1
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Weinelt N, Wächtershäuser KN, Celik G, Jeiler B, Gollin I, Zein L, Smith S, Andrieux G, Das T, Roedig J, Feist L, Rotter B, Boerries M, Pampaloni F, van Wijk SJL. LUBAC-mediated M1 Ub regulates necroptosis by segregating the cellular distribution of active MLKL. Cell Death Dis 2024; 15:77. [PMID: 38245534 PMCID: PMC10799905 DOI: 10.1038/s41419-024-06447-6] [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: 08/10/2023] [Revised: 12/22/2023] [Accepted: 01/05/2024] [Indexed: 01/22/2024]
Abstract
Plasma membrane accumulation of phosphorylated mixed lineage kinase domain-like (MLKL) is a hallmark of necroptosis, leading to membrane rupture and inflammatory cell death. Pro-death functions of MLKL are tightly controlled by several checkpoints, including phosphorylation. Endo- and exocytosis limit MLKL membrane accumulation and counteract necroptosis, but the exact mechanisms remain poorly understood. Here, we identify linear ubiquitin chain assembly complex (LUBAC)-mediated M1 poly-ubiquitination (poly-Ub) as novel checkpoint for necroptosis regulation downstream of activated MLKL in cells of human origin. Loss of LUBAC activity inhibits tumor necrosis factor α (TNFα)-mediated necroptosis, not by affecting necroptotic signaling, but by preventing membrane accumulation of activated MLKL. Finally, we confirm LUBAC-dependent activation of necroptosis in primary human pancreatic organoids. Our findings identify LUBAC as novel regulator of necroptosis which promotes MLKL membrane accumulation in human cells and pioneer primary human organoids to model necroptosis in near-physiological settings.
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Affiliation(s)
- Nadine Weinelt
- Institute for Experimental Paediatric Haematology and Oncology (EPHO), Goethe University Frankfurt, Komturstrasse 3a, 60528, Frankfurt am Main, Germany
| | - Kaja Nicole Wächtershäuser
- Physical Biology Group, Buchmann Institute for Molecular Life Sciences (BMLS), Biological Sciences (IZN), Goethe University Frankfurt, Max-von-Laue-Strasse 15, 60438, Frankfurt am Main, Germany
| | - Gulustan Celik
- Institute for Experimental Paediatric Haematology and Oncology (EPHO), Goethe University Frankfurt, Komturstrasse 3a, 60528, Frankfurt am Main, Germany
| | - Birte Jeiler
- Institute for Experimental Paediatric Haematology and Oncology (EPHO), Goethe University Frankfurt, Komturstrasse 3a, 60528, Frankfurt am Main, Germany
| | - Isabelle Gollin
- Institute for Experimental Paediatric Haematology and Oncology (EPHO), Goethe University Frankfurt, Komturstrasse 3a, 60528, Frankfurt am Main, Germany
| | - Laura Zein
- Institute for Experimental Paediatric Haematology and Oncology (EPHO), Goethe University Frankfurt, Komturstrasse 3a, 60528, Frankfurt am Main, Germany
| | - Sonja Smith
- Institute for Experimental Paediatric Haematology and Oncology (EPHO), Goethe University Frankfurt, Komturstrasse 3a, 60528, Frankfurt am Main, Germany
| | - Geoffroy Andrieux
- Institute of Medical Bioinformatics and Systems Medicine, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, 79110, Freiburg, Germany
| | - Tonmoy Das
- Institute of Medical Bioinformatics and Systems Medicine, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, 79110, Freiburg, Germany
| | - Jens Roedig
- Institute for Experimental Paediatric Haematology and Oncology (EPHO), Goethe University Frankfurt, Komturstrasse 3a, 60528, Frankfurt am Main, Germany
| | - Leonard Feist
- GenXPro GmbH, Altenhoeferallee 3, 60438, Frankfurt am Main, Germany
| | - Björn Rotter
- GenXPro GmbH, Altenhoeferallee 3, 60438, Frankfurt am Main, Germany
| | - Melanie Boerries
- Institute of Medical Bioinformatics and Systems Medicine, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, 79110, Freiburg, Germany
- German Cancer Consortium (DKTK) partner site Freiburg and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Francesco Pampaloni
- Physical Biology Group, Buchmann Institute for Molecular Life Sciences (BMLS), Biological Sciences (IZN), Goethe University Frankfurt, Max-von-Laue-Strasse 15, 60438, Frankfurt am Main, Germany
| | - Sjoerd J L van Wijk
- Institute for Experimental Paediatric Haematology and Oncology (EPHO), Goethe University Frankfurt, Komturstrasse 3a, 60528, Frankfurt am Main, Germany.
- German Cancer Consortium (DKTK) partner site Frankfurt/Mainz and German Cancer Research Center (DKFZ), Heidelberg, Germany.
- University Cancer Centre Frankfurt (UCT), University Hospital Frankfurt, Goethe-University Frankfurt, Frankfurt, Germany.
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2
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Wisniewski DJ, Liyasova MS, Korrapati S, Zhang X, Ratnayake S, Chen Q, Gilbert SF, Catalano A, Voeller D, Meerzaman D, Guha U, Porat-Shliom N, Annunziata CM, Lipkowitz S. Flotillin-2 regulates epidermal growth factor receptor activation, degradation by Cbl-mediated ubiquitination, and cancer growth. J Biol Chem 2022; 299:102766. [PMID: 36470425 PMCID: PMC9823131 DOI: 10.1016/j.jbc.2022.102766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 11/21/2022] [Accepted: 11/22/2022] [Indexed: 12/08/2022] Open
Abstract
Epidermal growth factor receptor (EGFR) signaling is frequently dysregulated in various cancers. The ubiquitin ligase Casitas B-lineage lymphoma proto-oncogene (Cbl) regulates degradation of activated EGFR through ubiquitination and acts as an adaptor to recruit proteins required for trafficking. Here, we used stable isotope labeling with amino acids in cell culture mass spectrometry to compare Cbl complexes with or without epidermal growth factor (EGF) stimulation. We identified over a hundred novel Cbl interactors, and a secondary siRNA screen found that knockdown of Flotillin-2 (FLOT2) led to increased phosphorylation and degradation of EGFR upon EGF stimulation in HeLa cells. In PC9 and H441 cells, FLOT2 knockdown increased EGF-stimulated EGFR phosphorylation, ubiquitination, and downstream signaling, reversible by EGFR inhibitor erlotinib. CRISPR knockout (KO) of FLOT2 in HeLa cells confirmed EGFR downregulation, increased signaling, and increased dimerization and endosomal trafficking. Furthermore, we determined that FLOT2 interacted with both Cbl and EGFR. EGFR downregulation upon FLOT2 loss was Cbl dependent, as coknockdown of Cbl and Cbl-b restored EGFR levels. In addition, FLOT2 overexpression decreased EGFR signaling and growth. Overexpression of wildtype (WT) FLOT2, but not the soluble G2A FLOT2 mutant, inhibited EGFR phosphorylation upon EGF stimulation in HEK293T cells. FLOT2 loss induced EGFR-dependent proliferation and anchorage-independent growth. Lastly, FLOT2 KO increased tumor formation and tumor volume in nude mice and NSG mice, respectively. Together, these data demonstrated that FLOT2 negatively regulated EGFR activation and dimerization, as well as its subsequent ubiquitination, endosomal trafficking, and degradation, leading to reduced proliferation in vitro and in vivo.
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Affiliation(s)
- David J Wisniewski
- Women's Malignancies Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
| | - Mariya S Liyasova
- Women's Malignancies Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
| | - Soumya Korrapati
- Women's Malignancies Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
| | - Xu Zhang
- Thoracic and GI Malignancies Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
| | - Shashikala Ratnayake
- Center for Biomedical Informatics and Information Technology, National Cancer Institute, Rockville, Maryland, USA
| | - Qingrong Chen
- Center for Biomedical Informatics and Information Technology, National Cancer Institute, Rockville, Maryland, USA
| | - Samuel F Gilbert
- Women's Malignancies Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
| | - Alexis Catalano
- Women's Malignancies Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
| | - Donna Voeller
- Women's Malignancies Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
| | - Daoud Meerzaman
- Center for Biomedical Informatics and Information Technology, National Cancer Institute, Rockville, Maryland, USA
| | - Udayan Guha
- Thoracic and GI Malignancies Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
| | - Natalie Porat-Shliom
- Thoracic and GI Malignancies Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
| | - Christina M Annunziata
- Women's Malignancies Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
| | - Stanley Lipkowitz
- Women's Malignancies Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA.
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3
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Arnaud T, Rodrigues-Lima F, Viguier M, Deshayes F. Interplay between EGFR, E-cadherin, and PTP1B in epidermal homeostasis. Tissue Barriers 2022:2104085. [PMID: 35875939 PMCID: PMC10364651 DOI: 10.1080/21688370.2022.2104085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022] Open
Abstract
Maintaining epithelial homeostasis is crucial to allow embryo development but also the protective barrier which is ensured by the epidermis. This homeostasis is regulated through the expression of several molecules among which EGFR and E-cadherin which are of major importance. Indeed, defects in the regulation of these proteins lead to abnormalities in cell adhesion, proliferation, differentiation, and migration. Hence, regulation of these two proteins is of the utmost importance as they are involved in numerous skin pathologies and cancers. In the last decades it has been described several pathways of regulation of these two proteins and notably several mechanisms of cross-regulation between these partners. In this review, we aimed to describe the current understanding of the regulation of EGFR and interactions between EGFR and E-cadherin and, in particular, the implication of these cross-regulations in epithelium homeostasis. We pay particular attention to PTP1B, a phosphatase involved in the regulation of EGFR.
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Affiliation(s)
- Tessa Arnaud
- Université Paris Cité, BFA, UMR 8251, CNRS, Paris, France
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4
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Shafiq M, Da Vela S, Amin L, Younas N, Harris DA, Zerr I, Altmeppen HC, Svergun D, Glatzel M. The prion protein and its ligands: Insights into structure-function relationships. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2022; 1869:119240. [PMID: 35192891 DOI: 10.1016/j.bbamcr.2022.119240] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 01/23/2022] [Accepted: 01/28/2022] [Indexed: 06/14/2023]
Abstract
The prion protein is a multifunctional protein that exists in at least two different folding states. It is subject to diverse proteolytic processing steps that lead to prion protein fragments some of which are membrane-bound whereas others are soluble. A multitude of ligands bind to the prion protein and besides proteinaceous binding partners, interaction with metal ions and nucleic acids occurs. Although of great importance, information on structural and functional consequences of prion protein binding to its partners is limited. Here, we will reflect on the structure-function relationship of the prion protein and its binding partners considering the different folding states and prion protein fragments.
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Affiliation(s)
- Mohsin Shafiq
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20251 Hamburg, Germany
| | - Stefano Da Vela
- European Molecular Biology Laboratory (EMBL), Hamburg c/o German Electron Synchrotron (DESY), Notkestraße 85, 22607 Hamburg, Germany
| | - Ladan Amin
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, United States
| | - Neelam Younas
- Department of Neurology, University Medical Center Goettingen, Robert-Koch-str. 40, 37075 Goettingen, Germany
| | - David A Harris
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, United States
| | - Inga Zerr
- Department of Neurology, University Medical Center Goettingen, Robert-Koch-str. 40, 37075 Goettingen, Germany
| | - Hermann C Altmeppen
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20251 Hamburg, Germany
| | - Dmitri Svergun
- European Molecular Biology Laboratory (EMBL), Hamburg c/o German Electron Synchrotron (DESY), Notkestraße 85, 22607 Hamburg, Germany
| | - Markus Glatzel
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20251 Hamburg, Germany.
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5
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Yeung CYC, Dondelinger F, Schoof EM, Georg B, Lu Y, Zheng Z, Zhang J, Hannibal J, Fahrenkrug J, Kjaer M. Circadian regulation of protein cargo in extracellular vesicles. SCIENCE ADVANCES 2022; 8:eabc9061. [PMID: 35394844 PMCID: PMC8993114 DOI: 10.1126/sciadv.abc9061] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 02/17/2022] [Indexed: 05/19/2023]
Abstract
The circadian clock controls many aspects of physiology, but it remains undescribed whether extracellular vesicles (EVs), including exosomes, involved in cell-cell communications between tissues are regulated in a circadian pattern. We demonstrate a 24-hour rhythmic abundance of individual proteins in small EVs using liquid chromatography-mass spectrometry in circadian-synchronized tendon fibroblasts. Furthermore, the release of small EVs enriched in RNA binding proteins was temporally separated from those enriched in cytoskeletal and matrix proteins, which peaked during the end of the light phase. Last, we targeted the protein sorting mechanism in the exosome biogenesis pathway and established (by knockdown of circadian-regulated flotillin-1) that matrix metalloproteinase 14 abundance in tendon fibroblast small EVs is under flotillin-1 regulation. In conclusion, we have identified proteomic time signatures for small EVs released by tendon fibroblasts, which supports the view that the circadian clock regulates protein cargo in EVs involved in cell-cell cross-talk.
