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Nefedova VV, Kleymenov SY, Safenkova IV, Levitsky DI, Matyushenko AM. Neurofilament Light Protein Rod Domain Exhibits Structural Heterogeneity. Biomolecules 2024; 14:85. [PMID: 38254685 PMCID: PMC10813002 DOI: 10.3390/biom14010085] [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: 11/06/2023] [Revised: 12/23/2023] [Accepted: 01/06/2024] [Indexed: 01/24/2024] Open
Abstract
Neurofilaments are neuron-specific proteins that belong to the intermediate filament (IFs) protein family, with the neurofilament light chain protein (NFL) being the most abundant. The IFs structure typically includes a central coiled-coil rod domain comprised of coils 1A, 1B, and 2, separated by linker regions. The thermal stability of the IF molecule plays a crucial role in its ability for self-association. In the current study, we investigated the thermal stability of NFL coiled-coil domains by analyzing a set of recombinant domains and their fusions (NFL1B, NFL1A+1B, NFL2, NFL1B+2, and NFLROD) via circular dichroism spectroscopy and differential scanning calorimetry. The thermal stability of coiled-coil domains is evident in a wide range of temperatures, and thermal transition values (Tm) correspond well between isolated coiled-coil domains and full-length NFL. NFL1B has a Tm of 39.4 °C, and its' fusions, NFL1A+1B and NFL1B+2, have a Tm of 41.9 °C and 41.5 °C, respectively. However, in the case of NFL2, thermal denaturation includes at least two thermal transitions at 37.2 °C and 62.7 °C. These data indicate that the continuous α-helical structure of the coil 2 domain has parts with varied thermal stability. Among all the NFL fragments, only NFL2 underwent irreversible heat-induced denaturation. Together, these results unveil the origin of full-length NFL's thermal transitions, and reveal its domains structure and properties.
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Affiliation(s)
- Victoria V. Nefedova
- Research Centre of Biotechnology, Russian Academy of Sciences, 119071 Moscow, Russia; (S.Y.K.); (I.V.S.); (D.I.L.); (A.M.M.)
| | - Sergey Y. Kleymenov
- Research Centre of Biotechnology, Russian Academy of Sciences, 119071 Moscow, Russia; (S.Y.K.); (I.V.S.); (D.I.L.); (A.M.M.)
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, 119334 Moscow, Russia
| | - Irina V. Safenkova
- Research Centre of Biotechnology, Russian Academy of Sciences, 119071 Moscow, Russia; (S.Y.K.); (I.V.S.); (D.I.L.); (A.M.M.)
| | - Dmitrii I. Levitsky
- Research Centre of Biotechnology, Russian Academy of Sciences, 119071 Moscow, Russia; (S.Y.K.); (I.V.S.); (D.I.L.); (A.M.M.)
| | - Alexander M. Matyushenko
- Research Centre of Biotechnology, Russian Academy of Sciences, 119071 Moscow, Russia; (S.Y.K.); (I.V.S.); (D.I.L.); (A.M.M.)
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2
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Uchida A, Peng J, Brown A. Regulation of neurofilament length and transport by a dynamic cycle of phospho-dependent polymer severing and annealing. Mol Biol Cell 2023; 34:ar68. [PMID: 36989035 PMCID: PMC10295484 DOI: 10.1091/mbc.e23-01-0024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 03/17/2023] [Accepted: 03/22/2023] [Indexed: 03/30/2023] Open
Abstract
Neurofilaments are cargoes of axonal transport which are unique among known intracellular cargoes in that they are long, flexible protein polymers. These polymers are transported into axons, where they accumulate in large numbers to drive the expansion of axon caliber, which is an important determinant of axonal conduction velocity. We reported previously that neurofilaments can be lengthened by joining ends, called end-to-end annealing, and that they can be shortened by severing. Here, we show that neurofilament annealing and severing are robust and quantifiable phenomena in cultured neurons that act antagonistically to regulate neurofilament length. We show that this in turn regulates neurofilament transport and that severing is regulated by N-terminal phosphorylation of the neurofilament subunit proteins. We propose that focal destabilization of intermediate filaments by site-directed phosphorylation may be a general enzymatic mechanism for severing these cytoskeletal polymers, providing a mechanism to regulate the transport and accumulation of neurofilaments in axons.
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Affiliation(s)
- Atsuko Uchida
- Department of Neuroscience, Ohio State University, Columbus, OH 43210
| | - Juan Peng
- Center for Biostatistics and Department of Biomedical Informatics, Ohio State University, Columbus, OH 43210
| | - Anthony Brown
- Department of Neuroscience, Ohio State University, Columbus, OH 43210
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3
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Nefedova VV, Yampolskaya DS, Kleymenov SY, Chebotareva NA, Matyushenko AM, Levitsky DI. Effect of Neurodegenerative Mutations in the NEFL Gene on Thermal Denaturation of the Neurofilament Light Chain Protein. BIOCHEMISTRY. BIOKHIMIIA 2023; 88:610-620. [PMID: 37331707 DOI: 10.1134/s0006297923050048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 03/02/2023] [Accepted: 03/02/2023] [Indexed: 06/20/2023]
Abstract
Effects of E90K, N98S, and A149V mutations in the light chain of neurofilaments (NFL) on the structure and thermal denaturation of the NFL molecule were investigated. By using circular dichroism spectroscopy, it was shown that these mutations did not lead to the changes in α-helical structure of NFL, but they caused noticeable effects on the stability of the molecule. We also identified calorimetric domains in the NFL structure by using differential scanning calorimetry. It was shown that the E90K replacement leads to the disappearance of the low-temperature thermal transition (domain 1). The mutations cause changes in the enthalpy of NFL domains melting, as well as lead to the significant changes in the melting temperatures (Tm) of some calorimetric domains. Thus, despite the fact that all these mutations are associated with the development of Charcot-Marie-Tooth neuropathy, and two of them are even located very close to each other in the coil 1A, they affect differently structure and stability of the NFL molecule.
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Affiliation(s)
- Victoria V Nefedova
- Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia.
| | - Daria S Yampolskaya
- Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia
| | - Sergey Y Kleymenov
- Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, Moscow, 119334, Russia
| | - Natalia A Chebotareva
- Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia
| | | | - Dmitrii I Levitsky
- Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia
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4
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Fluorescence microscopic imaging of single desmin intermediate filaments elongated by the presence of divalent cations in vitro. Biophys Chem 2022; 287:106839. [DOI: 10.1016/j.bpc.2022.106839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 04/27/2022] [Accepted: 05/24/2022] [Indexed: 11/18/2022]
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5
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Kaus‐Drobek M, Mücke N, Szczepanowski RH, Wedig T, Czarnocki‐Cieciura M, Polakowska M, Herrmann H, Wysłouch‐Cieszyńska A, Dadlez M. Vimentin S-glutathionylation at Cys328 inhibits filament elongation and induces severing of mature filaments in vitro. FEBS J 2020; 287:5304-5322. [PMID: 32255262 PMCID: PMC7818121 DOI: 10.1111/febs.15321] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 02/17/2020] [Accepted: 03/31/2020] [Indexed: 12/26/2022]
Abstract
Vimentin intermediate filaments are a significant component of the cytoskeleton in cells of mesenchymal origin. In vivo, filaments assemble and disassemble and thus participate in the dynamic processes of the cell. Post-translational modifications (PTMs) such as protein phosphorylation regulate the multiphasic association of vimentin from soluble complexes to insoluble filaments and the reverse processes. The thiol side chain of the single vimentin cysteine at position 328 (Cys328) is a direct target of oxidative modifications inside cells. Here, we used atomic force microscopy, electron microscopy and a novel hydrogen-deuterium exchange mass spectrometry (HDex-MS) procedure to investigate the structural consequences of S-nitrosylation and S-glutathionylation of Cys328 for in vitro oligomerisation of human vimentin. Neither modification affects the lateral association of tetramers to unit-length filaments (ULF). However, S-glutathionylation of Cys328 blocks the longitudinal assembly of ULF into extended filaments. S-nitrosylation of Cys328 does not hinder but slows down the elongation. Likewise, S-glutathionylation of preformed vimentin filaments causes their extensive fragmentation to smaller oligomeric species. Chemical reduction of the S-glutathionylated Cys328 thiols induces reassembly of the small fragments into extended filaments. In conclusion, our in vitro results suggest S-glutathionylation as a candidate PTM for an efficient molecular switch in the dynamic rearrangements of vimentin intermediate filaments, observed in vivo, in response to changes in cellular redox status. Finally, we demonstrate that HDex-MS is a powerful method for probing the kinetics of vimentin filament formation and filament disassembly induced by PTMs.
