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Dean WF, Albert RM, Nawara TJ, Ubil M, Beggs RR, Mattheyses AL. Dsg2 ectodomain organization increases throughout desmosome assembly. Cell Adh Migr 2024; 18:1-13. [PMID: 38566311 PMCID: PMC10993919 DOI: 10.1080/19336918.2024.2333366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 03/18/2024] [Indexed: 04/04/2024] Open
Abstract
Desmosomes are intercellular junctions that regulate mechanical integrity in epithelia and cardiac muscle. Dynamic desmosome remodeling is essential for wound healing and development, yet the mechanisms governing junction assembly remain elusive. While we and others have shown that cadherin ectodomains are highly organized, how this ordered architecture emerges during assembly is unknown. Using fluorescence polarization microscopy, we show that desmoglein 2 (Dsg2) ectodomain order gradually increases during 8 h of assembly, coinciding with increasing adhesive strength. In a scratch wound assay, we observed a similar increase in order in desmosomes assembling at the leading edge of migratory cells. Together, our findings indicate that cadherin organization is a hallmark of desmosome maturity and may play a role in conferring adhesive strength.
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Affiliation(s)
- William F. Dean
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Rose M. Albert
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Tomasz J. Nawara
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Melanie Ubil
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Reena R. Beggs
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Alexa L. Mattheyses
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
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2
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Göz M, Pohl G, Steinecker SM, Walhorn V, Milting H, Anselmetti D. Arrhythmogenic cardiomyopathy-related cadherin variants affect desmosomal binding kinetics. J Mol Cell Cardiol 2024; 195:36-44. [PMID: 39079569 DOI: 10.1016/j.yjmcc.2024.07.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 07/09/2024] [Accepted: 07/25/2024] [Indexed: 08/05/2024]
Abstract
Cadherins are calcium dependent adhesion proteins that establish and maintain the intercellular mechanical contact by bridging the gap between adjacent cells. Desmoglein-2 (Dsg2) and desmocollin-2 (Dsc2) are tissue specific cadherin isoforms of the cell-cell contact in cardiac desmosomes. Mutations in the DSG2-gene and in the DSC2-gene are related to arrhythmogenic right ventricular cardiomyopathy (ARVC) a rare but severe heart muscle disease. Here, several possible homophilic and heterophilic binding interactions of wild-type Dsg2, wild-type Dsc2, as well as one Dsg2- and two Dsc2-variants, each associated with ARVC, are investigated. Using single molecule force spectroscopy (SMFS) with atomic force microscopy (AFM) and applying Jarzynski's equality the kinetics and thermodynamics of Dsg2/Dsc2 interaction can be determined. The free energy landscape of Dsg2/Dsc2 dimerization exposes a high activation energy barrier, which is in line with the proposed strand-swapping binding motif. Although the binding motif is not affected by any of the mutations, the binding kinetics of the interactions differ significantly from the wild-type. While wild-type cadherins exhibit an average complex lifetime of approx. 0.3 s interactions involving a variant consistently show - lifetimes that are substantially larger. The lifetimes of the wild-type interactions give rise to the picture of a dynamic adhesion interface consisting of continuously dissociating and (re)associating molecular bonds, while the delayed binding kinetics of interactions involving an ARVC-associated variant might be part of the pathogenesis. Our data provide a comprehensive and consistent thermodynamic and kinetic description of cardiac cadherin binding, allowing detailed insight into the molecular mechanisms of cell adhesion.
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Affiliation(s)
- Manuel Göz
- Department of Physics, Experimental Biophysics and Applied Nanoscience, Bielefeld University, Universitätsstraße 25, Bielefeld, Germany
| | - Greta Pohl
- Erich & Hanna Klessmann Institute for Cardiovascular Research and Development, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Georgstraße 11, Bad Oeynhausen, Germany
| | - Sylvia M Steinecker
- Department of Physics, Experimental Biophysics and Applied Nanoscience, Bielefeld University, Universitätsstraße 25, Bielefeld, Germany
| | - Volker Walhorn
- Department of Physics, Experimental Biophysics and Applied Nanoscience, Bielefeld University, Universitätsstraße 25, Bielefeld, Germany.
| | - Hendrik Milting
- Erich & Hanna Klessmann Institute for Cardiovascular Research and Development, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Georgstraße 11, Bad Oeynhausen, Germany
| | - Dario Anselmetti
- Department of Physics, Experimental Biophysics and Applied Nanoscience, Bielefeld University, Universitätsstraße 25, Bielefeld, Germany
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3
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Bharathan NK, Mattheyses AL, Kowalczyk AP. The desmosome comes into focus. J Cell Biol 2024; 223:e202404120. [PMID: 39120608 PMCID: PMC11317759 DOI: 10.1083/jcb.202404120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 07/26/2024] [Accepted: 07/29/2024] [Indexed: 08/10/2024] Open
Abstract
The desmosome is a cell-cell adhesive junction that provides integrity and mechanical resistance to tissues through its attachment to the intermediate filament cytoskeleton. Defects in desmosomes cause diseases impacting the heart, epidermis, and other epithelia. In this review, we provide a historical perspective on the discovery of the desmosome and how the evolution of cellular imaging technologies revealed insights into desmosome structure and function. We also discuss recent findings using contemporary imaging approaches that have informed the molecular order, three-dimensional architecture, and associations of desmosomes with organelles such as the endoplasmic reticulum. Finally, we provide an updated model of desmosome molecular organization and speculate upon novel functions of this cell junction as a signaling center for sensing mechanical and other forms of cell stress.
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Affiliation(s)
- Navaneetha Krishnan Bharathan
- Departments of Dermatology and Cellular and Molecular Physiology, Pennsylvania State University, College of Medicine, Hershey, PA, USA
| | - Alexa L Mattheyses
- Department of Cell, Developmental, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Andrew P Kowalczyk
- Departments of Dermatology and Cellular and Molecular Physiology, Pennsylvania State University, College of Medicine, Hershey, PA, USA
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4
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Harmon RM, Ayers JL, McCarthy EF, Kowalczyk AP, Green KJ, Simpson CL. Pumping the Breaks on Acantholytic Skin Disorders: Targeting Calcium Pumps, Desmosomes, and Downstream Signaling in Darier, Hailey-Hailey, and Grover Disease. J Invest Dermatol 2024:S0022-202X(24)01925-0. [PMID: 39207315 DOI: 10.1016/j.jid.2024.06.1289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2024] [Revised: 06/11/2024] [Accepted: 06/14/2024] [Indexed: 09/04/2024]
Abstract
Acantholytic skin disorders, by definition, compromise intercellular adhesion between epidermal keratinocytes. The root cause of blistering in these diseases traces back to direct disruption of adhesive cell-cell junctions, exemplified by autoantibody-mediated attack on desmosomes in pemphigus. However, genetic acantholytic disorders originate from more indirect mechanisms. Darier disease and Hailey-Hailey disease arise from mutations in the endoplasmic reticulum calcium pump, SERCA2, and the Golgi calcium/manganese pump, SPCA1, respectively. Though the disease-causing mutations have been known for nearly 25 years, the mechanistic linkage between dysregulation of intracellular ion stores and weakening of cell-cell junctions at the plasma membrane remains puzzling. The molecular underpinnings of a related idiopathic disorder, Grover disease, are even less understood. Due to an incomplete understanding of acantholytic pathology at the molecular level, these disorders lack proven, targeted treatment options, leaving patients with the significant physical and psychological burdens of chronic skin blistering, infections, and pain. This article aims to review what is known at the molecular, cellular, and clinical levels regarding these under-studied disorders and to highlight knowledge gaps and promising ongoing research. Armed with this knowledge, our goal is to aid investigators in defining essential questions about disease pathogenesis and to accelerate progress toward novel therapeutic strategies.
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Affiliation(s)
- Robert M Harmon
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA; Department of Dermatology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.
| | - Jessica L Ayers
- Molecular Medicine and Mechanisms of Disease PhD Program, Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, USA; Department of Dermatology, University of Washington, Seattle, Washington, USA; Institute for Stem Cell & Regenerative Medicine, University of Washington, Seattle, Washington, USA
| | - Erin F McCarthy
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA; Department of Dermatology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Andrew P Kowalczyk
- Department of Dermatology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA; Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
| | - Kathleen J Green
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA; Department of Dermatology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Cory L Simpson
- Department of Dermatology, University of Washington, Seattle, Washington, USA; Institute for Stem Cell & Regenerative Medicine, University of Washington, Seattle, Washington, USA.
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5
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Dean WF, Nawara TJ, Albert RM, Mattheyses AL. OOPS: Object-Oriented Polarization Software for analysis of fluorescence polarization microscopy images. PLoS Comput Biol 2024; 20:e1011723. [PMID: 39133751 PMCID: PMC11341096 DOI: 10.1371/journal.pcbi.1011723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 08/22/2024] [Accepted: 08/02/2024] [Indexed: 08/24/2024] Open
Abstract
Most essential cellular functions are performed by proteins assembled into larger complexes. Fluorescence Polarization Microscopy (FPM) is a powerful technique that goes beyond traditional imaging methods by allowing researchers to measure not only the localization of proteins within cells, but also their orientation or alignment within complexes or cellular structures. FPM can be easily integrated into standard widefield microscopes with the addition of a polarization modulator. However, the extensive image processing and analysis required to interpret the data have limited its widespread adoption. To overcome these challenges and enhance accessibility, we introduce OOPS (Object-Oriented Polarization Software), a MATLAB package for object-based analysis of FPM data. By combining flexible image segmentation and novel object-based analyses with a high-throughput FPM processing pipeline, OOPS empowers researchers to simultaneously study molecular order and orientation in individual biological structures; conduct population assessments based on morphological features, intensity statistics, and FPM measurements; and create publication-quality visualizations, all within a user-friendly graphical interface. Here, we demonstrate the power and versatility of our approach by applying OOPS to punctate and filamentous structures.
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Affiliation(s)
- William F. Dean
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Tomasz J. Nawara
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Rose M. Albert
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Alexa L. Mattheyses
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
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6
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Zhang B, Wu Y, Yang X, Xiang Y, Yang B. Molecular insight into arrhythmogenic cardiomyopathy caused by DSG2 mutations. Biomed Pharmacother 2023; 167:115448. [PMID: 37696084 DOI: 10.1016/j.biopha.2023.115448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 09/01/2023] [Accepted: 09/04/2023] [Indexed: 09/13/2023] Open
Abstract
Mutant desmoglein 2 (DSG2) is the second most common pathogenic gene in arrhythmogenic cardiomyopathy (ACM), accounting for approximately 10% of ACM cases. In addition to common clinical and pathological features, ACM caused by mutant DSG2 has specific characteristics, manifesting as left ventricle involvement and a high risk of heart failure. Pathological studies have shown extensive cardiomyocyte necrosis, infiltration of immune cells, and fibrofatty replacement in both ventricles, as well as abnormal desmosome structures in the hearts of humans and mice with mutant DSG2-related ACM. Although desmosome dysfunction is a common pathway in the pathogenesis of mutant DSG2-related ACM, the mechanisms underlying this dysfunction vary among mutations. Desmosome dysfunction induces cardiomyocyte injury, plakoglobin dislocation, and gap junction dysfunction, all of which contribute to the initiation and progression of ACM. Additionally, dysregulated inflammation, overactivation of transforming growth factor-beta-1 signaling and endoplasmic reticulum stress, and cardiac metabolic dysfunction contribute to the pathogenesis of ACM caused by mutant DSG2. These features demonstrate that patients with mutant DSG2-related ACM should be managed individually and precisely based on the genotype and phenotype. Further studies are needed to investigate the underlying mechanisms and to identify novel therapies to reverse or attenuate the progression of ACM caused by mutant DSG2.
