1
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Lorenz C, Köster S. Multiscale architecture: Mechanics of composite cytoskeletal networks. BIOPHYSICS REVIEWS 2022; 3:031304. [PMID: 38505277 PMCID: PMC10903411 DOI: 10.1063/5.0099405] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 07/27/2022] [Indexed: 03/21/2024]
Abstract
Different types of biological cells respond differently to mechanical stresses, and these responses are mainly governed by the cytoskeleton. The main components of this biopolymer network are actin filaments, microtubules, and intermediate filaments, whose mechanical and dynamic properties are highly distinct, thus opening up a large mechanical parameter space. Aside from experiments on whole, living cells, "bottom-up" approaches, utilizing purified, reconstituted protein systems, tremendously help to shed light on the complex mechanics of cytoskeletal networks. Such experiments are relevant in at least three aspects: (i) from a fundamental point of view, cytoskeletal networks provide a perfect model system for polymer physics; (ii) in materials science and "synthetic cell" approaches, one goal is to fully understand properties of cellular materials and reconstitute them in synthetic systems; (iii) many diseases are associated with cell mechanics, so a thorough understanding of the underlying phenomena may help solving pressing biomedical questions. In this review, we discuss the work on networks consisting of one, two, or all three types of filaments, entangled or cross-linked, and consider active elements such as molecular motors and dynamically growing filaments. Interestingly, tuning the interactions among the different filament types results in emergent network properties. We discuss current experimental challenges, such as the comparability of different studies, and recent methodological advances concerning the quantification of attractive forces between filaments and their influence on network mechanics.
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Affiliation(s)
- C. Lorenz
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - S. Köster
- Author to whom correspondence should be addressed:
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2
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Multiscale mechanics and temporal evolution of vimentin intermediate filament networks. Proc Natl Acad Sci U S A 2021; 118:2102026118. [PMID: 34187892 DOI: 10.1073/pnas.2102026118] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The cytoskeleton, an intricate network of protein filaments, motor proteins, and cross-linkers, largely determines the mechanical properties of cells. Among the three filamentous components, F-actin, microtubules, and intermediate filaments (IFs), the IF network is by far the most extensible and resilient to stress. We present a multiscale approach to disentangle the three main contributions to vimentin IF network mechanics-single-filament mechanics, filament length, and interactions between filaments-including their temporal evolution. Combining particle tracking, quadruple optical trapping, and computational modeling, we derive quantitative information on the strength and kinetics of filament interactions. Specifically, we find that hydrophobic contributions to network mechanics enter mostly via filament-elongation kinetics, whereas electrostatics have a direct influence on filament-filament interactions.
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3
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Molecular Insight into the Regulation of Vimentin by Cysteine Modifications and Zinc Binding. Antioxidants (Basel) 2021; 10:antiox10071039. [PMID: 34203497 PMCID: PMC8300659 DOI: 10.3390/antiox10071039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Revised: 06/20/2021] [Accepted: 06/24/2021] [Indexed: 01/11/2023] Open
Abstract
The intermediate filament protein vimentin is involved in essential cellular processes, including cell division and stress responses, as well as in the pathophysiology of cancer, pathogen infection, and autoimmunity. The vimentin network undergoes marked reorganizations in response to oxidative stress, in which modifications of vimentin single cysteine residue, Cys328, play an important role, and is modulated by zinc availability. However, the molecular basis for this regulation is not fully understood. Here, we show that Cys328 displays a low pKa, supporting its reactivity, and is readily alkylated and oxidized in vitro. Moreover, combined oxidation and crosslinking assays and molecular dynamics simulations support that zinc ions interact with Cys328 in its thiolate form, whereas Glu329 and Asp331 stabilize zinc coordination. Vimentin oxidation can induce disulfide crosslinking, implying the close proximity of Cys328 from neighboring dimers in certain vimentin conformations, supported by our computational models. Notably, micromolar zinc concentrations prevent Cys328 alkylation, lipoxidation, and disulfide formation. Moreover, zinc selectively protects vimentin from crosslinking using short-spacer cysteine-reactive but not amine-reactive agents. These effects are not mimicked by magnesium, consistent with a lower number of magnesium ions hosted at the cysteine region, according to molecular dynamics simulations. Importantly, the region surrounding Cys328 is involved in interaction with several drugs targeting vimentin and is conserved in type III intermediate filaments, which include glial fibrillary acidic protein and desmin. Altogether, our results identify this region as a hot spot for zinc binding, which modulates Cys328 reactivity. Moreover, they provide a molecular standpoint for vimentin regulation through the interplay between cysteine modifications and zinc availability.
