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Transcriptional Analysis of the Endostyle Reveals Pharyngeal Organ Functions in Ascidian. BIOLOGY 2023; 12:biology12020245. [PMID: 36829522 PMCID: PMC9953650 DOI: 10.3390/biology12020245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 01/30/2023] [Accepted: 02/02/2023] [Indexed: 02/09/2023]
Abstract
The endostyle is a pharyngeal organ with an opening groove and cilia in invertebrate chordates (amphioxus and ascidian) and cyclostomate (lamprey), serving as a filter-feeding tract and thyroid-secreting location. Emerging evidence implies its complex cellular composition and potentially versatile functions. Multiple cell types in the endostyle have been thought to be progenitors of complex organs in advanced vertebrates. To describe the expression profile and the potential functions, bulk RNA sequencing on the endostyle in ascidian Styela clava was conducted and distinct markers were selected by multileveled comparative analysis. Transcriptional data assay and qRT-PCR-verified results showed the regional expression patterns of Hox genes in the longitudinal axis. Organ-specific markers of the endostyle was proposed by comparing expression with the main organs of the ascidian. A cross-species transcriptional profile projection between the endostyle and organs from Danio rerio and Homo sapiens indicates a robust homogenous relationship to the thyroid and digestive system of the endostyle. The high similarity between the endostyle and the head kidney in zebrafish/the bone marrow in human implies uniquely profound functions of the pharyngeal organ in proto-vertebrates. Our result revealed that the transcriptional profile of the human parathyroid gland was similar to the ascidian endostyle, indicating the evolutionary origin of vertebrate hormone secretion organs.
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Kaplan L, Drexler C, Pfaller AM, Brenna S, Wunderlich KA, Dimitracopoulos A, Merl-Pham J, Perez MT, Schlötzer-Schrehardt U, Enzmann V, Samardzija M, Puig B, Fuchs P, Franze K, Hauck SM, Grosche A. Retinal regions shape human and murine Müller cell proteome profile and functionality. Glia 2023; 71:391-414. [PMID: 36334068 DOI: 10.1002/glia.24283] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Revised: 09/29/2022] [Accepted: 10/07/2022] [Indexed: 11/08/2022]
Abstract
The human macula is a highly specialized retinal region with pit-like morphology and rich in cones. How Müller cells, the principal glial cell type in the retina, are adapted to this environment is still poorly understood. We compared proteomic data from cone- and rod-rich retinae from human and mice and identified different expression profiles of cone- and rod-associated Müller cells that converged on pathways representing extracellular matrix and cell adhesion. In particular, epiplakin (EPPK1), which is thought to play a role in intermediate filament organization, was highly expressed in macular Müller cells. Furthermore, EPPK1 knockout in a human Müller cell-derived cell line led to a decrease in traction forces as well as to changes in cell size, shape, and filopodia characteristics. We here identified EPPK1 as a central molecular player in the region-specific architecture of the human retina, which likely enables specific functions under the immense mechanical loads in vivo.
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Affiliation(s)
- Lew Kaplan
- Department of Physiological Genomics, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Corinne Drexler
- Max Perutz Labs, Department of Biochemistry and Cell Biology, University of Vienna, Vienna Biocenter Campus (VBC), Vienna, Austria.,Vienna Biocenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, Vienna, Austria
| | - Anna M Pfaller
- Department of Physiological Genomics, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Santra Brenna
- Neurology Department, Experimental Research in Stroke and Inflammation (ERSI), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Kirsten A Wunderlich
- Department of Physiological Genomics, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Andrea Dimitracopoulos
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - Juliane Merl-Pham
- Research Unit Protein Science and Metabolomics and Proteomics Core, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Maria-Theresa Perez
- Department of Clinical Sciences, Division of Ophthalmology, Lund University, Lund, Sweden.,NanoLund, Nanometer Structure Consortium, Lund University, Lund, Sweden
| | | | - Volker Enzmann
- Department of Ophthalmology, Bern University Hospital, Inselspital, University of Bern, Bern, Switzerland.,Department of BioMedical Research, University of Bern, Bern, Switzerland
| | - Marijana Samardzija
- Department of Ophthalmology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Berta Puig
