1
|
Rangarajan ES, Smith EW, Izard T. Distinct inter-domain interactions of dimeric versus monomeric α-catenin link cell junctions to filaments. Commun Biol 2023; 6:276. [PMID: 36928388 PMCID: PMC10020564 DOI: 10.1038/s42003-023-04610-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 02/17/2023] [Indexed: 03/18/2023] Open
Abstract
Attachment between cells is crucial for almost all aspects of the life of cells. These inter-cell adhesions are mediated by the binding of transmembrane cadherin receptors of one cell to cadherins of a neighboring cell. Inside the cell, cadherin binds β-catenin, which interacts with α-catenin. The transitioning of cells between migration and adhesion is modulated by α-catenin, which links cell junctions and the plasma membrane to the actin cytoskeleton. At cell junctions, a single β-catenin/α-catenin heterodimer slips along filamentous actin in the direction of cytoskeletal tension which unfolds clustered heterodimers to form catch bonds with F-actin. Outside cell junctions, α-catenin dimerizes and links the plasma membrane to F-actin. Under cytoskeletal tension, α-catenin unfolds and forms an asymmetric catch bond with F-actin. To understand the mechanism of this important α-catenin function, we determined the 2.7 Å cryogenic electron microscopy (cryoEM) structures of filamentous actin alone and bound to human dimeric α-catenin. Our structures provide mechanistic insights into the role of the α-catenin interdomain interactions in directing α-catenin function and suggest a bivalent mechanism. Further, our cryoEM structure of human monomeric α-catenin provides mechanistic insights into α-catenin autoinhibition. Collectively, our structures capture the initial α-catenin interaction with F-actin before the sensing of force, which is a crucial event in cell adhesion and human disease.
Collapse
Affiliation(s)
| | - Emmanuel W Smith
- The Cell Adhesion Laboratory, UF Scripps, Jupiter, FL, 33458, USA
| | - Tina Izard
- The Cell Adhesion Laboratory, UF Scripps, Jupiter, FL, 33458, USA.
- The Skaggs Graduate School, The Scripps Research Institute, Jupiter, FL, 33458, USA.
| |
Collapse
|
2
|
Rangarajan ES, Izard T. The Cryogenic Electron Microscopy Structure of the Cell Adhesion Regulator Metavinculin Reveals an Isoform-Specific Kinked Helix in Its Cytoskeleton Binding Domain. Int J Mol Sci 2021; 22:E645. [PMID: 33440717 PMCID: PMC7827843 DOI: 10.3390/ijms22020645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 01/08/2021] [Accepted: 01/08/2021] [Indexed: 11/16/2022] Open
Abstract
Vinculin and its heart-specific splice variant metavinculin are key regulators of cell adhesion processes. These membrane-bound cytoskeletal proteins regulate the cell shape by binding to several other proteins at cell-cell and cell-matrix junctions. Vinculin and metavinculin link integrin adhesion molecules to the filamentous actin network. Loss of both proteins prevents cell adhesion and cell spreading and reduces the formation of stress fibers, focal adhesions, or lamellipodia extensions. The binding of talin at cell-matrix junctions or of α-catenin at cell-cell junctions activates vinculin and metavinculin by releasing their autoinhibitory head-tail interaction. Once activated, vinculin and metavinculin bind F-actin via their five-helix bundle tail domains. Unlike vinculin, metavinculin has a 68-amino-acid insertion before the second α-helix of this five-helix F-actin-binding domain. Here, we present the full-length cryogenic electron microscopy structure of metavinculin that captures the dynamics of its individual domains and unveiled a hallmark structural feature, namely a kinked isoform-specific α-helix in its F-actin-binding domain. Our identified conformational landscape of metavinculin suggests a structural priming mechanism that is consistent with the cell adhesion functions of metavinculin in response to mechanical and cellular cues. Our findings expand our understanding of metavinculin function in the heart with implications for the etiologies of cardiomyopathies.
Collapse
Affiliation(s)
| | - Tina Izard
- Cell Adhesion Laboratory, Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, FL 33458, USA;
| |
Collapse
|
3
|
Kanoldt V, Kluger C, Barz C, Schweizer AL, Ramanujam D, Windgasse L, Engelhardt S, Chrostek-Grashoff A, Grashoff C. Metavinculin modulates force transduction in cell adhesion sites. Nat Commun 2020; 11:6403. [PMID: 33335089 PMCID: PMC7747745 DOI: 10.1038/s41467-020-20125-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 11/13/2020] [Indexed: 12/15/2022] Open
Abstract
Vinculin is a ubiquitously expressed protein, crucial for the regulation of force transduction in cells. Muscle cells express a vinculin splice-isoform called metavinculin, which has been associated with cardiomyopathies. However, the molecular function of metavinculin has remained unclear and its role for heart muscle disorders undefined. Here, we have employed a set of piconewton-sensitive tension sensors to probe metavinculin mechanics in cells. Our experiments reveal that metavinculin bears higher molecular forces but is less frequently engaged as compared to vinculin, leading to altered force propagation in cell adhesions. In addition, we have generated knockout mice to investigate the consequences of metavinculin loss in vivo. Unexpectedly, these animals display an unaltered tissue response in a cardiac hypertrophy model. Together, the data reveal that the transduction of cell adhesion forces is modulated by expression of metavinculin, yet its role for heart muscle function seems more subtle than previously thought.
