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Groh AC, Möller-Kerutt A, Gilhaus K, Höffken V, Nedvetsky P, Kleimann S, Behrens M, Ghosh S, Hansen U, Krahn MP, Ebnet K, Pavenstädt H, Ludwig A, Weide T. PALS1 is a key regulator of the lateral distribution of tight junction proteins in renal epithelial cells. J Cell Sci 2024; 137:jcs261303. [PMID: 38265145 DOI: 10.1242/jcs.261303] [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: 05/03/2023] [Accepted: 12/04/2023] [Indexed: 01/25/2024] Open
Abstract
The evolutionarily conserved apical Crumbs (CRB) complex, consisting of the core components CRB3a (an isoform of CRB3), PALS1 and PATJ, plays a key role in epithelial cell-cell contact formation and cell polarization. Recently, we observed that deletion of one Pals1 allele in mice results in functional haploinsufficiency characterized by renal cysts. Here, to address the role of PALS1 at the cellular level, we generated CRISPR/Cas9-mediated PALS1-knockout MDCKII cell lines. The loss of PALS1 resulted in increased paracellular permeability, indicating an epithelial barrier defect. This defect was associated with a redistribution of several tight junction-associated proteins from bicellular to tricellular contacts. PALS1-dependent localization of tight junction proteins at bicellular junctions required its interaction with PATJ. Importantly, reestablishment of the tight junction belt upon transient F-actin depolymerization or upon Ca2+ removal was strongly delayed in PALS1-deficient cells. Additionally, the cytoskeleton regulator RhoA was redistributed from junctions into the cytosol under PALS1 knockout. Together, our data uncover a critical role of PALS1 in the coupling of tight junction proteins to the F-actin cytoskeleton, which ensures their correct distribution along bicellular junctions and the formation of tight epithelial barrier.
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Affiliation(s)
- Ann-Christin Groh
- University Hospital of Münster (UKM), Internal Medicine D (MedD), Department Molecular Nephrology, Albert-Schweitzer-Campus 1 Building A14, 48149 Münster, Germany
| | - Annika Möller-Kerutt
- University Hospital of Münster (UKM), Internal Medicine D (MedD), Department Molecular Nephrology, Albert-Schweitzer-Campus 1 Building A14, 48149 Münster, Germany
| | - Kevin Gilhaus
- University Hospital of Münster (UKM), Internal Medicine D (MedD), Department Molecular Nephrology, Albert-Schweitzer-Campus 1 Building A14, 48149 Münster, Germany
| | - Verena Höffken
- University Hospital of Münster (UKM), Internal Medicine D (MedD), Department Molecular Nephrology, Albert-Schweitzer-Campus 1 Building A14, 48149 Münster, Germany
| | - Pavel Nedvetsky
- University Hospital of Münster (UKM), Internal Medicine D (MedD), Medical Cell Biology, Albert-Schweitzer-Campus 1 Building A14, 48149 Münster, Germany
| | - Simon Kleimann
- University Hospital of Münster (UKM), Internal Medicine D (MedD), Department Molecular Nephrology, Albert-Schweitzer-Campus 1 Building A14, 48149 Münster, Germany
| | - Malina Behrens
- University Hospital of Münster (UKM), Internal Medicine D (MedD), Department Molecular Nephrology, Albert-Schweitzer-Campus 1 Building A14, 48149 Münster, Germany
| | - Sujasha Ghosh
- School of Biological Sciences and NTU Institute of Structural Biology (NISB), Nanyang Technological University, 60 Nanyang Drive, 637551 Singapore City, Singapore
| | - Uwe Hansen
- University Hospital of Münster, Institute of Musculoskeletal Medicine (IMM), Head Core Facility Electron Microscopy, Domagkstraße 3, 48149 Münster, Germany
| | - Michael P Krahn
- University Hospital of Münster (UKM), Internal Medicine D (MedD), Medical Cell Biology, Albert-Schweitzer-Campus 1 Building A14, 48149 Münster, Germany
| | - Klaus Ebnet
- Institute-associated Research Group "Cell adhesion and cell polarity", Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation (ZMBE), University of Münster, Von-Esmarch-Straße 56, 48149 Münster, Germany
| | - Hermann Pavenstädt
- University Hospital of Münster (UKM), Internal Medicine D (MedD), Department Molecular Nephrology, Albert-Schweitzer-Campus 1 Building A14, 48149 Münster, Germany
| | - Alexander Ludwig
- School of Biological Sciences and NTU Institute of Structural Biology (NISB), Nanyang Technological University, 60 Nanyang Drive, 637551 Singapore City, Singapore
| | - Thomas Weide
- University Hospital of Münster (UKM), Internal Medicine D (MedD), Department Molecular Nephrology, Albert-Schweitzer-Campus 1 Building A14, 48149 Münster, Germany
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2
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Gao H, Wang B, Chen R, Jin Z, Ren L, Yang J, Wang W, Zheng N, Lin R. Effects of hydrogen peroxide on endothelial function in three-dimensional hydrogel vascular model and regulation mechanism of polar protein Par3. Biomed Mater 2022; 17. [PMID: 35901804 DOI: 10.1088/1748-605x/ac8538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 07/28/2022] [Indexed: 11/11/2022]
Abstract
Three-dimensional (3D) cell cultures better reflect the function of endothelial cells (ECs) than two-dimensional (2D) cultures. In recent years, studies have found that ECs cultured in a 3D luminal structure can mimic the biological characteristics and phenotypes of vascular ECs, thus making it more suitable for endothelial dysfunction research. In this study, we used a 3D model and 2D tissue culture polystyrene (TCP) to investigate the effects of cell polarity on hydrogen peroxide (H2O2)-induced endothelial dysfunction and its related mechanisms. We observed the cell morphology, oxidative stress, and barrier and endothelial function of human umbilical vein endothelial cells (HUVECs) in 3D and 2D cultures. We then used Illumina to detect the differentially expressed genes in the 3D-cultured HUVEC with and without H2O2 stimulation, using ClusterProfiler for Gene Ontology (GO) function enrichment analysis and Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway enrichment analysis of differentially expressed genes. Finally, we explored the role and mechanism of polar protein partitioning defective protein 3 (Par3) in the regulation of ECs. ECs were inoculated into the 3D hydrogel channel; after stimulation with H2O2, the morphology of HUVECs changed, the boundary was blurred, the expression of intercellular junction proteins decreased, and the barrier function of the EC layer was damaged. 3D culture increased the oxidative stress response of cells stimulated by H2O2 compared to 2D TCPs. The polarity-related protein Par3 and cell division control protein 42 (CDC42) were screened using bioinformatics analysis, and western blotting was used to verify the results. Par3 knockdown significantly suppressed claudin1 (CLDN1) and vascular endothelial cadherin (VE-cadherin). These results suggest that the polar protein Par3 can protect H2O2-induced vascular ECs from damage by regulating CLDN1 and VE-cadherin.
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Affiliation(s)
- Hongqian Gao
- Xi'an Jiaotong University, Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061,Shaanxi, P. R. China, Xi'an, Shaanxi, 710061, CHINA
| | - Bo Wang
- Xi'an Jiaotong University, Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061,Shaanxi, P. R. China, Xi'an, Shaanxi, 710061, CHINA
| | - Ruomeng Chen
- Mechanical and electrical engineering department, Tangshan university, Mechanical and electrical engineering department, Tangshan university, Tang Shan 063000, Hebei, P. R. China, Tangshan, 063000, CHINA
| | - Zhen Jin
- Department of Pharmacology, Xi'an Jiaotong University Health Science Center, Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061,Shaanxi, P. R. China, Xi'an, 710061, CHINA
| | - Lingxuan Ren
- Department of Pharmacology, Xi'an Jiaotong University Health Science Center, Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061,Shaanxi, P. R. China, Xi'an, 710061, CHINA
| | - Jianjun Yang
- Department of Pharmacology, Xi'an Jiaotong University Health Science Center, Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061,Shaanxi, P. R. China, Xi'an, 710061, CHINA
| | - Weirong Wang
- Xi'an Jiaotong University, Department of Medical Laboratory Animal Science, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China, Xi'an, Shaanxi, 710061, CHINA
| | - Nanbo Zheng
- Department of Pharmacology, Xi'an Jiaotong University School of Basic Medical Sciences, Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061,Shaanxi, P. R. China, Xi'an, Shaanxi, 710061, CHINA
| | - Rong Lin
- Department of Pharmacology, Xi'an Jiaotong University Health Science Center, Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061,Shaanxi, P. R. China, Xi'an, 710061, CHINA
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3
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The Roles of Par3, Par6, and aPKC Polarity Proteins in Normal Neurodevelopment and in Neurodegenerative and Neuropsychiatric Disorders. J Neurosci 2022; 42:4774-4793. [PMID: 35705493 DOI: 10.1523/jneurosci.0059-22.2022] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 04/30/2022] [Accepted: 05/02/2022] [Indexed: 11/21/2022] Open
Abstract
Normal neural circuits and functions depend on proper neuronal differentiation, migration, synaptic plasticity, and maintenance. Abnormalities in these processes underlie various neurodevelopmental, neuropsychiatric, and neurodegenerative disorders. Neural development and maintenance are regulated by many proteins. Among them are Par3, Par6 (partitioning defective 3 and 6), and aPKC (atypical protein kinase C) families of evolutionarily conserved polarity proteins. These proteins perform versatile functions by forming tripartite or other combinations of protein complexes, which hereafter are collectively referred to as "Par complexes." In this review, we summarize the major findings on their biophysical and biochemical properties in cell polarization and signaling pathways. We next summarize their expression and localization in the nervous system as well as their versatile functions in various aspects of neurodevelopment, including neuroepithelial polarity, neurogenesis, neuronal migration, neurite differentiation, synaptic plasticity, and memory. These versatile functions rely on the fundamental roles of Par complexes in cell polarity in distinct cellular contexts. We also discuss how cell polarization may correlate with subcellular polarization in neurons. Finally, we review the involvement of Par complexes in neuropsychiatric and neurodegenerative disorders, such as schizophrenia and Alzheimer's disease. While emerging evidence indicates that Par complexes are essential for proper neural development and maintenance, many questions on their in vivo functions have yet to be answered. Thus, Par3, Par6, and aPKC continue to be important research topics to advance neuroscience.
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Wang LT, Proulx MÈ, Kim AD, Lelarge V, McCaffrey L. A proximity proteomics screen in three-dimensional spheroid cultures identifies novel regulators of lumen formation. Sci Rep 2021; 11:22807. [PMID: 34815476 PMCID: PMC8610992 DOI: 10.1038/s41598-021-02178-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 10/28/2021] [Indexed: 11/18/2022] Open
Abstract
Apical-basal cell polarity and lumen formation are essential features of many epithelial tissues, which are disrupted in diseases like cancer. Here, we describe a proteomics-based screen to identify proteins involved in lumen formation in three-dimensional spheroid cultures. We established a suspension-based culture method suitable for generating polarized cysts in sufficient quantities for proteomic analysis. Using this approach, we identified several known and unknown proteins proximally associated with PAR6B, an apical protein involved in lumen formation. Functional analyses of candidates identified PARD3B (a homolog of PARD3), RALB, and HRNR as regulators of lumen formation. We also identified PTPN14 as a component of the Par-complex that is required for fidelity of apical-basal polarity. Cells transformed with KRASG12V exhibit lumen collapse/filling concomitant with disruption of the Par-complex and down-regulation of PTPN14. Enforced expression of PTPN14 maintained the lumen and restricted the transformed phenotype in KRASG12V-expressing cells. This represents an applicable approach to explore protein–protein interactions in three-dimensional culture and to identify proteins important for lumen maintenance in normal and oncogene-expressing cells.
