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Geryk M, Charpentier F. Pathophysiological mechanisms of cardiomyopathies induced by desmin gene variants located in the C-Terminus of segment 2B. J Cell Physiol 2024; 239:e31254. [PMID: 38501553 DOI: 10.1002/jcp.31254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 02/28/2024] [Accepted: 03/05/2024] [Indexed: 03/20/2024]
Abstract
Desmin, the most abundant intermediate filament in cardiomyocytes, plays a key role in maintaining cardiomyocyte structure by interconnecting intracellular organelles, and facilitating cardiomyocyte interactions with the extracellular matrix and neighboring cardiomyocytes. As a consequence, mutations in the desmin gene (DES) can lead to desminopathies, a group of diseases characterized by variable and often severe cardiomyopathies along with skeletal muscle disorders. The basic desmin intermediate filament structure is composed of four segments separated by linkers that further assemble into dimers, tetramers and eventually unit-length filaments that compact radially to give the final form of the filament. Each step in this process is critical for proper filament formation and allow specific interactions within the cell. Mutations within the desmin gene can disrupt filament formation, as seen by aggregate formation, and thus have severe cardiac and skeletal outcomes, depending on the locus of the mutation. The focus of this review is to outline the cardiac molecular consequences of mutations located in the C-terminal part of segment 2B. This region is crucial for ensuring proper desmin filament formation and is a known hotspot for mutations that significantly impact cardiac function.
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Affiliation(s)
- Michelle Geryk
- Nantes Université, CNRS, INSERM, L'institut du thorax, Nantes, F-44000, France
| | - Flavien Charpentier
- Nantes Université, CNRS, INSERM, L'institut du thorax, Nantes, F-44000, France
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2
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Eibauer M, Weber MS, Kronenberg-Tenga R, Beales CT, Boujemaa-Paterski R, Turgay Y, Sivagurunathan S, Kraxner J, Köster S, Goldman RD, Medalia O. Vimentin filaments integrate low-complexity domains in a complex helical structure. Nat Struct Mol Biol 2024:10.1038/s41594-024-01261-2. [PMID: 38632361 DOI: 10.1038/s41594-024-01261-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 03/01/2024] [Indexed: 04/19/2024]
Abstract
Intermediate filaments (IFs) are integral components of the cytoskeleton. They provide cells with tissue-specific mechanical properties and are involved in numerous cellular processes. Due to their intricate architecture, a 3D structure of IFs has remained elusive. Here we use cryo-focused ion-beam milling, cryo-electron microscopy and tomography to obtain a 3D structure of vimentin IFs (VIFs). VIFs assemble into a modular, intertwined and flexible helical structure of 40 α-helices in cross-section, organized into five protofibrils. Surprisingly, the intrinsically disordered head domains form a fiber in the lumen of VIFs, while the intrinsically disordered tails form lateral connections between the protofibrils. Our findings demonstrate how protein domains of low sequence complexity can complement well-folded protein domains to construct a biopolymer with striking mechanical strength and stretchability.
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Affiliation(s)
- Matthias Eibauer
- Department of Biochemistry, University of Zurich, Zurich, Switzerland.
| | - Miriam S Weber
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | | | - Charlie T Beales
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | | | - Yagmur Turgay
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
- Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - Suganya Sivagurunathan
- Department of Cell and Developmental Biology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Julia Kraxner
- Institute for X-Ray Physics, University of Göttingen, Göttingen, Germany
- MDC Berlin-Buch, Max-Delbrück-Centrum für Molekulare Medizin, Berlin, Germany
| | - Sarah Köster
- Institute for X-Ray Physics, University of Göttingen, Göttingen, Germany
| | - Robert D Goldman
- Department of Cell and Developmental Biology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Ohad Medalia
- Department of Biochemistry, University of Zurich, Zurich, Switzerland.
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The N-Terminal Part of the 1A Domain of Desmin Is a Hot Spot Region for Putative Pathogenic DES Mutations Affecting Filament Assembly. Cells 2022; 11:cells11233906. [PMID: 36497166 PMCID: PMC9738904 DOI: 10.3390/cells11233906] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Accepted: 11/29/2022] [Indexed: 12/09/2022] Open
Abstract
Desmin is the major intermediate filament protein of all three muscle cell types, and connects different cell organelles and multi-protein complexes such as the cardiac desmosomes. Several pathogenic mutations in the DES gene cause different skeletal and cardiac myopathies. However, the significance of the majority of DES missense variants is currently unknown, since functional data are lacking. To determine whether desmin missense mutations within the highly conserved 1A coil domain cause a filament assembly defect, we generated a set of variants with unknown significance and systematically analyzed the filament assembly using confocal microscopy in transfected SW-13, H9c2 cells and cardiomyocytes derived from induced pluripotent stem cells. We found that mutations in the N-terminal part of the 1A coil domain affect filament assembly, leading to cytoplasmic desmin aggregation. In contrast, mutant desmin in the C-terminal part of the 1A coil domain forms filamentous structures comparable to wild-type desmin. Our findings suggest that the N-terminal part of the 1A coil domain is a hot spot for pathogenic desmin mutations, which affect desmin filament assembly. This study may have relevance for the genetic counselling of patients carrying variants in the 1A coil domain of the DES gene.
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Kuburich NA, den Hollander P, Pietz JT, Mani SA. Vimentin and cytokeratin: Good alone, bad together. Semin Cancer Biol 2022; 86:816-826. [PMID: 34953942 PMCID: PMC9213573 DOI: 10.1016/j.semcancer.2021.12.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 11/26/2021] [Accepted: 12/14/2021] [Indexed: 01/27/2023]
Abstract
The cytoskeleton plays an integral role in maintaining the integrity of epithelial cells. Epithelial cells primarily employ cytokeratin in their cytoskeleton, whereas mesenchymal cells use vimentin. During the epithelial-mesenchymal transition (EMT), cytokeratin-positive epithelial cells begin to express vimentin. EMT induces stem cell properties and drives metastasis, chemoresistance, and tumor relapse. Most studies of the functions of cytokeratin and vimentin have relied on the use of either epithelial or mesenchymal cell types. However, it is important to understand how these two cytoskeleton intermediate filaments function when co-expressed in cells undergoing EMT. Here, we discuss the individual and shared functions of cytokeratin and vimentin that coalesce during EMT and how alterations in intermediate filament expression influence carcinoma progression.
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Affiliation(s)
- Nick A Kuburich
- Department of Translational Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, United States
| | - Petra den Hollander
- Department of Translational Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, United States
| | - Jordan T Pietz
- Department of Creative Services, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, United States
| | - Sendurai A Mani
- Department of Translational Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, United States.
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Yang AW, Lin NH, Yeh TH, Snider N, Perng MD. Effects of Alexander disease-associated mutations on the assembly and organization of GFAP intermediate filaments. Mol Biol Cell 2022; 33:ar69. [PMID: 35511821 PMCID: PMC9635275 DOI: 10.1091/mbc.e22-01-0013] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Alexander disease is a primary genetic disorder of astrocytes caused by dominant mutations in the gene encoding glial fibrillary acidic protein (GFAP). How single-amino-acid changes can lead to cytoskeletal catastrophe and brain degeneration remains poorly understood. In this study, we have analyzed 14 missense mutations located in the GFAP rod domain to investigate how these mutations affect in vitro filament assembly. Whereas the internal rod mutants assembled into filaments that were shorter than those of wild type, the rod end mutants formed structures with one or more of several atypical characteristics, including short filament length, irregular width, roughness of filament surface, and filament aggregation. When transduced into primary astrocytes, GFAP mutants with in vitro assembly defects usually formed cytoplasmic aggregates, which were more resistant to biochemical extraction. The resistance of GFAP to solubilization was also observed in brain tissues of patients with Alexander disease, in which a significant proportion of insoluble GFAP were accumulated in Rosenthal fiber fractions. These findings provide clinically relevant evidence that link GFAP assembly defects to disease pathology at the tissue level and suggest that altered filament assembly and properties as a result of GFAP mutation are critical initiating factors for the pathogenesis of Alexander disease.
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Affiliation(s)
- Ai-Wen Yang
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Ni-Hsuan Lin
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Ting-Hung Yeh
- Department of Medical Science, College of Life Sciences, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Natasha Snider
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Ming-Der Perng
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu 30013, Taiwan,Department of Medical Science, College of Life Sciences, National Tsing Hua University, Hsinchu 30013, Taiwan,*Address correspondence to: Ming-Der Perng ()
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Bao Q, Zhang X, Bao P, Liang C, Guo X, Yin M, Chu M, Yan P. Genome-wide identification, characterization, and expression analysis of keratin genes (KRTs) family in yak (Bos grunniens). Gene X 2022; 818:146247. [PMID: 35085710 DOI: 10.1016/j.gene.2022.146247] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/13/2022] [Accepted: 01/21/2022] [Indexed: 11/25/2022] Open
Abstract
As the largest subgroup of intermediate filament proteins, keratins are divided into two types of subfamily. Currently, the molecular mechanism of keratins in several animals has been reported but is limited in yak. Here, 53 different kinds of keratins were identified in the yak genome, including 23 type I and 30 type II keratins. Bioinformatics analysis in this study revealed that multiple phosphorylation sites were identified among all the family members. And the subcellular localization of these proteins was predicted to be in the nucleus, cytoskeleton, and cytoplasm. All keratin family proteins were unstable and the scores of instability coefficient were higher than 40. Phylogenetic analysis showed that high consistency results of the sequence conservation and grouping were found in the genomes of yak, sheep, cattle, mouse, rat, and human. Based on the expression patterns obtained from the transcriptome data, keratin genes (KRTs) were grouped into five clusters, and results also showed that KRTs were highly activated in skin tissues during the hair cycle in yak. Among the five clusters, Cluster II contained the most KRTs, which was the main expression pattern of the yak hair follicle cycle, followed by Cluster III. These results indicated the transition period from telogen to anagen and catagen to telogen were highly dynamic in yak. Gene expression correlation analysis showed that KRTs exhibited a strong correlation (mainly positive correlation) throughout the hair follicle development cycle. And the identification of hub KRTs in specific modules related to hair follicle development in this study was performed using the Weight Gene Co-Expression Network Analysis (WGCNA). Specific modules that include KRTs were darkgreen (KRT40), darkgrey (KRT5), turquoise (KRT1, KRT2, KRT10), bisque4 (KRT4), thistle2 (KRT9, KRT39), and yellowgreen (KRT24). The interaction network showed that these genes were found to be related to the regulation of cell cycle, melanogenesis, hair follicle development, keratinocyte proliferation. Our study provides theoretical support for the study of the evolutionary relationship and molecular mechanism of keratin family in B. grunnien.