- Neurology Department, Experimental Research in Stroke and Inflammation (ERSI), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Peter Fuchs
- Max Perutz Labs, Department of Biochemistry and Cell Biology, University of Vienna, Vienna Biocenter Campus (VBC), Vienna, Austria
| | - Kristian Franze
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK.,Institute of Medical Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.,Max-Planck-Zentrum für Physik und Medizin, Erlangen, Germany
| | - Stefanie M Hauck
- Research Unit Protein Science and Metabolomics and Proteomics Core, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Antje Grosche
- Department of Physiological Genomics, Ludwig-Maximilians-Universität München, Munich, Germany
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3
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Ratajczyk S, Drexler C, Windoffer R, Leube RE, Fuchs P. A Ca 2+-Mediated Switch of Epiplakin from a Diffuse to Keratin-Bound State Affects Keratin Dynamics. Cells 2022; 11:cells11193077. [PMID: 36231039 PMCID: PMC9563781 DOI: 10.3390/cells11193077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 09/19/2022] [Accepted: 09/23/2022] [Indexed: 11/16/2022] Open
Abstract
Keratins exert important structural but also cytoprotective functions. They have to be adaptable to support cellular homeostasis. Epiplakin (EPPK1) has been shown to decorate keratin filaments in epithelial cells and to play a protective role under stress, but the mechanism is still unclear. Using live-cell imaging of epithelial cells expressing fluorescently tagged EPPK1 and keratin, we report here an unexpected dynamic behavior of EPPK1 upon stress. EPPK1 was diffusely distributed throughout the cytoplasm and not associated with keratin filaments in living cells under standard culture conditions. However, ER-, oxidative and UV-stress, as well as cell fixation, induced a rapid association of EPPK1 with keratin filaments. This re-localization of EPPK1 was reversible and dependent on the elevation of cytoplasmic Ca2+ levels. Moreover, keratin filament association of EPPK1 led to significantly reduced keratin dynamics. Thus, we propose that EPPK1 stabilizes the keratin network in stress conditions, which involve increased cytoplasmic Ca2+.
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Affiliation(s)
- Sonia Ratajczyk
- Max Perutz Labs, Department of Biochemistry and Cell Biology, University of Vienna, Vienna Biocenter Campus (VBC), A-1030 Vienna, Austria
- Vienna Biocenter PhD Program, A Doctoral School of the University of Vienna and Medical University of Vienna, A-1030 Vienna, Austria
| | - Corinne Drexler
- Max Perutz Labs, Department of Biochemistry and Cell Biology, University of Vienna, Vienna Biocenter Campus (VBC), A-1030 Vienna, Austria
- Vienna Biocenter PhD Program, A Doctoral School of the University of Vienna and Medical University of Vienna, A-1030 Vienna, Austria
| | - 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
| | - Peter Fuchs
- Max Perutz Labs, Department of Biochemistry and Cell Biology, University of Vienna, Vienna Biocenter Campus (VBC), A-1030 Vienna, Austria
- Correspondence: ; Tel.: +43-1-4277-52855
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Serum Epiplakin Might Be a Potential Serodiagnostic Biomarker for Bladder Cancer. Cancers (Basel) 2021; 13:cancers13205150. [PMID: 34680299 PMCID: PMC8534213 DOI: 10.3390/cancers13205150] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Revised: 10/08/2021] [Accepted: 10/09/2021] [Indexed: 11/16/2022] Open
Abstract
Tumor markers that can be detected at an early stage are needed. Here, we evaluated the epiplakin expression levels in sera from patients with bladder cancer (BC). Using a micro-dot blot array, we evaluated epiplakin expression levels in 60 patients with BC, 20 patients with stone disease, and 28 healthy volunteers. The area under the curve (AUC) and best cut-off point were calculated using receiver-operating characteristic (ROC) analysis. Serum epiplakin levels were significantly higher in patients with BC than in those with stone disease (p = 0.0013) and in healthy volunteers (p < 0.0001). The AUC-ROC level for BC was 0.78 (95% confidence interval (CI) = 0.69-0.87). Using a cut-off point of 873, epiplakin expression levels exhibited 68.3% sensitivity and 79.2% specificity for BC. However, the serum epiplakin levels did not significantly differ by sex, age, pathological stage and grade, or urine cytology. We performed immunohistochemical staining using the same antibody on another cohort of 127 patients who underwent radical cystectomy. Univariate and multivariate analysis results showed no significant differences between epiplakin expression, clinicopathological findings, and patient prognoses. Our results showed that serum epiplakin might be a potential serodiagnostic biomarker in patients with BC.
