridge this gap, we detect pockets in proteins of known 3D structures, using computational techniques. This augmented pocketome (PocketDB) consists of 249,096 pockets, which is about seven times larger than what is currently known. We deduce possible ligand associations for about 46% of the newly identified pockets. The augmented pocketome, when subjected to clustering based on similarities among pockets, yielded 2,161 site types, which are associated with 1,037 ligand types, together providing fold-site-type-ligand-type associations. The PocketDB resource facilitates a structure-based function annotation, delineation of the structural basis of ligand recognition, and provides functional clues for domains of unknown functions, allosteric proteins, and druggable pockets.
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Affiliation(s)
- Raghu Bhagavat
- National Mathematics Initiative, Indian Institute of Science, Bangalore 560012, India
| | - Santhosh Sankar
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Narayanaswamy Srinivasan
- National Mathematics Initiative, Indian Institute of Science, Bangalore 560012, India; Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| | - Nagasuma Chandra
- National Mathematics Initiative, Indian Institute of Science, Bangalore 560012, India; Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India.
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12
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Goldmann WH. Molecular interactions between vinculin and phospholipids. Cell Biol Int 2018; 42:1076-1078. [PMID: 29696730 DOI: 10.1002/cbin.10978] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2018] [Accepted: 04/21/2018] [Indexed: 01/13/2023]
Abstract
The focal adhesion protein vinculin has been implicated in associating with soluble and membranous phospholipids. Detailed investigations over the past ten years describe the intermolecular interactions of the vinculin tail domain with soluble and membrane phospholipids. Previous studies have implied that the tail's unstructured C-terminal region affects the mechanical behavior of cells and that the same region, at the molecular level, has bi-stable behavior sensitive to different protonation states. The aim of this short communication is to discuss whether the C-terminal vinculin tail (Vt) domain interacts favorably with membrane-embedded phospholipids such as PIP2 and that the region is also an anchor for lipid membranes.
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Affiliation(s)
- Wolfgang H Goldmann
- Department of Physics, Biophysics Group, Friedrich-Alexander-University Erlangen-Nuremberg, D-91052, Erlangen, Germany
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Wood MN, Ishiyama N, Singaram I, Chung CM, Flozak AS, Yemelyanov A, Ikura M, Cho W, Gottardi CJ. α-Catenin homodimers are recruited to phosphoinositide-activated membranes to promote adhesion. J Cell Biol 2017; 216:3767-3783. [PMID: 28874417 PMCID: PMC5674881 DOI: 10.1083/jcb.201612006] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 03/22/2017] [Accepted: 07/28/2017] [Indexed: 11/22/2022] Open
Abstract
A unique feature of α-catenin localized outside the cadherin-catenin complex is its capacity to form homodimers, but the subcellular localization and functions of this form of α-catenin remain incompletely understood. We identified a cadherin-free form of α-catenin that is recruited to the leading edge of migrating cells in a phosphatidylinositol 3-kinase-dependent manner. Surface plasmon resonance analysis shows that α-catenin homodimers, but not monomers, selectively bind phosphatidylinositol-3,4,5-trisphosphate-containing lipid vesicles with high affinity, where three basic residues, K488, K493, and R496, contribute to binding. Chemical-induced dimerization of α-catenin containing a synthetic dimerization domain promotes its accumulation within lamellipodia and elaboration of protrusions with extended filopodia, which are attenuated in the α-cateninKKR<3A mutant. Cells restored with a full-length, natively homodimerizing form of α-cateninKKR<3A display reduced membrane recruitment, altered epithelial sheet migrations, and weaker cell-cell adhesion compared with WT α-catenin. These findings show that α-catenin homodimers are recruited to phosphoinositide-activated membranes to promote adhesion and migration, suggesting that phosphoinositide binding may be a defining feature of α-catenin function outside the cadherin-catenin complex.
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Affiliation(s)
- Megan N Wood
- Department of Medicine, Northwestern University, Feinberg School of Medicine, Chicago, IL
- The Driskill Graduate Training Program in Life Sciences, Northwestern University, Feinberg School of Medicine, Chicago, IL
| | - Noboru Ishiyama
- Princess Margaret Cancer Centre, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Indira Singaram
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL
| | - Connie M Chung
- Department of Medicine, Northwestern University, Feinberg School of Medicine, Chicago, IL
| | - Annette S Flozak
- Department of Medicine, Northwestern University, Feinberg School of Medicine, Chicago, IL
| | - Alex Yemelyanov
- Department of Medicine, Northwestern University, Feinberg School of Medicine, Chicago, IL
- Department of Chemistry of Life Processes, Northwestern University, Feinberg School of Medicine, Chicago, IL
| | - Mitsu Ikura
- Princess Margaret Cancer Centre, University Health Network, University of Toronto, Toronto, ON, Canada
- Division of Signaling Biology, Ontario Cancer Institute, University of Toronto, Toronto, ON, Canada
| | - Wonhwa Cho
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL
- Department of Genetic Engineering, Kyung Hee University, Yongin, Republic of Korea
| | - Cara J Gottardi
- Department of Medicine, Northwestern University, Feinberg School of Medicine, Chicago, IL
- Department of Cellular and Molecular Biology, Northwestern University, Feinberg School of Medicine, Chicago, IL
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14
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Ackermann MA, King B, Lieberman NAP, Bobbili PJ, Rudloff M, Berndsen CE, Wright NT, Hecker PA, Kontrogianni-Konstantopoulos A. Novel obscurins mediate cardiomyocyte adhesion and size via the PI3K/AKT/mTOR signaling pathway. J Mol Cell Cardiol 2017; 111:27-39. [PMID: 28826662 PMCID: PMC5694667 DOI: 10.1016/j.yjmcc.2017.08.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 08/02/2017] [Accepted: 08/03/2017] [Indexed: 12/29/2022]
Abstract
The intercalated disc of cardiac muscle embodies a highly-ordered, multifunctional network, essential for the synchronous contraction of the heart. Over 200 known proteins localize to the intercalated disc. The challenge now lies in their characterization as it relates to the coupling of neighboring cells and whole heart function. Using molecular, biochemical and imaging techniques, we characterized for the first time two small obscurin isoforms, obscurin-40 and obscurin-80, which are enriched at distinct locations of the intercalated disc. Both proteins bind specifically and directly to select phospholipids via their pleckstrin homology (PH) domain. Overexpression of either isoform or the PH-domain in cardiomyocytes results in decreased cell adhesion and size via reduced activation of the PI3K/AKT/mTOR pathway that is intimately linked to cardiac hypertrophy. In addition, obscurin-80 and obscurin-40 are significantly reduced in acute (myocardial infarction) and chronic (pressure overload) murine cardiac-stress models underscoring their key role in maintaining cardiac homeostasis. Our novel findings implicate small obscurins in the maintenance of cardiomyocyte size and coupling, and the development of heart failure by antagonizing the PI3K/AKT/mTOR pathway.
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Affiliation(s)
- Maegen A Ackermann
- Department of Biochemistry and Molecular Biology, University of Maryland, School of Medicine, Baltimore, MD 21201, United States; Department of Physiology and Cell Biology, Wexner College of Medicine, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, United States.
| | - Brendan King
- Department of Biochemistry and Molecular Biology, University of Maryland, School of Medicine, Baltimore, MD 21201, United States
| | - Nicole A P Lieberman
- Department of Biochemistry and Molecular Biology, University of Maryland, School of Medicine, Baltimore, MD 21201, United States
| | - Prameela J Bobbili
- Department of Physiology and Cell Biology, Wexner College of Medicine, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, United States
| | - Michael Rudloff
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, VA 22807, United States
| | - Christopher E Berndsen
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, VA 22807, United States
| | - Nathan T Wright
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, VA 22807, United States
| | - Peter A Hecker
- Division of Cardiology and Department of Medicine, University of Maryland, Baltimore, MD 20201, United States
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15
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Dwivedi M, Winter R. Binding of Vinculin to Lipid Membranes in Its Inhibited and Activated States. Biophys J 2017; 111:1444-1453. [PMID: 27705767 DOI: 10.1016/j.bpj.2016.08.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 08/15/2016] [Accepted: 08/18/2016] [Indexed: 10/20/2022] Open
Abstract
Phosphoinositols are an important class of phospholipids that are involved in a myriad of cellular processes, from cell signaling to motility and adhesion. Vinculin (Vn) is a major adaptor protein that regulates focal adhesions in conjunction with PIP2 in lipid membranes and other cytoskeletal components. The binding and unbinding transitions of Vn at the membrane interface are an important link to understanding the coordination of cell signaling and motility. Using different biophysical tools, including atomic force microscopy combined with confocal fluorescence microscopy and Fourier transform infrared spectroscopy, we studied the nanoscopic interactions of activated and autoinhibited states of Vn with lipid membranes. We hypothesize that a weak interaction occurs between Vn and lipid membranes, which leads to binding of autoinhibited Vn to supported lipid bilayers, and to unbinding in freestanding lipid vesicles. Likely driving forces may include tethering of the C-terminus to the lipid membrane, as well as hydrophobic helix-membrane interactions. Conversely, activated Vn binds strongly to membranes through specific interactions with clusters of PIP2 embedded in lipid membranes. Activated Vn harbored on PIP2 clusters may form small oligomeric interaction platforms for further interaction partners, which is necessary for the proper function of focal adhesion points.
