1
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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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2
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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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3
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Perl AL, Pokorny JL, Green KJ. Desmosomes at a glance. J Cell Sci 2024; 137:jcs261899. [PMID: 38940346 PMCID: PMC11234380 DOI: 10.1242/jcs.261899] [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] [Indexed: 06/29/2024] Open
Abstract
Desmosomes are relatives of ancient cadherin-based junctions, which emerged late in evolution to ensure the structural integrity of vertebrate tissues by coupling the intermediate filament cytoskeleton to cell-cell junctions. Their ability to dynamically counter the contractile forces generated by actin-associated adherens junctions is particularly important in tissues under high mechanical stress, such as the skin and heart. Much more than the simple cellular 'spot welds' depicted in textbooks, desmosomes are in fact dynamic structures that can sense and respond to changes in their mechanical environment and external stressors like ultraviolet light and pathogens. These environmental signals are transmitted intracellularly via desmosome-dependent mechanochemical pathways that drive the physiological processes of morphogenesis and differentiation. This Cell Science at a Glance article and the accompanying poster review desmosome structure and assembly, highlight recent insights into how desmosomes integrate chemical and mechanical signaling in the epidermis, and discuss desmosomes as targets in human disease.
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Affiliation(s)
- Abbey L. Perl
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Jenny L. Pokorny
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Kathleen J. Green
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Department of Dermatology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA
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4
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Pasani S, Menon KS, Viswanath S. The molecular architecture of the desmosomal outer dense plaque by integrative structural modeling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.06.13.544884. [PMID: 37398295 PMCID: PMC10312763 DOI: 10.1101/2023.06.13.544884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Desmosomes mediate cell-cell adhesion and are prevalent in tissues under mechanical stress. However, their detailed structural characterization is not available. Here, we characterized the molecular architecture of the desmosomal outer dense plaque (ODP) using Bayesian integrative structural modeling via the Integrative Modeling Platform. Starting principally from the structural interpretation of an electron cryo-tomogram, we integrated information from X-ray crystallography, an immuno-electron microscopy study, biochemical assays, in-silico predictions of transmembrane and disordered regions, homology modeling, and stereochemistry information. The integrative structure was validated by information from imaging, tomography, and biochemical studies that were not used in modeling. The ODP resembles a densely packed cylinder with a PKP layer and a PG layer; the desmosomal cadherins and PKP span these two layers. Our integrative approach allowed us to localize disordered regions, such as N-PKP and PG-C. We refined previous protein-protein interactions between desmosomal proteins and provided possible structural hypotheses for defective cell-cell adhesion in several diseases by mapping disease-related mutations on the structure. Finally, we point to features of the structure that could confer resilience to mechanical stress. Our model provides a basis for generating experimentally verifiable hypotheses on the structure and function of desmosomal proteins in normal and disease states.
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Affiliation(s)
- Satwik Pasani
- National Center for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru 560065, India
| | - Kavya S Menon
- National Center for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru 560065, India
| | - Shruthi Viswanath
- National Center for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru 560065, India
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5
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Gupta J, Rangarajan ES, Troyanovsky RB, Indra I, Troyanovsky SM, Izard T. Plakophilin-3 Binds the Membrane and Filamentous Actin without Bundling F-Actin. Int J Mol Sci 2023; 24:9458. [PMID: 37298410 PMCID: PMC10253835 DOI: 10.3390/ijms24119458] [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: 04/28/2023] [Revised: 05/21/2023] [Accepted: 05/26/2023] [Indexed: 06/12/2023] Open
Abstract
Plakophilin-3 is a ubiquitously expressed protein found widely in epithelial cells and is a critical component of desmosomes. The plakophilin-3 carboxy-terminal domain harbors nine armadillo repeat motifs with largely unknown functions. Here, we report the 5 Å cryogenic electron microscopy (cryoEM) structure of the armadillo repeat motif domain of plakophilin-3, one of the smaller cryoEM structures reported to date. We find that this domain is a monomer or homodimer in solution. In addition, using an in vitro actin co-sedimentation assay, we show that the armadillo repeat domain of plakophilin-3 directly interacts with F-actin. This feature, through direct interactions with actin filaments, could be responsible for the observed association of extra-desmosomal plakophilin-3 with the actin cytoskeleton directly attached to the adherens junctions in A431 epithelial cells. Further, we demonstrate, through lipid binding analyses, that plakophilin-3 can effectively be recruited to the plasma membrane through phosphatidylinositol-4,5-bisphosphate-mediated interactions. Collectively, we report on novel properties of plakophilin-3, which may be conserved throughout the plakophilin protein family and may be behind the roles of these proteins in cell-cell adhesion.
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Affiliation(s)
- Jyoti Gupta
- Cell Adhesion Laboratory, UF Scripps, Jupiter, FL 33458, USA
| | | | - Regina B. Troyanovsky
- Department of Dermatology, The Feinberg School of Medicine, Northwestern University, Chicago, IL 606112, USA
| | - Indrajyoti Indra
- Department of Dermatology, The Feinberg School of Medicine, Northwestern University, Chicago, IL 606112, USA
| | - Sergey M. Troyanovsky
- Department of Dermatology, The Feinberg School of Medicine, Northwestern University, Chicago, IL 606112, USA
| | - Tina Izard
- Cell Adhesion Laboratory, UF Scripps, Jupiter, FL 33458, USA
- The Skaggs Graduate School, The Scripps Research Institute, La Jolla, CA 92037, USA
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6
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Rietscher K, Jahnke HG, Rübsam M, Lin EW, Has C, Omary MB, Niessen CM, Magin TM. Kinase Inhibition by PKC412 Prevents Epithelial Sheet Damage in Autosomal Dominant Epidermolysis Bullosa Simplex through Keratin and Cell Contact Stabilization. J Invest Dermatol 2022; 142:3282-3293. [PMID: 35691363 DOI: 10.1016/j.jid.2022.05.1088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 04/24/2022] [Accepted: 05/22/2022] [Indexed: 01/05/2023]
Abstract
Epidermolysis bullosa simplex (EBS) is a severe and potentially life-threatening disorder for which no adequate therapy exists. Most cases are caused by dominant sequence variations in keratin genes K5 or K14, leading to the formation of cytoplasmic keratin aggregates, profound keratinocyte fragility, and cytolysis. We hypothesized that pharmacological reduction of keratin aggregates, which compromise keratinocyte integrity, represents a viable strategy for the treatment of EBS. In this study, we show that the multikinase inhibitor PKC412, which is currently in clinical use for acute myeloid leukemia and advanced systemic mastocytosis, reduced keratin aggregation by 40% in patient-derived K14.R125C EBS-associated keratinocytes. Using a combination of epithelial shear stress assay and real-time impedance spectroscopy, we show that PKC412 restored intercellular adhesion. Molecularly, global phosphoproteomic analysis together with immunoblots using phosphoepitope-specific antibodies revealed that PKC412 treatment altered phosphorylated sites on keratins and desmoplakin. Thus, our data provide a proof of concept to repurpose existing drugs for the targeted treatment of EBS and showcase how one broad-range kinase inhibitor reduced keratin filament aggregation in patient-derived EBS keratinocytes and the fragility of EBS cell monolayers. Our study paves the way for a clinical trial using PKC412 for systemic or local application in patients with EBS.
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Affiliation(s)
- Katrin Rietscher
- Institute of Biology, Division of Cell and Developmental Biology, Leipzig University, Leipzig, Germany.
| | - Heinz-Georg Jahnke
- Division of Molecular Biological-Biochemical Processing Technology, Center for Biotechnology and Biomedicine, Leipzig University, Leipzig, Germany
| | - Matthias Rübsam
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany; Department Cell Biology of the Skin, Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Eric W Lin
- Division of Gastroenterology and Hepatology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Cristina Has
- Department of Dermatology, Medical Center, University of Freiburg, Freiburg, Germany
| | - M Bishr Omary
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, New Jersey, USA; Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey, USA
| | - Carien M Niessen
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany; Department Cell Biology of the Skin, Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Thomas M Magin
- Institute of Biology, Division of Cell and Developmental Biology, Leipzig University, Leipzig, Germany
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7
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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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8
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Müller L, Hatzfeld M, Keil R. Desmosomes as Signaling Hubs in the Regulation of Cell Behavior. Front Cell Dev Biol 2021; 9:745670. [PMID: 34631720 PMCID: PMC8495202 DOI: 10.3389/fcell.2021.745670] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 08/31/2021] [Indexed: 12/19/2022] Open
Abstract
Desmosomes are intercellular junctions, which preserve tissue integrity during homeostatic and stress conditions. These functions rely on their unique structural properties, which enable them to respond to context-dependent signals and transmit them to change cell behavior. Desmosome composition and size vary depending on tissue specific expression and differentiation state. Their constituent proteins are highly regulated by posttranslational modifications that control their function in the desmosome itself and in addition regulate a multitude of desmosome-independent functions. This review will summarize our current knowledge how signaling pathways that control epithelial shape, polarity and function regulate desmosomes and how desmosomal proteins transduce these signals to modulate cell behavior.