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Affiliation(s)
- Li-Ting Wang
- Rosalind and Morris Goodman Cancer Institute, McGill University, Montreal, QC, H3A 1A3, Canada.,Division of Experimental Medicine, McGill University, Montreal, QC, H4A 3J1, Canada
| | - Marie-Ève Proulx
- Rosalind and Morris Goodman Cancer Institute, McGill University, Montreal, QC, H3A 1A3, Canada.,Department of Biochemistry, McGill University, Montreal, QC, H3G 1Y6, Canada
| | - Anne D Kim
- Rosalind and Morris Goodman Cancer Institute, McGill University, Montreal, QC, H3A 1A3, Canada.,Division of Experimental Medicine, McGill University, Montreal, QC, H4A 3J1, Canada
| | - Virginie Lelarge
- Rosalind and Morris Goodman Cancer Institute, McGill University, Montreal, QC, H3A 1A3, Canada
| | - Luke McCaffrey
- Rosalind and Morris Goodman Cancer Institute, McGill University, Montreal, QC, H3A 1A3, Canada. .,Division of Experimental Medicine, McGill University, Montreal, QC, H4A 3J1, Canada. .,Department of Biochemistry, McGill University, Montreal, QC, H3G 1Y6, Canada. .,Gerald Bronfman Department of Oncology, McGill University, Montreal, QC, H4A 3T2, Canada.
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5
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CD13 orients the apical-basal polarity axis necessary for lumen formation. Nat Commun 2021; 12:4697. [PMID: 34349123 PMCID: PMC8338993 DOI: 10.1038/s41467-021-24993-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Accepted: 07/09/2021] [Indexed: 02/07/2023] Open
Abstract
Polarized epithelial cells can organize into complex structures with a characteristic central lumen. Lumen formation requires that cells coordinately orient their polarity axis so that the basolateral domain is on the outside and apical domain inside epithelial structures. Here we show that the transmembrane aminopeptidase, CD13, is a key determinant of epithelial polarity orientation. CD13 localizes to the apical membrane and associates with an apical complex with Par6. CD13-deficient cells display inverted polarity in which apical proteins are retained on the outer cell periphery and fail to accumulate at an intercellular apical initiation site. Here we show that CD13 is required to couple apical protein cargo to Rab11-endosomes and for capture of endosomes at the apical initiation site. This role in polarity utilizes the short intracellular domain but is independent of CD13 peptidase activity.
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6
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Dong W, Lu J, Zhang X, Wu Y, Lettieri K, Hammond GR, Hong Y. A polybasic domain in aPKC mediates Par6-dependent control of membrane targeting and kinase activity. J Cell Biol 2021; 219:151883. [PMID: 32580209 PMCID: PMC7337507 DOI: 10.1083/jcb.201903031] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 03/04/2020] [Accepted: 04/19/2020] [Indexed: 12/14/2022] Open
Abstract
Mechanisms coupling the atypical PKC (aPKC) kinase activity to its subcellular localization are essential for cell polarization. Unlike other members of the PKC family, aPKC has no well-defined plasma membrane (PM) or calcium binding domains, leading to the assumption that its subcellular localization relies exclusively on protein–protein interactions. Here we show that in both Drosophila and mammalian cells, the pseudosubstrate region (PSr) of aPKC acts as a polybasic domain capable of targeting aPKC to the PM via electrostatic binding to PM PI4P and PI(4,5)P2. However, physical interaction between aPKC and Par-6 is required for the PM-targeting of aPKC, likely by allosterically exposing the PSr to bind PM. Binding of Par-6 also inhibits aPKC kinase activity, and such inhibition can be relieved through Par-6 interaction with apical polarity protein Crumbs. Our data suggest a potential mechanism in which allosteric regulation of polybasic PSr by Par-6 couples the control of both aPKC subcellular localization and spatial activation of its kinase activity.
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Affiliation(s)
- Wei Dong
- Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, PA
| | - Juan Lu
- Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, PA
| | - Xuejing Zhang
- Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, PA
| | - Yan Wu
- Jiangsu University, Zhengjiang, Jiangsu, People's Republic of China
| | - Kaela Lettieri
- First Experience in Research Program, University of Pittsburgh, Pittsburgh, PA
| | - Gerald R Hammond
- Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, PA
| | - Yang Hong
- Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, PA
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7
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Martin E, Girardello R, Dittmar G, Ludwig A. New insights into the organization and regulation of the apical polarity network in mammalian epithelial cells. FEBS J 2021; 288:7073-7095. [DOI: 10.1111/febs.15710] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 01/05/2021] [Accepted: 01/11/2021] [Indexed: 12/11/2022]
Affiliation(s)
- Eleanor Martin
- School of Biological Sciences Nanyang Technological University Singapore City Singapore
- Proteomics of Cellular Signaling Luxembourg Institute of Health Strassen Luxembourg
| | - Rossana Girardello
- School of Biological Sciences Nanyang Technological University Singapore City Singapore
- Proteomics of Cellular Signaling Luxembourg Institute of Health Strassen Luxembourg
| | - Gunnar Dittmar
- Proteomics of Cellular Signaling Luxembourg Institute of Health Strassen Luxembourg
- Department of Life Sciences and Medicine University of Luxembourg Luxembourg
| | - Alexander Ludwig
- School of Biological Sciences Nanyang Technological University Singapore City Singapore
- NTU Institute of Structural Biology (NISB) Experimental Medicine Building Nanyang Technological University Singapore City Singapore
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8
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Chytła A, Gajdzik-Nowak W, Olszewska P, Biernatowska A, Sikorski AF, Czogalla A. Not Just Another Scaffolding Protein Family: The Multifaceted MPPs. Molecules 2020; 25:molecules25214954. [PMID: 33114686 PMCID: PMC7662862 DOI: 10.3390/molecules25214954] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/16/2020] [Accepted: 10/20/2020] [Indexed: 01/03/2023] Open
Abstract
Membrane palmitoylated proteins (MPPs) are a subfamily of a larger group of multidomain proteins, namely, membrane-associated guanylate kinases (MAGUKs). The ubiquitous expression and multidomain structure of MPPs provide the ability to form diverse protein complexes at the cell membranes, which are involved in a wide range of cellular processes, including establishing the proper cell structure, polarity and cell adhesion. The formation of MPP-dependent complexes in various cell types seems to be based on similar principles, but involves members of different protein groups, such as 4.1-ezrin-radixin-moesin (FERM) domain-containing proteins, polarity proteins or other MAGUKs, showing their multifaceted nature. In this review, we discuss the function of the MPP family in the formation of multiple protein complexes. Notably, we depict their significant role for cell physiology, as the loss of interactions between proteins involved in the complex has a variety of negative consequences. Moreover, based on recent studies concerning the mechanism of membrane raft formation, we shed new light on a possible role played by MPPs in lateral membrane organization.
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Affiliation(s)
- Agnieszka Chytła
- Department of Cytobiochemistry, Faculty of Biotechnology, University of Wroclaw, 50-383 Wroclaw, Poland; (A.C.); (W.G.-N.); (P.O.); (A.B.)
| | - Weronika Gajdzik-Nowak
- Department of Cytobiochemistry, Faculty of Biotechnology, University of Wroclaw, 50-383 Wroclaw, Poland; (A.C.); (W.G.-N.); (P.O.); (A.B.)
| | - Paulina Olszewska
- Department of Cytobiochemistry, Faculty of Biotechnology, University of Wroclaw, 50-383 Wroclaw, Poland; (A.C.); (W.G.-N.); (P.O.); (A.B.)
| | - Agnieszka Biernatowska
- Department of Cytobiochemistry, Faculty of Biotechnology, University of Wroclaw, 50-383 Wroclaw, Poland; (A.C.); (W.G.-N.); (P.O.); (A.B.)
| | - Aleksander F. Sikorski
- Research and Development Center, Regional Specialist Hospital, Kamieńskiego 73a, 51-154 Wroclaw, Poland;
| | - Aleksander Czogalla
- Department of Cytobiochemistry, Faculty of Biotechnology, University of Wroclaw, 50-383 Wroclaw, Poland; (A.C.); (W.G.-N.); (P.O.); (A.B.)
- Correspondence: ; Tel.: +48-71375-6356
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9
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Tiwari A, Swamynathan S, Jhanji V, Swamynathan SK. KLF4 Coordinates Corneal Epithelial Apical-Basal Polarity and Plane of Cell Division and Is Downregulated in Ocular Surface Squamous Neoplasia. Invest Ophthalmol Vis Sci 2020; 61:15. [PMID: 32396634 PMCID: PMC7409308 DOI: 10.1167/iovs.61.5.15] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Purpose Previously, we demonstrated that Krüppel-like factor 4 (KLF4) promotes corneal epithelial (CE) homeostasis by suppressing epithelial-mesenchymal transition (EMT) and TGF-β signaling. As TGF-β affects epithelial apicobasal polarity (ABP) and plane of division, we investigated the role of KLF4 in these processes. Methods Klf4 was ablated in adult ternary transgenic Klf4Δ/ΔCE (Klf4LoxP/LoxP/Krt12rtTA/rtTA/Tet-O-Cre) mouse CE using doxycycline chow. ABP and plane of division markers’ expression in Klf4Δ/ΔCE and human ocular surface squamous neoplasia (OSSN) tissues relative to controls was evaluated by quantitative PCR, immunoblots, and/or immunofluorescent staining. Results Klf4Δ/ΔCE CE cells displayed downregulation of apical Pals1 and Crumbs1, apicolateral Par3, and basolateral Scribble, as well as upregulation of Rho family GTPase Cdc42, suggesting disruption of ABP. Phalloidin staining revealed that the Klf4Δ/ΔCE CE actin cytoskeleton is disrupted. Klf4Δ/ΔCE cells favored vertical plane of division within 67.5° to 90° of the CE basement membrane (39% and 47% of the dividing cells relative to 23% and 26% in the control based on phospho-histone-H3 and survivin, respectively), resulting in more dividing cells within the Klf4Δ/ΔCE CE as reported previously. KLF4 was downregulated in human OSSN tissues that displayed EMT and downregulation of PAR3, PALS1, and SCRIB, consistent with a protective role for KLF4. Conclusions By demonstrating that Klf4 ablation affects CE expression of ABP markers and Cdc42, cytoskeletal actin organization, and the plane of cell division and that KLF4 is downregulated in OSSN tissues that display EMT and lack ABP, these results elucidate the key integrative role of KLF4 in coordinating CE cell polarity and plane of division, loss of which results in OSSN.