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Ueo D, Furuhashi M, Sasaki T, Kudoh J, Parry DAD, Winter DJ, Sasaki T, Hashimoto T, Tsuruta D, Fujiwara S. Intragenic copy number variation in mouse epiplakin 1 (Eppk1) and the conservation of the repeat structures in the lower vertebrates. J Dermatol Sci 2021; 103:186-189. [PMID: 34275721 DOI: 10.1016/j.jdermsci.2021.07.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Revised: 07/03/2021] [Accepted: 07/06/2021] [Indexed: 10/20/2022]
Affiliation(s)
- Daisuke Ueo
- Department of Dermatology, Faculty of Medicine, Oita University, Oita, Japan
| | - Mie Furuhashi
- Laboratory of Gene Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Takashi Sasaki
- Center for Supercentenarian Medical Research, Keio University School of Medicine, Tokyo, Japan
| | - Jun Kudoh
- Laboratory of Gene Medicine, Keio University School of Medicine, Tokyo, Japan
| | - David A D Parry
- Department of Biophysics, School of Fundamental Sciences, Massey University, Palmerston North, New Zealand
| | - David J Winter
- Department of Computational Genomics, School of Fundamental Sciences, Massey University, Palmerston North, New Zealand
| | - Takako Sasaki
- Department of Matrix Biology, Faculty of Medicine, Oita University, Oita, Japan
| | - Takashi Hashimoto
- Department of Dermatology, Osaka City University Graduate School of Medicine, Osaka, Japan
| | - Daisuke Tsuruta
- Department of Dermatology, Osaka City University Graduate School of Medicine, Osaka, Japan
| | - Sakuhei Fujiwara
- Department of Dermatology, Faculty of Medicine, Oita University, Oita, Japan; Department of Dermatology, Osaka City University Graduate School of Medicine, Osaka, Japan.
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Mohammed F, Trieber C, Overduin M, Chidgey M. Molecular mechanism of intermediate filament recognition by plakin proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118801. [PMID: 32712070 DOI: 10.1016/j.bbamcr.2020.118801] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 07/15/2020] [Accepted: 07/20/2020] [Indexed: 12/26/2022]
Abstract
The plakin family of cytolinkers interacts with intermediate filaments (IFs) through plakin repeat domain (PRD) and linker modules. Recent structure/function studies have established the molecular basis of envoplakin-PRD and periplakin-linker interactions with vimentin. Both plakin modules share a broad basic groove which recognizes acidic rod elements on IFs, a mechanism that is applicable to other plakin family members. This review postulates a universal IF engagement mechanism that illuminates the specific effects of pathogenic mutations associated with diseases including arrhythmogenic right ventricular cardiomyopathy, and reveals how diverse plakin proteins offer tailored IF tethering to ensure stable, dynamic and regulated cellular structures.
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Affiliation(s)
- Fiyaz Mohammed
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham B15 2TT, UK.
| | - Catharine Trieber
- Department of Biochemistry, Faculty of Medicine and Dentistry, 474 Medical Sciences Building, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
| | - Michael Overduin
- Department of Biochemistry, Faculty of Medicine and Dentistry, 474 Medical Sciences Building, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
| | - Martyn Chidgey
- Institute of Clinical Sciences, University of Birmingham, Birmingham B15 2TT, UK.