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Affiliation(s)
- Lisa Müller
- Department for Pathobiochemistry, Institute of Molecular Medicine, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Mechthild Hatzfeld
- Department for Pathobiochemistry, Institute of Molecular Medicine, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - René Keil
- Department for Pathobiochemistry, Institute of Molecular Medicine, Martin Luther University Halle-Wittenberg, Halle, Germany
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9
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Lee JYW, McGrath JA. Mutations in genes encoding desmosomal proteins: spectrum of cutaneous and extracutaneous abnormalities. Br J Dermatol 2020; 184:596-605. [PMID: 32593191 DOI: 10.1111/bjd.19342] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/20/2020] [Indexed: 12/27/2022]
Abstract
The desmosome is a type of intercellular junction found in epithelial cells, cardiomyocytes and other specialized cell types. Composed of a network of transmembranous cadherins and intracellular armadillo, plakin and other proteins, desmosomes contribute to cell-cell adhesion, signalling, development and differentiation. Mutations in genes encoding desmosomal proteins result in a spectrum of erosive skin and mucosal phenotypes that also may affect hair or heart. This review summarizes the molecular pathology and phenotypes associated with desmosomal dysfunction with a focus on inherited disorders that involve the skin/hair, as well as associated extracutaneous pathologies. We reviewed the relevant literature to collate studies of pathogenic human mutations in desmosomes that have been reported over the last 25 years. Mutations in 12 different desmosome genes have been documented, with mutations in nine genes affecting the skin/mucous membranes (DSG1, DSG3, DSC2, DSC3, JUP, PKP1, DSP, CDSN, PERP) and eight resulting in hair abnormalities (DSG4, DSC2, DSC3, JUP, PKP1, DSP, CDSN, PERP). Mutations in three genes can result in cardiocutaneous syndromes (DSC2, JUP, DSP), although mutations have been described in five genes in inherited heart disorders that may lack any dermatological manifestations (DSG2, DSC2, JUP, PKP2, DSP). Understanding the diverse nature of these clinical phenotypes, as well as the desmosome gene mutation(s), has clinical value in managing and counselling patients, as well as demonstrating the biological role and activity of specific components of desmosomes in skin and other tissues.
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Affiliation(s)
- J Y W Lee
- St John's Institute of Dermatology, King's College London, Guy's Hospital, London, UK
| | - J A McGrath
- St John's Institute of Dermatology, King's College London, Guy's Hospital, London, UK
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10
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Arrhythmogenic Cardiomyopathy: Molecular Insights for Improved Therapeutic Design. J Cardiovasc Dev Dis 2020; 7:jcdd7020021. [PMID: 32466575 PMCID: PMC7345706 DOI: 10.3390/jcdd7020021] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 05/17/2020] [Accepted: 05/20/2020] [Indexed: 02/07/2023] Open
Abstract
Arrhythmogenic cardiomyopathy (ACM) is an inherited disorder characterized by structural and electrical cardiac abnormalities, including myocardial fibro-fatty replacement. Its pathological ventricular substrate predisposes subjects to an increased risk of sudden cardiac death (SCD). ACM is a notorious cause of SCD in young athletes, and exercise has been documented to accelerate its progression. Although the genetic culprits are not exclusively limited to the intercalated disc, the majority of ACM-linked variants reside within desmosomal genes and are transmitted via Mendelian inheritance patterns; however, penetrance is highly variable. Its natural history features an initial “concealed phase” that results in patients being vulnerable to malignant arrhythmias prior to the onset of structural changes. Lack of effective therapies that target its pathophysiology renders management of patients challenging due to its progressive nature, and has highlighted a critical need to improve our understanding of its underlying mechanistic basis. In vitro and in vivo studies have begun to unravel the molecular consequences associated with disease causing variants, including altered Wnt/β-catenin signaling. Characterization of ACM mouse models has facilitated the evaluation of new therapeutic approaches. Improved molecular insight into the condition promises to usher in novel forms of therapy that will lead to improved care at the clinical bedside.
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11
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Zhao G, Zhang HM, Qiu Y, Ye X, Yang D. Cleavage of Desmosomal Cadherins Promotes γ-Catenin Degradation and Benefits Wnt Signaling in Coxsackievirus B3-Induced Destruction of Cardiomyocytes. Front Microbiol 2020; 11:767. [PMID: 32457708 PMCID: PMC7225294 DOI: 10.3389/fmicb.2020.00767] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 03/31/2020] [Indexed: 01/01/2023] Open
Abstract
Coxsackievirus B3 (CVB3) is the primary etiologic agent of viral myocarditis, a major heart disease that occurs predominantly in children and young adolescents. In the heart, intercalated disks (ICD) are important structural formations that connect adjacent cardiomyocytes to maintain cardiac architecture and mediate signal communication. Deficiency in ICD components, such as desmosome proteins, leads to heart dysfunction. γ-catenin, a component protein of desmosomes, normally binds directly to desmocollin-2 and desmoglein-2. In this study, we found that CVB3 infection downregulated γ-catenin at the protein level but not the mRNA level in mouse HL-1 cardiomyocytes. We further found that this reduction of γ-catenin protein is a result of ubiquitin proteasome-mediated degradation, since the addition of proteasome inhibitor MG132 inhibited γ-catenin downregulation. In addition, we found that desmocollin-2 and desmoglein-2 were cleaved by both viral protease 3C and virus-activated cellular caspase, respectively. These cleavages led to the release of bound γ-catenin from the desmosome into the cytosol, resulting in rapid degradation of γ-catenin. Since γ-catenin shares high sequence homology with β-catenin in binding the TCF/LEF transcription factor, we further studied the effect of γ-catenin degradation on Wnt/β-catenin signaling. Luciferase assay showed that γ-catenin expression inhibited Wnt/β-catenin signaling. This finding was substantiated by qPCR to show that overexpression of γ-catenin downregulated transcription of Wnt signal target genes, c-myc and MMP9, while silencing γ-catenin upregulated these target genes. Finally, we demonstrated that γ-catenin expression inhibited CVB3 replication. In search for the underlying mechanism, we found that silencing γ-catenin caused down-regulation of interferon-β and its stimulated antiviral genes MDA5, MAVS, and ISG15. Taken together, our results indicate, for the first time, that CVB3 infection causes cardiomyocyte death through, at least in part, direct damage to the desmosome structure and reduction of γ-catenin protein, which in return promotes Wnt/β-catenin signaling and downregulates interferon-β stimulated immune responses.
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Affiliation(s)
- Guangze Zhao
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.,Centre for Heart Lung Innovation, St. Paul's Hospital, Vancouver, BC, Canada
| | - Huifang M Zhang
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.,Centre for Heart Lung Innovation, St. Paul's Hospital, Vancouver, BC, Canada
| | - Ye Qiu
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.,College of Biology, Hunan University, Changsha, China
| | - Xin Ye
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.,Centre for Heart Lung Innovation, St. Paul's Hospital, Vancouver, BC, Canada
| | - Decheng Yang
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.,Centre for Heart Lung Innovation, St. Paul's Hospital, Vancouver, BC, Canada
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12
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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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13
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Moch M, Schwarz N, Windoffer R, Leube RE. The keratin-desmosome scaffold: pivotal role of desmosomes for keratin network morphogenesis. Cell Mol Life Sci 2020; 77:543-558. [PMID: 31243490 PMCID: PMC7010626 DOI: 10.1007/s00018-019-03198-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 05/09/2019] [Accepted: 06/17/2019] [Indexed: 11/29/2022]
Abstract
Desmosome-anchored keratin intermediate filaments (KFs) are essential for epithelial coherence. Yet, desmosomal KF attachment and network organization are still unexplored in vivo. We, therefore, monitored KF network morphogenesis in fluorescent keratin 8 knock-in murine embryos revealing keratin enrichment at newly formed desmosomes followed by KF formation, KF elongation and KF fusion. To examine details of this process and its coupling to desmosome formation, we studied fluorescent keratin and desmosomal protein reporter dynamics in the periphery of expanding HaCaT keratinocyte colonies. Less than 3 min after the start of desmosomal proteins clustering non-filamentous keratin enriched at these sites followed by KF formation and elongation. Subsequently, desmosome-anchored KFs merged into stable bundles generating a rim-and-spokes system consisting of subcortical KFs connecting desmosomes to each other and radial KFs connecting desmosomes to the cytoplasmic KF network. We conclude that desmosomes are organizing centers for the KF cytoskeleton with a hitherto unknown nucleation capacity.
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Affiliation(s)
- Marcin Moch
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Wendlingweg 2, 52074, Aachen, Germany
| | - Nicole Schwarz
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Wendlingweg 2, 52074, Aachen, Germany
| | - Reinhard Windoffer
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Wendlingweg 2, 52074, Aachen, Germany
| | - Rudolf E Leube
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Wendlingweg 2, 52074, Aachen, Germany.
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14
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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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15
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Favre B, Begré N, Bouameur JE, Lingasamy P, Conover GM, Fontao L, Borradori L. Desmoplakin interacts with the coil 1 of different types of intermediate filament proteins and displays high affinity for assembled intermediate filaments. PLoS One 2018; 13:e0205038. [PMID: 30286183 PMCID: PMC6171917 DOI: 10.1371/journal.pone.0205038] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 09/18/2018] [Indexed: 12/04/2022] Open
Abstract
The interaction of intermediate filaments (IFs) with the cell-cell adhesion complexes desmosomes is crucial for cytoskeletal organization and cell resilience in the epidermis and heart. The intracellular desmosomal protein desmoplakin anchors IFs to the cell adhesion complexes predominantly via its four last carboxy-terminal domains (C-terminus). However, it remains unclear why the C-terminus of desmoplakin interacts with different IF types or if there are different binding affinities for each type of IFs that may influence the stability of cell-specific adhesion complexes. By yeast three-hybrid and fluorescence binding assays, we found that the coiled-coil 1 of the conserved central rod domain of the heterodimeric cytokeratins (Ks) 5 and 14 (K5/K14) was required for their interaction with the C-terminus of desmoplakin, while their unique amino head- and C-tail domains were dispensable. Similar findings were obtained in vitro with K1/K10, and the type III IF proteins desmin and vimentin. Binding assays testing the C-terminus of desmoplakin with assembled K5/K14 and desmin IFs yielded an apparent affinity in the nM range. Our findings reveal that the same conserved domain of IF proteins binds to the C-terminus of desmoplakin, which may help explain the previously reported broad binding IF-specificity to desmoplakin. Our data suggest that desmoplakin high-affinity binding to diverse IF proteins ensures robust linkages of IF cytoskeleton and desmosomes that maintain the structural integrity of cellular adhesion complexes. In summary, our results give new insights into the molecular basis of the IF-desmosome association.