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Affiliation(s)
- Qi Bao
- Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Lanzhou 730050, China; Key Laboratory of Yak Breeding Engineering, Lanzhou 730050, China
| | - Xiaolan Zhang
- Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Lanzhou 730050, China; Key Laboratory of Yak Breeding Engineering, Lanzhou 730050, China
| | - Pengjia Bao
- Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Lanzhou 730050, China; Key Laboratory of Yak Breeding Engineering, Lanzhou 730050, China
| | - Chunnian Liang
- Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Lanzhou 730050, China; Key Laboratory of Yak Breeding Engineering, Lanzhou 730050, China
| | - Xian Guo
- Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Lanzhou 730050, China; Key Laboratory of Yak Breeding Engineering, Lanzhou 730050, China
| | - Mancai Yin
- Datong Cattle Farm in Qinghai Province, Xining 810000, China
| | - Min Chu
- Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Lanzhou 730050, China; Key Laboratory of Yak Breeding Engineering, Lanzhou 730050, China
| | - Ping Yan
- Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Lanzhou 730050, China; Key Laboratory of Yak Breeding Engineering, Lanzhou 730050, China.
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Mücke N, Wocjan T, Jacquier M, Herrmann H, Portet S. A general mathematical model for the in vitro assembly dynamics of intermediate filament proteins. Biophys J 2022; 121:1094-1104. [PMID: 35124070 PMCID: PMC8943748 DOI: 10.1016/j.bpj.2022.02.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 01/19/2022] [Accepted: 01/31/2022] [Indexed: 11/19/2022] Open
Abstract
Intermediate filament (IF) proteins assemble into highly flexible filaments that organize into complex cytoplasmic networks: keratins in all types of epithelia, vimentin in endothelia, and desmin in muscle. Since IF elongation proceeds via end-to-end annealing of unit-length filaments and successively of progressively growing filaments, it is important to know how their remarkable flexibility, i.e., their persistence length lp, influences the assembly kinetics. In fact, their lp ranges between 0.3 μm (keratin K8/K18) and 1.0 μm (vimentin and desmin), and thus is orders of magnitude lower than that of microtubules and F-actin. Here, we present a unique mathematical model, which implements the semiflexible nature of the three IF types based on published semiflexible polymers theories and depends on a single free parameter k0. Calibrating this model to filament mean length dynamics of the three proteins, we demonstrate that the persistence length is indeed essential to accurately describe their assembly kinetics. Furthermore, we reveal that the difference in flexibility alone does not explain the significantly faster assembly rate of keratin filaments compared with that of vimentin. Likewise, desmin assembles approximately six times faster than vimentin, even though both their filaments exhibit the same lp value. These data strongly indicate that differences in their individual amino acid sequences significantly impact the assembly rates. Nevertheless, using a single k0 value for each of these three key representatives of the IF protein family, our advanced model does accurately describe the length distribution and mean length dynamics and provides effective filament assembly rates. It thus provides a tool for future investigations on the impact of posttranslational modifications or amino acid changes of IF proteins on assembly kinetics. This is an important issue, as the discovery of mutations in IF genes causing severe human disease, particularly for desmin and keratins, is steadily increasing.
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Affiliation(s)
- Norbert Mücke
- Chromatin Networks, German Cancer Research Center (DKFZ), Heidelberg, Germany; Biophysics of Macromolecules, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Tomasz Wocjan
- Biophysics of Macromolecules, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | | | - Harald Herrmann
- Institute of Neuropathology, University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Stéphanie Portet
- Department of Mathematics, University of Manitoba, Winnipeg, Manitoba, Canada.
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Oka H, Nakau K, Imanishi R, Furukawa T, Tanabe Y, Hirono K, Hata Y, Nishida N, Azuma H. A Case Report of a Rare Heterozygous Variant in the Desmin Gene Associated With Hypertrophic Cardiomyopathy and Complete Atrioventricular Block. CJC Open 2021; 3:1195-1198. [PMID: 34712946 PMCID: PMC8531214 DOI: 10.1016/j.cjco.2021.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 05/04/2021] [Indexed: 11/18/2022] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is the primary cause of sudden cardiac death in children and adolescents. Patients with HCM frequently have ventricular tachycardia and ventricular fibrillation, although complete atrioventricular block (CAVB) is very rare. We report a case of HCM with CAVB in an 8-year-old girl who underwent transvenous implantable cardioverter-defibrillator placement after resuscitation. In this patient, we identified a de novo heterozygous missense variant, Arg406Trp (c.1216C > T), in the desmin (DES) gene. Pathogenic variants in the DES gene result in cardiomyopathy, conduction disorders, and skeletal muscle weakness. This recently identified variant may cause HCM with CAVB.
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Affiliation(s)
- Hideharu Oka
- Department of Pediatrics, Asahikawa Medical University, Asahikawa, Japan
- Corresponding author: Dr Hideharu Oka, Department of Pediatrics, Asahikawa Medical University, 2-1-1-1, Midorigaoka-Higashi, Asahikawa, 0788510, Japan. Tel.: +81-16668-2481; fax: +81-16668-2489.
| | - Kouichi Nakau
- Department of Pediatrics, Asahikawa Medical University, Asahikawa, Japan
| | - Rina Imanishi
- Department of Pediatrics, Asahikawa Medical University, Asahikawa, Japan
| | - Takuo Furukawa
- Department of Pediatrics, Asahikawa City Hospital, Asahikawa, Japan
| | - Yasuko Tanabe
- Department of Cardiology, Asahikawa Medical University, Asahikawa, Japan
| | - Keiichi Hirono
- Department of Pediatrics, Faculty of Medicine, University of Toyama, Toyama, Japan
| | - Yukiko Hata
- Department of Legal Medicine, Faculty of Medicine, University of Toyama, Toyama, Japan
| | - Naoki Nishida
- Department of Legal Medicine, Faculty of Medicine, University of Toyama, Toyama, Japan
| | - Hiroshi Azuma
- Department of Pediatrics, Asahikawa Medical University, Asahikawa, Japan
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Shelly S, Talha N, Pereira NL, Engel AG, Johnson JN, Selcen D. Expanding Spectrum of Desmin-Related Myopathy, Long-term Follow-up, and Cardiac Transplantation. Neurology 2021; 97:e1150-e1158. [PMID: 34315782 DOI: 10.1212/wnl.0000000000012542] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 06/22/2021] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE We aimed to determine the genetic and clinical phenotypes of desmin-related myopathy patients and long-term outcomes after cardiac transplant. METHODS Retrospective review of cardiac and neurological manifestations of genetically confirmed desmin-related myopathy patients (Jan 1st, 1999-Jan 1st, 2020). RESULTS Twenty-five patients in 20 different families were recognized. Median age at onset of symptoms was 20 years (range: 4-50), median follow-up time of 36 months (range: 1-156). Twelve patients initially presented with skeletal muscle involvement and 13 with cardiac disease. Sixteen patients had both cardiac and skeletal muscle involvement. Clinically muscle weakness distribution was distal (n=11), proximal (n=4) or both (n=7) of 22 patients. Skeletal muscle biopsy from patients with missense and splice site variants (n=12) showed abnormal fibers containing amorphous material in Gomori trichrome stained sections. Patients with cardiac involvement had atrioventricular conduction abnormalities or cardiomyopathy. The most common ECG abnormality was complete AV block in 11 patients all of whom required a permanent pacemaker at a median age of 25 years (range: 16-48). Sudden cardiac death resulting in implantable cardioverter defibrillator (ICD) shocks or resuscitation were reported in 3 patients, a total of 5 patients had ICDs. Orthotopic cardiac transplantation was performed in 3 patients at 20, 35 and 39 years of age. CONCLUSIONS Pathogenic variants in desmin can lead to varied neurological and cardiac phenotypes beginning at a young age. Two-thirds of the patients have both neurologic and cardiac symptoms usually starting in the third decade. Heart transplant was tolerated with improved cardiac function and quality of life.
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Affiliation(s)
| | - Niaz Talha
- Department of Pediatric and Adolescent Medicine, Rochester, MN
| | | | | | | | - Duygu Selcen
- Department of Neurology, Mayo Clinic, Rochester, MN
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Lin NH, Yang AW, Chang CH, Perng MD. Elevated GFAP isoform expression promotes protein aggregation and compromises astrocyte function. FASEB J 2021; 35:e21614. [PMID: 33908669 DOI: 10.1096/fj.202100087r] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 03/19/2021] [Accepted: 04/06/2021] [Indexed: 01/22/2023]
Abstract
Alexander disease (AxD) caused by mutations in the coding region of GFAP is a neurodegenerative disease characterized by astrocyte dysfunction, GFAP aggregation, and Rosenthal fiber accumulation. Although how GFAP mutations cause disease is not fully understood, Rosenthal fibers could be induced by forced overexpression of human GFAP and this could be lethal in mice implicate that an increase in GFAP levels is central to AxD pathogenesis. Our recent studies demonstrated that intronic GFAP mutations cause disease by altering GFAP splicing, suggesting that an increase in GFAP isoform expression could lead to protein aggregation and astrocyte dysfunction that typify AxD. Here we test this hypothesis by establishing primary astrocyte cultures from transgenic mice overexpressing human GFAP. We found that GFAP-δ and GFAP-κ were disproportionately increased in transgenic astrocytes and both were enriched in Rosenthal fibers of human AxD brains. In vitro assembly studies showed that while the major isoform GFAP-α self-assembled into typical 10-nm filaments, minor isoforms including GFAP-δ, -κ, and -λ were assembly-compromised and aggregation prone. Lentiviral transduction showed that expression of these minor GFAP isoforms decreased filament solubility and increased GFAP stability, leading to the formation of Rosenthal fibers-like aggregates that also disrupted the endogenous intermediate filament networks. The aggregate-bearing astrocytes lost their normal morphology and glutamate buffering capacity, which had a toxic effect on neighboring neurons. In conclusion, our findings provide evidence that links elevated GFAP isoform expression with GFAP aggregation and impaired glutamate transport, and suggest a potential non-cell-autonomous mechanism underlying neurodegeneration through astrocyte dysfunction.