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Affiliation(s)
- Baowei Zhang
- Department of Cardiology, Shanghai East Hospital, Tongji University School of Medicine, 150 Jimo Road, Pudong, Shanghai 200120, PR China
| | - Yizhang Wu
- Department of Cardiology, Shanghai East Hospital, Tongji University School of Medicine, 150 Jimo Road, Pudong, Shanghai 200120, PR China
| | - Xingbo Yang
- Shanghai East Hospital, School of Life Sciences and Technology, Tongji University, 150 Jimo Road, Pudong, Shanghai 200120, PR China
| | - Yaozu Xiang
- Shanghai East Hospital, School of Life Sciences and Technology, Tongji University, 150 Jimo Road, Pudong, Shanghai 200120, PR China.
| | - Bing Yang
- Department of Cardiology, Shanghai East Hospital, Tongji University School of Medicine, 150 Jimo Road, Pudong, Shanghai 200120, PR China.
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7
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Nielsen MS, van Opbergen CJM, van Veen TAB, Delmar M. The intercalated disc: a unique organelle for electromechanical synchrony in cardiomyocytes. Physiol Rev 2023; 103:2271-2319. [PMID: 36731030 PMCID: PMC10191137 DOI: 10.1152/physrev.00021.2022] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 01/24/2023] [Accepted: 01/30/2023] [Indexed: 02/04/2023] Open
Abstract
The intercalated disc (ID) is a highly specialized structure that connects cardiomyocytes via mechanical and electrical junctions. Although described in some detail by light microscopy in the 19th century, it was in 1966 that electron microscopy images showed that the ID represented apposing cell borders and provided detailed insight into the complex ID nanostructure. Since then, much has been learned about the ID and its molecular composition, and it has become evident that a large number of proteins, not all of them involved in direct cell-to-cell coupling via mechanical or gap junctions, reside at the ID. Furthermore, an increasing number of functional interactions between ID components are emerging, leading to the concept that the ID is not the sum of isolated molecular silos but an interacting molecular complex, an "organelle" where components work in concert to bring about electrical and mechanical synchrony. The aim of the present review is to give a short historical account of the ID's discovery and an updated overview of its composition and organization, followed by a discussion of the physiological implications of the ID architecture and the local intermolecular interactions. The latter will focus on both the importance of normal conduction of cardiac action potentials as well as the impact on the pathophysiology of arrhythmias.
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Affiliation(s)
- Morten S Nielsen
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Chantal J M van Opbergen
- The Leon Charney Division of Cardiology, New York University Grossmann School of Medicine, New York, New York, United States
| | - Toon A B van Veen
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Mario Delmar
- The Leon Charney Division of Cardiology, New York University Grossmann School of Medicine, New York, New York, United States
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8
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Reactivation of PPAR α alleviates myocardial lipid accumulation and cardiac dysfunction by improving fatty acid β-oxidation in Dsg2-deficient arrhythmogenic cardiomyopathy. Acta Pharm Sin B 2023; 13:192-203. [PMID: 36815030 PMCID: PMC9939300 DOI: 10.1016/j.apsb.2022.05.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 03/27/2022] [Accepted: 04/02/2022] [Indexed: 02/07/2023] Open
Abstract
Arrhythmogenic cardiomyopathy (ACM), a fatal heart disease characterized by fibroadipocytic replacement of cardiac myocytes, accounts for 20% of sudden cardiac death and lacks effective treatment. It is often caused by mutations in desmosome proteins, with Desmoglein-2 (DSG2) mutations as a common etiology. However, the mechanism underlying the accumulation of fibrofatty in ACM remains unknown, which impedes the development of curative treatment. Here we investigated the fat accumulation and the underlying mechanism in a mouse model of ACM induced by cardiac-specific knockout of Dsg2 (CS-Dsg2 -/-). Heart failure and cardiac lipid accumulation were observed in CS-Dsg2 -/- mice. We demonstrated that these phenotypes were caused by decline of fatty acid (FA) β-oxidation resulted from impaired mammalian target of rapamycin (mTOR) signaling. Rapamycin worsened while overexpression of mTOR and 4EBP1 rescued the FA β-oxidation pathway in CS-Dsg2 -/- mice. Reactivation of PPARα by fenofibrate or AAV9-Pparα significantly alleviated the lipid accumulation and restored cardiac function. Our results suggest that impaired mTOR-4EBP1-PPARα-dependent FA β-oxidation contributes to myocardial lipid accumulation in ACM and PPARα may be a potential target for curative treatment of ACM.
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9
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Hoffmann PC, Kreysing JP, Khusainov I, Tuijtel MW, Welsch S, Beck M. Structures of the eukaryotic ribosome and its translational states in situ. Nat Commun 2022; 13:7435. [PMID: 36460643 PMCID: PMC9718845 DOI: 10.1038/s41467-022-34997-w] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 11/15/2022] [Indexed: 12/03/2022] Open
Abstract
Ribosomes translate genetic information into primary structure. During translation, various cofactors transiently bind to the ribosome that undergoes prominent conformational and structural changes. Different translational states of ribosomes have been well characterized in vitro. However, to which extent the known translational states are representative of the native situation inside cells has thus far only been addressed in prokaryotes. Here, we apply cryo-electron tomography to cryo-FIB milled Dictyostelium discoideum cells combined with subtomogram averaging and classification. We obtain an in situ structure that is locally resolved up to 3 Angstrom, the distribution of eukaryotic ribosome translational states, and unique arrangement of rRNA expansion segments. Our work demonstrates the use of in situ structural biology techniques for identifying distinct ribosome states within the cellular environment.
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Affiliation(s)
- Patrick C Hoffmann
- Department of Molecular Sociology, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438, Frankfurt am Main, Germany
| | - Jan Philipp Kreysing
- Department of Molecular Sociology, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438, Frankfurt am Main, Germany
- Department of Molecular Sociology, IMPRS on Cellular Biophysics, Max-von-Laue-Straße 3, 60438, Frankfurt am Main, Germany
| | - Iskander Khusainov
- Department of Molecular Sociology, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438, Frankfurt am Main, Germany
| | - Maarten W Tuijtel
- Department of Molecular Sociology, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438, Frankfurt am Main, Germany
| | - Sonja Welsch
- Central Electron Microscopy Facility, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438, Frankfurt am Main, Germany
| | - Martin Beck
- Department of Molecular Sociology, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438, Frankfurt am Main, Germany.
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10
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Dean WF, Mattheyses AL. Defining domain-specific orientational order in the desmosomal cadherins. Biophys J 2022; 121:4325-4341. [PMID: 36225113 PMCID: PMC9703042 DOI: 10.1016/j.bpj.2022.10.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 09/12/2022] [Accepted: 10/06/2022] [Indexed: 01/25/2023] Open
Abstract
Desmosomes are large, macromolecular protein assemblies that mechanically couple the intermediate filament cytoskeleton to sites of cadherin-mediated cell adhesion, thereby providing structural integrity to tissues that routinely experience large forces. Proper desmosomal adhesion is necessary for the normal development and maintenance of vertebrate tissues, such as epithelia and cardiac muscle, while dysfunction can lead to severe disease of the heart and skin. Therefore, it is important to understand the relationship between desmosomal adhesion and the architecture of the molecules that form the adhesive interface, the desmosomal cadherins (DCs). However, desmosomes are embedded in two plasma membranes and are linked to the cytoskeletal networks of two cells, imposing extreme difficulty on traditional structural studies of DC architecture, which have yielded conflicting results. Consequently, the relationship between DC architecture and adhesive function remains unclear. To overcome these challenges, we utilized excitation-resolved fluorescence polarization microscopy to quantify the orientational order of the extracellular and intracellular domains of three DC isoforms: desmoglein 2, desmocollin 2, and desmoglein 3. We found that DC ectodomains were significantly more ordered than their cytoplasmic counterparts, indicating a drastic difference in DC architecture between opposing sides of the plasma membrane. This difference was conserved among all DCs tested, suggesting that it may be an important feature of desmosomal architecture. Moreover, our findings suggest that the organization of DC ectodomains is predominantly the result of extracellular adhesive interactions. We employed azimuthal orientation mapping to show that DC ectodomains are arranged with rotational symmetry about the membrane normal. Finally, we performed a series of mathematical simulations to test the feasibility of a recently proposed antiparallel arrangement of DC ectodomains, finding that it is supported by our experimental data. Importantly, the strategies employed here have the potential to elucidate molecular mechanisms for diseases that result from defective desmosome architecture.
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Affiliation(s)
- William F Dean
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Alexa L Mattheyses
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama.
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11
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Long DM, Singh MK, Small KA, Watt J. Cryo-FIB for TEM investigation of soft matter and beam sensitive energy materials. NANOTECHNOLOGY 2022; 33:503001. [PMID: 36121746 DOI: 10.1088/1361-6528/ac92eb] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 09/18/2022] [Indexed: 06/15/2023]
Abstract
Primarily driven by structural biology, the rapid advances in cryogenic electron microscopy techniques are now being adopted and applied by materials scientists. Samples that inherently have electron transparency can be rapidly frozen (vitrified) in amorphous ice and imaged directly on a cryogenic transmission electron microscopy (cryo-TEM), however this is not the case for many important materials systems, which can consist of layered structures, embedded architectures, or be contained within a device. Cryogenic focused ion beam (cryo-FIB) lift-out procedures have recently been developed to extract intact regions and interfaces of interest, that can then be thinned to electron transparency and transferred to the cryo-TEM for characterization. Several detailed studies have been reported demonstrating the cryo-FIB lift-out procedure, however due to its relative infancy in materials science improvements are still required to ensure the technique becomes more accessible and routinely successful. Here, we review recent results on the preparation of cryo-TEM lamellae using cryo-FIB and show that the technique is broadly applicable to a range of soft matter and beam sensitive energy materials. We then present a tutorial that can guide the materials scientist through the cryo-FIB lift-out process, highlighting recent methodological advances that address the most common failure points of the technique, such as needle attachment, lift-out and transfer, and final thinning.