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Khaled ML, Bykhovskaya Y, Yablonski SER, Li H, Drewry MD, Aboobakar IF, Estes A, Gao XR, Stamer WD, Xu H, Allingham RR, Hauser MA, Rabinowitz YS, Liu Y. Differential Expression of Coding and Long Noncoding RNAs in Keratoconus-Affected Corneas. Invest Ophthalmol Vis Sci 2018; 59:2717-2728. [PMID: 29860458 PMCID: PMC5984031 DOI: 10.1167/iovs.18-24267] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 04/23/2018] [Indexed: 12/22/2022] Open
Abstract
Purpose Keratoconus (KC) is the most common corneal ectasia. We aimed to determine the differential expression of coding and long noncoding RNAs (lncRNAs) in human corneas affected with KC. Methods From the corneas of 10 KC patients and 8 non-KC healthy controls, 200 ng total RNA was used to prepare sequencing libraries with the SMARTer Stranded RNA-Seq kit after ribosomal RNA depletion, followed by paired-end 50-bp sequencing with Illumina Sequencer. Differential analysis was done using TopHat/Cufflinks with a gene file from Ensembl and a lncRNA file from NONCODE. Pathway analysis was performed using WebGestalt. Using the expression level of differentially expressed coding and noncoding RNAs in each sample, we correlated their expression levels in KC and controls separately and identified significantly different correlations in KC against controls followed by visualization using Cytoscape. Results Using |fold change| ≥ 2 and a false discovery rate ≤ 0.05, we identified 436 coding RNAs and 584 lncRNAs with differential expression in the KC-affected corneas. Pathway analysis indicated the enrichment of genes involved in extracellular matrix, protein binding, glycosaminoglycan binding, and cell migration. Our correlation analysis identified 296 pairs of significant KC-specific correlations containing 117 coding genes enriched in functions related to cell migration/motility, extracellular space, cytokine response, and cell adhesion. Our study highlighted the potential roles of several genes (CTGF, SFRP1, AQP5, lnc-WNT4-2:1, and lnc-ALDH3A2-2:1) and pathways (TGF-β, WNT signaling, and PI3K/AKT pathways) in KC pathogenesis. Conclusions Our RNA-Seq-based differential expression and correlation analyses have identified many potential KC contributing coding and noncoding RNAs.
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Affiliation(s)
- Mariam Lofty Khaled
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, Georgia, United States
| | - Yelena Bykhovskaya
- Regenerative Medicine Institute and Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, California, United States
| | - Sarah E. R. Yablonski
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, Georgia, United States
- STAR Program, Augusta University, Augusta, Georgia, United States
| | - Hanzhou Li
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, Georgia, United States
| | - Michelle D. Drewry
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, Georgia, United States
| | - Inas F. Aboobakar
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina, United States
| | - Amy Estes
- Department of Ophthalmology, Augusta University, Augusta, Georgia, United States
| | - X. Raymond Gao
- Department of Ophthalmology and Visual Science, University of Illinois at Chicago, Chicago, Illinois, United States
| | - W. Daniel Stamer
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina, United States
| | - Hongyan Xu
- Department of Population Health Sciences, Augusta University, Augusta, Georgia, United States
| | - R. Rand Allingham
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina, United States
| | - Michael A. Hauser
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina, United States
- Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States
| | - Yaron S. Rabinowitz
- Regenerative Medicine Institute and Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, California, United States
| | - Yutao Liu
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, Georgia, United States
- James and Jean Culver Vision Discovery Institute, Medical College of Georgia, Augusta University, Augusta, Georgia, United States
- Center for Biotechnology and Genomic Medicine, Augusta University, Augusta, Georgia, United States
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Mechanism of intermediate filament recognition by plakin repeat domains revealed by envoplakin targeting of vimentin. Nat Commun 2016; 7:10827. [PMID: 26935805 PMCID: PMC4782060 DOI: 10.1038/ncomms10827] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 01/23/2016] [Indexed: 01/14/2023] Open
Abstract
Plakin proteins form critical connections between cell junctions and the cytoskeleton; their disruption within epithelial and cardiac muscle cells cause skin-blistering diseases and cardiomyopathies. Envoplakin has a single plakin repeat domain (PRD) which recognizes intermediate filaments through an unresolved mechanism. Herein we report the crystal structure of envoplakin's complete PRD fold, revealing binding determinants within its electropositive binding groove. Four of its five internal repeats recognize negatively charged patches within vimentin via five basic determinants that are identified by nuclear magnetic resonance spectroscopy. Mutations of the Lys1901 or Arg1914 binding determinants delocalize heterodimeric envoplakin from intracellular vimentin and keratin filaments in cultured cells. Recognition of vimentin is abolished when its residues Asp112 or Asp119 are mutated. The latter slot intermediate filament rods into basic PRD domain grooves through electrosteric complementarity in a widely applicable mechanism. Together this reveals how plakin family members form dynamic linkages with cytoskeletal frameworks. Plakin proteins link cell junctions to cytoskeletal frameworks, and their disruption within epithelial and cardiac muscle cells cause skin blistering diseases and cardiomyopathies. Here the authors use structural biology approaches to reveal the mechanism that allows plakins to recognize intermediate filaments within the cytoskeleton.