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Affiliation(s)
- Bertrand Favre
- Department of Dermatology, Inselspital, Bern University Hospital, Bern, Switzerland
- Department for Biomedical Research, University of Bern, Bern, Switzerland
| | - Nadja Begré
- Department of Dermatology, Inselspital, Bern University Hospital, Bern, Switzerland
- Department for Biomedical Research, University of Bern, Bern, Switzerland
| | - Jamal-Eddine Bouameur
- Department of Dermatology, Inselspital, Bern University Hospital, Bern, Switzerland
- Department for Biomedical Research, University of Bern, Bern, Switzerland
| | - Prakash Lingasamy
- Department of Dermatology, Inselspital, Bern University Hospital, Bern, Switzerland
- Department for Biomedical Research, University of Bern, Bern, Switzerland
| | - Gloria M. Conover
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas, United States of America
| | - Lionel Fontao
- Department of Dermatology, Geneva University Hospitals, Geneva, Switzerland
| | - Luca Borradori
- Department of Dermatology, Inselspital, Bern University Hospital, Bern, Switzerland
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16
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Hatzfeld M, Keil R, Magin TM. Desmosomes and Intermediate Filaments: Their Consequences for Tissue Mechanics. Cold Spring Harb Perspect Biol 2017; 9:a029157. [PMID: 28096266 PMCID: PMC5453391 DOI: 10.1101/cshperspect.a029157] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Adherens junctions (AJs) and desmosomes connect the actin and keratin filament networks of adjacent cells into a mechanical unit. Whereas AJs function in mechanosensing and in transducing mechanical forces between the plasma membrane and the actomyosin cytoskeleton, desmosomes and intermediate filaments (IFs) provide mechanical stability required to maintain tissue architecture and integrity when the tissues are exposed to mechanical stress. Desmosomes are essential for stable intercellular cohesion, whereas keratins determine cell mechanics but are not involved in generating tension. Here, we summarize the current knowledge of the role of IFs and desmosomes in tissue mechanics and discuss whether the desmosome-keratin scaffold might be actively involved in mechanosensing and in the conversion of chemical signals into mechanical strength.
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Affiliation(s)
- Mechthild Hatzfeld
- Institute of Molecular Medicine, Division of Pathobiochemistry, Martin-Luther-University Halle-Wittenberg, 06114 Halle, Germany
| | - René Keil
- Institute of Molecular Medicine, Division of Pathobiochemistry, Martin-Luther-University Halle-Wittenberg, 06114 Halle, Germany
| | - Thomas M Magin
- Institute of Biology, Division of Cell and Developmental Biology and Saxonian Incubator for Clinical Translation (SIKT), University of Leipzig, 04103 Leipzig, Germany
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17
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Jones JCR, Kam CY, Harmon RM, Woychek AV, Hopkinson SB, Green KJ. Intermediate Filaments and the Plasma Membrane. Cold Spring Harb Perspect Biol 2017; 9:9/1/a025866. [PMID: 28049646 DOI: 10.1101/cshperspect.a025866] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
A variety of intermediate filament (IF) types show intricate association with plasma membrane proteins, including receptors and adhesion molecules. The molecular basis of linkage of IFs to desmosomes at sites of cell-cell interaction and hemidesmosomes at sites of cell-matrix adhesion has been elucidated and involves IF-associated proteins. However, IFs also interact with focal adhesions and cell-surface molecules, including dystroglycan. Through such membrane interactions, it is well accepted that IFs play important roles in the establishment and maintenance of tissue integrity. However, by organizing cell-surface complexes, IFs likely regulate, albeit indirectly, signaling pathways that are key to tissue homeostasis and repair.
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Affiliation(s)
- Jonathan C R Jones
- The School of Molecular Biosciences, Washington State University, Pullman, Washington 99164
| | - Chen Yuan Kam
- Departments of Dermatology and Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Robert M Harmon
- Departments of Dermatology and Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Alexandra V Woychek
- The School of Molecular Biosciences, Washington State University, Pullman, Washington 99164
| | - Susan B Hopkinson
- The School of Molecular Biosciences, Washington State University, Pullman, Washington 99164
| | - Kathleen J Green
- Departments of Dermatology and Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
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18
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Celentano A, Mignogna MD, McCullough M, Cirillo N. Pathophysiology of the Desmo-Adhesome. J Cell Physiol 2016; 232:496-505. [PMID: 27505028 DOI: 10.1002/jcp.25515] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 08/08/2016] [Indexed: 01/18/2023]
Abstract
Advances in our understanding of desmosomal diseases have provided a clear demonstration of the key role played by desmosomes in tissue and organ physiology, highlighting the importance of their dynamic and finely regulated structure. In this context, non-desmosomal regulatory molecules have acquired increasing relevance in the study of this organelle resulting in extending the desmosomal interactome, named the "desmo-adhesome." Spatiotemporal changes in the expression and regulation of the desmo-adhesome underlie a number of genetic, infectious, autoimmune, and malignant conditions. The aim of the present article was to examine the structural and functional relationship of the desmosome, by providing a comprehensive, yet focused overview of the constituents targeted in human disease. The inclusion of the novel regulatory network in the desmo-adhesome pathophysiology opens new avenues to a deeper understanding of desmosomal diseases, potentially unveiling pathogenic mechanisms waiting to be explored. J. Cell. Physiol. 232: 496-505, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Antonio Celentano
- Department of Neurosciences, Reproductive and Odontostomatological Sciences, University Federico II of Naples, Naples, Italy.,Melbourne Dental School, University of Melbourne, Carlton, Victoria, Australia
| | - Michele Davide Mignogna
- Department of Neurosciences, Reproductive and Odontostomatological Sciences, University Federico II of Naples, Naples, Italy
| | - Michael McCullough
- Melbourne Dental School, University of Melbourne, Carlton, Victoria, Australia.,Oral Health Cooperative Research Centre (CRC), University of Melbourne, Carlton, Victoria, Australia
| | - Nicola Cirillo
- Melbourne Dental School, University of Melbourne, Carlton, Victoria, Australia.,Oral Health Cooperative Research Centre (CRC), University of Melbourne, Carlton, Victoria, Australia
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19
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Rietscher K, Wolf A, Hause G, Rother A, Keil R, Magin TM, Glass M, Niessen CM, Hatzfeld M. Growth Retardation, Loss of Desmosomal Adhesion, and Impaired Tight Junction Function Identify a Unique Role of Plakophilin 1 In Vivo. J Invest Dermatol 2016; 136:1471-1478. [DOI: 10.1016/j.jid.2016.03.021] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 03/07/2016] [Accepted: 03/08/2016] [Indexed: 12/12/2022]
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20
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Keil R, Rietscher K, Hatzfeld M. Antagonistic Regulation of Intercellular Cohesion by Plakophilins 1 and 3. J Invest Dermatol 2016; 136:2022-2029. [PMID: 27375112 DOI: 10.1016/j.jid.2016.05.124] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 04/26/2016] [Accepted: 05/29/2016] [Indexed: 11/18/2022]
Abstract
Desmosomes are cell-cell adhesive structures essential for tissue integrity of the epidermis and the heart. Their constituents belong to multigene families giving rise to desmosomes of variable composition. So far, the functional significance of context-dependent composition in desmosome formation, dynamics, or stability during epidermal differentiation is incompletely understood. In this comparative study, we have uncovered unique and partially antagonistic functions of plakophilins 1 and 3 that are both expressed in the murine epidermis. These plakophilins differ in their localization patterns and kinetics during de novo desmosome formation and are regulated by distinct mechanisms. Moreover, plakophilin 3-containing desmosomes are more dynamic than desmosomes that contain predominantly plakophilin 1. Further, we show that Ca(2+)-independence of desmosomes strictly depends on plakophilin 1, whereas elevated levels of plakophilin 3 prevent the formation of hyperadhesive desmosomes in a protein kinase C alpha-dependent manner, even in the presence of plakophilin 1. Our study demonstrates that the balance between plakophilins 1 and 3 determines the context-dependent properties of epidermal desmosomes. In this setting, plakophilin 1 provides stable intercellular cohesion that resists mechanical stress, whereas plakophilin 3 confers dynamics as required during tissue homeostasis and repair. Our data have implications for the role of plakophilins in carcinogenesis.
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Affiliation(s)
- René Keil
- Institute of Molecular Medicine, Division of Pathobiochemistry, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Katrin Rietscher
- Institute of Molecular Medicine, Division of Pathobiochemistry, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Mechthild Hatzfeld
- Institute of Molecular Medicine, Division of Pathobiochemistry, Martin-Luther-University Halle-Wittenberg, Halle, Germany.