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Affiliation(s)
- Magdalena Kaus‐Drobek
- Laboratory of Mass SpectrometryInstitute of Biochemistry and BiophysicsPolish Academy of SciencesWarsawPoland
| | - Norbert Mücke
- Biophysics of MacromoleculesGerman Cancer Research Center (DKFZ)HeidelbergGermany
- Chromatin NetworksGerman Cancer Research Center (DKFZ)HeidelbergGermany
| | - Roman H. Szczepanowski
- Biophysics Core FacilityInternational Institute of Molecular and Cell BiologyWarsawPoland
| | - Tatjana Wedig
- Biophysics of MacromoleculesGerman Cancer Research Center (DKFZ)HeidelbergGermany
| | | | - Magdalena Polakowska
- Laboratory of Mass SpectrometryInstitute of Biochemistry and BiophysicsPolish Academy of SciencesWarsawPoland
| | - Harald Herrmann
- Institute of NeuropathologyUniversity Hospital ErlangenGermany
- Division of Molecular GeneticsGerman Cancer Research Center (DKFZ)HeidelbergGermany
| | | | - Michał Dadlez
- Laboratory of Mass SpectrometryInstitute of Biochemistry and BiophysicsPolish Academy of SciencesWarsawPoland
- Biology DepartmentInstitute of Genetics and BiotechnologyWarsaw UniversityPoland
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6
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Herrmann H, Cabet E, Chevalier NR, Moosmann J, Schultheis D, Haas J, Schowalter M, Berwanger C, Weyerer V, Agaimy A, Meder B, Müller OJ, Katus HA, Schlötzer-Schrehardt U, Vicart P, Ferreiro A, Dittrich S, Clemen CS, Lilienbaum A, Schröder R. Dual Functional States of R406W-Desmin Assembly Complexes Cause Cardiomyopathy With Severe Intercalated Disc Derangement in Humans and in Knock-In Mice. Circulation 2020; 142:2155-2171. [PMID: 33023321 DOI: 10.1161/circulationaha.120.050218] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Mutations in the human desmin gene cause myopathies and cardiomyopathies. This study aimed to elucidate molecular mechanisms initiated by the heterozygous R406W-desmin mutation in the development of a severe and early-onset cardiac phenotype. METHODS We report an adolescent patient who underwent cardiac transplantation as a result of restrictive cardiomyopathy caused by a heterozygous R406W-desmin mutation. Sections of the explanted heart were analyzed with antibodies specific to 406W-desmin and to intercalated disc proteins. Effects of the R406W mutation on the molecular properties of desmin were addressed by cell transfection and in vitro assembly experiments. To prove the genuine deleterious effect of the mutation on heart tissue, we further generated and analyzed R405W-desmin knock-in mice harboring the orthologous form of the human R406W-desmin. RESULTS Microscopic analysis of the explanted heart revealed desmin aggregates and the absence of desmin filaments at intercalated discs. Structural changes within intercalated discs were revealed by the abnormal organization of desmoplakin, plectin, N-cadherin, and connexin-43. Next-generation sequencing confirmed the DES variant c.1216C>T (p.R406W) as the sole disease-causing mutation. Cell transfection studies disclosed a dual behavior of R406W-desmin with both its integration into the endogenous intermediate filament system and segregation into protein aggregates. In vitro, R406W-desmin formed unusually thick filaments that organized into complex filament aggregates and fibrillar sheets. In contrast, assembly of equimolar mixtures of mutant and wild-type desmin generated chimeric filaments of seemingly normal morphology but with occasional prominent irregularities. Heterozygous and homozygous R405W-desmin knock-in mice develop both a myopathy and a cardiomyopathy. In particular, the main histopathologic results from the patient are recapitulated in the hearts from R405W-desmin knock-in mice of both genotypes. Moreover, whereas heterozygous knock-in mice have a normal life span, homozygous animals die at 3 months of age because of a smooth muscle-related gastrointestinal phenotype. CONCLUSIONS We demonstrate that R406W-desmin provokes its severe cardiotoxic potential by a novel pathomechanism, where the concurrent dual functional states of mutant desmin assembly complexes underlie the uncoupling of desmin filaments from intercalated discs and their structural disorganization.
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Affiliation(s)
- Harald Herrmann
- Institute of Neuropathology (H.H., D.S., M.S., R.S.), University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Germany.,Molecular Genetics, German Cancer Research Center, Heidelberg, Germany (H.H.)
| | - Eva Cabet
- Basic and Translational Myology, Unit of Functional and Adaptive Biology (E.C., P.V., A.F., A.L.), University of Paris, France
| | - Nicolas R Chevalier
- Laboratoire Matière et Systèmes Complexes (N.R.C.), University of Paris, France
| | - Julia Moosmann
- Department of Pediatric Cardiology (J.M., S.D.), University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Germany
| | - Dorothea Schultheis
- Institute of Neuropathology (H.H., D.S., M.S., R.S.), University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Germany
| | - Jan Haas
- Institute for Cardiomyopathies Heidelberg, Heart Center Heidelberg, University of Heidelberg, Germany (J.H., B.M.)
| | - Mirjam Schowalter
- Institute of Neuropathology (H.H., D.S., M.S., R.S.), University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Germany
| | - Carolin Berwanger
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany (C.B., C.S.C.)
| | - Veronika Weyerer
- Institute of Pathology (V.W., A.A.), University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Germany
| | - Abbas Agaimy
- Institute of Pathology (V.W., A.A.), University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Germany
| | - Benjamin Meder
- Institute for Cardiomyopathies Heidelberg, Heart Center Heidelberg, University of Heidelberg, Germany (J.H., B.M.).,Department of Genetics, Stanford University School of Medicine, CA (B.M.)
| | - Oliver J Müller
- Internal Medicine III, University Hospital Schleswig-Holstein and University of Kiel, and German Center for Cardiovascular Research, partner site Hamburg/Kiel/Lübeck, Kiel, Germany (O.J.M.)
| | - Hugo A Katus
- Department of Cardiology, Medical University Hospital Heidelberg, and German Center for Cardiovascular Research, partner site Heidelberg/Mannheim, Heidelberg, Germany (H.A.K.)
| | - Ursula Schlötzer-Schrehardt
- Department of Ophthalmology (U.S.-S.), University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Germany
| | - Patrick Vicart
- Basic and Translational Myology, Unit of Functional and Adaptive Biology (E.C., P.V., A.F., A.L.), University of Paris, France
| | - Ana Ferreiro
- Basic and Translational Myology, Unit of Functional and Adaptive Biology (E.C., P.V., A.F., A.L.), University of Paris, France.,Reference Center for Neuromuscular Disorders, Pitié-Salpêtrière Hospital, Assistance publique-Hôpitaux de Paris, France (A.F.)
| | - Sven Dittrich
- Department of Pediatric Cardiology (J.M., S.D.), University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Germany
| | - Christoph S Clemen
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany (C.B., C.S.C.).,Center for Physiology and Pathophysiology, Institute of Vegetative Physiology, Medical Faculty, and Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, Germany(C.S.C.)
| | - Alain Lilienbaum
- Basic and Translational Myology, Unit of Functional and Adaptive Biology (E.C., P.V., A.F., A.L.), University of Paris, France
| | - Rolf Schröder
- Institute of Neuropathology (H.H., D.S., M.S., R.S.), University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Germany
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7
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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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8
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Aufderhorst-Roberts A, Koenderink GH. Stiffening and inelastic fluidization in vimentin intermediate filament networks. SOFT MATTER 2019; 15:7127-7136. [PMID: 31334536 DOI: 10.1039/c9sm00590k] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Intermediate filaments are cytoskeletal proteins that are key regulators of cell mechanics, a role which is intrinsically tied to their hierarchical structure and their unique ability to accommodate large axial strains. However, how the single-filament response to applied strains translates to networks remains unclear, particularly with regards to the crosslinking role played by the filaments' disordered "tail" domains. Here we test the role of these noncovalent crosslinks in the nonlinear rheology of reconstituted networks of the intermediate filament protein vimentin, probing their stress- and rate-dependent mechanics. Similarly to previous studies we observe elastic stress-stiffening but unlike previous work we identify a characteristic yield stress σ*, above which the networks exhibit rate-dependent softening of the network, referred to as inelastic fluidization. By investigating networks formed from tail-truncated vimentin, in which noncovalent crosslinking is suppressed, and glutaraldehyde-treated vimentin, in which crosslinking is made permanent, we show that rate-dependent inelastic fluidization is a direct consequence of vimentin's transient crosslinking. Surprisingly, although the tail-tail crosslinks are individually weak, the effective timescale for stress relaxation of the network exceeds 1000 s at σ*. Vimentin networks can therefore maintain their integrity over a large range of strains (up to ∼1000%) and loading rates (10-3 to 10-1 s-1). Our results provide insight into how the hierarchical structure of vimentin networks contributes to the cell's ability to be deformable yet strong.
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9
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Structural basis for lamin assembly at the molecular level. Nat Commun 2019; 10:3757. [PMID: 31434876 PMCID: PMC6704074 DOI: 10.1038/s41467-019-11684-x] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 07/26/2019] [Indexed: 12/02/2022] Open
Abstract
Nuclear structure and function are governed by lamins, which are intermediate filaments that mostly consist of α-helices. Different lamin assembly models have been proposed based on low resolution and fragmented structures. However, their assembly mechanisms are still poorly understood at the molecular level. Here, we present the crystal structure of a long human lamin fragment at 3.2 Å resolution that allows the visualization of the features of the full-length protein. The structure shows an anti-parallel arrangement of the two coiled-coil dimers, which is important for the assembly process. We further discover an interaction between the lamin dimers by using chemical cross-linking and mass spectrometry analysis. Based on these two interactions, we propose a molecular mechanism for lamin assembly that is in agreement with a recent model representing the native state and could explain pathological mutations. Our findings also provide the molecular basis for assembly mechanisms of other intermediate filaments. Lamins are intermediate filaments and the major component of the nuclear lamina. Here the authors determine the crystal structure of a construct comprising the N-terminal half of human lamin A/C and use their structure and cross-linking and biochemical experiments to discuss lamin assembly.