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Affiliation(s)
- Daniel M Long
- Sandia National Laboratories, Albuquerque, NM 87123, United States of America
| | - Manish Kumar Singh
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545, United States of America
| | - Kathryn A Small
- Sandia National Laboratories, Albuquerque, NM 87123, United States of America
| | - John Watt
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545, United States of America
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12
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Egu DT, Schmitt T, Waschke J. Mechanisms Causing Acantholysis in Pemphigus-Lessons from Human Skin. Front Immunol 2022; 13:884067. [PMID: 35720332 PMCID: PMC9205406 DOI: 10.3389/fimmu.2022.884067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 04/12/2022] [Indexed: 11/13/2022] Open
Abstract
Pemphigus vulgaris (PV) is an autoimmune bullous skin disease caused primarily by autoantibodies (PV-IgG) against the desmosomal adhesion proteins desmoglein (Dsg)1 and Dsg3. PV patient lesions are characterized by flaccid blisters and ultrastructurally by defined hallmarks including a reduction in desmosome number and size, formation of split desmosomes, as well as uncoupling of keratin filaments from desmosomes. The pathophysiology underlying the disease is known to involve several intracellular signaling pathways downstream of PV-IgG binding. Here, we summarize our studies in which we used transmission electron microscopy to characterize the roles of signaling pathways in the pathogenic effects of PV-IgG on desmosome ultrastructure in a human ex vivo skin model. Blister scores revealed inhibition of p38MAPK, ERK and PLC/Ca2+ to be protective in human epidermis. In contrast, inhibition of Src and PKC, which were shown to be protective in cell cultures and murine models, was not effective for human skin explants. The ultrastructural analysis revealed that for preventing skin blistering at least desmosome number (as modulated by ERK) or keratin filament insertion (as modulated by PLC/Ca2+) need to be ameliorated. Other pathways such as p38MAPK regulate desmosome number, size, and keratin insertion indicating that they control desmosome assembly and disassembly on different levels. Taken together, studies in human skin delineate target mechanisms for the treatment of pemphigus patients. In addition, ultrastructural analysis supports defining the specific role of a given signaling molecule in desmosome turnover at ultrastructural level.
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13
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Neel BL, Nisler CR, Walujkar S, Araya-Secchi R, Sotomayor M. Collective mechanical responses of cadherin-based adhesive junctions as predicted by simulations. Biophys J 2022; 121:991-1012. [PMID: 35150618 PMCID: PMC8943820 DOI: 10.1016/j.bpj.2022.02.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 01/02/2022] [Accepted: 02/07/2022] [Indexed: 12/13/2022] Open
Abstract
Cadherin-based adherens junctions and desmosomes help stabilize cell-cell contacts with additional function in mechano-signaling, while clustered protocadherin junctions are responsible for directing neuronal circuits assembly. Structural models for adherens junctions formed by epithelial cadherin (CDH1) proteins indicate that their long, curved ectodomains arrange to form a periodic, two-dimensional lattice stabilized by tip-to-tip trans interactions (across junction) and lateral cis contacts. Less is known about the exact architecture of desmosomes, but desmoglein (DSG) and desmocollin (DSC) cadherin proteins are also thought to form ordered junctions. In contrast, clustered protocadherin (PCDH)-based cell-cell contacts in neuronal tissues are thought to be responsible for self-recognition and avoidance, and structural models for clustered PCDH junctions show a linear arrangement in which their long and straight ectodomains form antiparallel overlapped trans complexes. Here, we report all-atom molecular dynamics simulations testing the mechanics of minimalistic adhesive junctions formed by CDH1, DSG2 coupled to DSC1, and PCDHγB4, with systems encompassing up to 3.7 million atoms. Simulations generally predict a favored shearing pathway for the adherens junction model and a two-phased elastic response to tensile forces for the adhesive adherens junction and the desmosome models. Complexes within these junctions first unbend at low tensile force and then become stiff to unbind without unfolding. However, cis interactions in both the CDH1 and DSG2-DSC1 systems dictate varied mechanical responses of individual dimers within the junctions. Conversely, the clustered protocadherin PCDHγB4 junction lacks a distinct two-phased elastic response. Instead, applied tensile force strains trans interactions directly, as there is little unbending of monomers within the junction. Transient intermediates, influenced by new cis interactions, are observed after the main rupture event. We suggest that these collective, complex mechanical responses mediated by cis contacts facilitate distinct functions in robust cell-cell adhesion for classical cadherins and in self-avoidance signaling for clustered PCDHs.
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Affiliation(s)
- Brandon L Neel
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio; The Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio
| | - Collin R Nisler
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio; Biophysics Graduate Program, The Ohio State University, Columbus, Ohio
| | - Sanket Walujkar
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio; Chemical Physics Graduate Program, The Ohio State University, Columbus, Ohio
| | - Raul Araya-Secchi
- Facultad de Ingenieria y Tecnologia, Universidad San Sebastian, Santiago, Chile
| | - Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio; The Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio; Biophysics Graduate Program, The Ohio State University, Columbus, Ohio; Chemical Physics Graduate Program, The Ohio State University, Columbus, Ohio.
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14
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Yeruva S, Waschke J. Structure and regulation of desmosomes in intercalated discs: Lessons from epithelia. J Anat 2022; 242:81-90. [PMID: 35128661 PMCID: PMC9773171 DOI: 10.1111/joa.13634] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 12/22/2021] [Accepted: 01/10/2022] [Indexed: 12/25/2022] Open
Abstract
For electromechanical coupling of cardiomyocytes, intercalated discs (ICDs) are pivotal as highly specialized intercellular contact areas. ICD consists of adhesive contacts, such as desmosomes and adherens junctions (AJs) that are partially intermingled and thereby form an area composita to provide mechanical strength, as well as gap junctions (GJ) and sodium channels for excitation propagation. In contrast, in epithelia, mixed junctions with features of desmosomes and AJs are regarded as transitory primarily during the formation of desmosomes. The anatomy of desmosomes is defined by a typical ultrastructure with dense intracellular plaques anchoring the cadherin-type adhesion molecules to the intermediate filament cytoskeleton. Desmosomal diseases characterized by impaired adhesive and signalling functions of desmosomal contacts lead to arrhythmogenic cardiomyopathy when affecting cardiomyocytes and cause pemphigus when manifesting in keratinocytes or present as cardiocutaneous syndromes when both cell types are targeted by the disease, which underscores the high biomedical relevance of these cell contacts. Therefore, comparative analyses regarding the structure and regulation of desmosomal contacts in cardiomyocytes and epithelial cells are helpful to better understand disease pathogenesis. In this brief review, we describe the structural properties of ICD compared to epithelial desmosomes and suggest that mechanisms regulating adhesion may at least in part be comparable. Also, we discuss whether phenomena such as hyperadhesion or the bidirectional regulation of desmosomes to serve as signalling hubs in epithelial cells may also be relevant for ICD.
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Affiliation(s)
- Sunil Yeruva
- Ludwig‐Maximilian‐Universität München, Anatomische Anstalt, Lehrstuhl Anatomie I – Vegetative AnatomieMunichGermany
| | - Jens Waschke
- Ludwig‐Maximilian‐Universität München, Anatomische Anstalt, Lehrstuhl Anatomie I – Vegetative AnatomieMunichGermany
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15
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Fülle JB, Huppert H, Liebl D, Liu J, Alves de Almeida R, Yanes B, Wright GD, Lane EB, Garrod DR, Ballestrem C. Desmosome dualism - most of the junction is stable, but a plakophilin moiety is persistently dynamic. J Cell Sci 2021; 134:272445. [PMID: 34635908 DOI: 10.1242/jcs.258906] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 10/05/2021] [Indexed: 01/06/2023] Open
Abstract
Desmosomes, strong cell-cell junctions of epithelia and cardiac muscle, link intermediate filaments to cell membranes and mechanically integrate cells across tissues, dissipating mechanical stress. They comprise five major protein classes - desmocollins and desmogleins (the desmosomal cadherins), plakoglobin, plakophilins and desmoplakin - whose individual contribution to the structure and turnover of desmosomes is poorly understood. Using live-cell imaging together with fluorescence recovery after photobleaching (FRAP) and fluorescence loss and localisation after photobleaching (FLAP), we show that desmosomes consist of two contrasting protein moieties or modules: a very stable moiety of desmosomal cadherins, desmoplakin and plakoglobin, and a highly mobile plakophilin (Pkp2a). As desmosomes mature from Ca2+ dependence to Ca2+-independent hyper-adhesion, their stability increases, but Pkp2a remains highly mobile. We show that desmosome downregulation during growth-factor-induced cell scattering proceeds by internalisation of whole desmosomes, which still retain a stable moiety and highly mobile Pkp2a. This molecular mobility of Pkp2a suggests a transient and probably regulatory role for Pkp2a in desmosomes. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Judith B Fülle
- Wellcome Trust Centre for Cell-Matrix Research, University of Manchester, Manchester M13 9PT, UK.,Skin Research Institute of Singapore, Agency of Science Technology and Research (A*STAR), 8A Biomedical Grove, #06-06 Immunos, 138648 Singapore, Singapore
| | - Henri Huppert
- Wellcome Trust Centre for Cell-Matrix Research, University of Manchester, Manchester M13 9PT, UK.,Institute of Medical Biology, Agency of Science Technology and Research (A*STAR), 61 Biopolis Dr, 138673 Singapore, Singapore
| | - David Liebl
- A*STAR Microscopy Platform, Research Support Centre, Agency of Science Technology and Research (A*STAR), Biopolis 138673 Singapore, Singapore
| | - Jaron Liu
- Institute of Medical Biology, Agency of Science Technology and Research (A*STAR), 61 Biopolis Dr, 138673 Singapore, Singapore
| | - Rogerio Alves de Almeida
- Wellcome Trust Centre for Cell-Matrix Research, University of Manchester, Manchester M13 9PT, UK
| | - Bian Yanes
- Wellcome Trust Centre for Cell-Matrix Research, University of Manchester, Manchester M13 9PT, UK
| | - Graham D Wright
- Skin Research Institute of Singapore, Agency of Science Technology and Research (A*STAR), 8A Biomedical Grove, #06-06 Immunos, 138648 Singapore, Singapore.,A*STAR Microscopy Platform, Research Support Centre, Agency of Science Technology and Research (A*STAR), Biopolis 138673 Singapore, Singapore
| | - E Birgitte Lane
- Skin Research Institute of Singapore, Agency of Science Technology and Research (A*STAR), 8A Biomedical Grove, #06-06 Immunos, 138648 Singapore, Singapore
| | - David R Garrod
- Wellcome Trust Centre for Cell-Matrix Research, University of Manchester, Manchester M13 9PT, UK
| | - Christoph Ballestrem
- Wellcome Trust Centre for Cell-Matrix Research, University of Manchester, Manchester M13 9PT, UK
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16
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Vite A, Gandjbakhch E, Hery T, Fressart V, Gary F, Simon F, Varnous S, Hidden Lucet F, Charron P, Villard E. Desmoglein-2 mutations in propeptide cleavage-site causes arrhythmogenic right ventricular cardiomyopathy/dysplasia by impairing extracellular 1-dependent desmosomal interactions upon cellular stress. Europace 2021; 22:320-329. [PMID: 31845994 DOI: 10.1093/europace/euz329] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 11/18/2019] [Indexed: 02/04/2023] Open
Abstract
AIMS Desmoglein-2 (DSG2) mutations, which encode a heart-specific cadherin crucial for desmosomal adhesion, are frequent in arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D). DSG2 mutations have been associated with higher risk of biventricular involvement. Among DSG2 mutations, mutations of the inhibitory propeptide consensus cleavage-site (Arg-X-Arg/Lys-Arg), are particularly frequent. In the present work, we explored the functional consequences of DSG2 propeptide cleavage site mutations p.Arg49His, p.Arg46Trp, and p.Arg46Gln on localization, adhesive properties, and desmosome incorporation of DSG2. METHODS AND RESULTS We studied the expression of mutant-DSG2 in human heart and in epithelial and cardiac cellular models expressing wild-type or mutant (p.Arg49His, p.Arg46Trp, and p.Arg46Gln) proDSG2-GFP fusion proteins. The consequences of the p.Arg46Trp mutation on DSG2 adhesiveness were studied by surface plasmon resonance. Incorporation of mutant p.Arg46Trp DSG2 into desmosomes was studied under low-calcium culture conditions and cyclic mechanical stress. We demonstrated in human heart and cellular models that all three mutations prevented N-terminal propeptide cleavage, but did not modify intercellular junction targeting. Surface plasmon resonance experiments showed a propeptide-dependent loss of interaction between the cadherin N-terminal extracellular 1 (EC1) domains. Additionally, proDSG2 mutant proteins were abnormally incorporated into desmosomes under low-calcium culture conditions or following mechanical stress. This was accompanied by an epidermal growth factor receptor-dependent internalization of proDSG2, suggesting increased turnover of unprocessed proDSG2. CONCLUSION Our results strongly suggest weakened desmosomal adhesiveness due to abnormal incorporation of uncleaved mutant proDSG2 in cellular stress conditions. These results provide new insights into desmosomal cadherin regulation and ARVC/D pathophysiology, in particular, the potential role of mechanical stress on desmosomal dysfunction.
