1
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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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Bharathan NK, Mattheyses AL, Kowalczyk AP. The desmosome comes into focus. J Cell Biol 2024; 223:e202404120. [PMID: 39120608 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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3
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Luo Q, Li X, Xie K. Plakophilin 1 in carcinogenesis. Mol Carcinog 2024. [PMID: 38888207 DOI: 10.1002/mc.23779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 05/11/2024] [Accepted: 06/06/2024] [Indexed: 06/20/2024]
Abstract
Plakophilin 1 (PKP1) belongs to the desmosome family as an anchoring junction protein in cellular junctions. It localizes at the interface of the cell membrane and cytoplasm. Although PKP1 is a non-transmembrane protein, it may become associated with the cell membrane via transmembrane proteins such as desmocollins and desmogleins. Homozygous deletion of PKP1 results in ectodermal dysplasia-skin fragility syndrome (EDSF) and complete knockout of PKP1 in mice produces comparable symptoms to EDSF in humans, although mice do not survive more than 24 h. PKP1 is not limited to expression in desmosomal structures, but is rather widely expressed in cytoplasm and nucleus, where it assumes important cellular functions. This review will summarize distinct roles of PKP1 in the cell membrane, cytoplasm, and nucleus with an overview of relevant studies on its function in diverse types of cancer.
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Affiliation(s)
- Qiang Luo
- Center for Pancreatic Cancer Research, The South China University of Technology School of Medicine, Guangzhou, Guangdong, China
| | - Xiaojia Li
- Center for Pancreatic Cancer Research, The South China University of Technology School of Medicine, Guangzhou, Guangdong, China
| | - Keping Xie
- Center for Pancreatic Cancer Research, The South China University of Technology School of Medicine, Guangzhou, Guangdong, China
- The Second Affiliated Hospital and Guangzhou First People's Hospital, South China University of Technology School of Medicine, Guangzhou, Guangdong, China
- The South China University of Technology Comprehensive Cancer Center, Guangzhou, Guangdong, China
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4
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Zimmer SE, Giang W, Levental I, Kowalczyk AP. The transmembrane domain of the desmosomal cadherin desmoglein-1 governs lipid raft association to promote desmosome adhesive strength. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.24.590936. [PMID: 38712246 PMCID: PMC11071526 DOI: 10.1101/2024.04.24.590936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Cholesterol- and sphingolipid-enriched domains called lipid rafts are hypothesized to selectively coordinate protein complex assembly within the plasma membrane to regulate cellular functions. Desmosomes are mechanically resilient adhesive junctions that associate with lipid raft membrane domains, yet the mechanisms directing raft association of the desmosomal proteins, particularly the transmembrane desmosomal cadherins, are poorly understood. We identified the desmoglein-1 (DSG1) transmembrane domain (TMD) as a key determinant of desmoglein lipid raft association and designed a panel of DSG1 TMD variants to assess the contribution of TMD physicochemical properties (length, bulkiness, and palmitoylation) to DSG1 lipid raft association. Sucrose gradient fractionations revealed that TMD length and bulkiness, but not palmitoylation, govern DSG1 lipid raft association. Further, DSG1 raft association determines plakoglobin recruitment to raft domains. Super-resolution imaging and functional assays uncovered a strong relationship between the efficiency of DSG1 TMD lipid raft association and the formation of morphologically and functionally robust desmosomes. Lipid raft association regulated both desmosome assembly dynamics and DSG1 cell surface stability, indicating that DSG1 lipid raft association is required for both desmosome formation and maintenance. These studies identify the biophysical properties of desmoglein transmembrane domains as key determinants of lipid raft association and desmosome adhesive function.