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10
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The Mammalian Crumbs Complex Defines a Distinct Polarity Domain Apical of Epithelial Tight Junctions. Curr Biol 2020; 30:2791-2804.e6. [PMID: 32531288 DOI: 10.1016/j.cub.2020.05.032] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 03/26/2020] [Accepted: 05/07/2020] [Indexed: 12/28/2022]
Abstract
Epithelial apico-basal polarity is established through the asymmetric cortical distribution of the Par, Crumbs and Scribble polarity modules. Apical (Par and Crumbs) and basolateral (Scribble) polarity modules overlap at the apical-lateral border, which, in mammals, is defined by the apical junctional complex (AJC). The AJC is composed of tight junctions (TJ) and adherens junctions (AJ) and plays fundamental roles in epithelial morphogenesis and plasticity. However, the molecular composition and precise sub-junctional organization of the AJC and its associated polarity regulators are not well defined. Here, we used the peroxidase APEX2 for quantitative proximity proteomics (QPP) and electron microscopy (EM) imaging to dissect the architecture of the AJC in fully polarized MDCK-II cells. We present a high-confidence proteome of the apical-lateral border in which TJ and AJ components and apical and lateral compartment markers are spatially resolved. We further demonstrate that the Crumbs complex (Pals1, PatJ, Lin7c, and Crumbs3) defines a hitherto unidentified membrane compartment apical of TJ, which we coin the vertebrate marginal zone (VMZ). QPP, imaging, and immunoprecipitation assays showed that the HOMER scaffolding proteins, PKN2 and PTPN13, and the membrane-proximal HIPPO pathway proteins ARHGAP29 and STXBP4 are recruited to the VMZ via the PDZ domains of PatJ. Taken together, our work defines the spatial and molecular organization of the apical-lateral border in mammalian epithelial cells, reveals an intriguing molecular and spatial conservation of invertebrate and vertebrate cell polarity protein domains, and identifies a VMZ-associated protein network implicated in HIPPO signaling and the control of the cortical actin cytoskeleton.
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11
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Krahn MP. Phospholipids of the Plasma Membrane - Regulators or Consequence of Cell Polarity? Front Cell Dev Biol 2020; 8:277. [PMID: 32411703 PMCID: PMC7198698 DOI: 10.3389/fcell.2020.00277] [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: 01/30/2020] [Accepted: 03/31/2020] [Indexed: 12/15/2022] Open
Abstract
Cell polarity is a key feature of many eukaryotic cells, including neurons, epithelia, endothelia and asymmetrically dividing stem cells. Apart from the specific localization of proteins to distinct domains of the plasma membrane, most of these cells exhibit an asymmetric distribution of phospholipids within the plasma membrane too. Notably, research over the last years has revealed that many known conserved regulators of apical-basal polarity in epithelial cells are capable of binding to phospholipids, which in turn regulate the localization and to some extent the function of these proteins. Conversely, phospholipid-modifying enzymes are recruited and controlled by polarity regulators, demonstrating an elaborated balance between asymmetrically localized proteins and phospholipids, which are enriched in certain (micro)domains of the plasma membrane. In this review, we will focus on our current understanding of apical-basal polarity and the implication of phospholipids within the plasma membrane during the cell polarization of epithelia and migrating cells.
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Affiliation(s)
- Michael P Krahn
- Department of Medical Cell Biology, Medical Clinic D, University Hospital of Münster, Münster, Germany
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12
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Nunes de Almeida F, Walther RF, Pressé MT, Vlassaks E, Pichaud F. Cdc42 defines apical identity and regulates epithelial morphogenesis by promoting apical recruitment of Par6-aPKC and Crumbs. Development 2019; 146:dev175497. [PMID: 31405903 PMCID: PMC6703713 DOI: 10.1242/dev.175497] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 07/10/2019] [Indexed: 01/20/2023]
Abstract
Cdc42 regulates epithelial morphogenesis together with the Par complex (Baz/Par3-Par6-aPKC), Crumbs (Crb/CRB3) and Stardust (Sdt/PALS1). However, how these proteins work together and interact during epithelial morphogenesis is not well understood. To address this issue, we used the genetically amenable Drosophila pupal photoreceptor and follicular epithelium. We show that during epithelial morphogenesis active Cdc42 accumulates at the developing apical membrane and cell-cell contacts, independently of the Par complex and Crb. However, membrane localization of Baz, Par6-aPKC and Crb all depend on Cdc42. We find that although binding of Cdc42 to Par6 is not essential for the recruitment of Par6 and aPKC to the membrane, it is required for their apical localization and accumulation, which we find also depends on Par6 retention by Crb. In the pupal photoreceptor, membrane recruitment of Par6-aPKC also depends on Baz. Our work shows that Cdc42 is required for this recruitment and suggests that this factor promotes the handover of Par6-aPKC from Baz onto Crb. Altogether, we propose that Cdc42 drives morphogenesis by conferring apical identity, Par-complex assembly and apical accumulation of Crb.
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Affiliation(s)
| | - Rhian F Walther
- MRC - Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK
| | - Mary T Pressé
- MRC - Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK
| | - Evi Vlassaks
- MRC - Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK
| | - Franck Pichaud
- MRC - Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK
- Institute for the Physics of Living Systems, University College London, London WC1E 6BT, UK
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13
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Snigdha K, Gangwani KS, Lapalikar GV, Singh A, Kango-Singh M. Hippo Signaling in Cancer: Lessons From Drosophila Models. Front Cell Dev Biol 2019; 7:85. [PMID: 31231648 PMCID: PMC6558396 DOI: 10.3389/fcell.2019.00085] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 05/03/2019] [Indexed: 12/19/2022] Open
Abstract
Hippo pathway was initially identified through genetic screens for genes regulating organ size in fruitflies. Recent studies have highlighted the role of Hippo signaling as a key regulator of homeostasis, and in tumorigenesis. Hippo pathway is comprised of genes that act as tumor suppressor genes like hippo (hpo) and warts (wts), and oncogenes like yorkie (yki). YAP and TAZ are two related mammalian homologs of Drosophila Yki that act as effectors of the Hippo pathway. Hippo signaling deficiency can cause YAP- or TAZ-dependent oncogene addiction for cancer cells. YAP and TAZ are often activated in human malignant cancers. These transcriptional regulators may initiate tumorigenic changes in solid tumors by inducing cancer stem cells and proliferation, culminating in metastasis and chemo-resistance. Given the complex mechanisms (e.g., of the cancer microenvironment, and the extrinsic and intrinsic cues) that overpower YAP/TAZ inhibition, the molecular roles of the Hippo pathway in tumor growth and progression remain poorly defined. Here we review recent findings from studies in whole animal model organism like Drosophila on the role of Hippo signaling regarding its connection to inflammation, tumor microenvironment, and other oncogenic signaling in cancer growth and progression.
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Affiliation(s)
- Kirti Snigdha
- Department of Biology, University of Dayton, Dayton, OH, United States
| | | | - Gauri Vijay Lapalikar
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, United States
| | - Amit Singh
- Department of Biology, University of Dayton, Dayton, OH, United States.,Pre-Medical Programs, University of Dayton, Dayton, OH, United States.,Center for Tissue Regeneration and Engineering at Dayton, University of Dayton, Dayton, OH, United States.,Integrated Science and Engineering Center, University of Dayton, Dayton, OH, United States
| | - Madhuri Kango-Singh
- Department of Biology, University of Dayton, Dayton, OH, United States.,Pre-Medical Programs, University of Dayton, Dayton, OH, United States.,Center for Tissue Regeneration and Engineering at Dayton, University of Dayton, Dayton, OH, United States.,Integrated Science and Engineering Center, University of Dayton, Dayton, OH, United States
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14
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Pichaud F, Walther RF, Nunes de Almeida F. Regulation of Cdc42 and its effectors in epithelial morphogenesis. J Cell Sci 2019; 132:132/10/jcs217869. [PMID: 31113848 DOI: 10.1242/jcs.217869] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cdc42 - a member of the small Rho GTPase family - regulates cell polarity across organisms from yeast to humans. It is an essential regulator of polarized morphogenesis in epithelial cells, through coordination of apical membrane morphogenesis, lumen formation and junction maturation. In parallel, work in yeast and Caenorhabditis elegans has provided important clues as to how this molecular switch can generate and regulate polarity through localized activation or inhibition, and cytoskeleton regulation. Recent studies have revealed how important and complex these regulations can be during epithelial morphogenesis. This complexity is mirrored by the fact that Cdc42 can exert its function through many effector proteins. In epithelial cells, these include atypical PKC (aPKC, also known as PKC-3), the P21-activated kinase (PAK) family, myotonic dystrophy-related Cdc42 binding kinase beta (MRCKβ, also known as CDC42BPB) and neural Wiskott-Aldrich syndrome protein (N-WASp, also known as WASL). Here, we review how the spatial regulation of Cdc42 promotes polarity and polarized morphogenesis of the plasma membrane, with a focus on the epithelial cell type.
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Affiliation(s)
- Franck Pichaud
- MRC - Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK .,Institute for the Physics of Living Systems, University College London, London WC1E 6BT, UK
| | - Rhian F Walther
- MRC - Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK
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15
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Renschler FA, Bruekner SR, Salomon PL, Mukherjee A, Kullmann L, Schütz-Stoffregen MC, Henzler C, Pawson T, Krahn MP, Wiesner S. Structural basis for the interaction between the cell polarity proteins Par3 and Par6. Sci Signal 2018; 11:11/517/eaam9899. [PMID: 29440511 DOI: 10.1126/scisignal.aam9899] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Polarity is a fundamental property of most cell types. The Par protein complex is a major driving force in generating asymmetrically localized protein networks and consists of atypical protein kinase C (aPKC), Par3, and Par6. Dysfunction of this complex causes developmental abnormalities and diseases such as cancer. We identified a PDZ domain-binding motif in Par6 that was essential for its interaction with Par3 in vitro and for Par3-mediated membrane localization of Par6 in cultured cells. In fly embryos, we observed that the PDZ domain-binding motif was functionally redundant with the PDZ domain in targeting Par6 to the cortex of epithelial cells. Our structural analyses by x-ray crystallography and NMR spectroscopy showed that both the PDZ1 and PDZ3 domains but not the PDZ2 domain in Par3 engaged in a canonical interaction with the PDZ domain-binding motif in Par6. Par3 thus has the potential to recruit two Par6 proteins simultaneously, which may facilitate the assembly of polarity protein networks through multivalent PDZ domain interactions.
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Affiliation(s)
- Fabian A Renschler
- Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, 72076 Tübingen, Germany
| | - Susanne R Bruekner
- Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, 72076 Tübingen, Germany
| | - Paulin L Salomon
- Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, 72076 Tübingen, Germany
| | - Amrita Mukherjee
- Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, 72076 Tübingen, Germany
| | - Lars Kullmann
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | | | - Christine Henzler
- Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, 72076 Tübingen, Germany
| | - Tony Pawson
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario M5G 1X5, Canada
| | - Michael P Krahn
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany.,Medical Clinic D, University Hospital of Münster, Domagkstraβe 3a, 48149 Münster, Germany
| | - Silke Wiesner
- Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, 72076 Tübingen, Germany.