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4
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Vimentin intermediate filaments stabilize dynamic microtubules by direct interactions. Nat Commun 2021; 12:3799. [PMID: 34145230 PMCID: PMC8213705 DOI: 10.1038/s41467-021-23523-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 04/13/2021] [Indexed: 12/23/2022] Open
Abstract
The cytoskeleton determines cell mechanics and lies at the heart of important cellular functions. Growing evidence suggests that the manifold tasks of the cytoskeleton rely on the interactions between its filamentous components-actin filaments, intermediate filaments, and microtubules. However, the nature of these interactions and their impact on cytoskeletal dynamics are largely unknown. Here, we show in a reconstituted in vitro system that vimentin intermediate filaments stabilize microtubules against depolymerization and support microtubule rescue. To understand these stabilizing effects, we directly measure the interaction forces between individual microtubules and vimentin filaments. Combined with numerical simulations, our observations provide detailed insight into the physical nature of the interactions and how they affect microtubule dynamics. Thus, we describe an additional, direct mechanism by which cells establish the fundamental cross talk of cytoskeletal components alongside linker proteins. Moreover, we suggest a strategy to estimate the binding energy of tubulin dimers within the microtubule lattice.
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5
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Pulling the springs of a cell by single-molecule force spectroscopy. Emerg Top Life Sci 2021; 5:77-87. [PMID: 33284963 DOI: 10.1042/etls20200254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 11/11/2020] [Accepted: 11/16/2020] [Indexed: 11/17/2022]
Abstract
The fundamental unit of the human body comprises of the cells which remain embedded in a fibrillar network of extracellular matrix proteins which in turn provides necessary anchorage the cells. Tissue repair, regeneration and reprogramming predominantly involve a traction force mediated signalling originating in the ECM and travelling deep into the cell including the nucleus via circuitry of spring-like filamentous proteins like microfilaments or actin, intermediate filaments and microtubules to elicit a response in the form of mechanical movement as well as biochemical changes. The 'springiness' of these proteins is highlighted in their extension-contraction behaviour which is manifested as an effect of differential traction force. Atomic force microscope (AFM) provides the magic eye to visualize and quantify such force-extension/indentation events in these filamentous proteins as well as in whole cells. In this review, we have presented a summary of the current understanding and advancement of such measurements by AFM based single-molecule force spectroscopy in the context of cytoskeletal and nucleoskeletal proteins which act in tandem to facilitate mechanotransduction.
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6
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Cruz K, Wang YH, Oake SA, Janmey PA. Polyelectrolyte Gels Formed by Filamentous Biopolymers: Dependence of Crosslinking Efficiency on the Chemical Softness of Divalent Cations. Gels 2021; 7:41. [PMID: 33917686 PMCID: PMC8167600 DOI: 10.3390/gels7020041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 04/02/2021] [Accepted: 04/04/2021] [Indexed: 01/21/2023] Open
Abstract
Filamentous anionic polyelectrolytes are common in biological materials. Some examples are the cytoskeletal filaments that assemble into networks and bundled structures to give the cell mechanical resistance and that act as surfaces on which enzymes and other molecules can dock. Some viruses, especially bacteriophages are also long thin polyelectrolytes, and their bending stiffness is similar to those of the intermediate filament class of cytoskeletal polymers. These relatively stiff, thin, and long polyelectrolytes have charge densities similar to those of more flexible polyelectrolytes such as DNA, hyaluronic acid, and polyacrylates, and they can form interpenetrating networks and viscoelastic gels at volume fractions far below those at which more flexible polymers form hydrogels. In this report, we examine how different types of divalent and multivalent counterions interact with two biochemically different but physically similar filamentous polyelectrolytes: Pf1 virus and vimentin intermediate filaments (VIF). Different divalent cations aggregate both polyelectrolytes similarly, but transition metal ions are more efficient than alkaline earth ions and their efficiency increases with increasing atomic weight. Comparison of these two different types of polyelectrolyte filaments enables identification of general effects of counterions with polyelectrolytes and can identify cases where the interaction of the counterions and the filaments exhibits stronger and more specific interactions than those of counterion condensation.
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Affiliation(s)
- Katrina Cruz
- Department of Physiology, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA 19063, USA; (K.C.); (Y.-H.W.); (S.A.O.)
| | - Yu-Hsiu Wang
- Department of Physiology, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA 19063, USA; (K.C.); (Y.-H.W.); (S.A.O.)
- Department Biochemistry and Molecular Biology, University of Texas Medical Branch, Rm 6.160, 11th and Mechanic St., Medical Research Building, Galveston, TX 77555, USA
| | - Shaina A. Oake
- Department of Physiology, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA 19063, USA; (K.C.); (Y.-H.W.); (S.A.O.)
| | - Paul A. Janmey
- Department of Physiology, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA 19063, USA; (K.C.); (Y.-H.W.); (S.A.O.)