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Affiliation(s)
- Alexia Vite
- Sorbonne Université, Faculté de médecine Pitié-Salpêtrière, INSERM U1166, IHU ICAN, F-75013 Paris, France
| | - Estelle Gandjbakhch
- Sorbonne Université, Faculté de médecine Pitié-Salpêtrière, INSERM U1166, IHU ICAN, F-75013 Paris, France.,Département de Cardiologie, AP-HP, Groupe Hospitalier Pitié-Salpêtrière, Paris, France.,Centre de référence des maladies cardiaques héréditaires, AP-HP, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Tiphaine Hery
- Sorbonne Université, Faculté de médecine Pitié-Salpêtrière, INSERM U1166, IHU ICAN, F-75013 Paris, France
| | - Veronique Fressart
- Service de Biochimie Métabolique, AP-HP, Groupe Hospitalier Pitié-Salpêtrière, Unité de Cardiogénétique et Myogénétique, Paris, France
| | - Francoise Gary
- Sorbonne Université, Faculté de médecine Pitié-Salpêtrière, INSERM U1166, IHU ICAN, F-75013 Paris, France
| | - Francoise Simon
- Service de Biochimie Métabolique, AP-HP, Groupe Hospitalier Pitié-Salpêtrière, Unité de Cardiogénétique et Myogénétique, Paris, France
| | - Shaida Varnous
- Département de Chirurgie Cardio-thoracique, AP-HP, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | | | - Philippe Charron
- Sorbonne Université, Faculté de médecine Pitié-Salpêtrière, INSERM U1166, IHU ICAN, F-75013 Paris, France.,Département de Cardiologie, AP-HP, Groupe Hospitalier Pitié-Salpêtrière, Paris, France.,Centre de référence des maladies cardiaques héréditaires, AP-HP, Groupe Hospitalier Pitié-Salpêtrière, Paris, France.,Département de Génétique, AP-HP, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Eric Villard
- Sorbonne Université, Faculté de médecine Pitié-Salpêtrière, INSERM U1166, IHU ICAN, F-75013 Paris, France
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17
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Chowdhury D, Watters K, Biederer T. Synaptic recognition molecules in development and disease. Curr Top Dev Biol 2021; 142:319-370. [PMID: 33706921 DOI: 10.1016/bs.ctdb.2020.12.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Synaptic connectivity patterns underlie brain functions. How recognition molecules control where and when neurons form synapses with each other, therefore, is a fundamental question of cellular neuroscience. This chapter delineates adhesion and signaling complexes as well as secreted factors that contribute to synaptic partner recognition in the vertebrate brain. The sections follow a developmental perspective and discuss how recognition molecules (1) guide initial synaptic wiring, (2) provide for the rejection of incorrect partner choices, (3) contribute to synapse specification, and (4) support the removal of inappropriate synapses once formed. These processes involve a rich repertoire of molecular players and key protein families are described, notably the Cadherin and immunoglobulin superfamilies, Semaphorins/Plexins, Leucine-rich repeat containing proteins, and Neurexins and their binding partners. Molecular themes that diversify these recognition systems are defined and highlighted throughout the text, including the neuron-type specific expression and combinatorial action of recognition factors, alternative splicing, and post-translational modifications. Methodological innovations advancing the field such as proteomic approaches and single cell expression studies are additionally described. Further, the chapter highlights the importance of choosing an appropriate brain region to analyze synaptic recognition factors and the advantages offered by laminated structures like the hippocampus or retina. In a concluding section, the profound disease relevance of aberrant synaptic recognition for neurodevelopmental and psychiatric disorders is discussed. Based on the current progress, an outlook is presented on research goals that can further advance insights into how recognition molecules provide for the astounding precision and diversity of synaptic connections.
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Affiliation(s)
| | - Katherine Watters
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States; Neuroscience Graduate Program, Tufts University School of Medicine, Boston, MA, United States
| | - Thomas Biederer
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States.
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18
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Roth-Walter F, Adcock IM, Benito-Villalvilla C, Bianchini R, Bjermer L, Boyman O, Caramori G, Cari L, Fan Chung K, Diamant Z, Eguiluz-Gracia I, Knol EF, Kolios A, Levi-Schaffer F, Nocentini G, Palomares O, Redegeld F, Van Esch B, Stellato C. Immune modulation via T regulatory cell enhancement: Disease-modifying therapies for autoimmunity and their potential for chronic allergic and inflammatory diseases-An EAACI position paper of the Task Force on Immunopharmacology (TIPCO). Allergy 2021; 76:90-113. [PMID: 32593226 DOI: 10.1111/all.14478] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 06/09/2020] [Accepted: 06/18/2020] [Indexed: 12/13/2022]
Abstract
Therapeutic advances using targeted biologicals and small-molecule drugs have achieved significant success in the treatment of chronic allergic, autoimmune, and inflammatory diseases particularly for some patients with severe, treatment-resistant forms. This has been aided by improved identification of disease phenotypes. Despite these achievements, not all severe forms of chronic inflammatory and autoimmune diseases are successfully targeted, and current treatment options, besides allergen immunotherapy for selected allergic diseases, fail to change the disease course. T cell-based therapies aim to cure diseases through the selective induction of appropriate immune responses following the delivery of engineered, specific cytotoxic, or regulatory T cells (Tregs). Adoptive cell therapies (ACT) with genetically engineered T cells have revolutionized the oncology field, bringing curative treatment for leukemia and lymphoma, while therapies exploiting the suppressive functions of Tregs have been developed in nononcological settings, such as in transplantation and autoimmune diseases. ACT with Tregs are also being considered in nononcological settings such as cardiovascular disease, obesity, and chronic inflammatory disorders. After describing the general features of T cell-based approaches and current applications in autoimmune diseases, this position paper reviews the experimental models testing or supporting T cell-based approaches, especially Treg-based approaches, in severe IgE-mediated responses and chronic respiratory airway diseases, such as severe asthma and COPD. Along with an assessment of challenges and unmet needs facing the application of ACT in these settings, this article underscores the potential of ACT to offer curative options for patients with severe or treatment-resistant forms of these immune-driven disorders.
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Affiliation(s)
- Franziska Roth-Walter
- Comparative Medicine, The Interuniversity Messerli Research Institute of the University of Veterinary Medicine Vienna, Medical University Vienna and University Vienna, Vienna, Austria
| | - Ian M Adcock
- Molecular Cell Biology Group, National Heart & Lung Institute, Imperial College London, London, UK
| | - Cristina Benito-Villalvilla
- Department of Biochemistry and Molecular Biology, School of Chemistry, Complutense University of Madrid, Madrid, Spain
| | - Rodolfo Bianchini
- Comparative Medicine, The Interuniversity Messerli Research Institute of the University of Veterinary Medicine Vienna, Medical University Vienna and University Vienna, Vienna, Austria
| | - Leif Bjermer
- Department of Respiratory Medicine and Allergology, Lung and Allergy research, Allergy, Asthma and COPD Competence Center, Lund University, Lund, Sweden
| | - Onur Boyman
- Department of Immunology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Gaetano Caramori
- Department of Biomedical Sciences, Dentistry and Morphological and Functional Imaging (BIOMORF), Respiratory Medicine Unit, University of Messina, Messina, Italy
| | - Luigi Cari
- Department of Medicine, Section of Pharmacology, University of Perugia, Perugia, Italy
| | - Kian Fan Chung
- Experimental Studies Medicine at National Heart & Lung Institute, Imperial College London & Royal Brompton & Harefield NHS Trust, London, UK
| | - Zuzana Diamant
- Department of Respiratory Medicine and Allergology, Institute for Clinical Science, Skane University Hospital, Lund, Sweden
- Department of Respiratory Medicine, First Faculty of Medicine, Charles University and Thomayer Hospital, Prague, Czech Republic
- Department of Clinical Pharmacy & Pharmacology, University Groningen, University Medical Center Groningen and QPS-NL, Groningen, Netherlands
| | - Ibon Eguiluz-Gracia
- Allergy Unit, Hospital Regional Universitario de Málaga-Instituto de Investigación Biomédica de Málaga (IBIMA)-ARADyAL, Málaga, Spain
| | - Edward F Knol
- Departments of Immunology and Dermatology/Allergology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Antonios Kolios
- Department of Immunology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Francesca Levi-Schaffer
- Pharmacology Unit, Faculty of Medicine, Institute for Drug Research, The Hebrew University of Jerusalem, Israel
| | - Giuseppe Nocentini
- Department of Medicine, Section of Pharmacology, University of Perugia, Perugia, Italy
| | - Oscar Palomares
- Department of Biochemistry and Molecular Biology, School of Chemistry, Complutense University of Madrid, Madrid, Spain
| | - Frank Redegeld
- Faculty of Science, Division of Pharmacology, Department of Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
| | - Betty Van Esch
- Faculty of Science, Division of Pharmacology, Department of Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
| | - Cristiana Stellato
- Department of Medicine, Surgery and Dentistry "Scuola Medica Salernitana", University of Salerno, Salerno, Italy
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19
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Desmosome architecture derived from molecular dynamics simulations and cryo-electron tomography. Proc Natl Acad Sci U S A 2020; 117:27132-27140. [PMID: 33067392 PMCID: PMC7959525 DOI: 10.1073/pnas.2004563117] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The desmosome is a major cell–cell junction connecting cells in tissues under high mechanical load. Currently, while structures of the constituent cadherins are known, the desmosome architecture has remained elusive. The primary reason is the high plasticity of the cadherins. As many other cellular structures, their high flexibility cannot be easily addressed by conventional structural techniques that rely on averaging many identical structures. For this, we combine high-end cryo-electron tomography with large-scale molecular dynamics simulations to produce a molecular model of the desmosome that integrates new with decades-old observations, accounts for the remarkable biophysical properties, and maps the intermolecular interactions. Desmosomes are cell–cell junctions that link tissue cells experiencing intense mechanical stress. Although the structure of the desmosomal cadherins is known, the desmosome architecture—which is essential for mediating numerous functions—remains elusive. Here, we recorded cryo-electron tomograms (cryo-ET) in which individual cadherins can be discerned; they appear variable in shape, spacing, and tilt with respect to the membrane. The resulting sub-tomogram average reaches a resolution of ∼26 Å, limited by the inherent flexibility of desmosomes. To address this challenge typical of dynamic biological assemblies, we combine sub-tomogram averaging with atomistic molecular dynamics (MD) simulations. We generate models of possible cadherin arrangements and perform an in silico screening according to biophysical and structural properties extracted from MD simulation trajectories. We find a truss-like arrangement of cadherins that resembles the characteristic footprint seen in the electron micrograph. The resulting model of the desmosomal architecture explains their unique biophysical properties and strength.