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Affiliation(s)
- Ching-Yan Chloé Yeung
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery, Copenhagen University Hospital–Bispebjerg and Frederiksberg, Copenhagen, Denmark
- Center for Healthy Aging, Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
- Corresponding author.
| | - Frank Dondelinger
- Centre for Health Informatics, Computation and Statistics, Lancaster University, Lancaster, UK
| | - Erwin M. Schoof
- Proteomics Core, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Birgitte Georg
- Department of Clinical Biochemistry, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark
| | - Yinhui Lu
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Zhiyong Zheng
- Department of Chemistry, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Jingdong Zhang
- Department of Chemistry, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Jens Hannibal
- Department of Clinical Biochemistry, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark
- Institute of Clinical Medicine, University of Copenhagen, Denmark
| | - Jan Fahrenkrug
- Department of Clinical Biochemistry, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark
| | - Michael Kjaer
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery, Copenhagen University Hospital–Bispebjerg and Frederiksberg, Copenhagen, Denmark
- Center for Healthy Aging, Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
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6
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Arnould H, Baudouin V, Baudry A, Ribeiro LW, Ardila-Osorio H, Pietri M, Caradeuc C, Soultawi C, Williams D, Alvarez M, Crozet C, Djouadi F, Laforge M, Bertho G, Kellermann O, Launay JM, Schmitt-Ulms G, Schneider B. Loss of prion protein control of glucose metabolism promotes neurodegeneration in model of prion diseases. PLoS Pathog 2021; 17:e1009991. [PMID: 34610054 PMCID: PMC8519435 DOI: 10.1371/journal.ppat.1009991] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 10/15/2021] [Accepted: 09/29/2021] [Indexed: 11/18/2022] Open
Abstract
Corruption of cellular prion protein (PrPC) function(s) at the plasma membrane of neurons is at the root of prion diseases, such as Creutzfeldt-Jakob disease and its variant in humans, and Bovine Spongiform Encephalopathies, better known as mad cow disease, in cattle. The roles exerted by PrPC, however, remain poorly elucidated. With the perspective to grasp the molecular pathways of neurodegeneration occurring in prion diseases, and to identify therapeutic targets, achieving a better understanding of PrPC roles is a priority. Based on global approaches that compare the proteome and metabolome of the PrPC expressing 1C11 neuronal stem cell line to those of PrPnull-1C11 cells stably repressed for PrPC expression, we here unravel that PrPC contributes to the regulation of the energetic metabolism by orienting cells towards mitochondrial oxidative degradation of glucose. Through its coupling to cAMP/protein kinase A signaling, PrPC tones down the expression of the pyruvate dehydrogenase kinase 4 (PDK4). Such an event favors the transfer of pyruvate into mitochondria and its conversion into acetyl-CoA by the pyruvate dehydrogenase complex and, thereby, limits fatty acids β-oxidation and subsequent onset of oxidative stress conditions. The corruption of PrPC metabolic role by pathogenic prions PrPSc causes in the mouse hippocampus an imbalance between glucose oxidative degradation and fatty acids β-oxidation in a PDK4-dependent manner. The inhibition of PDK4 extends the survival of prion-infected mice, supporting that PrPSc-induced deregulation of PDK4 activity and subsequent metabolic derangements contribute to prion diseases. Our study posits PDK4 as a potential therapeutic target to fight against prion diseases.
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Affiliation(s)
- Hélène Arnould
- INSERM, UMR-S 1124, Paris, France
- Université de Paris, UMR-S 1124, Paris, France
| | - Vincent Baudouin
- INSERM, UMR-S 1124, Paris, France
- Université de Paris, UMR-S 1124, Paris, France
| | - Anne Baudry
- INSERM, UMR-S 1124, Paris, France
- Université de Paris, UMR-S 1124, Paris, France
| | - Luiz W. Ribeiro
- INSERM, UMR-S 1124, Paris, France
- Université de Paris, UMR-S 1124, Paris, France
| | | | - Mathéa Pietri
- INSERM, UMR-S 1124, Paris, France
- Université de Paris, UMR-S 1124, Paris, France
| | - Cédric Caradeuc
- CNRS, UMR 8601, Paris, France
- Université de Paris, UMR 8601, Paris, France
| | - Cynthia Soultawi
- INSERM, UMR-S 1124, Paris, France
- Université de Paris, UMR-S 1124, Paris, France
| | - Declan Williams
- University of Toronto, Tanz Centre for Research in Neurodegenerative Diseases, Canada
| | - Marjorie Alvarez
- INSERM, UMR-S 1124, Paris, France
- Université de Paris, UMR-S 1124, Paris, France
| | - Carole Crozet
- IRMB, Université de Montpellier, INSERM, CHU de Montpellier, Montpellier, France
| | - Fatima Djouadi
- INSERM, UMR-S 1138, Paris, France
- Université de Paris, UMR-S 1138, Paris, France
| | - Mireille Laforge
- INSERM, UMR-S 1124, Paris, France
- Université de Paris, UMR-S 1124, Paris, France
| | - Gildas Bertho
- CNRS, UMR 8601, Paris, France
- Université de Paris, UMR 8601, Paris, France
| | - Odile Kellermann
- INSERM, UMR-S 1124, Paris, France
- Université de Paris, UMR-S 1124, Paris, France
| | - Jean-Marie Launay
- Assistance Publique des Hôpitaux de Paris, INSERM UMR942, Hôpital Lariboisière, Paris, France
- Pharma Research Department, Hoffmann La Roche Ltd, Basel, Switzerland
| | - Gerold Schmitt-Ulms
- University of Toronto, Tanz Centre for Research in Neurodegenerative Diseases, Canada
| | - Benoit Schneider
- INSERM, UMR-S 1124, Paris, France
- Université de Paris, UMR-S 1124, Paris, France
- * E-mail:
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7
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Abstract
Flotillins 1 and 2 are two ubiquitous, highly conserved homologous proteins that assemble to form heterotetramers at the cytoplasmic face of the plasma membrane in cholesterol- and sphingolipid-enriched domains. Flotillin heterotetramers can assemble into large oligomers to form molecular scaffolds that regulate the clustering of at the plasma membrane and activity of several receptors. Moreover, flotillins are upregulated in many invasive carcinomas and also in sarcoma, and this is associated with poor prognosis and metastasis formation. When upregulated, flotillins promote plasma membrane invagination and induce an endocytic pathway that allows the targeting of cargo proteins in the late endosomal compartment in which flotillins accumulate. These late endosomes are not degradative, and participate in the recycling and secretion of protein cargos. The cargos of this Upregulated Flotillin–Induced Trafficking (UFIT) pathway include molecules involved in signaling, adhesion, and extracellular matrix remodeling, thus favoring the acquisition of an invasive cellular behavior leading to metastasis formation. Thus, flotillin presence from the plasma membrane to the late endosomal compartment influences the activity, and even modifies the trafficking and fate of key protein cargos, favoring the development of diseases, for instance tumors. This review summarizes the current knowledge on flotillins and their role in cancer development focusing on their function in cellular membrane remodeling and vesicular trafficking regulation.
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8
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Cooperation and Interplay between EGFR Signalling and Extracellular Vesicle Biogenesis in Cancer. Cells 2020; 9:cells9122639. [PMID: 33302515 PMCID: PMC7764760 DOI: 10.3390/cells9122639] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 11/30/2020] [Accepted: 12/02/2020] [Indexed: 12/13/2022] Open
Abstract
Epidermal growth factor receptor (EGFR) takes centre stage in carcinogenesis throughout its entire cellular trafficking odyssey. When loaded in extracellular vesicles (EVs), EGFR is one of the key proteins involved in the transfer of information between parental cancer and bystander cells in the tumour microenvironment. To hijack EVs, EGFR needs to play multiple signalling roles in the life cycle of EVs. The receptor is involved in the biogenesis of specific EV subpopulations, it signals as an active cargo, and it can influence the uptake of EVs by recipient cells. EGFR regulates its own inclusion in EVs through feedback loops during disease progression and in response to challenges such as hypoxia, epithelial-to-mesenchymal transition and drugs. Here, we highlight how the spatiotemporal rules that regulate EGFR intracellular function intersect with and influence different EV biogenesis pathways and discuss key regulatory features and interactions of this interplay. We also elaborate on outstanding questions relating to EGFR-driven EV biogenesis and available methods to explore them. This mechanistic understanding will be key to unravelling the functional consequences of direct anti-EGFR targeted and indirect EGFR-impacting cancer therapies on the secretion of pro-tumoural EVs and on their effects on drug resistance and microenvironment subversion.
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9
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Cellular Prion Protein (PrPc): Putative Interacting Partners and Consequences of the Interaction. Int J Mol Sci 2020; 21:ijms21197058. [PMID: 32992764 PMCID: PMC7583789 DOI: 10.3390/ijms21197058] [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: 07/31/2020] [Revised: 09/20/2020] [Accepted: 09/23/2020] [Indexed: 02/08/2023] Open
Abstract
Cellular prion protein (PrPc) is a small glycosylphosphatidylinositol (GPI) anchored protein most abundantly found in the outer leaflet of the plasma membrane (PM) in the central nervous system (CNS). PrPc misfolding causes neurodegenerative prion diseases in the CNS. PrPc interacts with a wide range of protein partners because of the intrinsically disordered nature of the protein’s N-terminus. Numerous studies have attempted to decipher the physiological role of the prion protein by searching for proteins which interact with PrPc. Biochemical characteristics and biological functions both appear to be affected by interacting protein partners. The key challenge in identifying a potential interacting partner is to demonstrate that binding to a specific ligand is necessary for cellular physiological function or malfunction. In this review, we have summarized the intracellular and extracellular interacting partners of PrPc and potential consequences of their binding. We also briefly describe prion disease-related mutations at the end of this review.
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10
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Thalwieser Z, Király N, Fonódi M, Csortos C, Boratkó A. Protein phosphatase 2A-mediated flotillin-1 dephosphorylation up-regulates endothelial cell migration and angiogenesis regulation. J Biol Chem 2019; 294:20196-20206. [PMID: 31753918 DOI: 10.1074/jbc.ra119.007980] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 11/04/2019] [Indexed: 12/31/2022] Open
Abstract
Endothelial cells have key functions in endothelial barrier integrity and in responses to angiogenic signals that promote cell proliferation, cell migration, cytoskeletal reorganization, and formation of new blood vessels. These functions highly depend on protein-protein interactions in cell-cell junction and cell attachment complexes and on interactions with cytoskeletal proteins. Protein phosphatase 2A (PP2A) dephosphorylates several target proteins involved in cytoskeletal dynamics and cell adhesion. Our goal was to find new interacting and substrate proteins of the PP2A-B55α holoenzyme in bovine pulmonary endothelial cells. Using LC-MS/MS analysis, we identified flotillin-1 as a protein that binds recombinant GSH S-transferase-tagged PP2A-B55α. Immunoprecipitation experiments, proximity ligation assays, and immunofluorescent staining confirmed the interaction between these two endogenous proteins in endothelial cells. Originally, flotillins were described as regulatory proteins for axon regeneration, but they appear to function in many cellular processes, such as membrane receptor signaling, endocytosis, and cell adhesion. Ser315 is a known PKC-targeted site in flotillin-1. Utilizing phosphomutants of flotillin-1 and the NanoBiT luciferase assay, we show here that phosphorylation/dephosphorylation of Ser315 in flotillin-1 significantly affects its interaction with PP2A-B55α and that PP2A-B55α dephosphorylates phospho-Ser315 Spreading, attachment, migration, and in vitro tube formation rates of S315A variant-overexpressing cells were faster than those of nontransfected or S315D-transfected cells. These results indicate that the PP2A-flotillin-1 interaction identified here affects major physiological activities of pulmonary endothelial cells.
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Affiliation(s)
- Zsófia Thalwieser
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Egyetem tér 1, 4032 Debrecen, Hungary
| | - Nikolett Király
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Egyetem tér 1, 4032 Debrecen, Hungary
| | - Márton Fonódi
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Egyetem tér 1, 4032 Debrecen, Hungary
| | - Csilla Csortos
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Egyetem tér 1, 4032 Debrecen, Hungary
| | - Anita Boratkó
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Egyetem tér 1, 4032 Debrecen, Hungary
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11
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Comprehensive Proteomic Analysis Reveals Intermediate Stage of Non-Lesional Psoriatic Skin and Points out the Importance of Proteins Outside this Trend. Sci Rep 2019; 9:11382. [PMID: 31388062 PMCID: PMC6684579 DOI: 10.1038/s41598-019-47774-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 06/28/2019] [Indexed: 11/15/2022] Open
Abstract
To better understand the pathomechanism of psoriasis, a comparative proteomic analysis was performed with non-lesional and lesional skin from psoriasis patients and skin from healthy individuals. Strikingly, 79.9% of the proteins that were differentially expressed in lesional and healthy skin exhibited expression levels in non-lesional skin that were within twofold of the levels observed in healthy and lesional skin, suggesting that non-lesional skin represents an intermediate stage. Proteins outside this trend were categorized into three groups: I. proteins in non-lesional skin exhibiting expression similar to lesional skin, which might be predisposing factors (i.e., CSE1L, GART, MYO18A and UGDH); II. proteins that were differentially expressed in non-lesional and lesional skin but not in healthy and lesional skin, which might be non-lesional characteristic alteration (i.e., CHCHD6, CHMP5, FLOT2, ITGA7, LEMD2, NOP56, PLVAP and RRAS); and III. proteins with contrasting differential expression in non-lesional and lesional skin compared to healthy skin, which might contribute to maintaining the non-lesional state (i.e., ITGA7, ITGA8, PLVAP, PSAPL1, SMARCA5 and XP32). Finally, proteins differentially expressed in lesions may indicate increased sensitivity to stimuli, peripheral nervous system alterations, furthermore MYBBP1A and PRKDC were identified as potential regulators of key pathomechanisms, including stress and immune response, proliferation and differentiation.