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10
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Golde T, Glaser M, Tutmarc C, Elbalasy I, Huster C, Busteros G, Smith DM, Herrmann H, Käs JA, Schnauß J. The role of stickiness in the rheology of semiflexible polymers. SOFT MATTER 2019; 15:4865-4872. [PMID: 31161188 DOI: 10.1039/c9sm00433e] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Semiflexible polymers form central structures in biological material. Modelling approaches usually neglect influences of polymer-specific molecular features aiming to describe semiflexible polymers universally. Here, we investigate the influence of molecular details on networks assembled from filamentous actin, intermediate filaments, and synthetic DNA nanotubes. In contrast to prevalent theoretical assumptions, we find that bulk properties are affected by various inter-filament interactions. We present evidence that these interactions can be merged into a single parameter in the frame of the glassy wormlike chain model. The interpretation of this parameter as a polymer specific stickiness is consistent with observations from macro-rheological measurements and reptation behaviour. Our findings demonstrate that stickiness should generally not be ignored in semiflexible polymer models.
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Affiliation(s)
- Tom Golde
- Peter Debye Institute for Soft Matter Physics, University of Leipzig, 04103 Leipzig, Germany.
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11
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Pietraszkiewicz A, Hampton C, Caplash S, Lei L, Capetanaki Y, Tadvalkar G, Pal-Ghosh S, Stepp MA, Bargagna-Mohan P, Mohan R. Desmin deficiency is not sufficient to prevent corneal fibrosis. Exp Eye Res 2019; 180:155-163. [PMID: 30590024 PMCID: PMC6389382 DOI: 10.1016/j.exer.2018.12.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 11/08/2018] [Accepted: 12/22/2018] [Indexed: 12/16/2022]
Abstract
The type III intermediate filament (IF) proteins vimentin and desmin are sequentially overexpressed in stromal myofibroblasts over the period when fibrosis sets in after corneal injury. Prior findings have revealed vimentin-deficient mice are significantly protected from corneal fibrosis after alkali injury, which has implicated this IF protein as an important regulator of corneal fibrosis. It has remained as yet unproven whether desmin contributes in any significant manner to corneal fibrosis. Here we have employed desmin-deficient (Des KO) mice in the corneal alkali injury model and show that injured Des KO mice develop fibrosis and show similar levels of corneal opacity at 14 days post-injury as wild type (WT) mice and retain this phenotype even at 30d post injury. Des KO corneas from injured mice show upregulation of vimentin and alpha-smooth muscle actin expression to equivalent levels as WT corneas, illuminating that desmin deficiency does not interfere with myofibrobast differentiation. Employing the small molecule withaferin A (WFA), an inhibitor of vimentin, we show that WFA treatment causes the decrease in steady state levels of vimentin and serine 38 phosphorylated vimentin, the latter a biomarker associated with corneal fibrosis, and improved corneal clarity through blockade of myofibroblast differentiation. To investigate further the mechanism of fibrosis in desmin deficiency, we examined keratin 8 expression in the epithelium, and found reduced levels of this cytokeratin in injured Des KO corneas compared to WT corneas. This finding also corroborates the decrease of cell proliferation in injured Des KO corneas compared to that in WT corneas. The fibrotic phenotype of Des KO corneas also features abundant vascularization, further exemplifying the magnitude of corneal pathology. Together, these findings illuminate that desmin does not contribute significantly to corneal fibrosis in this injury model.
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Affiliation(s)
| | - Christopher Hampton
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, USA
| | - Sonny Caplash
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, USA
| | - Ling Lei
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, USA
| | - Yassemi Capetanaki
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Gauri Tadvalkar
- Department of Ophthalmology, George Washington University, Washington, DC, USA
| | - Sonali Pal-Ghosh
- Department of Ophthalmology, George Washington University, Washington, DC, USA
| | - Mary Ann Stepp
- Department of Ophthalmology, George Washington University, Washington, DC, USA
| | - Paola Bargagna-Mohan
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, USA
| | - Royce Mohan
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, USA.
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12
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Golde T, Huster C, Glaser M, Händler T, Herrmann H, Käs JA, Schnauß J. Glassy dynamics in composite biopolymer networks. SOFT MATTER 2018; 14:7970-7978. [PMID: 30176034 PMCID: PMC6183213 DOI: 10.1039/c8sm01061g] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 07/31/2018] [Indexed: 05/05/2023]
Abstract
The cytoskeleton is a highly interconnected meshwork of strongly coupled subsystems providing mechanical stability as well as dynamic functions to cells. To elucidate the underlying biophysical principles, it is central to investigate not only one distinct functional subsystem but rather their interplay as composite biopolymeric structures. Two of the key cytoskeletal elements are actin and vimentin filaments. Here, we show that composite networks reconstituted from actin and vimentin can be described by a superposition of two non-interacting scaffolds. Arising effects are demonstrated in a scale-spanning frame connecting single filament dynamics to macro-rheological network properties. The acquired results of the linear and non-linear bulk mechanics can be captured within an inelastic glassy wormlike chain model. In contrast to previous studies, we find no emergent effects in these composite networks. Thus, our study paves the way to predict the mechanics of the cytoskeleton based on the properties of its single structural components.
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Affiliation(s)
- Tom Golde
- Peter Debye Institute for Soft Matter Physics
, University of Leipzig
,
04103 Leipzig
, Germany
.
| | - Constantin Huster
- Institute for Theoretical Physics
, University of Leipzig
,
04103 Leipzig
, Germany
| | - Martin Glaser
- Peter Debye Institute for Soft Matter Physics
, University of Leipzig
,
04103 Leipzig
, Germany
.
- Fraunhofer Institute for Cell Therapy and Immunology
,
04103 Leipzig
, Germany
| | - Tina Händler
- Peter Debye Institute for Soft Matter Physics
, University of Leipzig
,
04103 Leipzig
, Germany
.
- Fraunhofer Institute for Cell Therapy and Immunology
,
04103 Leipzig
, Germany
| | - Harald Herrmann
- Molecular Genetics
, German Cancer Research Center
,
69120 Heidelberg
, Germany
- Department of Neuropathology
, University Hospital Erlangen
,
91054
, Erlangen
, Germany
| | - Josef A. Käs
- Peter Debye Institute for Soft Matter Physics
, University of Leipzig
,
04103 Leipzig
, Germany
.
| | - Jörg Schnauß
- Peter Debye Institute for Soft Matter Physics
, University of Leipzig
,
04103 Leipzig
, Germany
.
- Fraunhofer Institute for Cell Therapy and Immunology
,
04103 Leipzig
, Germany
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13
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Danielsson F, Peterson MK, Caldeira Araújo H, Lautenschläger F, Gad AKB. Vimentin Diversity in Health and Disease. Cells 2018; 7:E147. [PMID: 30248895 PMCID: PMC6210396 DOI: 10.3390/cells7100147] [Citation(s) in RCA: 157] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 09/16/2018] [Accepted: 09/17/2018] [Indexed: 12/11/2022] Open
Abstract
Vimentin is a protein that has been linked to a large variety of pathophysiological conditions, including cataracts, Crohn's disease, rheumatoid arthritis, HIV and cancer. Vimentin has also been shown to regulate a wide spectrum of basic cellular functions. In cells, vimentin assembles into a network of filaments that spans the cytoplasm. It can also be found in smaller, non-filamentous forms that can localise both within cells and within the extracellular microenvironment. The vimentin structure can be altered by subunit exchange, cleavage into different sizes, re-annealing, post-translational modifications and interacting proteins. Together with the observation that different domains of vimentin might have evolved under different selection pressures that defined distinct biological functions for different parts of the protein, the many diverse variants of vimentin might be the cause of its functional diversity. A number of review articles have focussed on the biology and medical aspects of intermediate filament proteins without particular commitment to vimentin, and other reviews have focussed on intermediate filaments in an in vitro context. In contrast, the present review focusses almost exclusively on vimentin, and covers both ex vivo and in vivo data from tissue culture and from living organisms, including a summary of the many phenotypes of vimentin knockout animals. Our aim is to provide a comprehensive overview of the current understanding of the many diverse aspects of vimentin, from biochemical, mechanical, cellular, systems biology and medical perspectives.
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Affiliation(s)
- Frida Danielsson
- Science for Life Laboratory, Royal Institute of Technology, 17165 Stockholm, Sweden.
| | | | | | - Franziska Lautenschläger
- Campus D2 2, Leibniz-Institut für Neue Materialien gGmbH (INM) and Experimental Physics, NT Faculty, E 2 6, Saarland University, 66123 Saarbrücken, Germany.
| | - Annica Karin Britt Gad
- Centro de Química da Madeira, Universidade da Madeira, 9020105 Funchal, Portugal.
- Department of Medical Biochemistry and Microbiology, Uppsala University, 75237 Uppsala, Sweden.