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21
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22
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McAleer MA, Pohler E, Smith FJD, Wilson NJ, Cole C, MacGowan S, Koetsier JL, Godsel LM, Harmon RM, Gruber R, Crumrine D, Elias PM, McDermott M, Butler K, Broderick A, Sarig O, Sprecher E, Green KJ, McLean WHI, Irvine AD. Severe dermatitis, multiple allergies, and metabolic wasting syndrome caused by a novel mutation in the N-terminal plakin domain of desmoplakin. J Allergy Clin Immunol 2015; 136:1268-76. [PMID: 26073755 PMCID: PMC4649901 DOI: 10.1016/j.jaci.2015.05.002] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 05/01/2015] [Accepted: 05/02/2015] [Indexed: 11/19/2022]
Abstract
Background Severe dermatitis, multiple allergies, and metabolic wasting (SAM) syndrome is a recently recognized syndrome caused by mutations in the desmoglein 1 gene (DSG1). To date, only 3 families have been reported. Objective We studied a new case of SAM syndrome known to have no mutations in DSG1 to detail the clinical, histopathologic, immunofluorescent, and ultrastructural phenotype and to identify the underlying molecular mechanisms in this rare genodermatosis. Methods Histopathologic, electron microscopy, and immunofluorescent studies were performed. Whole-exome sequencing data were interrogated for mutations in desmosomal and other skin structural genes, followed by Sanger sequencing of candidate genes in the patient and his parents. Results No mutations were identified in DSG1; however, a novel de novo heterozygous missense c.1757A>C mutation in the desmoplakin gene (DSP) was identified in the patient, predicting the amino acid substitution p.His586Pro in the desmoplakin polypeptide. Conclusions SAM syndrome can be caused by mutations in both DSG1 and DSP. Knowledge of this genetic heterogeneity is important for both analysis of patients and genetic counseling of families. This condition and these observations reinforce the importance of heritable skin barrier defects, in this case desmosomal proteins, in the pathogenesis of atopic disease.
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Affiliation(s)
- Maeve A McAleer
- Clinical Medicine, Trinity College Dublin, Dublin, Ireland; Pediatric Dermatology, Our Lady's Children's Hospital Crumlin, Dublin, Ireland; National Children's Research Centre, Our Lady's Children's Hospital Crumlin, Dublin, Ireland
| | - Elizabeth Pohler
- Dermatology and Genetic Medicine, University of Dundee, Dundee, United Kingdom
| | - Frances J D Smith
- Dermatology and Genetic Medicine, University of Dundee, Dundee, United Kingdom
| | - Neil J Wilson
- Dermatology and Genetic Medicine, University of Dundee, Dundee, United Kingdom
| | - Christian Cole
- Division of Computational Biology, College of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Stuart MacGowan
- Division of Computational Biology, College of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Jennifer L Koetsier
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, Ill
| | - Lisa M Godsel
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, Ill; Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, Ill
| | - Robert M Harmon
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, Ill
| | - Robert Gruber
- Department of Dermatology and Venereology, Innsbruck Medical University, Innsbruck, Austria
| | - Debra Crumrine
- Dermatology Service, Veterans Affairs Medical Center, San Francisco, and the Department of Dermatology, University of California, San Francisco, Calif
| | - Peter M Elias
- Dermatology Service, Veterans Affairs Medical Center, San Francisco, and the Department of Dermatology, University of California, San Francisco, Calif
| | - Michael McDermott
- National Children's Research Centre, Our Lady's Children's Hospital Crumlin, Dublin, Ireland
| | - Karina Butler
- Infectious Disease Department, Our Lady's Children's Hospital Crumlin, Dublin, Ireland
| | - Annemarie Broderick
- Department of Gastroenterology, Our Lady's Children's Hospital Crumlin and School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
| | - Ofer Sarig
- Department of Dermatology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel; Department of Human Molecular Genetics & Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Eli Sprecher
- Department of Gastroenterology, Our Lady's Children's Hospital Crumlin and School of Medicine and Medical Science, University College Dublin, Dublin, Ireland; Department of Dermatology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel; Department of Human Molecular Genetics & Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Kathleen J Green
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, Ill; Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, Ill
| | - W H Irwin McLean
- Dermatology and Genetic Medicine, University of Dundee, Dundee, United Kingdom
| | - Alan D Irvine
- Clinical Medicine, Trinity College Dublin, Dublin, Ireland; Pediatric Dermatology, Our Lady's Children's Hospital Crumlin, Dublin, Ireland; National Children's Research Centre, Our Lady's Children's Hospital Crumlin, Dublin, Ireland.
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23
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Fujiwara M, Nagatomo A, Tsuda M, Obata S, Sakuma T, Yamamoto T, Suzuki ST. Desmocollin-2 alone forms functional desmosomal plaques, with the plaque formation requiring the juxtamembrane region and plakophilins. J Biochem 2015; 158:339-53. [DOI: 10.1093/jb/mvv048] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2015] [Accepted: 04/09/2015] [Indexed: 01/04/2023] Open
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24
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iASPP, a previously unidentified regulator of desmosomes, prevents arrhythmogenic right ventricular cardiomyopathy (ARVC)-induced sudden death. Proc Natl Acad Sci U S A 2015; 112:E973-81. [PMID: 25691752 DOI: 10.1073/pnas.1408111112] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Desmosomes are anchoring junctions that exist in cells that endure physical stress such as cardiac myocytes. The importance of desmosomes in maintaining the homeostasis of the myocardium is underscored by frequent mutations of desmosome components found in human patients and animal models. Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a phenotype caused by mutations in desmosomal components in ∼ 50% of patients, however, the causes in the remaining 50% of patients still remain unknown. A deficiency of inhibitor of apoptosis-stimulating protein of p53 (iASPP), an evolutionarily conserved inhibitor of p53, caused by spontaneous mutation recently has been associated with a lethal autosomal recessive cardiomyopathy in Poll Hereford calves and Wa3 mice. However, the molecular mechanisms that mediate this putative function of iASPP are completely unknown. Here, we show that iASPP is expressed at intercalated discs in human and mouse postmitotic cardiomyocytes. iASPP interacts with desmoplakin and desmin in cardiomyocytes to maintain the integrity of desmosomes and intermediate filament networks in vitro and in vivo. iASPP deficiency specifically induces right ventricular dilatation in mouse embryos at embryonic day 16.5. iASPP-deficient mice with exon 8 deletion (Ppp1r13l(Δ8/Δ8)) die of sudden cardiac death, displaying features of ARVC. Intercalated discs in cardiomyocytes from four of six human ARVC cases show reduced or loss of iASPP. ARVC-derived desmoplakin mutants DSP-1-V30M and DSP-1-S299R exhibit weaker binding to iASPP. These data demonstrate that by interacting with desmoplakin and desmin, iASPP is an important regulator of desmosomal function both in vitro and in vivo. This newly identified property of iASPP may provide new molecular insight into the pathogenesis of ARVC.
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25
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Abstract
Cell-cell adhesions are necessary for structural integrity and barrier formation of the epidermis. Here, we discuss insights from genetic and cell biological studies into the roles of individual cell-cell junctions and their composite proteins in regulating epidermal development and function. In addition to individual adhesive functions, we will discuss emerging ideas on mechanosensation/transduction of junctions in the epidermis, noncanonical roles for adhesion proteins, and crosstalk/interdependencies between the junctional systems. These studies have revealed that cell adhesion proteins are connected to many aspects of tissue physiology including growth control, differentiation, and inflammation.
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Affiliation(s)
- Kaelyn D Sumigray
- Department of Dermatology, Duke University Medical Center, Durham, North Carolina, USA; Department of Cell Biology, Duke University Medical Center, Durham, North Carolina, USA
| | - Terry Lechler
- Department of Dermatology, Duke University Medical Center, Durham, North Carolina, USA; Department of Cell Biology, Duke University Medical Center, Durham, North Carolina, USA.
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26
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Abstract
Desmosomes serve as intercellular junctions in various tissues including the skin and the heart where they play a crucial role in cell-cell adhesion, signalling and differentiation. The desmosomes connect the cell surface to the keratin cytoskeleton and are composed of a transmembranal part consisting mainly of desmosomal cadherins, armadillo proteins and desmoplakin, which form the intracytoplasmic desmosomal plaque. Desmosomal genodermatoses are caused by mutations in genes encoding the various desmosomal components. They are characterized by skin, hair and cardiac manifestations occurring in diverse combinations. Their classification into a separate and distinct clinical group not only recognizes their common pathogenesis and facilitates their diagnosis but might also in the future form the basis for the design of novel and targeted therapies for these occasionally life-threatening diseases.
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27
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Patel DM, Dubash AD, Kreitzer G, Green KJ. Disease mutations in desmoplakin inhibit Cx43 membrane targeting mediated by desmoplakin-EB1 interactions. ACTA ACUST UNITED AC 2014; 206:779-97. [PMID: 25225338 PMCID: PMC4164953 DOI: 10.1083/jcb.201312110] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Mechanisms by which microtubule plus ends interact with regions of cell-cell contact during tissue development and morphogenesis are not fully understood. We characterize a previously unreported interaction between the microtubule binding protein end-binding 1 (EB1) and the desmosomal protein desmoplakin (DP), and demonstrate that DP-EB1 interactions enable DP to modify microtubule organization and dynamics near sites of cell-cell contact. EB1 interacts with a region of the DP N terminus containing a hotspot for pathogenic mutations associated with arrhythmogenic cardiomyopathy (AC). We show that a subset of AC mutations, in addition to a mutation associated with skin fragility/woolly hair syndrome, impair gap junction localization and function by misregulating DP-EB1 interactions and altering microtubule dynamics. This work identifies a novel function for a desmosomal protein in regulating microtubules that affect membrane targeting of gap junction components, and elucidates a mechanism by which DP mutations may contribute to the development of cardiac and cutaneous diseases.