Collapse
Affiliation(s)
- Verena Kanoldt
- Department of Quantitative Cell Biology, Institute of Molecular Cell Biology, University of Münster, 48149, Münster, Germany
- Max Planck Institute of Biochemistry, Group of Molecular Mechanotransduction, 82152, Martinsried, Germany
| | - Carleen Kluger
- Max Planck Institute of Biochemistry, Group of Molecular Mechanotransduction, 82152, Martinsried, Germany
| | - Christiane Barz
- Max Planck Institute of Biochemistry, Group of Molecular Mechanotransduction, 82152, Martinsried, Germany
| | - Anna-Lena Schweizer
- Department of Quantitative Cell Biology, Institute of Molecular Cell Biology, University of Münster, 48149, Münster, Germany
- Max Planck Institute of Biochemistry, Group of Molecular Mechanotransduction, 82152, Martinsried, Germany
| | - Deepak Ramanujam
- Institute of Pharmacology and Toxicology, Technical University of Munich, 80802, Munich, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Munich Heart Alliance, 80802, Munich, Germany
| | - Lukas Windgasse
- Department of Quantitative Cell Biology, Institute of Molecular Cell Biology, University of Münster, 48149, Münster, Germany
| | - Stefan Engelhardt
- Institute of Pharmacology and Toxicology, Technical University of Munich, 80802, Munich, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Munich Heart Alliance, 80802, Munich, Germany
| | - Anna Chrostek-Grashoff
- Department of Quantitative Cell Biology, Institute of Molecular Cell Biology, University of Münster, 48149, Münster, Germany
- Max Planck Institute of Biochemistry, Group of Molecular Mechanotransduction, 82152, Martinsried, Germany
| | - Carsten Grashoff
- Department of Quantitative Cell Biology, Institute of Molecular Cell Biology, University of Münster, 48149, Münster, Germany.
- Max Planck Institute of Biochemistry, Group of Molecular Mechanotransduction, 82152, Martinsried, Germany.
| |
Collapse
|
4
|
Rangarajan ES, Primi MC, Colgan LA, Chinthalapudi K, Yasuda R, Izard T. A distinct talin2 structure directs isoform specificity in cell adhesion. J Biol Chem 2020; 295:12885-12899. [PMID: 32605925 DOI: 10.1074/jbc.ra119.010789] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 06/23/2020] [Indexed: 01/25/2023] Open
Abstract
Integrin receptors regulate normal cellular processes such as signaling, cell migration, adhesion to the extracellular matrix, and leukocyte function. Talin recruitment to the membrane is necessary for its binding to and activation of integrin. Vertebrates have two highly conserved talin homologs that differ in their expression patterns. The F1-F3 FERM subdomains of cytoskeletal proteins resemble a cloverleaf, but in talin1, its F1 subdomain and additional F0 subdomain align more linearly with its F2 and F3 subdomains. Here, we present the talin2 crystal structure, revealing that its F0-F1 di-subdomain displays another unprecedented constellation, whereby the F0-F1-F2 adopts a new cloverleaf-like arrangement. Using multiangle light scattering (MALS), fluorescence lifetime imaging (FLIM), and FRET analyses, we found that substituting the corresponding residues in talin2 that abolish lipid binding in talin1 disrupt the binding of talin to the membrane, focal adhesion formation, and cell spreading. Our results provide the molecular details of the functions of specific talin isoforms in cell adhesion.
Collapse
Affiliation(s)
- Erumbi S Rangarajan
- Cell Adhesion Laboratory, Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, Florida, USA
| | - Marina C Primi
- Cell Adhesion Laboratory, Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, Florida, USA
| | - Lesley A Colgan
- Neuronal Signal Transduction, Max Planck Florida Institute for Neuroscience, Jupiter, Florida, USA
| | - Krishna Chinthalapudi
- Cell Adhesion Laboratory, Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, Florida, USA
| | - Ryohei Yasuda
- Neuronal Signal Transduction, Max Planck Florida Institute for Neuroscience, Jupiter, Florida, USA
| | - Tina Izard
- Cell Adhesion Laboratory, Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, Florida, USA.
| |
Collapse
|
5
|
Krokhotin A, Sarker M, Sevilla EA, Costantini LM, Griffith JD, Campbell SL, Dokholyan NV. Distinct Binding Modes of Vinculin Isoforms Underlie Their Functional Differences. Structure 2019; 27:1527-1536.e3. [PMID: 31422909 PMCID: PMC6774862 DOI: 10.1016/j.str.2019.07.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Revised: 05/23/2019] [Accepted: 07/23/2019] [Indexed: 12/11/2022]
Abstract
Vinculin and its splice isoform metavinculin play key roles in regulating cellular morphology, motility, and force transduction. Vinculin is distinct from metavinculin in its ability to bundle filamentous actin (F-actin). To elucidate the molecular basis for these differences, we employed computational and experimental approaches. Results from these analyses suggest that the C terminus of both vinculin and metavinculin form stable interactions with the F-actin surface. However, the metavinculin tail (MVt) domain contains a 68 amino acid insert, with helix 1 (H1) sequestered into a globular subdomain, which protrudes from the F-actin surface and prevents actin bundling by sterically occluding actin filaments. Consistent with our model, deletion and selective point mutations within the MVt H1 disrupt this protruding structure, and facilitate actin bundling similar to vinculin tail (Vt) domain.