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14
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Wazawa T, Arai Y, Kawahara Y, Takauchi H, Washio T, Nagai T. Highly biocompatible super-resolution fluorescence imaging using the fast photoswitching fluorescent protein Kohinoor and SPoD-ExPAN with Lp-regularized image reconstruction. Microscopy (Oxf) 2018; 67:89-98. [PMID: 29409007 DOI: 10.1093/jmicro/dfy004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 01/12/2018] [Indexed: 11/13/2022] Open
Abstract
Far-field super-resolution fluorescence microscopy has enabled us to visualize live cells in great detail and with an unprecedented resolution. However, the techniques developed thus far have required high-power illumination (102-106 W/cm2), which leads to considerable phototoxicity to live cells and hampers time-lapse observation of the cells. In this study we show a highly biocompatible super-resolution microscopy technique that requires a very low-power illumination. The present technique combines a fast photoswitchable fluorescent protein, Kohinoor, with SPoD-ExPAN (super-resolution by polarization demodulation/excitation polarization angle narrowing). With this technique, we successfully observed Kohinoor-fusion proteins involving vimentin, paxillin, histone and clathrin expressed in HeLa cells at a spatial resolution of 70-80 nm with illumination power densities as low as ~1 W/cm2 for both excitation and photoswitching. Furthermore, although the previous SPoD-ExPAN technique used L1-regularized maximum-likelihood calculations to reconstruct super-resolved images, we devised an extension to the Lp-regularization to obtain super-resolved images that more accurately describe objects at the specimen plane. Thus, the present technique would significantly extend the applicability of super-resolution fluorescence microscopy for live-cell imaging.
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Affiliation(s)
- Tetsuichi Wazawa
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Yoshiyuki Arai
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Yoshinobu Kawahara
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Hiroki Takauchi
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Takashi Washio
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Takeharu Nagai
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
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15
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Pang AH, Obiero JM, Kulczyk AW, Sviripa VM, Tsodikov OV. A crystal structure of coil 1B of vimentin in the filamentous form provides a model of a high-order assembly of a vimentin filament. FEBS J 2018; 285:2888-2899. [PMID: 29905014 DOI: 10.1111/febs.14585] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 05/01/2018] [Accepted: 06/13/2018] [Indexed: 12/25/2022]
Abstract
Vimentin is an intermediate filament (IF) protein that is expressed in leukocytes, fibroblasts and endothelial cells of blood vessels. Vimentin filaments contribute to structural stability of the cell membrane, organelle positioning and protein transport. Vimentin self-assembles into a dimer that subsequently forms high-order structures, including tetramers and octamers. The details of IF assembly at crystallographic resolutions are limited to the tetrameric form. We describe a crystal structure of a fragment of a vimentin rod domain (coil 1B) with a dimer of tetramers in the asymmetric unit. Coil 1B in the crystal is in an infinitely high-order filamentous assembly state, in which the tetramers are packed against each other laterally in an antiparallel fashion across the crystal lattice. In one of the directions of lateral packing, the tetramers pack against each other strictly head-to-tail, and in the orthogonal direction the tetramers pack in a staggered manner. This organization of the tetramers of coil 1B in the crystal lattice, together with previously reported biochemical and structural data, yield a model of high-order vimentin filament assembly. DATABASE Structural data are available in the PDB under the accession number 5WHF.
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Affiliation(s)
- Allan H Pang
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA
| | - Josiah M Obiero
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA
| | - Arkadiusz W Kulczyk
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Vitaliy M Sviripa
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, USA
| | - Oleg V Tsodikov
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA
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16
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Mücke N, Kämmerer L, Winheim S, Kirmse R, Krieger J, Mildenberger M, Baßler J, Hurt E, Goldmann WH, Aebi U, Toth K, Langowski J, Herrmann H. Assembly Kinetics of Vimentin Tetramers to Unit-Length Filaments: A Stopped-Flow Study. Biophys J 2018; 114:2408-2418. [PMID: 29754715 DOI: 10.1016/j.bpj.2018.04.032] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 03/20/2018] [Accepted: 04/19/2018] [Indexed: 01/01/2023] Open
Abstract
Intermediate filaments (IFs) are principal components of the cytoskeleton, a dynamic integrated system of structural proteins that provides the functional architecture of metazoan cells. They are major contributors to the elasticity of cells and tissues due to their high mechanical stability and intrinsic flexibility. The basic building block for the assembly of IFs is a rod-like, 60-nm-long tetrameric complex made from two antiparallel, half-staggered coiled coils. In low ionic strength, tetramers form stable complexes that rapidly assemble into filaments upon raising the ionic strength. The first assembly products, "frozen" by instantaneous chemical fixation and viewed by electron microscopy, are 60-nm-long "unit-length" filaments (ULFs) that apparently form by lateral in-register association of tetramers. ULFs are the active elements of IF growth, undergoing longitudinal end-to-end annealing with one another and with growing filaments. Originally, we have employed quantitative time-lapse atomic force and electron microscopy to analyze the kinetics of vimentin-filament assembly starting from a few seconds to several hours. To obtain detailed quantitative insight into the productive reactions that drive ULF formation, we now introduce a "stopped-flow" approach in combination with static light-scattering measurements. Thereby, we determine the basic rate constants for lateral assembly of tetramers to ULFs. Processing of the recorded data by a global fitting procedure enables us to describe the hierarchical steps of IF formation. Specifically, we propose that tetramers are consumed within milliseconds to yield octamers that are obligatory intermediates toward ULF formation. Although the interaction of tetramers is diffusion controlled, it is strongly driven by their geometry to mediate effective subunit targeting. Importantly, our model conclusively reflects the previously described occurrence of polymorphic ULF and mature filaments in terms of their number of tetramers per cross section.
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Affiliation(s)
- Norbert Mücke
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Lara Kämmerer
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Stefan Winheim
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Robert Kirmse
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Jan Krieger
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Maria Mildenberger
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Jochen Baßler
- Biochemistry Center of Heidelberg University, Heidelberg, Germany
| | - Ed Hurt
- Biochemistry Center of Heidelberg University, Heidelberg, Germany
| | - Wolfgang H Goldmann
- Department of Physics, Biophysics group, Friedrich-Alexander-University of Erlangen-Nuremberg, Erlangen, Germany
| | - Ueli Aebi
- Biozentrum, University of Basel, Basel, Switzerland
| | - Katalin Toth
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Jörg Langowski
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Harald Herrmann
- Institute of Neuropathology, University Hospital Erlangen, Erlangen, Germany; Division of Molecular Genetics, German Cancer Research Center, Heidelberg, Germany.
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17
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Sharma S, Conover GM, Elliott JL, Der Perng M, Herrmann H, Quinlan RA. αB-crystallin is a sensor for assembly intermediates and for the subunit topology of desmin intermediate filaments. Cell Stress Chaperones 2017; 22:613-626. [PMID: 28470624 PMCID: PMC5465037 DOI: 10.1007/s12192-017-0788-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 03/07/2017] [Accepted: 03/16/2017] [Indexed: 12/04/2022] Open
Abstract
Mutations in the small heat shock protein chaperone CRYAB (αB-crystallin/HSPB5) and the intermediate filament protein desmin, phenocopy each other causing cardiomyopathies. Whilst the binding sites for desmin on CRYAB have been determined, desmin epitopes responsible for CRYAB binding and also the parameters that determine CRYAB binding to desmin filaments are unknown. Using a combination of co-sedimentation centrifugation, viscometric assays and electron microscopy of negatively stained filaments to analyse the in vitro assembly of desmin filaments, we show that the binding of CRYAB to desmin is subject to its assembly status, to the subunit organization within filaments formed and to the integrity of the C-terminal tail domain of desmin. Our in vitro studies using a rapid assembly protocol, C-terminally truncated desmin and two disease-causing mutants (I451M and R454W) suggest that CRYAB is a sensor for the surface topology of the desmin filament. Our data also suggest that CRYAB performs an assembly chaperone role because the assembling filaments have different CRYAB-binding properties during the maturation process. We suggest that the capability of CRYAB to distinguish between filaments with different surface topologies due either to mutation (R454W) or assembly protocol is important to understanding the pathomechanism(s) of desmin-CRYAB myopathies.
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Affiliation(s)
- Sarika Sharma
- Division of Molecular Genetics, German Cancer Research Center, Heidelberg, Germany
| | - Gloria M Conover
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
| | - Jayne L Elliott
- Department of Biosciences and the Biophysical Sciences Institute, University of Durham, Durham, UK
| | - Ming Der Perng
- Institute of Molecular Medicine, College of Life Sciences, National Tsing Hua University, Hsinchu, 300, Taiwan
| | - Harald Herrmann
- Division of Molecular Genetics, German Cancer Research Center, Heidelberg, Germany
- Institute of Neuropathology, University Hospital Erlangen, Erlangen, Germany
| | - Roy A Quinlan
- Department of Biosciences and the Biophysical Sciences Institute, University of Durham, Durham, UK.