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5
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Verkerk AJMH, Andrei D, Vermeer MCSC, Kramer D, Schouten M, Arp P, Verlouw JAM, Pas HH, Meijer HJ, van der Molen M, Oberdorf-Maass S, Nijenhuis M, Romero-Herrera PH, Hoes MF, Bremer J, Slotman JA, van den Akker PC, Diercks GFH, Giepmans BNG, Stoop H, Saris JJ, van den Ouweland AMW, Willemsen R, Hublin JJ, Dean MC, Hoogeboom AJM, Silljé HHW, Uitterlinden AG, van der Meer P, Bolling MC. Disruption of TUFT1, a Desmosome-Associated Protein, Causes Skin Fragility, Woolly Hair, and Palmoplantar Keratoderma. J Invest Dermatol 2024; 144:284-295.e16. [PMID: 37716648 DOI: 10.1016/j.jid.2023.02.044] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 06/24/2023] [Indexed: 09/18/2023]
Abstract
Desmosomes are dynamic complex protein structures involved in cellular adhesion. Disruption of these structures by loss-of-function variants in desmosomal genes leads to a variety of skin- and heart-related phenotypes. In this study, we report TUFT1 as a desmosome-associated protein, implicated in epidermal integrity. In two siblings with mild skin fragility, woolly hair, and mild palmoplantar keratoderma but without a cardiac phenotype, we identified a homozygous splice-site variant in the TUFT1 gene, leading to aberrant mRNA splicing and loss of TUFT1 protein. Patients' skin and keratinocytes showed acantholysis, perinuclear retraction of intermediate filaments, and reduced mechanical stress resistance. Immunolabeling and transfection studies showed that TUFT1 is positioned within the desmosome and that its location is dependent on the presence of the desmoplakin carboxy-terminal tail. A Tuft1-knockout mouse model mimicked the patients' phenotypes. Altogether, this study reveals TUFT1 as a desmosome-associated protein, whose absence causes skin fragility, woolly hair, and palmoplantar keratoderma.
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Affiliation(s)
- Annemieke J M H Verkerk
- Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
| | - Daniela Andrei
- Department of Dermatology, University of Groningen, University Medical Centre Groningen, Center of Expertise for Blistering Diseases, Groningen, The Netherlands
| | - Mathilde C S C Vermeer
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Duco Kramer
- Department of Dermatology, University of Groningen, University Medical Centre Groningen, Center of Expertise for Blistering Diseases, Groningen, The Netherlands
| | - Marloes Schouten
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Pascal Arp
- Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Joost A M Verlouw
- Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Hendri H Pas
- Department of Dermatology, University of Groningen, University Medical Centre Groningen, Center of Expertise for Blistering Diseases, Groningen, The Netherlands
| | - Hillegonda J Meijer
- Department of Dermatology, University of Groningen, University Medical Centre Groningen, Center of Expertise for Blistering Diseases, Groningen, The Netherlands
| | - Marije van der Molen
- Department of Dermatology, University of Groningen, University Medical Centre Groningen, Center of Expertise for Blistering Diseases, Groningen, The Netherlands
| | - Silke Oberdorf-Maass
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Miranda Nijenhuis
- Department of Dermatology, University of Groningen, University Medical Centre Groningen, Center of Expertise for Blistering Diseases, Groningen, The Netherlands
| | - Pedro H Romero-Herrera
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Martijn F Hoes
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Jeroen Bremer
- Department of Dermatology, University of Groningen, University Medical Centre Groningen, Center of Expertise for Blistering Diseases, Groningen, The Netherlands
| | - Johan A Slotman
- Optical Imaging Centre, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Peter C van den Akker
- Department of Genetics, University of Groningen, University Medical Centre Groningen, Center of Expertise for Blistering Diseases, Groningen, The Netherlands
| | - Gilles F H Diercks
- Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Ben N G Giepmans
- Department of Biomedical Sciences of Cells & Systems, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands
| | - Hans Stoop
- Department of Pathology, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Jasper J Saris
- Department of Clinical Genetics, Erasmus University Medical Center, Rotterdam, The Netherlands
| | | | - Rob Willemsen
- Department of Clinical Genetics, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Jean-Jacques Hublin
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany; Chaire de Paléoanthropologie, CIRB (UMR 7241 - U1050), Collège de France, Paris, France
| | - M Christopher Dean
- Centre for Human Origins Research, Natural History Museum, London, United Kingdom; Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - A Jeannette M Hoogeboom
- Department of Clinical Genetics, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Herman H W Silljé
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - André G Uitterlinden
- Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Peter van der Meer
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Maria C Bolling
- Department of Dermatology, University of Groningen, University Medical Centre Groningen, Center of Expertise for Blistering Diseases, Groningen, The Netherlands.