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Epiplakin Is a Paraneoplastic Pemphigus Autoantigen and Related to Bronchiolitis Obliterans in Japanese Patients. J Invest Dermatol 2016; 136:399-408. [DOI: 10.1038/jid.2015.408] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 09/23/2015] [Accepted: 09/26/2015] [Indexed: 11/09/2022]
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Robert A, Hookway C, Gelfand VI. Intermediate filament dynamics: What we can see now and why it matters. Bioessays 2016; 38:232-43. [PMID: 26763143 DOI: 10.1002/bies.201500142] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The mechanical properties of vertebrate cells are largely defined by the system of intermediate filaments (IF). As part of a dense network, IF polymers are constantly rearranged and relocalized in the cell to fulfill their duty as cells change shape, migrate, or divide. With the development of new imaging technologies, such as photoconvertible proteins and super-resolution microscopy, a new appreciation for the complexity of IF dynamics has emerged. This review highlights new findings about the transport of IF, the remodeling of filaments by a process of severing and re-annealing, and the subunit exchange that occurs between filament precursors and a soluble pool of IF. We will also discuss the unique dynamic features of the keratin IF network. Finally, we will speculate about how the dynamic properties of IF are related to their functions.
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Affiliation(s)
- Amélie Robert
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Caroline Hookway
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Vladimir I Gelfand
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
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Szabo S, Wögenstein KL, Fuchs P. Functional and Genetic Analysis of Epiplakin in Epithelial Cells. Methods Enzymol 2015; 569:261-85. [PMID: 26778563 DOI: 10.1016/bs.mie.2015.06.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Epiplakin is a large member (>700 kDa) of the plakin protein family and exclusively expressed in epithelial cell types. Compared to other plakin proteins epiplakin exhibits an unusual structure as it consists entirely of a variable number of consecutive plakin repeat domains (13 in humans, 16 in mice). The only binding partners of epiplakin identified so far are keratins of simple as well as of stratified epithelia. Epiplakin-deficient mice show no obvious spontaneous phenotype. However, ex vivo studies using epiplakin-deficient primary cells indicated protective functions of epiplakin in response to stress. Recent studies using stress models for organs of the gastrointestinal tract revealed that epiplakin-deficient mice develop more pronounced pancreas and liver injuries than their wild-type littermates. In addition, impaired stress-induced keratin network reorganization was observed in the affected organs, and primary epiplakin-deficient hepatocytes showed reduced tolerance for forced keratin overexpression which could be rescued by a chemical chaperone. These findings indicate protective functions of epiplakin in chaperoning disease-induced keratin reorganization. In this review, we describe some of the methods we used to analyze epiplakin's function with the focus on biochemical and ex vivo techniques.
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Affiliation(s)
- Sandra Szabo
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Vienna Biocenter (VBC), Vienna, Austria
| | - Karl L Wögenstein
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Vienna Biocenter (VBC), Vienna, Austria
| | - Peter Fuchs
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Vienna Biocenter (VBC), Vienna, Austria.
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Development of a Novel Green Fluorescent Protein-Based Binding Assay to Study the Association of Plakins with Intermediate Filament Proteins. Methods Enzymol 2015; 569:117-37. [PMID: 26778556 DOI: 10.1016/bs.mie.2015.06.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Protein-protein interactions are fundamental for most biological processes, such as the formation of cellular structures and enzymatic complexes or in signaling pathways. The identification and characterization of protein-protein interactions are therefore essential for understanding the mechanisms and regulation of biological systems. The organization and dynamics of the cytoskeleton, as well as its anchorage to specific sites in the plasma membrane and organelles, are regulated by the plakins. These structurally related proteins anchor different cytoskeletal networks to each other and/or to other cellular structures. The association of several plakins with intermediate filaments (IFs) is critical for maintenance of the cytoarchitecture. Pathogenic mutations in the genes encoding different plakins can lead to dramatic manifestations, occurring principally in the skin, striated muscle, and/or nervous system, due to cytoskeletal disorganization resulting in abnormal cell fragility. Nevertheless, it is still unclear how plakins bind to IFs, although some general rules are slowly emerging. We here describe in detail a recently developed protein-protein fluorescence binding assay, based on the production of recombinant proteins tagged with green fluorescent protein (GFP) and their use as fluid-phase fluorescent ligands on immobilized IF proteins. Using this method, we have been able to assess the ability of C-terminal regions of GFP-tagged plakin proteins to bind to distinct IF proteins and IF domains. This simple and sensitive technique, which is expected to facilitate further studies in this area, can also be potentially employed for any kind of protein-protein interaction studies.