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18
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Leduc C, Etienne-Manneville S. Regulation of microtubule-associated motors drives intermediate filament network polarization. J Cell Biol 2017; 216:1689-1703. [PMID: 28432079 PMCID: PMC5461013 DOI: 10.1083/jcb.201607045] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 01/16/2017] [Accepted: 03/03/2017] [Indexed: 11/22/2022] Open
Abstract
Intermediate filaments (IFs) are key players in the control of cell morphology and structure as well as in active processes such as cell polarization, migration, and mechanoresponses. However, the regulatory mechanisms controlling IF dynamics and organization in motile cells are still poorly understood. In this study, we investigate the mechanisms leading to the polarized rearrangement of the IF network along the polarity axis. Using photobleaching and photoconversion experiments in glial cells expressing vimentin, glial fibrillary acidic protein, and nestin, we show that the distribution of cytoplasmic IFs results from a continuous turnover based on the cooperation of an actin-dependent retrograde flow and anterograde and retrograde microtubule-dependent transports. During wound-induced astrocyte polarization, IF transport becomes directionally biased from the cell center toward the cell front. Such asymmetry in the transport is mainly caused by a Cdc42- and atypical PKC-dependent inhibition of dynein-dependent retrograde transport. Our results show how polarity signaling can affect the dynamic turnover of the IF network to promote the polarization of the network itself.
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Affiliation(s)
- Cécile Leduc
- Institut Pasteur Paris, Cell Polarity, Migration and Cancer Unit, UMR 3691, Equipe Labellisée Ligue Contre le Cancer, Centre National de la Recherché Scientifique, 75724 Paris, France
| | - Sandrine Etienne-Manneville
- Institut Pasteur Paris, Cell Polarity, Migration and Cancer Unit, UMR 3691, Equipe Labellisée Ligue Contre le Cancer, Centre National de la Recherché Scientifique, 75724 Paris, France.
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19
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Abstract
Intermediate filaments (IFs), together with microtubules and actin microfilaments, are the three main cytoskeletal components in metazoan cells. IFs are formed by a distinct protein family, which is made up of 70 members in humans. Most IF proteins are tissue- or organelle-specific, which includes lamins, the IF proteins of the nucleus. The building block of IFs is an elongated dimer, which consists of a central α-helical 'rod' domain flanked by flexible N- and C-terminal domains. The conserved rod domain is the 'signature feature' of the IF family. Bioinformatics analysis reveals that the rod domain of all IF proteins contains three α-helical segments of largely conserved length, interconnected by linkers. Moreover, there is a conserved pattern of hydrophobic repeats within each segment, which includes heptads and hendecads. This defines the presence of both left-handed and almost parallel coiled-coil regions along the rod length. Using X-ray crystallography on multiple overlapping fragments of IF proteins, the atomic structure of the nearly complete rod domain has been determined. Here, we discuss some specific challenges of this procedure, such as crystallization and diffraction data phasing by molecular replacement. Further insights into the structure of the coiled coil and the terminal domains have been obtained using electron paramagnetic resonance measurements on the full-length protein, with spin labels attached at specific positions. This atomic resolution information, as well as further interesting findings, such as the variation of the coiled-coil stability along the rod length, provide clues towards interpreting the data on IF assembly, collected by a range of methods. However, a full description of this process at the molecular level is not yet at hand.
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Affiliation(s)
- Dmytro Guzenko
- Laboratory for Biocrystallography, Department of Pharmaceutical and Pharmacological Sciences, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Anastasia A Chernyatina
- Laboratory for Biocrystallography, Department of Pharmaceutical and Pharmacological Sciences, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Sergei V Strelkov
- Laboratory for Biocrystallography, Department of Pharmaceutical and Pharmacological Sciences, Katholieke Universiteit Leuven, Leuven, Belgium.
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20
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Gentil BJ, Tibshirani M, Durham HD. Neurofilament dynamics and involvement in neurological disorders. Cell Tissue Res 2015; 360:609-20. [PMID: 25567110 DOI: 10.1007/s00441-014-2082-7] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 11/19/2014] [Indexed: 12/21/2022]
Abstract
Neurons are extremely polarised cells in which the cytoskeleton, composed of microtubules, microfilaments and neurofilaments, plays a crucial role in maintaining structure and function. Neurofilaments, the 10-nm intermediate filaments of neurons, provide structure and mechanoresistance but also provide a scaffolding for the organization of the nucleus and organelles such as mitochondria and ER. Disruption of neurofilament organization and expression or metabolism of neurofilament proteins is characteristic of certain neurological syndromes including Amyotrophic Lateral Sclerosis, Charcot-Marie-Tooth sensorimotor neuropathies and Giant Axonal Neuropathy. Microfluorometric live imaging techniques have been instrumental in revealing the dynamics of neurofilament assembly and transport and their functions in organizing intracellular organelle networks. The insolubility of neurofilament proteins has limited identifying interactors by conventional biochemical techniques but yeast two-hybrid experiments have revealed new roles for oligomeric, nonfilamentous structures including vesicular trafficking. Although having long half-lives, new evidence points to degradation of subunits by the ubiquitin-proteasome system as a mechanism of normal turnover. Although certain E3-ligases ubiquitinating neurofilament proteins have been identified, the overall process of neurofilament degradation is not well understood. We review these mechanisms of neurofilament homeostasis and abnormalities in motor neuron and peripheral nerve disorders. Much remains to discover about the disruption of processes that leads to their pathological aggregation and accumulation and the relevance to pathogenesis. Understanding these mechanisms is crucial for identifying novel therapeutic strategies.
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Affiliation(s)
- Benoit J Gentil
- Department of Neurology/Neurosurgery and Montreal Neurological Institute, McGill University, Montreal, QC, H3A 2B4, Canada,
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21
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Fu T, Guerette PA, Tan RYT, Zhao H, Schefer L, Mezzenga R, Miserez A. Biomimetic self-assembly of recombinant marine snail egg capsule proteins into structural coiled-coil units. J Mater Chem B 2015; 3:2671-2684. [DOI: 10.1039/c4tb01434k] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
We report on the biomimetic production of shock-absorbing proteins from marine snail egg capsules and their self-assembly into coiled-coil filaments.
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Affiliation(s)
- Tianpei Fu
- School of Material Science and Engineering
- Nanyang Technological University (NTU)
- Singapore
- Center for Biomimetic Sensor Science
- NTU
| | - Paul A. Guerette
- School of Material Science and Engineering
- Nanyang Technological University (NTU)
- Singapore
- Center for Biomimetic Sensor Science
- NTU
| | - Raymond Y. T. Tan
- School of Material Science and Engineering
- Nanyang Technological University (NTU)
- Singapore
| | - Hua Zhao
- Institute of Chemical and Engineering Sciences (ICES)
- Agency for Science, Technology, and Research (A*Star)
- Singapore
| | - Larissa Schefer
- Department of Health Sciences and Technology
- Swiss Federal Institute of Technology in Zurich (ETHZ)
- 8092 Zürich
- Switzerland
| | - Raffaele Mezzenga
- Department of Health Sciences and Technology
- Swiss Federal Institute of Technology in Zurich (ETHZ)
- 8092 Zürich
- Switzerland
| | - Ali Miserez
- School of Material Science and Engineering
- Nanyang Technological University (NTU)
- Singapore
- Center for Biomimetic Sensor Science
- NTU
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22
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Abstract
We have shown previously that neurofilaments and vimentin filaments expressed in nonneuronal cell lines can lengthen by joining ends in a process known as "end-to-end annealing." To test if this also occurs for neurofilaments in neurons, we transfected cultured rat cortical neurons with fluorescent neurofilament fusion proteins and then used photoconversion or photoactivation strategies to create distinct populations of red and green fluorescent filaments. Within several hours we observed the appearance of chimeric filaments consisting of alternating red and green segments, which is indicative of end-to-end annealing of red and green filaments. However, the appearance of these chimeric filaments was accompanied by a gradual fragmentation of the red and green filament segments, which is indicative of severing. Over time we observed a progressive increase in the number of red-green junctions along the filaments accompanied by a progressive decrease in the average length of the alternating red and green fluorescent segments that comprised those filaments, suggesting a dynamic cycle of severing and end-to-end-annealing. Time-lapse imaging of the axonal transport of chimeric filaments demonstrated that the red and green segments moved together, confirming that they were indeed part of the same filament. Moreover, in several instances, we also were able to capture annealing and severing events live in time-lapse movies. We propose that the length of intermediate filaments in cells is regulated by the opposing actions of severing and end-to-end annealing, and we speculate that this regulatory mechanism may influence neurofilament transport within axons.
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23
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Müller SA, Engel A. Looking back at a quarter-century of research at the Maurice E. Müller Institute for Structural Biology. J Struct Biol 2011; 177:3-13. [PMID: 22115996 DOI: 10.1016/j.jsb.2011.11.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Revised: 11/04/2011] [Accepted: 11/05/2011] [Indexed: 10/15/2022]
Abstract
The Maurice E. Müller Institute, embedded in the infrastructure of the Biozentrum, University of Basel, was founded in 1985 and financed by the Maurice E. Müller Foundation of Switzerland. For 26 years its two founders, Ueli Aebi and Andreas Engel, pursued the vision of integrated structural biology. This paper reviews selected publications issuing from the Maurice E. Müller Institute for Structural Biology and marks the end of this era.