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6
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Bharathan NK, Giang W, Hoffman CL, Aaron JS, Khuon S, Chew TL, Preibisch S, Trautman ET, Heinrich L, Bogovic J, Bennett D, Ackerman D, Park W, Petruncio A, Weigel AV, Saalfeld S, Wayne Vogl A, Stahley SN, Kowalczyk AP. Architecture and dynamics of a desmosome-endoplasmic reticulum complex. Nat Cell Biol 2023; 25:823-835. [PMID: 37291267 PMCID: PMC10960982 DOI: 10.1038/s41556-023-01154-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 04/24/2023] [Indexed: 06/10/2023]
Abstract
The endoplasmic reticulum (ER) forms a dynamic network that contacts other cellular membranes to regulate stress responses, calcium signalling and lipid transfer. Here, using high-resolution volume electron microscopy, we find that the ER forms a previously unknown association with keratin intermediate filaments and desmosomal cell-cell junctions. Peripheral ER assembles into mirror image-like arrangements at desmosomes and exhibits nanometre proximity to keratin filaments and the desmosome cytoplasmic plaque. ER tubules exhibit stable associations with desmosomes, and perturbation of desmosomes or keratin filaments alters ER organization, mobility and expression of ER stress transcripts. These findings indicate that desmosomes and the keratin cytoskeleton regulate the distribution, function and dynamics of the ER network. Overall, this study reveals a previously unknown subcellular architecture defined by the structural integration of ER tubules with an epithelial intercellular junction.
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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
| | - William Giang
- Departments of Dermatology and Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Coryn L Hoffman
- Departments of Dermatology and Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Jesse S Aaron
- Advanced Imaging Center, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Satya Khuon
- Advanced Imaging Center, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Teng-Leong Chew
- Advanced Imaging Center, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Stephan Preibisch
- Advanced Imaging Center, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Eric T Trautman
- Advanced Imaging Center, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Larissa Heinrich
- Advanced Imaging Center, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - John Bogovic
- Advanced Imaging Center, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Davis Bennett
- Advanced Imaging Center, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - David Ackerman
- Advanced Imaging Center, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Woohyun Park
- Advanced Imaging Center, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Alyson Petruncio
- Advanced Imaging Center, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Aubrey V Weigel
- Advanced Imaging Center, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Stephan Saalfeld
- Advanced Imaging Center, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - A Wayne Vogl
- Life Sciences Institute and the Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Sara N Stahley
- Departments of Dermatology and Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, PA, 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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7
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Vanslembrouck B, Chen JH, Larabell C, van Hengel J. Microscopic Visualization of Cell-Cell Adhesion Complexes at Micro and Nanoscale. Front Cell Dev Biol 2022; 10:819534. [PMID: 35517500 PMCID: PMC9065677 DOI: 10.3389/fcell.2022.819534] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Accepted: 03/21/2022] [Indexed: 12/25/2022] Open
Abstract
Considerable progress has been made in our knowledge of the morphological and functional varieties of anchoring junctions. Cell-cell adhesion contacts consist of discrete junctional structures responsible for the mechanical coupling of cytoskeletons and allow the transmission of mechanical signals across the cell collective. The three main adhesion complexes are adherens junctions, tight junctions, and desmosomes. Microscopy has played a fundamental role in understanding these adhesion complexes on different levels in both physiological and pathological conditions. In this review, we discuss the main light and electron microscopy techniques used to unravel the structure and composition of the three cell-cell contacts in epithelial and endothelial cells. It functions as a guide to pick the appropriate imaging technique(s) for the adhesion complexes of interest. We also point out the latest techniques that have emerged. At the end, we discuss the problems investigators encounter during their cell-cell adhesion research using microscopic techniques.