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20
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Affiliation(s)
- Wanda Kukulski
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, 3012 Bern, Switzerland.
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21
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Ganeva I, Kukulski W. Membrane Architecture in the Spotlight of Correlative Microscopy. Trends Cell Biol 2020; 30:577-587. [DOI: 10.1016/j.tcb.2020.04.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 03/27/2020] [Accepted: 04/01/2020] [Indexed: 12/19/2022]
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22
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Böhning J, Bharat TAM. Towards high-throughput in situ structural biology using electron cryotomography. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 160:97-103. [PMID: 32579969 DOI: 10.1016/j.pbiomolbio.2020.05.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 05/21/2020] [Accepted: 05/27/2020] [Indexed: 01/11/2023]
Abstract
Electron cryotomography is a rapidly evolving method for imaging macromolecules directly within the native environment of cells and tissues. Combined with sub-tomogram averaging, it allows structural and cell biologists to obtain sub-nanometre resolution structures in situ. However, low throughput in cryo-ET sample preparation and data acquisition, as well as difficulties in target localisation and sub-tomogram averaging image processing, limit its widespread usability. In this review, we discuss new advances in the field that address these throughput and technical problems. We focus on recent efforts made to resolve issues in sample thinning, improvement in data collection speed at the microscope, strategies for localisation of macromolecules using correlated light and electron microscopy and advancements made to improve resolution in sub-tomogram averaging. These advances will considerably decrease the amount of time and effort required for cryo-ET and sub-tomogram averaging, ushering in a new era of structural biology where in situ macromolecular structure determination will be routine.
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Affiliation(s)
- Jan Böhning
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, United Kingdom; Central Oxford Structural Microscopy and Imaging Centre, South Parks Road, Oxford OX1 3RE, United Kingdom
| | - Tanmay A M Bharat
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, United Kingdom; Central Oxford Structural Microscopy and Imaging Centre, South Parks Road, Oxford OX1 3RE, United Kingdom.
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23
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Bartle EI, Rao TC, Beggs RR, Dean WF, Urner TM, Kowalczyk AP, Mattheyses AL. Protein exchange is reduced in calcium-independent epithelial junctions. J Cell Biol 2020; 219:151763. [PMID: 32399559 PMCID: PMC7265307 DOI: 10.1083/jcb.201906153] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Revised: 01/29/2020] [Accepted: 03/11/2020] [Indexed: 12/29/2022] Open
Abstract
Desmosomes are cell–cell junctions that provide mechanical integrity to epithelial and cardiac tissues. Desmosomes have two distinct adhesive states, calcium-dependent and hyperadhesive, which balance tissue plasticity and strength. A highly ordered array of cadherins in the adhesive interface is hypothesized to drive hyperadhesion, but how desmosome structure confers adhesive state is still elusive. We employed fluorescence polarization microscopy to show that cadherin order is not required for hyperadhesion induced by pharmacologic and genetic approaches. FRAP experiments in cells treated with the PKCα inhibitor Gö6976 revealed that cadherins, plakoglobin, and desmoplakin have significantly reduced exchange in and out of hyperadhesive desmosomes. To test whether this was a result of enhanced keratin association, we used the desmoplakin mutant S2849G, which conferred reduced protein exchange. We propose that inside-out regulation of protein exchange modulates adhesive function, whereby proteins are “locked in” to hyperadhesive desmosomes while protein exchange confers plasticity on calcium-dependent desmosomes, thereby providing rapid control of adhesion.
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Affiliation(s)
- Emily I Bartle
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL
| | - Tejeshwar C Rao
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL
| | - Reena R Beggs
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL
| | - William F Dean
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL
| | - Tara M Urner
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL
| | - Andrew P Kowalczyk
- Departments of Cell Biology and Dermatology, Emory University, Atlanta, GA
| | - Alexa L Mattheyses
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL
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24
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Ng CT, Gan L. Investigating eukaryotic cells with cryo-ET. Mol Biol Cell 2020; 31:87-100. [PMID: 31935172 PMCID: PMC6960407 DOI: 10.1091/mbc.e18-05-0329] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 11/25/2019] [Accepted: 11/29/2019] [Indexed: 01/06/2023] Open
Abstract
The interior of eukaryotic cells is mysterious. How do the large communities of macromolecular machines interact with each other? How do the structures and positions of these nanoscopic entities respond to new stimuli? Questions like these can now be answered with the help of a method called electron cryotomography (cryo-ET). Cryo-ET will ultimately reveal the inner workings of a cell at the protein, secondary structure, and perhaps even side-chain levels. Combined with genetic or pharmacological perturbation, cryo-ET will allow us to answer previously unimaginable questions, such as how structure, biochemistry, and forces are related in situ. Because it bridges structural biology and cell biology, cryo-ET is indispensable for structural cell biology-the study of the 3-D macromolecular structure of cells. Here we discuss some of the key ideas, strategies, auxiliary techniques, and innovations that an aspiring structural cell biologist will consider when planning to ask bold questions.
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Affiliation(s)
- Cai Tong Ng
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore 117543
| | - Lu Gan
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore 117543
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25
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A. Abd El Samad A. Transmission Electron Tomography: Intracellular Insight for the Future of Medicine. ELECTRON MICROSCOPY - NOVEL MICROSCOPY TRENDS 2019. [DOI: 10.5772/intechopen.84977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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26
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Winklbauer R. Dynamic cell–cell adhesion mediated by pericellular matrix interaction – a hypothesis. J Cell Sci 2019; 132:132/16/jcs231597. [DOI: 10.1242/jcs.231597] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
ABSTRACT
Cell–cell adhesion strength, measured as tissue surface tension, spans an enormous 1000-fold range when different cell types are compared. However, the examination of basic mechanical principles of cell adhesion indicates that cadherin-based and related mechanisms are not able to promote the high-strength adhesion experimentally observed in many late embryonic or malignant tissues. Therefore, the hypothesis is explored that the interaction of the pericellular matrices of cells generates strong adhesion by a mechanism akin to the self-adhesion/self-healing of dynamically cross-linked hydrogels. Quantitative data from biofilm matrices support this model. The mechanism links tissue surface tension to pericellular matrix stiffness. Moreover, it explains the wide, matrix-filled spaces around cells in liquid-like, yet highly cohesive, tissues, and it rehabilitates aspects of the original interpretation of classical cell sorting experiments, as expressed in Steinberg's differential adhesion hypothesis: that quantitative differences in adhesion energies between cells are sufficient to drive sorting.
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Affiliation(s)
- Rudolf Winklbauer
- Department of Cell and Systems Biology, University of Toronto, 25 Harbord Street, Toronto, Ontario, M5S 3G5, Canada
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27
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Balachandran VS, Divya KP, Samateh M, Sagiri SS, Satapathy S, Pradhan P, Raghavan SR, Rakesh L, Sellers MS, Karna SP, John G. Freestanding organogels by molecular velcro of unsaturated amphiphiles. SOFT MATTER 2019; 15:6263-6268. [PMID: 31312826 DOI: 10.1039/c9sm00378a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A simple amphiphile, N-cardanyltaurine amide (NCT) with different degrees of cis-unsaturation in its tail resulted in the formation of strong organogels. Interestingly, this is in contrast to the commonly accepted notion that introducing unsaturation in alkyl chains enhances fluidity in lipid assemblies. The physico-chemical and first-principles DFT calculations confirmed the pegging of 'kinked' unsaturated side chains, where the hydrophobic interlocking as in Velcro fasteners leads to a network of cylindrical micelles, resulting in self-standing organogels. Textural profile analysis and spectroscopic details substantiated the dynamic assembly to resemble a 3D network of gelators rather than being a cross-linked or polymerized matrix of monomers.
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Affiliation(s)
- Vijai Shankar Balachandran
- Department of Chemistry and Biochemistry and Center for Discovery and Innovation, The City College of New York, 85 St. Nicholas Terrace, New York, NY 10031, USA.
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28
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Abstract
Cryo-electron tomography (cryo-ET) allows three-dimensional (3D) visualization of frozen-hydrated biological samples, such as protein complexes and cell organelles, in near-native environments at nanometer scale. Protein complexes that are present in multiple copies in a set of tomograms can be extracted, mutually aligned, and averaged to yield a signal-enhanced 3D structure up to sub-nanometer or even near-atomic resolution. This technique, called subtomogram averaging (StA), is powered by improvements in EM hardware and image processing software. Importantly, StA provides unique biological insights into the structure and function of cellular machinery in close-to-native contexts. In this chapter, we describe the principles and key steps of StA. We briefly cover sample preparation and data collection with an emphasis on image processing procedures related to tomographic reconstruction, subtomogram alignment, averaging, and classification. We conclude by summarizing current limitations and future directions of this technique with a focus on high-resolution StA.
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29
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Lewis JD, Caldara AL, Zimmer SE, Stahley SN, Seybold A, Strong NL, Frangakis AS, Levental I, Wahl JK, Mattheyses AL, Sasaki T, Nakabayashi K, Hata K, Matsubara Y, Ishida-Yamamoto A, Amagai M, Kubo A, Kowalczyk AP. The desmosome is a mesoscale lipid raft-like membrane domain. Mol Biol Cell 2019; 30:1390-1405. [PMID: 30943110 PMCID: PMC6724694 DOI: 10.1091/mbc.e18-10-0649] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Desmogleins (Dsgs) are cadherin family adhesion molecules essential for epidermal integrity. Previous studies have shown that desmogleins associate with lipid rafts, but the significance of this association was not clear. Here, we report that the desmoglein transmembrane domain (TMD) is the primary determinant of raft association. Further, we identify a novel mutation in the DSG1 TMD (G562R) that causes severe dermatitis, multiple allergies, and metabolic wasting syndrome. Molecular modeling predicts that this G-to-R mutation shortens the DSG1 TMD, and experiments directly demonstrate that this mutation compromises both lipid raft association and desmosome incorporation. Finally, cryo-electron tomography indicates that the lipid bilayer within the desmosome is ∼10% thicker than adjacent regions of the plasma membrane. These findings suggest that differences in bilayer thickness influence the organization of adhesion molecules within the epithelial plasma membrane, with cadherin TMDs recruited to the desmosome via the establishment of a specialized mesoscale lipid raft-like membrane domain.