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Beckert B, Panico F, Pollmann R, Eming R, Banning A, Tikkanen R. Immortalized Human hTert/KER-CT Keratinocytes a Model System for Research on Desmosomal Adhesion and Pathogenesis of Pemphigus Vulgaris. Int J Mol Sci 2019; 20:ijms20133113. [PMID: 31247885 PMCID: PMC6651391 DOI: 10.3390/ijms20133113] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 06/24/2019] [Accepted: 06/24/2019] [Indexed: 12/18/2022] Open
Abstract
Pemphigus Vulgaris is an autoimmune disease that results in blister formation in the epidermis and in mucosal tissues due to antibodies recognizing desmosomal cadherins, mainly desmoglein-3 and -1. Studies on the molecular mechanisms of Pemphigus have mainly been carried out using the spontaneously immortalized human keratinocyte cell line HaCaT or in primary keratinocytes. However, both cell systems have suboptimal features, with HaCaT cells exhibiting a large number of chromosomal aberrations and mutated p53 tumor suppressor, whereas primary keratinocytes are short-lived, heterogeneous and not susceptible to genetic modifications due to their restricted life-span. We have here tested the suitability of the commercially available human keratinocyte cell line hTert/KER-CT as a model system for research on epidermal cell adhesion and Pemphigus pathomechanisms. We here show that hTert cells exhibit a calcium dependent expression of desmosomal cadherins and are well suitable for typical assays used for studies on Pemphigus, such as sequential detergent extraction and Dispase-based dissociation assay. Treatment with Pemphigus auto-antibodies results in loss of monolayer integrity and altered localization of desmoglein-3, as well as loss of colocalization with flotillin-2. Our findings demonstrate that hTert cells are well suitable for studies on epidermal cell adhesion and Pemphigus pathomechanisms.
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Affiliation(s)
- Benedikt Beckert
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
| | - Francesca Panico
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
| | - Robert Pollmann
- Department of Dermatology and Allergology, Philipps-Universität Marburg, Baldingerstraße, 35043 Marburg, Germany
| | - Rüdiger Eming
- Department of Dermatology and Allergology, Philipps-Universität Marburg, Baldingerstraße, 35043 Marburg, Germany
| | - Antje Banning
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
| | - Ritva Tikkanen
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany.
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Kessler EL, van Stuijvenberg L, van Bavel JJA, van Bennekom J, Zwartsen A, Rivaud MR, Vink A, Efimov IR, Postma AV, van Tintelen JP, Remme CA, Vos MA, Banning A, de Boer TP, Tikkanen R, van Veen TAB. Flotillins in the intercalated disc are potential modulators of cardiac excitability. J Mol Cell Cardiol 2018; 126:86-95. [PMID: 30452906 DOI: 10.1016/j.yjmcc.2018.11.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 11/12/2018] [Accepted: 11/13/2018] [Indexed: 01/24/2023]
Abstract
BACKGROUND The intercalated disc (ID) is important for cardiac remodeling and has become a subject of intensive research efforts. However, as yet the composition of the ID has still not been conclusively resolved and the role of many proteins identified in the ID, like Flotillin-2, is often unknown. The Flotillin proteins are known to be involved in the stabilization of cadherins and desmosomes in the epidermis and upon cancer development. However, their role in the heart has so far not been investigated. Therefore, in this study, we aimed at identifying the role of Flotillin-1 and Flotillin-2 in the cardiac ID. METHODS Location of Flotillins in human and murine cardiac tissue was evaluated by fluorescent immunolabeling and co-immunoprecipitation. In addition, the effect of Flotillin knockout (KO) on proteins of the ID and in electrical excitation and conduction was investigated in cardiac samples of wildtype (WT), Flotillin-1 KO, Flotilin-2 KO and Flotilin-1/2 double KO mice. Consequences of Flotillin knockdown (KD) on cardiac function were studied (patch clamp and Multi Electrode Array (MEA)) in neonatal rat cardiomyocytes (NRCMs) transfected with siRNAs against Flotillin-1 and/or Flotillin-2. RESULTS First, we confirmed presence in the ID and mutual binding of Flotillin-1 and Flotillin-2 in murine and human cardiac tissue. Flotillin KO mice did not show cardiac fibrosis, nor hypertrophy or changes in expression of the desmosomal ID proteins. However, protein expression of the cardiac sodium channel NaV1.5 was significantly decreased in Flotillin-1 and Flotillin-1/2 KO mice compared to WT mice. In addition, sodium current density showed a significant decrease upon Flotillin-1/2 KD in NRCMs as compared to scrambled siRNA-transfected NRCMs. MEA recordings of Flotillin-2 KD NRCM cultures showed a significantly decreased spike amplitude and a tendency of a reduced spike slope when compared to control and scrambled siRNA-transfected cultures. CONCLUSIONS In this study, we demonstrate the presence of Flotillin-1, in addition to Flotillin-2 in the cardiac ID. Our findings indicate a modulatory role of Flotillins on NaV1.5 expression at the ID, with potential consequences for cardiac excitation.
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Affiliation(s)
- Elise L Kessler
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, the Netherlands.
| | - Leonie van Stuijvenberg
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Joanne J A van Bavel
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Joëlle van Bennekom
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Anne Zwartsen
- Dutch Poisons Information Center (DPIC), University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands; Neurotoxicology Research Group, Division Toxicology, Institute for Risk Assessment Sciences (IRAS), Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
| | - Mathilde R Rivaud
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Aryan Vink
- Department of Pathology, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Igor R Efimov
- Department of Biomedical Engineering, George Washington University, Washington, DC, USA
| | - Alex V Postma
- Department of Clinical Genetics, Amsterdam University Medical Center, Location AMC, the Netherlands
| | - J Peter van Tintelen
- Department of Clinical Genetics, Amsterdam University Medical Center, Location AMC, the Netherlands; Department of Genetics, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Carol A Remme
- Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, the Netherlands
| | - Marc A Vos
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Antje Banning
- Institute of Biochemistry, Medical Faculty, University of Giessen, Germany
| | - Teun P de Boer
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Ritva Tikkanen
- Institute of Biochemistry, Medical Faculty, University of Giessen, Germany
| | - Toon A B van Veen
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, the Netherlands
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Petrova V, Eva R. The Virtuous Cycle of Axon Growth: Axonal Transport of Growth-Promoting Machinery as an Intrinsic Determinant of Axon Regeneration. Dev Neurobiol 2018; 78:898-925. [PMID: 29989351 DOI: 10.1002/dneu.22608] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 05/25/2018] [Accepted: 05/26/2018] [Indexed: 02/02/2023]
Abstract
Injury to the brain and spinal cord has devastating consequences because adult central nervous system (CNS) axons fail to regenerate. Injury to the peripheral nervous system (PNS) has a better prognosis, because adult PNS neurons support robust axon regeneration over long distances. CNS axons have some regenerative capacity during development, but this is lost with maturity. Two reasons for the failure of CNS regeneration are extrinsic inhibitory molecules, and a weak intrinsic capacity for growth. Extrinsic inhibitory molecules have been well characterized, but less is known about the neuron-intrinsic mechanisms which prevent axon re-growth. Key signaling pathways and genetic/epigenetic factors have been identified which can enhance regenerative capacity, but the precise cellular mechanisms mediating their actions have not been characterized. Recent studies suggest that an important prerequisite for regeneration is an efficient supply of growth-promoting machinery to the axon; however, this appears to be lacking from non-regenerative axons in the adult CNS. In the first part of this review, we summarize the evidence linking axon transport to axon regeneration. We discuss the developmental decline in axon regeneration capacity in the CNS, and comment on how this is paralleled by a similar decline in the selective axonal transport of regeneration-associated receptors such as integrins and growth factor receptors. In the second part, we discuss the mechanisms regulating selective polarized transport within neurons, how these relate to the intrinsic control of axon regeneration, and whether they can be targeted to enhance regenerative capacity. © 2018 Wiley Periodicals, Inc. Develop Neurobiol 00: 000-000, 2018.
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Affiliation(s)
- Veselina Petrova
- John Van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 OPY, United Kingdom
| | - Richard Eva
- John Van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 OPY, United Kingdom
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Leighton PLA, Kanyo R, Neil GJ, Pollock NM, Allison WT. Prion gene paralogs are dispensable for early zebrafish development and have nonadditive roles in seizure susceptibility. J Biol Chem 2018; 293:12576-12592. [PMID: 29903907 DOI: 10.1074/jbc.ra117.001171] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 06/07/2018] [Indexed: 11/06/2022] Open
Abstract
Normally folded prion protein (PrPC) and its functions in healthy brains remain underappreciated compared with the intense study of its misfolded forms ("prions," PrPSc) during the pathobiology of prion diseases. This impedes the development of therapeutic strategies in Alzheimer's and prion diseases. Disrupting the zebrafish homologs of PrPC has provided novel insights; however, mutagenesis of the zebrafish paralog prp2 did not recapitulate previous dramatic developmental phenotypes, suggesting redundancy with the prp1 paralog. Here, we generated zebrafish prp1 loss-of-function mutant alleles and dual prp1-/-;prp2-/- mutants. Zebrafish prp1-/- and dual prp1-/-;prp2-/- mutants resemble mammalian Prnp knockouts insofar as they lack overt phenotypes, which surprisingly contrasts with reports of severe developmental phenotypes when either prp1 or prp2 is knocked down acutely. Previous studies suggest that PrPC participates in neural cell development/adhesion, including in zebrafish where loss of prp2 affects adhesion and deposition patterns of lateral line neuromasts. In contrast with the expectation that prp1's functions would be redundant to prp2, they appear to have opposing functions in lateral line neurodevelopment. Similarly, loss of prp1 blunted the seizure susceptibility phenotypes observed in prp2 mutants, contrasting the expected exacerbation of phenotypes if these prion gene paralogs were serving redundant roles. In summary, prion mutant fish lack the overt phenotypes previously predicted, and instead they have subtle phenotypes similar to mammals. No evidence was found for functional redundancy in the zebrafish prion gene paralogs, and the phenotypes observed when each gene is disrupted individually are consistent with ancient functions of prion proteins in neurodevelopment and modulation of neural activity.
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Affiliation(s)
- Patricia L A Leighton
- From the Department of Biological Sciences and the Centre for Prion and Protein Folding Diseases, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Richard Kanyo
- From the Department of Biological Sciences and the Centre for Prion and Protein Folding Diseases, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Gavin J Neil
- From the Department of Biological Sciences and the Centre for Prion and Protein Folding Diseases, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Niall M Pollock
- From the Department of Biological Sciences and the Centre for Prion and Protein Folding Diseases, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - W Ted Allison
- From the Department of Biological Sciences and the Centre for Prion and Protein Folding Diseases, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
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He L, Sayers EJ, Watson P, Jones AT. Contrasting roles for actin in the cellular uptake of cell penetrating peptide conjugates. Sci Rep 2018; 8:7318. [PMID: 29743505 PMCID: PMC5943252 DOI: 10.1038/s41598-018-25600-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 04/25/2018] [Indexed: 12/13/2022] Open
Abstract
The increased need for macromolecular therapeutics, such as peptides, proteins and nucleotides, to reach intracellular targets necessitates more effective delivery vectors and a higher level of understanding of their mechanism of action. Cell penetrating peptides (CPPs) can transport a range of macromolecules into cells, either through direct plasma membrane translocation or endocytosis. All known endocytic pathways involve cell-cortex remodelling, a process shown to be regulated by reorganisation of the actin cytoskeleton. Here using flow cytometry, confocal microscopy and a variety of actin inhibitors we identify how actin disorganisation in different cell types differentially influences the cellular entry of three probes: the CPP octaarginine - Alexa488 conjugate (R8-Alexa488), octaarginine conjugated Enhanced Green Fluorescent Protein (EGFP-R8), and the fluid phase probe dextran. Disrupting actin organisation in A431 skin epithelial cells dramatically increases the uptake of EGFP-R8 and dextran, and contrasts strongly to inhibitory effects observed with transferrin and R8 attached to the fluorophore Alexa488. This demonstrates that uptake of the same CPP can occur via different endocytic processes depending on the conjugated fluorescent entity. Overall this study highlights how cargo influences cell uptake of this peptide and that the actin cytoskeleton may act as a gateway or barrier to endocytosis of drug delivery vectors.
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Affiliation(s)
- L He
- Cardiff School of Pharmacy and Pharmaceutical Sciences, Redwood Building, Cardiff University, Cardiff, Wales, CF10 3NB, UK
| | - E J Sayers
- Cardiff School of Pharmacy and Pharmaceutical Sciences, Redwood Building, Cardiff University, Cardiff, Wales, CF10 3NB, UK
| | - P Watson
- Cardiff School of Biosciences, The Sir Martin Evans Building, Cardiff University, Cardiff, Wales, CF10 3AX, UK.
| | - A T Jones
- Cardiff School of Pharmacy and Pharmaceutical Sciences, Redwood Building, Cardiff University, Cardiff, Wales, CF10 3NB, UK.