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Affiliation(s)
- Bieke Vanslembrouck
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
- Department of Anatomy, University of San Francisco, San Francisco, CA, United States
- *Correspondence: Bieke Vanslembrouck, ; Jolanda van Hengel,
| | - Jian-hua Chen
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
- Department of Anatomy, University of San Francisco, San Francisco, CA, United States
| | - Carolyn Larabell
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
- Department of Anatomy, University of San Francisco, San Francisco, CA, United States
| | - Jolanda van Hengel
- Medical Cell Biology Research Group, Department of Human Structure and Repair, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
- *Correspondence: Bieke Vanslembrouck, ; Jolanda van Hengel,
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8
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Büchau F, Vielmuth F, Waschke J, Magin TM. Bidirectional regulation of desmosome hyperadhesion by keratin isotypes and desmosomal components. Cell Mol Life Sci 2022; 79:223. [PMID: 35380280 PMCID: PMC8983532 DOI: 10.1007/s00018-022-04244-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 03/04/2022] [Accepted: 03/10/2022] [Indexed: 11/30/2022]
Abstract
Desmosomes are intercellular junctions which mediate cohesion and communication in tissues exposed to mechanical strain by tethering the intermediate filament cytoskeleton to the plasma membrane. While mature desmosomes are characterized by a hyperadhesive, Ca2+-independent state, they transiently loose this state during wound healing, pathogenesis and tissue regeneration. The mechanisms controlling the hyperadhesive state remain incompletely understood. Here, we show that upon Ca2+-induced keratinocyte differentiation, expression of keratin 17 (K17) prevents the formation of stable and hyperadhesive desmosomes, accompanied by a significant reduction of desmoplakin (DP), plakophilin-1 (PKP1), desmoglein-1 (Dsg1) and -3 (Dsg3) at intercellular cell borders. Atomic force microscopy revealed that both increased binding strength of desmoglein-3 molecules and amount of desmoglein-3 oligomers, known hallmarks of hyperadhesion, were reduced in K17- compared to K14-expressing cells. Importantly, overexpression of Dsg3 or DPII enhanced their localization at intercellular cell borders and increased the formation of Dsg3 oligomers, resulting in stable, hyperadhesive desmosomes despite the presence of K17. Notably, PKP1 was enriched in these desmosomes. Quantitative image analysis revealed that DPII overexpression contributed to desmosome hyperadhesion by increasing the abundance of K5/K17-positive keratin filaments in the proximity of desmosomes enriched in desmoglein-3. Thus, our data show that hyperadhesion can result from recruitment of keratin isotypes K5/K17 to desmosomes or from enhanced expression of DP and Dsg3 irrespective of keratin composition. The notion that hyperadhesive desmosomes failed to form in the absence of keratins underscores the essential role of keratins and suggest bidirectional control mechanisms at several levels.
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Affiliation(s)
- Fanny Büchau
- Institute of Biology, Division of Cell and Developmental Biology, University of Leipzig, Philipp-Rosenthal-Straße 55, 04103, Leipzig, Germany.
| | - Franziska Vielmuth
- Chair of Vegetative Anatomy, Institute of Anatomy, Faculty of Medicine, LMU Munich, Munich, Germany
| | - Jens Waschke
- Chair of Vegetative Anatomy, Institute of Anatomy, Faculty of Medicine, LMU Munich, Munich, Germany
| | - Thomas M Magin
- Institute of Biology, Division of Cell and Developmental Biology, University of Leipzig, Philipp-Rosenthal-Straße 55, 04103, Leipzig, Germany
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9
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Beggs RR, Rao TC, Dean WF, Kowalczyk AP, Mattheyses AL. Desmosomes undergo dynamic architectural changes during assembly and maturation. Tissue Barriers 2022; 10:2017225. [PMID: 34983311 PMCID: PMC9621066 DOI: 10.1080/21688370.2021.2017225] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Desmosomes are macromolecular cell-cell junctions critical for maintaining adhesion and resisting mechanical stress in epithelial tissue. Desmosome assembly and the relationship between maturity and molecular architecture are not well understood. To address this, we employed a calcium switch assay to synchronize assembly followed by quantification of desmosome nanoscale organization using direct Stochastic Optical Reconstruction Microscopy (dSTORM). We found that the organization of the desmoplakin rod/C-terminal junction changed over the course of maturation, as indicated by a decrease in the plaque-to-plaque distance, while the plaque length increased. In contrast, the desmoplakin N-terminal domain and plakoglobin organization (plaque-to-plaque distance) were constant throughout maturation. This structural rearrangement of desmoplakin was concurrent with desmosome maturation measured by E-cadherin exclusion and increased adhesive strength. Using two-color dSTORM, we showed that while the number of individual E-cadherin containing junctions went down with the increasing time in high Ca2+, they maintained a wider desmoplakin rod/C-terminal plaque-to-plaque distance. This indicates that the maturation state of individual desmosomes can be identified by their architectural organization. We confirmed these architectural changes in another model of desmosome assembly, cell migration. Desmosomes in migrating cells, closest to the scratch where they are assembling, were shorter, E-cadherin enriched, and had wider desmoplakin rod/C-terminal plaque-to-plaque distances compared to desmosomes away from the wound edge. Key results were demonstrated in three cell lines representing simple, transitional, and stratified epithelia. Together, these data suggest that there is a set of architectural programs for desmosome maturation, and we hypothesize that desmoplakin architecture may be a contributing mechanism to regulating adhesive strength.