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Affiliation(s)
- Ni-Hsuan Lin
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, Taiwan
| | - Ai-Wen Yang
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, Taiwan
| | - Chih-Hsuan Chang
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, Taiwan
| | - Ming-Der Perng
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, Taiwan.,Department of Medical Science, College of Life Sciences, National Tsing Hua University, Hsinchu, Taiwan
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Separation of Coiled-Coil Structures in Lamin A/C Is Required for the Elongation of the Filament. Cells 2020; 10:cells10010055. [PMID: 33396475 PMCID: PMC7824274 DOI: 10.3390/cells10010055] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 12/28/2020] [Accepted: 12/29/2020] [Indexed: 02/07/2023] Open
Abstract
Intermediate filaments (IFs) commonly have structural elements of a central α-helical coiled-coil domain consisting of coil 1a, coil 1b, coil 2, and their flanking linkers. Recently, the crystal structure of a long lamin A/C fragment was determined and showed detailed features of a tetrameric unit. The structure further suggested a new binding mode between tetramers, designated eA22, where a parallel overlap of coil 1a and coil 2 is the critical interaction. This study investigated the biochemical effects of genetic mutations causing human diseases, focusing on the eA22 interaction. The mutant proteins exhibited either weakened or augmented interactions between coil 1a and coil 2. The ensuing biochemical results indicated that the interaction requires the separation of the coiled-coils in the N-terminal of coil 1a and the C-terminal of coil 2, coupled with the structural transition in the central α-helical rod domain. This study provides insight into the role of coil 1a as a molecular regulator in the elongation of IF proteins.
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12
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Fischer B, Dittmann S, Brodehl A, Unger A, Stallmeyer B, Paul M, Seebohm G, Kayser A, Peischard S, Linke WA, Milting H, Schulze-Bahr E. Functional characterization of novel alpha-helical rod domain desmin (DES) pathogenic variants associated with dilated cardiomyopathy, atrioventricular block and a risk for sudden cardiac death. Int J Cardiol 2020; 329:167-174. [PMID: 33373648 DOI: 10.1016/j.ijcard.2020.12.050] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 12/02/2020] [Accepted: 12/07/2020] [Indexed: 11/24/2022]
Abstract
BACKGROUND Desmin is the major intermediate filament (IF) protein in human heart and skeletal muscle. So-called 'desminopathies' are disorders due to pathogenic variants in the DES gene and are associated with skeletal myopathies and/or various types of cardiomyopathies. So far, only a limited number of DES pathogenic variants have been identified and functionally characterized. METHODS AND RESULTS Using a Sanger- and next generation sequencing (NGS) approach in patients with various types of cardiomyopathies, we identified two novel, non-synonymous missense DES variants: p.(Ile402Thr) and p.(Glu410Lys). Mutation carriers developed dilated (DCM) or arrhythmogenic cardiomyopathy (ACM), and cardiac conduction disease, leading to spare out the exercise-induced polymorphic ventricular tachycardia; we moved this variant to data in brief. To investigate the functional impact of these four DES variants, transfection experiments using SW-13 and H9c2 cells with native and mutant desmin were performed and filament assembly was analyzed by confocal microscopy. The DES_p.(Ile402Thr) and DES_p.(Glu410Lys) cells showed filament assembly defects forming cytoplasmic desmin aggregates. Furthermore, immunohistochemical and ultrastructural analysis of myocardial tissue from mutation carriers with the DES_p.(Glu410Lys) pathogenic variant supported the in vitro results. CONCLUSIONS Our in vitro results supported the classification of DES_p.(Ile402Thr) and DES_p.(Glu410Lys) as novel pathogenic variants and demonstrated that the cardiac phenotypes associated with DES variants are diverse and cell culture experiments improve in silico analysis and genetic counseling because the pathogenicity of a variant can be clarified.
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Affiliation(s)
- Björn Fischer
- Institute for Genetics of Heart Disease (IfGH), Department of Cardiovascular Medicine, University Hospital Muenster, Muenster, Germany
| | - Sven Dittmann
- Institute for Genetics of Heart Disease (IfGH), Department of Cardiovascular Medicine, University Hospital Muenster, Muenster, Germany.
| | - Andreas Brodehl
- Erich and Hanna Klessmann Institute, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Bad Oeynhausen, Germany
| | - Andreas Unger
- Institute of Physiology II, University of Muenster, Germany
| | - Birgit Stallmeyer
- Institute for Genetics of Heart Disease (IfGH), Department of Cardiovascular Medicine, University Hospital Muenster, Muenster, Germany
| | - Matthias Paul
- Department of Cardiology I, University Hospital Muenster, Muenster, Germany
| | - Guiscard Seebohm
- Institute for Genetics of Heart Disease (IfGH), Department of Cardiovascular Medicine, University Hospital Muenster, Muenster, Germany
| | - Anne Kayser
- Institute for Genetics of Heart Disease (IfGH), Department of Cardiovascular Medicine, University Hospital Muenster, Muenster, Germany
| | - Stefan Peischard
- Institute for Genetics of Heart Disease (IfGH), Department of Cardiovascular Medicine, University Hospital Muenster, Muenster, Germany
| | | | - Hendrik Milting
- Erich and Hanna Klessmann Institute, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Bad Oeynhausen, Germany
| | - Eric Schulze-Bahr
- Institute for Genetics of Heart Disease (IfGH), Department of Cardiovascular Medicine, University Hospital Muenster, Muenster, Germany
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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: 21] [Impact Index Per Article: 5.3] [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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14
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Fu MH, Chang YY, Lin NH, Yang AW, Chang CC, Liu JS, Peng CH, Wu KLH, Perng MD, Lan MY. Recessively-Inherited Adult-Onset Alexander Disease Caused by a Homozygous Mutation in the GFAP Gene. Mov Disord 2020; 35:1662-1667. [PMID: 32374915 DOI: 10.1002/mds.28099] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 04/01/2020] [Accepted: 04/09/2020] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND Alexander disease (AxD) is an autosomal-dominant leukodystrophy caused by heterozygous mutations in the glial fibrillary acidic protein (GFAP) gene. OBJECTIVES The objective of this report is to characterize the clinical phenotype and identify the genetic mutation associated with adult-onset AxD. METHODS A man presented with progressive unsteadiness since age 16. Magnetic resonance imaging findings revealed characteristic features of AxD. The GFAP gene was screened, and a candidate variant was functionally tested to evaluate causality. RESULTS A homozygous c.197G > A (p.Arg66Gln) mutation was found in the proband, and his asymptomatic parents were heterozygous for the same mutation. This mutation affected GFAP solubility and promoted filament aggregation. The presence of the wild-type protein rescued mutational effects, consistent with the recessive nature of this mutation. CONCLUSIONS This study is the first report of AxD caused by a homozygous mutation in GFAP. The clinical implication is while examining patients with characteristic features on suspicion of AxD, GFAP screening is recommended even without a supportive family history. © 2020 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Mu-Hui Fu
- Department of Neurology, Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Yung-Yee Chang
- Department of Neurology, Chang Gung University College of Medicine, Kaohsiung, Taiwan.,Center for Parkinson's Disease, Kaohsiung Chang Gung Memorial Hospital, and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Ni-Hsuan Lin
- Institute of Molecular Medicine, College of Life Sciences, National Tsing Hua University, Hsinchu, Taiwan
| | - Ai-Wen Yang
- Institute of Molecular Medicine, College of Life Sciences, National Tsing Hua University, Hsinchu, Taiwan.,Department of Medical Science, College of Life Sciences, National Tsing Hua University, Hsinchu, Taiwan
| | - Chiung-Chih Chang
- Department of Neurology, Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Jia-Shou Liu
- Department of Neurology, Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Cheng-Huei Peng
- Department of Neurology, Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Kay L H Wu
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan.,Department of Senior Citizen Services, National Tainan Institute of Nursing, Tainan, Taiwan
| | - Ming-Der Perng
- Institute of Molecular Medicine, College of Life Sciences, National Tsing Hua University, Hsinchu, Taiwan.,Department of Medical Science, College of Life Sciences, National Tsing Hua University, Hsinchu, Taiwan
| | - Min-Yu Lan
- Department of Neurology, Chang Gung University College of Medicine, Kaohsiung, Taiwan.,Center for Parkinson's Disease, Kaohsiung Chang Gung Memorial Hospital, and Chang Gung University College of Medicine, Kaohsiung, Taiwan
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15
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Gae DD, Budamagunta MS, Hess JF, McCarrick RM, Lorigan GA, FitzGerald PG, Voss JC. Completion of the Vimentin Rod Domain Structure Using Experimental Restraints: A New Tool for Exploring Intermediate Filament Assembly and Mutations. Structure 2019; 27:1547-1560.e4. [PMID: 31402219 PMCID: PMC6774864 DOI: 10.1016/j.str.2019.07.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 05/23/2019] [Accepted: 07/22/2019] [Indexed: 11/28/2022]
Abstract
Electron paramagnetic resonance (EPR) spectroscopy of full-length vimentin and X-ray crystallography of vimentin peptides has provided concordant structural data for nearly the entire central rod domain of the protein. In this report, we use a combination of EPR spectroscopy and molecular modeling to determine the structure and dynamics of the missing region and unite the separate elements into a single structure. Validation of the linker 1-2 (L1-2) modeling approach is demonstrated by the close correlation between EPR and X-ray data in the previously solved regions. Importantly, molecular dynamic (MD) simulation of the constructed model agrees with spin label motion as determined by EPR. Furthermore, MD simulation shows L1-2 heterogeneity, with a concerted switching of states among the dimer chains. These data provide the first ever experimentally driven model of a complete intermediate filament rod domain, providing research tools for further modeling and assembly studies.