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Affiliation(s)
- Joshua D Lewis
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322.,Department of Graduate Program in Biochemistry, Cell and Developmental Biology, Emory University School of Medicine, Atlanta, GA 30322
| | - Amber L Caldara
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322.,Department of Graduate Program in Cancer Biology, Emory University School of Medicine, Atlanta, GA 30322
| | - Stephanie E Zimmer
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322.,Department of Graduate Program in Biochemistry, Cell and Developmental Biology, Emory University School of Medicine, Atlanta, GA 30322
| | - Sara N Stahley
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322.,Department of Graduate Program in Biochemistry, Cell and Developmental Biology, Emory University School of Medicine, Atlanta, GA 30322
| | - Anna Seybold
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, 60323 Frankfurt, Germany.,Institute for Biophysics, Goethe University Frankfurt, 60323 Frankfurt, Germany
| | - Nicole L Strong
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322
| | - Achilleas S Frangakis
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, 60323 Frankfurt, Germany.,Institute for Biophysics, Goethe University Frankfurt, 60323 Frankfurt, Germany
| | - Ilya Levental
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX 77030
| | - James K Wahl
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, NE 68583
| | - Alexa L Mattheyses
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Takashi Sasaki
- Center for Supercentenarian Medical Research, Keio University School of Medicine, Tokyo 160-8582, Japan
| | | | - Kenichiro Hata
- National Research Institute for Child Health and Development, Tokyo, Japan
| | - Yoichi Matsubara
- National Research Institute for Child Health and Development, Tokyo, Japan
| | - Akemi Ishida-Yamamoto
- Department of Dermatology, Asahikawa Medical University, Asahikawa, Hokkaido 078-8510, Japan
| | - Masayuki Amagai
- Department of Dermatology, Keio University School of Medicine, Tokyo 160-8582, Japan
| | - Akiharu Kubo
- Department of Dermatology, Keio University School of Medicine, Tokyo 160-8582, Japan
| | - Andrew P Kowalczyk
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322.,Department of Dermatology, Emory University School of Medicine, Atlanta, GA 30322.,Department of Graduate Program in Biochemistry, Cell and Developmental Biology, Emory University School of Medicine, Atlanta, GA 30322.,Department of Graduate Program in Cancer Biology, Emory University School of Medicine, Atlanta, GA 30322
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30
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CryoEM structure of adenovirus type 3 fibre with desmoglein 2 shows an unusual mode of receptor engagement. Nat Commun 2019; 10:1181. [PMID: 30862836 PMCID: PMC6414520 DOI: 10.1038/s41467-019-09220-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 02/26/2019] [Indexed: 11/09/2022] Open
Abstract
Attachment of human adenovirus (HAd) to the host cell is a critical step of infection. Initial attachment occurs via the adenoviral fibre knob protein and a cellular receptor. Here we report the cryo-electron microscopy (cryo-EM) structure of a <100 kDa non-symmetrical complex comprising the trimeric HAd type 3 fibre knob (HAd3K) and human desmoglein 2 (DSG2). The structure reveals a unique stoichiometry of 1:1 and 2:1 (DSG2: knob trimer) not previously observed for other HAd-receptor complexes. We demonstrate that mutating Asp261 in the fibre knob is sufficient to totally abolish receptor binding. These data shed new light on adenovirus infection strategies and provide insights for adenoviral vector development and structure-based design.
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31
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Lu CS, Lee YN, Wang SW, Wu YJ, Su CH, Hsieh CL, Tien TY, Wang BJ, Chen MC, Chen CW, Yeh HI. KC21 Peptide Inhibits Angiogenesis and Attenuates Hypoxia-Induced Retinopathy. J Cardiovasc Transl Res 2019; 12:366-377. [PMID: 30790141 PMCID: PMC6707963 DOI: 10.1007/s12265-019-09865-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 01/20/2019] [Indexed: 12/31/2022]
Abstract
Desmogleins (Dsg2) are the major components of desmosomes. Dsg2 has five extracellular tandem cadherin domains (EC1-EC5) for cell-cell interaction. We had previously confirmed the Dsg2 antibody and its epitope (named KC21) derived from EC2 domain suppressing epithelial-mesenchymal transition and invasion in human cancer cell lines. Here, we screened six peptide fragments derived from EC2 domain and found that KR20, the parental peptide of KC21, was the most potent one on suppressing endothelial colony-forming cell (ECFC) tube-like structure formation. KC21 peptide also attenuated migration but did not disrupt viability and proliferation of ECFCs, consistent with the function to inhibit VEGF-mediated activation of p38 MAPK but not AKT and ERK. Animal studies showed that KC21 peptides suppressed capillary growth in Matrigel implant assay and inhibited oxygen-induced retinal neovascularization. The effects were comparable to bevacizumab (Bev). In conclusion, KC21 peptide is an angiogenic inhibitor potentially useful for treating angiogenesis-related diseases.
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Affiliation(s)
- Chi-Sheng Lu
- Departments of Medical Research, Mackay Memorial Hospital, Taipei, 10449, Taiwan.,Virginia Contract Research Organization Co., Ltd, Taipei, 11491, Taiwan
| | - Yi-Nan Lee
- Departments of Medical Research, Mackay Memorial Hospital, Taipei, 10449, Taiwan
| | - Shin-Wei Wang
- Department of Medicine, Mackay Medical College, New Taipei City, 25245, Taiwan
| | - Yih-Jer Wu
- Departments of Medical Research, Mackay Memorial Hospital, Taipei, 10449, Taiwan.,Department of Medicine, Mackay Medical College, New Taipei City, 25245, Taiwan
| | - Cheng-Huang Su
- Departments of Medical Research, Mackay Memorial Hospital, Taipei, 10449, Taiwan
| | - Chin-Ling Hsieh
- Departments of Medical Research, Mackay Memorial Hospital, Taipei, 10449, Taiwan
| | - Ting Yi Tien
- Departments of Medical Research, Mackay Memorial Hospital, Taipei, 10449, Taiwan
| | - Bo-Jeng Wang
- Department of Medicine, Mackay Medical College, New Taipei City, 25245, Taiwan
| | - Min-Che Chen
- Asclepiumm Taiwan Co., Ltd, New Taipei City, 25160, Taiwan
| | - Chun-Wei Chen
- Asclepiumm Taiwan Co., Ltd, New Taipei City, 25160, Taiwan
| | - Hung-I Yeh
- Departments of Medical Research, Mackay Memorial Hospital, Taipei, 10449, Taiwan. .,Department of Medicine, Mackay Medical College, New Taipei City, 25245, Taiwan. .,Departments of Medical Research and Internal Medicine, Mackay Memorial Hospital, No. 92, Sec. 2, Zhongshan N. Rd, Taipei City, 10449, Taiwan.
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32
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Weber MS, Wojtynek M, Medalia O. Cellular and Structural Studies of Eukaryotic Cells by Cryo-Electron Tomography. Cells 2019; 8:E57. [PMID: 30654455 PMCID: PMC6356268 DOI: 10.3390/cells8010057] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 01/09/2019] [Accepted: 01/10/2019] [Indexed: 11/23/2022] Open
Abstract
The architecture of protein assemblies and their remodeling during physiological processes is fundamental to cells. Therefore, providing high-resolution snapshots of macromolecular complexes in their native environment is of major importance for understanding the molecular biology of the cell. Cellular structural biology by means of cryo-electron tomography (cryo-ET) offers unique insights into cellular processes at an unprecedented resolution. Recent technological advances have enabled the detection of single impinging electrons and improved the contrast of electron microscopic imaging, thereby significantly increasing the sensitivity and resolution. Moreover, various sample preparation approaches have paved the way to observe every part of a eukaryotic cell, and even multicellular specimens, under the electron beam. Imaging of macromolecular machineries at high resolution directly within their native environment is thereby becoming reality. In this review, we discuss several sample preparation and labeling techniques that allow the visualization and identification of macromolecular assemblies in situ, and demonstrate how these methods have been used to study eukaryotic cellular landscapes.
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Affiliation(s)
- Miriam Sarah Weber
- Department of Biochemistry, University of Zürich, 8057 Zürich, Switzerland.
| | - Matthias Wojtynek
- Department of Biochemistry, University of Zürich, 8057 Zürich, Switzerland.
- Department of Biology, Institute of Biochemistry, ETH Zürich, 8093 Zürich, Switzerland.
| | - Ohad Medalia
- Department of Biochemistry, University of Zürich, 8057 Zürich, Switzerland.
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva 84120, Israel.
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33
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Heymann JB, Vijayasarathy C, Huang RK, Dearborn AD, Sieving PA, Steven AC. Cryo-EM of retinoschisin branched networks suggests an intercellular adhesive scaffold in the retina. J Cell Biol 2019; 218:1027-1038. [PMID: 30630865 PMCID: PMC6400569 DOI: 10.1083/jcb.201806148] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 11/06/2018] [Accepted: 12/07/2018] [Indexed: 12/26/2022] Open
Abstract
Mutations in the essential retinal protein retinoschisin (RS1) cause a form of macular degeneration. Heymann et al. use cryo-EM to show that RS1 assembles into branched networks that may play a stabilizing role in maintaining the integrity of the retina. Mutations in the retinal protein retinoschisin (RS1) cause progressive loss of vision in young males, a form of macular degeneration called X-linked retinoschisis (XLRS). We previously solved the structure of RS1, a 16-mer composed of paired back-to-back octameric rings. Here, we show by cryo–electron microscopy that RS1 16-mers can assemble into extensive branched networks. We classified the different configurations, finding four types of interaction between the RS1 molecules. The predominant configuration is a linear strand with a wavy appearance. Three less frequent types constitute the branch points of the network. In all cases, the “spikes” around the periphery of the double rings are involved in these interactions. In the linear strand, a loop (usually referred to as spike 1) occurs on both sides of the interface between neighboring molecules. Mutations in this loop suppress secretion, indicating the possibility of intracellular higher-order assembly. These observations suggest that branched networks of RS1 may play a stabilizing role in maintaining the integrity of the retina.
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Affiliation(s)
- J Bernard Heymann
- Laboratory for Structural Biology Research, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD
| | - Camasamudram Vijayasarathy
- Section on Translational Research for Retinal and Macular Degeneration, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD
| | - Rick K Huang
- Cryo-Electron Microscopy Facility, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Altaira D Dearborn
- Laboratory for Structural Biology Research, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD
| | - Paul A Sieving
- Section on Translational Research for Retinal and Macular Degeneration, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD.,National Eye Institute, National Institutes of Health, Bethesda, MD
| | - Alasdair C Steven
- Laboratory for Structural Biology Research, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD
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34
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35
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Pfeffer S, Mahamid J. Unravelling molecular complexity in structural cell biology. Curr Opin Struct Biol 2018; 52:111-118. [PMID: 30339965 DOI: 10.1016/j.sbi.2018.08.009] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 06/18/2018] [Accepted: 08/29/2018] [Indexed: 12/14/2022]
Abstract
Structural and cell biology have traditionally been separate disciplines and employed techniques that were well defined within the realm of either one or the other. Recent technological breakthroughs propelled electron microscopy of frozen hydrated specimens (cryo-EM) followed by single-particle analysis (SPA) to become a widely applied approach for obtaining near-atomic resolution structures of purified macromolecules. In parallel, ongoing developments on sample preparation are increasingly successful in bringing molecular views into cell biology. Cryo-electron tomography (cryo-ET) has so far served as the main imaging modality employed in these efforts towards obtaining three-dimensional (3D) volumes of heterogeneous molecular assemblies. We review the state-of-the-art in cryo-ET and computational processing and describe the current opportunities and frontiers for in-cell applications.