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7
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Murakami K, Sato M, Miyasaka Y, Hatori K. Selective association of desmin intermediate filaments with a phospholipid layer in droplets. Biochem Biophys Res Commun 2021; 555:109-114. [PMID: 33813269 DOI: 10.1016/j.bbrc.2021.03.131] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Accepted: 03/24/2021] [Indexed: 10/24/2022]
Abstract
Desmin, an intermediate filament protein expressed in muscle cells, plays a key role in the integrity and regulation of the contractile system. Furthermore, the distribution of desmin in cells and its interplay with plasma and organelle membranes are crucial for cell functions; however, the fundamental properties of lipid-desmin interactions remain unknown. Using a water-in-oil method for a limited space system in vitro, we examined the distribution of desmin in three types of phospholipid droplets: 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), and 1,2-dioleoyl-sn-glycero-3-phosphoserine (DOPS). When fluorescent-labeled desmin was observed for 60 min after desmin assembly was initiated by adding 25 mM KCl, desmin accumulated on both the DOPE and DOPS layers; however, it did not accumulate on the DOPC layer of droplets. An increase in salt concentration did not moderate the accumulation. The initial form of either oligomer or mature filament affected the accumulation on each lipid layer. When liposomes were included in the droplets, desmin was associated with DOPE but not on DOPC liposomes. These results suggest that desmin has the potential for association with phospholipids concerning desmin form and lipid shape. The behavior and composition of living membranes may affect the distribution of desmin networks.
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Affiliation(s)
- Keigo Murakami
- Department of Bio-Systems Engineering, Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jyonan, Yonezawa, 992-8510, Japan
| | - Masashi Sato
- Department of Bio-Systems Engineering, Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jyonan, Yonezawa, 992-8510, Japan
| | - Yoshiya Miyasaka
- Department of Bio-Systems Engineering, Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jyonan, Yonezawa, 992-8510, Japan
| | - Kuniyuki Hatori
- Department of Bio-Systems Engineering, Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jyonan, Yonezawa, 992-8510, Japan.
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8
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Patteson AE, Carroll RJ, Iwamoto DV, Janmey PA. The vimentin cytoskeleton: when polymer physics meets cell biology. Phys Biol 2020; 18:011001. [PMID: 32992303 PMCID: PMC8240483 DOI: 10.1088/1478-3975/abbcc2] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The proper functions of tissues depend on the ability of cells to withstand stress and maintain shape. Central to this process is the cytoskeleton, comprised of three polymeric networks: F-actin, microtubules, and intermediate filaments (IFs). IF proteins are among the most abundant cytoskeletal proteins in cells; yet they remain some of the least understood. Their structure and function deviate from those of their cytoskeletal partners, F-actin and microtubules. IF networks show a unique combination of extensibility, flexibility and toughness that confers mechanical resilience to the cell. Vimentin is an IF protein expressed in mesenchymal cells. This review highlights exciting new results on the physical biology of vimentin intermediate filaments and their role in allowing whole cells and tissues to cope with stress.
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Affiliation(s)
- Alison E Patteson
- Physics Department, Syracuse University, Syracuse, NY 13244, USA
- BioInspired Institute, Syracuse University, Syracuse, NY 13244, USA
| | - Robert J Carroll
- Physics Department, Syracuse University, Syracuse, NY 13244, USA
- BioInspired Institute, Syracuse University, Syracuse, NY 13244, USA
| | - Daniel V Iwamoto
- Institute for Medicine and Engineering, Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Paul A Janmey
- Institute for Medicine and Engineering, Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
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9
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Schepers AV, Lorenz C, Köster S. Tuning intermediate filament mechanics by variation of pH and ion charges. NANOSCALE 2020; 12:15236-15245. [PMID: 32642745 DOI: 10.1039/d0nr02778b] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The cytoskeleton is formed by three types of filamentous proteins - microtubules, actin filaments, and intermediate filaments (IFs) - and enables cells to withstand external and internal forces. Vimentin is the most abundant IF protein in humans and assembles into 10 nm diameter filaments with remarkable mechanical properties, such as high extensibility and stability. It is, however, unclear to which extent these properties are influenced by the electrostatic environment. Here, we study the mechanical properties of single vimentin filaments by employing optical trapping combined with microfluidics. Force-strain curves, recorded at varying ion concentrations and pH values, reveal that the mechanical properties of single vimentin IFs are influenced by pH and ion concentration. By combination with Monte Carlo simulations, we relate these altered mechanics to electrostatic interactions of subunits within the filaments. We thus suggest possible mechanisms that allow cells to locally tune their stiffness without remodeling the entire cytoskeleton.
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Affiliation(s)
- Anna V Schepers
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
| | - Charlotta Lorenz
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
| | - Sarah Köster
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
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10
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Haimov E, Windoffer R, Leube RE, Urbakh M, Kozlov MM. Model for Bundling of Keratin Intermediate Filaments. Biophys J 2020; 119:65-74. [PMID: 32533940 PMCID: PMC7335914 DOI: 10.1016/j.bpj.2020.05.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 05/19/2020] [Accepted: 05/20/2020] [Indexed: 01/19/2023] Open
Abstract
Keratin intermediate filaments form dynamic intracellular networks, which span the entire cytoplasm and provide mechanical strength to the cell. The mechanical resilience of the keratin intermediate filament network itself is determined by filament bundling. The bundling process can be reproduced in artificial conditions in the absence of any specific cross-linking proteins, which suggests that it is driven by generic physical forces acting between filaments. Here, we suggest a detailed model for bundling of keratin intermediate filaments based on interfilament electrostatic and hydrophobic interactions. It predicts that the process is limited by an optimal bundle thickness, which is determined by the electric charge of the filaments, the number of hydrophobic residues in the constituent keratin polypeptides, and the extent to which the electrolyte ions are excluded from the bundle interior. We evaluate the kinetics of the bundling process by considering the energy barrier a filament has to overcome for joining a bundle.