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Affiliation(s)
- David D Gae
- Department of Surgery, School of Medicine, University of California San Francisco, San Francisco, CA 94118, USA
| | - Madhu S Budamagunta
- Department of Biochemistry & Molecular Medicine, School of Medicine, University of California Davis, Davis, CA 95616, USA
| | - John F Hess
- Department of Cell Biology and Human Anatomy, School of Medicine, University of California Davis, Davis, CA 95616, USA
| | - Robert M McCarrick
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Paul G FitzGerald
- Department of Cell Biology and Human Anatomy, School of Medicine, University of California Davis, Davis, CA 95616, USA.
| | - John C Voss
- Department of Biochemistry & Molecular Medicine, School of Medicine, University of California Davis, Davis, CA 95616, USA.
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16
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Brodehl A, Gaertner-Rommel A, Milting H. Molecular insights into cardiomyopathies associated with desmin (DES) mutations. Biophys Rev 2018; 10:983-1006. [PMID: 29926427 DOI: 10.1007/s12551-018-0429-0] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 05/22/2018] [Indexed: 12/15/2022] Open
Abstract
Increasing usage of next-generation sequencing techniques pushed during the last decade cardiogenetic diagnostics leading to the identification of a huge number of genetic variants in about 170 genes associated with cardiomyopathies, channelopathies, or syndromes with cardiac involvement. Because of the biochemical and cellular complexity, it is challenging to understand the clinical meaning or even the relevant pathomechanisms of the majority of genetic sequence variants. However, detailed knowledge about the associated molecular pathomechanism is essential for the development of efficient therapeutic strategies in future and genetic counseling. Mutations in DES, encoding the muscle-specific intermediate filament protein desmin, have been identified in different kinds of cardiac and skeletal myopathies. Here, we review the functions of desmin in health and disease with a focus on cardiomyopathies. In addition, we will summarize the genetic and clinical literature about DES mutations and will explain relevant cell and animal models. Moreover, we discuss upcoming perspectives and consequences of novel experimental approaches like genome editing technology, which might open a novel research field contributing to the development of efficient and mutation-specific treatment options.
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Affiliation(s)
- Andreas Brodehl
- Erich and Hanna Klessmann Institute for Cardiovascular Research & Development, Heart and Diabetes Centre NRW, Ruhr-University Bochum, Georgstrasse 11, 32545, Bad Oeynhausen, Germany.
| | - Anna Gaertner-Rommel
- Erich and Hanna Klessmann Institute for Cardiovascular Research & Development, Heart and Diabetes Centre NRW, Ruhr-University Bochum, Georgstrasse 11, 32545, Bad Oeynhausen, Germany
| | - Hendrik Milting
- Erich and Hanna Klessmann Institute for Cardiovascular Research & Development, Heart and Diabetes Centre NRW, Ruhr-University Bochum, Georgstrasse 11, 32545, Bad Oeynhausen, Germany.
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17
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Deng Y, Xia D, Wang L, Li M, Li W. Identification of a novel missense KRT86 mutation in a Chinese family with monilethrix. J Dermatol 2018; 45:e298-e300. [PMID: 29701253 DOI: 10.1111/1346-8138.14339] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Ying Deng
- National Office for Maternal and Child Health Surveillance of China, Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, China.,Laboratory of Molecular Epidemiology for Birth Defect, West China Institute of Women and Children's Health, Sichuan University, Chengdu, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Dengmei Xia
- Department of Dermatology, Southwest Medical University Affiliated Hospital, Luzhou, China
| | - Lian Wang
- Department of Dermatology, The West China Hospital, Sichuan University, Chengdu, China
| | - Mengmeng Li
- Department of Dermatology, The West China Hospital, Sichuan University, Chengdu, China
| | - Wei Li
- Department of Dermatology, The West China Hospital, Sichuan University, Chengdu, China
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18
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Premchandar A, Mücke N, Poznański J, Wedig T, Kaus-Drobek M, Herrmann H, Dadlez M. Structural Dynamics of the Vimentin Coiled-coil Contact Regions Involved in Filament Assembly as Revealed by Hydrogen-Deuterium Exchange. J Biol Chem 2016; 291:24931-24950. [PMID: 27694444 PMCID: PMC5122765 DOI: 10.1074/jbc.m116.748145] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 09/26/2016] [Indexed: 01/07/2023] Open
Abstract
Intermediate filaments (IF) are major constituents of the cytoskeleton of metazoan cells. They are not only responsible for the mechanical properties but also for various physiological activities in different cells and tissues. The building blocks of IFs are extended coiled-coil-forming proteins exhibiting a characteristic central α-helical domain ("rod"). The fundamental principles of the filament assembly mechanism and the network formation have been widely elucidated for the cytoplasmic IF protein vimentin. Also, a comprehensive structural model for the tetrameric complex of vimentin has been obtained by X-ray crystallography in combination with various biochemical and biophysical techniques. To extend these static data and to investigate the dynamic properties of the full-length proteins in solution during the various assembly steps, we analyzed the patterns of hydrogen-deuterium exchange in vimentin and in four variants carrying point mutations in the IF consensus motifs present at either end of the α-helical rod that cause an assembly arrest at the unit-length filament (ULF) stage. The results yielded unique insights into the structural properties of subdomains within the full-length vimentin, in particular in regions of contact in α-helical and linker segments that stabilize different oligomeric forms such as tetramers, ULFs, and mature filaments. Moreover, hydrogen-deuterium exchange analysis of the point-mutated variants directly demonstrated the active role of the IF consensus motifs in the oligomerization mechanism of tetramers during ULF formation. Ultimately, using molecular dynamics simulation procedures, we provide a structural model for the subdomain-mediated tetramer/tetramer interaction via "cross-coiling" as the first step of the assembly process.
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Affiliation(s)
- Aiswarya Premchandar
- From the Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5A, 02-106 Warsaw, Poland
| | | | - Jarosław Poznański
- From the Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5A, 02-106 Warsaw, Poland
| | | | - Magdalena Kaus-Drobek
- From the Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5A, 02-106 Warsaw, Poland
| | - Harald Herrmann
- Division of Molecular Genetics, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany, and
- the Institute of Neuropathology, University Hospital Erlangen, D-91054 Erlangen, Germany
| | - Michał Dadlez
- From the Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5A, 02-106 Warsaw, Poland,
- the Institute of Genetics and Biotechnology, Biology Department, University of Warsaw, Miecznikowa 3, 02-106 Warsaw, Poland
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19
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Abstract
Proteins of the intermediate filament (IF) supergene family are ubiquitous structural components that comprise, in a cell type-specific manner, the cytoskeleton proper in animal tissues. All IF proteins show a distinctly organized, extended α-helical conformation prone to form two-stranded coiled coils, which are the basic building blocks of these highly flexible, stress-resistant cytoskeletal filaments. IF proteins are highly charged, thus representing versatile polyampholytes with multiple functions. Taking vimentin, keratins, and the nuclear lamins as our prime examples, we present an overview of their molecular and structural parameters. These, in turn, document the ability of IF proteins to form distinct, highly diverse supramolecular assemblies and biomaterials found, for example, at the inner nuclear membrane, throughout the cytoplasm, and in highly complex extracellular appendages, such as hair and nails, of vertebrate organisms. Ultimately, our aim is to set the stage for a more rational understanding of the immediate effects that missense mutations in IF genes have on cellular functions and for their far-reaching impact on the development of the numerous IF diseases caused by them.
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Affiliation(s)
- Harald Herrmann
- Functional Architecture of the Cell (B065), German Cancer Research Center (DKFZ), D-69120 Heidelberg, Germany, and Institute of Neuropathology, University Hospital Erlangen, D-91054 Erlangen, Germany
| | - Ueli Aebi
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland
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20
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Charrier EE, Asnacios A, Milloud R, De Mets R, Balland M, Delort F, Cardoso O, Vicart P, Batonnet-Pichon S, Hénon S. Desmin Mutation in the C-Terminal Domain Impairs Traction Force Generation in Myoblasts. Biophys J 2016; 110:470-480. [PMID: 26789769 DOI: 10.1016/j.bpj.2015.11.3518] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 11/06/2015] [Accepted: 11/23/2015] [Indexed: 02/08/2023] Open
Abstract
The cytoskeleton plays a key role in the ability of cells to both resist mechanical stress and generate force, but the precise involvement of intermediate filaments in these processes remains unclear. We focus here on desmin, a type III intermediate filament, which is specifically expressed in muscle cells and serves as a skeletal muscle differentiation marker. By using several complementary experimental techniques, we have investigated the impact of overexpressing desmin and expressing a mutant desmin on the passive and active mechanical properties of C2C12 myoblasts. We first show that the overexpression of wild-type-desmin increases the overall rigidity of the cells, whereas the expression of a mutated E413K desmin does not. This mutation in the desmin gene is one of those leading to desminopathies, a subgroup of myopathies associated with progressive muscular weakness that are characterized by the presence of desmin aggregates and a disorganization of sarcomeres. We show that the expression of this mutant desmin in C2C12 myoblasts induces desmin network disorganization, desmin aggregate formation, and a small decrease in the number and total length of stress fibers. We finally demonstrate that expression of the E413K mutant desmin also alters the traction forces generation of single myoblasts lacking organized sarcomeres.