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Affiliation(s)
- Dipal M Patel
- Department of Pathology and Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - Adi D Dubash
- Department of Pathology and Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - Geri Kreitzer
- Department of Cell and Developmental Biology, Weill Cornell Medical College of Cornell University, New York, NY 10065
| | - Kathleen J Green
- Department of Pathology and Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611 Department of Pathology and Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
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28
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Abstract
Desmosomes are morphologically and biochemically defined cell-cell junctions that are required for maintaining the mechanical integrity of skin and the heart in adult mammals. Furthermore, since mice with null mutations in desmosomal plaque proteins (plakoglobin and desmoplakin) die in utero, it is also evident that desmosomes are indispensable for normal embryonic development. This review focuses on the role of desmosomes in vivo. We will summarize the effects of mutations in desmosomal genes on pre- and post-embryonic development of mouse and man and discuss recent findings relating to the specific role of desmosomal cadherins in skin differentiation and homeostasis.
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Affiliation(s)
- Xing Cheng
- Department of Dermatology, Baylor College of Medicine, Houston, TX 77030, USA
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29
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Munoz WA, Lee M, Miller RK, Ahmed Z, Ji H, Link TM, Lee GR, Kloc M, Ladbury JE, McCrea PD. Plakophilin-3 catenin associates with the ETV1/ER81 transcription factor to positively modulate gene activity. PLoS One 2014; 9:e86784. [PMID: 24475179 PMCID: PMC3903613 DOI: 10.1371/journal.pone.0086784] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Accepted: 12/13/2013] [Indexed: 12/31/2022] Open
Abstract
Members of the plakophilin-catenin sub-family (Pkp-1, -2, and -3) facilitate the linkage of desmosome junctional components to each other (e.g. desmosomal cadherins to desmoplakin) and the intermediate-filament cytoskeleton. Pkps also contribute to desmosomal stabilization and the trafficking of its components. The functions of Pkps outside of the desmosome are less well studied, despite evidence suggesting their roles in mRNA regulation, small-GTPase modulation (e.g. mid-body scission) during cell division, and cell survival following DNA damage. Pkp-catenins are further believed to have roles in the nucleus given their nuclear localization in some contexts and the known nuclear roles of structurally related catenins, such as beta-catenin and p120-catenin. Further, Pkp-catenin activities in the nuclear compartment have become of increased interest with the identification of interactions between Pkp2-catenin and RNA Pol III and Pkp1 with single-stranded DNA. Consistent with earlier reports suggesting possible nuclear roles in development, we previously demonstrated prominent nuclear localization of Pkp3 in Xenopus naïve ectoderm (“animal cap”) cells and recently resolved a similar localization in mouse embryonic stem cells. Here, we report the association and positive functional interaction of Pkp3 with a transcription factor, Ets variant gene 1 (ETV1), which has critical roles in neural development and prominent roles in human genetic disease. Our results are the first to report the interaction of a sequence-specific transcription factor with any Pkp. Using Xenopus laevis embryos and mammalian cells, we provide evidence for the Pkp3:ETV1 complex on both biochemical and functional levels.
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Affiliation(s)
- William A. Munoz
- Department of Biochemistry and Molecular Biology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
- Program in Genes & Development, The University of Texas Graduate School of Biomedical Science - Houston, Texas, United States of America
| | - Moonsup Lee
- Department of Biochemistry and Molecular Biology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
- Program in Genes & Development, The University of Texas Graduate School of Biomedical Science - Houston, Texas, United States of America
| | - Rachel K. Miller
- Department of Biochemistry and Molecular Biology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Zamal Ahmed
- Department of Biochemistry and Molecular Biology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
- Center for Biomolecular Structure and Function, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Hong Ji
- Department of Biochemistry and Molecular Biology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Todd M. Link
- Department of Biochemistry and Molecular Biology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
- Center for Biomolecular Structure and Function, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Gilbert R. Lee
- Department of Biochemistry and Molecular Biology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
- Center for Biomolecular Structure and Function, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Malgorzata Kloc
- Department of Biochemistry and Molecular Biology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
- Department of Surgery, Houston Methodist, Houston Methodist Research Institute, Houston, Texas, United States of America
| | - John E. Ladbury
- Department of Biochemistry and Molecular Biology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
- Program in Genes & Development, The University of Texas Graduate School of Biomedical Science - Houston, Texas, United States of America
- Center for Biomolecular Structure and Function, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Pierre D. McCrea
- Department of Biochemistry and Molecular Biology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
- Program in Genes & Development, The University of Texas Graduate School of Biomedical Science - Houston, Texas, United States of America
- * E-mail:
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30
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Abstract
Desmosomes anchor intermediate filaments at sites of cell contact established by the interaction of cadherins extending from opposing cells. The incorporation of cadherins, catenin adaptors, and cytoskeletal elements resembles the closely related adherens junction. However, the recruitment of intermediate filaments distinguishes desmosomes and imparts a unique function. By linking the load-bearing intermediate filaments of neighboring cells, desmosomes create mechanically contiguous cell sheets and, in so doing, confer structural integrity to the tissues they populate. This trait and a well-established role in human disease have long captured the attention of cell biologists, as evidenced by a publication record dating back to the mid-1860s. Likewise, emerging data implicating the desmosome in signaling events pertinent to organismal development, carcinogenesis, and genetic disorders will secure a prominent role for desmosomes in future biological and biomedical investigations.
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Affiliation(s)
- Robert M Harmon
- Department of Pathology, Northwestern University Feinberg, School of Medicine , Chicago, IL , USA
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31
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Tucker DK, Stahley SN, Kowalczyk AP. Plakophilin-1 protects keratinocytes from pemphigus vulgaris IgG by forming calcium-independent desmosomes. J Invest Dermatol 2013; 134:1033-1043. [PMID: 24056861 PMCID: PMC3961504 DOI: 10.1038/jid.2013.401] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 08/22/2013] [Accepted: 09/09/2013] [Indexed: 12/16/2022]
Abstract
Plakophilin-1 (PKP-1) is an armadillo family protein critical for desmosomal adhesion and epidermal integrity. In the autoimmune skin-blistering disease pemphigus vulgaris (PV), autoantibodies (IgG) target the desmosomal cadherin desmoglein 3 (Dsg3) and compromise keratinocyte cell-cell adhesion. Here, we report that enhanced expression of PKP-1 protects keratinocytes from PV IgG-induced loss of cell-cell adhesion. PKP-1 prevents loss of Dsg3 and other desmosomal proteins from cell-cell borders and prevents alterations in desmosome ultrastructure in keratinocytes treated with PV IgG. Using a series of Dsg3 chimeras and deletion constructs, we find that PKP-1 clusters Dsg3 with the desmosomal plaque protein desmoplakin in a manner dependent on the plakoglobin-binding domain of the Dsg3 tail. Furthermore, PKP-1 expression transforms desmosome adhesion from a calcium-dependent to a calcium-independent and hyperadhesive state. These results demonstrate that manipulating the expression of a single desmosomal plaque protein can block the pathogenic effects of PV IgG on keratinocyte adhesion.
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Affiliation(s)
- Dana K Tucker
- Department of Cell Biology, Emory University, Atlanta, Georgia, USA; Graduate Program in Biochemistry, Cell, and Developmental Biology, Emory University, Atlanta, Georgia, USA
| | - Sara N Stahley
- Department of Cell Biology, Emory University, Atlanta, Georgia, USA; Graduate Program in Biochemistry, Cell, and Developmental Biology, Emory University, Atlanta, Georgia, USA
| | - Andrew P Kowalczyk
- Department of Cell Biology, Emory University, Atlanta, Georgia, USA; Department of Dermatology, Emory University, Atlanta, Georgia, USA; Winship Cancer Institute, Emory University, Atlanta, Georgia, USA.
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32
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Nekrasova O, Green KJ. Desmosome assembly and dynamics. Trends Cell Biol 2013; 23:537-46. [PMID: 23891292 DOI: 10.1016/j.tcb.2013.06.004] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 06/14/2013] [Accepted: 06/17/2013] [Indexed: 01/06/2023]
Abstract
Desmosomes are intercellular junctions that anchor intermediate filaments (IFs) to the plasma membrane, forming a supracellular scaffold that provides mechanical resilience to tissues. This anchoring function is accomplished by specialized members of the cadherin family and associated cytoskeletal linking proteins, which together form a highly organized membrane core flanked by mirror-image cytoplasmic plaques. Due to the biochemical insolubility of desmosomes, the mechanisms that govern assembly of these components into a functional organelle remained elusive. Recently developed molecular reporters and live cell imaging approaches have provided powerful new tools to monitor this finely tuned process in real time. Here we discuss studies that are beginning to decipher the machinery and regulation governing desmosome assembly and homeostasis in situ and how these mechanisms are affected during disease pathogenesis.
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Affiliation(s)
- Oxana Nekrasova
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
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33
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Abstract
Desmoglein-1 (DSG1), a desmosomal protein, maintains the structure of epidermis through its adhesive function. However, heterozygous mutations in DSG1 in humans result in abnormal differentiation, as does downregulation of DSG1 in human skin organ culture, suggesting that it may have important signaling functions. In this issue of the JCI, Harmon et al. elucidate how the binding of the DSG1 cytoplasmic tail to the scaffolding protein Erbin decreases signaling through the Ras-Raf pathway to promote stratification and differentiation of keratinocytes in the epidermis.