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Affiliation(s)
- Mridula Dwivedi
- Physical Chemistry I, Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, TU Dortmund University, Dortmund, Germany.
| | - Roland Winter
- Physical Chemistry I, Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, TU Dortmund University, Dortmund, Germany.
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16
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Zhou DW, Lee TT, Weng S, Fu J, García AJ. Effects of substrate stiffness and actomyosin contractility on coupling between force transmission and vinculin-paxillin recruitment at single focal adhesions. Mol Biol Cell 2017; 28:1901-1911. [PMID: 28468976 PMCID: PMC5541841 DOI: 10.1091/mbc.e17-02-0116] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 03/31/2017] [Accepted: 04/27/2017] [Indexed: 12/22/2022] Open
Abstract
The relationship between force and focal adhesion (FA) dynamics is unclear. Substrate stiffness and contractility regulate the relationship between force and vinculin, but not paxillin, turnover at FAs. Substrate stiffness and contractility also regulate whether vinculin and paxillin turnover dynamics are correlated at FAs. Focal adhesions (FAs) regulate force transfer between the cytoskeleton and ECM–integrin complexes. We previously showed that vinculin regulates force transmission at FAs. Vinculin residence time in FAs correlated with applied force, supporting a mechanosensitive model in which forces stabilize vinculin’s active conformation to promote force transfer. In the present study, we examined the relationship between traction force and vinculin–paxillin localization to single FAs in the context of substrate stiffness and actomyosin contractility. We found that vinculin and paxillin FA area did not correlate with traction force magnitudes at single FAs, and this was consistent across different ECM stiffness and cytoskeletal tension states. However, vinculin residence time at FAs varied linearly with applied force for stiff substrates, and this was disrupted on soft substrates and after contractility inhibition. In contrast, paxillin residence time at FAs was independent of local applied force and substrate stiffness. Paxillin recruitment and residence time at FAs, however, were dependent on cytoskeletal contractility on lower substrate stiffness values. Finally, substrate stiffness and cytoskeletal contractility regulated whether vinculin and paxillin turnover dynamics are correlated to each other at single FAs. This analysis sheds new insights on the coupling among force, substrate stiffness, and FA dynamics.
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Affiliation(s)
- Dennis W Zhou
- Wallace H. Coulter Department of Biomedical Engineering, Interdisciplinary Bioengineering Graduate Program, Georgia Institute of Technology, Atlanta, GA 30332
| | - Ted T Lee
- Woodruff School of Mechanical Engineering, Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332
| | - Shinuo Weng
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109
| | - Jianping Fu
- Department of Biomedical Engineering and Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109.,Department of Biomedical Engineering and Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Andrés J García
- Woodruff School of Mechanical Engineering, Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332
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17
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Thompson PM, Ramachandran S, Case LB, Tolbert CE, Tandon A, Pershad M, Dokholyan NV, Waterman CM, Campbell SL. A Structural Model for Vinculin Insertion into PIP 2-Containing Membranes and the Effect of Insertion on Vinculin Activation and Localization. Structure 2017; 25:264-275. [PMID: 28089450 DOI: 10.1016/j.str.2016.12.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 11/10/2016] [Accepted: 12/12/2016] [Indexed: 12/20/2022]
Abstract
Vinculin, a scaffolding protein that localizes to focal adhesions (FAs) and adherens junctions, links the actin cytoskeleton to the adhesive super-structure. While vinculin binds to a number of cytoskeletal proteins, it can also associate with phosphatidylinositol 4,5-bisphosphate (PIP2) to drive membrane association. To generate a structural model for PIP2-dependent interaction of vinculin with the lipid bilayer, we conducted lipid-association, nuclear magnetic resonance, and computational modeling experiments. We find that two basic patches on the vinculin tail drive membrane association: the basic collar specifically recognizes PIP2, while the basic ladder drives association with the lipid bilayer. Vinculin mutants with defects in PIP2-dependent liposome association were then expressed in vinculin knockout murine embryonic fibroblasts. Results from these analyses indicate that PIP2 binding is not required for localization of vinculin to FAs or FA strengthening, but is required for vinculin activation and turnover at FAs to promote its association with the force transduction FA nanodomain.
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Affiliation(s)
- Peter M Thompson
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Srinivas Ramachandran
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Lindsay B Case
- Cell Biology and Physiology Center, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Caitlin E Tolbert
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Arpit Tandon
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Mihir Pershad
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Nikolay V Dokholyan
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Clare M Waterman
- Cell Biology and Physiology Center, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sharon L Campbell
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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18
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Differential lipid binding of vinculin isoforms promotes quasi-equivalent dimerization. Proc Natl Acad Sci U S A 2016; 113:9539-44. [PMID: 27503891 DOI: 10.1073/pnas.1600702113] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The main cause of death globally remains debilitating heart conditions, such as dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM), which are often due to mutations of specific components of adhesion complexes. Vinculin regulates these complexes and plays essential roles in intercalated discs that are necessary for muscle cell function and coordinated movement and in the development and function of the heart. Humans bearing familial or sporadic mutations in vinculin suffer from chronic, progressively debilitating DCM that ultimately leads to cardiac failure and death, whereas autosomal dominant mutations in vinculin can also provoke HCM, causing acute cardiac failure. The DCM/HCM-associated mutants of vinculin occur in the 68-residue insert unique to the muscle-specific, alternatively spliced isoform of vinculin, termed metavinculin (MV). Contrary to studies that suggested that phosphoinositol-4,5-bisphosphate (PIP2) only induces vinculin homodimers, which are asymmetric, we show that phospholipid binding results in a domain-swapped symmetric MV dimer via a quasi-equivalent interface compared with vinculin involving R975. Although one of the two PIP2 binding sites is preserved, the symmetric MV dimer that bridges two PIP2 molecules differs from the asymmetric vinculin dimer that bridges only one PIP2 Unlike vinculin, wild-type MV and the DCM/HCM-associated R975W mutant bind PIP2 in their inactive conformations, and R975W MV fails to dimerize. Mutating selective vinculin residues to their corresponding MV residues, or vice versa, switches the isoform's dimeric constellation and lipid binding site. Collectively, our data suggest that MV homodimerization modulates microfilament attachment at muscular adhesion sites and furthers our understanding of MV-mediated cardiac remodeling.