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17
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Rousset M, Leturque A, Thenet S. The nucleo-junctional interplay of the cellular prion protein: A new partner in cancer-related signaling pathways? Prion 2017; 10:143-52. [PMID: 27216988 DOI: 10.1080/19336896.2016.1163457] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The cellular prion protein PrP(c) plays important roles in proliferation, cell death and survival, differentiation and adhesion. The participation of PrP(c) in tumor growth and metastasis was pointed out, but the underlying mechanisms were not deciphered completely. In the constantly renewing intestinal epithelium, our group demonstrated a dual localization of PrP(c), which is targeted to cell-cell junctions in interaction with Src kinase and desmosomal proteins in differentiated enterocytes, but is predominantly nuclear in dividing cells. While the role of PrP(c) in the dynamics of intercellular junctions was confirmed in other biological systems, we unraveled its function in the nucleus only recently. We identified several nuclear PrP(c) partners, which comprise γ-catenin, one of its desmosomal partners, β-catenin and TCF7L2, the main effectors of the canonical Wnt pathway, and YAP, one effector of the Hippo pathway. PrP(c) up-regulates the activity of the β-catenin/TCF7L2 complex and its invalidation impairs the proliferation of intestinal progenitors. We discuss how PrP(c) could participate to oncogenic processes through its interaction with Wnt and Hippo pathway effectors, which are controlled by cell-cell junctions and Src family kinases and dysregulated during tumorigenesis. This highlights new potential mechanisms that connect PrP(c) expression and subcellular redistribution to cancer.
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Affiliation(s)
- Monique Rousset
- a Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers , Paris , France ;,b INSERM, UMR_S 1138, Centre de Recherche des Cordeliers , Paris , France ;,c Université Paris Descartes, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers , Paris , France
| | - Armelle Leturque
- a Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers , Paris , France ;,b INSERM, UMR_S 1138, Centre de Recherche des Cordeliers , Paris , France ;,c Université Paris Descartes, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers , Paris , France
| | - Sophie Thenet
- a Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers , Paris , France ;,b INSERM, UMR_S 1138, Centre de Recherche des Cordeliers , Paris , France ;,c Université Paris Descartes, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers , Paris , France ;,d EPHE, PSL Research University, Laboratoire de Pharmacologie Cellulaire et Moléculaire , Paris , France
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Solis GP, Bilousov O, Koval A, Lüchtenborg AM, Lin C, Katanaev VL. Golgi-Resident Gαo Promotes Protrusive Membrane Dynamics. Cell 2017; 170:939-955.e24. [PMID: 28803726 DOI: 10.1016/j.cell.2017.07.015] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 05/30/2017] [Accepted: 07/13/2017] [Indexed: 10/19/2022]
Abstract
To form protrusions like neurites, cells must coordinate their induction and growth. The first requires cytoskeletal rearrangements at the plasma membrane (PM), the second requires directed material delivery from cell's insides. We find that the Gαo-subunit of heterotrimeric G proteins localizes dually to PM and Golgi across phyla and cell types. The PM pool of Gαo induces, and the Golgi pool feeds, the growing protrusions by stimulated trafficking. Golgi-residing KDELR binds and activates monomeric Gαo, atypically for G protein-coupled receptors that normally act on heterotrimeric G proteins. Through multidimensional screenings identifying > 250 Gαo interactors, we pinpoint several basic cellular activities, including vesicular trafficking, as being regulated by Gαo. We further find small Golgi-residing GTPases Rab1 and Rab3 as direct effectors of Gαo. This KDELR → Gαo → Rab1/3 signaling axis is conserved from insects to mammals and controls material delivery from Golgi to PM in various cells and tissues.
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Affiliation(s)
- Gonzalo P Solis
- Department of Pharmacology and Toxicology, University of Lausanne, CH-1011 Lausanne, Switzerland.
| | - Oleksii Bilousov
- Department of Pharmacology and Toxicology, University of Lausanne, CH-1011 Lausanne, Switzerland
| | - Alexey Koval
- Department of Pharmacology and Toxicology, University of Lausanne, CH-1011 Lausanne, Switzerland
| | - Anne-Marie Lüchtenborg
- Department of Pharmacology and Toxicology, University of Lausanne, CH-1011 Lausanne, Switzerland
| | - Chen Lin
- Department of Pharmacology and Toxicology, University of Lausanne, CH-1011 Lausanne, Switzerland
| | - Vladimir L Katanaev
- Department of Pharmacology and Toxicology, University of Lausanne, CH-1011 Lausanne, Switzerland; School of Biomedicine, Far Eastern Federal University, Vladivostok 690950, Russian Federation.
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Hirsch TZ, Martin-Lannerée S, Mouillet-Richard S. Functions of the Prion Protein. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2017; 150:1-34. [PMID: 28838656 DOI: 10.1016/bs.pmbts.2017.06.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Although initially disregarded compared to prion pathogenesis, the functions exerted by the cellular prion protein PrPC have gained much interest over the past two decades. Research aiming at unraveling PrPC functions started to intensify when it became appreciated that it would give clues as to how it is subverted in the context of prion infection and, more recently, in the context of Alzheimer's disease. It must now be admitted that PrPC is implicated in an incredible variety of biological processes, including neuronal homeostasis, stem cell fate, protection against stress, or cell adhesion. It appears that these diverse roles can all be fulfilled through the involvement of PrPC in cell signaling events. Our aim here is to provide an overview of our current understanding of PrPC functions from the animal to the molecular scale and to highlight some of the remaining gaps that should be addressed in future research.
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Affiliation(s)
- Théo Z Hirsch
- INSERM UMR 1124, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, UMR 1124, Paris, France
| | - Séverine Martin-Lannerée
- INSERM UMR 1124, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, UMR 1124, Paris, France
| | - Sophie Mouillet-Richard
- INSERM UMR 1124, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, UMR 1124, Paris, France.
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20
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Liu R, Yang G, Zhou MH, He Y, Mei YA, Ding Y. Flotillin-1 downregulates K(+) current by directly coupling with Kv2.1 subunit. Protein Cell 2017; 7:455-60. [PMID: 27221754 PMCID: PMC4887332 DOI: 10.1007/s13238-016-0276-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Affiliation(s)
- Rui Liu
- School of Life Sciences, Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200438, China
| | - Guang Yang
- School of Life Sciences, Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200438, China
| | - Meng-Hua Zhou
- School of Life Sciences, Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200438, China
| | - Yu He
- School of Life Sciences, Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200438, China
| | - Yan-Ai Mei
- School of Life Sciences, Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200438, China.
| | - Yu Ding
- School of Life Sciences, Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200438, China.
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Taneyhill LA, Schiffmacher AT. Should I stay or should I go? Cadherin function and regulation in the neural crest. Genesis 2017; 55. [PMID: 28253541 DOI: 10.1002/dvg.23028] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 02/21/2017] [Accepted: 02/27/2017] [Indexed: 12/20/2022]
Abstract
Our increasing comprehension of neural crest cell development has reciprocally advanced our understanding of cadherin expression, regulation, and function. As a transient population of multipotent stem cells that significantly contribute to the vertebrate body plan, neural crest cells undergo a variety of transformative processes and exhibit many cellular behaviors, including epithelial-to-mesenchymal transition (EMT), motility, collective cell migration, and differentiation. Multiple studies have elucidated regulatory and mechanistic details of specific cadherins during neural crest cell development in a highly contextual manner. Collectively, these results reveal that gradual changes within neural crest cells are accompanied by often times subtle, yet important, alterations in cadherin expression and function. The primary focus of this review is to coalesce recent data on cadherins in neural crest cells, from their specification to their emergence as motile cells soon after EMT, and to highlight the complexities of cadherin expression beyond our current perceptions, including the hypothesis that the neural crest EMT is a transition involving a predominantly singular cadherin switch. Further advancements in genetic approaches and molecular techniques will provide greater opportunities to integrate data from various model systems in order to distinguish unique or overlapping functions of cadherins expressed at any point throughout the ontogeny of the neural crest.
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Affiliation(s)
- Lisa A Taneyhill
- Department of Animal and Avian Sciences, University of Maryland, College Park, Maryland, 20742
| | - Andrew T Schiffmacher
- Department of Animal and Avian Sciences, University of Maryland, College Park, Maryland, 20742
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Prion Protein Family Contributes to Tumorigenesis via Multiple Pathways. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1018:207-224. [PMID: 29052140 DOI: 10.1007/978-981-10-5765-6_13] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A wealth of evidence suggests that proteins from prion protein (PrP) family contribute to tumorigenesis in many types of cancers, including pancreatic ductal adenocarcinoma (PDAC), breast cancer, glioblastoma, colorectal cancer, gastric cancer, melanoma, etc. It is well documented that PrP is a biomarker for PDAC, breast cancer, and gastric cancer. However, the underlying mechanisms remain unclear. The major reasons for cancer cell-caused patient death are metastasis and multiple drug resistance, both of which connect to physiological functions of PrP expressing in cancer cells. PrP enhances tumorigenesis by multiple pathways. For example, PrP existed as pro-PrP in most of the PDAC cell lines, thus increasing cancer cell motility by binding to cytoskeletal protein filamin A (FLNa). Using PDAC cell lines BxPC-3 and AsPC-1 as model system, we identified that dysfunction of glycosylphosphatidylinositol (GPI) anchor synthesis machinery resulted in the biogenesis of pro-PrP. In addition, in cancer cells without FLNa expression, pro-PrP can modify cytoskeleton structure by affecting cofilin/F-actin axis, thus influencing cancer cell movement. Besides pro-PrP, we showed that GPI-anchored unglycosylated PrP can elevate cell mobility by interacting with VEGFR2, thus stimulating cell migration under serum-free condition. Besides affecting cancer cell motility, overexpressed PrP or doppel (Dpl) in cancer cells has been shown to increase cell proliferation, multiple drug resistance, and angiogenesis, thus, proteins from PrP gene family by affecting important processes via multiple pathways for cancer cell growth exacerbating tumorigenesis.
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Martin-Lannerée S, Halliez S, Hirsch TZ, Hernandez-Rapp J, Passet B, Tomkiewicz C, Villa-Diaz A, Torres JM, Launay JM, Béringue V, Vilotte JL, Mouillet-Richard S. The Cellular Prion Protein Controls Notch Signaling in Neural Stem/Progenitor Cells. Stem Cells 2016; 35:754-765. [PMID: 27641601 DOI: 10.1002/stem.2501] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 08/29/2016] [Accepted: 08/31/2016] [Indexed: 12/26/2022]
Abstract
The prion protein is infamous for its involvement in a group of neurodegenerative diseases known as Transmissible Spongiform Encephalopathies. In the longstanding quest to decipher the physiological function of its cellular isoform, PrPC , the discovery of its participation to the self-renewal of hematopoietic and neural stem cells has cast a new spotlight on its potential role in stem cell biology. However, still little is known on the cellular and molecular mechanisms at play. Here, by combining in vitro and in vivo murine models of PrPC depletion, we establish that PrPC deficiency severely affects the Notch pathway, which plays a major role in neural stem cell maintenance. We document that the absence of PrPC in a neuroepithelial cell line or in primary neurospheres is associated with drastically reduced expression of Notch ligands and receptors, resulting in decreased levels of Notch target genes. Similar alterations of the Notch pathway are recovered in the neuroepithelium of Prnp-/- embryos during a developmental window encompassing neural tube closure. In addition, in line with Notch defects, our data show that the absence of PrPC results in altered expression of Nestin and Olig2 as well as N-cadherin distribution. We further provide evidence that PrPC controls the expression of the epidermal growth factor receptor (EGFR) downstream from Notch. Finally, we unveil a negative feedback action of EGFR on both Notch and PrPC . As a whole, our study delineates a molecular scenario through which PrPC takes part to the self-renewal of neural stem and progenitor cells. Stem Cells 2017;35:754-765.