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Affiliation(s)
- Elisabeth E Charrier
- Unité de Biologie Fonctionnelle et Adaptative, Université Paris Diderot, Sorbonne Paris Cité, CNRS, UMR 8251, Paris, France; Matière et Systèmes Complexes, Université Paris Diderot, Sorbonne Paris Cité, CNRS, UMR 7057, Paris, France
| | - Atef Asnacios
- Matière et Systèmes Complexes, Université Paris Diderot, Sorbonne Paris Cité, CNRS, UMR 7057, Paris, France
| | - Rachel Milloud
- LIPhy Université Grenoble 1, CNRS, UMR 5588, Grenoble, France
| | - Richard De Mets
- LIPhy Université Grenoble 1, CNRS, UMR 5588, Grenoble, France
| | - Martial Balland
- LIPhy Université Grenoble 1, CNRS, UMR 5588, Grenoble, France
| | - Florence Delort
- Unité de Biologie Fonctionnelle et Adaptative, Université Paris Diderot, Sorbonne Paris Cité, CNRS, UMR 8251, Paris, France
| | - Olivier Cardoso
- Matière et Systèmes Complexes, Université Paris Diderot, Sorbonne Paris Cité, CNRS, UMR 7057, Paris, France
| | - Patrick Vicart
- Unité de Biologie Fonctionnelle et Adaptative, Université Paris Diderot, Sorbonne Paris Cité, CNRS, UMR 8251, Paris, France
| | - Sabrina Batonnet-Pichon
- Unité de Biologie Fonctionnelle et Adaptative, Université Paris Diderot, Sorbonne Paris Cité, CNRS, UMR 8251, Paris, France
| | - Sylvie Hénon
- Matière et Systèmes Complexes, Université Paris Diderot, Sorbonne Paris Cité, CNRS, UMR 7057, Paris, France.
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21
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Epithelial cell migration requires the interaction between the vimentin and keratin intermediate filaments. Sci Rep 2016; 6:24389. [PMID: 27072292 PMCID: PMC4829867 DOI: 10.1038/srep24389] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 03/29/2016] [Indexed: 11/08/2022] Open
Abstract
Epithelial migration plays a central role in development, wound repair and tumor metastasis, but the role of intermediate filament in this important event is unknown. We showed recently that vimentin coexists in the same cell with keratin-KRT14 at the leading edge of the migrating epidermal cells, and knockdown of vimentin impaired colony growth. Here we demonstrate that vimentin co-localizes and co-immunoprecipitates with keratin-KRT14, and mutations in the -YRKLLEGEE- sequence of vimentin significantly reduced migration of the keratinocytes. Our data demonstrates that keratinocyte migration requires the interaction between vimentin and keratins at the -YRKLLEGEE- sequence at the helical 2B domain of vimentin. These findings have broad implications for understanding the roles of vimentin intermediate filaments in normal and neoplastic epithelial cells.
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22
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Hamed E, Ma D, Keten S. Effect of Polymer Conjugation Site on Stability and Self-Assembly of Coiled Coils. BIONANOSCIENCE 2015. [DOI: 10.1007/s12668-015-0172-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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23
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Hess JF, Budamagunta MS, Aziz A, FitzGerald PG, Voss JC. Electron paramagnetic resonance analysis of the vimentin tail domain reveals points of order in a largely disordered region and conformational adaptation upon filament assembly. Protein Sci 2014; 22:47-55. [PMID: 23109052 DOI: 10.1002/pro.2182] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 10/15/2012] [Indexed: 01/27/2023]
Abstract
Very little data have been reported that describe the structure of the tail domain of any cytoplasmic intermediate filament (IF) protein. We report here the results of studies using site directed spin labeling and electron paramagnetic resonance (SDSL-EPR) to explore the structure and dynamics of the tail domain of human vimentin in tetramers (protofilaments) and filaments. The data demonstrate that in contrast to the vimentin head and rod domains, the tail domains are not closely apposed in protofilaments. However, upon assembly into intact IFs, several sites, including positions 445, 446, 451, and 452, the conserved "beta-site," become closely apposed, indicating dynamic changes in tail domain structure that accompany filament elongation. No evidence is seen for coiled-coil structure within the region studied, in either protofilaments or assembled filaments. EPR analysis also establishes that more than half of the tail domain is very flexible in both the assembly intermediate and the intact IF. However, by positioning the spin label at distinct sites, EPR is able to identify both the rod proximal region and sites flanking the beta-site motif as rigid locations within the tail. The rod proximal region is well assembled at the tetramer stage with only slight changes occurring during filament elongation. In contrast, at the beta site, the polypeptide backbone transitions from flexible in the assembly intermediate to much more rigid in the intact IF. These data support a model in which the distal tail domain structure undergoes significant conformational change during filament elongation and final assembly.
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Affiliation(s)
- John F Hess
- Department of Cell Biology and Human Anatomy, University of California, Davis, California 95616, USA
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24
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Sequence-resolved free energy profiles of stress-bearing vimentin intermediate filaments. Proc Natl Acad Sci U S A 2014; 111:11359-64. [PMID: 25049381 DOI: 10.1073/pnas.1403122111] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Intermediate filaments (IFs) are key to the mechanical strength of metazoan cells. Their basic building blocks are dimeric coiled coils mediating hierarchical assembly of the full-length filaments. Here we use single-molecule force spectroscopy by optical tweezers to assess the folding and stability of coil 2B of the model IF protein vimentin. The coiled coil was unzipped from its N and C termini. When pulling from the C terminus, we observed that the coiled coil was resistant to force owing to the high stability of the C-terminal region. Pulling from the N terminus revealed that the N-terminal half is considerably less stable. The mechanical pulling assay is a unique tool to study and control seed formation and structure propagation of the coiled coil. We then used rigorous theory-based deconvolution for a model-free extraction of the energy landscape and local stability profiles. The data obtained from the two distinct pulling directions complement each other and reveal a tripartite stability of the coiled coil: a labile N-terminal half, followed by a medium stability section and a highly stable region at the far C-terminal end. The different stability regions provide important insight into the mechanics of IF assembly.
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25
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Banerjee S, Wu Q, Yu P, Qi M, Li C. In silico analysis of all point mutations on the 2B domain of K5/K14 causing epidermolysis bullosa simplex: a genotype–phenotype correlation. MOLECULAR BIOSYSTEMS 2014; 10:2567-77. [DOI: 10.1039/c4mb00138a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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26
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Caspase cleavage of GFAP produces an assembly-compromised proteolytic fragment that promotes filament aggregation. ASN Neuro 2013; 5:e00125. [PMID: 24102621 PMCID: PMC3833455 DOI: 10.1042/an20130032] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
IF (intermediate filament) proteins can be cleaved by caspases to generate proapoptotic fragments as shown for desmin. These fragments can also cause filament aggregation. The hypothesis is that disease-causing mutations in IF proteins and their subsequent characteristic histopathological aggregates could involve caspases. GFAP (glial fibrillary acidic protein), a closely related IF protein expressed mainly in astrocytes, is also a putative caspase substrate. Mutations in GFAP cause AxD (Alexander disease). The overexpression of wild-type or mutant GFAP promotes cytoplasmic aggregate formation, with caspase activation and GFAP proteolysis. In this study, we report that GFAP is cleaved specifically by caspase 6 at VELD²²⁵ in its L12 linker domain in vitro. Caspase cleavage of GFAP at Asp²²⁵ produces two major cleavage products. While the C-GFAP (C-terminal GFAP) is unable to assemble into filaments, the N-GFAP (N-terminal GFAP) forms filamentous structures that are variable in width and prone to aggregation. The effect of N-GFAP is dominant, thus affecting normal filament assembly in a way that promotes filament aggregation. Transient transfection of N-GFAP into a human astrocytoma cell line induces the formation of cytoplasmic aggregates, which also disrupt the endogenous GFAP networks. In addition, we generated a neo-epitope antibody that recognizes caspase-cleaved but not the intact GFAP. Using this antibody, we demonstrate the presence of the caspase-generated GFAP fragment in transfected cells expressing a disease-causing mutant GFAP and in two mouse models of AxD. These findings suggest that caspase-mediated GFAP proteolysis may be a common event in the context of both the GFAP mutation and excess.
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27
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Parry DAD. Fifty years of fibrous protein research: a personal retrospective. J Struct Biol 2013; 186:320-34. [PMID: 24148884 DOI: 10.1016/j.jsb.2013.10.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 10/09/2013] [Accepted: 10/11/2013] [Indexed: 02/02/2023]
Abstract
As a result of X-ray fiber diffraction studies on fibrous proteins and crystallographic data on fragments derived from them, new experimental techniques across the biophysical and biochemical spectra, sophisticated computer modeling and refinement procedures, widespread use of bioinformatics and improved specimen preparative procedures the structures of many fibrous proteins have now been determined to at least low resolution. In so doing these structures have yielded insight into the relationship that exists between sequence and conformation and this, in turn, has led to improved methodologies for predicting structure from sequence data alone. In this personal retrospective a selection of progress made during the past 50years is discussed in terms of events to which the author has made some contribution.
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Affiliation(s)
- David A D Parry
- Institute of Fundamental Sciences, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand.