Collapse
Affiliation(s)
- Andrey Krokhotin
- Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Departments of Pathology, Genetics and Developmental Biology, Howard Hughes Medical Institute, Stanford Medical School, Palo Alto, CA 94305, USA
| | - Muzaddid Sarker
- Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Ernesto Alva Sevilla
- Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Lindsey M Costantini
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jack D Griffith
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Sharon L Campbell
- Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
| | - Nikolay V Dokholyan
- Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Departments of Pharmacology and Departments of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA.
| |
Collapse
|
6
|
Lee HT, Sharek L, O’Brien ET, Urbina FL, Gupton SL, Superfine R, Burridge K, Campbell SL. Vinculin and metavinculin exhibit distinct effects on focal adhesion properties, cell migration, and mechanotransduction. PLoS One 2019; 14:e0221962. [PMID: 31483833 PMCID: PMC6726196 DOI: 10.1371/journal.pone.0221962] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 08/19/2019] [Indexed: 12/04/2022] Open
Abstract
Vinculin (Vcn) is a ubiquitously expressed cytoskeletal protein that links transmembrane receptors to actin filaments, and plays a key role in regulating cell adhesion, motility, and force transmission. Metavinculin (MVcn) is a Vcn splice isoform that contains an additional exon encoding a 68-residue insert within the actin binding tail domain. MVcn is selectively expressed at sub-stoichiometic amounts relative to Vcn in smooth and cardiac muscle cells. Mutations in the MVcn insert are linked to various cardiomyopathies. In vitro analysis has previously shown that while both proteins can engage filamentous (F)-actin, only Vcn can promote F-actin bundling. Moreover, we and others have shown that MVcn can negatively regulate Vcn-mediated F-actin bundling in vitro. To investigate functional differences between MVcn and Vcn, we stably expressed either Vcn or MVcn in Vcn-null mouse embryonic fibroblasts. While both MVcn and Vcn were observed at FAs, MVcn-expressing cells had larger but fewer focal adhesions per cell compared to Vcn-expressing cells. MVcn-expressing cells migrated faster and exhibited greater persistence compared to Vcn-expressing cells, even though Vcn-containing FAs assembled and disassembled faster. Magnetic tweezer measurements on Vcn-expressing cells show a typical cell stiffening phenotype in response to externally applied force; however, this was absent in Vcn-null and MVcn-expressing cells. Our findings that MVcn expression leads to larger but fewer FAs per cell, in conjunction with the inability of MVcn to bundle F-actin in vitro and rescue the cell stiffening response, are consistent with our previous findings of actin bundling deficient Vcn variants, suggesting that deficient actin-bundling may account for some of the differences between Vcn and MVcn.
Collapse
Affiliation(s)
- Hyunna T. Lee
- Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Lisa Sharek
- Department of Cell Biology and Physiology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - E. Timothy O’Brien
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Fabio L. Urbina
- Department of Cell Biology and Physiology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Stephanie L. Gupton
- Department of Cell Biology and Physiology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Richard Superfine
- Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Keith Burridge
- Department of Cell Biology and Physiology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Sharon L. Campbell
- Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail:
| |
Collapse
|
7
|
Sarker M, Lee HT, Mei L, Krokhotin A, de Los Reyes SE, Yen L, Costantini LM, Griffith J, Dokholyan NV, Alushin GM, Campbell SL. Cardiomyopathy Mutations in Metavinculin Disrupt Regulation of Vinculin-Induced F-Actin Assemblies. J Mol Biol 2019; 431:1604-1618. [PMID: 30844403 DOI: 10.1016/j.jmb.2019.02.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 02/22/2019] [Accepted: 02/22/2019] [Indexed: 10/27/2022]
Abstract
Debilitating heart conditions, notably dilated and hypertrophic cardiomyopathies (CMs), are associated with point mutations in metavinculin, a larger isoform of the essential cytoskeletal protein vinculin. Metavinculin is co-expressed with vinculin at sub-stoichiometric ratios in cardiac tissues. CM mutations in the metavinculin tail domain (MVt) occur within the extra 68-residue insert that differentiates it from the vinculin tail domain (Vt). Vt binds actin filaments (F-actin) and promotes vinculin dimerization to bundle F-actin into thick fibers. While MVt binds to F-actin in a similar manner to Vt, MVt is incapable of F-actin bundling and inhibits Vt-mediated F-actin bundling. We performed F-actin co-sedimentation and negative-stain EM experiments to dissect the coordinated roles of metavinculin and vinculin in actin fiber assembly and the effects of three known metavinculin CM mutations. These CM mutants were found to weakly induce the formation of disordered F-actin assemblies. Notably, they fail to inhibit Vt-mediated F-actin bundling and instead promote formation of large assemblies embedded with linear bundles. Computational models of MVt bound to F-actin suggest that MVt undergoes a conformational change licensing the formation of a protruding sub-domain incorporating the insert, which sterically prevents dimerization and bundling of F-actin by Vt. Sub-domain formation is destabilized by CM mutations, disrupting this inhibitory mechanism. These findings provide new mechanistic insights into the ability of metavinculin to tune actin organization by vinculin and suggest that dysregulation of this process by CM mutants could underlie their malfunction in disease.