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Affiliation(s)
- Reena R Beggs
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Tejeshwar C Rao
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - William F Dean
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Andrew P Kowalczyk
- Departments of Dermatology and Cellular and Molecular Physiology, Pennsylvania State College of Medicine, Hershey, PA, USA
| | - Alexa L Mattheyses
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
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10
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Stahley SN, Basta LP, Sharan R, Devenport D. Celsr1 adhesive interactions mediate the asymmetric organization of planar polarity complexes. eLife 2021; 10:e62097. [PMID: 33529151 PMCID: PMC7857726 DOI: 10.7554/elife.62097] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 01/23/2021] [Indexed: 12/31/2022] Open
Abstract
To orchestrate collective polarization across tissues, planar cell polarity (PCP) proteins localize asymmetrically to cell junctions, a conserved feature of PCP that requires the atypical cadherin Celsr1. We report that mouse Celsr1 engages in both trans- and cis-interactions, and organizes into dense and highly stable punctate assemblies. We provide evidence suggesting that PCP-mutant variant of Celsr1, Celsr1Crsh, selectively impairs lateral cis-interactions. Although Celsr1Crsh mediates cell adhesion in trans, it displays increased mobility, diminishes junctional enrichment, and fails to engage in homophilic adhesion with the wild-type protein, phenotypes that can be rescued by ectopic cis-dimerization. Using biochemical and super-resolution microscopy approaches, we show that although Celsr1Crsh physically interacts with PCP proteins Frizzled6 and Vangl2, it fails to organize these proteins into asymmetric junctional complexes. Our results suggest mammalian Celsr1 functions not only as a trans-adhesive homodimeric bridge, but also as an organizer of intercellular Frizzled6 and Vangl2 asymmetry through lateral, cis-interactions.
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Affiliation(s)
- Sara N Stahley
- Department of Molecular Biology, Princeton UniversityPrincetonUnited States
| | - Lena P Basta
- Department of Molecular Biology, Princeton UniversityPrincetonUnited States
| | - Rishabh Sharan
- Department of Molecular Biology, Princeton UniversityPrincetonUnited States
| | - Danelle Devenport
- Department of Molecular Biology, Princeton UniversityPrincetonUnited States
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11
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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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12
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Nowak MB, Greer-Short A, Wan X, Wu X, Deschênes I, Weinberg SH, Poelzing S. Intercellular Sodium Regulates Repolarization in Cardiac Tissue with Sodium Channel Gain of Function. Biophys J 2020; 118:2829-2843. [PMID: 32402243 DOI: 10.1016/j.bpj.2020.04.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 03/26/2020] [Accepted: 04/10/2020] [Indexed: 11/30/2022] Open
Abstract
In cardiac myocytes, action potentials are initiated by an influx of sodium (Na+) ions via voltage-gated Na+ channels. Na+ channel gain of function (GOF), arising in both inherited conditions associated with mutation in the gene encoding the Na+ channel and acquired conditions associated with heart failure, ischemia, and atrial fibrillation, enhance Na+ influx, generating a late Na+ current that prolongs action potential duration (APD) and triggering proarrhythmic early afterdepolarizations (EADs). Recent studies have shown that Na+ channels are highly clustered at the myocyte intercalated disk, facilitating formation of Na+ nanodomains in the intercellular cleft between cells. Simulations from our group have recently predicted that narrowing the width of the intercellular cleft can suppress APD prolongation and EADs in the presence of Na+ channel mutations because of increased intercellular cleft Na+ ion depletion. In this study, we investigate the effects of modulating multiple extracellular spaces, specifically the intercellular cleft and bulk interstitial space, in a novel computational model and experimentally via osmotic agents albumin, dextran 70, and mannitol. We perform optical mapping and transmission electron microscopy in a drug-induced (sea anemone toxin, ATXII) Na+ channel GOF isolated heart model and modulate extracellular spaces via osmotic agents. Single-cell patch-clamp experiments confirmed that the osmotic agents individually do not enhance late Na+ current. Both experiments and simulations are consistent with the conclusion that intercellular cleft narrowing or expansion regulates APD prolongation; in contrast, modulating the bulk interstitial space has negligible effects on repolarization. Thus, we predict that intercellular cleft Na+ nanodomain formation and collapse critically regulates cardiac repolarization in the setting of Na+ channel GOF.