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19
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Yadav R, Vattepu R, Beck MR. Phosphoinositide Binding Inhibits Actin Crosslinking and Polymerization by Palladin. J Mol Biol 2016; 428:4031-4047. [PMID: 27487483 DOI: 10.1016/j.jmb.2016.07.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 07/23/2016] [Accepted: 07/26/2016] [Indexed: 12/11/2022]
Abstract
Actin cytoskeleton remodeling requires the coordinated action of a large number of actin binding proteins that reorganize the actin cytoskeleton by promoting polymerization, stabilizing filaments, causing branching, or crosslinking filaments. Palladin is a key cytoskeletal actin binding protein whose normal function is to enable cell motility during development of tissues and organs of the embryo and in wound healing, but palladin is also responsible for regulating the ability of cancer cells to become invasive and metastatic. The membrane phosphoinositide phosphatidylinositol (PI) 4,5-bisphosphate [PI(4,5)P2] is a well-known precursor for intracellular signaling and a bona fide regulator of actin cytoskeleton reorganization. Our results show that two palladin domains [immunoglobulin (Ig) 3 and 34] interact with the head group of PI(4,5)P2 with moderate affinity (apparent Kd=17μM). Interactions with PI(4,5)P2 decrease the actin polymerizing activity of Ig domain 3 of palladin (Palld-Ig3). Furthermore, NMR titration and docking studies show that residues K38 and K51, which are present on the β-sheet C and D, form salt bridges with the head group of PI(4,5)P2. Moreover, charge neutralization at lysine 38 in the Palld-Ig3 domain severely limits the actin polymerizing and bundling activity of Palld-Ig3. Our results provide biochemical proof that PI(4,5)P2 functions as a moderator of palladin activity and have also identified residues directly involved in the crosslinking activity of palladin.
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Affiliation(s)
- Rahul Yadav
- Chemistry Department, Wichita State University, 1845 Fairmount Street, Wichita, KS 67260, USA.
| | - Ravi Vattepu
- Chemistry Department, Wichita State University, 1845 Fairmount Street, Wichita, KS 67260, USA.
| | - Moriah R Beck
- Chemistry Department, Wichita State University, 1845 Fairmount Street, Wichita, KS 67260, USA.
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20
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Miyano R, Matsumoto T, Takatsu H, Nakayama K, Shin HW. Alteration of transbilayer phospholipid compositions is involved in cell adhesion, cell spreading, and focal adhesion formation. FEBS Lett 2016; 590:2138-45. [PMID: 27277390 DOI: 10.1002/1873-3468.12247] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 05/01/2016] [Accepted: 06/01/2016] [Indexed: 11/11/2022]
Abstract
We previously showed that P4-ATPases, ATP10A/ATP8B1, and ATP11A/ATP11C have flippase activities toward phosphatidylcholine (PC), and aminophospholipids [phosphatidylserine (PS) and phosphatidylethanolamine], respectively. Here, we investigate the effect of PC-specific flippases versus aminophospholipid-specific flippases in cell spreading on the extracellular matrix. Expression of PC-flippases, but not PS-flippases, delayed cell adhesion, cell spreading and inhibited formation of focal adhesions. In addition, overexpression of a PS-binding probe that sequesters PS in the cytoplasmic leaflet delayed cell spreading and inhibited formation of focal adhesions. These results suggest that elevation of PC at the cytoplasmic leaflet of the plasma membrane by expression of PC-flippases may reduce the local concentration of PS or phosphoinositides, required for efficient cell adhesion, focal adhesion formation, and cell spreading.
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Affiliation(s)
- Rie Miyano
- Graduate School of Pharmaceutical Sciences, Kyoto University, Japan
| | | | - Hiroyuki Takatsu
- Graduate School of Pharmaceutical Sciences, Kyoto University, Japan
| | | | - Hye-Won Shin
- Graduate School of Pharmaceutical Sciences, Kyoto University, Japan
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21
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Izard T, Brown DT. Mechanisms and Functions of Vinculin Interactions with Phospholipids at Cell Adhesion Sites. J Biol Chem 2016; 291:2548-55. [PMID: 26728462 DOI: 10.1074/jbc.r115.686493] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The cytoskeletal protein vinculin is a major regulator of cell adhesion and attaches to the cell surface by binding to specific phospholipids. Structural, biochemical, and biological studies provided much insight into how vinculin binds to membranes, what components it recognizes, and how lipid binding is regulated. Here we discuss the roles and mechanisms of phospholipids in regulating the structure and function of vinculin and of its muscle-specific metavinculin splice variant. A full appreciation of these processes is necessary for understanding how vinculin regulates cell motility, migration, and wound healing, and for understanding of its role in cancer and cardiovascular diseases.
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Affiliation(s)
- Tina Izard
- From the Cell Adhesion Laboratory, Department of Cancer Biology and Department of Immunology and Microbial Sciences, The Scripps Research Institute, Jupiter, Florida 33458 and
| | - David T Brown
- the Department of Biochemistry, University of Mississippi Medical Center, Jackson, Mississippi 39216
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22
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Chinthalapudi K, Patil DN, Rangarajan ES, Rader C, Izard T. Lipid-directed vinculin dimerization. Biochemistry 2015; 54:2758-68. [PMID: 25880222 DOI: 10.1021/acs.biochem.5b00015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Vinculin localizes to cellular adhesions where it regulates motility, migration, development, wound healing, and response to force. Importantly, vinculin loss results in cancer phenotypes, cardiovascular disease, and embryonic lethality. At the plasma cell membrane, the most abundant phosphoinositide, phosphatidylinositol 4,5-bisphosphate (PIP2), binds the vinculin tail domain, Vt, and triggers homotypic and heterotypic interactions that amplify binding of vinculin to the actin network. Binding of PIP2 to Vt is necessary for maintaining optimal focal adhesions, for organizing stress fibers, for cell migration and spreading, and for the control of vinculin dynamics and turnover of focal adhesions. While the recently determined Vt/PIP2 crystal structure revealed the conformational changes occurring upon lipid binding and oligomerization, characterization of PIP2-induced vinculin oligomerization has been challenging in the adhesion biology field. Here, via a series of novel biochemical assays not performed in previous studies that relied on chemical cross-linking, we characterize the PIP2-induced vinculin oligomerization. Our results show that Vt/PIP2 forms a tight dimer with Vt or with the muscle-specific vinculin isoform, metavinculin, at sites of adhesion at the cell membrane. Insight into how PIP2 regulates clustering and into mechanisms that regulate cell adhesion allows the development for a more definite sensor for PIP2, and our developed techniques can be applied generally and thus open the door for the characterization of many other protein/PIP2 complexes under physiological conditions.
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Affiliation(s)
- Krishna Chinthalapudi
- †Cell Adhesion Laboratory, ‡Department of Cancer Biology, and §Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Dipak N Patil
- †Cell Adhesion Laboratory, ‡Department of Cancer Biology, and §Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Erumbi S Rangarajan
- †Cell Adhesion Laboratory, ‡Department of Cancer Biology, and §Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Christoph Rader
- †Cell Adhesion Laboratory, ‡Department of Cancer Biology, and §Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Tina Izard
- †Cell Adhesion Laboratory, ‡Department of Cancer Biology, and §Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, Florida 33458, United States
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23
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Vinculin-dependent actin bundling regulates cell migration and traction forces. Biochem J 2015; 465:383-93. [PMID: 25358683 DOI: 10.1042/bj20140872] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Vinculin binding to actin filaments is thought to be critical for force transduction within a cell, but direct experimental evidence to support this conclusion has been limited. In the present study, we found mutation (R1049E) of the vinculin tail impairs its ability to bind F-actin, stimulate actin polymerization, and bundle F-actin in vitro. Further, mutant (R1049E) vinculin expressing cells are altered in cell migration, which is accompanied by changes in cell adhesion, cell spreading and cell generation of traction forces, providing direct evidence for the critical role of vinculin in mechanotransduction at adhesion sites. Lastly, we discuss the viability of models detailing the F-actin-binding surface on vinculin in the context of our mutational analysis.
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24
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Chinthalapudi K, Rangarajan ES, Patil DN, George EM, Brown DT, Izard T. Lipid binding promotes oligomerization and focal adhesion activity of vinculin. ACTA ACUST UNITED AC 2015; 207:643-56. [PMID: 25488920 PMCID: PMC4259812 DOI: 10.1083/jcb.201404128] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
PIP2 binds vinculin and directs its oligomerization, which promotes proper focal adhesion structure and function. Adherens junctions (AJs) and focal adhesion (FA) complexes are necessary for cell migration and morphogenesis, and for the development, growth, and survival of all metazoans. Vinculin is an essential regulator of both AJs and FAs, where it provides links to the actin cytoskeleton. Phosphatidylinositol 4,5-bisphosphate (PIP2) affects the functions of many targets, including vinculin. Here we report the crystal structure of vinculin in complex with PIP2, which revealed that PIP2 binding alters vinculin structure to direct higher-order oligomerization and suggests that PIP2 and F-actin binding to vinculin are mutually permissive. Forced expression of PIP2-binding–deficient mutants of vinculin in vinculin-null mouse embryonic fibroblasts revealed that PIP2 binding is necessary for maintaining optimal FAs, for organization of actin stress fibers, and for cell migration and spreading. Finally, photobleaching experiments indicated that PIP2 binding is required for the control of vinculin dynamics and turnover in FAs. Thus, through oligomerization, PIP2 directs a transient vinculin sequestration at FAs that is necessary for proper FA function.