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Affiliation(s)
- Ehud Haimov
- School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Reinhard Windoffer
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Aachen, Germany
| | - Rudolf E Leube
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Aachen, Germany
| | - Michael Urbakh
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel-Aviv University, Tel-Aviv, Israel.
| | - Michael M Kozlov
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
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11
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Wu H, Shen Y, Wang D, Herrmann H, Goldman RD, Weitz DA. Effect of Divalent Cations on the Structure and Mechanics of Vimentin Intermediate Filaments. Biophys J 2020; 119:55-64. [PMID: 32521238 DOI: 10.1016/j.bpj.2020.05.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 05/11/2020] [Accepted: 05/13/2020] [Indexed: 12/30/2022] Open
Abstract
Divalent cations behave as effective cross-linkers of intermediate filaments (IFs) such as vimentin IF (VIF). These interactions have been mostly attributed to their multivalency. However, ion-protein interactions often depend on the ion species, and these effects have not been widely studied in IFs. Here, we investigate the effects of two biologically important divalent cations, Zn2+ and Ca2+, on VIF network structure and mechanics in vitro. We find that the network structure is unperturbed at micromolar Zn2+ concentrations, but strong bundle formation is observed at a concentration of 100 μM. Microrheological measurements show that network stiffness increases with cation concentration. However, bundling of filaments softens the network. This trend also holds for VIF networks formed in the presence of Ca2+, but remarkably, a concentration of Ca2+ that is two orders higher is needed to achieve the same effect as with Zn2+, which suggests the importance of salt-protein interactions as described by the Hofmeister effect. Furthermore, we find evidence of competitive binding between the two divalent ion species. Hence, specific interactions between VIFs and divalent cations are likely to be an important mechanism by which cells can control their cytoplasmic mechanics.
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Affiliation(s)
- Huayin Wu
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts
| | - Yinan Shen
- Department of Physics, Harvard University, Cambridge, Massachusetts
| | - Dianzhuo Wang
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts; Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Harald Herrmann
- Division of Cell Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany; Institute of Neuropathology, University Hospital Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Robert D Goldman
- Department of Cell and Developmental Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - David A Weitz
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts; Department of Physics, Harvard University, Cambridge, Massachusetts.
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12
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Mónico A, Zorrilla S, Rivas G, Pérez-Sala D. Zinc Differentially Modulates the Assembly of Soluble and Polymerized Vimentin. Int J Mol Sci 2020; 21:E2426. [PMID: 32244501 PMCID: PMC7177742 DOI: 10.3390/ijms21072426] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Revised: 03/27/2020] [Accepted: 03/30/2020] [Indexed: 01/12/2023] Open
Abstract
The intermediate filament protein vimentin constitutes a critical sensor for electrophilic and oxidative stress. We previously showed that vimentin interacts with zinc, which affects its assembly and redox sensing. Here, we used vimentin wt and C328S, an oxidation-resistant mutant showing improved NaCl-induced polymerization, to assess the impact of zinc on soluble and polymerized vimentin by light scattering and electron microscopy. Zinc acts as a switch, reversibly inducing the formation of vimentin oligomeric species. High zinc concentrations elicit optically-detectable vimentin structures with a characteristic morphology depending on the support. These effects also occur in vimentin C328S, but are not mimicked by magnesium. Treatment of vimentin with micromolar ZnCl2 induces fibril-like particles that do not assemble into filaments, but form aggregates upon subsequent addition of NaCl. In contrast, when added to NaCl-polymerized vimentin, zinc increases the diameter or induces lateral association of vimentin wt filaments. Remarkably, these effects are absent or attenuated in vimentin C328S filaments. Therefore, the zinc-vimentin interaction depends on the chemical environment and on the assembly state of the protein, leading to atypical polymerization of soluble vimentin, likely through electrostatic interactions, or to broadening and lateral association of preformed filaments through mechanisms requiring the cysteine residue. Thus, the impact of zinc on vimentin assembly and redox regulation is envisaged.
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Affiliation(s)
| | | | | | - Dolores Pérez-Sala
- Department of Structural and Chemical Biology, Centro de Investigaciones Biológicas Margarita Salas, Ramiro de Maeztu, 9, 28040 Madrid, Spain; (A.M.); (S.Z.); (G.R.)