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28
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Guharoy M, Szabo B, Martos SC, Kosol S, Tompa P. Intrinsic Structural Disorder in Cytoskeletal Proteins. Cytoskeleton (Hoboken) 2013; 70:550-71. [DOI: 10.1002/cm.21118] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 05/26/2013] [Accepted: 05/29/2013] [Indexed: 12/11/2022]
Affiliation(s)
- Mainak Guharoy
- VIB Department of Structural Biology; Vrije Universiteit Brussel; Brussels Belgium
| | - Beata Szabo
- Institute of Enzymology; Research Centre for Natural Sciences, Hungarian Academy of Sciences; Budapest Hungary
| | | | - Simone Kosol
- VIB Department of Structural Biology; Vrije Universiteit Brussel; Brussels Belgium
| | - Peter Tompa
- VIB Department of Structural Biology; Vrije Universiteit Brussel; Brussels Belgium
- Institute of Enzymology; Research Centre for Natural Sciences, Hungarian Academy of Sciences; Budapest Hungary
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Joanne P, Chourbagi O, Hourdé C, Ferry A, Butler-Browne G, Vicart P, Dumonceaux J, Agbulut O. Viral-mediated expression of desmin mutants to create mouse models of myofibrillar myopathy. Skelet Muscle 2013; 3:4. [PMID: 23425003 PMCID: PMC3599656 DOI: 10.1186/2044-5040-3-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 01/28/2013] [Indexed: 12/26/2022] Open
Abstract
Background The clinical features of myofibrillar myopathies display a wide phenotypic heterogeneity. To this date, no studies have evaluated this parameter due to the absence of pertinent animal models. By studying two mutants of desmin, which induce subtle phenotypic differences in patients, we address this issue using an animal model based on the use of adeno-associated virus (AAV) vectors carrying mutated desmin cDNA. Methods After preparation of the vectors, they were injected directly into the tibialis anterior muscles of C57BL/6 mice to allow expression of wild-type (WT) or mutated (R406W or E413K) desmin. Measurements of maximal force were carried out on the muscle in situ and then the injected muscles were analyzed to determine the structural consequences of the desmin mutations on muscle structure (microscopic observations, histology and immunohistochemistry). Results Injection of AAV carrying WT desmin results in the expression of exogenous desmin in 98% of the muscle fibers without any pathological or functional perturbations. Exogenous WT and endogenous desmin are co-localized and no differences were observed compared to non-injected muscle. Expression of desmin mutants in mouse muscles induce morphological changes of muscle fibers (irregular shape and size) and the appearance of desmin accumulations around the nuclei (for R406W) or in subsarcolemmal regions of fibers (for E413K). These accumulations seem to occur and disrupt the Z-line, and a strong regeneration was observed in muscle expressing the R406W desmin, which is not the case for E413K. Moreover, both mutants of desmin studied here induce a decrease in muscle force generation capacity. Conclusions In this study we show that AAV-mediated expression of desmin mutants in mouse muscles recapitulate the aggregation features, the decrease in contractile function and the morphological changes observed in patients with myofibrillar myopathy. More importantly, our results suggest that the R406W desmin mutant induces a robust muscle regeneration, which is not the case for the E413K mutant. This difference could help to explain the phenotypic differences observed in patients. Our results highlight the heterogeneous pathogenic mechanisms between different desmin mutants and open the way for new advances in the study of myofibrillar myopathies.
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Affiliation(s)
- Pierre Joanne
- Université Paris Diderot, Sorbonne Paris Cité, CNRS EAC4413, Unit of Functional and Adaptive Biology, Laboratory of Stress and Pathologies of the Cytoskeleton, 75013, Paris, France
| | - Oussama Chourbagi
- Université Paris Diderot, Sorbonne Paris Cité, CNRS EAC4413, Unit of Functional and Adaptive Biology, Laboratory of Stress and Pathologies of the Cytoskeleton, 75013, Paris, France
| | - Christophe Hourdé
- Department of Aging, Stress and Inflammation, Université Pierre et Marie Curie-Paris 6, Sorbonne Universités, 75005, Paris, France
| | - Arnaud Ferry
- Université Pierre et Marie Curie-Paris 6, Sorbonne Universités, UMR S794, INSERM U974, CNRS UMR7215, Institut de Myologie, 75013, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, 75006, Paris, France
| | - Gillian Butler-Browne
- Université Pierre et Marie Curie-Paris 6, Sorbonne Universités, UMR S794, INSERM U974, CNRS UMR7215, Institut de Myologie, 75013, Paris, France
| | - Patrick Vicart
- Université Paris Diderot, Sorbonne Paris Cité, CNRS EAC4413, Unit of Functional and Adaptive Biology, Laboratory of Stress and Pathologies of the Cytoskeleton, 75013, Paris, France
| | - Julie Dumonceaux
- Université Pierre et Marie Curie-Paris 6, Sorbonne Universités, UMR S794, INSERM U974, CNRS UMR7215, Institut de Myologie, 75013, Paris, France
| | - Onnik Agbulut
- Université Paris Diderot, Sorbonne Paris Cité, CNRS EAC4413, Unit of Functional and Adaptive Biology, Laboratory of Stress and Pathologies of the Cytoskeleton, 75013, Paris, France
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Abstract
Lamins are the major components of the nuclear lamina, a filamentous layer found at the interphase between chromatin and the inner nuclear membrane. The lamina supports the nuclear envelope and provides anchorage sites for chromatin. Lamins and their associated proteins are required for most nuclear activities, mitosis, and for linking the nucleoskeleton to the network of cytoskeletal filaments. Mutations in lamins and their associated proteins give rise to a wide range of diseases, collectively called laminopathies. This review focuses on the evolution of the lamin protein family. Evolution from basal metazoans to man will be described on the basis of protein sequence comparisons and analyses of their gene structure. Lamins are the founding members of the family of intermediate filament proteins. How genes encoding cytoplasmic IF proteins could have arisen from the archetypal lamin gene progenitor, can be inferred from a comparison of the respective gene structures. The lamin/IF protein family seems to be restricted to the metazoans. In general, invertebrate genomes harbor only a single lamin gene encoding a B-type lamin. The archetypal lamin gene structure found in basal metazoans is conserved up to the vertebrate lineage. The completely different structure of lamin genes in Caenorhabditis and Drosophila are exceptions rather than the rule within their systematic groups. However, variation in the length of the coiled-coil forming central domain might be more common than previously anticipated. The increase in the number of lamin genes in vertebrates can be explained by two rounds of genome duplication. The origin of lamin A by exon shuffling might explain the processing of prelamin A to the mature non-isoprenylated form of lamin A. By alternative splicing the number of vertebrate lamin proteins has increased even further. Lamin C, an alternative splice form of the LMNA gene, is restricted to mammals. Amphibians and mammals express germline-specific lamins that differ in their protein structure from that of somatic lamins. Evidence is provided that there exist lamin-like proteins outside the metazoan lineage.
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Affiliation(s)
- Annette Peter
- Department for Cell Biology, University of Bremen, Bremen, Germany
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31
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Bruce Fraser R, Parry DA. The role of disulfide bond formation in the structural transition observed in the intermediate filaments of developing hair. J Struct Biol 2012; 180:117-24. [DOI: 10.1016/j.jsb.2012.05.020] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2012] [Revised: 05/27/2012] [Accepted: 05/30/2012] [Indexed: 01/03/2023]
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Characterization of a 65 kDa NIF in the nuclear matrix of the monocot Allium cepa that interacts with nuclear spectrin-like proteins. Cell Biol Int 2012; 36:1097-105. [PMID: 22950797 DOI: 10.1042/cbi20120237] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Plant cells have a well organized nucleus and nuclear matrix, but lack orthologues of the main structural components of the metazoan nuclear matrix. Although data is limited, most plant nuclear structural proteins are coiled-coil proteins, such as the NIFs (nuclear intermediate filaments) in Pisum sativum that cross-react with anti-intermediate filament and anti-lamin antibodies, form filaments 6-12 nm in diameter in vitro, and may play the role of lamins. We have investigated the conservation and features of NIFs in a monocot species, Allium cepa, and compared them with onion lamin-like proteins. Polyclonal antisera against the pea 65 kDa NIF were used in 1D and 2D Western blots, ICM (imunofluorescence confocal microscopy) and IEM (immunoelectron microscopy). Their presence in the nuclear matrix was analysed by differential extraction of nuclei, and their association with structural spectrin-like proteins by co-immunoprecipitation and co-localization in ICM. NIF is a conserved structural component of the nucleus and its matrix in monocots with Mr and pI values similar to those of pea 65 kDa NIF, which localized to the nuclear envelope, perichromatin domains and foci, and to the nuclear matrix, interacting directly with structural nuclear spectrin-like proteins. Its similarities with some of the proteins described as onion lamin-like proteins suggest that they are highly related or perhaps the same proteins.
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Aziz A, Hess JF, Budamagunta MS, Voss JC, Kuzin AP, Huang YJ, Xiao R, Montelione GT, FitzGerald PG, Hunt JF. The structure of vimentin linker 1 and rod 1B domains characterized by site-directed spin-labeling electron paramagnetic resonance (SDSL-EPR) and X-ray crystallography. J Biol Chem 2012; 287:28349-61. [PMID: 22740688 DOI: 10.1074/jbc.m111.334011] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Despite the passage of ∼30 years since the complete primary sequence of the intermediate filament (IF) protein vimentin was reported, the structure remains unknown for both an individual protomer and the assembled filament. In this report, we present data describing the structure of vimentin linker 1 (L1) and rod 1B. Electron paramagnetic resonance spectra collected from samples bearing site-directed spin labels demonstrate that L1 is not a flexible segment between coiled-coils (CCs) but instead forms a rigid, tightly packed structure. An x-ray crystal structure of a construct containing L1 and rod 1B shows that it forms a tetramer comprising two equivalent parallel CC dimers that interact with one another in the form of a symmetrical anti-parallel dimer. Remarkably, the parallel CC dimers are themselves asymmetrical, which enables them to tetramerize rather than undergoing higher order oligomerization. This functionally vital asymmetry in the CC structure, encoded in the primary sequence of rod 1B, provides a striking example of evolutionary exploitation of the structural plasticity of proteins. EPR and crystallographic data consistently suggest that a very short region within L1 represents a minor local distortion in what is likely to be a continuous CC from the end of rod 1A through the entirety of rod 1B. The concordance of this structural model with previously published cross-linking and spectral data supports the conclusion that the crystallographic oligomer represents a native biological structure.