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Affiliation(s)
- Krishna Chinthalapudi
- Cell Adhesion Laboratory, Department of Cancer Biology, The Scripps Research Institute, Jupiter, FL 33458
| | - Erumbi S Rangarajan
- Cell Adhesion Laboratory, Department of Cancer Biology, The Scripps Research Institute, Jupiter, FL 33458
| | - Dipak N Patil
- Cell Adhesion Laboratory, Department of Cancer Biology, The Scripps Research Institute, Jupiter, FL 33458
| | - Eric M George
- Department of Biochemistry and Department of Physiology, University of Mississippi Medical Center, Jackson, MS 39216 Department of Biochemistry and Department of Physiology, University of Mississippi Medical Center, Jackson, MS 39216
| | - David T Brown
- Department of Biochemistry and Department of Physiology, University of Mississippi Medical Center, Jackson, MS 39216
| | - Tina Izard
- Cell Adhesion Laboratory, Department of Cancer Biology, The Scripps Research Institute, Jupiter, FL 33458
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25
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Tolbert CE, Thompson PM, Superfine R, Burridge K, Campbell SL. Phosphorylation at Y1065 in vinculin mediates actin bundling, cell spreading, and mechanical responses to force. Biochemistry 2014; 53:5526-36. [PMID: 25115937 PMCID: PMC4151700 DOI: 10.1021/bi500678x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
![]()
Vinculin
is an essential structural adaptor protein that localizes
to sites of adhesion and is involved in a number of cell processes
including adhesion, spreading, motility, force transduction, and cell
survival. The C-terminal vinculin tail domain (Vt) contains the necessary
structural components to bind and cross-link actin filaments. Actin
binding to Vt induces a conformational change that promotes dimerization
through the C-terminal hairpin of Vt and enables actin filament cross-linking.
Here we show that Src phosphorylation of Y1065 within the C-terminal
hairpin regulates Vt-mediated actin bundling and provide a detailed
characterization of Y1065 mutations. Furthermore, we show that phosphorylation
at Y1065 plays a role in cell spreading and the response to the application
of mechanical force.
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Affiliation(s)
- Caitlin E Tolbert
- Department of Cell Biology and Physiology, ‡Department of Biochemistry and Biophysics, §Graduate Molecular and Cellular Biophysics Program, ∥Department of Physics and Astronomy, and ⊥the Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States
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26
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Phosphatidylinositol 4,5-bisphosphate triggers activation of focal adhesion kinase by inducing clustering and conformational changes. Proc Natl Acad Sci U S A 2014; 111:E3177-86. [PMID: 25049397 DOI: 10.1073/pnas.1317022111] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Focal adhesion kinase (FAK) is a nonreceptor tyrosine kinase (NRTK) with key roles in integrating growth and cell matrix adhesion signals, and FAK is a major driver of invasion and metastasis in cancer. Cell adhesion via integrin receptors is well known to trigger FAK signaling, and many of the players involved are known; however, mechanistically, FAK activation is not understood. Here, using a multidisciplinary approach, including biochemical, biophysical, structural, computational, and cell biology approaches, we provide a detailed view of a multistep activation mechanism of FAK initiated by phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2]. Interestingly, the mechanism differs from canonical NRTK activation and is tailored to the dual catalytic and scaffolding function of FAK. We find PI(4,5)P2 induces clustering of FAK on the lipid bilayer by binding a basic region in the regulatory 4.1, ezrin, radixin, moesin homology (FERM) domain. In these clusters, PI(4,5)P2 induces a partially open FAK conformation where the autophosphorylation site is exposed, facilitating efficient autophosphorylation and subsequent Src recruitment. However, PI(4,5)P2 does not release autoinhibitory interactions; rather, Src phosphorylation of the activation loop in FAK results in release of the FERM/kinase tether and full catalytic activation. We propose that PI(4,5)P2 and its generation in focal adhesions by the enzyme phosphatidylinositol 4-phosphate 5-kinase type Iγ are important in linking integrin signaling to FAK activation.
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27
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Thompson PM, Tolbert CE, Shen K, Kota P, Palmer SM, Plevock KM, Orlova A, Galkin VE, Burridge K, Egelman EH, Dokholyan NV, Superfine R, Campbell SL. Identification of an actin binding surface on vinculin that mediates mechanical cell and focal adhesion properties. Structure 2014; 22:697-706. [PMID: 24685146 DOI: 10.1016/j.str.2014.03.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 02/04/2014] [Accepted: 03/04/2014] [Indexed: 11/30/2022]
Abstract
Vinculin, a cytoskeletal scaffold protein essential for embryogenesis and cardiovascular function, localizes to focal adhesions and adherens junctions, connecting cell surface receptors to the actin cytoskeleton. While vinculin interacts with many adhesion proteins, its interaction with filamentous actin regulates cell morphology, motility, and mechanotransduction. Disruption of this interaction lowers cell traction forces and enhances actin flow rates. Although a model for the vinculin:actin complex exists, we recently identified actin-binding deficient mutants of vinculin outside sites predicted to bind actin and developed an alternative model to better define this actin-binding surface, using negative-stain electron microscopy (EM), discrete molecular dynamics, and mutagenesis. Actin-binding deficient vinculin variants expressed in vinculin knockout fibroblasts fail to rescue cell-spreading defects and reduce cellular response to external force. These findings highlight the importance of this actin-binding surface and provide the molecular basis for elucidating additional roles of this interaction, including actin-induced conformational changes that promote actin bundling.
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Affiliation(s)
- Peter M Thompson
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Molecular and Cellular Biophysics Program, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Caitlin E Tolbert
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Kai Shen
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Pradeep Kota
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Molecular and Cellular Biophysics Program, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Sean M Palmer
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Molecular and Cellular Biophysics Program, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Karen M Plevock
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Molecular and Cellular Biophysics Program, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Albina Orlova
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA
| | - Vitold E Galkin
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA
| | - Keith Burridge
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Edward H Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA
| | - Nikolay V Dokholyan
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Richard Superfine
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Sharon L Campbell
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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28
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García-González V, Gutiérrez-Quintanar N, Mendoza-Espinosa P, Brocos P, Piñeiro A, Mas-Oliva J. Key structural arrangements at the C-terminus domain of CETP suggest a potential mechanism for lipid-transfer activity. J Struct Biol 2014; 186:19-27. [PMID: 24530617 DOI: 10.1016/j.jsb.2014.02.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 02/04/2014] [Accepted: 02/10/2014] [Indexed: 01/25/2023]
Abstract
The cholesteryl-ester transfer protein (CETP) promotes cholesteryl-ester and triglyceride transfer between lipoproteins. We evaluated the secondary structure stability of a series of small peptides derived from the C-terminus of CETP in a wide range of pH's and lipid mixtures, and studied their capability to carry out disorder-to-order secondary structure transitions dependent of lipids. We report that while a mixture of phosphatidylcholine/cholesteryl-esters forms large aggregated particles, the inclusion of a series of CETP carboxy-terminal peptides in a stable α-helix conformation, allows the formation of small homogeneous micelle-like structures. This phenomenon of lipid ordering was directly connected to secondary structural transitions at the C-terminus domain when lysophosphatidic acid and lysophosphatidylcholine lipids were employed. Circular dichroism, cosedimentation experiments, electron microscopy, as well as molecular dynamics simulations confirm this phenomenon. When purified CETP is studied, the same type of phenomenon occurs by promoting the reorganization of lipid from large to smaller particles. Our findings extend the emerging view for a novel mechanism of lipid transfer carried out by CETP, assigning its C-terminus domain the property to accomplish lipid ordering through secondary structure disorder-to-order transitions.