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Affiliation(s)
- Stefan Pfeffer
- Centre for Molecular Biology of Heidelberg University (ZMBH), 69120 Heidelberg, Germany
| | - Julia Mahamid
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.
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36
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Affiliation(s)
- C Has
- Department of Dermatology, Medical Center - University of Freiburg, Faculty of Medicine, Hauptstrasse 7, 79104, Freiburg, Germany
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37
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Dutta M. Recent Advances in Single Particle Cryo-electron Microscopy and Cryo-electron Tomography to Determine the Structures of Biological Macromolecules. J Indian Inst Sci 2018. [DOI: 10.1007/s41745-018-0087-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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38
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Ultrastructural changes in endometrial desmosomes of desmoglein 2 mutant mice. Cell Tissue Res 2018; 374:317-327. [PMID: 29938327 DOI: 10.1007/s00441-018-2869-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 05/25/2018] [Indexed: 10/28/2022]
Abstract
The intercellular binding of desmosomal junctions is mediated by cadherins of the desmoglein (Dsg) and desmocollin (Dsc) type. Dsg2 mutant mice with deletion of a substantial segment of the extracellular EC1-EC2 domain, which is believed to participate in homo- and heterophilic desmosomal cadherin interactions, develop cardiac fibrosis and ventricular dilation. Widening of the intercellular cleft and complete intercalated disc ruptures can be observed in the hearts of these mice. Since a reduced litter size of homozygous Dsg2 mutant mice was noted and a functional correlation between desmosomes and embryo implantation has been deduced from animal studies, we looked for an alteration of desmosomes in uterine endometrial epithelium. Shape and number of desmosomes as well as the expression of Dsg2 and the desmosomal plaque protein desmoplakin (Dsp) were investigated by electron microscopy and immunohistochemistry in 12 oestrous-dated mice (7 wild type and 5 homozygous Dsg2 mutant mice) at the age of 9-17 weeks. The immunohistochemical detection of Dsg2 was diminished in the mutants and the number of desmosomes was significantly reduced as revealed by electron microscopy. In addition, the intercellular desmosomal space measured in electron micrographs was considerably widened in the Dsg2 mutants. The increased intercellular spacing can be explained by the partial deletion of the extracellular EC1-EC2 domain of Dsg2. Whether these changes explain the reduced number of offspring of homozygous Dsg2 mutant mice remains to be further investigated.
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39
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Fine details in complex environments: the power of cryo-electron tomography. Biochem Soc Trans 2018; 46:807-816. [PMID: 29934301 PMCID: PMC6103461 DOI: 10.1042/bst20170351] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 05/09/2018] [Accepted: 05/11/2018] [Indexed: 01/10/2023]
Abstract
Cryo-electron tomography (CET) is uniquely suited to obtain structural information from a wide range of biological scales, integrating and bridging knowledge from molecules to cells. In particular, CET can be used to visualise molecular structures in their native environment. Depending on the experiment, a varying degree of resolutions can be achieved, with the first near-atomic molecular structures becoming recently available. The power of CET has increased significantly in the last 5 years, in parallel with improvements in cryo-EM hardware and software that have also benefited single-particle reconstruction techniques. In this review, we cover the typical CET pipeline, starting from sample preparation, to data collection and processing, and highlight in particular the recent developments that support structural biology in situ. We provide some examples that highlight the importance of structure determination of molecules embedded within their native environment, and propose future directions to improve CET performance and accessibility.
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40
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Vodo D, O'Toole EA, Malchin N, Lahav A, Adir N, Sarig O, Green KJ, Smith FJD, Sprecher E. Striate palmoplantar keratoderma resulting from a missense mutation in DSG1. Br J Dermatol 2018; 179:755-757. [PMID: 29315490 DOI: 10.1111/bjd.16320] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- D Vodo
- Department of Dermatology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.,Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - E A O'Toole
- Centre for Cell Biology and Cutaneous Research, The Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, U.K
| | - N Malchin
- Department of Dermatology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - A Lahav
- Schulich Faculty of Chemistry, Technion, Haifa, Israel
| | - N Adir
- Schulich Faculty of Chemistry, Technion, Haifa, Israel
| | - O Sarig
- Department of Dermatology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - K J Green
- Departments of Pathology and Dermatology, Northwestern University Feinberg School of Medicine, Chicago, IL, U.S.A
| | - F J D Smith
- Pachyonychia Congenita Project, School of Life Sciences, University of Dundee, Dundee, U.K
| | - E Sprecher
- Department of Dermatology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.,Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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41
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Bharat TAM, Hoffmann PC, Kukulski W. Correlative Microscopy of Vitreous Sections Provides Insights into BAR-Domain Organization In Situ. Structure 2018; 26:879-886.e3. [PMID: 29681471 PMCID: PMC5992340 DOI: 10.1016/j.str.2018.03.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 02/22/2018] [Accepted: 03/22/2018] [Indexed: 12/15/2022]
Abstract
Electron microscopy imaging of macromolecular complexes in their native cellular context is limited by the inherent difficulty to acquire high-resolution tomographic data from thick cells and to specifically identify elusive structures within crowded cellular environments. Here, we combined cryo-fluorescence microscopy with electron cryo-tomography of vitreous sections into a coherent correlative microscopy workflow, ideal for detection and structural analysis of elusive protein assemblies in situ. We used this workflow to address an open question on BAR-domain coating of yeast plasma membrane compartments known as eisosomes. BAR domains can sense or induce membrane curvature, and form scaffold-like membrane coats in vitro. Our results demonstrate that in cells, the BAR protein Pil1 localizes to eisosomes of varying membrane curvature. Sub-tomogram analysis revealed a dense protein coat on curved eisosomes, which was not present on shallow eisosomes, indicating that while BAR domains can assemble at shallow membranes in vivo, scaffold formation is tightly coupled to curvature generation. Cryo-fluorescence microscopy eases electron cryo-tomography of vitreous sections Elusive protein assemblies are localized in situ by correlative microscopy Yeast BAR-domain protein Pil1 binds to plasma membrane with varying curvature Scaffold-like coats are only seen when Pil1 is bound to high curvature membranes
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Affiliation(s)
- Tanmay A M Bharat
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK; Central Oxford Structural and Molecular Imaging Centre, South Parks Road, Oxford OX1 3RE, UK; Structural Studies Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Patrick C Hoffmann
- Cell Biology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Wanda Kukulski
- Cell Biology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
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42
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Dunstone MA, de Marco A. Cryo-electron tomography: an ideal method to study membrane-associated proteins. Philos Trans R Soc Lond B Biol Sci 2018. [PMID: 28630150 DOI: 10.1098/rstb.2016.0210] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Cryo-electron tomography (cryo-ET) is a three-dimensional imaging technique that makes it possible to analyse the structure of complex and dynamic biological assemblies in their native conditions. The latest technological and image processing developments demonstrate that it is possible to obtain structural information at nanometre resolution. The sample preparation required for the cryo-ET technique does not require the isolation of a protein and other macromolecular complexes from its native environment. Therefore, cryo-ET is emerging as an important tool to study the structure of membrane-associated proteins including pores.This article is part of the themed issue 'Membrane pores: from structure and assembly, to medicine and technology'.
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Affiliation(s)
- Michelle A Dunstone
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia.,ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia.,Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia
| | - Alex de Marco
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia .,ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia
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Bartle EI, Urner TM, Raju SS, Mattheyses AL. Desmoglein 3 Order and Dynamics in Desmosomes Determined by Fluorescence Polarization Microscopy. Biophys J 2018; 113:2519-2529. [PMID: 29212005 DOI: 10.1016/j.bpj.2017.09.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 09/18/2017] [Accepted: 09/21/2017] [Indexed: 11/24/2022] Open
Abstract
Desmosomes are macromolecular cell-cell junctions that provide adhesive strength in epithelial tissue. Desmosome function is inseparably linked to structure, and it is hypothesized that the arrangement, or order, of desmosomal cadherins in the intercellular space is critical for adhesive strength. However, due to desmosome size, molecular complexity, and dynamics, the role that order plays in adhesion is challenging to study. Herein, we present an excitation resolved fluorescence polarization microscopy approach to measure the spatiotemporal dynamics of order and disorder of the desmosomal cadherin desmoglein 3 (Dsg3) in living cells. Simulations were used to establish order factor as a robust metric for quantifying the spatiotemporal dynamics of order and disorder. Order factor measurements in keratinocytes showed the Dsg3 extracellular domain is ordered at the individual desmosome, single cell, and cell population levels compared to a series of disordered controls. Desmosomal adhesion is Ca2+ dependent, and reduction of extracellular Ca2+ leads to a loss of adhesion measured by dispase fragmentation assay (λ = 15.1 min). Live cell imaging revealed Dsg3 order decreased more rapidly (λ = 5.5 min), indicating that cadherin order is not required for adhesion. Our results suggest that rapid disordering of cadherins can communicate a change in extracellular Ca2+ concentration to the cell, leading to a downstream loss of adhesion. Fluorescence polarization is an effective bridge between protein structure and complex dynamics and the approach presented here is broadly applicable to studying order in macromolecular structures.
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Affiliation(s)
- Emily I Bartle
- Department of Cell Biology, Emory University, Atlanta, Georgia
| | - Tara M Urner
- Department of Cell Biology, Emory University, Atlanta, Georgia
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Dieding M, Debus JD, Kerkhoff R, Gaertner-Rommel A, Walhorn V, Milting H, Anselmetti D. Arrhythmogenic cardiomyopathy related DSG2 mutations affect desmosomal cadherin binding kinetics. Sci Rep 2017; 7:13791. [PMID: 29062102 PMCID: PMC5653825 DOI: 10.1038/s41598-017-13737-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 09/26/2017] [Indexed: 01/03/2023] Open
Abstract
Cadherins are calcium dependent adhesion proteins that establish the intercellular mechanical contact by bridging the gap to adjacent cells. Desmoglein-2 (Dsg2) is a specific cadherin of the cell-cell contact in cardiac desmosomes. Mutations in the DSG2-gene are regarded to cause arrhythmogenic (right ventricular) cardiomyopathy (ARVC) which is a rare but severe heart muscle disease. The molecular pathomechanisms of the vast majority of DSG2 mutations, however, are unknown. Here, we investigated the homophilic binding of wildtype Dsg2 and two mutations which are associated with ARVC. Using single molecule force spectroscopy and applying Jarzynski’s equality we determined the kinetics and thermodynamics of Dsg2 homophilic binding. Notably, the free energy landscape of Dsg2 dimerization exposes a high activation barrier which is in line with the proposed strand-swapping binding motif. Although the binding motif is not directly affected by the mutations the binding kinetics differ significantly from the wildtype. Furthermore, we applied a dispase based cell dissociation assay using HT1080 cell lines over expressing Dsg2 wildtype and mutants, respectively. Our molecular and cellular results consistently demonstrate that Dsg2 mutations can heavily affect homophilic Dsg2 interactions. Furthermore, the full thermodynamic and kinetic description of Dsg2 dimerization provides a consistent model of the so far discussed homophilic cadherin binding.