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Szabo S, Wögenstein KL, Österreicher CH, Guldiken N, Chen Y, Doler C, Wiche G, Boor P, Haybaeck J, Strnad P, Fuchs P. Epiplakin attenuates experimental mouse liver injury by chaperoning keratin reorganization. J Hepatol 2015; 62:1357-66. [PMID: 25617501 PMCID: PMC4451473 DOI: 10.1016/j.jhep.2015.01.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 12/08/2014] [Accepted: 01/05/2015] [Indexed: 12/04/2022]
Abstract
BACKGROUND & AIMS Epiplakin is a member of the plakin protein family and exclusively expressed in epithelial tissues where it binds to keratins. Epiplakin-deficient (Eppk1(-/-)) mice displayed no obvious spontaneous phenotype, but their keratinocytes showed a faster keratin network breakdown in response to stress. The role of epiplakin in the stressed liver remained to be elucidated. METHODS Wild-type (WT) and Eppk1(-/-) mice were subjected to common bile duct ligation (CBDL) or fed with a 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-containing diet. The importance of epiplakin during keratin reorganization was assessed in primary hepatocytes. RESULTS Our experiments revealed that epiplakin is expressed in hepatocytes and cholangiocytes, and binds to keratin 8 (K8) and K18 via multiple domains. In several liver stress models epiplakin and K8 genes displayed identical expression patterns and transgenic K8 overexpression resulted in elevated hepatic epiplakin levels. After CBDL and DDC treatment, Eppk1(-/-) mice developed a more pronounced liver injury and their livers contained larger amounts of hepatocellular keratin granules, indicating impaired disease-induced keratin network reorganization. In line with these findings, primary Eppk1(-/-) hepatocytes showed increased formation of keratin aggregates after treatment with the phosphatase inhibitor okadaic acid, a phenotype which was rescued by the chemical chaperone trimethylamine N-oxide (TMAO). Finally, transfection experiments revealed that Eppk1(-/-) primary hepatocytes were less able to tolerate forced K8 overexpression and that TMAO treatment rescued this phenotype. CONCLUSION Our data indicate that epiplakin plays a protective role during experimental liver injuries by chaperoning disease-induced keratin reorganization.
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Affiliation(s)
- Sandra Szabo
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Karl L Wögenstein
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Christoph H Österreicher
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Nurdan Guldiken
- Department of Internal Medicine III and IZKF, University Hospital Aachen, Aachen, Germany
| | - Yu Chen
- Department of Internal Medicine III and IZKF, University Hospital Aachen, Aachen, Germany
| | - Carina Doler
- Institute of Pathology, Medical University of Graz, Graz, Austria
| | - Gerhard Wiche
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Peter Boor
- Division of Nephrology and Institute of Pathology, RWTH University of Aachen, Aachen, Germany
| | | | - Pavel Strnad
- Department of Internal Medicine III and IZKF, University Hospital Aachen, Aachen, Germany
| | - Peter Fuchs
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria.
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Wögenstein KL, Szabo S, Lunova M, Wiche G, Haybaeck J, Strnad P, Boor P, Wagner M, Fuchs P. Epiplakin deficiency aggravates murine caerulein-induced acute pancreatitis and favors the formation of acinar keratin granules. PLoS One 2014; 9:e108323. [PMID: 25232867 PMCID: PMC4169488 DOI: 10.1371/journal.pone.0108323] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 08/19/2014] [Indexed: 11/23/2022] Open
Abstract
Epiplakin, a member of the plakin protein family, is exclusively expressed in epithelial tissues and was shown to bind to keratins. Epiplakin-deficient (EPPK−/−) mice showed no obvious spontaneous phenotype, however, EPPK−/− keratinocytes displayed faster keratin network breakdown in response to stress. The role of epiplakin in pancreas, a tissue with abundant keratin expression, was not yet known. We analyzed epiplakin’s expression in healthy and inflamed pancreatic tissue and compared wild-type and EPPK−/− mice during caerulein-induced acute pancreatitis. We found that epiplakin was expressed primarily in ductal cells of the pancreas and colocalized with apicolateral keratin bundles in murine pancreatic acinar cells. Epiplakin’s diffuse subcellular localization in keratin filament-free acini of K8-deficient mice indicated that its filament-associated localization in acinar cells completely depends on its binding partner keratin. During acute pancreatitis, epiplakin was upregulated in acinar cells and its redistribution closely paralleled keratin reorganization. EPPK−/− mice suffered from aggravated pancreatitis but showed no obvious regeneration phenotype. At the most severe stage of the disease, EPPK−/− acinar cells displayed more keratin aggregates than those of wild-type mice. Our data propose epiplakin to be a protective protein during acute pancreatitis, and that its loss causes impaired disease-associated keratin reorganization.