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Affiliation(s)
- Victor García-González
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510 México, D.F., Mexico
| | - Nadia Gutiérrez-Quintanar
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510 México, D.F., Mexico
| | - Paola Mendoza-Espinosa
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510 México, D.F., Mexico
| | - Pilar Brocos
- Departamento de Física Aplicada, Facultad de Física, Universidad de Santiago de Compostela, Spain
| | - Angel Piñeiro
- Departamento de Física Aplicada, Facultad de Física, Universidad de Santiago de Compostela, Spain
| | - Jaime Mas-Oliva
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510 México, D.F., Mexico; División de Investigación, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico.
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Zemljic-Harpf AE, Godoy JC, Platoshyn O, Asfaw EK, Busija AR, Domenighetti AA, Ross RS. Vinculin directly binds zonula occludens-1 and is essential for stabilizing connexin-43-containing gap junctions in cardiac myocytes. J Cell Sci 2014; 127:1104-16. [PMID: 24413171 DOI: 10.1242/jcs.143743] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Vinculin (Vcl) links actin filaments to integrin- and cadherin-based cellular junctions. Zonula occludens-1 (ZO-1, also known as TJP1) binds connexin-43 (Cx43, also known as GJA1), cadherin and actin. Vcl and ZO-1 anchor the actin cytoskeleton to the sarcolemma. Given that loss of Vcl from cardiomyocytes causes maldistribution of Cx43 and predisposes cardiomyocyte-specific Vcl-knockout mice with preserved heart function to arrhythmia and sudden death, we hypothesized that Vcl and ZO-1 interact and that loss of this interaction destabilizes gap junctions. We found that Vcl, Cx43 and ZO-1 colocalized at the intercalated disc. Loss of cardiomyocyte Vcl caused parallel loss of ZO-1 from intercalated dics. Vcl co-immunoprecipitated Cx43 and ZO-1, and directly bound ZO-1 in yeast two-hybrid studies. Excision of the Vcl gene in neonatal mouse cardiomyocytes caused a reduction in the amount of Vcl mRNA transcript and protein expression leading to (1) decreased protein expression of Cx43, ZO-1, talin, and β1D-integrin, (2) reduced PI3K activation, (3) increased activation of Akt, Erk1 and Erk2, and (4) cardiomyocyte necrosis. In summary, this is the first study showing a direct interaction between Vcl and ZO-1 and illustrates how Vcl plays a crucial role in stabilizing gap junctions and myocyte integrity.
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Huang Y, Day RN, Gunst SJ. Vinculin phosphorylation at Tyr1065 regulates vinculin conformation and tension development in airway smooth muscle tissues. J Biol Chem 2013; 289:3677-88. [PMID: 24338477 DOI: 10.1074/jbc.m113.508077] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Vinculin localizes to membrane adhesion junctions in smooth muscle tissues, where its head domain binds to talin and its tail domain binds to filamentous actin, thus linking actin filaments to the extracellular matrix. Vinculin can assume a closed conformation, in which the head and tail domains bind to each other and mask the binding sites for actin and talin, and an open activated conformation that exposes the binding sites for talin and actin. Acetylcholine stimulation of tracheal smooth muscle tissues induces the recruitment of vinculin to the cell membrane and its interaction with talin and actin, which is required for active tension development. Vinculin phosphorylation at Tyr(1065) on its C terminus increases concurrently with tension development in tracheal smooth muscle tissues. In the present study, the role of vinculin phosphorylation at Tyr(1065) in regulating the conformation and function of vinculin during airway smooth muscle contraction was evaluated. Vinculin constructs with point mutations at Tyr(1065) (vinculin Y1065F and vinculin Y1065E) and vinculin conformation-sensitive FRET probes were expressed in smooth muscle tissues to determine how Tyr(1065) phosphorylation affects smooth muscle contraction and the conformation and cellular functions of vinculin. The results show that vinculin phosphorylation at tyrosine 1065 is required for normal tension generation in airway smooth muscle during contractile stimulation and that Tyr(1065) phosphorylation regulates the conformation and scaffolding activity of the vinculin molecule. We conclude that the phosphorylation of vinculin at tyrosine 1065 provides a mechanism for regulating the function of vinculin in airway smooth muscle in response to contractile stimulation.
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Affiliation(s)
- Youliang Huang
- From the Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana 46202-5120
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31
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Abstract
Vinculin can interact with F-actin both in recruitment of actin filaments to the growing focal adhesions and also in capping of actin filaments to regulate actin dynamics. Using molecular dynamics, both interactions are simulated using different vinculin conformations. Vinculin is simulated either with only its vinculin tail domain (Vt), with all residues in its closed conformation, with all residues in an open I conformation, and with all residues in an open II conformation. The open I conformation results from movement of domain 1 away from Vt; the open II conformation results from complete dissociation of Vt from the vinculin head domains. Simulation of vinculin binding along the actin filament showed that Vt alone can bind along the actin filaments, that vinculin in its closed conformation cannot bind along the actin filaments, and that vinculin in its open I conformation can bind along the actin filaments. The simulations confirm that movement of domain 1 away from Vt in formation of vinculin 1 is sufficient for allowing Vt to bind along the actin filament. Simulation of Vt capping actin filaments probe six possible bound structures and suggest that vinculin would cap actin filaments by interacting with both S1 and S3 of the barbed-end, using the surface of Vt normally occluded by D4 and nearby vinculin head domain residues. Simulation of D4 separation from Vt after D1 separation formed the open II conformation. Binding of open II vinculin to the barbed-end suggests this conformation allows for vinculin capping. Three binding sites on F-actin are suggested as regions that could link to vinculin. Vinculin is suggested to function as a variable switch at the focal adhesions. The conformation of vinculin and the precise F-actin binding conformation is dependent on the level of mechanical load on the focal adhesion. The interface between a cell and its substrate is strengthened by the formation of focal adhesions. In this study molecular dynamics simulations are used to explore the connectivity of one focal adhesion forming protein, vinculin, and the cytoskeletal filament, F-actin. The simulations demonstrate: (1) that vinculin can link along F-actin at these focal adhesions when it adopts an open conformation, (2) that the vinculin tail (Vt) can bind F-actin at its barbed-end preventing actin polymerization, (3) that vinculin can adopt two open conformations, and (4) that the second open conformation is necessary for vinculin to cap the actin filament. The results suggest that vinculin can act as a variable switch, changing its shape and the nature of its interaction with F-actin depending on the level of stress seen at a focal adhesion. Under the highest stress vinculin would adopt the open II conformation and link anywhere on F-actin, even its barbed-end. Under less stress vinculin could adopt the open I conformation and bind along F-actin. And under minimal stress vinculin could adopt its closed conformation. This variability allows for vinculin to truly function as the cell's mechanical reinforcing agent.
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Tangney J, Chuang J, Janssen M, Krishnamurthy A, Liao P, Hoshijima M, Wu X, Meininger G, Muthuchamy M, Zemljic-Harpf A, Ross R, Frank L, McCulloch A, Omens J. Novel role for vinculin in ventricular myocyte mechanics and dysfunction. Biophys J 2013; 104:1623-33. [PMID: 23561539 PMCID: PMC3617425 DOI: 10.1016/j.bpj.2013.02.021] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Revised: 01/07/2013] [Accepted: 02/07/2013] [Indexed: 01/23/2023] Open
Abstract
Vinculin (Vcl) plays a key structural role in ventricular myocytes that, when disrupted, can lead to contractile dysfunction and dilated cardiomyopathy. To investigate the role of Vcl in myocyte and myocardial function, cardiomyocyte-specific Vcl knockout mice (cVclKO) and littermate control wild-type mice were studied with transmission electron microscopy (TEM) and in vivo magnetic resonance imaging (MRI) tagging before the onset of global ventricular dysfunction. MRI revealed significantly decreased systolic strains transverse to the myofiber axis in vivo, but no changes along the muscle fibers or in fiber tension in papillary muscles from heterozygous global Vcl null mice. Myofilament lattice spacing from TEM was significantly greater in cVclKO versus wild-type hearts fixed in the unloaded state. AFM in Vcl heterozygous null mouse myocytes showed a significant decrease in membrane cortical stiffness. A multiscale computational model of ventricular mechanics incorporating cross-bridge geometry and lattice mechanics showed that increased transverse systolic stiffness due to increased lattice spacing may explain the systolic wall strains associated with Vcl deficiency, before the onset of ventricular dysfunction. Loss of cardiac myocyte Vcl may decrease systolic transverse strains in vivo by decreasing membrane cortical tension, which decreases transverse compression of the lattice thereby increasing interfilament spacing and stress transverse to the myofibers.