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Affiliation(s)
- Séverine Martin-Lannerée
- INSERM UMR 1124, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, UMR 1124, Paris, France
| | - Sophie Halliez
- VIM, UR 892, INRA, Université Paris-Saclay, Jouy-en-Josas, France
| | - Théo Z Hirsch
- INSERM UMR 1124, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, UMR 1124, Paris, France
| | - Julia Hernandez-Rapp
- INSERM UMR 1124, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, UMR 1124, Paris, France
| | - Bruno Passet
- Department of Pharma Research, INRA UMR 1313, Génétique animale et biologie intégrative, Jouy-en-Josas, France
| | - Céline Tomkiewicz
- INSERM UMR 1124, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, UMR 1124, Paris, France
| | - Ana Villa-Diaz
- Centro de Investigación en Sanidad Animal-INIA, U 942 Madrid, Spain
| | | | - Jean-Marie Launay
- AP-HP Service de Biochimie, Fondation FondaMental, INSERM U942 Hôpital Lariboisière, Paris, France.,Pharma Research Department, F. Hoffmann-La-Roche Ltd, Basel, Switzerland
| | - Vincent Béringue
- VIM, UR 892, INRA, Université Paris-Saclay, Jouy-en-Josas, France
| | - Jean-Luc Vilotte
- Department of Pharma Research, INRA UMR 1313, Génétique animale et biologie intégrative, Jouy-en-Josas, France
| | - Sophie Mouillet-Richard
- INSERM UMR 1124, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, UMR 1124, Paris, France
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24
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Law ME, Ferreira RB, Davis BJ, Higgins PJ, Kim JS, Castellano RK, Chen S, Luesch H, Law BK. CUB domain-containing protein 1 and the epidermal growth factor receptor cooperate to induce cell detachment. Breast Cancer Res 2016; 18:80. [PMID: 27495374 PMCID: PMC4974783 DOI: 10.1186/s13058-016-0741-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 07/22/2016] [Indexed: 01/01/2023] Open
Abstract
Background While localized malignancies often respond to available therapies, most disseminated cancers are refractory. Novel approaches, therefore, are needed for the treatment of metastatic disease. CUB domain-containing protein1 (CDCP1) plays an important role in metastasis and drug resistance; the mechanism however, is poorly understood. Methods Breast cancer cell lines were engineered to stably express EGFR, CDCP1 or phosphorylation site mutants of CDCP1. These cell lines were used for immunoblot analysis or affinity purification followed by immunoblot analysis to assess protein phosphorylation and/or protein complex formation with CDCP1. Kinase activity was evaluated using phosphorylation site-specific antibodies and immunoblot analysis in in vitro kinase assays. Protein band excision and mass spectrometry was utilized to further identify proteins complexed with CDCP1 or ΔCDCP1, which is a mimetic of the cleaved form of CDCP1. Cell detachment was assessed using cell counting. Results This paper reports that CDCP1 forms ternary protein complexes with Src and EGFR, facilitating Src activation and Src-dependent EGFR transactivation. Importantly, we have discovered that a class of compounds termed Disulfide bond Disrupting Agents (DDAs) blocks CDCP1/EGFR/Src ternary complex formation and downstream signaling. CDCP1 and EGFR cooperate to induce detachment of breast cancer cells from the substratum and to disrupt adherens junctions. Analysis of CDCP1-containing complexes using proteomics techniques reveals that CDCP1 associates with several proteins involved in cell adhesion, including adherens junction and desmosomal cadherins, and cytoskeletal elements. Conclusions Together, these results suggest that CDCP1 may facilitate loss of adhesion by promoting activation of EGFR and Src at sites of cell-cell and cell-substratum contact. Electronic supplementary material The online version of this article (doi:10.1186/s13058-016-0741-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Mary E Law
- Department of Pharmacology and Therapeutics, University of Florida, Acad. Res. Bldg., Room R5-210, 1200 Newell Drive, P.O. Box 100267, Gainesville, FL, 32610, USA.,UF-Health Cancer Center, University of Florida, Gainesville, FL, 32610, USA
| | - Renan B Ferreira
- Department of Chemistry, University of Florida, Gainesville, FL, 32611, USA
| | - Bradley J Davis
- Department of Pharmacology and Therapeutics, University of Florida, Acad. Res. Bldg., Room R5-210, 1200 Newell Drive, P.O. Box 100267, Gainesville, FL, 32610, USA.,UF-Health Cancer Center, University of Florida, Gainesville, FL, 32610, USA
| | - Paul J Higgins
- Center for Cell Biology and Cancer Research, Albany Medical College, Albany, NY, 12208, USA
| | - Jae-Sung Kim
- Department of Surgery, University of Florida, Gainesville, FL, 32610, USA
| | | | - Sixue Chen
- Department of Biology, Interdisciplinary Center for Biotechnology, University of Florida, Gainesville, FL, 32611, USA
| | - Hendrik Luesch
- Department of Medicinal Chemistry, University of Florida, Gainesville, FL, 32610, USA.,Center for Natural Products, Drug Discovery and Development (CNPD3), University of Florida, Gainesville, FL, 32610, USA
| | - Brian K Law
- Department of Pharmacology and Therapeutics, University of Florida, Acad. Res. Bldg., Room R5-210, 1200 Newell Drive, P.O. Box 100267, Gainesville, FL, 32610, USA. .,UF-Health Cancer Center, University of Florida, Gainesville, FL, 32610, USA. .,Center for Natural Products, Drug Discovery and Development (CNPD3), University of Florida, Gainesville, FL, 32610, USA.
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25
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4.1N is involved in a flotillin-1/β-catenin/Wnt pathway and suppresses cell proliferation and migration in non-small cell lung cancer cell lines. Tumour Biol 2016; 37:12713-12723. [DOI: 10.1007/s13277-016-5146-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 07/11/2016] [Indexed: 01/14/2023] Open
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26
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Völlner F, Ali J, Kurrle N, Exner Y, Eming R, Hertl M, Banning A, Tikkanen R. Loss of flotillin expression results in weakened desmosomal adhesion and Pemphigus vulgaris-like localisation of desmoglein-3 in human keratinocytes. Sci Rep 2016; 6:28820. [PMID: 27346727 PMCID: PMC4922016 DOI: 10.1038/srep28820] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 06/09/2016] [Indexed: 01/01/2023] Open
Abstract
Desmosomes are adhesion plaques that mediate cell-cell adhesion in many tissues, including the epidermis, and generate mechanical resistance to tissues. The extracellular domains of desmosomal cadherin proteins, desmogleins and desmocollins, are required for the interaction with cadherins of the neighbouring cells, whereas their cytoplasmic tails associate with cytoplasmic proteins which mediate connection to intermediate filaments. Disruption of desmosomal adhesion by mutations, autoantibodies or bacterial toxins results in severe human disorders of e.g. the skin and the heart. Despite the vital role of desmosomes in various tissues, the details of their molecular assembly are not clear. We here show that the two members of the flotillin protein family directly interact with the cytoplasmic tails of desmogleins. Depletion of flotillins in human keratinocytes results in weakened desmosomal adhesion and reduced expression of desmoglein-3, most likely due to a reduction in the desmosomal pool due to increased turnover. In the absence of flotillins, desmoglein-3 shows an altered localisation pattern in the cell-cell junctions of keratinocytes, which is highly similar to the localisation observed upon treatment with pemphigus vulgaris autoantibodies. Thus, our data show that flotillins, which have previously been connected to the classical cadherins, are also of importance for the desmosomal cell adhesion.
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Affiliation(s)
- Frauke Völlner
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
| | - Jawahir Ali
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
| | - Nina Kurrle
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
| | - Yvonne Exner
- Department of Dermatology and Allergology, Philipps University of Marburg, Baldingerstrasse, 35043 Marburg, Germany
| | - Rüdiger Eming
- Department of Dermatology and Allergology, Philipps University of Marburg, Baldingerstrasse, 35043 Marburg, Germany
| | - Michael Hertl
- Department of Dermatology and Allergology, Philipps University of Marburg, Baldingerstrasse, 35043 Marburg, Germany
| | - Antje Banning
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
| | - Ritva Tikkanen
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
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27
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Hülsbusch N, Solis GP, Katanaev VL, Stuermer CAO. Reggie-1/Flotillin-2 regulates integrin trafficking and focal adhesion turnover via Rab11a. Eur J Cell Biol 2015; 94:531-45. [PMID: 26299802 DOI: 10.1016/j.ejcb.2015.07.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 07/28/2015] [Accepted: 07/30/2015] [Indexed: 12/24/2022] Open
Abstract
Reggies/flotillins are implicated in trafficking of membrane proteins to their target sites and in the regulation of the Rab11a-dependent targeted recycling of E-cadherin to adherens junctions (AJs). Here we demonstrate a function of reggies in focal adhesion (FA) formation and α5- and β1-integrin recycling to FAs. Downregulation of reggie-1 in HeLa and A431 cells by siRNA and shRNA increased the number of FAs, impaired their distribution and modified FA turnover. This was coupled to enhanced focal adhesion kinase (FAK) and Rac1 signaling and gain in plasma membrane motility. Wild type and constitutively-active (CA) Rab11a rescued the phenotype (normal number of FAs) whereas dominant-negative (DN) Rab11a mimicked the loss-of-reggie phenotype in control cells. That reggie-1 affects integrin trafficking emerged from the faster loss of internalized antibody-labeled β1-integrin in reggie-deficient cells. Moreover, live imaging using TIRF microscopy revealed vesicles containing reggie-1 and α5- or β1-integrin, trafficking close to the substrate-near membrane and making kiss-and-run contacts with FAs. Thus, reggie-1 in interaction with Rab11a controls Rac1 and FAK activation and coordinates the targeted recycling of α5- and β1-integrins to FAs to regulate FA formation and membrane dynamics.
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Affiliation(s)
- Nikola Hülsbusch
- Department of Biology, University of Konstanz, 78467 Konstanz, Germany.
| | - Gonzalo P Solis
- Department of Pharmacology and Toxicology, University of Lausanne, CH-1005 Lausanne, Switzerland
| | - Vladimir L Katanaev
- Department of Pharmacology and Toxicology, University of Lausanne, CH-1005 Lausanne, Switzerland
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28
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Flot-2 Expression Correlates with EGFR Levels and Poor Prognosis in Surgically Resected Non-Small Cell Lung Cancer. PLoS One 2015; 10:e0132190. [PMID: 26161893 PMCID: PMC4498790 DOI: 10.1371/journal.pone.0132190] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 06/10/2015] [Indexed: 11/29/2022] Open
Abstract
We previously reported that expression of Flotillin 2 (Flot-2), a protein isolated from caveolae/lipid raft domains, increased significantly in nasopharyngeal carcinoma (NPC) compared with normal tissues. Signal transduction through epidermal growth factor receptors (EGFR) and Flot-2 play an important role in cancer development, but their precise role in lung cancer has not been investigated. In this study, we have investigated the correlation between the expression of Flot-2 and EGFR, which increase significantly in non-small cell lung cancer (NSCLC) patients (n=352) compared with non-cancer tissues. Additionally, patients with advanced stages of NSCLC had higher positive expression of Flot-2 and EGFR than patients with early stages. NSCLC patients with increased expression of Flot-2 and EGFR had significantly less overall survival rates than patients with less expression of Flot-2 and EGFR. Taken together, our data suggest that increased expression of Flot-2 and EGFR in NSCLC patients is inversely proportional to the disease prognosis and that increased expression of Flot-2 associated with increased EGFR may serve as a biomarker to predict poor disease prognosis.
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29
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Wen Q, Alnemah MM, Luo J, Wang W, Chu S, Chen L, Li J, Xu L, Li M, Zhou J, Fan S. FLOT-2 is an independent prognostic marker in oral squamous cell carcinoma. INTERNATIONAL JOURNAL OF CLINICAL AND EXPERIMENTAL PATHOLOGY 2015; 8:8236-8243. [PMID: 26339392 PMCID: PMC4555720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Accepted: 06/22/2015] [Indexed: 06/05/2023]
Abstract
Flotillin-2 (Flot-2) is an important component of cellular membrane, which involves in various cellular processes and recent studies have revealed that Flot-2 played important roles in cancer progression. The expression and prognostic impact of Flot-2 in oral squamous cell carcinoma (OSCC) have not been well studied. So, a tissue microarray (TMA) based on immunohistochemical analysis of surgical resection of tumor tissues of 78 cases of OSCC patients and 27 cases of adjacent non-cancerous squamous epithelium tissues was conducted. This study focused on detecting Flot-2 expression and analyzing its prognostic impact on OSCC. The result showed that the positive percentage of Flot-2 expression in OSCC (74.4%, 58/78) was significantly higher than that in adjacent non-cancerous squamous epithelium tissues (25.9%, 7/27) (P<0.001). Additionally, the positive expression of Flot-2 in OSCC patients with a history of alcohol consumption was significantly higher than those nonusers (P=0.027). Both univariate and multivariate survival analysis indicated that increased expression Flot-2 protein was significantly correlated inversely with overall survival rates in OSCC patients (P=0.046, P=0.002). Taken together, positive expression of Flot-2 protein may be an independent biomarker for poor prognosis in OSCC.
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Affiliation(s)
- Qiuyuan Wen
- Department of Pathology, The Second Xiangya Hospital, Central South UniversityChangsha, Hunan, China
| | - Mohannad Ma Alnemah
- Department of Pathology, The Second Xiangya Hospital, Central South UniversityChangsha, Hunan, China
| | - Jiadi Luo
- Department of Pathology, The Second Xiangya Hospital, Central South UniversityChangsha, Hunan, China
| | - Weiyuan Wang
- Department of Pathology, The Second Xiangya Hospital, Central South UniversityChangsha, Hunan, China
| | - Shuzhou Chu
- Department of Pathology, The Second Xiangya Hospital, Central South UniversityChangsha, Hunan, China
| | - Lingjiao Chen
- Department of Pathology, The Second Xiangya Hospital, Central South UniversityChangsha, Hunan, China
| | - Jiao Li
- Department of Pathology, The Second Xiangya Hospital, Central South UniversityChangsha, Hunan, China
| | - Lina Xu
- Department of Pathology, The Second Xiangya Hospital, Central South UniversityChangsha, Hunan, China
| | - Meirong Li
- Department of Pathology, The Second Xiangya Hospital, Central South UniversityChangsha, Hunan, China
| | - Jianhua Zhou
- Department of Pathology, Xiangya School of Medicine, Central South UniversityHunan, China
| | - Songqing Fan
- Department of Pathology, The Second Xiangya Hospital, Central South UniversityChangsha, Hunan, China
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30
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Padmanabhan R, Taneyhill LA. Cadherin-6B undergoes macropinocytosis and clathrin-mediated endocytosis during cranial neural crest cell EMT. J Cell Sci 2015; 128:1773-86. [PMID: 25795298 PMCID: PMC4446736 DOI: 10.1242/jcs.164426] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 03/16/2015] [Indexed: 02/03/2023] Open
Abstract
The epithelial-to-mesenchymal transition (EMT) is important for the formation of migratory neural crest cells during development and is co-opted in human diseases such as cancer metastasis. Chick premigratory cranial neural crest cells lose intercellular contacts, mediated in part by Cadherin-6B (Cad6B), migrate extensively, and later form a variety of adult derivatives. Importantly, modulation of Cad6B is crucial for proper neural crest cell EMT. Although Cad6B possesses a long half-life, it is rapidly lost from premigratory neural crest cell membranes, suggesting the existence of post-translational mechanisms during EMT. We have identified a motif in the Cad6B cytoplasmic tail that enhances Cad6B internalization and reduces the stability of Cad6B upon its mutation. Furthermore, we demonstrate for the first time that Cad6B is removed from premigratory neural crest cells through cell surface internalization events that include clathrin-mediated endocytosis and macropinocytosis. Both of these processes are dependent upon the function of dynamin, and inhibition of Cad6B internalization abrogates neural crest cell EMT and migration. Collectively, our findings reveal the significance of post-translational events in controlling cadherins during neural crest cell EMT and migration.