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Affiliation(s)
- Atya Aziz
- Department of Cell Biology and Human Anatomy, University of California, Davis, California 95616, USA
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34
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Stabilization of vimentin coil2 fragment via an engineered disulfide. J Struct Biol 2012; 177:46-53. [DOI: 10.1016/j.jsb.2011.11.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 11/07/2011] [Accepted: 11/09/2011] [Indexed: 11/21/2022]
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35
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Joanne P, Chourbagi O, Agbulut O. [Desmin filaments and their disorganization associated with myofibrillar myopathies]. Biol Aujourdhui 2011; 205:163-77. [PMID: 21982405 DOI: 10.1051/jbio/2011016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Indexed: 11/14/2022]
Abstract
Desmin, the muscle-specific intermediate filament protein, is one of the earliest markers expressed in all muscle tissues during development. It forms a three-dimensional scaffold around the myofibril Z-disc and connects the entire contractile apparatus to the subsarcolemmal cytoskeleton, the nuclei and other cytoplasmic organelles. Desmin is essential for tensile strength and muscle integrity. In humans, disorganization of the desmin network is associated with cardiac and/or skeletal myopathies characterized by accumulation of desmin-containing aggregates in the cells. Currently, 49 mutations have been identified in desmin gene. The majority of these mutations alter desmin filament assembly process through different molecular mechanisms and also its interaction with its protein partners. Here, we will give an overview of desmin network organization as well as the impact of desmin mutations on this process. Furthermore, we will discuss the different molecular mechanisms implicated in perturbation of the desmin filament assembly process.
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Affiliation(s)
- Pierre Joanne
- Université Paris Diderot, Sorbonne Paris Cité, France
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36
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Natsuga K, Nishie W, Smith BJ, Shinkuma S, Smith TA, Parry DAD, Oiso N, Kawada A, Yoneda K, Akiyama M, Shimizu H. Consequences of two different amino-acid substitutions at the same codon in KRT14 indicate definitive roles of structural distortion in epidermolysis bullosa simplex pathogenesis. J Invest Dermatol 2011; 131:1869-76. [PMID: 21593775 DOI: 10.1038/jid.2011.143] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Numerous inherited diseases develop due to missense mutations, leading to an amino-acid substitution. Whether an amino-acid change is pathogenic depends on the level of deleterious effects caused by the amino-acid alteration. We show an example of different structural and phenotypic consequences caused by two individual amino-acid changes at the same position. Epidermolysis bullosa simplex (EBS) is a genodermatosis resulting from KRT5 or KRT14 mutations. Mutation analysis of an EBS family revealed that affected individuals were heterozygous for a, to our knowledge, previously unreported mutation of c.1237G>C (p.Ala413Pro) in KRT14. Interestingly, 2 of 100 unrelated normal controls were heterozygous, and 1 of the 100 was homozygous for a different mutation in this position, c.1237G>A (p.Ala413Thr). In silico modeling of the protein demonstrated deleterious structural effects from proline substitution but not from threonine substitution. In vitro transfection studies revealed a significantly larger number of keratin-clumped cells in HaCaT cells transfected with mutant KRT14 complementary DNA (cDNA) harboring p.Ala413Pro than those transfected with wild-type KRT14 cDNA or mutant KRT14 cDNA harboring p.Ala413Thr. These results show that changes in two distinct amino acids at a locus are destined to elicit different phenotypes due to the degree of structural distortion resulting from the amino-acid alterations.
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Affiliation(s)
- Ken Natsuga
- Department of Dermatology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
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37
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Kapinos LE, Burkhard P, Herrmann H, Aebi U, Strelkov SV. Simultaneous Formation of Right- and Left-handed Anti-parallel Coiled-coil Interfaces by a Coil2 Fragment of Human Lamin A. J Mol Biol 2011; 408:135-46. [DOI: 10.1016/j.jmb.2011.02.037] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Revised: 02/15/2011] [Accepted: 02/16/2011] [Indexed: 10/18/2022]
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38
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Cabeen MT, Herrmann H, Jacobs-Wagner C. The domain organization of the bacterial intermediate filament-like protein crescentin is important for assembly and function. Cytoskeleton (Hoboken) 2011; 68:205-19. [PMID: 21360832 PMCID: PMC3087291 DOI: 10.1002/cm.20505] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 02/01/2011] [Accepted: 02/02/2011] [Indexed: 01/08/2023]
Abstract
Crescentin is a bacterial filament-forming protein that exhibits domain organization features found in metazoan intermediate filament (IF) proteins. Structure-function studies of eukaryotic IFs have been hindered by a lack of simple genetic systems and easily quantifiable phenotypes. Here we exploit the characteristic localization of the crescentin structure along the inner curvature of Caulobacter crescentus cells and the loss of cell curvature associated with impaired crescentin function to analyze the importance of the domain organization of crescentin. By combining biochemistry and ultrastructural analysis in vitro with cellular localization and functional studies, we show that crescentin requires its distinctive domain organization, and furthermore that different structural elements have distinct structural and functional contributions. The head domain can be functionally subdivided into two subdomains; the first (amino-terminal) is required for function but not assembly, while the second is necessary for structure assembly. The rod domain is similarly required for structure assembly, and the linker L1 appears important to prevent runaway assembly into nonfunctional aggregates. The data also suggest that the stutter and the tail domain have critical functional roles in stabilizing crescentin structures against disassembly by monovalent cations in the cytoplasm. This study suggests that the IF-like behavior of crescentin is a consequence of its domain organization, implying that the IF protein layout is an adaptable cytoskeletal motif, much like the actin and tubulin folds, that is broadly exploited for various functions throughout life from bacteria to humans.
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Affiliation(s)
- Matthew T Cabeen
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut, USA
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39
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The role of the ubiquitin proteasome pathway in keratin intermediate filament protein degradation. Ann Am Thorac Soc 2010; 7:71-6. [PMID: 20160151 DOI: 10.1513/pats.200908-089js] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Lung injury, whether caused by hypoxic or mechanical stresses, elicits a variety of responses at the cellular level. Alveolar epithelial cells respond and adapt to such injurious stimuli by reorganizing the cellular cytoskeleton, mainly accomplished through modification of the intermediate filament (IF) network. The structural and mechanical integrity in epithelial cells is maintained through this adaptive reorganization response. Keratin, the predominant IF expressed in epithelial cells, displays highly dynamic properties in response to injury, sometimes in the form of degradation of the keratin IF network. Post-translational modification, such as phosphorylation, targets keratin proteins for degradation in these circumstances. As with other structural and regulatory proteins, turnover of keratin is regulated by the ubiquitin (Ub)-proteasome pathway. The degradation process begins with activation of Ub by the Ub-activating enzyme (E1), followed by the exchange of Ub to the Ub-conjugating enzyme (E2). E2 shuttles the Ub molecule to the substrate-specific Ub ligase (E3), which then delivers the Ub to the substrate protein, thereby targeting it for degradation. In some cases of injury and IF-related disease, aggresomes form in epithelial cells. The mechanisms that regulate aggresome formation are currently unknown, although proteasome overload may play a role. Therefore, a more complete understanding of keratin degradation--causes, mechanisms, and consequences--will allow for a greater understanding of epithelial cell biology and lung pathology alike.
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40
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Lin YC, Broedersz CP, Rowat AC, Wedig T, Herrmann H, Mackintosh FC, Weitz DA. Divalent cations crosslink vimentin intermediate filament tail domains to regulate network mechanics. J Mol Biol 2010; 399:637-44. [PMID: 20447406 DOI: 10.1016/j.jmb.2010.04.054] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Revised: 04/24/2010] [Accepted: 04/27/2010] [Indexed: 01/30/2023]
Abstract
Intermediate filament networks in the cytoplasm and nucleus are critical for the mechanical integrity of metazoan cells. However, the mechanism of crosslinking in these networks and the origins of their mechanical properties are not understood. Here, we study the elastic behavior of in vitro networks of the intermediate filament protein vimentin. Rheological experiments reveal that vimentin networks stiffen with increasing concentrations of Ca(2+) and Mg(2+), showing that divalent cations act as crosslinkers. We quantitatively describe the elastic response of vimentin networks over five decades of applied stress using a theory that treats the divalent cations as crosslinkers: at low stress, the behavior is entropic in origin, and increasing stress pulls out thermal fluctuations from single filaments, giving rise to a nonlinear response; at high stress, enthalpic stretching of individual filaments significantly modifies the nonlinearity. We investigate the elastic properties of networks formed by a series of protein variants with stepwise tail truncations and find that the last 11 amino acids of the C-terminal tail domain mediate crosslinking by divalent ions. We determined the single-filament persistence length, l(P) approximately 0.5 mum, and Young's modulus, Y approximately 9 MPa; both are consistent with literature values. Our results provide insight into a crosslinking mechanism for vimentin networks and suggest that divalent ions may help regulate the cytoskeletal structure and mechanical properties of cells.
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Affiliation(s)
- Yi-Chia Lin
- Department of Physics, Harvard University, Pierce 231, 29 Oxford Street, Cambridge, MA 02138, USA
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41
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Bragulla HH, Homberger DG. Structure and functions of keratin proteins in simple, stratified, keratinized and cornified epithelia. J Anat 2010; 214:516-59. [PMID: 19422428 DOI: 10.1111/j.1469-7580.2009.01066.x] [Citation(s) in RCA: 397] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Historically, the term 'keratin' stood for all of the proteins extracted from skin modifications, such as horns, claws and hooves. Subsequently, it was realized that this keratin is actually a mixture of keratins, keratin filament-associated proteins and other proteins, such as enzymes. Keratins were then defined as certain filament-forming proteins with specific physicochemical properties and extracted from the cornified layer of the epidermis, whereas those filament-forming proteins that were extracted from the living layers of the epidermis were grouped as 'prekeratins' or 'cytokeratins'. Currently, the term 'keratin' covers all intermediate filament-forming proteins with specific physicochemical properties and produced in any vertebrate epithelia. Similarly, the nomenclature of epithelia as cornified, keratinized or non-keratinized is based historically on the notion that only the epidermis of skin modifications such as horns, claws and hooves is cornified, that the non-modified epidermis is a keratinized stratified epithelium, and that all other stratified and non-stratified epithelia are non-keratinized epithelia. At this point in time, the concepts of keratins and of keratinized or cornified epithelia need clarification and revision concerning the structure and function of keratin and keratin filaments in various epithelia of different species, as well as of keratin genes and their modifications, in view of recent research, such as the sequencing of keratin proteins and their genes, cell culture, transfection of epithelial cells, immunohistochemistry and immunoblotting. Recently, new functions of keratins and keratin filaments in cell signaling and intracellular vesicle transport have been discovered. It is currently understood that all stratified epithelia are keratinized and that some of these keratinized stratified epithelia cornify by forming a Stratum corneum. The processes of keratinization and cornification in skin modifications are different especially with respect to the keratins that are produced. Future research in keratins will provide a better understanding of the processes of keratinization and cornification of stratified epithelia, including those of skin modifications, of the adaptability of epithelia in general, of skin diseases, and of the changes in structure and function of epithelia in the course of evolution. This review focuses on keratins and keratin filaments in mammalian tissue but keratins in the tissues of some other vertebrates are also considered.