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Affiliation(s)
- Jared R. Tangney
- Department of Bioengineering, University of California-San Diego, La Jolla, California
| | - Joyce S. Chuang
- Department of Bioengineering, University of California-San Diego, La Jolla, California
| | - Matthew S. Janssen
- Department of Bioengineering, University of California-San Diego, La Jolla, California
| | - Adarsh Krishnamurthy
- Department of Bioengineering, University of California-San Diego, La Jolla, California
| | - Peter Liao
- Department of Medicine, University of California-San Diego, La Jolla, California
- Veterans Administration Healthcare San Diego, San Diego, California
| | - Masahiko Hoshijima
- Department of Medicine, University of California-San Diego, La Jolla, California
- Cardiac Biomedical Science and Engineering Center, University of California-San Diego, La Jolla, California
| | - Xin Wu
- Department of Systems Biology and Translational Medicine, Texas A&M Health Science Center, College of Medicine, College Station, Texas
| | - Gerald A. Meininger
- Dalton Cardiovascular Research Center and Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Mariappan Muthuchamy
- Department of Systems Biology and Translational Medicine, Texas A&M Health Science Center, College of Medicine, College Station, Texas
| | - Alice Zemljic-Harpf
- Department of Medicine, University of California-San Diego, La Jolla, California
- Veterans Administration Healthcare San Diego, San Diego, California
| | - Robert S. Ross
- Department of Medicine, University of California-San Diego, La Jolla, California
- Veterans Administration Healthcare San Diego, San Diego, California
- Cardiac Biomedical Science and Engineering Center, University of California-San Diego, La Jolla, California
| | - Lawrence R. Frank
- Department of Radiology, University of California-San Diego, La Jolla, California
| | - Andrew D. McCulloch
- Department of Bioengineering, University of California-San Diego, La Jolla, California
- Department of Medicine, University of California-San Diego, La Jolla, California
- Cardiac Biomedical Science and Engineering Center, University of California-San Diego, La Jolla, California
| | - Jeffrey H. Omens
- Department of Bioengineering, University of California-San Diego, La Jolla, California
- Department of Medicine, University of California-San Diego, La Jolla, California
- Cardiac Biomedical Science and Engineering Center, University of California-San Diego, La Jolla, California
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Vinculin and metavinculin: Oligomerization and interactions with F-actin. FEBS Lett 2013; 587:1220-9. [DOI: 10.1016/j.febslet.2013.02.042] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 02/20/2013] [Accepted: 02/20/2013] [Indexed: 01/09/2023]
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Prasad Gajula MNV, Vogel KP, Rai A, Dietrich F, Steinhoff HJ. How far in-silico computing meets real experiments. A study on the structure and dynamics of spin labeled vinculin tail protein by molecular dynamics simulations and EPR spectroscopy. BMC Genomics 2013; 14 Suppl 2:S4. [PMID: 23445506 PMCID: PMC3582443 DOI: 10.1186/1471-2164-14-s2-s4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Background Investigation of conformational changes in a protein is a prerequisite to understand its biological function. To explore these conformational changes in proteins we developed a strategy with the combination of molecular dynamics (MD) simulations and electron paramagnetic resonance (EPR) spectroscopy. The major goal of this work is to investigate how far computer simulations can meet the experiments. Methods Vinculin tail protein is chosen as a model system as conformational changes within the vinculin protein are believed to be important for its biological function at the sites of cell adhesion. MD simulations were performed on vinculin tail protein both in water and in vacuo environments. EPR experimental data is compared with those of the simulated data for corresponding spin label positions. Results The calculated EPR spectra from MD simulations trajectories of selected spin labelled positions are comparable to experimental EPR spectra. The results show that the information contained in the spin label mobility provides a powerful means of mapping protein folds and their conformational changes. Conclusions The results suggest the localization of dynamic and flexible regions of the vinculin tail protein. This study shows MD simulations can be used as a complementary tool to interpret experimental EPR data.
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Affiliation(s)
- M N V Prasad Gajula
- CABin division, DST Ramanujan Fellow, Indian Agricultural Statistics Research Institute, PUSA campus, New Delhi-110012, India.
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Tolbert CE, Burridge K, Campbell SL. Vinculin regulation of F-actin bundle formation: what does it mean for the cell? Cell Adh Migr 2013; 7:219-25. [PMID: 23307141 DOI: 10.4161/cam.23184] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Vinculin is an essential cell adhesion protein, found at both focal adhesions and adherens junctions, where it couples transmembrane proteins to the actin cytoskeleton. Vinculin is involved in controlling cell shape, motility and cell survival, and has more recently been shown to play a role in force transduction. The tail domain of vinculin (Vt) has the ability to both bind and bundle actin filaments. Binding to actin induces a conformational change in Vt believed to promote formation of a Vt dimer that is able to crosslink actin filaments. We have recently provided additional evidence for the actin-induced Vt dimer and have shown that the vinculin carboxyl (C)-terminal hairpin is critical for both the formation of the Vt dimer and for bundling F-actin. We have also demonstrated the importance of the C-terminal hairpin in cells as deletion of this region impacts both adhesion properties and force transduction. Intriguingly, we have identified bundling deficient variants of vinculin that show different cellular phenotypes. These results suggest additional role(s) for the C-terminal hairpin, distinct from its bundling function. In this commentary, we will expand on our previous findings and further investigate these actin bundling deficient vinculin variants.
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Affiliation(s)
- Caitlin E Tolbert
- Department of Cell Biology and Physiology, University of North Carolina School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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36
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Golji J, Wendorff T, Mofrad MRK. Phosphorylation primes vinculin for activation. Biophys J 2012; 102:2022-30. [PMID: 22824265 DOI: 10.1016/j.bpj.2012.01.062] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2011] [Revised: 12/29/2011] [Accepted: 01/31/2012] [Indexed: 01/13/2023] Open
Abstract
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.
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Affiliation(s)
- Javad Golji
- Molecular Cell Biomechanics Laboratory, Department of Bioengineering, University of California, Berkeley, CA, USA
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37
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Stimulus-dependent phosphorylation of profilin-1 in angiogenesis. Nat Cell Biol 2012; 14:1046-56. [PMID: 23000962 DOI: 10.1038/ncb2580] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Accepted: 08/13/2012] [Indexed: 12/12/2022]
Abstract
Angiogenesis, the formation of new blood vessels, is fundamental to development and post-injury tissue repair. Vascular endothelial growth factor (VEGF)-A guides and enhances endothelial cell migration to initiate angiogenesis. Profilin-1 (Pfn-1) is an actin-binding protein that enhances actin filament formation and cell migration, but stimulus-dependent regulation of Pfn-1 has not been observed. Here, we show that VEGF-A-inducible phosphorylation of Pfn-1 at Tyr 129 is critical for endothelial cell migration and angiogenesis. Chemotactic activation of VEGF receptor kinase-2 (VEGFR2) and Src induces Pfn-1 phosphorylation in the cell leading edge, promoting Pfn-1 binding to actin and actin polymerization. Conditional endothelial knock-in of phosphorylation-deficient Pfn1(Y129F) in mice reveals that Pfn-1 phosphorylation is critical for angiogenesis in response to wounding and ischaemic injury, but not for developmental angiogenesis. Thus, VEGFR2/Src-mediated phosphorylation of Pfn-1 bypasses canonical, multistep intracellular signalling events to initiate endothelial cell migration and angiogenesis, and might serve as a selective therapeutic target for anti-angiogenic therapy.