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Affiliation(s)
- Madison B Nowak
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio; Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia
| | - Amara Greer-Short
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio; Translational Biology, Medicine, and Health Graduate Program, Virginia Polytechnic Institute and State University, Blacksburg, Virginia
| | - Xiaoping Wan
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio; Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio
| | - Xiaobo Wu
- Translational Biology, Medicine, and Health Graduate Program, Virginia Polytechnic Institute and State University, Blacksburg, Virginia; Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Polytechnic Institute and State University, Roanoke, Virginia
| | - Isabelle Deschênes
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio; Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio
| | - Seth H Weinberg
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio; Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia.
| | - Steven Poelzing
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Polytechnic Institute and State University, Roanoke, Virginia; Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia.
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13
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Badu-Nkansah KA, Lechler T. Proteomic analysis of desmosomes reveals novel components required for epidermal integrity. Mol Biol Cell 2020; 31:1140-1153. [PMID: 32238101 PMCID: PMC7353166 DOI: 10.1091/mbc.e19-09-0542] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Desmosomes are cell–cell adhesions necessary for the maintenance of tissue integrity in the skin and heart. While the core components of desmosomes have been identified, peripheral components that modulate canonical or noncanonical desmosome functions still remain largely unexplored. Here we used targeted proximity labeling approaches to further elaborate the desmosome proteome in epidermal keratinocytes. Quantitative mass spectrometry analysis identified all core desmosomal proteins while uncovering a diverse array of new constituents with broad molecular functions. By individually targeting the inner and outer dense plaques, we defined proteins enriched within these subcompartments. We validated a number of these novel desmosome-associated proteins and find that many are membrane proximal proteins that show a dependence on functional desmosomes for their cortical localization. We further explored the mechanism of localization and function of two novel desmosome-associated adaptor proteins enriched in the desmosome proteome, Crk and Crk-like (CrkL). These proteins interacted with Dsg1 and rely on Dsg1 and desmoplakin for robust cortical localization. Epidermal deletion of both Crk and CrkL resulted in perinatal lethality with defects in desmosome morphology and keratin organization, thus demonstrating the utility of this dataset in identifying novel proteins required for desmosome-dependent epidermal integrity.
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Affiliation(s)
- Kwabena A Badu-Nkansah
- Department of Dermatology and Department of Cell Biology, Duke University, Durham, NC 27710
| | - Terry Lechler
- Department of Dermatology and Department of Cell Biology, Duke University, Durham, NC 27710
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14
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Abstract
Desmosomes are cell-cell junctions responsible for mechanically integrating adjacent cells. Due to the small size of the junctions, their protein architecture cannot be elucidated using conventional fluorescence microscopy. Super-resolution microscopy techniques, including dSTORM, deliver higher-resolution images which can reveal the localization or arrangement of proteins within individual desmosomes. Herein we describe an imaging and analysis method to determine the nanoscale architecture of desmosomes using super-resolution dSTORM.