Collapse
Affiliation(s)
- Muzaddid Sarker
- Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Hyunna T Lee
- Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Lin Mei
- Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, NY 10065, USA
| | - Andrey Krokhotin
- Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | | | - Laura Yen
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY 10025, USA
| | - Lindsey M Costantini
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jack Griffith
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Nikolay V Dokholyan
- Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Gregory M Alushin
- Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, NY 10065, USA
| | - Sharon L Campbell
- Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
| |
Collapse
|
8
|
Conformational states during vinculin unlocking differentially regulate focal adhesion properties. Sci Rep 2018; 8:2693. [PMID: 29426917 PMCID: PMC5807537 DOI: 10.1038/s41598-018-21006-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 01/29/2018] [Indexed: 12/22/2022] Open
Abstract
Focal adhesions (FAs) are multi-protein complexes that connect the actin cytoskeleton to the extracellular matrix, via integrin receptors. The growth, stability and adhesive functionality of these structures are tightly regulated by mechanical stress, yet, despite the extensive characterization of the integrin adhesome, the detailed molecular mechanisms underlying FA mechanosensitivity are still unclear. Besides talin, another key candidate for regulating FA-associated mechanosensing, is vinculin, a prominent FA component, which possesses either closed (“auto-inhibited”) or open (“active”) conformation. A direct experimental demonstration, however, of the conformational transition between the two states is still absent. In this study, we combined multiple structural and biological approaches to probe the transition from the auto-inhibited to the active conformation, and determine its effects on FA structure and dynamics. We further show that the transition from a closed to an open conformation requires two sequential steps that can differentially regulate FA growth and stability.
Collapse
|
9
|
Sun L, Noel JK, Levine H, Onuchic JN. Molecular Simulations Suggest a Force-Dependent Mechanism of Vinculin Activation. Biophys J 2017; 113:1697-1710. [PMID: 29045864 DOI: 10.1016/j.bpj.2017.08.037] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 07/19/2017] [Accepted: 08/08/2017] [Indexed: 10/18/2022] Open
Abstract
Focal adhesions are dynamic constructs at the leading edge of migrating cells, linking them to the extracellular matrix and enabling force sensing and transmission. The lifecycle of a focal adhesion is a highly coordinated process involving spatial and temporal variations of protein composition, interaction, and cellular tension. The assembly of focal adhesions requires the recruitment and activation of vinculin. Vinculin is present in the cytoplasm in an autoinhibited conformation in which its tail is held pincerlike by its head domains, further stabilized by two high-affinity head-tail interfaces. Vinculin has binding sites for talin and F-actin, but effective binding requires vinculin activation to release its head-tail associations. In migrating cells, it has been shown that the locations of vinculin activation coincide with areas of high cellular tension, and that the highest recorded tensions across vinculin are associated with adhesion assembly. Here, we use a structure-based model to investigate vinculin activation by talin modulated by tensile force generated by transient associations with F-actin. We show that vinculin activation may proceed from an intermediate state stabilized by partial talin-vinculin association. There is a low-force regime and a high-force regime where vinculin activation is dominated by two different pathways with distinct responses to force. Specifically, at zero or low forces, vinculin activation requires substantial destabilization of the main head-tail interface, which is rigid and undergoes very limited fluctuations, despite the other being relatively flexible. This pathway is not significantly affected by force; instead, higher forces favor an alternative pathway, which seeks to release the vinculin tail from its pincerlike head domains before destabilizing the head-tail interfaces. This pathway has a force-sensitive activation barrier and is significantly accelerated by force. Experimental data of vinculin during various stages of the focal adhesion lifecycle are consistent with the proposed force-regulated activation pathway.
Collapse
Affiliation(s)
- Li Sun
- Center for Theoretical Biological Physics, Rice University, Houston, Texas
| | - Jeffrey K Noel
- Center for Theoretical Biological Physics, Rice University, Houston, Texas; Max Delbrück Center, Berlin, Germany
| | - Herbert Levine
- Center for Theoretical Biological Physics, Rice University, Houston, Texas
| | - José N Onuchic
- Center for Theoretical Biological Physics, Rice University, Houston, Texas.
| |
Collapse
|
10
|
Ittisoponpisan S, Alhuzimi E, Sternberg MJE, David A. Landscape of Pleiotropic Proteins Causing Human Disease: Structural and System Biology Insights. Hum Mutat 2017; 38:289-296. [PMID: 27957775 DOI: 10.1002/humu.23155] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 12/03/2016] [Indexed: 12/13/2022]
Abstract
Pleiotropy is the phenomenon by which the same gene can result in multiple phenotypes. Pleiotropic proteins are emerging as important contributors to rare and common disorders. Nevertheless, little is known on the mechanisms underlying pleiotropy and the characteristic of pleiotropic proteins. We analyzed disease-causing proteins reported in UniProt and observed that 12% are pleiotropic (variants in the same protein cause more than one disease). Pleiotropic proteins were enriched in deleterious and rare variants, but not in common variants. Pleiotropic proteins were more likely to be involved in the pathogenesis of neoplasms, neurological, and circulatory diseases and congenital malformations, whereas non-pleiotropic proteins in endocrine and metabolic disorders. Pleiotropic proteins were more essential and had a higher number of interacting partners compared with non-pleiotropic proteins. Significantly more pleiotropic than non-pleiotropic proteins contained at least one intrinsically long disordered region (P < 0.001). Deleterious variants occurring in structurally disordered regions were more commonly found in pleiotropic, rather than non-pleiotropic proteins. In conclusion, pleiotropic proteins are an important contributor to human disease. They represent a biologically different class of proteins compared with non-pleiotropic proteins and a better understanding of their characteristics and genetic variants can greatly aid in the interpretation of genetic studies and drug design.