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Affiliation(s)
- Shirley A Müller
- Center for Cellular Imaging and Nano Analytics, Biozentrum, University of Basel, Mattenstrasse 26, CH-4058 Basel, Switzerland
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24
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The nanomechanical properties of rat fibroblasts are modulated by interfering with the vimentin intermediate filament system. J Struct Biol 2011; 174:476-84. [DOI: 10.1016/j.jsb.2011.03.011] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 03/05/2011] [Accepted: 03/15/2011] [Indexed: 11/20/2022]
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25
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Deconstructing the late phase of vimentin assembly by total internal reflection fluorescence microscopy (TIRFM). PLoS One 2011; 6:e19202. [PMID: 21544245 PMCID: PMC3081349 DOI: 10.1371/journal.pone.0019202] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 03/23/2011] [Indexed: 11/23/2022] Open
Abstract
Quantitative imaging of intermediate filaments (IF) during the advanced phase of the assembly process is technically difficult, since the structures are several µm long and therefore they exceed the field of view of many electron (EM) or atomic force microscopy (AFM) techniques. Thereby quantitative studies become extremely laborious and time-consuming. To overcome these difficulties, we prepared fluorescently labeled vimentin for visualization by total internal reflection fluorescence microscopy (TIRFM). In order to investigate if the labeling influences the assembly properties of the protein, we first determined the association state of unlabeled vimentin mixed with increasing amounts of labeled vimentin under low ionic conditions by analytical ultracentrifugation. We found that bona fide tetrameric complexes were formed even when half of the vimentin was labeled. Moreover, we demonstrate by quantitative atomic force microscopy and electron microscopy that the morphology and the assembly properties of filaments were not affected when the fraction of labeled vimentin was below 10%. Using fast frame rates we observed the rapid deposition of fluorescently labeled IFs on glass supports by TIRFM in real time. By tracing their contours, we have calculated the persistence length of long immobilized vimentin IFs to 1 µm, a value that is identical to those determined for shorter unlabeled vimentin. These results indicate that the structural properties of the filaments were not affected significantly by the dye. Furthermore, in order to analyze the late elongation phase, we mixed long filaments containing either Alexa 488- or Alexa 647-labeled vimentin. The ‘patchy’ structure of the filaments obtained unambiguously showed the elongation of long IFs through direct end-to-end annealing of individual filaments.
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26
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Esue O, Rupprecht L, Sun SX, Wirtz D. Dynamics of the bacterial intermediate filament crescentin in vitro and in vivo. PLoS One 2010; 5:e8855. [PMID: 20140233 PMCID: PMC2816638 DOI: 10.1371/journal.pone.0008855] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Accepted: 01/04/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Crescentin, the recently discovered bacterial intermediate filament protein, organizes into an extended filamentous structure that spans the length of the bacterium Caulobacter crescentus and plays a critical role in defining its curvature. The mechanism by which crescentin mediates cell curvature and whether crescentin filamentous structures are dynamic and/or polar are not fully understood. METHODOLOGY/PRINCIPAL FINDINGS Using light microscopy, electron microscopy and quantitative rheology, we investigated the mechanics and dynamics of crescentin structures. Live-cell microscopy reveals that crescentin forms structures in vivo that undergo slow remodeling. The exchange of subunits between these structures and a pool of unassembled subunits is slow during the life cycle of the cell however; in vitro assembly and gelation of C. crescentus crescentin structures are rapid. Moreover, crescentin forms filamentous structures that are elastic, solid-like, and, like other intermediate filaments, can recover a significant portion of their network elasticity after shear. The assembly efficiency of crescentin is largely unaffected by monovalent cations (K(+), Na(+)), but is enhanced by divalent cations (Mg(2+), Ca(2+)), suggesting that the assembly kinetics and micromechanics of crescentin depend on the valence of the ions present in solution. CONCLUSIONS/SIGNIFICANCE These results indicate that crescentin forms filamentous structures that are elastic, labile, and stiff, and that their low dissociation rate from established structures controls the slow remodeling of crescentin in C. crescentus.
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Affiliation(s)
- Osigwe Esue
- Department of Pharmaceutical Development, Genentech, South San Francisco, California, United States of America.
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27
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Kirmse R, Bouchet-Marquis C, Page C, Hoenger A. Three-dimensional cryo-electron microscopy on intermediate filaments. Methods Cell Biol 2010; 96:565-89. [PMID: 20869538 DOI: 10.1016/s0091-679x(10)96023-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Together with microtubules and actin filaments (F-actin), intermediate filaments (IFs) form the cytoskeleton of metazoan cells. However, unlike the other two entities that are extremely conserved, IFs are much more diverse and are grouped into five different families. In contrast to microtubules and F-actin, IFs do not exhibit a polarity, which may be the reason that no molecular motors travel along them. The molecular structure of IFs is less well resolved than that of the other cytoskeletal systems. This is partially due to their functional variability, tissue-specific expression, and their intrinsic structural properties. IFs are composed mostly of relatively smooth protofibrils formed by antiparallel arranged α-helical coiled-coil bundles flanked by small globular domains at either end. These features make them difficult to study by various electron microscopy methods or atomic force microscopy (AFM). Furthermore, the elongated shape of monomeric or dimeric IF units interferes with the formation of highly ordered three-dimensional (3-D) crystals suitable for atomic resolution crystallography. So far, most of the data we currently have on IF macromolecular structures come from electron microscopy of negatively stained samples, and fragmented α-helical coiled-coil units solved by X-ray diffraction. In addition, AFM allows the observation of the dynamic states of IFs in solution and delivers a new view into the assembly properties of IFs. Here, we discuss the applicability of cryo-electron microscopy (cryo-EM) and cryo-electron tomography (cryo-ET) for the field. Both methods are strongly related and have only recently been applied to IFs. However, cryo-EM revealed distinct new features within IFs that have not been seen before, and cryo-ET adds a 3-D view of IFs revealing the path and number of protofilaments within the various IF assemblies.
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Affiliation(s)
- Robert Kirmse
- The Boulder Laboratory for 3-D Microscopy of Cells, University of Colorado at Boulder, Boulder, Colorado 80309-0347, USA
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Mücke N, Klenin K, Kirmse R, Bussiek M, Herrmann H, Hafner M, Langowski J. Filamentous biopolymers on surfaces: atomic force microscopy images compared with Brownian dynamics simulation of filament deposition. PLoS One 2009; 4:e7756. [PMID: 19888472 PMCID: PMC2768466 DOI: 10.1371/journal.pone.0007756] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Accepted: 09/30/2009] [Indexed: 11/19/2022] Open
Abstract
Nanomechanical properties of filamentous biopolymers, such as the persistence length, may be determined from two-dimensional images of molecules immobilized on surfaces. For a single filament in solution, two principal adsorption scenarios are possible. Both scenarios depend primarly on the interaction strength between the filament and the support: i) For interactions in the range of the thermal energy, the filament can freely equilibrate on the surface during adsorption; ii) For interactions much stronger than the thermal energy, the filament will be captured by the surface without having equilibrated. Such a ‘trapping’ mechanism leads to more condensed filament images and hence to a smaller value for the apparent persistence length. To understand the capture mechanism in more detail we have performed Brownian dynamics simulations of relatively short filaments by taking the two extreme scenarios into account. We then compared these ‘ideal’ adsorption scenarios with observed images of immobilized vimentin intermediate filaments on different surfaces. We found a good agreement between the contours of the deposited vimentin filaments on mica (‘ideal’ trapping) and on glass (‘ideal’ equilibrated) with our simulations. Based on these data, we have developed a strategy to reliably extract the persistence length of short worm-like chain fragments or network forming filaments with unknown polymer-surface interactions.
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Affiliation(s)
- Norbert Mücke
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Konstantin Klenin
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Robert Kirmse
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Malte Bussiek
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Harald Herrmann
- Department of Molecular Genetics, German Cancer Research Center, Heidelberg, Germany
| | - Mathias Hafner
- Institute of Molecular and Cell Biology, University of Applied Sciences Mannheim, Mannheim, Germany
| | - Jörg Langowski
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
- * E-mail:
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Disease mutations in the “head” domain of the extra-sarcomeric protein desmin distinctly alter its assembly and network-forming properties. J Mol Med (Berl) 2009; 87:1207-19. [DOI: 10.1007/s00109-009-0521-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2009] [Revised: 08/08/2009] [Accepted: 08/11/2009] [Indexed: 10/20/2022]
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Portet S, Mücke N, Kirmse R, Langowski J, Beil M, Herrmann H. Vimentin intermediate filament formation: in vitro measurement and mathematical modeling of the filament length distribution during assembly. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:8817-23. [PMID: 20050052 DOI: 10.1021/la900509r] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The salt-induced in vitro assembly of cytoplasmic intermediate filament (IF) proteins such as vimentin is characterized by a very rapid lateral association of soluble tetrameric subunits into 60-nm-long full-width "unit-length" filaments (ULFs). We have demonstrated for this prototype IF protein that filament elongation occurs by the longitudinal annealing of ULFs into short IFs. These IFs further longitudinally anneal and thus constitute a progressively elongating filament population that over time yields filaments of several microm in length. Previously, we provided a mathematical model for the kinetics of the assembly process based on the average length distribution of filaments as determined by time-lapse electron and atomic force microscopy. Thereby, we were able to substantiate the concept that end-to-end-annealing of both ULFs and short filaments is obligatory for the formation of long IFs (Kirmse, R.; Portet, S.; Mücke, N. Aebi, U.; Herrmann, H.; Langowski, J. J. Biol. Chem. 2007, 282, 18563-18572). As the next step in understanding the mechanics of IF formation, we have expanded our mathematical model to describe the quantitative aspects of IF assembly by taking into account geometry constraints as well as the diffusion properties of rodlike linear aggregates. Thereby, we have developed a robust model for the time-dependent filament length distribution of IFs under standard conditions.