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Affiliation(s)
- Reena R Beggs
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - William F Dean
- 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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15
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Fuchs M, Foresti M, Radeva MY, Kugelmann D, Keil R, Hatzfeld M, Spindler V, Waschke J, Vielmuth F. Plakophilin 1 but not plakophilin 3 regulates desmoglein clustering. Cell Mol Life Sci 2019; 76:3465-3476. [PMID: 30949721 PMCID: PMC11105395 DOI: 10.1007/s00018-019-03083-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 02/15/2019] [Accepted: 03/25/2019] [Indexed: 12/25/2022]
Abstract
Plakophilins (Pkp) are desmosomal plaque proteins crucial for desmosomal adhesion and participate in the regulation of desmosomal turnover and signaling. However, direct evidence that Pkps regulate clustering and molecular binding properties of desmosomal cadherins is missing. Here, keratinocytes lacking either Pkp1 or 3 in comparison to wild type (wt) keratinocytes were characterized with regard to their desmoglein (Dsg) 1- and 3-binding properties and their capability to induce Dsg3 clustering. As revealed by atomic force microscopy (AFM), both Pkp-deficient keratinocyte cell lines showed reduced membrane availability and binding frequency of Dsg1 and 3 at cell borders. Extracellular crosslinking and AFM cluster mapping demonstrated that Pkp1 but not Pkp3 is required for Dsg3 clustering. Accordingly, Dsg3 overexpression reconstituted cluster formation in Pkp3- but not Pkp1-deficient keratinocytes as shown by AFM and STED experiments. Taken together, these data demonstrate that both Pkp1 and 3 regulate Dsg membrane availability, whereas Pkp1 but not Pkp3 is required for Dsg3 clustering.
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Affiliation(s)
- Michael Fuchs
- Faculty of Medicine, Institute of Anatomy, Ludwig-Maximilians-Universität Munich, Pettenkoferstr. 11, 80336, Munich, Germany
| | - Marco Foresti
- Faculty of Medicine, Institute of Anatomy, Ludwig-Maximilians-Universität Munich, Pettenkoferstr. 11, 80336, Munich, Germany
| | - Mariya Y Radeva
- Faculty of Medicine, Institute of Anatomy, Ludwig-Maximilians-Universität Munich, Pettenkoferstr. 11, 80336, Munich, Germany
| | - Daniela Kugelmann
- Faculty of Medicine, Institute of Anatomy, Ludwig-Maximilians-Universität Munich, Pettenkoferstr. 11, 80336, Munich, Germany
| | - Rene Keil
- Division of Pathobiochemistry, Institute of Molecular Medicine, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Mechthild Hatzfeld
- Division of Pathobiochemistry, Institute of Molecular Medicine, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Volker Spindler
- Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Jens Waschke
- Faculty of Medicine, Institute of Anatomy, Ludwig-Maximilians-Universität Munich, Pettenkoferstr. 11, 80336, Munich, Germany.
| | - Franziska Vielmuth
- Faculty of Medicine, Institute of Anatomy, Ludwig-Maximilians-Universität Munich, Pettenkoferstr. 11, 80336, Munich, Germany.
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16
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Abstract
The skin provides the primary protection for the body against external injuries and is essential in the maintenance of general homeostasis. During ageing, resident cells become senescent and the extracellular matrix, mainly in the dermis, is progressively damaged affecting the normal organization of the skin and its capacity for repair. In parallel, extrinsic factors such as ultraviolet irradiation, pollution, and intrinsic factors such as diabetes or vascular disease can further accelerate this phenomenon. Indeed, numerous mechanisms are involved in age-induced degradation of the skin and these also relate to non-healing or chronic wounds in the elderly. In particular, the generation of reactive oxygen species seems to play a major role in age-related skin modifications. Certainly, targeting both the hormonal status of the skin or its surface nutrition can slow down age-induced degradation of the skin and improve healing of skin damage in the elderly. Skin care regimens that prevent radiation and pollution damage, and reinforce the skin surface and its microbiota are among the different approaches able to minimize the effects of ageing on the skin.