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Affiliation(s)
- Hermann H Bragulla
- Department of Comparative Biomedical Sciences, Louisiana State University, Baton Rouge, 70803, USA.
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Divergent Molecular Effects of Desmin Mutations on Protein Assembly in Myofibrillar Myopathy. J Neuropathol Exp Neurol 2010; 69:415-24. [DOI: 10.1097/nen.0b013e3181d71305] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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43
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Kapinos LE, Schumacher J, Mücke N, Machaidze G, Burkhard P, Aebi U, Strelkov SV, Herrmann H. Characterization of the head-to-tail overlap complexes formed by human lamin A, B1 and B2 "half-minilamin" dimers. J Mol Biol 2010; 396:719-31. [PMID: 20004208 DOI: 10.1016/j.jmb.2009.12.001] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2009] [Revised: 11/30/2009] [Accepted: 12/01/2009] [Indexed: 11/17/2022]
Abstract
Half-minilamins, representing amino- and carboxy-terminal fragments of human lamins A, B1 and B2 with a truncated central rod domain, were investigated for their ability to form distinct head-to-tail-type dimer complexes. This mode of interaction represents an essential step in the longitudinal assembly reaction exhibited by full-length lamin dimers. As determined by analytical ultracentrifugation, the amino-terminal fragments were soluble under low ionic strength conditions sedimenting with distinct profiles and s-values (1.6-1.8 S) indicating the formation of coiled-coil dimers. The smaller carboxy-terminal fragments were, except for lamin B2, largely insoluble under these conditions. However, after equimolar amounts of homotypic amino- and carboxy-terminal lamin fragments had been mixed in 4 M urea, upon subsequent renaturation the carboxy-terminal fragments were completely rescued from precipitation and distinct soluble complexes with higher s-values (2.3-2.7 S) were obtained. From this behavior, we conclude that the amino- and carboxy-terminal coiled-coil dimers interact to form distinct oligomers (i.e. tetramers). Furthermore, a corresponding interaction occurred also between heterotypic pairs of A- and B-type lamin fragments. Hence, A-type lamin dimers may interact with B-type lamin dimers head-to-tail to yield linear polymers. These findings indicate that a lamin dimer principally has the freedom for a "combinatorial" head-to-tail association with all types of lamins, a property that might be of significant importance for the assembly of the nuclear lamina. Furthermore, we suggest that the head-to-tail interaction of the rod end domains represents a principal step in the assembly of cytoplasmic intermediate filament proteins too.
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Affiliation(s)
- Larisa E Kapinos
- M.E. Müller Institute for Structural Biology, Biozentrum, University of Basel, CH-4056 Basel, Switzerland
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44
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Wilson NJ, Messenger AG, Leachman SA, O'Toole EA, Lane EB, Irwin McLean W, Smith FJ. Keratin K6c Mutations Cause Focal Palmoplantar Keratoderma. J Invest Dermatol 2010; 130:425-9. [DOI: 10.1038/jid.2009.215] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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45
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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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46
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Goldfarb LG, Dalakas MC. Tragedy in a heartbeat: malfunctioning desmin causes skeletal and cardiac muscle disease. J Clin Invest 2009; 119:1806-13. [PMID: 19587455 PMCID: PMC2701871 DOI: 10.1172/jci38027] [Citation(s) in RCA: 160] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Muscle fiber deterioration resulting in progressive skeletal muscle weakness, heart failure, and respiratory distress occurs in more than 20 inherited myopathies. As discussed in this Review, one of the newly identified myopathies is desminopathy, a disease caused by dysfunctional mutations in desmin, a type III intermediate filament protein, or alphaB-crystallin, a chaperone for desmin. The range of clinical manifestations in patients with desminopathy is wide and may overlap with those observed in individuals with other myopathies. Awareness of this disease needs to be heightened, diagnostic criteria reliably outlined, and molecular testing readily available; this would ensure prevention of sudden death from cardiac arrhythmias and other complications.
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Affiliation(s)
- Lev G. Goldfarb
- National Institute of Neurological Disorders and Stroke, NIH, Bethesda, Maryland, USA.
Imperial College London, Hammersmith Hospital Campus, London, United Kingdom
| | - Marinos C. Dalakas
- National Institute of Neurological Disorders and Stroke, NIH, Bethesda, Maryland, USA.
Imperial College London, Hammersmith Hospital Campus, London, United Kingdom
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47
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Herrmann H, Strelkov SV, Burkhard P, Aebi U. Intermediate filaments: primary determinants of cell architecture and plasticity. J Clin Invest 2009; 119:1772-83. [PMID: 19587452 DOI: 10.1172/jci38214] [Citation(s) in RCA: 220] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Intermediate filaments (IFs) are major constituents of the cytoskeleton and nuclear boundary in animal cells. They are of prime importance for the functional organization of structural elements. Depending on the cell type, morphologically similar but biochemically distinct proteins form highly viscoelastic filament networks with multiple nanomechanical functions. Besides their primary role in cell plasticity and their established function as cellular stress absorbers, recently discovered gene defects have elucidated that structural alterations of IFs can affect their involvement both in signaling and in controlling gene regulatory networks. Here, we highlight the basic structural and functional properties of IFs and derive a concept of how mutations may affect cellular architecture and thereby tissue construction and physiology.
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Affiliation(s)
- Harald Herrmann
- Group Functional Architecture of the Cell, German Cancer Research Center, Heidelberg, Germany.
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48
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Minin AA, Moldaver MV. Intermediate vimentin filaments and their role in intracellular organelle distribution. BIOCHEMISTRY (MOSCOW) 2009; 73:1453-66. [PMID: 19216711 DOI: 10.1134/s0006297908130063] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Intermediate filaments (IF) represent one of three main cytoskeletal structures in most animal cells. The human IF protein family includes about 70 members divided into five main groups. The characteristic feature of IF is that in various cells and tissues they are formed by proteins of different groups. Structures of all IF proteins follow a unique scheme: a central alpha-helical part is flanked at the N and C ends by positively charged polypeptide chains devoid of a clear secondary structure. The central part is highly conserved for all proteins in all animals, whereas the N and C termini strongly differ both in size and amino acid composition. This review covers the broad spectrum of recent investigations of IF structure and diverse functions. Special attention is paid to the regulatory mechanisms of IF functions, mainly to phosphorylation by different protein kinases whose role is well studied. The review gives examples of hereditary diseases associated with mutations of some IF proteins, which point to an important physiological role of these cytoskeletal structures.
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Affiliation(s)
- A A Minin
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia.
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Meier M, Padilla GP, Herrmann H, Wedig T, Hergt M, Patel TR, Stetefeld J, Aebi U, Burkhard P. Vimentin coil 1A-A molecular switch involved in the initiation of filament elongation. J Mol Biol 2009; 390:245-61. [PMID: 19422834 DOI: 10.1016/j.jmb.2009.04.067] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Revised: 04/27/2009] [Accepted: 04/29/2009] [Indexed: 12/25/2022]
Abstract
Interestingly, our previously published structure of the coil 1A fragment of the human intermediate filament protein vimentin turned out to be a monomeric alpha-helical coil instead of the expected dimeric coiled coil. However, the 39-amino-acid-long helix had an intrinsic curvature compatible with a coiled coil. We have now designed four mutants of vimentin coil 1A, modifying key a and d positions in the heptad repeat pattern, with the aim of investigating the molecular criteria that are needed to stabilize a dimeric coiled-coil structure. We have analysed the biophysical properties of the mutants by circular dichroism spectroscopy, analytical ultracentrifugation and X-ray crystallography. All four mutants exhibited an increased stability over the wild type as indicated by a rise in the melting temperature (T(m)). At a concentration of 0.1 mg/ml, the T(m) of the peptide with the single point mutation Y117L increased dramatically by 46 degrees C compared with the wild-type peptide. In general, the introduction of a single stabilizing point mutation at an a or a d position did induce the formation of a stable dimer as demonstrated by sedimentation equilibrium experiments. The dimeric oligomerisation state of the Y117L peptide was furthermore confirmed by X-ray crystallography, which yielded a structure with a genuine coiled-coil geometry. Most notably, when this mutation was introduced into full-length vimentin, filament assembly was completely arrested at the unit-length filament (ULF) level, both in vitro and in cDNA-transfected cultured cells. Therefore, the low propensity of the wild-type coil 1A to form a stable two-stranded coiled coil is most likely a prerequisite for the end-to-end annealing of ULFs into filaments. Accordingly, the coil 1A domains might "switch" from a dimeric alpha-helical coiled coil into a more open structure, thus mediating, within the ULFs, the conformational rearrangements of the tetrameric subunits that are needed for the intermediate filament elongation reaction.
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Affiliation(s)
- Markus Meier
- Department of Chemistry, University of Manitoba, Winnipeg, Canada.
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50
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Engel A. Chapter 9 Scanning Transmission Electron Microscopy. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/s1076-5670(09)59009-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
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