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Affiliation(s)
| | - Lisa A Taneyhill
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD 20742, USA
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31
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Bodin S, Planchon D, Rios Morris E, Comunale F, Gauthier-Rouvière C. Flotillins in intercellular adhesion - from cellular physiology to human diseases. J Cell Sci 2014; 127:5139-47. [PMID: 25413346 DOI: 10.1242/jcs.159764] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Flotillin 1 and 2 are ubiquitous and highly conserved proteins. They were initially discovered in 1997 as being associated with specific caveolin-independent cholesterol- and glycosphingolipid-enriched membrane microdomains and as being expressed during axon regeneration. Flotillins have a role in a large number of physiopathological processes, mainly through their function in membrane receptor clustering and in the regulation of clathrin-independent endocytosis. In this Commentary, we summarize the research performed so far on the role of flotillins in cell-cell adhesion. Recent studies have demonstrated that flotillins directly regulate the formation of cadherin complexes. Indeed, flotillin microdomains are required for the dynamic association and stabilization of cadherins at cell-cell junctions and also for cadherin signaling. Moreover, because flotillins regulate endocytosis and also the actin cytoskeleton, they could have an indirect role in the assembly and stabilization of cadherin complexes. Because it has also recently been shown that flotillins are overexpressed during neurodegenerative diseases and in human cancers, where their upregulation is associated with metastasis formation and poor prognosis, understanding to what extent flotillin upregulation participates in the development of such pathologies is thus of particular interest, as well as how, at the molecular level, it might affect cell adhesion processes.
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Affiliation(s)
- Stéphane Bodin
- Equipe Labellisée Ligue Contre le Cancer, Universités Montpellier 2 et 1, CRBM, CNRS, UMR 5237, 1919 Route de Mende, 34293 Montpellier, France
| | - Damien Planchon
- Equipe Labellisée Ligue Contre le Cancer, Universités Montpellier 2 et 1, CRBM, CNRS, UMR 5237, 1919 Route de Mende, 34293 Montpellier, France
| | - Eduardo Rios Morris
- Equipe Labellisée Ligue Contre le Cancer, Universités Montpellier 2 et 1, CRBM, CNRS, UMR 5237, 1919 Route de Mende, 34293 Montpellier, France
| | - Franck Comunale
- Equipe Labellisée Ligue Contre le Cancer, Universités Montpellier 2 et 1, CRBM, CNRS, UMR 5237, 1919 Route de Mende, 34293 Montpellier, France
| | - Cécile Gauthier-Rouvière
- Equipe Labellisée Ligue Contre le Cancer, Universités Montpellier 2 et 1, CRBM, CNRS, UMR 5237, 1919 Route de Mende, 34293 Montpellier, France
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32
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Halliez S, Passet B, Martin-Lannerée S, Hernandez-Rapp J, Laude H, Mouillet-Richard S, Vilotte JL, Béringue V. To develop with or without the prion protein. Front Cell Dev Biol 2014; 2:58. [PMID: 25364763 PMCID: PMC4207017 DOI: 10.3389/fcell.2014.00058] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 09/22/2014] [Indexed: 12/23/2022] Open
Abstract
The deletion of the cellular form of the prion protein (PrPC) in mouse, goat, and cattle has no drastic phenotypic consequence. This stands in apparent contradiction with PrPC quasi-ubiquitous expression and conserved primary and tertiary structures in mammals, and its pivotal role in neurodegenerative diseases such as prion and Alzheimer's diseases. In zebrafish embryos, depletion of PrP ortholog leads to a severe loss-of-function phenotype. This raises the question of a potential role of PrPC in the development of all vertebrates. This view is further supported by the early expression of the PrPC encoding gene (Prnp) in many tissues of the mouse embryo, the transient disruption of a broad number of cellular pathways in early Prnp−/− mouse embryos, and a growing body of evidence for PrPC involvement in the regulation of cell proliferation and differentiation in various types of mammalian stem cells and progenitors. Finally, several studies in both zebrafish embryos and in mammalian cells and tissues in formation support a role for PrPC in cell adhesion, extra-cellular matrix interactions and cytoskeleton. In this review, we summarize and compare the different models used to decipher PrPC functions at early developmental stages during embryo- and organo-genesis and discuss their relevance.
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Affiliation(s)
- Sophie Halliez
- Institut National de la Recherche Agronomique, U892 Virologie et Immunologie Moléculaires Jouy-en-Josas, France
| | - Bruno Passet
- Institut National de la Recherche Agronomique, UMR1313 Génétique Animale et Biologie Intégrative Jouy-en-Josas, France
| | - Séverine Martin-Lannerée
- Institut National de la Santé et de la Recherche Médicale, UMR-S1124 Paris, France ; Université Paris Descartes, Sorbonne Paris Cité, UMR-S1124 Paris, France
| | - Julia Hernandez-Rapp
- Institut National de la Santé et de la Recherche Médicale, UMR-S1124 Paris, France ; Université Paris Descartes, Sorbonne Paris Cité, UMR-S1124 Paris, France
| | - Hubert Laude
- Institut National de la Recherche Agronomique, U892 Virologie et Immunologie Moléculaires Jouy-en-Josas, France
| | - Sophie Mouillet-Richard
- Institut National de la Santé et de la Recherche Médicale, UMR-S1124 Paris, France ; Université Paris Descartes, Sorbonne Paris Cité, UMR-S1124 Paris, France
| | - Jean-Luc Vilotte
- Institut National de la Recherche Agronomique, UMR1313 Génétique Animale et Biologie Intégrative Jouy-en-Josas, France
| | - Vincent Béringue
- Institut National de la Recherche Agronomique, U892 Virologie et Immunologie Moléculaires Jouy-en-Josas, France
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33
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Wen Q, Li J, Wang W, Xie G, Xu L, Luo J, Chu S, She L, Li D, Huang D, Fan S. Increased expression of flotillin-2 protein as a novel biomarker for lymph node metastasis in nasopharyngeal carcinoma. PLoS One 2014; 9:e101676. [PMID: 25014228 PMCID: PMC4094483 DOI: 10.1371/journal.pone.0101676] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 06/09/2014] [Indexed: 11/18/2022] Open
Abstract
Nasopharyngeal carcinoma (NPC) is a head and neck malignant tumor rare throughout most of the world but common in Southeast Asia, especially in Southern China. Flotillin-2 (Flot-2) is not only an important component of cellular membrane, but also involves in various cellular processes such as membrane trafficking, T cell and B cell activation, regulation of several signaling pathways associated with cell growth and malignant transformation, keeping structure and junction of epidermal cells and formation of filopodia. Although such molecular effects of Flot-2 have been reported, whether the expression of Flot-2 protein is associated with clinicopathologic implication for NPC has not been reported. The purpose of this research is to investigate the expression of Flot-2 protein in NPC and control nasopharyngeal epithelial tissues by immunohistochemistry and elucidate the association between the expression of Flot-2 protein and clinicopathological characteristics of NPC. The results showed that the positive percentage of Flot-2 expression in the NPC, nasopharyngeal epithelia with atypical hyperplasia and in the control nasopharyngeal mucosa epithelia was 88.8% (119/134), 76.9% (10/13) and 5.7% (5/88), respectively. There was significantly higher expression of Flot-2 protein in NPC and nasopharyngeal epithelia with atypical hyperplasia compared to the control nasopharyngeal mucosa epithelia (P<0.001, respectively). The positive percentage of Flot-2 protein expression in NPC patients with lymph node metastasis was significantly higher than those without lymph node metastasis. Increasing of Flot-2 expression was obviously correlated with clinical stages of NPC patients. The expression of Flot-2 was proved to be the independent predicted factor for lymph node metastasis by multivariate analysis. The sensitivity of Flot-2 for predicting lymph node metastasis of NPC patients was 93%. Taken together, our results suggest that the increased expression of Flot-2 protein is a novel higher sensitivity biomarker that can predict lymph node metastases in NPC.
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Affiliation(s)
- Qiuyuan Wen
- Department of Pathology, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Jiao Li
- Department of Pathology, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Weiyuan Wang
- Department of Pathology, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Guiyuan Xie
- Department of Oncology, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Lina Xu
- Department of Pathology, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Jiadi Luo
- Department of Pathology, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Shuzhou Chu
- Department of Pathology, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Lei She
- Department of Pathology, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Duo Li
- Department of Pathology, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Donghai Huang
- Department of Otorhinolaryngology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Songqing Fan
- Department of Pathology, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China
- * E-mail:
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Meister M, Tikkanen R. Endocytic trafficking of membrane-bound cargo: a flotillin point of view. MEMBRANES 2014; 4:356-71. [PMID: 25019426 PMCID: PMC4194039 DOI: 10.3390/membranes4030356] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Revised: 06/28/2014] [Accepted: 07/02/2014] [Indexed: 12/03/2022]
Abstract
The ubiquitous and highly conserved flotillin proteins, flotillin-1 and flotillin-2, have been shown to be involved in various cellular processes such as cell adhesion, signal transduction through receptor tyrosine kinases as well as in cellular trafficking pathways. Due to the fact that flotillins are acylated and form hetero-oligomers, they constitutively associate with cholesterol-enriched lipid microdomains. In recent years, such microdomains have been appreciated as platforms that participate in endocytosis and other cellular trafficking steps. This review summarizes the current findings on the role of flotillins in membrane-bound cargo endocytosis and endosomal trafficking events. We will discuss the proposed function of flotillins in endocytosis in the light of recent findings that point towards a role for flotillins in a step that precedes the actual endocytic uptake of cargo molecules. Recent findings have also revealed that flotillins may be important for endosomal sorting and recycling of specific cargo molecules. In addition to these aspects, the cellular trafficking pathway of flotillins themselves as potential cargo in the context of growth factor signaling will be discussed.
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Affiliation(s)
- Melanie Meister
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany.
| | - Ritva Tikkanen
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany.
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Petit CSV, Besnier L, Morel E, Rousset M, Thenet S. Roles of the cellular prion protein in the regulation of cell-cell junctions and barrier function. Tissue Barriers 2014; 1:e24377. [PMID: 24665391 PMCID: PMC3887058 DOI: 10.4161/tisb.24377] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 03/18/2013] [Accepted: 03/19/2013] [Indexed: 01/12/2023] Open
Abstract
The cellular prion protein was historically characterized owing to its misfolding in prion disease. Although its physiological role remains incompletely understood, PrP(C) has emerged as an evolutionary conserved, multifaceted protein involved in a wide-range of biological processes. PrP(C) is a GPI-anchored protein targeted to the plasma membrane, in raft microdomains, where its interaction with a repertoire of binding partners, which differ depending on cell models, mediates its functions. Among identified PrP(C) partners are cell adhesion molecules. This review will focus on the multiple implications of PrP(C) in cell adhesion processes, mainly the regulation of cell-cell junctions in epithelial and endothelial cells and the consequences on barrier properties. We will show how recent findings argue for a role of PrP(C) in the recruitment of signaling molecules, which in turn control the targeting or the stability of adhesion complexes at the plasma membrane.