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Affiliation(s)
- Stéphanie Portet
- Department of Mathematics, 342 Machray Hall, University of Manitoba, Winnipeg, MB, Canada R3L 2N2.
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31
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Colakoğlu G, Brown A. Intermediate filaments exchange subunits along their length and elongate by end-to-end annealing. ACTA ACUST UNITED AC 2009; 185:769-77. [PMID: 19468066 PMCID: PMC2711597 DOI: 10.1083/jcb.200809166] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Actin filaments and microtubules lengthen and shorten by addition and loss of subunits at their ends, but it is not known whether this is also true for intermediate filaments. In fact, several studies suggest that in vivo, intermediate filaments may lengthen by end-to-end annealing and that addition and loss of subunits is not confined to the filament ends. To test these hypotheses, we investigated the assembly dynamics of neurofilament and vimentin intermediate filament proteins in cultured cells using cell fusion, photobleaching, and photoactivation strategies in combination with conventional and photoactivatable fluorescent fusion proteins. We show that neurofilaments and vimentin filaments lengthen by end-to-end annealing of assembled filaments. We also show that neurofilaments and vimentin filaments incorporate subunits along their length by intercalation into the filament wall with no preferential addition of subunits to the filament ends, a process which we term intercalary subunit exchange.
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Affiliation(s)
- Gülsen Colakoğlu
- Center for Molecular Neurobiology, The Ohio State University, Columbus, OH 43210, USA
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32
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Desmin and vimentin intermediate filament networks: their viscoelastic properties investigated by mechanical rheometry. J Mol Biol 2009; 388:133-43. [PMID: 19281820 DOI: 10.1016/j.jmb.2009.03.005] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Revised: 03/02/2009] [Accepted: 03/03/2009] [Indexed: 02/01/2023]
Abstract
We have investigated the viscoelastic properties of the cytoplasmic intermediate filament (IF) proteins desmin and vimentin. Mechanical measurements were supported by time-dependent electron microscopy studies of the assembly process under similar conditions. Network formation starts within 2 min, but it takes more than 30 min until equilibrium mechanical network strength is reached. Filament bundling is more pronounced for desmin than for vimentin. Desmin filaments (persistence length l(p) approximately 900 nm) are stiffer than vimentin filaments (l(p) approximately 400 nm), but both IFs are much more flexible than microfilaments. The concentration dependence of the plateau modulus G(0) approximately c(alpha) is much weaker than predicted theoretically for networks of semiflexible filaments. This is more pronounced for vimentin (alpha=0.47) than for desmin (alpha=0.70). Both networks exhibit strain stiffening at large shear deformations. At the transition from linear to nonlinear viscoelastic response, only desmin shows characteristics of nonaffine network deformation. Strain stiffening and the maximum modulus occur at strain amplitudes about an order of magnitude larger than those for microfilaments. This is probably attributable to axial slippage within the tetramer building blocks of the IFs. Network deformation beyond a critical strain gamma(max) results in irreversible damage. Strain stiffening sets in at lower concentrations, is more pronounced, and is less sensitive to ionic strength for desmin than for vimentin. Hence, desmin exhibits strain stiffening even at low-salt concentrations, which is not observed for vimentin, and we conclude that the strength of electrostatic repulsion compared to the strength of attractive interactions forming the network junctions is significantly weaker for desmin than for vimentin filaments. These findings indicate that both IFs exhibit distinct mechanical properties that are adapted to their respective cellular surroundings [i.e., myocytes (desmin) and fibroblasts (vimentin)].
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A heterospecific leucine zipper tetramer. ACTA ACUST UNITED AC 2008; 15:908-19. [PMID: 18804028 PMCID: PMC7111190 DOI: 10.1016/j.chembiol.2008.07.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2008] [Revised: 07/07/2008] [Accepted: 07/10/2008] [Indexed: 11/21/2022]
Abstract
Protein-protein interactions dictate the assembly of the macromolecular complexes essential for functional networks and cellular behavior. Elucidating principles of molecular recognition governing important interfaces such as coiled coils is a challenging goal for structural and systems biology. We report here that two valine-containing mutants of the GCN4 leucine zipper that fold individually as four-stranded coiled coils associate preferentially in mixtures to form an antiparallel, heterotetrameric structure. X-ray crystallographic analysis reveals that the coinciding hydrophobic interfaces of the hetero- and homotetramers differ in detail, explaining their partnering and structural specificity. Equilibrium disulfide exchange and thermal denaturation experiments show that the 50-fold preference for heterospecificity results from a combination of preferential packing and hydrophobicity. The extent of preference is sensitive to the side chains comprising the interface. Thus, heterotypic versus homotypic interaction specificity in coiled coils reflects a delicate balance in complementarity of shape and chemistry of the participating side chains.
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Müller SA, Aebi U, Engel A. What transmission electron microscopes can visualize now and in the future. J Struct Biol 2008; 163:235-45. [PMID: 18614377 DOI: 10.1016/j.jsb.2008.05.008] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Accepted: 05/21/2008] [Indexed: 11/18/2022]
Abstract
Our review concentrates on the progress made in high-resolution transmission electron microscopy (TEM) in the past decade. This includes significant improvements in sample preparation by quick-freezing aimed at preserving the specimen in a close-to-native state in the high vacuum of the microscope. Following advances in cold stage and TEM vacuum technology systems, the observation of native, frozen hydrated specimens has become a widely used approach. It fostered the development of computer guided, fully automated low-dose data acquisition systems allowing matched pairs of images and diffraction patterns to be recorded for electron crystallography, and the collection of entire tilt-series for electron tomography. To achieve optimal information transfer to atomic resolution, field emission electron guns combined with acceleration voltages of 200-300 kV are now routinely used. The outcome of these advances is illustrated by the atomic structure of mammalian aquaporin-O and by the pore-forming bacterial cytotoxin ClyA resolved to 12 A. Further, the Yersinia injectisome needle, a bacterial pseudopilus and the binding of phalloidin to muscle actin filaments were chosen to document the advantage of the high contrast offered by dedicated scanning transmission electron microscopy (STEM) and/or the STEM's ability to measure the mass of protein complexes and directly link this to their shape. Continued progress emerging from leading research laboratories and microscope manufacturers will eventually enable us to determine the proteome of a single cell by electron tomography, and to more routinely solve the atomic structure of membrane proteins by electron crystallography.
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Affiliation(s)
- Shirley A Müller
- Maurice E. Müller Institute for Structural Biology, Biozentrum, University of Basel, Klingelbergstr. 70, CH-4056 Basel, Switzerland.
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35
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Abstract
The intermediate filament (IF) network is one of the three cytoskeletal systems in smooth muscle. The type III IF proteins vimentin and desmin are major constituents of the network in smooth muscle cells and tissues. Lack of vimentin or desmin impairs contractile ability of various smooth muscle preparations, implying their important role for smooth muscle force development. The IF framework has long been viewed as a fixed cytostructure that solely provides mechanical integrity for the cell. However, recent studies suggest that the IF cytoskeleton is dynamic in mammalian cells in response to various external stimulation. In this review, the structure and biological properties of IF proteins in smooth muscle are summarized. The role of IF proteins in the modulation of smooth muscle force development and redistribution/translocation of signaling partners (such as p130 Crk-associated substrate, CAS) is depicted. This review also summarizes our latest understanding on how the IF network may be regulated in smooth muscle.
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Affiliation(s)
- Dale D Tang
- Center for Cardiovascular Sciences, Albany Medical College, Albany, NY 12208, USA.
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Hull E, Spoja C, Cordova M, Cohlberg JA. Neurofilament protein aggregation in a cell line model system. Biochem Biophys Res Commun 2008; 366:73-9. [DOI: 10.1016/j.bbrc.2007.11.105] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2007] [Accepted: 11/15/2007] [Indexed: 10/22/2022]
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37
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Kreplak L, Richter K, Aebi U, Herrmann H. Chapter 15 Electron Microscopy of Intermediate Filaments: Teaming up with Atomic Force and Confocal Laser Scanning Microscopy. Methods Cell Biol 2008; 88:273-97. [DOI: 10.1016/s0091-679x(08)00415-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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38
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Norlén L, Masich S, Goldie KN, Hoenger A. Structural analysis of vimentin and keratin intermediate filaments by cryo-electron tomography. Exp Cell Res 2007; 313:2217-27. [PMID: 17499715 DOI: 10.1016/j.yexcr.2007.03.037] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2007] [Revised: 03/20/2007] [Accepted: 03/26/2007] [Indexed: 11/25/2022]
Abstract
Intermediate filaments are a large and structurally diverse group of cellular filaments that are classified into five different groups. They are referred to as intermediate filaments (IFs) because they are intermediate in diameter between the two other cytoskeletal filament systems that is filamentous actin and microtubules. The basic building block of IFs is a predominantly alpha-helical rod with variable length globular N- and C-terminal domains. On the ultra-structural level there are two major differences between IFs and microtubules or actin filaments: IFs are non-polar, and they do not exhibit large globular domains. IF molecules associate via a coiled-coil interaction into dimers and higher oligomers. Structural investigations into the molecular building plan of IFs have been performed with a variety of biophysical and imaging methods such as negative staining and metal-shadowing electron microscopy (EM), mass determination by scanning transmission EM, X-ray crystallography on fragments of the IF stalk and low-angle X-ray scattering. The actual packing of IF dimers into a long filament varies between the different families. Typically the dimers form so called protofibrils that further assemble into a filament. Here we introduce new cryo-imaging methods for structural investigations of IFs in vitro and in vivo, i.e., cryo-electron microscopy and cryo-electron tomography, as well as associated techniques such as the preparation and handling of vitrified sections of cellular specimens.