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16
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Hochapfel F, Denk L, Mendl G, Schulze U, Maaßen C, Zaytseva Y, Pavenstädt H, Weide T, Rachel R, Witzgall R, Krahn MP. Distinct functions of Crumbs regulating slit diaphragms and endocytosis in Drosophila nephrocytes. Cell Mol Life Sci 2017; 74:4573-4586. [PMID: 28717874 PMCID: PMC11107785 DOI: 10.1007/s00018-017-2593-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 06/26/2017] [Accepted: 07/13/2017] [Indexed: 10/19/2022]
Abstract
Mammalian podocytes, the key determinants of the kidney's filtration barrier, differentiate from columnar epithelial cells and several key determinants of apical-basal polarity in the conventional epithelia have been shown to regulate podocyte morphogenesis and function. However, little is known about the role of Crumbs, a conserved polarity regulator in many epithelia, for slit-diaphragm formation and podocyte function. In this study, we used Drosophila nephrocytes as model system for mammalian podocytes and identified a conserved function of Crumbs proteins for cellular morphogenesis, nephrocyte diaphragm assembly/maintenance, and endocytosis. Nephrocyte-specific knock-down of Crumbs results in disturbed nephrocyte diaphragm assembly/maintenance and decreased endocytosis, which can be rescued by Drosophila Crumbs as well as human Crumbs2 and Crumbs3, which were both expressed in human podocytes. In contrast to the extracellular domain, which facilitates nephrocyte diaphragm assembly/maintenance, the intracellular FERM-interaction motif of Crumbs is essential for regulating endocytosis. Moreover, Moesin, which binds to the FERM-binding domain of Crumbs, is essential for efficient endocytosis. Thus, we describe here a new mechanism of nephrocyte development and function, which is likely to be conserved in mammalian podocytes.
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Affiliation(s)
- Florian Hochapfel
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
- Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Domagkstr. 3a, 48149, Münster, Germany
| | - Lucia Denk
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Gudrun Mendl
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Ulf Schulze
- Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Domagkstr. 3a, 48149, Münster, Germany
| | - Christine Maaßen
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Yulia Zaytseva
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Hermann Pavenstädt
- Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Domagkstr. 3a, 48149, Münster, Germany
| | - Thomas Weide
- Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Domagkstr. 3a, 48149, Münster, Germany
| | - Reinhard Rachel
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Ralph Witzgall
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Michael P Krahn
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany.
- Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Domagkstr. 3a, 48149, Münster, Germany.
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17
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Das S, Knust E. Stardust, the Janus-faced partner of Crumbs. J Cell Biol 2017; 216:1219-1221. [PMID: 28416478 PMCID: PMC5412578 DOI: 10.1083/jcb.201704023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The Drosophila melanogaster scaffolding protein Stardust (Sdt) stabilizes the transmembrane protein Crumbs, a conserved regulator of apical-basal epithelial polarity. In this issue, Perez-Mockus et al. (2017. J. Cell Biol https://doi.org/10.1083/jcb.201611196) report that a subset of Sdt isoforms are targeted by the ubiquitin ligase Neuralized, thus fine tuning the endocytosis and activity of this apical determinant.
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Affiliation(s)
- Shradha Das
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Elisabeth Knust
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
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18
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Koch L, Feicht S, Sun R, Sen A, Krahn MP. Domain-specific functions of Stardust in Drosophila embryonic development. ROYAL SOCIETY OPEN SCIENCE 2016; 3:160776. [PMID: 28018665 PMCID: PMC5180163 DOI: 10.1098/rsos.160776] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 10/19/2016] [Indexed: 06/06/2023]
Abstract
In Drosophila, the adaptor protein Stardust is essential for the stabilization of the polarity determinant Crumbs in various epithelial tissues, including the embryonic epidermis, the follicular epithelium and photoreceptor cells of the compound eye. In turn, Stardust recruits another adaptor protein, PATJ, to the subapical region to support adherens junction formation and morphogenetic events. Moreover, Stardust binds to Lin-7, which is dispensable in epithelial cells but functions in postsynaptic vesicle fusion. Finally, Stardust has been reported to bind directly to PAR-6, thereby linking the Crumbs-Stardust-PATJ complex to the PAR-6/aPKC complex. PAR-6 and aPKC are also capable of directly binding Bazooka (the Drosophila homologue of PAR-3) to form the PAR/aPKC complex, which is essential for apical-basal polarity and cell-cell contact formation in most epithelia. However, little is known about the physiological relevance of these interactions in the embryonic epidermis of Drosophila in vivo. Thus, we performed a structure-function analysis of the annotated domains with GFP-tagged Stardust and evaluated the localization and function of the mutant proteins in epithelial cells of the embryonic epidermis. The data presented here confirm a crucial role of the PDZ domain in binding Crumbs and recruiting the protein to the subapical region. However, the isolated PDZ domain is not capable of being recruited to the cortex, and the SH3 domain is essential to support the binding to Crumbs. Notably, the conserved N-terminal regions (ECR1 and ECR2) are not crucial for epithelial polarity. Finally, the GUK domain plays an important role for the protein's function, which is not directly linked to Crumbs stabilization, and the L27N domain is essential for epithelial polarization independently of recruiting PATJ.
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Affiliation(s)
| | | | | | | | - Michael P. Krahn
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053 Regensburg, Germany
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19
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Brinkmann BF, Steinbacher T, Hartmann C, Kummer D, Pajonczyk D, Mirzapourshafiyi F, Nakayama M, Weide T, Gerke V, Ebnet K. VE-cadherin interacts with cell polarity protein Pals1 to regulate vascular lumen formation. Mol Biol Cell 2016; 27:2811-21. [PMID: 27466317 PMCID: PMC5025268 DOI: 10.1091/mbc.e16-02-0127] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 07/19/2016] [Indexed: 02/06/2023] Open
Abstract
Blood vessel tubulogenesis requires the establishment of apicobasal polarity of endothelial cells. A novel interaction is described of the cell adhesion molecule VE-cadherin with the cell polarity protein Pals1. The activity of VE-cadherin in regulation of endothelial lumen formation depends on its interaction with both Pals1 and Par3. Blood vessel tubulogenesis requires the formation of stable cell-to-cell contacts and the establishment of apicobasal polarity of vascular endothelial cells. Cell polarity is regulated by highly conserved cell polarity protein complexes such as the Par3-aPKC-Par6 complex and the CRB3-Pals1-PATJ complex, which are expressed by many different cell types and regulate various aspects of cell polarity. Here we describe a functional interaction of VE-cadherin with the cell polarity protein Pals1. Pals1 directly interacts with VE-cadherin through a membrane-proximal motif in the cytoplasmic domain of VE-cadherin. VE-cadherin clusters Pals1 at cell–cell junctions. Mutating the Pals1-binding motif in VE-cadherin abrogates the ability of VE-cadherin to regulate apicobasal polarity and vascular lumen formation. In a similar way, deletion of the Par3-binding motif at the C-terminus of VE-cadherin impairs apicobasal polarity and vascular lumen formation. Our findings indicate that the biological activity of VE-cadherin in regulating endothelial polarity and vascular lumen formation is mediated through its interaction with the two cell polarity proteins Pals1 and Par3.
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Affiliation(s)
- Benjamin F Brinkmann
- Institute-Associated Research Group "Cell Adhesion and Cell Polarity,", University of Münster, 48419 Münster, Germany Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, University of Münster, 48419 Münster, Germany Interdisciplinary Clinical Research Center, University of Münster, 48419 Münster, Germany
| | - Tim Steinbacher
- Institute-Associated Research Group "Cell Adhesion and Cell Polarity,", University of Münster, 48419 Münster, Germany Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, University of Münster, 48419 Münster, Germany
| | - Christian Hartmann
- Institute-Associated Research Group "Cell Adhesion and Cell Polarity,", University of Münster, 48419 Münster, Germany Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, University of Münster, 48419 Münster, Germany Interdisciplinary Clinical Research Center, University of Münster, 48419 Münster, Germany
| | - Daniel Kummer
- Institute-Associated Research Group "Cell Adhesion and Cell Polarity,", University of Münster, 48419 Münster, Germany Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, University of Münster, 48419 Münster, Germany Interdisciplinary Clinical Research Center, University of Münster, 48419 Münster, Germany
| | - Denise Pajonczyk
- Institute-Associated Research Group "Cell Adhesion and Cell Polarity,", University of Münster, 48419 Münster, Germany Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, University of Münster, 48419 Münster, Germany
| | - Fatemeh Mirzapourshafiyi
- Laboratory for Cell Polarity and Organogenesis, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Masanori Nakayama
- Laboratory for Cell Polarity and Organogenesis, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Thomas Weide
- Department of Internal Medicine D, Division of Molecular Nephrology, University Hospital Münster, Albert-Schweitzer-Campus 1, University of Münster, 48419 Münster, Germany
| | - Volker Gerke
- Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, University of Münster, 48419 Münster, Germany Cells-in-Motion Cluster of Excellence (EXC 1003-CiM), University of Münster, 48419 Münster, Germany
| | - Klaus Ebnet
- Institute-Associated Research Group "Cell Adhesion and Cell Polarity,", University of Münster, 48419 Münster, Germany Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, University of Münster, 48419 Münster, Germany Interdisciplinary Clinical Research Center, University of Münster, 48419 Münster, Germany
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20
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Whitney DS, Peterson FC, Kittell AW, Egner JM, Prehoda KE, Volkman BF. Correction to Binding of Crumbs to the Par-6 CRIB-PDZ Module Is Regulated by Cdc42. Biochemistry 2016; 55:2063. [PMID: 27012924 DOI: 10.1021/acs.biochem.6b00254] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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21
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Whitney DS, Peterson FC, Kittell AW, Egner JM, Prehoda KE, Volkman BF. Binding of Crumbs to the Par-6 CRIB-PDZ Module Is Regulated by Cdc42. Biochemistry 2016; 55:1455-61. [PMID: 26894406 PMCID: PMC5433836 DOI: 10.1021/acs.biochem.5b01342] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Par-6 is a scaffold protein that organizes other proteins into a complex required to initiate and maintain cell polarity. Cdc42-GTP binds the CRIB module of Par-6 and alters the binding affinity of the adjoining PDZ domain. Allosteric regulation of the Par-6 PDZ domain was first demonstrated using a peptide identified in a screen of typical carboxyl-terminal ligands. Crumbs, a membrane protein that localizes a conserved polarity complex, was subsequently identified as a functional partner for Par-6 that likely interacts with the PDZ domain. Here we show by nuclear magnetic resonance that Par-6 binds a Crumbs carboxyl-terminal peptide and report the crystal structure of the PDZ-peptide complex. The Crumbs peptide binds Par-6 more tightly than the previously studied carboxyl peptide ligand and interacts with the CRIB-PDZ module in a Cdc42-dependent manner. The Crumbs:Par-6 crystal structure reveals specific PDZ-peptide contacts that contribute to its higher affinity and Cdc42-enhanced binding. Comparisons with existing structures suggest that multiple C-terminal Par-6 ligands respond to a common conformational switch that transmits the allosteric effects of GTPase binding.