Collapse
Affiliation(s)
- Sirawit Ittisoponpisan
- Structural Bioinformatics Group, Department of Life Sciences, Imperial College London, London, UK
| | - Eman Alhuzimi
- Structural Bioinformatics Group, Department of Life Sciences, Imperial College London, London, UK
| | - Michael J E Sternberg
- Structural Bioinformatics Group, Department of Life Sciences, Imperial College London, London, UK
| | - Alessia David
- Structural Bioinformatics Group, Department of Life Sciences, Imperial College London, London, UK
| |
Collapse
|
11
|
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.
Collapse
|
12
|
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.
Collapse
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
| |
Collapse
|
13
|
Kim LY, Thompson PM, Lee HT, Pershad M, Campbell SL, Alushin GM. The Structural Basis of Actin Organization by Vinculin and Metavinculin. J Mol Biol 2015; 428:10-25. [PMID: 26493222 DOI: 10.1016/j.jmb.2015.09.031] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 09/23/2015] [Accepted: 09/25/2015] [Indexed: 11/30/2022]
Abstract
Vinculin is an essential adhesion protein that links membrane-bound integrin and cadherin receptors through their intracellular binding partners to filamentous actin, facilitating mechanotransduction. Here we present an 8.5-Å-resolution cryo-electron microscopy reconstruction and pseudo-atomic model of the vinculin tail (Vt) domain bound to F-actin. Upon actin engagement, the N-terminal "strap" and helix 1 are displaced from the Vt helical bundle to mediate actin bundling. We find that an analogous conformational change also occurs in the H1' helix of the tail domain of metavinculin (MVt) upon actin binding, a muscle-specific splice isoform that suppresses actin bundling by Vt. These data support a model in which metavinculin tunes the actin bundling activity of vinculin in a tissue-specific manner, providing a mechanistic framework for understanding metavinculin mutations associated with hereditary cardiomyopathies.
Collapse
Affiliation(s)
- Laura Y Kim
- Laboratory of Macromolecular Interactions, Cell Biology and Physiology Center, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Peter M Thompson
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Hyunna T Lee
- 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
| | - Sharon L Campbell
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Gregory M Alushin
- Laboratory of Macromolecular Interactions, Cell Biology and Physiology Center, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
| |
Collapse
|
14
|
Oztug Durer ZA, McGillivary RM, Kang H, Elam WA, Vizcarra CL, Hanein D, De La Cruz EM, Reisler E, Quinlan ME. Metavinculin Tunes the Flexibility and the Architecture of Vinculin-Induced Bundles of Actin Filaments. J Mol Biol 2015; 427:2782-98. [PMID: 26168869 DOI: 10.1016/j.jmb.2015.07.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 07/06/2015] [Accepted: 07/07/2015] [Indexed: 11/19/2022]
Abstract
Vinculin is an abundant protein found at cell-cell and cell-extracellular matrix junctions. In muscles, a longer splice isoform of vinculin, metavinculin, is also expressed. The metavinculin-specific insert is part of the C-terminal tail domain, the actin-binding site of both isoforms. Mutations in the metavinculin-specific insert are linked to heart disease such as dilated cardiomyopathies. Vinculin tail domain (VT) both binds and bundles actin filaments. Metavinculin tail domain (MVT) binds actin filaments in a similar orientation but does not bundle filaments. Recently, MVT was reported to sever actin filaments. In this work, we asked how MVT influences F-actin alone or in combination with VT. Cosedimentation and limited proteolysis experiments indicated a similar actin binding affinity and mode for both VT and MVT. In real-time total internal reflection fluorescence microscopy experiments, MVT's severing activity was negligible. Instead, we found that MVT binding caused a 2-fold reduction in F-actin's bending persistence length and increased susceptibility to breakage. Using mutagenesis and site-directed labeling with fluorescence probes, we determined that MVT alters actin interprotomer contacts and dynamics, which presumably reflect the observed changes in bending persistence length. Finally, we found that MVT decreases the density and thickness of actin filament bundles generated by VT. Altogether, our data suggest that MVT alters actin filament flexibility and tunes filament organization in the presence of VT. Both of these activities are potentially important for muscle cell function. Perhaps MVT allows the load of muscle contraction to act as a signal to reorganize actin filaments.
Collapse
Affiliation(s)
- Zeynep A Oztug Durer
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095-1569, USA
| | - Rebecca M McGillivary
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095-1569, USA
| | - Hyeran Kang
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA
| | - W Austin Elam
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA
| | - Christina L Vizcarra
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095-1569, USA
| | - Dorit Hanein
- Bioinformatics and Structural Biology Program, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
| | - Enrique M De La Cruz
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA
| | - Emil Reisler
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095-1569, USA; Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095-1570, USA
| | - Margot E Quinlan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095-1569, USA; Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095-1570, USA.
| |
Collapse
|
15
|
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.
Collapse
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
| |
Collapse
|
16
|
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.