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Affiliation(s)
- Christoph M Hammers
- Department of Dermatology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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34
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Wolf A, Rietscher K, Glaß M, Hüttelmaier S, Schutkowski M, Ihling C, Sinz A, Wingenfeld A, Mun A, Hatzfeld M. Insulin signaling via Akt2 switches plakophilin 1 function from stabilizing cell adhesion to promoting cell proliferation. J Cell Sci 2013; 126:1832-44. [PMID: 23444369 DOI: 10.1242/jcs.118992] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Downregulation of adherens junction proteins is a frequent event in carcinogenesis. How desmosomal proteins contribute to tumor formation by regulating the balance between adhesion and proliferation is not well understood. The desmosomal protein plakophilin 1 can increase intercellular adhesion by recruiting desmosomal proteins to the plasma membrane or stimulate proliferation by enhancing translation rates. Here, we show that these dual functions of plakophilin 1 are regulated by growth factor signaling. Insulin stimulation induced the phosphorylation of plakophilin 1, which correlated with reduced intercellular adhesion and an increased activity of plakophilin 1 in the stimulation of translation. Phosphorylation was mediated by Akt2 at four motifs within the plakophilin 1 N-terminal domain. A plakophilin 1 phospho-mimetic mutant revealed reduced intercellular adhesion and accumulated in the cytoplasm, where it increased translation and proliferation rates and conferred the capacity of anchorage-independent growth. The cytoplasmic accumulation was mediated by the stabilization of phosphorylated plakophilin 1, which displayed a considerably increased half-life, whereas non-phosphorylated plakophilin 1 was more rapidly degraded. Our data indicate that upon activation of growth factor signaling, plakophilin 1 switches from a desmosome-associated growth-inhibiting to a cytoplasmic proliferation-promoting function. This supports the view that the deregulation of plakophilin 1, as observed in several tumors, directly contributes to hyperproliferation and carcinogenesis in a context-dependent manner.
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Affiliation(s)
- Annika Wolf
- Institute of Molecular Medicine, Division of Pathobiochemistry, Martin-Luther-University Halle-Wittenberg, 06114 Halle, Germany
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35
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Kowalczyk AP, Green KJ. Structure, function, and regulation of desmosomes. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 116:95-118. [PMID: 23481192 DOI: 10.1016/b978-0-12-394311-8.00005-4] [Citation(s) in RCA: 160] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Desmosomes are adhesive intercellular junctions that mechanically integrate adjacent cells by coupling adhesive interactions mediated by desmosomal cadherins to the intermediate filament cytoskeletal network. Desmosomal cadherins are connected to intermediate filaments by densely clustered cytoplasmic plaque proteins comprising members of the armadillo gene family, including plakoglobin and plakophilins, and members of the plakin family of cytolinkers, such as desmoplakin. The importance of desmosomes in tissue integrity is highlighted by human diseases caused by mutations in desmosomal genes, autoantibody attack of desmosomal cadherins, and bacterial toxins that selectively target desmosomal cadherins. In addition to reviewing the well-known roles of desmosomal proteins in tissue integrity, this chapter also highlights the growing appreciation for how desmosomal proteins are integrated with cell signaling pathways to contribute to vertebrate tissue organization and differentiation.
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Affiliation(s)
- Andrew P Kowalczyk
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, USA
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36
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Abstract
Desmosomes are intercellular adhesive junctions that are particularly prominent in tissues experiencing mechanical stress, such as the heart and epidermis. Whereas the related adherens junction links actin to calcium-dependent adhesion molecules known as classical cadherins, desmosomes link intermediate filaments (IF) to the related subfamily of desmosomal cadherins. By tethering these stress-bearing cytoskeletal filaments to the plasma membrane, desmosomes serve as integrators of the IF cytoskeleton throughout a tissue. Recent evidence suggests that IF attachment in turn strengthens desmosomal adhesion. This collaborative arrangement results in formation of a supracellular network, which is critical for imparting mechanical integrity to tissues. Diseases and animal models targeting desmosomal components highlight the importance of desmosomes in development and tissue integrity, while the downregulation of individual protein components in cancer metastasis and wound healing suggests their importance in cell homeostasis. This chapter will provide an update on desmosome composition, function, and regulation, and will also discuss recent work which raises the possibility that desmosome proteins do more than play a structural role in tissues where they reside.
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37
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Munoz WA, Kloc M, Cho K, Lee M, Hofmann I, Sater A, Vleminckx K, McCrea PD. Plakophilin-3 is required for late embryonic amphibian development, exhibiting roles in ectodermal and neural tissues. PLoS One 2012; 7:e34342. [PMID: 22496792 PMCID: PMC3320641 DOI: 10.1371/journal.pone.0034342] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Accepted: 02/27/2012] [Indexed: 12/31/2022] Open
Abstract
The p120-catenin family has undergone a significant expansion during the evolution of vertebrates, resulting in varied functions that have yet to be discerned or fully characterized. Likewise, members of the plakophilins, a related catenin subfamily, are found throughout the cell with little known about their functions outside the desmosomal plaque. While the plakophilin-3 (Pkp3) knockout mouse resulted in skin defects, we find larger, including lethal effects following its depletion in Xenopus. Pkp3, unlike some other characterized catenins in amphibians, does not have significant maternal deposits of mRNA. However, during embryogenesis, two Pkp3 protein products whose temporal expression is partially complimentary become expressed. Only the smaller of these products is found in adult Xenopus tissues, with an expression pattern exhibiting distinctions as well as overlaps with those observed in mammalian studies. We determined that Xenopus Pkp3 depletion causes a skin fragility phenotype in keeping with the mouse knockout, but more novel, Xenopus tailbud embryos are hyposensitive to touch even in embryos lacking outward discernable phenotypes, and we additionally resolved disruptions in certain peripheral neural structures, altered establishment and migration of neural crest, and defects in ectodermal multiciliated cells. The use of two distinct morpholinos, as well as rescue approaches, indicated the specificity of these effects. Our results point to the requirement of Pkp3 in amphibian embryogenesis, with functional roles in a number of tissue types.
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Affiliation(s)
- William A. Munoz
- Department of Biochemistry and Molecular Biology, University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
- Program in Genes and Development, University of Texas Graduate School of Biomedical Science, Houston, Texas, United States of America
| | - Malgorzata Kloc
- Department of Biochemistry and Molecular Biology, University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
- Department of Surgery, The Methodist Hospital Research Institute, Houston, Texas, United States of America
| | - Kyucheol Cho
- Department of Biochemistry and Molecular Biology, University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
- Program in Genes and Development, University of Texas Graduate School of Biomedical Science, Houston, Texas, United States of America
| | - Moonsup Lee
- Department of Biochemistry and Molecular Biology, University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
- Program in Genes and Development, University of Texas Graduate School of Biomedical Science, Houston, Texas, United States of America
| | - Ilse Hofmann
- Joint Research Division Vascular Biology of the Medical Faculty Mannheim, University of Heidelberg- DKFZ, Mannheim, Germany
| | - Amy Sater
- Biology and Biochemistry Department, University of Houston, Houston, Texas, United States of America
| | - Kris Vleminckx
- Department for Molecular Biomedical Research, Flanders Institute for Biotechnology VIB, Ghent, Belgium
| | - Pierre D. McCrea
- Department of Biochemistry and Molecular Biology, University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
- Program in Genes and Development, University of Texas Graduate School of Biomedical Science, Houston, Texas, United States of America
- * E-mail:
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38
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Cabral RM, Tattersall D, Patel V, McPhail GD, Hatzimasoura E, Abrams DJ, South AP, Kelsell DP. The DSPII splice variant is crucial for desmosome-mediated adhesion in HaCaT keratinocytes. J Cell Sci 2012; 125:2853-61. [PMID: 22454510 DOI: 10.1242/jcs.084152] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Desmosomes are intercellular junctions specialised for strong adhesion that are prominent in the epidermis and heart muscle. Defective desmosomal function due to inherited mutations in the constitutive desmosomal gene desmoplakin (DSP) causes skin or heart disorders and in some instances both. Different mutations have different disease-causing molecular mechanisms as evidenced by the varying phenotypes resulting from mutations affecting different domains of the same protein, but the majority of these mechanisms remain to be determined. Here, we studied two mutations in DSP that lead to different dosages of the two major DSP splice variants, DSPI and DSPII, and compared their molecular mechanisms. One of the mutations results in total DSP haploinsufficiency and is associated with autosomal dominant striate palmoplantar keratoderma (PPK). The other leads to complete absence of DSPI and the minor isoform DSPIa but normal levels of DSPII, and is associated with autosomal recessive epidermolytic PPK, woolly hair and severe arrhythmogenic dilated cardiomyopathy. Using siRNA treatments to mimic these two mutations and additionally a DSPII-specific siRNA, we found striking differences between DSP isoforms with respect to keratinocyte adhesion upon cellular stress with DSPII being the key component in intermediate filament (IF) stability and desmosome-mediated adhesion. In addition, reduction in DSP expression reduced the amount of plakophilin 1, desmocollin (DSC) 2 and DSC3 with DSPI having a greater influence than DSPII on the expression levels of DSC3. These results suggest that the two major DSP splice variants are not completely redundant in function and that DSPII dosage is particularly important for desmosomal adhesion in the skin.