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Affiliation(s)
- Dustin S. Whitney
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Francis C. Peterson
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Aaron W. Kittell
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226
| | - John M. Egner
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Kenneth E. Prehoda
- Department of Chemistry and Biochemistry and Institute for Molecular Biology, University of Oregon, Eugene, OR, 97403
| | - Brian F. Volkman
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226,To whom correspondence should be addressed: ; 414-955-8400
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22
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Charrier LE, Loie E, Laprise P. Mouse Crumbs3 sustains epithelial tissue morphogenesis in vivo. Sci Rep 2015; 5:17699. [PMID: 26631503 PMCID: PMC4668553 DOI: 10.1038/srep17699] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 11/03/2015] [Indexed: 02/07/2023] Open
Abstract
The human apical protein CRB3 (Crb3 in mouse) organizes epithelial cell polarity. Loss of CRB3 expression increases the tumorogenic potential of cultured epithelial cells and favors metastasis formation in nude mice. These data emphasize the need of in vivo models to study CRB3 functions. Here, we report the phenotypic analysis of a novel Crb3 knockout mouse model. Crb3-deficient newborn mice show improper clearance of airways, suffer from respiratory distress and display perinatal lethality. Crb3 is also essential to maintain apical membrane identity in kidney epithelial cells. Numerous kidney cysts accompany these polarity defects. Impaired differentiation of the apical membrane is also observed in a subset of cells of the intestinal epithelium. This results in improper remodeling of adhesive contacts in the developing intestinal epithelium, thereby leading to villus fusion. We also noted a strong increase in cytoplasmic β-catenin levels in intestinal epithelial cells. β-catenin is a mediator of the Wnt signaling pathway, which is overactivated in the majority of colon cancers. In addition to clarifying the physiologic roles of Crb3, our study highlights that further functional analysis of this protein is likely to provide insights into the etiology of diverse pathologies, including respiratory distress syndrome, polycystic kidney disease and cancer.
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Affiliation(s)
- Lucie E. Charrier
- Département de Biologie Moléculaire, Biochimie Médicale et Pathologie/Centre de Recherche sur le Cancer, Université Laval, Québec, Canada
- CRCHU de Québec-axe oncologie, Québec, Canada
| | - Elise Loie
- Département de Biologie Moléculaire, Biochimie Médicale et Pathologie/Centre de Recherche sur le Cancer, Université Laval, Québec, Canada
- CRCHU de Québec-axe oncologie, Québec, Canada
| | - Patrick Laprise
- Département de Biologie Moléculaire, Biochimie Médicale et Pathologie/Centre de Recherche sur le Cancer, Université Laval, Québec, Canada
- CRCHU de Québec-axe oncologie, Québec, Canada
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23
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Sen A, Sun R, Krahn MP. Localization and Function of Pals1-associated Tight Junction Protein in Drosophila Is Regulated by Two Distinct Apical Complexes. J Biol Chem 2015; 290:13224-33. [PMID: 25847234 DOI: 10.1074/jbc.m114.629014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Indexed: 11/06/2022] Open
Abstract
The transmembrane protein Crumbs (Crb) and its intracellular adaptor protein Pals1 (Stardust, Sdt in Drosophila) play a crucial role in the establishment and maintenance of apical-basal polarity in epithelial cells in various organisms. In contrast, the multiple PDZ domain-containing protein Pals1-associated tight junction protein (PATJ), which has been described to form a complex with Crb/Sdt, is not essential for apical basal polarity or for the stability of the Crb/Sdt complex in the Drosophila epidermis. Here we show that, in the embryonic epidermis, Sdt is essential for the correct subcellular localization of PATJ in differentiated epithelial cells but not during cellularization. Consistently, the L27 domain of PATJ is crucial for the correct localization and function of the protein. Our data further indicate that the four PDZ domains of PATJ function, to a large extent, in redundancy, regulating the function of the protein. Interestingly, the PATJ-Sdt heterodimer is not only recruited to the apical cell-cell contacts by binding to Crb but depends on functional Bazooka (Baz). However, biochemical experiments show that PATJ associates with both complexes, the Baz-Sdt and the Crb-Sdt complex, in the mature epithelium of the embryonic epidermis, suggesting a role of these two complexes for the function of PATJ during the development of Drosophila.
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Affiliation(s)
- Arnab Sen
- From the Institute of Molecular and Cellular Anatomy, University of Regensburg, 93053 Regensburg, Germany
| | - Rui Sun
- From the Institute of Molecular and Cellular Anatomy, University of Regensburg, 93053 Regensburg, Germany
| | - Michael P Krahn
- From the Institute of Molecular and Cellular Anatomy, University of Regensburg, 93053 Regensburg, Germany
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24
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Zhu H, Liu Z, Huang Y, Zhang C, Li G, Liu W. Biochemical and structural characterization of MUPP1-PDZ4 domain from Mus musculus. Acta Biochim Biophys Sin (Shanghai) 2015; 47:199-206. [PMID: 25662616 DOI: 10.1093/abbs/gmv002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Specific protein-protein interactions are important for biological signal transduction. The postsynaptic density-95, disc-large, and zonulin-1 (PDZ) domain is one of the most abundant protein interaction modules. Multi-PDZ-domain protein 1 (MUPP1), as a scaffold protein, contains 13 PDZ domains and plays an important role in cytoskeletal organization, cell polarity, and cell proliferation. The study on PDZ domain of MUPP1 helps to understand the mechanisms and functions of MUPP1. In the present study, the fourth PDZ domain of MUPP1 (MUPP1-PDZ4) from Mus musculus was cloned, expressed, purified, and characterized. The MUPP1-PDZ4 domain was subcloned into a pET-vector and expressed in Escherichia coli. Affinity chromatography and size-exclusion chromatography were used to purify the protein. MUPP1-PDZ4 protein was a monomer with a molar mass of 16.4 kDa in solution and had a melting point of 60.3°C. Using the sitting-drop vapor-diffusion method, MUPP1-PDZ4 protein crystals were obtained in a solution (pH 7.0) containing 2% (v/v) polyethylene glycol 400, 0.1 M imidazole, and 24% (w/v) polyethylene glycol monoethyl ether 5000. Finally, the crystal was diffracted with 1.6 Å resolution. The crystal structure showed that MUPP1-PDZ4 domain contained three α-helices and six β-strands in the core. The GLGI motif, L562/A564 on the β-strand B, and H605/V608/L612 on the α-helix B formed a PDZ binding pocket which could bind to the C-terminal of the binding partners. This biochemical and structural information will provide insights into how PDZ binds to its target peptide and the theoretical foundation for the function of MUPP1.
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Affiliation(s)
- Haili Zhu
- Shenzhen Key Laboratory for Neuronal Structural Biology, Biomedical Research Institute, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Shenzhen 518036, China
| | - Zexu Liu
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China
| | - Yuxin Huang
- Shenzhen Key Laboratory for Neuronal Structural Biology, Biomedical Research Institute, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Shenzhen 518036, China
| | - Chao Zhang
- Shenzhen Key Laboratory for Neuronal Structural Biology, Biomedical Research Institute, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Shenzhen 518036, China
| | - Gang Li
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Wei Liu
- Shenzhen Key Laboratory for Neuronal Structural Biology, Biomedical Research Institute, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Shenzhen 518036, China Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China
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25
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Ngok SP, Lin WH, Anastasiadis PZ. Establishment of epithelial polarity--GEF who's minding the GAP? J Cell Sci 2014; 127:3205-15. [PMID: 24994932 DOI: 10.1242/jcs.153197] [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
Cell polarization is a fundamental process that underlies epithelial morphogenesis, cell motility, cell division and organogenesis. Loss of polarity predisposes tissues to developmental disorders and contributes to cancer progression. The formation and establishment of epithelial cell polarity is mediated by the cooperation of polarity protein complexes, namely the Crumbs, partitioning defective (Par) and Scribble complexes, with Rho family GTPases, including RhoA, Rac1 and Cdc42. The activation of different GTPases triggers distinct downstream signaling pathways to modulate protein-protein interactions and cytoskeletal remodeling. The spatio-temporal activation and inactivation of these small GTPases is tightly controlled by a complex interconnected network of different regulatory proteins, including guanine-nucleotide-exchange factors (GEFs), GTPase-activating proteins (GAPs), and guanine-nucleotide-dissociation inhibitors (GDIs). In this Commentary, we focus on current understanding on how polarity complexes interact with GEFs and GAPs to control the precise location and activation of Rho GTPases (Crumbs for RhoA, Par for Rac1, and Scribble for Cdc42) to promote apical-basal polarization in mammalian epithelial cells. The mutual exclusion of GTPase activities, especially that of RhoA and Rac1, which is well established, provides a mechanism through which polarity complexes that act through distinct Rho GTPases function as cellular rheostats to fine-tune specific downstream pathways to differentiate and preserve the apical and basolateral domains. This article is part of a Minifocus on Establishing polarity.
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Affiliation(s)
- Siu P Ngok
- Department of Cancer Biology, Mayo Clinic Comprehensive Cancer Center, Griffin Cancer Research Building, Room 307, 4500 San Pablo Road, Jacksonville, FL 32224, USA
| | - Wan-Hsin Lin
- Department of Cancer Biology, Mayo Clinic Comprehensive Cancer Center, Griffin Cancer Research Building, Room 307, 4500 San Pablo Road, Jacksonville, FL 32224, USA
| | - Panos Z Anastasiadis
- Department of Cancer Biology, Mayo Clinic Comprehensive Cancer Center, Griffin Cancer Research Building, Room 307, 4500 San Pablo Road, Jacksonville, FL 32224, USA
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26
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Alves CH, Pellissier LP, Wijnholds J. The CRB1 and adherens junction complex proteins in retinal development and maintenance. Prog Retin Eye Res 2014; 40:35-52. [PMID: 24508727 DOI: 10.1016/j.preteyeres.2014.01.001] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 01/21/2014] [Accepted: 01/27/2014] [Indexed: 12/30/2022]
Abstract
The early developing retinal neuroepithelium is composed of multipotent retinal progenitor cells that differentiate in a time specific manner, giving rise to six major types of neuronal and one type of glial cells. These cells migrate and organize in three distinct nuclear layers divided by two plexiform layers. Apical and adherens junction complexes have a crucial role in this process by the establishment of polarity and adhesion. Changes in these complexes disturb the spatiotemporal aspects of retinogenesis, leading to retinal degeneration resulting in mild or severe impairment of retinal function and vision. In this review, we summarize the mouse models for the different members of the apical and adherens junction protein complexes and describe the main features of their retinal phenotypes. The knowledge acquired from the different mutant animals for these proteins corroborate their importance in retina development and maintenance of normal retinal structure and function. More recently, several studies have tried to unravel the connection between the apical proteins, important cellular signaling pathways and their relation in retina development. Still, the mechanisms by which these proteins function remain largely unknown. Here, we hypothesize how the mammalian apical CRB1 complex might control retinogenesis and prevents onset of Leber congenital amaurosis or retinitis pigmentosa.