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13
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Zorrilla S, Mónico A, Duarte S, Rivas G, Pérez-Sala D, Pajares MA. Integrated approaches to unravel the impact of protein lipoxidation on macromolecular interactions. Free Radic Biol Med 2019; 144:203-217. [PMID: 30991143 DOI: 10.1016/j.freeradbiomed.2019.04.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 04/03/2019] [Accepted: 04/10/2019] [Indexed: 12/13/2022]
Abstract
Protein modification by lipid derived reactive species, or lipoxidation, is increased during oxidative stress, a common feature observed in many pathological conditions. Biochemical and functional consequences of lipoxidation include changes in the conformation and assembly of the target proteins, altered recognition of ligands and/or cofactors, changes in the interactions with DNA or in protein-protein interactions, modifications in membrane partitioning and binding and/or subcellular localization. These changes may impact, directly or indirectly, signaling pathways involved in the activation of cell defense mechanisms, but when these are overwhelmed they may lead to pathological outcomes. Mass spectrometry provides state of the art approaches for the identification and characterization of lipoxidized proteins/residues and the modifying species. Nevertheless, understanding the complexity of the functional effects of protein lipoxidation requires the use of additional methodologies. Herein, biochemical and biophysical methods used to detect and measure functional effects of protein lipoxidation at different levels of complexity, from in vitro and reconstituted cell-like systems to cells, are reviewed, focusing especially on macromolecular interactions. Knowledge generated through innovative and complementary technologies will contribute to comprehend the role of lipoxidation in pathophysiology and, ultimately, its potential as target for therapeutic intervention.
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Affiliation(s)
- Silvia Zorrilla
- Dept. of Structural and Chemical Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040, Madrid, Spain.
| | - Andreia Mónico
- Dept. of Structural and Chemical Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Sofia Duarte
- Dept. of Structural and Chemical Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Germán Rivas
- Dept. of Structural and Chemical Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Dolores Pérez-Sala
- Dept. of Structural and Chemical Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - María A Pajares
- Dept. of Structural and Chemical Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040, Madrid, Spain.
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14
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Miyasaka Y, Murakami K, Ito K, Kumaki J, Makabe K, Hatori K. Condensed desmin and actin cytoskeletal communication in lipid droplets. Cytoskeleton (Hoboken) 2019; 76:477-490. [DOI: 10.1002/cm.21573] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 10/14/2019] [Accepted: 10/15/2019] [Indexed: 12/23/2022]
Affiliation(s)
- Yoshiya Miyasaka
- Department of Bio‐Systems Engineering, Graduate School of Science and EngineeringYamagata University Yamagata Japan
| | - Keigo Murakami
- Department of Bio‐Systems Engineering, Graduate School of Science and EngineeringYamagata University Yamagata Japan
| | - Koji Ito
- Department of Bio‐Systems Engineering, Graduate School of Science and EngineeringYamagata University Yamagata Japan
| | - Jiro Kumaki
- Department of Organic Materials Science, Graduate School of Organic Materials ScienceYamagata University Yamagata Japan
| | - Koki Makabe
- Department of Biochemical Engineering, Graduate School of Science and EngineeringYamagata University Yamagata Japan
| | - Kuniyuki Hatori
- Department of Bio‐Systems Engineering, Graduate School of Science and EngineeringYamagata University Yamagata Japan
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15
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Lorenz C, Forsting J, Schepers AV, Kraxner J, Bauch S, Witt H, Klumpp S, Köster S. Lateral Subunit Coupling Determines Intermediate Filament Mechanics. PHYSICAL REVIEW LETTERS 2019; 123:188102. [PMID: 31763918 DOI: 10.1103/physrevlett.123.188102] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Indexed: 05/27/2023]
Abstract
The cytoskeleton is a composite network of three types of protein filaments, among which intermediate filaments (IFs) are the most extensible ones. Two very important IFs are keratin and vimentin, which have similar molecular architectures but different mechanical behaviors. Here we compare the mechanical response of single keratin and vimentin filaments using optical tweezers. We show that the mechanics of vimentin strongly depends on the ionic strength of the buffer and that its force-strain curve suggests a high degree of cooperativity between subunits. Indeed, a computational model indicates that in contrast to keratin, vimentin is characterized by strong lateral subunit coupling of its charged monomers during unfolding of α helices. We conclude that cells can tune their mechanics by differential use of keratin versus vimentin.
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Affiliation(s)
- Charlotta Lorenz
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Johanna Forsting
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Anna V Schepers
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Julia Kraxner
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Susanne Bauch
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Hannes Witt
- Institute for Organic and Biomolecular Chemistry, University of Göttingen, Tammanstraße 2, 37077 Göttingen, Germany
- Max Planck Institute for Dynamics and Self-Organization, Am Faßberg 7, 37077 Göttingen
| | - Stefan Klumpp
- Institute for Dynamics of Complex Systems, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Sarah Köster
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
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16
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Brennich ME, Vainio U, Wedig T, Bauch S, Herrmann H, Köster S. Mutation-induced alterations of intra-filament subunit organization in vimentin filaments revealed by SAXS. SOFT MATTER 2019; 15:1999-2008. [PMID: 30719518 DOI: 10.1039/c8sm02281j] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Vimentin intermediate filaments constitute a distinct filament system in mesenchymal cells that is instrumental for cellular mechanics and migration. In vitro, the rod-like monomers assemble in a multi-step, salt-dependent manner into micrometer long biopolymers. To disclose the underlying mechanisms further, we employed small angle X-ray scattering on two recombinant vimentin variants, whose assembly departs at strategic points from the normal assembly route: (i) vimentin with a tyrosine to leucine change at position 117; (ii) vimentin missing the non-α-helical carboxyl-terminal domain. Y117L vimentin assembles into unit-length filaments (ULFs) only, whereas ΔT vimentin assembles into filaments containing a higher number of tetramers per cross section than normal vimentin filaments. We show that the shape and inner structure of these mutant filaments is significantly altered. ULFs assembled from Y117L vimentin contain more, less tightly bundled vimentin tetramers, and ΔT vimentin filaments preserve the number density despite the higher number of tetramers per filament cross-section.