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Affiliation(s)
- Rita M Cabral
- Centre for Cutaneous Research, The Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, 4 Newark Street, London E1 2AT, UK
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39
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Brooke MA, Nitoiu D, Kelsell DP. Cell-cell connectivity: desmosomes and disease. J Pathol 2011; 226:158-71. [PMID: 21989576 DOI: 10.1002/path.3027] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Revised: 10/03/2011] [Accepted: 10/03/2011] [Indexed: 01/12/2023]
Abstract
Cell-cell connectivity is an absolute requirement for the correct functioning of cells, tissues and entire organisms. At the level of the individual cell, direct cell-cell adherence and communication is mediated by the intercellular junction complexes: desmosomes, adherens, tight and gap junctions. A broad spectrum of inherited, infectious and auto-immune diseases can affect the proper function of intercellular junctions and result in either diseases affecting specific individual tissues or widespread syndromic conditions. A particularly diverse group of diseases result from direct or indirect disruption of desmosomes--a consequence of their importance in tissue integrity, their extensive distribution, complex structure, and the wide variety of functions their components accomplish. As a consequence, disruption of desmosomal assembly, structure or integrity disrupts not only their intercellular adhesive function but also their functions in cell communication and regulation, leading to such diverse pathologies as cardiomyopathy, epidermal and mucosal blistering, palmoplantar keratoderma, woolly hair, keratosis, epidermolysis bullosa, ectodermal dysplasia and alopecia. Here, as well as describing the importance of the other intercellular junctions, we focus primarily on the desmosome, its structure and its role in disease. We will examine the various pathologies that result from impairment of desmosome function and thereby demonstrate the importance of desmosomes to tissues and to the organism as a whole.
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Affiliation(s)
- Matthew A Brooke
- Centre for Cutaneous Research, Blizard Institute, Barts and the London School of Medicine and Dentistry, London, UK
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40
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Crystal structure of a rigid four-spectrin-repeat fragment of the human desmoplakin plakin domain. J Mol Biol 2011; 409:800-12. [PMID: 21536047 DOI: 10.1016/j.jmb.2011.04.046] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 04/14/2011] [Accepted: 04/16/2011] [Indexed: 12/17/2022]
Abstract
The plakin protein family serves to connect cell-cell and cell-matrix adhesion molecules to the intermediate filament cytoskeleton. Desmoplakin (DP) is an integral part of desmosomes, where it links desmosomal cadherins to the intermediate filaments. The 1056-amino-acid N-terminal region of DP contains a plakin domain common to members of the plakin family. Plakin domains contain multiple copies of spectrin repeats (SRs). We determined the crystal structure of a fragment of DP, residues 175-630, consisting of four SRs and an inserted SH3 domain. The four repeats form an elongated, rigid structure. The SH3 domain is present in a loop between two helices of an SR and interacts extensively with the preceding SR in a manner that appears to limit inter-repeat flexibility. The intimate intramolecular association of the SH3 domain with the preceding SR is also observed in plectin, another plakin protein, but not in α-spectrin, suggesting that the SH3 domain of plakins contributes to the stability and rigidity of this subfamily of SR-containing proteins.
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41
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Demirag GG, Sullu Y, Gurgenyatagi D, Okumus NO, Yucel I. Expression of plakophilins (PKP1, PKP2, and PKP3) in gastric cancers. Diagn Pathol 2011; 6:1. [PMID: 21194493 PMCID: PMC3025932 DOI: 10.1186/1746-1596-6-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2010] [Accepted: 01/02/2011] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND The importance of cell-cell junction proteins (including armadillo proteins) in tumor biology is known, but limited with regard to plakophilins. We explored the relationship between plakophilins (PKP1, PKP2, PKP3) to gastric cancer via immunohistochemical techniques. METHODS We compared the immunohistochemistry of PKPs in 34 gastric adenocarcinomas and 20 normal gastric tissues. RESULTS In gastric cancer, PKP1 expression was unchanged but PKP2 and PKP3 were significantly decreased as compared to normal controls. There was no observable clinical association with PKP1 or PKP2 expression; however, low PKP3 level and poor prognosis appeared to correlate with regards to node number and tumor stage. The mean disease-free survival (DFS) was 38 ± 3 months (range: 32 - 44) and mean overall survival (OS) 42 ± 4 months (range: 38 - 50). Decreased PKP2 appeared to negatively impact DFS. CONCLUSION Decreased PKP2 and PKP3 may be early prognostic markers and loss of PKP3 expression during gastric carcinoma progression may indicate an invasive phenotype.
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Affiliation(s)
- Guzin G Demirag
- Ondokuz Mayis University, Faculty of Medicine, Department of Pathology, Samsun, Turkey
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42
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Lie PPY, Cheng CY, Mruk DD. The biology of the desmosome-like junction a versatile anchoring junction and signal transducer in the seminiferous epithelium. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2011; 286:223-69. [PMID: 21199783 PMCID: PMC4381909 DOI: 10.1016/b978-0-12-385859-7.00005-7] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Mammalian spermatogenesis, a complex process that involves the movement of developing germ cells across the seminiferous epithelium, entails extensive restructuring of Sertoli-Sertoli and Sertoli-germ cell junctions. Presently, it is not entirely clear how zygotene spermatocytes gain entry into the adluminal compartment of the seminiferous epithelium, which is sealed off from the systemic circulation by the Sertoli cell component of the blood-testis barrier, without compromising barrier integrity. To begin to address this question, it is critical that we first have a good understanding of the biology and the regulation of different types of Sertoli-Sertoli and Sertoli-germ cell junctions in the testis. Supported by recent studies in the field, we discuss how crosstalk between different types of junctions contributes to their restructuring during germ cell movement across the blood-testis barrier. We place special emphasis on the emerging role of desmosome-like junctions as signal transducers during germ cell movement across the seminiferous epithelium.
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Affiliation(s)
- Pearl P Y Lie
- Population Council, Center for Biomedical Research, New York, New York, USA
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43
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The molecular evolution of the p120-catenin subfamily and its functional associations. PLoS One 2010; 5:e15747. [PMID: 21209830 PMCID: PMC3013132 DOI: 10.1371/journal.pone.0015747] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Accepted: 11/26/2010] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND p120-catenin (p120) is the prototypical member of a subclass of armadillo-related proteins that includes δ-catenin/NPRAP, ARVCF, p0071, and the more distantly related plakophilins 1-3. In vertebrates, p120 is essential in regulating surface expression and stability of all classical cadherins, and directly interacts with Kaiso, a BTB/ZF family transcription factor. METHODOLOGY/PRINCIPAL FINDINGS To clarify functional relationships between these proteins and how they relate to the classical cadherins, we have examined the proteomes of 14 diverse vertebrate and metazoan species. The data reveal a single ancient δ-catenin-like p120 family member present in the earliest metazoans and conserved throughout metazoan evolution. This single p120 family protein is present in all protostomes, and in certain early-branching chordate lineages. Phylogenetic analyses suggest that gene duplication and functional diversification into "p120-like" and "δ-catenin-like" proteins occurred in the urochordate-vertebrate ancestor. Additional gene duplications during early vertebrate evolution gave rise to the seven vertebrate p120 family members. Kaiso family members (i.e., Kaiso, ZBTB38 and ZBTB4) are found only in vertebrates, their origin following that of the p120-like gene lineage and coinciding with the evolution of vertebrate-specific mechanisms of epigenetic gene regulation by CpG island methylation. CONCLUSIONS/SIGNIFICANCE The p120 protein family evolved from a common δ-catenin-like ancestor present in all metazoans. Through several rounds of gene duplication and diversification, however, p120 evolved in vertebrates into an essential, ubiquitously expressed protein, whereas loss of the more selectively expressed δ-catenin, p0071 and ARVCF are tolerated in most species. Together with phylogenetic studies of the vertebrate cadherins, our data suggest that the p120-like and δ-catenin-like genes co-evolved separately with non-neural (E- and P-cadherin) and neural (N- and R-cadherin) cadherin lineages, respectively. The expansion of p120 relative to δ-catenin during vertebrate evolution may reflect the pivotal and largely disproportionate role of the non-neural cadherins with respect to evolution of the wide range of somatic morphology present in vertebrates today.
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44
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Hatzfeld M. A nuclear function for plakophilin-1 in the DNA damage response? J Invest Dermatol 2010; 130:2538-40. [PMID: 20944636 DOI: 10.1038/jid.2010.258] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Plakophilins are proteins of the desmosomal plaque. Based on the observation that plakophilins localize not only to desmosomes but also to the cytoplasm and nucleus, additional functions in cell signaling have been proposed. In this issue, Sobolik-Delmaire et al. address the nuclear function of Plakophilin-1. The authors show that Plakophilin-1 interacts with ssDNA in vitro and may have a function in protecting cells from DNA damage.