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Affiliation(s)
- Celso Henrique Alves
- Department of Neuromedical Genetics, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences (KNAW), Meibergdreef 47, 1105 BA Amsterdam, The Netherlands
| | - Lucie P Pellissier
- Department of Neuromedical Genetics, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences (KNAW), Meibergdreef 47, 1105 BA Amsterdam, The Netherlands
| | - Jan Wijnholds
- Department of Neuromedical Genetics, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences (KNAW), Meibergdreef 47, 1105 BA Amsterdam, The Netherlands.
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27
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Yuan J, Zhu Q, Liu B. Phylogenetic and biological significance of evolutionary elements from metazoan mitochondrial genomes. PLoS One 2014; 9:e84330. [PMID: 24465405 PMCID: PMC3896360 DOI: 10.1371/journal.pone.0084330] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 11/14/2013] [Indexed: 12/29/2022] Open
Abstract
The evolutionary history of living species is usually inferred through the phylogenetic analysis of molecular and morphological information using various mathematical models. New challenges in phylogenetic analysis are centered mostly on the search for accurate and efficient methods to handle the huge amounts of sequence data generated from newer genome sequencing. The next major challenge is the determination of relationships between the evolution of structural elements and their functional implementation, which is largely ignored in previous analyses. Here, we described the discovery of structural elements in metazoan mitochondrial genomes, termed key K-strings, that can serve as a basis for phylogenetic tree construction. Although comprising only a small fraction (0.73%) of all K-strings, these key K-strings are pivotal to the tree construction because they allow for a significant reduction in the computational time required to construct phylogenetic trees, and more importantly, they make significant improvement to the results of phylogenetic inference. The trees constructed from the key K-strings were consistent overall to our current view of metazoan phylogeny and exhibited a more rational topology than the trees constructed by using other conventional methods. Surprisingly, the key K-strings tended to accumulate in the conserved regions of the original sequences, which were most likely due to strong selection pressure. Furthermore, the special structural features of the key K-strings should have some potential applications in the study of the structures and functions relationship of proteins and in the determination of evolutionary trajectory of species. The novelty and potential importance of key K-strings lead us to believe that they are essential evolutionary elements. As such, they may play important roles in the process of species evolution and their physical existence. Further studies could lead to discoveries regarding the relationship between evolution and processes of speciation.
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Affiliation(s)
- Jianbo Yuan
- Center of Systematic Genomics, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, Xinjiang, China
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, Shandong, China
- Graduate University of Chinese Academy of Sciences, Beijing, China
| | | | - Bin Liu
- Center of Systematic Genomics, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, Xinjiang, China
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, Shandong, China
- Graduate University of Chinese Academy of Sciences, Beijing, China
- * E-mail:
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Chatterjee SJ, McCaffrey L. Emerging role of cell polarity proteins in breast cancer progression and metastasis. BREAST CANCER-TARGETS AND THERAPY 2014; 6:15-27. [PMID: 24648766 PMCID: PMC3929326 DOI: 10.2147/bctt.s43764] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Breast cancer is a heterogeneous group of diseases that frequently exhibits loss of growth control, and disrupted tissue organization and differentiation. Several recent studies indicate that apical–basal polarity provides a tumor-suppressive function, and that disrupting polarity proteins affects many stages of breast cancer progression from initiation through metastasis. In this review we highlight some of the recent advances in our understanding of the molecular mechanisms by which loss of apical–basal polarity deregulates apoptosis, proliferation, and promotes invasion and metastasis in breast cancer.
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Affiliation(s)
- Sudipa June Chatterjee
- Rosalind and Morris Goodman Cancer Centre, Department of Oncology, McGill University, Montreal, QC, Canada
| | - Luke McCaffrey
- Rosalind and Morris Goodman Cancer Centre, Department of Oncology, McGill University, Montreal, QC, Canada
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Par6b regulates the dynamics of apicobasal polarity during development of the stratified Xenopus epidermis. PLoS One 2013; 8:e76854. [PMID: 24204686 PMCID: PMC3800127 DOI: 10.1371/journal.pone.0076854] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 08/28/2013] [Indexed: 11/30/2022] Open
Abstract
During early vertebrate development, epithelial cells establish and maintain apicobasal polarity, failure of which can cause developmental defects or cancer metastasis. This process has been mostly studied in simple epithelia that have only one layer of cells, but is poorly understood in stratified epithelia. In this paper we address the role of the polarity protein Partitioning defective-6 homolog beta (Par6b) in the developing stratified epidermis of Xenopus laevis. At the blastula stage, animal blastomeres divide perpendicularly to the apicobasal axis to generate partially polarized superficial cells and non-polarized deep cells. Both cell populations modify their apicobasal polarity during the gastrula stage, before differentiating into the superficial and deep layers of epidermis. Early differentiation of the epidermis is normal in Par6b-depleted embryos; however, epidermal cells dissociate and detach from embryos at the tailbud stage. Par6b-depleted epidermal cells exhibit a significant reduction in basolaterally localized E-cadherin. Examination of the apical marker Crumbs homolog 3 (Crb3) and the basolateral marker Lethal giant larvae 2 (Lgl2) after Par6b depletion reveals that Par6b cell-autonomously regulates the dynamics of apicobasal polarity in both superficial and deep epidermal layers. Par6b is required to maintain the “basolateral” state in both epidermal layers, which explains the reduction of basolateral adhesion complexes and epidermal cells shedding.
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30
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Genetic deletion of Cadm4 results in myelin abnormalities resembling Charcot-Marie-Tooth neuropathy. J Neurosci 2013; 33:10950-61. [PMID: 23825401 DOI: 10.1523/jneurosci.0571-13.2013] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The interaction between myelinating Schwann cells and the axons they ensheath is mediated by cell adhesion molecules of the Cadm/Necl/SynCAM family. This family consists of four members: Cadm4/Necl4 and Cadm1/Necl2 are found in both glia and axons, whereas Cadm2/Necl3 and Cadm3/Necl1 are expressed by sensory and motor neurons. By generating mice lacking each of the Cadm genes, we now demonstrate that Cadm4 plays a role in the establishment of the myelin unit in the peripheral nervous system. Mice lacking Cadm4 (PGK-Cre/Cadm4(fl/fl)), but not Cadm1, Cadm2, or Cadm3, develop focal hypermyelination characterized by tomacula and myelin outfoldings, which are the hallmark of several Charcot-Marie-Tooth neuropathies. The absence of Cadm4 also resulted in abnormal axon-glial contact and redistribution of ion channels along the axon. These neuropathological features were also found in transgenic mice expressing a dominant-negative mutant of Cadm4 lacking its cytoplasmic domain in myelinating glia Tg(mbp-Cadm4dCT), as well as in mice lacking Cadm4 specifically in Schwann cells (DHH-Cre/Cadm4(fl/fl)). Consistent with these abnormalities, both PGK-Cre/Cadm4(fl/fl) and Tg(mbp-Cadm4dCT) mice exhibit impaired motor function and slower nerve conduction velocity. These findings indicate that Cadm4 regulates the growth of the myelin unit and the organization of the underlying axonal membrane.
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31
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Fedeles S, Gallagher AR. Cell polarity and cystic kidney disease. Pediatr Nephrol 2013; 28:1161-72. [PMID: 23161205 DOI: 10.1007/s00467-012-2337-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 10/02/2012] [Accepted: 10/02/2012] [Indexed: 10/27/2022]
Abstract
Epithelial cell polarity is essential for organ development; aberrations in this process have been implicated in various diseases, including polycystic kidney disease. Establishment and maintenance of cell polarity is governed by a number of molecular processes and how these processes operate remains an interesting question. Conserved protein complexes guide both apical-basolateral polarity and planar cell polarity. In this review we discuss the recent findings that provide insights into polarity mechanisms and the intriguing crosstalk between apical-basolateral polarity and planar cell polarity, and their relationship to cystic kidney disease.
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Affiliation(s)
- Sorin Fedeles
- Section of Nephrology, Department of Internal Medicine, Yale University School of Medicine, P.O. Box 208029, 333 Cedar Street, New Haven, CT 06520-8029, USA
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Hayase J, Kamakura S, Iwakiri Y, Yamaguchi Y, Izaki T, Ito T, Sumimoto H. The WD40 protein Morg1 facilitates Par6-aPKC binding to Crb3 for apical identity in epithelial cells. ACTA ACUST UNITED AC 2013; 200:635-50. [PMID: 23439680 PMCID: PMC3587828 DOI: 10.1083/jcb.201208150] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Formation of apico-basal polarity in epithelial cells is crucial for both morphogenesis (e.g., cyst formation) and function (e.g., tight junction development). Atypical protein kinase C (aPKC), complexed with Par6, is considered to translocate to the apical membrane and function in epithelial cell polarization. However, the mechanism for translocation of the Par6-aPKC complex has remained largely unknown. Here, we show that the WD40 protein Morg1 (mitogen-activated protein kinase organizer 1) directly binds to Par6 and thus facilitates apical targeting of Par6-aPKC in Madin-Darby canine kidney epithelial cells. Morg1 also interacts with the apical transmembrane protein Crumbs3 to promote Par6-aPKC binding to Crumbs3, which is reinforced with the apically localized small GTPase Cdc42. Depletion of Morg1 disrupted both tight junction development in monolayer culture and cyst formation in three-dimensional culture; apico-basal polarity was notably restored by forced targeting of aPKC to the apical surface. Thus, Par6-aPKC recruitment to the premature apical membrane appears to be required for definition of apical identity of epithelial cells.
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Affiliation(s)
- Junya Hayase
- Department of Biochemistry, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
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33
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Ngok SP, Geyer R, Liu M, Kourtidis A, Agrawal S, Wu C, Seerapu HR, Lewis-Tuffin LJ, Moodie KL, Huveldt D, Marx R, Baraban JM, Storz P, Horowitz A, Anastasiadis PZ. VEGF and Angiopoietin-1 exert opposing effects on cell junctions by regulating the Rho GEF Syx. ACTA ACUST UNITED AC 2012; 199:1103-15. [PMID: 23253477 PMCID: PMC3529520 DOI: 10.1083/jcb.201207009] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
VEGF causes translocation of Syx from endothelial cell junctions, promoting junction disassembly, whereas Angtiopoietin-1 maintains Syx at the junctions and stabilizes them. Vascular endothelial growth factor (VEGF) and Ang1 (Angiopoietin-1) have opposing effects on vascular permeability, but the molecular basis of these effects is not fully known. We report in this paper that VEGF and Ang1 regulate endothelial cell (EC) junctions by determining the localization of the RhoA-specific guanine nucleotide exchange factor Syx. Syx was recruited to junctions by members of the Crumbs polarity complex and promoted junction integrity by activating Diaphanous. VEGF caused translocation of Syx from cell junctions, promoting junction disassembly, whereas Ang1 maintained Syx at the junctions, inducing junction stabilization. The VEGF-induced translocation of Syx from EC junctions was caused by PKD1 (protein kinase D1)-mediated phosphorylation of Syx at Ser806, which reduced Syx association to its junctional anchors. In support of the pivotal role of Syx in regulating EC junctions, syx−/− mice had defective junctions, resulting in vascular leakiness, edema, and impaired heart function.