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Affiliation(s)
- Karl L. Wögenstein
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Sandra Szabo
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Mariia Lunova
- Department of Internal Medicine III and IZKF, University Hospital Aachen, Aachen, Germany
| | - Gerhard Wiche
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | | | - Pavel Strnad
- Department of Internal Medicine III and IZKF, University Hospital Aachen, Aachen, Germany
| | - Peter Boor
- Division of Nephrology and Institute of Pathology, RWTH University of Aachen, Aachen, Germany
| | - Martin Wagner
- Department of Internal Medicine I, University Medical Center Ulm, Ulm, Germany
| | - Peter Fuchs
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
- * E-mail:
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15
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Shimada H, Nambu-Niibori A, Wilson-Morifuji M, Mizuguchi S, Araki N, Sumiyoshi H, Sato M, Mezaki Y, Senoo H, Ishikawa K, Hatano Y, Okamoto O, Fujiwara S. Epiplakin modifies the motility of the HeLa cells and accumulates at the outer surfaces of 3-D cell clusters. J Dermatol 2013; 40:249-58. [PMID: 23398049 DOI: 10.1111/1346-8138.12076] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Accepted: 11/21/2012] [Indexed: 11/27/2022]
Abstract
Elimination of epiplakin (EPPK) by gene targeting in mice results in acceleration of keratinocyte migration during wound healing, suggesting that epithelial cellular EPPK may be important for the regulation of cellular motility. To study the function of EPPK, we developed EPPK knock-down (KD) and EPPK-overexpressing HeLa cells and analyzed cellular phenotypes and motility by fluorescence/differential interference contrast time-lapse microscopy and immunolocalization of actin and vimentin. Cellular motility of EPPK-KD cells was significantly elevated, but that of EPPK-overexpressing cells was obviously depressed. Many spike-like projections were observed on EPPK-KD cells, with fewer such structures on overexpressing cells. By contrast, in EPPK-KD cells, expression of E-cadherin was unchanged but vimentin fibers were thinner and sparser than in controls, and they were more concentrated at the peri-nucleus, as observed in migrating keratinocytes at wound edges in EPPK(-/-) mice. In Matrigel 3-D cultures, EPPK co-localized on the outer surface of cell clusters with zonula occludens-1 (ZO-1), a marker of tight junctions. Our results suggest that EPPK is associated with the machinery for cellular motility and contributes to tissue architecture via the rearrangement of intermediate filaments.