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Affiliation(s)
- Martha E Brennich
- Institute for X-ray Physics, University of Goettingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
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17
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Rambach RW, Biswas P, Yadav A, Garstecki P, Franke T. Fast selective trapping and release of picoliter droplets in a 3D microfluidic PDMS multi-trap system with bubbles. Analyst 2018; 143:843-849. [PMID: 29234760 DOI: 10.1039/c7an01100h] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The selective manipulation and incubation of individual picoliter drops in high-throughput droplet based microfluidic devices still remains challenging. We used a surface acoustic wave (SAW) to induce a bubble in a 3D designed multi-trap polydimethylsiloxane (PDMS) device to manipulate multiple droplets and demonstrate the selection, incubation and on-demand release of aqueous droplets from a continuous oil flow. By controlling the position of the acoustic actuation, individual droplets are addressed and selectively released from a droplet stream of 460 drops per s. A complete trapping and releasing cycle can be as short as 70 ms and has no upper limit for incubation time. We characterize the fluidic function of the hybrid device in terms of electric power, pulse duration and acoustic path.
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Affiliation(s)
- Richard W Rambach
- Soft Matter and Biological Physics Group, Universität Augsburg, Universitätsstr. 1, D-86159 Augsburg, Germany
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18
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Rambach RW, Linder K, Heymann M, Franke T. Droplet trapping and fast acoustic release in a multi-height device with steady-state flow. LAB ON A CHIP 2017; 17:3422-3430. [PMID: 28792054 DOI: 10.1039/c7lc00378a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We demonstrate a novel multilayer polydimethylsiloxane (PDMS) device for selective storage and release of single emulsion droplets. Drops are captured in a microchannel cavity and can be released on-demand through a triggered surface acoustic wave pulse. The surface acoustic wave (SAW) is excited by a tapered interdigital transducer (TIDT) deposited on a piezoelectric lithium niobate (LiNbO3) substrate and inverts the pressure difference across the cavity trap to push a drop out of the trap and back into the main flow channel. Droplet capture and release does not require a flow rate change, flow interruption, flow inversion or valve action and can be achieved in as fast as 20 ms. This allows both on-demand droplet capture for analysis and monitoring over arbitrary time scales, and continuous device operation with a high droplet rate of 620 drops per s. We hence decouple long-term droplet interrogation from other operations on the chip. This will ease integration with other microfluidic droplet operations and functional components.
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Affiliation(s)
- Richard W Rambach
- Soft Matter and Biological Physics Group, Universität Augsburg, Universitätsstr. 1, D-86159 Augsburg, Germany
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19
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Saldanha O, Graceffa R, Hémonnot CYJ, Ranke C, Brehm G, Liebi M, Marmiroli B, Weinhausen B, Burghammer M, Köster S. Rapid Acquisition of X-Ray Scattering Data from Droplet-Encapsulated Protein Systems. Chemphyschem 2017; 18:1220-1223. [DOI: 10.1002/cphc.201700221] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Indexed: 11/07/2022]
Affiliation(s)
- Oliva Saldanha
- Institute for X-ray Physics; Georg-August-University Göttingen; 37077 Göttingen Germany
| | - Rita Graceffa
- Institute for X-ray Physics; Georg-August-University Göttingen; 37077 Göttingen Germany
- Current address: European XFEL GmbH; 22869 Schenefeld Germany
| | | | - Christiane Ranke
- Institute for X-ray Physics; Georg-August-University Göttingen; 37077 Göttingen Germany
| | - Gerrit Brehm
- Institute for X-ray Physics; Georg-August-University Göttingen; 37077 Göttingen Germany
| | - Marianne Liebi
- Paul Scherrer Institute; 5232 Villigen Switzerland
- Current address: MAX IV Laboratory; Lund University; 221-00 Lund Sweden
| | - Benedetta Marmiroli
- Institute of Inorganic Chemistry; Graz University of Technology; 8010 Graz Austria
| | - Britta Weinhausen
- European Synchrotron Radiation Facility; 38000 Grenoble France
- Current address: European XFEL GmbH; 22869 Schenefeld Germany
| | - Manfred Burghammer
- European Synchrotron Radiation Facility; 38000 Grenoble France
- Department of Analytical Chemistry; Ghent University; 9000 Ghent Belgium
| | - Sarah Köster
- Institute for X-ray Physics; Georg-August-University Göttingen; 37077 Göttingen Germany
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20
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Mónico A, Martínez-Senra E, Cañada FJ, Zorrilla S, Pérez-Sala D. Drawbacks of Dialysis Procedures for Removal of EDTA. PLoS One 2017; 12:e0169843. [PMID: 28099451 PMCID: PMC5242421 DOI: 10.1371/journal.pone.0169843] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 12/23/2016] [Indexed: 11/18/2022] Open
Abstract
Ethylenediaminetetraacetic acid (EDTA) is a chelating agent commonly used in protein purification, both to eliminate contaminating divalent cations and to inhibit protease activity. For a number of subsequent applications EDTA needs to be exhaustively removed. Most purification methods rely in extensive dialysis and/or gel filtration in order to exchange or remove protein buffer components, including metal chelators. We report here that dialysis protocols, even as extensive as those typically employed for protein refolding, may not effectively remove EDTA, which is reduced only by approximately two-fold and it also persists after spin-column gel filtration, as determined by NMR and by colorimetric methods. Remarkably, the most efficient removal was achieved by ultrafiltration, after which EDTA became virtually undetectable. These results highlight a potentially widespread source of experimental variability affecting free divalent cation concentrations in protein applications.