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Affiliation(s)
- Mareike Dieding
- Experimental Biophysics and Applied Nanoscience, University of Bielefeld, Bielefeld, Germany
| | - Jana Davina Debus
- Erich & Hanna Klessmann Institute for Cardiovascular Research and Development, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Bad Oeynhausen, Germany
| | - Raimund Kerkhoff
- Experimental Biophysics and Applied Nanoscience, University of Bielefeld, Bielefeld, Germany
| | - Anna Gaertner-Rommel
- Erich & Hanna Klessmann Institute for Cardiovascular Research and Development, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Bad Oeynhausen, Germany
| | - Volker Walhorn
- Experimental Biophysics and Applied Nanoscience, University of Bielefeld, Bielefeld, Germany.
| | - Hendrik Milting
- Erich & Hanna Klessmann Institute for Cardiovascular Research and Development, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Bad Oeynhausen, Germany
| | - Dario Anselmetti
- Experimental Biophysics and Applied Nanoscience, University of Bielefeld, Bielefeld, Germany
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45
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Cipolla GA, Park JK, Lavker RM, Petzl-Erler ML. Crosstalk between Signaling Pathways in Pemphigus: A Role for Endoplasmic Reticulum Stress in p38 Mitogen-Activated Protein Kinase Activation? Front Immunol 2017; 8:1022. [PMID: 28928733 PMCID: PMC5591886 DOI: 10.3389/fimmu.2017.01022] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Accepted: 08/08/2017] [Indexed: 12/18/2022] Open
Abstract
Pemphigus consists of a group of chronic blistering skin diseases mediated by autoantibodies (autoAbs). The dogma that pemphigus is caused by keratinocyte dissociation (acantholysis) as a distinctive and direct consequence of the presence of autoAb targeting two main proteins of the desmosome—desmoglein (DSG) 1 and/or DSG3—has been put to the test. Several outside-in signaling events elicited by pemphigus autoAb in keratinocytes have been described, among which stands out p38 mitogen-activated protein kinase (p38 MAPK) engagement and its apoptotic effect on keratinocytes. The role of apoptosis in the disease is, however, debatable, to an extent that it may not be a determinant event for the occurrence of acantholysis. Also, it has been verified that compromised DSG trans-interaction does not lead to keratinocyte dissociation when p38 MAPK is inhibited. These examples of conflicting results have been followed by recent work revealing an important role for endoplasmic reticulum (ER) stress in pemphigus’ pathogenesis. ER stress is known to activate the p38 MAPK pathway, and vice versa. However, this relationship has not yet been studied in the context of activated signaling pathways in pemphigus. Therefore, by reviewing and hypothetically connecting the role(s) of ER stress and p38 MAPK pathway in pemphigus, we highlight the importance of elucidating the crosstalk between all activated signaling pathways, which may in turn contribute for a better understanding of the role of apoptosis in the disease and a better management of this life-threatening condition.
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Affiliation(s)
- Gabriel A Cipolla
- Department of Genetics, Federal University of Paraná, Curitiba, Brazil.,CAPES Foundation, Ministry of Education of Brazil, Brasília, Brazil
| | - Jong Kook Park
- Department of Dermatology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States.,Department of Biomedical Science and Research, Institute for Bioscience and Biotechnology, Hallym University, Chuncheon, South Korea
| | - Robert M Lavker
- Department of Dermatology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
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46
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Wagner J, Schaffer M, Fernández-Busnadiego R. Cryo-electron tomography-the cell biology that came in from the cold. FEBS Lett 2017; 591:2520-2533. [PMID: 28726246 DOI: 10.1002/1873-3468.12757] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 06/26/2017] [Accepted: 07/14/2017] [Indexed: 12/27/2022]
Abstract
Cryo-electron tomography (cryo-ET) provides high-resolution 3D views into cells pristinely preserved by vitrification. Recent technical advances such as direct electron detectors, the Volta phase plate and cryo-focused ion beam milling have dramatically pushed image quality and expanded the range of cryo-ET applications. Cryo-ET not only allows mapping the positions and interactions of macromolecules within their intact cellular context, but can also reveal their in situ structure at increasing resolution. Here, we review how recent work using cutting-edge cryo-ET technologies is starting to provide fresh views into different aspects of cellular biology at an unprecedented level of detail. We anticipate that these developments will soon make cryo-ET a fundamental technique in cell biology.
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47
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Three-Dimensional Imaging of Biological Tissue by Cryo X-Ray Ptychography. Sci Rep 2017; 7:6291. [PMID: 28740127 PMCID: PMC5524705 DOI: 10.1038/s41598-017-05587-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 05/31/2017] [Indexed: 12/16/2022] Open
Abstract
High-throughput three-dimensional cryogenic imaging of thick biological specimens is valuable for identifying biologically- or pathologically-relevant features of interest, especially for subsequent correlative studies. Unfortunately, high-resolution imaging techniques at cryogenic conditions often require sample reduction through sequential physical milling or sectioning for sufficient penetration to generate each image of the 3-D stack. This study represents the first demonstration of using ptychographic hard X-ray tomography at cryogenic temperatures for imaging thick biological tissue in a chemically-fixed, frozen-hydrated state without heavy metal staining and organic solvents. Applied to mammalian brain, this label-free cryogenic imaging method allows visualization of myelinated axons and sub-cellular features such as age-related pigmented cellular inclusions at a spatial resolution of ~100 nanometers and thicknesses approaching 100 microns. Because our approach does not require dehydration, staining or reduction of the sample, we introduce the possibility for subsequent analysis of the same tissue using orthogonal approaches that are expected to yield direct complementary insight to the biological features of interest.
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48
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Scheffer MP, Gonzalez-Gonzalez L, Seybert A, Ratera M, Kunz M, Valpuesta JM, Fita I, Querol E, Piñol J, Martín-Benito J, Frangakis AS. Structural characterization of the NAP; the major adhesion complex of the human pathogen Mycoplasma genitalium. Mol Microbiol 2017; 105:869-879. [PMID: 28671286 DOI: 10.1111/mmi.13743] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/29/2017] [Indexed: 01/09/2023]
Abstract
Mycoplasma genitalium, the causative agent of non-gonococcal urethritis and pelvic inflammatory disease in humans, is a small eubacterium that lacks a peptidoglycan cell wall. On the surface of its plasma membrane is the major surface adhesion complex, known as NAP that is essential for adhesion and gliding motility of the organism. Here, we have performed cryo-electron tomography of intact cells and detergent permeabilized M. genitalium cell aggregates, providing sub-tomogram averages of free and cell-attached NAPs respectively, revealing a tetrameric complex with two-fold rotational (C2) symmetry. Each NAP has two pairs of globular lobes (named α and β lobes), arranged as a dimer of heterodimers with each lobe connected by a stalk to the cell membrane. The β lobes are larger than the α lobes by 20%. Classification of NAPs showed that the complex can tilt with respect to the cell membrane. A protein complex containing exclusively the proteins P140 and P110, was purified from M. genitalium and was structurally characterized by negative-stain single particle EM reconstruction. The close structural similarity found between intact NAPs and the isolated P140/P110 complexes, shows that dimers of P140/P110 heterodimers are the only components of the extracellular region of intact NAPs in M. genitalium.
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Affiliation(s)
- Margot P Scheffer
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Max-von-Laue Str. 15, Frankfurt 60438, Germany
| | - Luis Gonzalez-Gonzalez
- Departament de Bioquímica i Biologia Molecular and Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Spain
| | - Anja Seybert
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Max-von-Laue Str. 15, Frankfurt 60438, Germany
| | - Mercè Ratera
- Parc Científic de Barcelona, Instituto de Biología Molecular de Barcelona del (IBMB-CSIC), Baldiri i Reixac 10, Barcelona 08028, Spain
| | - Michael Kunz
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Max-von-Laue Str. 15, Frankfurt 60438, Germany
| | - José M Valpuesta
- Department for Macromolecular Structures, Centro Nacional de Biotecnologıa (CNB-CSIC), Madrid 28049, Spain
| | - Ignacio Fita
- Parc Científic de Barcelona, Instituto de Biología Molecular de Barcelona del (IBMB-CSIC), Baldiri i Reixac 10, Barcelona 08028, Spain
| | - Enrique Querol
- Departament de Bioquímica i Biologia Molecular and Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Spain
| | - Jaume Piñol
- Departament de Bioquímica i Biologia Molecular and Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Spain
| | - Jaime Martín-Benito
- Department for Macromolecular Structures, Centro Nacional de Biotecnologıa (CNB-CSIC), Madrid 28049, Spain
| | - Achilleas S Frangakis
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Max-von-Laue Str. 15, Frankfurt 60438, Germany
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49
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Irudayanathan FJ, Wang N, Wang X, Nangia S. Architecture of the paracellular channels formed by claudins of the blood–brain barrier tight junctions. Ann N Y Acad Sci 2017; 1405:131-146. [DOI: 10.1111/nyas.13378] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 04/12/2017] [Accepted: 04/14/2017] [Indexed: 01/31/2023]
Affiliation(s)
| | - Nan Wang
- Department of Biomedical and Chemical Engineering Syracuse University Syracuse New York
| | - Xiaoyi Wang
- Department of Biomedical and Chemical Engineering Syracuse University Syracuse New York
| | - Shikha Nangia
- Department of Biomedical and Chemical Engineering Syracuse University Syracuse New York
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50
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Rickgauer JP, Grigorieff N, Denk W. Single-protein detection in crowded molecular environments in cryo-EM images. eLife 2017; 6. [PMID: 28467302 PMCID: PMC5453696 DOI: 10.7554/elife.25648] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 05/02/2017] [Indexed: 12/22/2022] Open
Abstract
We present an approach to study macromolecular assemblies by detecting component proteins' characteristic high-resolution projection patterns, calculated from their known 3D structures, in single electron cryo-micrographs. Our method detects single apoferritin molecules in vitreous ice with high specificity and determines their orientation and location precisely. Simulations show that high spatial-frequency information and-in the presence of protein background-a whitening filter are essential for optimal detection, in particular for images taken far from focus. Experimentally, we could detect small viral RNA polymerase molecules, distributed randomly among binding locations, inside rotavirus particles. Based on the currently attainable image quality, we estimate a threshold for detection that is 150 kDa in ice and 300 kDa in 100 nm thick samples of dense biological material.
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Affiliation(s)
| | | | - Winfried Denk
- Howard Hughes Medical Institute, Ashburn, United States.,Department of Electrons - Photons - Neurons, Max Planck Institute of Neurobiology, Martinsried, Germany
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