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Affiliation(s)
- Lars Norlén
- Medical Nobel Institute, Department of Cellular and Molecular Biology (CMB), Karolinska Institute, and Dermatology Clinic, Karolinska University Hospital, Stockholm, Sweden.
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Goldie KN, Wedig T, Mitra AK, Aebi U, Herrmann H, Hoenger A. Dissecting the 3-D structure of vimentin intermediate filaments by cryo-electron tomography. J Struct Biol 2006; 158:378-85. [PMID: 17289402 DOI: 10.1016/j.jsb.2006.12.007] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Revised: 12/19/2006] [Accepted: 12/20/2006] [Indexed: 12/21/2022]
Abstract
Vimentin polymerizes via complex lateral interactions of coiled-coil dimers into long, flexible filaments referred to as intermediate filaments (IFs). Intermediate in diameter between microtubules and microfilaments, IFs constitute the third cytoskeletal filament system of metazoan cells. Here we investigated the molecular basis of the 3-D architecture of vimentin IFs by cryo-electron microscopy (cryo-EM) as well as cryo-electron tomography (Cryo-ET) 3-D reconstruction. We demonstrate that vimentin filaments in cross-section exhibit predominantly a four-stranded protofibrilar organization with a right-handed supertwist with a helical pitch of about 96 nm. Compact filaments imaged by cryo-EM appear surprisingly straight and hence appear very stiff. In addition, IFs exhibited an increased flexibility at sites of partial unraveling. This is in strong contrast to chemically fixed, negatively stained preparations of vimentin filaments that generally exhibit smooth bending without untwisting. At some point along the filament unraveling may be triggered and propagates in a cooperative manner so that long stretches of filaments appear to have unraveled rapidly in a coordinated fashion.
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Affiliation(s)
- Kenneth N Goldie
- Structural and Computational Biology Unit, European Molecular Biology Lab, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
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40
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Esue O, Carson AA, Tseng Y, Wirtz D. A direct interaction between actin and vimentin filaments mediated by the tail domain of vimentin. J Biol Chem 2006; 281:30393-9. [PMID: 16901892 DOI: 10.1074/jbc.m605452200] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The assembly and organization of the three major eukaryotic cytoskeleton proteins, actin, microtubules, and intermediate filaments, are highly interdependent. Through evolution, cells have developed specialized multifunctional proteins that mediate the cross-linking of these cytoskeleton filament networks. Here we test the hypothesis that two of these filamentous proteins, F-actin and vimentin filament, can interact directly, i.e. in the absence of auxiliary proteins. Through quantitative rheological studies, we find that a mixture of vimentin/actin filament network features a significantly higher stiffness than that of networks containing only actin filaments or only vimentin filaments. Maximum inter-filament interaction occurs at a vimentin/actin molar ratio of 3 to 1. Mixed networks of actin and tailless vimentin filaments show low mechanical stiffness and much weaker inter-filament interactions. Together with the fact that cells featuring prominent vimentin and actin networks are much stiffer than their counterparts lacking an organized actin or vimentin network, these results suggest that actin and vimentin filaments can interact directly through the tail domain of vimentin and that these inter-filament interactions may contribute to the overall mechanical integrity of cells and mediate cytoskeletal cross-talk.
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Affiliation(s)
- Osigwe Esue
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
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41
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Bär H, Kostareva A, Sjöberg G, Sejersen T, Katus HA, Herrmann H. Forced expression of desmin and desmin mutants in cultured cells: impact of myopathic missense mutations in the central coiled-coil domain on network formation. Exp Cell Res 2006; 312:1554-65. [PMID: 16519886 DOI: 10.1016/j.yexcr.2006.01.021] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2005] [Revised: 01/17/2006] [Accepted: 01/18/2006] [Indexed: 01/24/2023]
Abstract
We recently demonstrated that inherited disease-causing mutations clustered in the alpha-helical coiled-coil "rod" domain of the muscle-specific intermediate filament (IF) protein desmin display a wide range of inhibitory effects on regular in vitro assembly. In these studies, we showed that individual mutations exhibited phenotypes that were not, with respect to the severity of interference, predictable by our current knowledge of the structural design of IF proteins. Moreover, the behavior of some mutated proteins in a standard tissue culture cell expression system was found to be even more complex. Here, we systematically investigate the behavior of these disease mutants in four different cell types: three not containing desmin or the related IF protein vimentin and the standard fibroblast line 3T3, which has an extensive vimentin system. The ability of the mutants to form filaments in the vimentin-free cells varies considerably, and only the mutants forming IFs in vitro generate extended filamentous networks. Furthermore, these latter mutants integrate into the 3T3 vimentin network but all the others do not. Instead, they cause the endogenous network of 3T3 vimentin to reorganize into perinuclear bundles. In addition, most of these assembly-deficient mutant desmins completely segregate from the vimentin system. Instead, the small round to fibrillar particles formed distribute independently throughout the cytoplasm as well as between the collapsed vimentin filament arrays in the perinuclear area.
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Affiliation(s)
- Harald Bär
- Department of Cardiology, University of Heidelberg, D-69120 Heidelberg, Germany
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Bär H, Mücke N, Kostareva A, Sjöberg G, Aebi U, Herrmann H. Severe muscle disease-causing desmin mutations interfere with in vitro filament assembly at distinct stages. Proc Natl Acad Sci U S A 2005; 102:15099-104. [PMID: 16217025 PMCID: PMC1250230 DOI: 10.1073/pnas.0504568102] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Desmin is the major intermediate filament (IF) protein of muscle. Recently, mutations of the desmin gene have been reported to cause familial or sporadic forms of human skeletal, as well as cardiac, myopathy, termed desmin-related myopathy (DRM). The impact of any of these mutations on filament assembly and integration into the cytoskeletal network of myocytes is currently not understood, despite the fact that all cause the same histopathological defect, i.e., desmin aggregation. To gain more insight into the molecular basis of this process, we investigated how mutations within the alpha-helical rod domain of desmin affect both the assembly of the recombinant protein in vitro as well as the filament-forming capacity in cDNA-transfected cells. Whereas 6 of 14 mutants assemble into seemingly normal IFs in the test tube, the other mutants interfere with the assembly process at distinct stages, i.e., tetramer formation, unit-length filament (ULF) formation, filament elongation, and IF maturation. Correspondingly, the mutants with in vitro assembly defects yield dot-like aggregates in transfected cells, whereas the mutants that form IFs constitute a seemingly normal IF cytoskeleton in the cellular context. At present, it is entirely unclear why the latter mutant proteins also lead to aggregate formation in myocytes. Hence, these findings may be a starting point to dissect the contribution of the individual subdomains for desmin pathology and, eventually, the development of therapeutic interventions.
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Affiliation(s)
- Harald Bär
- Department of Molecular Genetics, German Cancer Research Center, D-69120 Heidelberg, Germany
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Mücke N, Kirmse R, Wedig T, Leterrier JF, Kreplak L. Investigation of the morphology of intermediate filaments adsorbed to different solid supports. J Struct Biol 2005; 150:268-76. [PMID: 15890275 DOI: 10.1016/j.jsb.2005.02.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2004] [Revised: 02/17/2005] [Accepted: 02/24/2005] [Indexed: 10/25/2022]
Abstract
Morphologically, glutaraldehyde-fixed and -dried intermediate filaments (IFs) appear flexible, and with a width of 8-12 nm when observed by electron microscopy. Sometimes, the filaments are even unraveled on the carbon-coated grid and reveal a protofilamentous architecture. In this study, we have used atomic force microscopy to further investigate the morphology of IFs in a more physiological environment. First, we have imaged hydrated glutaraldehyde-fixed IFs adsorbed to a graphite support. In such conditions, human vimentin and desmin IFs appeared compact with a height of 5-8 nm and revealed either a beading repeat or a helical morphology. Second, we have analyzed the architecture of hydrated vimentin, desmin, and neurofilament IFs adsorbed to mica, graphite, and hydrophilic glass without the presence of fixative. On mica, vimentin IFs had a height of only 3-5 nm, whereas desmin IFs appeared as 8-10 nm height filaments with a helical twist. Neurofilaments were 10-12 nm in height with a pronounced 30-50 nm beading along their length. On graphite, the different IFs were either not adsorbing properly or their architecture was modified yielding, for example, broad, flattened filaments. Finally, hydrophilic glass was the surface which seemed to best preserve the architecture of the three IFs, even if, in some cases, unraveled vimentin filaments were observed on this support. These results are straightening the idea that mature IFs are dynamic polymers in vitro and that IFs can be distinguished from each others by their physicochemical properties.
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Affiliation(s)
- N Mücke
- Division Biophysics of Macromolecules, German Cancer Research Center, 69120 Heidelberg, Germany
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