Collapse
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
| |
Collapse
|
17
|
Yogesha SD, Sharff A, Bricogne G, Izard T. Intermolecular versus intramolecular interactions of the vinculin binding site 33 of talin. Protein Sci 2013; 20:1471-6. [PMID: 21648001 DOI: 10.1002/pro.671] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The cytoskeletal proteins talin and vinculin are localized at cell-matrix junctions and are key regulators of cell signaling, adhesion, and migration. Talin couples integrins via its FERM domain to F-actin and is an important regulator of integrin activation and clustering. The 220 kDa talin rod domain comprises several four- and five-helix bundles that harbor amphipathic α-helical vinculin binding sites (VBSs). In its inactive state, the hydrophobic VBS residues involved in binding to vinculin are buried within these helix bundles, and the mechanical force emanating from bound integrin receptors is thought necessary for their release and binding to vinculin. The crystal structure of a four-helix bundle of talin that harbors one of these VBSs, coined VBS33, was recently determined. Here we report the crystal structure of VBS33 in complex with vinculin at 2 Å resolution. Notably, comparison of the apo and vinculin bound structures shows that intermolecular interactions of the VBS33 α-helix with vinculin are more extensive than the intramolecular interactions of the VBS33 within the talin four-helix bundle.
Collapse
Affiliation(s)
- S D Yogesha
- Cell Adhesion Laboratory, Department of Cancer Biology, The Scripps Research Institute, Jupiter, FL 33458, USA
| | | | | | | |
Collapse
|
18
|
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]
|
19
|
Rangarajan ES, Izard T. Dimer asymmetry defines α-catenin interactions. Nat Struct Mol Biol 2013; 20:188-93. [PMID: 23292143 PMCID: PMC3805043 DOI: 10.1038/nsmb.2479] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Accepted: 11/27/2012] [Indexed: 01/19/2023]
Abstract
The F-actin binding cytoskeletal protein α-catenin interacts with
β-catenin-cadherin complexes and stabilizes cell-cell junctions. The
β-catenin–α-catenin complex cannot bind to F-actin,
whereas interactions of α-catenin with the cytoskeletal protein vinculin
appear necessary to stabilize adherens junctions. Here we report the crystal
structure of nearly full-length human α-catenin at 3.7 Å
resolution. α-Catenin forms an asymmetric dimer, where the four-helix
bundle domains of each subunit engage in distinct intermolecular interactions.
This results in a left handshake-like dimer, where the two subunits have
remarkably different conformations. The crystal structure explains why dimeric
α-catenin has a higher affinity for F-actin than monomeric
α-catenin, why the β-catenin–α-catenin complex
does not bind to F-actin, how activated vinculin links the cadherin-catenin
complex to the cytoskeleton, and why α-catenin but not inactive vinculin
can bind to F-actin.
Collapse
Affiliation(s)
- Erumbi S Rangarajan
- Department of Cancer Biology, Scripps Research Institute, Jupiter, Florida, USA
| | | |
Collapse
|
20
|
Maiden SL, Harrison N, Keegan J, Cain B, Lynch AM, Pettitt J, Hardin J. Specific conserved C-terminal amino acids of Caenorhabditis elegans HMP-1/α-catenin modulate F-actin binding independently of vinculin. J Biol Chem 2012; 288:5694-706. [PMID: 23271732 DOI: 10.1074/jbc.m112.438093] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Stable intercellular adhesions formed through the cadherin-catenin complex are important determinants of proper tissue architecture and help maintain tissue integrity during morphogenetic movements in developing embryos. A key regulator of this stability is α-catenin, which connects the cadherin-catenin complex to the actin cytoskeleton. Although the C-terminal F-actin-binding domain of α-catenin has been shown to be crucial for its function, a more detailed in vivo analysis of discrete regions and residues required for actin binding has not been performed. Using Caenorhabditis elegans as a model system, we have characterized mutations in hmp-1/α-catenin that identify HMP-1 residues 687-742 and 826-927, as well as amino acid 802, as critical to the localization of junctional proximal actin during epidermal morphogenesis. We also find that the S823F transition in a hypomorphic allele, hmp-1(fe4), decreases actin binding in vitro. Using hmp-1(fe4) animals in a mutagenesis screen, we were then able to identify 11 intragenic suppressors of hmp-1(fe4) that revert actin binding to wild-type levels. Using homology modeling, we show that these amino acids are positioned at key conserved sites within predicted α-helices in the C terminus. Through the use of transgenic animals, we also demonstrate that HMP-1 residues 315-494, which correspond to a putative mechanotransduction domain that binds vinculin in vertebrate αE-catenin, are not required during epidermal morphogenesis but may aid efficient recruitment of HMP-1 to the junction. Our studies are the first to identify key conserved amino acids in the C terminus of α-catenin that modulate F-actin binding in living embryos of a simple metazoan.
Collapse
Affiliation(s)
- Stephanie L Maiden
- Department of Zoology, University of Wisconsin, Madison, Wisconsin 53706, USA
| | | | | | | | | | | | | |
Collapse
|
21
|
Thoss F, Dietrich F, Punkt K, Illenberger S, Rottner K, Himmel M, Ziegler WH. Metavinculin: New insights into functional properties of a muscle adhesion protein. Biochem Biophys Res Commun 2012; 430:7-13. [PMID: 23159629 DOI: 10.1016/j.bbrc.2012.11.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 11/04/2012] [Indexed: 11/16/2022]
Abstract
Metavinculin is a muscle-specific splice variant of the ubiquitously expressed cytoskeletal adaptor protein vinculin. Both proteins are thought to be co-expressed in all muscle types where they co-localize to microfilament-associated adhesion sites. It has been shown that a metavinculin-specific insertion of 68 amino acids alters the biochemical properties of the five-helix bundle in the tail domain. Here, we demonstrate that the metavinculin-specific helix H1' plays an important role for protein stability of the tail domain, since a point mutation in this helix, R975W, which is associated with the occurrence of dilated cardiomyopathy in man, further decreases thermal stability of the metavinculin tail domain. In striated muscle progenitor cells (myoblasts), both, metavinculin and the R975W mutant show significantly reduced, albeit distinctive residency and exchange rates in adhesion sites as compared to vinculin. In contrast to previous studies, we show that metavinculin is localized in a muscle fiber type-dependent fashion to the costameres of striated muscle, reflecting the individual metabolic and physiological status of a given muscle fiber. Metavinculin expression is highest in fast, glycolytic muscle fibers and virtually absent in M. diaphragmaticus, a skeletal muscle entirely lacking fast, glycolytic fibers. In summary, our data suggest that metavinculin enrichment in attachment sites of muscle cells leads to higher mechanical stability of adhesion complexes allowing for greater shear force resistance.