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Affiliation(s)
- Andreia Mónico
- Department of Chemical and Physical Biology, Centro de Investigaciones Biológicas, C.S.I.C., Madrid, Spain
| | - Eva Martínez-Senra
- Department of Chemical and Physical Biology, Centro de Investigaciones Biológicas, C.S.I.C., Madrid, Spain
| | - F. Javier Cañada
- Department of Chemical and Physical Biology, Centro de Investigaciones Biológicas, C.S.I.C., Madrid, Spain
| | - Silvia Zorrilla
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, C.S.I.C., Madrid, Spain
| | - Dolores Pérez-Sala
- Department of Chemical and Physical Biology, Centro de Investigaciones Biológicas, C.S.I.C., Madrid, Spain
- * E-mail:
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21
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Seiffert S. Microfluidics and Macromolecules: Top-Down Analytics and Bottom-Up Engineering of Soft Matter at Small Scales. MACROMOL CHEM PHYS 2016. [DOI: 10.1002/macp.201600280] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Sebastian Seiffert
- Johannes Gutenberg-Universität Mainz; Institute of Physical Chemistry; Duesbergweg 10-14 55128 Mainz Germany
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22
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Saldanha O, Brennich ME, Burghammer M, Herrmann H, Köster S. The filament forming reactions of vimentin tetramers studied in a serial-inlet microflow device by small angle x-ray scattering. BIOMICROFLUIDICS 2016; 10:024108. [PMID: 27042250 PMCID: PMC4798992 DOI: 10.1063/1.4943916] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 03/02/2016] [Indexed: 05/16/2023]
Abstract
The structural organization of metazoan cells and their shape are established through the coordinated interaction of a composite network consisting of three individual filament systems, collectively termed the cytoskeleton. Specifically, microtubules and actin filaments, which assemble from monomeric globular proteins, provide polar structures that serve motor proteins as tracks. In contrast, intermediate filaments (IFs) assemble from highly charged, extended coiled coils in a hierarchical assembly mechanism of lateral and longitudinal interaction steps into non-polar structures. IF proteins are expressed in a distinctly tissue-specific way and thereby serve to generate the precise plasticity of the respective cells and tissues. Accordingly, in the cell, numerous parameters such as pH and salt concentration are adjusted such that the generation of functional networks is ensured. Here, we transfer the problem for the mesenchymal IF protein vimentin to an in vitro setting and combine small angle x-ray scattering with microfluidics and finite element method simulations. Our approach is adapted to resolve the early assembly steps, which take place in the sub-second to second range. In particular, we reveal the influence of ion species and concentrations on the assembly. By tuning the flow rates and thus concentration profiles, we find a minimal critical salt concentration for the initiation of the assembly. Furthermore, our analysis of the surface sensitive Porod regime in the x-ray data reveals that the formation of first assembly intermediates, so-called unit length filaments, is not a one-step reaction but consists of distinct consecutive lateral association steps followed by radial compaction as well as smoothening of the surface of the full-width filament.
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Affiliation(s)
- Oliva Saldanha
- Institute for X-Ray Physics, Georg-August-Universität Göttingen , 37077 Göttingen, Germany
| | - Martha E Brennich
- Institute for X-Ray Physics, Georg-August-Universität Göttingen , 37077 Göttingen, Germany
| | | | | | - Sarah Köster
- Institute for X-Ray Physics, Georg-August-Universität Göttingen , 37077 Göttingen, Germany
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23
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Hémonnot CYJ, Mauermann M, Herrmann H, Köster S. Assembly of Simple Epithelial Keratin Filaments: Deciphering the Ion Dependence in Filament Organization. Biomacromolecules 2015; 16:3313-21. [PMID: 26327161 DOI: 10.1021/acs.biomac.5b00965] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The intermediate filament proteins keratin K8 and K18 constitute an essential part of the cytoskeleton in simple epithelial cell layers, structurally enforcing their mechanical resistance. K8/K18 heterodimers form extended filaments and higher-order structures including bundles and networks that bind to cell junctions. We study the assembly of these proteins in the presence of monovalent or divalent ions by small-angle X-ray scattering. We find that both ion species cause an increase of the filament diameter when their concentration is increased; albeit, much higher values are needed for the monovalent compared to the divalent ions for the same effect. Bundling occurs also for monovalent ions and at comparatively low concentrations of divalent ions, very different from vimentin intermediate filaments, a fibroblast-specific cytoskeleton component. We explain these differences by variations in charge and hydrophobicity patterns of the proteins. These differences may reflect the respective physiological situation in stationary cell layers versus single migrating fibroblasts.