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38
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Lee JH, Rangarajan ES, Vonrhein C, Bricogne G, Izard T. The metavinculin tail domain directs constitutive interactions with raver1 and vinculin RNA. J Mol Biol 2012; 422:697-704. [PMID: 22709580 DOI: 10.1016/j.jmb.2012.06.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Revised: 05/02/2012] [Accepted: 06/11/2012] [Indexed: 11/26/2022]
Abstract
Vinculin is a key regulator of the actin cytoskeleton attachment to the cell membrane at cellular adhesion sites, which is crucial for processes such as cell motility and migration, development, survival, and wound healing. Vinculin loss results in embryonic lethality, cardiovascular diseases, and cancer. Its tail domain, Vt, is crucial for vinculin activation and focal adhesion turnover and binds to the actin cytoskeleton and acidic phospholipids upon which it unfurls. The RNA binding protein raver1 regulates the assembly of focal adhesions transcriptionally by binding to vinculin. The muscle-specific splice form, metavinculin, is characterized by a 68-residue insert in the tail domain (MVt) and correlates with hereditary idiopathic dilated cardiomyopathy. Here, we report that metavinculin can bind to raver1 in its inactive state. Our crystal structure explains this permissivity, where an extended coil unique to MVt is unfurled in the MVtΔ954:raver1 complex structure. Our binding assays show that raver1 forms a ternary complex with MVt and vinculin mRNA. These findings suggest that the metavinculin:raver1:RNA complex is constitutively recruited to adhesion complexes.
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Affiliation(s)
- Jun Hyuck Lee
- Department of Cancer Biology, Cell Adhesion Laboratory, The Scripps Research Institute, FL 33458, USA
| | - Erumbi S Rangarajan
- Department of Cancer Biology, Cell Adhesion Laboratory, The Scripps Research Institute, FL 33458, USA
| | - Clemens Vonrhein
- Global Phasing Ltd., Sheraton House, Castle Park, Cambridge CB3 0AX, UK
| | - Gerard Bricogne
- Global Phasing Ltd., Sheraton House, Castle Park, Cambridge CB3 0AX, UK
| | - Tina Izard
- Department of Cancer Biology, Cell Adhesion Laboratory, The Scripps Research Institute, FL 33458, USA.
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Legate KR, Takahashi S, Bonakdar N, Fabry B, Boettiger D, Zent R, Fässler R. Integrin adhesion and force coupling are independently regulated by localized PtdIns(4,5)2 synthesis. EMBO J 2012; 30:4539-53. [PMID: 21926969 DOI: 10.1038/emboj.2011.332] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2011] [Accepted: 08/19/2011] [Indexed: 01/23/2023] Open
Abstract
The 90-kDa isoform of the lipid kinase PIP kinase Type I γ (PIPKIγ) localizes to focal adhesions (FAs), where it provides a local source of phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P(2)). Although PtdIns(4,5)P(2) regulates the function of several FA-associated molecules, the role of the FA-specific pool of PtdIns(4,5)P(2) is not known. We report that the genetic ablation of PIPKIγ specifically from FAs results in defective integrin-mediated adhesion and force coupling. Adhesion defects in cells deficient in FAPtdIns(4,5)P(2) synthesis are corrected within minutes while integrin-actin force coupling remains defective over a longer period. Talin and vinculin, but not kindlin, are less efficiently recruited to new adhesions in these cells. These data demonstrate that the specific depletion of PtdIns(4,5)P(2) from FAs temporally separates integrin-ligand binding from integrin-actin force coupling by regulating talin and vinculin recruitment. Furthermore, it suggests that force coupling relies heavily on locally generated PtdIns(4,5)P(2) rather than bulk membrane PtdIns(4,5)P(2).
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Affiliation(s)
- Kyle R Legate
- Department of Molecular Medicine, Max Planck Institute of Biochemistry, Martinsried, Germany
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40
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Abé C, Dietrich F, Gajula P, Benz M, Vogel KP, van Gastel M, Illenberger S, Ziegler WH, Steinhoff HJ. Monomeric and dimeric conformation of the vinculin tail five-helix bundle in solution studied by EPR spectroscopy. Biophys J 2012; 101:1772-80. [PMID: 21961604 DOI: 10.1016/j.bpj.2011.08.048] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 08/03/2011] [Accepted: 08/31/2011] [Indexed: 11/28/2022] Open
Abstract
The cytoskeletal adaptor protein vinculin plays an important role in the control of cell adhesion and migration, linking the actin cytoskeleton to adhesion receptor complexes in cell adhesion sites. The conformation of the vinculin tail dimer, which is crucial for protein function, was analyzed using site-directed spin labeling in electron paramagnetic resonance spectroscopy. Interspin distances for a set of six singly and four doubly spin-labeled mutants of the tail domain of vinculin were determined and used as constraints for modeling of the vinculin tail dimer. A comparison of the results obtained by molecular dynamic simulations and a rotamer library approach reveals that the crystal structure of the vinculin tail monomer is essentially preserved in aqueous solution. The orientation of monomers within the dimer observed previously by x-ray crystallography agrees with the solution electron paramagnetic resonance data. Furthermore, the distance between positions 1033 is shown to increase by >3 nm upon interaction of the vinculin tail domain with F-actin.
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Affiliation(s)
- Christoph Abé
- Department of Physics, University of Osnabrück, Osnabrück, Germany
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41
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Wehrle-Haller B. Structure and function of focal adhesions. Curr Opin Cell Biol 2011; 24:116-24. [PMID: 22138388 DOI: 10.1016/j.ceb.2011.11.001] [Citation(s) in RCA: 163] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Revised: 11/01/2011] [Accepted: 11/02/2011] [Indexed: 01/17/2023]
Abstract
Integrin-dependent cell adhesions come in different shapes and serve in different cell types for tasks ranging from cell-adhesion, migration, and the remodeling of the extracellular matrix to the formation and stabilization of immunological and chemical synapses. A major challenge consists in the identification of adhesion-specific as well as common regulatory mechanisms, motivating the need for a deeper analysis of protein-protein interactions in the context of intact focal adhesions. Specifically, it is critical to understand how small differences in binding of integrins to extracellular ligands and/or cytoplasmic adapter proteins affect the assembly and function of an entire focal adhesion. By using the talin-integrin pair as a starting point, I would like to discuss how specific protein-protein and protein-lipid interactions can control the behavior and function of focal adhesions. By responding to chemical and mechanical cues several allosterically regulated proteins create a dynamic multifunctional protein network that provides both adhesion to the extracellular matrix as well as intracellular signaling in response to mechanical changes in the cellular environment.
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Affiliation(s)
- Bernhard Wehrle-Haller
- University of Geneva, Department of Cell Physiology and Metabolism, Centre Médical Universitaire, 1. Rue Michel-Servet, 1211 Geneva 4, Switzerland.
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Shen K, Tolbert CE, Guilluy C, Swaminathan VS, Berginski ME, Burridge K, Superfine R, Campbell SL. The vinculin C-terminal hairpin mediates F-actin bundle formation, focal adhesion, and cell mechanical properties. J Biol Chem 2011; 286:45103-15. [PMID: 22052910 DOI: 10.1074/jbc.m111.244293] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Vinculin is an essential and highly conserved cell adhesion protein, found at both focal adhesions and adherens junctions, where it couples integrins or cadherins to the actin cytoskeleton. Vinculin is involved in controlling cell shape, motility, and cell survival, and has more recently been shown to play a role in force transduction. The tail domain of vinculin (Vt) contains determinants necessary for binding and bundling of actin filaments. Actin binding to Vt has been proposed to induce formation of a Vt dimer that is necessary for cross-linking actin filaments. Results from this study provide additional support for actin-induced Vt self-association. Moreover, the actin-induced Vt dimer appears distinct from the dimer formed in the absence of actin. To better characterize the role of the Vt strap and carboxyl terminus (CT) in actin binding, Vt self-association, and actin bundling, we employed smaller amino-terminal (NT) and CT deletions that do not perturb the structural integrity of Vt. Although both NT and CT deletions retain actin binding, removal of the CT hairpin (1061-1066) selectively impairs actin bundling in vitro. Moreover, expression of vinculin lacking the CT hairpin in vinculin knock-out murine embryonic fibroblasts affects the number of focal adhesions formed, cell spreading as well as cellular stiffening in response to mechanical force.
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Affiliation(s)
- Kai Shen
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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Abstract
Inositol phospholipids have been implicated in almost all aspects of cellular physiology including spatiotemporal regulation of cellular signaling, acquisition of cellular polarity, specification of membrane identity, cytoskeletal dynamics, and regulation of cellular adhesion, motility, and cytokinesis. In this review, we examine the critical role phosphoinositides play in these processes to execute the establishment and maintenance of cellular architecture. Epithelial tissues perform essential barrier and transport functions in almost all major organs. Key to their development and function is the establishment of epithelial cell polarity. We place a special emphasis on highlighting recent studies demonstrating phosphoinositide regulation of epithelial cell polarity and how individual cells use phosphoinositides to further organize into epithelial tissues.