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Affiliation(s)
- Hiromitsu Shimada
- Department of Tumor Genetics and Biology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
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16
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Ishikawa K, Sumiyoshi H, Matsuo N, Takeo N, Goto M, Okamoto O, Tatsukawa S, Kitamura H, Fujikura Y, Yoshioka H, Fujiwara S. Epiplakin accelerates the lateral organization of keratin filaments during wound healing. J Dermatol Sci 2010; 60:95-104. [PMID: 20926261 DOI: 10.1016/j.jdermsci.2010.08.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2010] [Revised: 08/03/2010] [Accepted: 08/25/2010] [Indexed: 11/16/2022]
Abstract
BACKGROUND Epiplakin (EPPK) belongs to the plakin family of cytolinker proteins and, resembling other members of the plakin family such as BPAG1 (an autoantigen of bullous pemphigoid) and plectin, EPPK has plakin repeat domains (PRDs) that bind to intermediate filaments. Elimination of EPPK by gene targeting in mice resulted in the acceleration of keratinocyte migration during wound healing. EPPK is expressed in proliferating keratinocytes at wound edges and, in view of its putative function in binding to keratin, we postulated that the keratin network in EPPK-null (EPPK(-/-)) mice might be disrupted during wound healing. OBJECTIVE To examine this hypothesis and to determine the precise localization of EPPK in relation to keratin filaments, we compared the non-wounded and wounded epidermis of wild-type and EPPK(-/-) mice. METHODS Non-wounded epidermis and wounded epidermis from wild-type and EPPK(-/-) mice were examined by immunofluorescence staining and electron microscopy before and after double immunostaining. RESULTS EPPK was colocalized with keratin 17 (K17) more extensively than with other keratins examined in wounded epidermis. The expression of K5, K10, K6, and K17 was the same in EPPK(-/-) mice after wounding as in normal mice, but diameters of keratin filaments were reduced in EPPK(-/-) keratinocytes. Electron microscopy after immunostaining revealed that EPPK colocalized with K5, K10 and K6 after wounding in wild-type mice. CONCLUSION Our data indicate that EPPK accelerates keratin bundling in proliferating keratinocytes during wound healing and suggest that EPPK might contribute to reinforcement of keratin networks under mechanical stress.
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Affiliation(s)
- Kazushi Ishikawa
- Department of Dermatology, Faculty of Medicine, Oita University, Hasama-machi, Oita, Japan
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17
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Lee CH, Coulombe PA. Self-organization of keratin intermediate filaments into cross-linked networks. ACTA ACUST UNITED AC 2009; 186:409-21. [PMID: 19651890 PMCID: PMC2728393 DOI: 10.1083/jcb.200810196] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Keratins, the largest subgroup of intermediate filament (IF) proteins, form a network of 10-nm filaments built from type I/II heterodimers in epithelial cells. A major function of keratin IFs is to protect epithelial cells from mechanical stress. Like filamentous actin, keratin IFs must be cross-linked in vitro to achieve the high level of mechanical resilience characteristic of live cells. Keratins 5 and 14 (K5 and K14), the main pairing occurring in the basal progenitor layer of epidermis and related epithelia, can readily self-organize into large filament bundles in vitro and in vivo. Here, we show that filament self-organization is mediated by multivalent interactions involving distinct regions in K5 and K14 proteins. Self-organization is determined independently of polymerization into 10-nm filaments, but involves specific type I–type II keratin complementarity. We propose that self-organization is a key determinant of the structural support function of keratin IFs in vivo.
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Affiliation(s)
- Chang-Hun Lee
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
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Spazierer D, Raberger J, Gross K, Fuchs P, Wiche G. Stress-induced recruitment of epiplakin to keratin networks increases their resistance to hyperphosphorylation-induced disruption. J Cell Sci 2008; 121:825-33. [PMID: 18285451 DOI: 10.1242/jcs.013755] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Epiplakin is a large (>725 kDa) cytoskeletal protein exclusively expressed in epithelial tissues. It has a unique structure, consisting entirely of plakin repeat domains (PRDs), one of the hallmarks of spectraplakin protein family members. Previous studies, including the phenotypic analyses of knockout mice, failed to reveal the biological function of epiplakin. Using in vitro binding assays, we show here that all but one of the 16 PRDs of mouse epiplakin bind to keratins of basal keratinocytes. Nevertheless, in primary keratinocyte cell cultures, epiplakin only partially colocalized with keratin intermediate filament networks. However, upon application of cellular stress in the form of keratin hyperphosphorylation, osmotic shock or UV irradiation, the entire cytoplasmic epiplakin pool became associated with keratin. In response to such types of stress, epiplakin initially translocated to the still-intact keratin filament network and remained associated with keratin after its disruption and transformation into granular aggregates. Time-course experiments revealed that serine/threonine (okadaic acid) and tyrosine (orthovanadate) phosphatase inhibitor-induced filament disruption in differentiated keratinocytes proceeded faster in epiplakin-deficient cells compared with wild-type cells. Our data suggest that epiplakin plays a role in keratin filament reorganization in response to stress, probably by protecting keratin filaments against disruption in a chaperone-like fashion.
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Affiliation(s)
- Daniel Spazierer
- Department of Molecular Cell Biology, Max F. Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria
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