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Affiliation(s)
- Constance S V Petit
- Centre de Recherche des Cordeliers; Université Pierre et Marie Curie; Paris, France ; INSERM; Paris, France ; Université Paris Descartes; Paris, France
| | - Laura Besnier
- Centre de Recherche des Cordeliers; Université Pierre et Marie Curie; Paris, France ; INSERM; Paris, France ; Université Paris Descartes; Paris, France
| | - Etienne Morel
- Centre de Recherche des Cordeliers; Université Pierre et Marie Curie; Paris, France ; INSERM; Paris, France ; Université Paris Descartes; Paris, France
| | - Monique Rousset
- Centre de Recherche des Cordeliers; Université Pierre et Marie Curie; Paris, France ; INSERM; Paris, France ; Université Paris Descartes; Paris, France
| | - Sophie Thenet
- Centre de Recherche des Cordeliers; Université Pierre et Marie Curie; Paris, France ; INSERM; Paris, France ; Université Paris Descartes; Paris, France ; Ecole Pratique des Hautes Etudes; Laboratoire de Pharmacologie Cellulaire et Moléculaire ; Paris, France
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Asp N, Pust S, Sandvig K. Flotillin depletion affects ErbB protein levels in different human breast cancer cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:1987-96. [PMID: 24747692 DOI: 10.1016/j.bbamcr.2014.04.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 04/08/2014] [Accepted: 04/10/2014] [Indexed: 10/25/2022]
Abstract
The ErbB3 receptor is an important regulator of cell growth and carcinogenesis. Among breast cancer patients, up to 50-70% have ErbB3 overexpression and 20-30% show overexpressed or amplified ErbB2. ErbB3 has also been implicated in the development of resistance to several drugs used against cancers driven by ErbB1 or ErbB2. One of the main challenges in ErbB-targeting therapy is to inactivate signaling mediated by ErbB2-ErbB3 oncogenic receptor complexes. We analyzed the regulatory role of flotillins on ErbB3 levels and ErbB2-ErbB3 complexes in SKBR3, MCF7 and MDA-MB-134-VI human breast cancer cells. Recently, we described a mechanism for interfering with ErbB2 signaling in breast cancer and demonstrated a molecular complex of flotillin scaffolding proteins with ErbB2 and Hsp90. In the present study, flotillins were found to be in a molecular complex with ErbB3, even in cells without the presence of ErbB2 or other ErbB receptors. Depletion of either flotillin-1 or flotillin-2 resulted in downregulation of ErbB3 and a selective reduction of ErbB2-ErbB3 receptor complexes. Moreover, flotillin-2 depletion resulted in reduced activation of Akt and MAPK signaling cascades, and as a functional consequence of flotillin depletion, breast cancer cells showed an impaired cell migration. Altogether, we provide data demonstrating a novel and functional role of flotillins in the regulation of ErbB protein levels and stabilization of ErbB2-ErbB3 receptor complexes. Thus, flotillins are crucial regulators for oncogenic ErbB function and potential targets for cancer treatment.
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Affiliation(s)
- Nagham Asp
- Department of Biochemistry, Institute for Cancer Research, Oslo University Hospital, 0379 Oslo, Norway; Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, 0379 Oslo, Norway
| | - Sascha Pust
- Department of Biochemistry, Institute for Cancer Research, Oslo University Hospital, 0379 Oslo, Norway; Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, 0379 Oslo, Norway.
| | - Kirsten Sandvig
- Department of Biochemistry, Institute for Cancer Research, Oslo University Hospital, 0379 Oslo, Norway; Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, 0379 Oslo, Norway; Department of Molecular Biosciences, Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway
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Flotillins in receptor tyrosine kinase signaling and cancer. Cells 2014; 3:129-49. [PMID: 24709906 PMCID: PMC3980747 DOI: 10.3390/cells3010129] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 02/11/2014] [Accepted: 02/12/2014] [Indexed: 01/23/2023] Open
Abstract
Flotillins are highly conserved proteins that localize into specific cholesterol rich microdomains in cellular membranes. They have been shown to be associated with, for example, various signaling pathways, cell adhesion, membrane trafficking and axonal growth. Recent findings have revealed that flotillins are frequently overexpressed in various types of human cancers. We here review the suggested functions of flotillins during receptor tyrosine kinase signaling and in cancer. Although flotillins have been implicated as putative cancer therapy targets, we here show that great caution is required since flotillin ablation may result in effects that increase instead of decrease the activity of specific signaling pathways. On the other hand, as flotillin overexpression appears to be related with metastasis formation in certain cancers, we also discuss the implications of these findings for future therapy aspects.
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Lee TH, McKleroy W, Khalifeh-Soltani A, Sakuma S, Lazarev S, Riento K, Nishimura SL, Nichols BJ, Atabai K. Functional genomic screen identifies novel mediators of collagen uptake. Mol Biol Cell 2014; 25:583-93. [PMID: 24403604 PMCID: PMC3937085 DOI: 10.1091/mbc.e13-07-0382] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Tissue fibrosis occurs when matrix production outpaces matrix degradation. Degradation of collagen, the main component of fibrotic tissue, is mediated through an extracellular proteolytic pathway and intracellular pathway of cellular uptake and lysosomal digestion. Recent studies demonstrate that disruption of the intracellular pathways can exacerbate fibrosis. These pathways are poorly characterized. Here we identify novel mediators of the intracellular pathway of collagen turnover through a genome-wide RNA interference screen in Drosophila S2 cells. Screening of 7505 Drosophila genes conserved among metazoans identified 22 genes that were required for efficient internalization of type I collagen. These included proteins involved in vesicle transport, the actin cytoskeleton, and signal transduction. We show further that the flotillin genes have a conserved and central role in collagen uptake in Drosophila and human cells. Short hairpin RNA-mediated silencing of flotillins in human monocyte and fibroblasts impaired collagen uptake by promoting lysosomal degradation of the endocytic collagen receptors uPARAP/Endo180 and mannose receptor. These data provide an initial characterization of intracellular pathways of collagen turnover and identify the flotillin genes as critical regulators of this process. A better understanding of these pathways may lead to novel therapies that reduce fibrosis by increasing collagen turnover.
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Affiliation(s)
- Ting-Hein Lee
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158 Department of Medicine, University of California, San Francisco, San Francisco, CA 94158 Lung Biology Center, University of California, San Francisco, San Francisco, CA 94158 Department of Pathology, University of California, San Francisco, San Francisco, CA 94158 MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
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Kurrle N, Völlner F, Eming R, Hertl M, Banning A, Tikkanen R. Flotillins directly interact with γ-catenin and regulate epithelial cell-cell adhesion. PLoS One 2013; 8:e84393. [PMID: 24391950 PMCID: PMC3877284 DOI: 10.1371/journal.pone.0084393] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 11/14/2013] [Indexed: 12/23/2022] Open
Abstract
Flotillin-1 and flotillin-2 are two homologous, membrane raft associated proteins. Although it has been reported that flotillins are involved in cell adhesion processes and play a role during breast cancer progression, thus making them interesting future therapeutic targets, their precise function has not been well elucidated. The present study investigates the function of these proteins in cell-cell adhesion in non-malignant cells. We have used the non-malignant epithelial MCF10A cells to study the interaction network of flotillins within cell-cell adhesion complexes. RNA interference was used to examine the effect of flotillins on the structure of adherens junctions and on the association of core proteins, such as E-cadherin, with membrane rafts. We here show that the cadherin proteins of the adherens junction associate with flotillin-2 in MCF10A cells and in various human cell lines. In vitro, flotillin-1 and flotillin-2 directly interact with γ-catenin which is so far the only protein known to be present both in the adherens junction and the desmosome. Mapping of the interaction domain within the γ-catenin sequence identified the Armadillo domains 6-8, especially ARM domain 7, to be important for the association with flotillins. Furthermore, depletion of flotillins significantly influenced the morphology of the adherens junction in human epithelial MCF10A cells and altered the association of E-cadherin and γ-catenin with membrane rafts. Taken together, these observations suggest a functional role for flotillins, especially flotillin-2, in cell-cell adhesion in non-malignant epithelial cells.
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Affiliation(s)
- Nina Kurrle
- Institute of Biochemistry, Medical Faculty, Justus Liebig University, Giessen, Germany
| | - Frauke Völlner
- Institute of Biochemistry, Medical Faculty, Justus Liebig University, Giessen, Germany
| | - Rüdiger Eming
- Department of Dermatology and Allergology, Phillips University, Marburg, Germany
| | - Michael Hertl
- Department of Dermatology and Allergology, Phillips University, Marburg, Germany
| | - Antje Banning
- Institute of Biochemistry, Medical Faculty, Justus Liebig University, Giessen, Germany
| | - Ritva Tikkanen
- Institute of Biochemistry, Medical Faculty, Justus Liebig University, Giessen, Germany
- * E-mail:
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40
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Kurrle N, Ockenga W, Meister M, Völlner F, Kühne S, John BA, Banning A, Tikkanen R. Phosphatidylinositol 3-Kinase dependent upregulation of the epidermal growth factor receptor upon Flotillin-1 depletion in breast cancer cells. BMC Cancer 2013; 13:575. [PMID: 24304721 PMCID: PMC4235219 DOI: 10.1186/1471-2407-13-575] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 11/29/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Flotillin-1 and flotillin-2 are two homologous and ubiquitously expressed proteins that are involved in signal transduction and membrane trafficking. Recent studies have reported that flotillins promote breast cancer progression, thus making them interesting targets for breast cancer treatment. In the present study, we have investigated the underlying molecular mechanisms of flotillins in breast cancer. METHODS Human adenocarcinoma MCF7 breast cancer cells were stably depleted of flotillins by means of lentivirus mediated short hairpin RNAs. Western blotting, immunofluorescence and quantitative real-time PCR were used to analyze the expression of proteins of the epidermal growth factor receptor (EGFR) family. Western blotting was used to investigate the effect of EGFR stimulation or inhibition as well as phosphatidylinositol 3-kinase (PI3K) inhibition on mitogen activated protein kinase (MAPK) signaling. Rescue experiments were performed by stable transfection of RNA intereference resistant flotillin proteins. RESULTS We here show that stable knockdown of flotillin-1 in MCF7 cells resulted in upregulation of EGFR mRNA and protein expression and hyperactivation of MAPK signaling, whereas ErbB2 and ErbB3 expression were not affected. Treatment of the flotillin knockdown cells with an EGFR inhibitor reduced the MAPK signaling, demonstrating that the increased EGFR expression and activity is the cause of the increased signaling. Stable ectopic expression of flotillins in the knockdown cells reduced the increased EGFR expression, demonstrating a direct causal relationship between flotillin-1 expression and EGFR amount. Furthermore, the upregulation of EGFR was dependent on the PI3K signaling pathway which is constitutively active in MCF7 cells, and PI3K inhibition resulted in reduced EGFR expression. CONCLUSIONS This study demonstrates that flotillins may not be suitable as cancer therapy targets in cells that carry certain other oncogenic mutations such as PI3K activating mutations, as unexpected effects are prone to emerge upon flotillin knockdown which may even facilitate cancer cell growth and proliferation.
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Affiliation(s)
- Nina Kurrle
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
| | - Wymke Ockenga
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
| | - Melanie Meister
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
| | - Frauke Völlner
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
| | - Sina Kühne
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
| | - Bincy A John
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
| | - Antje Banning
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
| | - Ritva Tikkanen
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
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41
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Guizzunti G, Zurzolo C. The fate of PrP GPI-anchor signal peptide is modulated by P238S pathogenic mutation. Traffic 2013; 15:78-93. [PMID: 24112521 DOI: 10.1111/tra.12126] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2013] [Revised: 09/24/2013] [Accepted: 10/01/2013] [Indexed: 12/30/2022]
Abstract
Glycosylphosphatidylinositol (GPI)-anchored proteins are localized to the plasma membrane via a C-terminally linked GPI anchor. The GPI anchor is added concomitantly to the cleavage of the carboxy-terminal GPI-anchor signal sequence, thereby causing the release of a C-terminal hydrophobic peptide, whose fate has not yet been investigated. Here we followed the fate of the GPI-attachment signal of the prion protein (PrP), a protein implicated in various types of transmissible neurodegenerative spongiform encephalopathies (TSE). The PrP GPI-anchor signal sequence shows a remarkable and unusual degree of conservation across the species and contains two point mutations (M232R/T and P238S) that are responsible for genetic forms of prion disorders. We show that the PrP GPI-anchor signal peptide (SP), but not the one from an unrelated GPI-anchored protein (folate receptor), undergoes degradation via the proteasome. Moreover, the P238S point mutation partially protects the PrP GPI-anchor SP from degradation. Our data provide the first attempt to address the fate of a GPI-anchor SP and identify a role for the P238S mutation, suggesting the possibility that the PrP GPI-anchor SP could play a role in neurodegenerative prion diseases.
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Affiliation(s)
- Gianni Guizzunti
- Institut Pasteur, Unité de Trafic Membranaire et Pathogenèse, 25-28 rue du Docteur Roux, 75015, Paris, France
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42
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Morton PE, Hicks A, Nastos T, Santis G, Parsons M. CAR regulates epithelial cell junction stability through control of E-cadherin trafficking. Sci Rep 2013; 3:2889. [PMID: 24096322 PMCID: PMC3791454 DOI: 10.1038/srep02889] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 09/20/2013] [Indexed: 12/13/2022] Open
Abstract
CAR (Coxsackie and Adenovirus Receptor) is the primary docking receptor for typeB coxsackie viruses and subgroup C adenoviruses. CAR is a member of the JAM family of adhesion receptors and is located to both tight and adherens junctions between epithelial cells where it can assemble adhesive contacts through homodimerisation in trans. However, the role of CAR in controlling epithelial junction dynamics remains poorly understood. Here we demonstrate that levels of CAR in human epithelial cells play a key role in determining epithelial cell adhesion through control of E-cadherin stability at cell-cell junctions. Mechanistically, we show that CAR is phosphorylated within the C-terminus by PKCδ and that this in turn controls Src-dependent endocytosis of E-cadherin at cell junctions. This data demonstrates a novel role for CAR in regulating epithelial homeostasis.