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Affiliation(s)
- Siu P Ngok
- Department of Cancer Biology, Mayo Clinic Comprehensive Cancer Center, Jacksonville, FL 32224, USA
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34
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Sen A, Nagy-Zsvér-Vadas Z, Krahn MP. Drosophila PATJ supports adherens junction stability by modulating Myosin light chain activity. ACTA ACUST UNITED AC 2012; 199:685-98. [PMID: 23128243 PMCID: PMC3494860 DOI: 10.1083/jcb.201206064] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The assembly and consolidation of the adherens junctions (AJs) are key events in the establishment of an intact epithelium. However, AJs are further modified to obtain flexibility for cell migration and morphogenetic movements. Intact AJs in turn are a prerequisite for the establishment and maintenance of apical-basal polarity in epithelial cells. In this study, we report that the conserved PDZ (PSD95, Discs large, ZO-1) domain-containing protein PATJ (Pals1-associated tight junction protein) was not per se crucial for the maintenance of apical-basal polarity in Drosophila melanogaster epithelial cells but rather regulated Myosin localization and phosphorylation. PATJ directly bound to the Myosin-binding subunit of Myosin phosphatase and decreased Myosin dephosphorylation, resulting in activated Myosin. Thereby, PATJ supports the stability of the Zonula Adherens. Notably, weakening of AJ in a PATJ mutant epithelium led first to a loss of Myosin from the AJ, subsequently to a disassembly of the AJ, and finally, to a loss of apical-basal polarity and disruption of the tissue.
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Affiliation(s)
- Arnab Sen
- Molecular and Cellular Anatomy, University of Regensburg, 93053 Regensburg, Germany
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35
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Tepass U. The apical polarity protein network in Drosophila epithelial cells: regulation of polarity, junctions, morphogenesis, cell growth, and survival. Annu Rev Cell Dev Biol 2012; 28:655-85. [PMID: 22881460 DOI: 10.1146/annurev-cellbio-092910-154033] [Citation(s) in RCA: 258] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Epithelial tissue formation and function requires the apical-basal polarization of individual epithelial cells. Apical polarity regulators (APRs) are an evolutionarily conserved group of key factors that govern polarity and several other aspects of epithelial differentiation. APRs compose a diverse set of molecules including a transmembrane protein (Crumbs), a serine/threonine kinase (aPKC), a lipid phosphatase (PTEN), a small GTPase (Cdc42), FERM domain proteins (Moesin, Yurt), and several adaptor or scaffolding proteins (Bazooka/Par3, Par6, Stardust, Patj). These proteins form a dynamic cooperative network that is engaged in negative-feedback regulation with basolateral polarity factors to set up the epithelial apical-basal axis. APRs support the formation of the apical junctional complex and the segregation of the junctional domain from the apical membrane. It is becoming increasingly clear that APRs interact with the cytoskeleton and vesicle trafficking machinery, regulate morphogenesis, and modulate epithelial cell growth and survival. Not surprisingly, APRs have multiple fundamental links to human diseases such as cancer and blindness.
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Affiliation(s)
- Ulrich Tepass
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada.
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36
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Zhou W, Hong Y. Drosophila Patj plays a supporting role in apical-basal polarity but is essential for viability. Development 2012; 139:2891-6. [PMID: 22791898 DOI: 10.1242/dev.083162] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Patj has been characterized as one of the so-called polarity proteins that play essential and conserved roles in regulating cell polarity in many different cell types. Studies of Drosophila and mammalian cells suggest that Patj is required for the apical polarity protein complex Crumbs-Stardust (Pals1 or Mpp5 in mammalian cells) to establish apical-basal polarity. However, owing to the lack of suitable genetic mutants, the exact in vivo function of Patj in regulating apical-basal polarity and development remains to be elucidated. Here, we generated molecularly defined null mutants of Drosophila Patj (dPatj). Our data show conclusively that dPatj only plays supporting and non-essential roles in regulating apical-basal polarity, although such a supporting role may become crucial in cells such as photoreceptors that undergo complex cellular morphogenesis. In addition, our results confirm that dPatj possesses an as yet unidentified function that is essential for pupal development.
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Affiliation(s)
- Wenke Zhou
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
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Cho SH, Kim JY, Simons DL, Song JY, Le JH, Swindell EC, Jamrich M, Wu SM, Kim S. Genetic ablation of Pals1 in retinal progenitor cells models the retinal pathology of Leber congenital amaurosis. Hum Mol Genet 2012; 21:2663-76. [PMID: 22398208 PMCID: PMC3363335 DOI: 10.1093/hmg/dds091] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 02/09/2012] [Accepted: 02/29/2012] [Indexed: 12/14/2022] Open
Abstract
Mutation of the polarity gene Crumbs homolog 1 (CRB1) is responsible for >10% of Leber congenital amaurosis (LCA) cases worldwide; LCA is characterized by early-onset degenerative retinal dystrophy. The role of CRB1 in LCA8 pathogenesis remains elusive since Crb1 mouse mutants, including a null allele, have failed to mimic the early-onset of LCA, most likely due to functional compensation by closely related genes encoding Crb2 and Crb3. Crb proteins form an evolutionarily conserved, apical polarity complex with the scaffolding protein associated with lin-seven 1 (Pals1), also known as MAGUK p55 subfamily member 5 (MPP5). Pals1 and Crbs are functionally inter-dependent in establishing and maintaining epithelial polarity. Pals1 is a single gene in the mouse and human genomes; therefore, we ablated Pals1 to establish a mouse genetic model mimicking human LCA. In our study, the deletion of Pals1 leads to the disruption of the apical localization of Crb proteins in retinal progenitors and the adult retina, validating their mutual interaction. Remarkably, the Pals1 mutant mouse exhibits the critical features of LCA such as early visual impairment as assessed by electroretinogram, disorganization of lamination and apical junctions and retinal degeneration. Our data uncover the indispensible role of Pals1 in retinal development, likely involving the maintenance of retinal polarity and survival of retinal neurons, thus providing the basis for the pathologic mechanisms of LCA8.
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Affiliation(s)
- Seo-Hee Cho
- Pediatric Research Center, Department of Pediatrics, University of Texas Health Science Center, Houston TX 77030, USA
- Shriners Hospitals Pediatric Research Center and Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Jin Young Kim
- Pediatric Research Center, Department of Pediatrics, University of Texas Health Science Center, Houston TX 77030, USA
- Shriners Hospitals Pediatric Research Center and Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | | | - Ji Yun Song
- Pediatric Research Center, Department of Pediatrics, University of Texas Health Science Center, Houston TX 77030, USA
- Shriners Hospitals Pediatric Research Center and Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Julie H. Le
- Pediatric Research Center, Department of Pediatrics, University of Texas Health Science Center, Houston TX 77030, USA
| | - Eric C. Swindell
- Pediatric Research Center, Department of Pediatrics, University of Texas Health Science Center, Houston TX 77030, USA
| | - Milan Jamrich
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston TX 77030, USA and
| | | | - Seonhee Kim
- Pediatric Research Center, Department of Pediatrics, University of Texas Health Science Center, Houston TX 77030, USA
- Shriners Hospitals Pediatric Research Center and Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
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Positive feedback and mutual antagonism combine to polarize Crumbs in the Drosophila follicle cell epithelium. Curr Biol 2012; 22:1116-22. [PMID: 22658591 DOI: 10.1016/j.cub.2012.04.020] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 03/06/2012] [Accepted: 04/11/2012] [Indexed: 12/15/2022]
Abstract
Epithelial tissues are composed of polarized cells with distinct apical and basolateral membrane domains. In the Drosophila ovarian follicle cell epithelium, apical membranes are specified by Crumbs (Crb), Stardust (Sdt), and the aPKC-Par6-cdc42 complex. Basolateral membranes are specified by Lethal giant larvae (Lgl), Discs large (Dlg), and Scribble (Scrib). Apical and basolateral determinants are known to act in a mutually antagonistic fashion, but it remains unclear how this interaction generates polarity. We have built a computer model of apicobasal polarity that suggests that the combination of positive feedback among apical determinants plus mutual antagonism between apical and basal determinants is essential for polarization. In agreement with this model, in vivo experiments define a positive feedback loop in which Crb self-recruits via Crb-Crb extracellular domain interactions, recruitment of Sdt-aPKC-Par6-cdc42, aPKC phosphorylation of Crb, and recruitment of Expanded (Ex) and Kibra (Kib) to prevent endocytic removal of Crb from the plasma membrane. Lgl antagonizes the operation of this feedback loop, explaining why apical determinants do not normally spread into the basolateral domain. Once Crb is removed from the plasma membrane, it undergoes recycling via Rab11 endosomes. Our results provide a dynamic model for understanding how epithelial polarity is maintained in Drosophila follicle cells.
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39
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Muschalik N, Knust E. Increased levels of the cytoplasmic domain of Crumbs repolarise developing Drosophila photoreceptors. J Cell Sci 2011; 124:3715-25. [PMID: 22025631 DOI: 10.1242/jcs.091223] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Photoreceptor morphogenesis in Drosophila requires remodelling of apico-basal polarity and adherens junctions (AJs), and includes cell shape changes, as well as differentiation and expansion of the apical membrane. The evolutionarily conserved transmembrane protein Crumbs (Crb) organises an apical membrane-associated protein complex that controls photoreceptor morphogenesis. Expression of the small cytoplasmic domain of Crb in crb mutant photoreceptor cells (PRCs) rescues the crb mutant phenotype to the same extent as the full-length protein. Here, we show that overexpression of the membrane-tethered cytoplasmic domain of Crb in otherwise wild-type photoreceptor cells has major effects on polarity and morphogenesis. Whereas early expression causes severe abnormalities in apico-basal polarity and ommatidial integrity, expression at later stages affects the shape and positioning of AJs. This result supports the importance of Crb for junctional remodelling during morphogenetic changes. The most pronounced phenotype observed upon early expression is the formation of ectopic apical membrane domains, which often develop into a complete second apical pole, including ectopic AJs. Induction of this phenotype requires members of the Par protein network. These data point to a close integration of the Crb complex and Par proteins during photoreceptor morphogenesis and underscore the role of Crb as an apical determinant.