Collapse
Affiliation(s)
- Florian Thoss
- Interdisciplinary Center for Clinical Research (IZKF) Leipzig, Faculty of Medicine, University of Leipzig, D-04103 Leipzig, Germany
| | | | | | | | | | | | | |
Collapse
|
22
|
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.
Collapse
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.
| |
Collapse
|
23
|
Janssen MEW, Liu H, Volkmann N, Hanein D. The C-terminal tail domain of metavinculin, vinculin's splice variant, severs actin filaments. ACTA ACUST UNITED AC 2012; 197:585-93. [PMID: 22613835 PMCID: PMC3365496 DOI: 10.1083/jcb.201111046] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Relative to vinculin, a unique 68-residue insert in the C-terminal tail of metavinculin results in a loss of actin filament-bundling activity but gain of actin filament-severing activity. Vinculin and its splice variant, metavinculin (MV), are key elements of multiple protein assemblies linking the extracellular matrix to the actin cytoskeleton. Vinculin is expressed ubiquitously, whereas MV is mainly expressed in smooth and cardiac muscle tissue. The only difference in amino acid sequence between the isoforms is a 68-residue insert in the C-terminal tail domain of MV (MVt). Although the functional role of this insert remains elusive, its importance is exemplified by point mutations that are associated with dilated and hypertrophic cardiomyopathy. In vinculin, the actin binding site resides in the tail domain. In this paper, we show that MVt binds actin filaments similarly to the vinculin tail domain. Unlike its splice variant, MVt did not bundle actin filaments. Instead, MVt promoted severing of actin filaments, most efficiently at substoichiometric concentrations. This surprising and seemingly contradictory alteration of vinculin function by the 68-residue insert may be essential for modulating compliance of vinculin-induced actin bundles when exposed to rapidly increasing external forces.
Collapse
Affiliation(s)
- Mandy E W Janssen
- Bioinformatics and Systems Biology Program, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
| | | | | | | |
Collapse
|
24
|
Yogesha SD, Rangarajan ES, Vonrhein C, Bricogne G, Izard T. Crystal structure of vinculin in complex with vinculin binding site 50 (VBS50), the integrin binding site 2 (IBS2) of talin. Protein Sci 2012; 21:583-8. [PMID: 22334306 DOI: 10.1002/pro.2041] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 02/01/2012] [Accepted: 02/02/2012] [Indexed: 11/06/2022]
Abstract
The cytoskeletal protein talin activates integrin receptors by binding of its FERM domain to the cytoplasmic tail of β-integrin. Talin also couples integrins to the actin cytoskeleton, largely by binding to and activating the cytoskeletal protein vinculin, which binds to F-actin through the agency of its five-helix bundle tail (Vt) domain. Talin activates vinculin by means of buried amphipathic α-helices coined vinculin binding sites (VBSs) that reside within numerous four- and five-helix bundle domains that comprise the central talin rod, which are released from their buried locales by means of mechanical tension on the integrin:talin complex. In turn, these VBSs bind to the N-terminal seven-helix bundle (Vh1) domain of vinculin, creating an entirely new helix bundle that severs its head-tail interactions. Interestingly, talin harbors a second integrin binding site coined IBS2 that consists of two five-helix bundle domains that also contain a VBS (VBS50). Here we report the crystal structure of VBS50 in complex with vinculin at 2.3 Å resolution and show that intramolecular interactions of VBS50 within IBS2 are much more extensive versus its interactions with vinculin. Indeed, the IBS2-vinculin interaction only occurs at physiological temperature and the affinity of VBS50 for vinculin is about 30 times less than other VBSs. The data support a model where integrin binding destabilizes IBS2 to allow it to bind to vinculin.