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Affiliation(s)
- Penny E Morton
- 1] Division of Asthma, Allergy & Lung Biology, King's College London, 5th Floor Tower Wing, Guy's Hospital Campus, London, United Kingdom [2] Randall Division of Cell and Molecular Biophysics, King's College London, New Hunt's House, Guys Campus, London, United Kingdom
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Ivanov AI, Naydenov NG. Dynamics and regulation of epithelial adherens junctions: recent discoveries and controversies. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 303:27-99. [PMID: 23445808 DOI: 10.1016/b978-0-12-407697-6.00002-7] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Adherens junctions (AJs) are evolutionarily conserved plasma-membrane structures that mediate cell-cell adhesions in multicellular organisms. They are organized by several types of adhesive integral membrane proteins, most notably cadherins and nectins that are clustered and stabilized by a number of cytoplasmic scaffolds. AJs are key regulators of tissue architecture and dynamics via control of cell proliferation, polarity, shape, motility, and survival. They are absolutely critical for normal tissue morphogenesis and their disruption results in pathological abnormalities in different tissues. Although the field of adherens-junction research dramatically progressed in recent years, a number of important questions remain controversial and poorly understood. This review outlines basic principles that regulate organization of AJs in mammalian epithelia and discusses recent advances and standing controversies in the field. A special attention is paid to the regulation of AJs by vesicle trafficking and the intracellular cytoskeleton as well as roles and mechanisms of adherens-junction disruption during tumor progression and tissue inflammation.
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Affiliation(s)
- Andrei I Ivanov
- Department of Human and Molecular Genetics, Virginia Institute of Molecular Medicine, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA.
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Guillaume E, Comunale F, Do Khoa N, Planchon D, Bodin S, Gauthier-Rouvière C. Flotillin microdomains stabilize cadherins at cell-cell junctions. J Cell Sci 2013; 126:5293-304. [PMID: 24046456 DOI: 10.1242/jcs.133975] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Cadherins are essential in many fundamental processes and assemble at regions of cell-cell contact in large macromolecular complexes named adherens junctions. We have identified flotillin 1 and 2 as new partners of the cadherin complexes. We show that flotillins are localised at cell-cell junctions (CCJs) in a cadherin-dependent manner. Flotillins and cadherins are constitutively associated at the plasma membrane and their colocalisation at CCJ increases with CCJ maturation. Using three-dimensional structured illumination super-resolution microscopy, we found that cadherin and flotillin complexes are associated with F-actin bundles at CCJs. The knockdown of flotillins dramatically affected N- and E-cadherin recruitment at CCJs in mesenchymal and epithelial cell types and perturbed CCJ integrity and functionality. Moreover, we determined that flotillins are required for cadherin association with GM1-containing plasma membrane microdomains. This allows p120 catenin binding to the cadherin complex and its stabilization at CCJs. Altogether, these data demonstrate that flotillin microdomains are required for cadherin stabilization at CCJs and for the formation of functional CCJs.
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Affiliation(s)
- Emilie Guillaume
- Equipe Labellisée Ligue Contre le Cancer, Universités Montpellier 2 et 1, CRBM, CNRS, UMR 5237, 1919 Route de Mende, 34293 Montpellier, France
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45
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Conserved roles of the prion protein domains on subcellular localization and cell-cell adhesion. PLoS One 2013; 8:e70327. [PMID: 23936187 PMCID: PMC3729945 DOI: 10.1371/journal.pone.0070327] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 06/17/2013] [Indexed: 11/18/2022] Open
Abstract
Analyses of cultured cells and transgenic mice expressing prion protein (PrP) deletion mutants have revealed that some properties of PrP -such as its ability to misfold, aggregate and trigger neurotoxicity- are controlled by discrete molecular determinants within its protein domains. Although the contributions of these determinants to PrP biosynthesis and turnover are relatively well characterized, it is still unclear how they modulate cellular functions of PrP. To address this question, we used two defined activities of PrP as functional readouts: 1) the recruitment of PrP to cell-cell contacts in Drosophila S2 and human MCF-7 epithelial cells, and 2) the induction of PrP embryonic loss- and gain-of-function phenotypes in zebrafish. Our results show that homologous mutations in mouse and zebrafish PrPs similarly affect their subcellular localization patterns as well as their in vitro and in vivo activities. Among PrP’s essential features, the N-terminal leader peptide was sufficient to drive targeting of our constructs to cell contact sites, whereas lack of GPI-anchoring and N-glycosylation rendered them inactive by blocking their cell surface expression. Importantly, our data suggest that the ability of PrP to homophilically trans-interact and elicit intracellular signaling is primarily encoded in its globular domain, and modulated by its repetitive domain. Thus, while the latter induces the local accumulation of PrPs at discrete punctae along cell contacts, the former counteracts this effect by promoting the continuous distribution of PrP. In early zebrafish embryos, deletion of either domain significantly impaired PrP’s ability to modulate E-cadherin cell adhesion. Altogether, these experiments relate structural features of PrP to its subcellular distribution and in vivo activity. Furthermore, they show that despite their large evolutionary history, the roles of PrP domains and posttranslational modifications are conserved between mouse and zebrafish.
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Solis GP, Hülsbusch N, Radon Y, Katanaev VL, Plattner H, Stuermer CAO. Reggies/flotillins interact with Rab11a and SNX4 at the tubulovesicular recycling compartment and function in transferrin receptor and E-cadherin trafficking. Mol Biol Cell 2013; 24:2689-702. [PMID: 23825023 PMCID: PMC3756921 DOI: 10.1091/mbc.e12-12-0854] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
In this study reggie-1/flotillin-2 is identified as a component of the tubulovesicular sorting and recycling compartment, where it interacts with and controls the activity of Rab11a and SNX4. Evidence is given that reggie-1 expression is necessary for the proper recycling of transferrin receptor and E-cadherin in HeLa and A431 cells, respectively. The lipid raft proteins reggie-1 and -2 (flotillins) are implicated in membrane protein trafficking but exactly how has been elusive. We find that reggie-1 and -2 associate with the Rab11a, SNX4, and EHD1–decorated tubulovesicular recycling compartment in HeLa cells and that reggie-1 directly interacts with Rab11a and SNX4. Short hairpin RNA–mediated down-regulation of reggie-1 (and -2) in HeLa cells reduces association of Rab11a with tubular structures and impairs recycling of the transferrin–transferrin receptor (TfR) complex to the plasma membrane. Overexpression of constitutively active Rab11a rescues TfR recycling in reggie-deficient HeLa cells. Similarly, in a Ca2+ switch assay in reggie-depleted A431 cells, internalized E-cadherin is not efficiently recycled to the plasma membrane upon Ca2+ repletion. E-cadherin recycling is rescued, however, by overexpression of constitutively active Rab11a or SNX4 in reggie-deficient A431 cells. This suggests that the function of reggie-1 in sorting and recycling occurs in association with Rab11a and SNX4. Of interest, impaired recycling in reggie-deficient cells leads to de novo E-cadherin biosynthesis and cell contact reformation, showing that cells have ways to compensate the loss of reggies. Together our results identify reggie-1 as a regulator of the Rab11a/SNX4-controlled sorting and recycling pathway, which is, like reggies, evolutionarily conserved.
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Affiliation(s)
- Gonzalo P Solis
- Department of Biology, University of Konstanz, 78467 Konstanz, Germany.
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47
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Llorens F, Carulla P, Villa A, Torres JM, Fortes P, Ferrer I, del Río JA. PrP(C) regulates epidermal growth factor receptor function and cell shape dynamics in Neuro2a cells. J Neurochem 2013; 127:124-38. [PMID: 23638794 DOI: 10.1111/jnc.12283] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Revised: 04/26/2013] [Accepted: 04/27/2013] [Indexed: 01/28/2023]
Abstract
The prion protein (PrP) plays a key role in prion disease pathogenesis. Although the misfolded and pathologic variant of this protein (PrP(SC)) has been studied in depth, the physiological role of PrP(C) remains elusive and controversial. PrP(C) is a cell-surface glycoprotein involved in multiple cellular functions at the plasma membrane, where it interacts with a myriad of partners and regulates several intracellular signal transduction cascades. However, little is known about the gene expression changes modulated by PrP(C) in animals and in cellular models. In this article, we present PrP(C)-dependent gene expression signature in N2a cells and its implication in the most overrepresented functions: cell cycle, cell growth and proliferation, and maintenance of cell shape. PrP(C) over-expression enhances cell proliferation and cell cycle re-entrance after serum stimulation, while PrP(C) silencing slows down cell cycle progression. In addition, MAP kinase and protein kinase B (AKT) pathway activation are under the regulation of PrP(C) in asynchronous cells and following mitogenic stimulation. These effects are due in part to the modulation of epidermal growth factor receptor (EGFR) by PrP(C) in the plasma membrane, where the two proteins interact in a multimeric complex. We also describe how PrP(C) over-expression modulates filopodia formation by Rho GTPase regulation mainly in an AKT-Cdc42-N-WASP-dependent pathway.
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Affiliation(s)
- Franc Llorens
- Molecular and Cellular Neurobiotechnology Group, Institute for Bioengineering of Catalonia (IBEC), Barcelona Science Park, Barcelona, Spain; Department of Cell Biology, University of Barcelona (UB), Barcelona, Spain; Center for Networker Biomedical Research in Neurodegenerative Diseases (CIBERNED), Barcelona, Spain; Institute of Neuropathology, Bellvitge Biomedical Research Institute, Hospitalet de Llobregat, Spain
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48
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Wnt secretion and gradient formation. Int J Mol Sci 2013; 14:5130-45. [PMID: 23455472 PMCID: PMC3634490 DOI: 10.3390/ijms14035130] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 02/20/2013] [Accepted: 02/22/2013] [Indexed: 12/14/2022] Open
Abstract
Concentration gradients formed by the lipid-modified morphogens of the Wnt family are known for their pivotal roles during embryogenesis and adult tissue homeostasis. Wnt morphogens are also implicated in a variety of human diseases, especially cancer. Therefore, the signaling cascades triggered by Wnts have received considerable attention during recent decades. However, how Wnts are secreted and how concentration gradients are formed remains poorly understood. The use of model organisms such as Drosophila melanogaster has provided important advances in this area. For instance, we have previously shown that the lipid raft-associated reggie/flotillin proteins influence Wnt secretion and spreading in Drosophila. Our work supports the notion that producing cells secrete Wnt molecules in at least two pools: a poorly diffusible one and a reggie/flotillin-dependent highly diffusible pool which allows morphogen spreading over long distances away from its source of production. Here we revise the current views of Wnt secretion and spreading, and propose two models for the role of the reggie/flotillin proteins in these processes: (i) reggies/flotillins regulate the basolateral endocytosis of the poorly diffusible, membrane-bound Wnt pool, which is then sorted and secreted to apical compartments for long-range diffusion, and (ii) lipid rafts organized by reggies/flotillins serve as “dating points” where extracellular Wnt transiently interacts with lipoprotein receptors to allow its capture and further spreading via lipoprotein particles. We further discuss these processes in the context of human breast cancer. A better understanding of these phenomena may be relevant for identification of novel drug targets and therapeutic strategies.
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49
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Identification, localization, and functional implications of the microdomain-forming stomatin family in the ciliated protozoan Paramecium tetraurelia. EUKARYOTIC CELL 2013; 12:529-44. [PMID: 23376944 DOI: 10.1128/ec.00324-12] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The SPFH protein superfamily is assumed to occur universally in eukaryotes, but information from protozoa is scarce. In the Paramecium genome, we found only Stomatins, 20 paralogs grouped in 8 families, STO1 to STO8. According to cDNA analysis, all are expressed, and molecular modeling shows the typical SPFH domain structure for all subgroups. For further analysis we used family-specific sequences for fluorescence and immunogold labeling, gene silencing, and functional tests. With all family members tested, we found a patchy localization at/near the cell surface and on vesicles. The Sto1p and Sto4p families are also associated with the contractile vacuole complex. Sto4p also makes puncta on some food vacuoles and is abundant on vesicles recycling from the release site of spent food vacuoles to the site of nascent food vacuole formation. Silencing of the STO1 family reduces mechanosensitivity (ciliary reversal upon touching an obstacle), thus suggesting relevance for positioning of mechanosensitive channels in the plasmalemma. Silencing of STO4 members increases pulsation frequency of the contractile vacuole complex and reduces phagocytotic activity of Paramecium cells. In summary, Sto1p and Sto4p members seem to be involved in positioning specific superficial and intracellular microdomain-based membrane components whose functions may depend on mechanosensation (extracellular stimuli and internal osmotic pressure).
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50
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Le Bras GF, Taubenslag KJ, Andl CD. The regulation of cell-cell adhesion during epithelial-mesenchymal transition, motility and tumor progression. Cell Adh Migr 2012; 6:365-73. [PMID: 22796940 DOI: 10.4161/cam.21326] [Citation(s) in RCA: 146] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Adherens junctions (AJs) are essential for the maintenance of epithelial homeostasis and a key factor in the regulation of cell migration and tumor progression. AJs maintain cell-cell adhesion by linking transmembrane proteins to the actin cytoskeleton. Additionally, they participate in recruitment of signaling receptors and cytoplasmic proteins to the membrane. During cellular invasion or migration, AJs are dynamically regulated and their composition modified to initiate changes in signaling pathways and cytoskeleton organization involved in cellular motility. Loss of E-cadherin, a key component of AJs, is characteristic of epithelial-mesenchymal-transition (EMT) and is associated with tumor cell invasion. We will review recent findings describing novel mechanisms involved in E-cadherin transcription regulation, endocytosis of E-cadherin and signaling associated with loss of AJs as well as reorganization of the AJ during EMT.
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