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17
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Shafraz O, Rübsam M, Stahley SN, Caldara AL, Kowalczyk AP, Niessen CM, Sivasankar S. E-cadherin binds to desmoglein to facilitate desmosome assembly. eLife 2018; 7:37629. [PMID: 29999492 PMCID: PMC6066328 DOI: 10.7554/elife.37629] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 07/10/2018] [Indexed: 02/04/2023] Open
Abstract
Desmosomes are adhesive junctions composed of two desmosomal cadherins: desmocollin (Dsc) and desmoglein (Dsg). Previous studies demonstrate that E-cadherin (Ecad), an adhesive protein that interacts in both trans (between opposing cells) and cis (on the same cell surface) conformations, facilitates desmosome assembly via an unknown mechanism. Here we use structure-function analysis to resolve the mechanistic roles of Ecad in desmosome formation. Using AFM force measurements, we demonstrate that Ecad interacts with isoform 2 of Dsg via a conserved Leu-175 on the Ecad cis binding interface. Super-resolution imaging reveals that Ecad is enriched in nascent desmosomes, supporting a role for Ecad in early desmosome assembly. Finally, confocal imaging demonstrates that desmosome assembly is initiated at sites of Ecad mediated adhesion, and that Ecad-L175 is required for efficient Dsg2 and desmoplakin recruitment to intercellular contacts. We propose that Ecad trans interactions at nascent cell-cell contacts initiate the recruitment of Dsg through direct cis interactions with Ecad which facilitates desmosome assembly.
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Affiliation(s)
- Omer Shafraz
- Department of Physics and Astronomy, Iowa State University, Ames, United States
| | - Matthias Rübsam
- Department of Dermatology, Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases, Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Sara N Stahley
- Department of Cell Biology, Emory University School of Medicine, Atlanta, United States
| | - Amber L Caldara
- Department of Cell Biology, Emory University School of Medicine, Atlanta, United States
| | - Andrew P Kowalczyk
- Department of Cell Biology, Emory University School of Medicine, Atlanta, United States
| | - Carien M Niessen
- Department of Dermatology, Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases, Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Sanjeevi Sivasankar
- Department of Physics and Astronomy, Iowa State University, Ames, United States
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18
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Ishida-Yamamoto A, Igawa S, Kishibe M, Honma M. Clinical and molecular implications of structural changes to desmosomes and corneodesmosomes. J Dermatol 2018; 45:385-389. [DOI: 10.1111/1346-8138.14202] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Accepted: 11/28/2017] [Indexed: 10/18/2022]
Affiliation(s)
| | - Satomi Igawa
- Department of Dermatology; Asahikawa Medical University; Asahikawa Japan
| | - Mari Kishibe
- Department of Dermatology; Asahikawa Medical University; Asahikawa Japan
| | - Masaru Honma
- Department of Dermatology; Asahikawa Medical University; Asahikawa Japan
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19
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Bartle EI, Rao TC, Urner TM, Mattheyses AL. Bridging the gap: Super-resolution microscopy of epithelial cell junctions. Tissue Barriers 2018; 6:e1404189. [PMID: 29420122 PMCID: PMC5823550 DOI: 10.1080/21688370.2017.1404189] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 10/26/2017] [Accepted: 10/30/2017] [Indexed: 02/02/2023] Open
Abstract
Cell junctions are critical for cell adhesion and communication in epithelial tissues. It is evident that the cellular distribution, size, and architecture of cell junctions play a vital role in regulating function. These details of junction architecture have been challenging to elucidate in part due to the complexity and size of cell junctions. A major challenge in understanding these features is attaining high resolution spatial information with molecular specificity. Fluorescence microscopy allows localization of specific proteins to junctions, but with a resolution on the same scale as junction size, rendering internal protein organization unobtainable. Super-resolution microscopy provides a bridge between fluorescence microscopy and nanoscale approaches, utilizing fluorescent tags to reveal protein organization below the resolution limit. Here we provide a brief introduction to super-resolution microscopy and discuss novel findings into the organization, structure and function of epithelial cell junctions.
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Affiliation(s)
- Emily I. Bartle
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Tejeshwar C. Rao
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Tara M. Urner
- 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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20
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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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