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Affiliation(s)
- Annette Shewan
- Department of Anatomy, University of California, San Francisco, San Francisco, California 94143-2140, USA
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44
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Sahab ZJ, Man YG, Byers SW, Sang QXA. Putative biomarkers and targets of estrogen receptor negative human breast cancer. Int J Mol Sci 2011; 12:4504-21. [PMID: 21845093 PMCID: PMC3155366 DOI: 10.3390/ijms12074504] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Revised: 06/27/2011] [Accepted: 07/04/2011] [Indexed: 11/26/2022] Open
Abstract
Breast cancer is a progressive and potentially fatal disease that affects women of all ages. Like all progressive diseases, early and reliable diagnosis is the key for successful treatment and annihilation. Biomarkers serve as indicators of pathological, physiological, or pharmacological processes. Her2/neu, CA15.3, estrogen receptor (ER), progesterone receptor (PR), and cytokeratins are biomarkers that have been approved by the Food and Drug Administration for disease diagnosis, prognosis, and therapy selection. The structural and functional complexity of protein biomarkers and the heterogeneity of the breast cancer pathology present challenges to the scientific community. Here we review estrogen receptor-related putative breast cancer biomarkers, including those of putative breast cancer stem cells, a minor population of estrogen receptor negative tumor cells that retain the stem cell property of self-renewal. We also review a few promising cytoskeleton targets for ER alpha negative breast cancer.
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Affiliation(s)
- Ziad J. Sahab
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20007, USA; E-Mail:
| | - Yan-Gao Man
- Diagnostic and Translational Research Center, Henry Jackson Foundation for the Advancement of Military Medicine, Gaithersburg, MD 20789, USA; E-Mail:
- Jilin University, Changchun 130012, China
| | - Stephen W. Byers
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20007, USA; E-Mail:
| | - Qing-Xiang A. Sang
- Department of Chemistry and Biochemistry and Institute of Molecular Biophysics, Florida State University, 102 Varsity Way, Tallahassee, FL 32306, USA; E-Mail:
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Kim DH, Choi JW, Joo JI, Wang X, Choi DK, Oh TS, Yun JW. Changes in expression of skeletal muscle proteins between obesity-prone and obesity-resistant rats induced by a high-fat diet. J Proteome Res 2011; 10:1281-92. [PMID: 21142077 DOI: 10.1021/pr101048q] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A primary goal in obesity research is to determine why some people become obese (obesity-prone, OP) and others do not (obesity-resistant, OR) when exposed to high-calorie diets. The metabolic changes that cause reduced adiposity and resistance to obesity development have yet to be determined. We thus performed proteomic analysis on muscular proteins from OP and OR rats in order to determine whether other novel molecules are involved in this response. To this end, rats were fed a low- or high-fat diet for 8 weeks and were then classified into OP and OR rats by body weight gain. OP rats gained about 25% more body weight than OR rats, even though food intake did not differ significantly between the two groups. Proteomic analysis using 2-DE demonstrated differential expression of 26 spots from a total of 658 matched spots, of which 23 spots were identified as skeletal muscle proteins altered between OP and OR rats by peptide mass fingerprinting. Muscle proteome data enabled us to draw the conclusion that enhanced regulation of proteins involved in lipid metabolism and muscle contraction, as well as increased expression of marker proteins for oxidative muscle type (type I), contributed to obesity-resistance; however, antioxidative proteins did not.
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Affiliation(s)
- Dong Hyun Kim
- Department of Biotechnology, Daegu University, Kynungsan, Kyungbuk, Republic of Korea
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Wirth VF, List F, Diez G, Goldmann WH. Vinculin's C-terminal region facilitates phospholipid membrane insertion. Biochem Biophys Res Commun 2010; 398:433-7. [PMID: 20599708 DOI: 10.1016/j.bbrc.2010.06.094] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2010] [Accepted: 06/23/2010] [Indexed: 01/13/2023]
Abstract
The focal adhesion protein vinculin has been implicated in associating with soluble and membranous phospholipids. Here, we investigated the intermolecular interactions of two vinculin tail domains with membrane phospholipids. Previous studies have shown that the tail's unstructured C-terminus affects the mechanical behavior of cells, but not the H3 region. The aim of this work was to establish whether the C-terminal or the H3 region either associate favorably with or anchor in lipid membranes. This work characterizes the energetics and dynamics of phospholipid interactions using differential scanning calorimetry (DSC) as well as circular dichroism (CD) spectroscopy. Biochemical data from tryptophan quenching and SDS-PAGE experiments support calorimetric and CD spectroscopic findings insofar that only vinculin's C-terminus inserts into lipid membranes. These in vitro results provide further insight into the mechanical behavior of vinculin tail regions in cells and contribute to the understanding of their structure and function.
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Affiliation(s)
- Volker F Wirth
- Center for Medical Physics and Technology, Biophysics Group, Friedrich-Alexander-University, Erlangen-Nuremberg, Erlangen, Germany
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A helix replacement mechanism directs metavinculin functions. PLoS One 2010; 5:e10679. [PMID: 20502710 PMCID: PMC2873289 DOI: 10.1371/journal.pone.0010679] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Accepted: 04/15/2010] [Indexed: 11/25/2022] Open
Abstract
Cells require distinct adhesion complexes to form contacts with their neighbors or the extracellular matrix, and vinculin links these complexes to the actin cytoskeleton. Metavinculin, an isoform of vinculin that harbors a unique 68-residue insert in its tail domain, has distinct actin bundling and oligomerization properties and plays essential roles in muscle development and homeostasis. Moreover, patients with sporadic or familial mutations in the metavinculin-specific insert invariably develop fatal cardiomyopathies. Here we report the high resolution crystal structure of the metavinculin tail domain, as well as the crystal structures of full-length human native metavinculin (1,134 residues) and of the full-length cardiomyopathy-associated ΔLeu954 metavinculin deletion mutant. These structures reveal that an α-helix (H1′) and extended coil of the metavinculin insert replace α-helix H1 and its preceding extended coil found in the N-terminal region of the vinculin tail domain to form a new five-helix bundle tail domain. Further, biochemical analyses demonstrate that this helix replacement directs the distinct actin bundling and oligomerization properties of metavinculin. Finally, the cardiomyopathy associated ΔLeu954 and Arg975Trp metavinculin mutants reside on the replaced extended coil and the H1′ α-helix, respectively. Thus, a helix replacement mechanism directs metavinculin's unique functions.
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Saarikangas J, Zhao H, Lappalainen P. Regulation of the actin cytoskeleton-plasma membrane interplay by phosphoinositides. Physiol Rev 2010; 90:259-89. [PMID: 20086078 DOI: 10.1152/physrev.00036.2009] [Citation(s) in RCA: 362] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The plasma membrane and the underlying cortical actin cytoskeleton undergo continuous dynamic interplay that is responsible for many essential aspects of cell physiology. Polymerization of actin filaments against cellular membranes provides the force for a number of cellular processes such as migration, morphogenesis, and endocytosis. Plasma membrane phosphoinositides (especially phosphatidylinositol bis- and trisphosphates) play a central role in regulating the organization and dynamics of the actin cytoskeleton by acting as platforms for protein recruitment, by triggering signaling cascades, and by directly regulating the activities of actin-binding proteins. Furthermore, a number of actin-associated proteins, such as BAR domain proteins, are capable of directly deforming phosphoinositide-rich membranes to induce plasma membrane protrusions or invaginations. Recent studies have also provided evidence that the actin cytoskeleton-plasma membrane interactions are misregulated in a number of pathological conditions such as cancer and during pathogen invasion. Here, we summarize the wealth of knowledge on how the cortical actin cytoskeleton is regulated by phosphoinositides during various cell biological processes. We also discuss the mechanisms by which interplay between actin dynamics and certain membrane deforming proteins regulate the morphology of the plasma membrane.
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Affiliation(s)
- Juha Saarikangas
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
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