Collapse
Affiliation(s)
- S D Yogesha
- Department of Cancer Biology, Cell Adhesion Laboratory, The Scripps Research Institute, Jupiter, Florida 33458, USA
| | | | | | | | | |
Collapse
|
25
|
Park H, Lee JH, Gouin E, Cossart P, Izard T. The rickettsia surface cell antigen 4 applies mimicry to bind to and activate vinculin. J Biol Chem 2011; 286:35096-103. [PMID: 21841197 DOI: 10.1074/jbc.m111.263855] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pathogenic Rickettsia species cause high morbidity and mortality, especially R. prowazekii, the causative agent of typhus. Like many intracellular pathogens, Rickettsia exploit the cytoskeleton to enter and spread within the host cell. Here we report that the cell surface antigen sca4 of Rickettsia co-localizes with vinculin in cells at sites of focal adhesions in sca4-transfected cells and that sca4 binds to and activates vinculin through two vinculin binding sites (VBSs) that are conserved across all Rickettsia. Remarkably, this occurs through molecular mimicry of the vinculin-talin interaction that is also seen with the IpaA invasin of the intracellular pathogen Shigella, where binding of these VBSs to the vinculin seven-helix bundle head domain (Vh1) displaces intramolecular interactions with the vinculin tail domain that normally clamp vinculin in an inactive state. Finally, the vinculin·sca4-VBS crystal structures reveal that vinculin adopts a new conformation when bound to the C-terminal VBS of sca4. Collectively, our data define the mechanism by which sca4 activates vinculin and interacts with the actin cytoskeleton, and they suggest important roles for vinculin in Rickettsia pathogenesis.
Collapse
Affiliation(s)
- HaJeung Park
- Cell Adhesion Laboratory, Department of Cancer Biology, The Scripps Research Institute, Jupiter, Florida 33458, USA
| | | | | | | | | |
Collapse
|
26
|
Park H, Valencia-Gallardo C, Sharff A, Van Nhieu GT, Izard T. Novel vinculin binding site of the IpaA invasin of Shigella. J Biol Chem 2011; 286:23214-21. [PMID: 21525010 PMCID: PMC3123088 DOI: 10.1074/jbc.m110.184283] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2010] [Revised: 04/05/2011] [Indexed: 11/06/2022] Open
Abstract
Internalization of Shigella into host epithelial cells, where the bacteria replicates and spreads to neighboring cells, requires a type 3 secretion system (T3SS) effector coined IpaA. IpaA binds directly to and activates the cytoskeletal protein vinculin after injection in the host cell cytosol, and this was previously thought to be directed by two amphipathic α-helical vinculin-binding sites (VBS) found in the C-terminal tail domain of IpaA. Here, we report a third VBS, IpaA-VBS3, that is located N-terminal to the other two VBSs of IpaA and show that one IpaA molecule can bind up to three vinculin molecules. Biochemical in vitro Shigella invasion assays and the 1.6 Å crystal structure of the vinculin·IpaA-VBS3 complex showed that IpaA-VBS3 is functionally redundant with the other two IpaA-VBSs in cell invasion and in activating the latent F-actin binding functions of vinculin. Multiple VBSs in IpaA are reminiscent of talin, which harbors 11 VBSs. However, most of the talin VBSs have low affinity and are buried in helix bundles, whereas all three of the VBSs of IpaA are high affinity, readily available, and in close proximity to each other in the IpaA structure. Although deletion of IpaA-VBS3 has no detectable effects on Shigella invasion of epithelial cells, deletion of all three VBSs impaired bacterial invasion to levels found in an ipaA null mutant strain. Thus, IpaA-directed mimicry of talin in activating vinculin occurs through three high affinity VBSs that are essential for Shigella pathogenesis.
Collapse
Affiliation(s)
- HaJeung Park
- From the Cell Adhesion Laboratory, Department of Cancer Biology, Scripps Research Institute, Jupiter, Florida 33458
| | - Cesar Valencia-Gallardo
- the Unité de Communication Intercellulaire et Infections Microbiennes, Inserm U971, Collège de France, 75005 Paris Cedex, France, and
| | - Andrew Sharff
- Global Phasing Ltd., Sheraton House, Castle Park, Cambridge CB3 0AX, United Kingdom
| | - Guy Tran Van Nhieu
- the Unité de Communication Intercellulaire et Infections Microbiennes, Inserm U971, Collège de France, 75005 Paris Cedex, France, and
| | - Tina Izard
- From the Cell Adhesion Laboratory, Department of Cancer Biology, Scripps Research Institute, Jupiter, Florida 33458
| |
Collapse
|
27
|
Rangarajan ES, Lee JH, Izard T. Apo raver1 structure reveals distinct RRM domain orientations. Protein Sci 2011; 20:1464-70. [PMID: 21633983 DOI: 10.1002/pro.664] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Accepted: 05/06/2011] [Indexed: 11/08/2022]
Abstract
Raver1 is a multifunctional protein that modulates both alternative splicing and focal adhesion assembly by binding to the nucleoplasmic splicing repressor polypyrimidine tract protein (PTB) or to the cytoskeletal proteins vinculin and α-actinin. The amino-terminal region of raver1 has three RNA recognition motif (RRM1, RRM2, and RRM3) domains, and RRM1 interacts with the vinculin tail (Vt) domain and vinculin mRNA. We previously determined the crystal structure of the raver1 RRM1-3 domains in complex with Vt at 2.75 Å resolution. Here, we report crystal structure of the unbound raver1 RRM1-3 domains at 2 Å resolution. The apo structure reveals that a bound sulfate ion disrupts an electrostatic interaction between the RRM1 and RRM2 domains, triggering a large relative domain movement of over 30°. Superposition with other RNA-bound RRM structures places the sulfate ion near the superposed RNA phosphate group suggesting that this is the raver1 RNA binding site. While several single and some tandem RRM domain structures have been described, to the best of our knowledge, this is the second report of a three-tandem RRM domain structure.
Collapse
Affiliation(s)
- Erumbi S Rangarajan
- Cell Adhesion Laboratory, Department of Cancer Biology, The Scripps Research Institute, Jupiter, Florida 33458, USA
| | | | | |
Collapse
|