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Affiliation(s)
- Clément Y J Hémonnot
- Institute for X-ray Physics, University of Göttingen , Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Monika Mauermann
- Division of Molecular Genetics, German Cancer Research Center , Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Harald Herrmann
- Division of Molecular Genetics, German Cancer Research Center , Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Sarah Köster
- Institute for X-ray Physics, University of Göttingen , Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
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24
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Order and disorder in intermediate filament proteins. FEBS Lett 2015; 589:2464-76. [PMID: 26231765 DOI: 10.1016/j.febslet.2015.07.024] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 07/21/2015] [Accepted: 07/22/2015] [Indexed: 11/20/2022]
Abstract
Intermediate filaments (IFs), important components of the cytoskeleton, provide a versatile, tunable network of self-assembled proteins. IF proteins contain three distinct domains: an α-helical structured rod domain, flanked by intrinsically disordered head and tail domains. Recent studies demonstrated the functional importance of the disordered domains, which differ in length and amino-acid sequence among the 70 different human IF genes. Here, we investigate the biophysical properties of the disordered domains, and review recent findings on the interactions between them. Our analysis highlights key components governing IF functional roles in the cytoskeleton, where the intrinsically disordered domains dictate protein-protein interactions, supramolecular assembly, and macro-scale order.
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25
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Block J, Schroeder V, Pawelzyk P, Willenbacher N, Köster S. Physical properties of cytoplasmic intermediate filaments. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:3053-64. [PMID: 25975455 DOI: 10.1016/j.bbamcr.2015.05.009] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 04/28/2015] [Accepted: 05/05/2015] [Indexed: 11/29/2022]
Abstract
Intermediate filaments (IFs) constitute a sophisticated filament system in the cytoplasm of eukaryotes. They form bundles and networks with adapted viscoelastic properties and are strongly interconnected with the other filament types, microfilaments and microtubules. IFs are cell type specific and apart from biochemical functions, they act as mechanical entities to provide stability and resilience to cells and tissues. We review the physical properties of these abundant structural proteins including both in vitro studies and cell experiments. IFs are hierarchical structures and their physical properties seem to a large part be encoded in the very specific architecture of the biopolymers. Thus, we begin our review by presenting the assembly mechanism, followed by the mechanical properties of individual filaments, network and structure formation due to electrostatic interactions, and eventually the mechanics of in vitro and cellular networks. This article is part of a Special Issue entitled: Mechanobiology.
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Affiliation(s)
- Johanna Block
- Institut für Röntgenphysik, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Viktor Schroeder
- Institut für Röntgenphysik, Georg-August-Universität Göttingen, Göttingen, Germany; Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Göttingen, Germany
| | - Paul Pawelzyk
- Institute of Mechanical Process Engineering and Mechanics, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Norbert Willenbacher
- Institute of Mechanical Process Engineering and Mechanics, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Sarah Köster
- Institut für Röntgenphysik, Georg-August-Universität Göttingen, Göttingen, Germany; Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Göttingen, Germany.
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26
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Dammann C, Herrmann H, Köster S. Competitive Counterion Binding Regulates the Aggregation Onset of Vimentin Intermediate Filaments. Isr J Chem 2015. [DOI: 10.1002/ijch.201400153] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Christian Dammann
- Institute for X-Ray Physics; University of Göttingen; Friedrich-Hund-Platz 1 D-37077 Göttingen Germany
| | - Harald Herrmann
- B065 Functional Architecture of the Cell; German Cancer Research Center (DKFZ); D-69120 Heidelberg Germany)
| | - Sarah Köster
- Institute for X-Ray Physics; University of Göttingen; Friedrich-Hund-Platz 1 D-37077 Göttingen Germany
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27
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Intermediate filament mechanics in vitro and in the cell: from coiled coils to filaments, fibers and networks. Curr Opin Cell Biol 2015; 32:82-91. [PMID: 25621895 DOI: 10.1016/j.ceb.2015.01.001] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 01/05/2015] [Accepted: 01/06/2015] [Indexed: 01/19/2023]
Abstract
Intermediate filament proteins form filaments, fibers and networks both in the cytoplasm and the nucleus of metazoan cells. Their general structural building plan accommodates highly varying amino acid sequences to yield extended dimeric α-helical coiled coils of highly conserved design. These 'rod' particles are the basic building blocks of intrinsically flexible, filamentous structures that are able to resist high mechanical stresses, that is, bending and stretching to a considerable degree, both in vitro and in the cell. Biophysical and computer modeling studies are beginning to unfold detailed structural and mechanical insights into these major supramolecular assemblies of cell architecture, not only in the 'test tube' but also in the cellular and tissue context.
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