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45
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Beaudry VG, Jiang D, Dusek RL, Park EJ, Knezevich S, Ridd K, Vogel H, Bastian BC, Attardi LD. Loss of the p53/p63 regulated desmosomal protein Perp promotes tumorigenesis. PLoS Genet 2010; 6:e1001168. [PMID: 20975948 PMCID: PMC2958815 DOI: 10.1371/journal.pgen.1001168] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Accepted: 09/20/2010] [Indexed: 01/01/2023] Open
Abstract
Dysregulated cell–cell adhesion plays a critical role in epithelial cancer development. Studies of human and mouse cancers have indicated that loss of adhesion complexes known as adherens junctions contributes to tumor progression and metastasis. In contrast, little is known regarding the role of the related cell–cell adhesion junction, the desmosome, during cancer development. Studies analyzing expression of desmosome components during human cancer progression have yielded conflicting results, and therefore genetic studies using knockout mice to examine the functional consequence of desmosome inactivation for tumorigenesis are essential for elucidating the role of desmosomes in cancer development. Here, we investigate the consequences of desmosome loss for carcinogenesis by analyzing conditional knockout mice lacking Perp, a p53/p63 regulated gene that encodes an important component of desmosomes. Analysis of Perp-deficient mice in a UVB-induced squamous cell skin carcinoma model reveals that Perp ablation promotes both tumor initiation and progression. Tumor development is associated with inactivation of both of Perp's known functions, in apoptosis and cell–cell adhesion. Interestingly, Perp-deficient tumors exhibit widespread downregulation of desmosomal constituents while adherens junctions remain intact, suggesting that desmosome loss is a specific event important for tumorigenesis rather than a reflection of a general change in differentiation status. Similarly, human squamous cell carcinomas display loss of PERP expression with retention of adherens junctions components, indicating that this is a relevant stage of human cancer development. Using gene expression profiling, we show further that Perp loss induces a set of inflammation-related genes that could stimulate tumorigenesis. Together, these studies suggest that Perp-deficiency promotes cancer by enhancing cell survival, desmosome loss, and inflammation, and they highlight a fundamental role for Perp and desmosomes in tumor suppression. An understanding of the factors affecting cancer progression is important for ultimately improving the diagnosis, prognostication, and treatment of cancer. Changes in tissue architecture, such as loss of adhesion between cells, have been shown to facilitate cancer development, especially metastasis where cells can detach from a tumor and spread throughout the body. While various studies have demonstrated that inactivation of an adhesion complex known as the adherens junction promotes cancer development and metastasis, little is known about the role of the desmosome—a related cell–cell adhesion complex—in tumorigenesis. Here we examine the consequence of desmosome-deficiency for tumor development by studying mice lacking a key component of desmosomes in the skin, a protein known as Perp. Using a mouse model for human skin cancer, in which ultraviolet light promotes skin cancer development, we demonstrate that Perp-deficiency indeed leads to accelerated skin tumorigenesis. We similarly observe that PERP is lost during human skin cancer development, suggesting that PERP is also important as a tumor suppressor in humans. These findings demonstrate that desmosome-deficiency achieved by Perp inactivation can promote cancer and suggest the potential utility of monitoring PERP status for staging, prognostication, or treatment of human cancers.
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Affiliation(s)
- Veronica G. Beaudry
- Department of Radiation Oncology, Division of Radiation and Cancer Biology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Dadi Jiang
- Department of Radiation Oncology, Division of Radiation and Cancer Biology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Rachel L. Dusek
- Department of Radiation Oncology, Division of Radiation and Cancer Biology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Eunice J. Park
- Department of Radiation Oncology, Division of Radiation and Cancer Biology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Stevan Knezevich
- Department of Pathology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Katie Ridd
- Department of Dermatology, University of California San Francisco, San Francisco, California, United States of America
| | - Hannes Vogel
- Department of Pathology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Boris C. Bastian
- Department of Dermatology, University of California San Francisco, San Francisco, California, United States of America
- Department of Pathology and UCSF Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, California, United States of America
| | - Laura D. Attardi
- Department of Radiation Oncology, Division of Radiation and Cancer Biology, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Genetics, Stanford University School of Medicine, Stanford, California, United States of America
- * E-mail:
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Abstract
Desmosomes are intercellular junctions that tether intermediate filaments to the plasma membrane. Desmogleins and desmocollins, members of the cadherin superfamily, mediate adhesion at desmosomes. Cytoplasmic components of the desmosome associate with the desmosomal cadherin tails through a series of protein interactions, which serve to recruit intermediate filaments to sites of desmosome assembly. These desmosomal plaque components include plakoglobin and the plakophilins, members of the armadillo gene family. Linkage to the cytoskeleton is mediated by the intermediate filament binding protein, desmoplakin, which associates with both plakoglobin and plakophilins. Although desmosomes are critical for maintaining stable cell-cell adhesion, emerging evidence indicates that they are also dynamic structures that contribute to cellular processes beyond that of cell adhesion. This article outlines the structure and function of the major desmosomal proteins, and explores the contributions of this protein complex to tissue architecture and morphogenesis.
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Affiliation(s)
- Emmanuella Delva
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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47
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Abstract
Desmosomes are intercellular junctions whose primary function is strong intercellular adhesion, known as hyperadhesion. In the present review, we discuss how their structure appears to support this function as well as how they are assembled and down-regulated. Desmosomal components also have signalling functions that are important in tissue development and remodelling. Their adhesive and signalling functions are both compromised in genetic and autoimmune diseases that affect the heart, skin and mucous membranes. We conclude that much work is required on structure–function relationships within desmosomes in vivo and on how they participate in signalling processes to enhance our knowledge of tissue homoeostasis and human disease.
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48
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Sobolik-Delmaire T, Reddy R, Pashaj A, Roberts BJ, Wahl JK. Plakophilin-1 localizes to the nucleus and interacts with single-stranded DNA. J Invest Dermatol 2010; 130:2638-46. [PMID: 20613778 DOI: 10.1038/jid.2010.191] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Plakophilins (Pkp-1, -2, and -3) comprise a family of armadillo repeat-containing proteins first identified as desmosomal plaque components, in which they link desmoplakin to the desmosomal cadherins. In addition to their role in desmosomal cell-cell adhesion, Pkps also localize to the nucleus, where they perform unknown functions. Of the three Pkps, Pkp-1 is most readily detected in the nucleus, where it is localized to the nucleoplasm. Pkp chimeras containing the Pkp-1 head domain and Pkp-3 armadillo repeat domain were localized to the nucleus in A431 cells, whereas Pkp chimeras containing the Pkp-3 head domain and Pkp-1 armadillo repeat domain localized to the desmosome and the cytosol. DNAse I digestion of chromatin in cultured cells results in loss of nuclear Pkp-1, suggesting that Pkp-1 associates specifically with nuclear components. In addition, in vitro assays revealed that the amino-terminal head domains of Pkps-1 and -2 were sufficient to bind single-stranded DNA. Induction of DNA damage induced a partial redistribution of Pkp-1 protein to the nucleolus, and depletion of Pkp-1 resulted in increased survival in response to DNA damage. These data suggest that in addition to mediating desmosome assembly, the nuclear pool of Pkp can influence cell survival by interactions with DNA.
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Affiliation(s)
- Tammy Sobolik-Delmaire
- Department of Oral Biology, UNMC College of Dentistry, University of Nebraska Medical Center, Lincoln, Nebraska 68583-0740, USA
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Cabral RM, Wan H, Cole CL, Abrams DJ, Kelsell DP, South AP. Identification and characterization of DSPIa, a novel isoform of human desmoplakin. Cell Tissue Res 2010; 341:121-9. [PMID: 20524011 PMCID: PMC2896628 DOI: 10.1007/s00441-010-0989-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Accepted: 04/27/2010] [Indexed: 11/21/2022]
Abstract
Desmoplakin is a ubiquitous component of desmosomes and desmosome-like structures, such as the cardiomyocyte area composita. Two major isoforms, desmoplakin I (DSPI) and desmoplakin II (DSPII) are encoded by alternative mRNA transcripts differentially spliced from the same gene. The resulting proteins are identical in amino acid sequence with the exception that DSPII contains only one third of the central alpha-helical rod domain present in DSPI. Here we describe a novel minor isoform of desmoplakin that is also produced by alternative splicing of the desmoplakin gene and that we name desmoplakin Ia (DSPIa). DSPIa is an alternatively spliced DSPI mRNA with a unique splice donor site that is 90% homologous to and downstream of the DSPII specific donor. The resulting DSPIa mRNA is in-frame and encodes a protein that has a central alpha-helical rod domain of intermediate size and that is 156 amino acids larger than DSPII and 443 amino acids smaller than DSPI. We demonstrate, through recombinant expression and short interfering RNA knockdown, that the DSPIa protein is readily detectable, albeit at substantially lower levels than the dominant isoforms, DSPI and DSPII. DSPIa mRNA has a similar tissue distribution to that of DSPI and of DSPII.
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Affiliation(s)
- Rita M Cabral
- Centre for Cutaneous Research, Blizard Institute of Cell and Molecular Science, University of London, London, UK
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50
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Ordered assembly of the adhesive and electrochemical connections within newly formed intercalated disks in primary cultures of adult rat cardiomyocytes. J Biomed Biotechnol 2010; 2010:624719. [PMID: 20467587 PMCID: PMC2868981 DOI: 10.1155/2010/624719] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2009] [Accepted: 02/17/2010] [Indexed: 02/06/2023] Open
Abstract
The intercalated disk (ID) is a complex structure that electromechanically couples adjoining cardiac myocytes into a functional syncitium. The integrity of the disk is essential for normal cardiac function, but how the diverse elements are assembled into a fully integrated structure is not well understood. In this study, we examined the assembly of new IDs in primary cultures of adult rat cardiac myocytes. From 2 to 5 days after dissociation, the cells flatten and spread, establishing new cell-cell contacts in a manner that recapitulates the in vivo processes that occur during heart development and myocardial remodeling. As cells make contact with their neighbors, transmembrane adhesion proteins localize along the line of apposition, concentrating at the sites of membrane attachment of the terminal sarcomeres. Cx43 gap junctions and ankyrin-G, an essential cytoskeletal component of voltage gated sodium channel complexes, were secondarily recruited to membrane domains involved in cell-cell contacts. The consistent order of the assembly process suggests that there are specific scaffolding requirements for integration of the mechanical and electrochemical elements of the disk. Defining the relationships that are the foundation of disk assembly has important implications for understanding the mechanical dysfunction and cardiac arrhythmias that accompany alterations of ID architecture.
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