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Affiliation(s)
- Nadine Muschalik
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307-Dresden, Germany
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Apico-basal polarity in polycystic kidney disease epithelia. Biochim Biophys Acta Mol Basis Dis 2011; 1812:1239-48. [DOI: 10.1016/j.bbadis.2011.05.008] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 05/19/2011] [Accepted: 05/24/2011] [Indexed: 12/29/2022]
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41
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Apical protein transport and lumen morphogenesis in polarized epithelial cells. Biosci Rep 2011; 31:245-56. [PMID: 21366541 DOI: 10.1042/bsr20100119] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Segregation of the apical and basolateral plasma membrane domains is the key distinguishing feature of epithelial cells. A series of interrelated cues and processes follow this primary polarization event, resulting in the morphogenesis of the mammalian epithelium. This review focuses on the role of the interactions between the extracellular matrix and neighbouring cells during the initiation and establishment of epithelial polarity, and the role that membrane transport and polarity complexes play in this process. An overview of the formation of the apical junctional complexes is given in relation to the generation of distinct membrane domains characterized by the asymmetric distribution of phosphoinositides and proteins. The mechanisms and machinery utilized by the trafficking pathways involved in the generation and maintenance of this apical-basolateral polarization are expounded, highlighting processes of apical-directed transport. Furthermore, the current proposed mechanisms for the organization of entire networks of cells into a structured, polarized three-dimensional structure are described, with an emphasis on the proposed mechanisms for the formation and expansion of the apical lumen.
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42
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Pieczynski J, Margolis B. Protein complexes that control renal epithelial polarity. Am J Physiol Renal Physiol 2011; 300:F589-601. [PMID: 21228104 DOI: 10.1152/ajprenal.00615.2010] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Establishment of epithelial apicobasal polarity is crucial for proper kidney development and function. In recent years, there have been important advances in our understanding of the factors that mediate the initiation of apicobasal polarization. Key among these are the polarity complexes that are evolutionarily conserved from simple organisms to humans. Three of these complexes are discussed in this review: the Crumbs complex, the Par complex, and the Scribble complex. The apical Crumbs complex consists of three proteins, Crumbs, PALS1, and PATJ, whereas the apical Par complex consists of Par-3, Par-6, and atypical protein kinase C. The lateral Scribble complex consists of Scribble, discs large, and lethal giant larvae. These complexes modulate kinase and small G protein activity such that the apical and basolateral complexes signal antagonistically, leading to the segregation of the apical and basolateral membranes. The polarity complexes also serve as scaffolds to direct and retain proteins at the apical membrane, the basolateral membrane, or the intervening tight junction. There is plasticity in apicobasal polarity, and this is best seen in the processes of epithelial-to-mesenchymal transition and the converse mesenchymal-to-epithelial transition. These transitions are important in kidney disease as well as kidney development, and modulation of the polarity complexes are critical for these transitions.
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Affiliation(s)
- Jay Pieczynski
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan, USA
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43
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Krahn MP, Bückers J, Kastrup L, Wodarz A. Formation of a Bazooka-Stardust complex is essential for plasma membrane polarity in epithelia. ACTA ACUST UNITED AC 2010; 190:751-60. [PMID: 20819933 PMCID: PMC2935580 DOI: 10.1083/jcb.201006029] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Recruitment of the Crumbs–Stardust polarity complex depends on interactions between Bazooka and the Stardust PDZ domain and is regulated by aPKC-mediated phosphorylation. Apical–basal polarity in Drosophila melanogaster epithelia depends on several evolutionarily conserved proteins that have been assigned to two distinct protein complexes: the Bazooka (Baz)–PAR-6 (partitioning defective 6)–atypical protein kinase C (aPKC) complex and the Crumbs (Crb)–Stardust (Sdt) complex. These proteins operate in a functional hierarchy, in which Baz is required for the proper subcellular localization of all other proteins. We investigated how these proteins interact and how this interaction is regulated. We show that Baz recruits Sdt to the plasma membrane by direct interaction between the Postsynaptic density 95/Discs large/Zonula occludens 1 (PDZ) domain of Sdt and a region of Baz that contains a phosphorylation site for aPKC. Phosphorylation of Baz causes the dissociation of the Baz–Sdt complex. Overexpression of a nonphosphorylatable version of Baz blocks the dissociation of Sdt from Baz, causing phenotypes very similar to those of crb and sdt mutations. Our findings provide a molecular mechanism for the phosphorylation-dependent interaction between the Baz–PAR-3 and Crb complexes during the establishment of epithelial polarity.
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Affiliation(s)
- Michael P Krahn
- Abteilung Stammzellbiologie, Forschungszentrum der Deutschen Forschungsgemeinschaft für Molekularphysiologie des Gehirns (CMPB), Georg-August-Universität Göttingen, 37077 Göttingen, Germany
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Bulgakova NA, Rentsch M, Knust E. Antagonistic functions of two stardust isoforms in Drosophila photoreceptor cells. Mol Biol Cell 2010; 21:3915-25. [PMID: 20861315 PMCID: PMC2982133 DOI: 10.1091/mbc.e09-10-0917] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Two Stardust isoforms are expressed in adult Drosophila photoreceptors, which associate with Crumbs and PATJ, but form distinct complexes. Sdt-H and Sdt-D have antagonistic functions on stalk membrane length and light-dependent retinal degeneration, suggesting a fine-tuned balance of different Crumbs complexes regulating photoreceptor homeostasis. Membrane-associated guanylate kinases (MAGUKs) are scaffolding proteins that organize supramolecular protein complexes, thereby partitioning the plasma membrane into spatially and functionally distinct subdomains. Their modular organization is ideally suited to organize protein complexes with cell type- or stage-specific composition, or both. Often more than one MAGUK isoform is expressed by one gene in the same cell, yet very little is known about their individual in vivo functions. Here, we show that two isoforms of Drosophila stardust, Sdt-H (formerly called Sdt-B2) and Sdt-D, which differ in their N terminus, are expressed in adult photoreceptors. Both isoforms associate with Crumbs and PATJ, constituents of the conserved Crumbs–Stardust complex. However, they form distinct complexes, localized at the stalk, a restricted region of the apical plasma membrane. Strikingly, Sdt-H and Sdt-D have antagonistic functions. While Sdt-H overexpression increases stalk membrane length and prevents light-dependent retinal degeneration, Sdt-D overexpression reduces stalk length and enhances light-dependent retinal degeneration. These results suggest that a fine-tuned balance of different Crumbs complexes regulates photoreceptor homeostasis.
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Affiliation(s)
- Natalia A Bulgakova
- Max-Planck-Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
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45
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Morais-de-Sá E, Mirouse V, St Johnston D. aPKC phosphorylation of Bazooka defines the apical/lateral border in Drosophila epithelial cells. Cell 2010; 141:509-23. [PMID: 20434988 PMCID: PMC2885938 DOI: 10.1016/j.cell.2010.02.040] [Citation(s) in RCA: 215] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 01/08/2010] [Accepted: 02/23/2010] [Indexed: 12/15/2022]
Abstract
Bazooka (PAR-3), PAR-6, and aPKC form a complex that plays a key role in the polarization of many cell types. In epithelial cells, however, Bazooka localizes below PAR-6 and aPKC at the apical/lateral junction. Here, we show that Baz is excluded from the apical aPKC domain in epithelia by aPKC phosphorylation, which disrupts the Baz/aPKC interaction. Removal of Baz from the complex is epithelial-specific because it also requires the Crumbs complex, which prevents the Baz/PAR-6 interaction. In the absence of Crumbs or aPKC phosphorylation of Baz, mislocalized Baz recruits adherens junction components apically, leading to a loss of the apical domain and an expansion of lateral. Thus, apical exclusion of Baz by Crumbs and aPKC defines the apical/lateral border. Although Baz acts as an aPKC targeting and specificity factor in nonepithelial cells, our results reveal that it performs a complementary function in positioning the adherens junction in epithelia.
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Affiliation(s)
- Eurico Morais-de-Sá
- The Gurdon Institute and the Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
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46
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Li J, Kim H, Aceto DG, Hung J, Aono S, Kemphues KJ. Binding to PKC-3, but not to PAR-3 or to a conventional PDZ domain ligand, is required for PAR-6 function in C. elegans. Dev Biol 2010; 340:88-98. [PMID: 20122916 DOI: 10.1016/j.ydbio.2010.01.023] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Revised: 12/28/2009] [Accepted: 01/25/2010] [Indexed: 12/18/2022]
Abstract
PAR-6 is a conserved protein important for establishment and maintenance of cell polarity in a variety of metazoans. PAR-6 proteins function together with PAR-3, aPKC and CDC-42. Mechanistic details of their interactions, however, are not fully understood. We studied the biochemical interactions between C. elegans PAR-6 and its binding partners and tested the requirements of these interactions in living worms. We show that PB1 domain-mediated binding of PAR-6 to PKC-3 is necessary for polarity establishment and PAR-6 cortical localization in C. elegans embryos. We also show that binding of PAR-6 and PAR-3 is mediated in vitro by a novel type of PDZ-PDZ interaction; the betaC strand of PAR-6 PDZ binds the betaD strand of PAR-3 PDZ1. However, this interaction is dispensable in vivo for PAR-6 function throughout the life of C. elegans. Mutations that specifically abolish conventional ligand binding to the PAR-6 PDZ domain also failed to affect PAR-6 function in vivo. We conclude that PAR-6 binding to PKC-3, but not to PAR-3 nor to a conventional PDZ ligand, is required for PAR-6 cortical localization and function in C. elegans.
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Affiliation(s)
- Jin Li
- Department of Molecular Biology and Genetics, 107 Biotechnology Building, Cornell University, Ithaca, NY 14853, USA
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47
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Wong EWP, Cheng CY. Polarity proteins and cell-cell interactions in the testis. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 278:309-53. [PMID: 19815182 DOI: 10.1016/s1937-6448(09)78007-4] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In mammalian testes, extensive junction restructuring takes place in the seminiferous epithelium at the Sertoli-Sertoli and Sertoli-germ cell interface to facilitate the different cellular events of spermatogenesis, such as mitosis, meiosis, spermiogenesis, and spermiation. Recent studies in the field have shown that Rho GTPases and polarity proteins play significant roles in the events of cell-cell interactions. Furthermore, Rho GTPases, such as Cdc42, are working in concert with polarity proteins in regulating cell polarization and cell adhesion at both the blood-testis barrier (BTB) and apical ectoplasmic specialization (apical ES) in the testis of adult rats. In this chapter, we briefly summarize recent findings on the latest status of research and development regarding Cdc42 and polarity proteins and how they affect cell-cell interactions in the testis and other epithelia. More importantly, we provide a new model in which how Cdc42 and components of the polarity protein complexes work in concert with laminin fragments, cytokines, and testosterone to regulate the events of cell-cell interactions in the seminiferous epithelium via a local autocrine-based regulatory loop known as the apical ES-BTB-basement membrane axis. This new functional axis coordinates various cellular events during different stages of the seminiferous epithelium cycle of spermatogenesis.
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Affiliation(s)
- Elissa W P Wong
- Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York 10065, USA
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Kim S, Gailite I, Moussian B, Luschnig S, Goette M, Fricke K, Honemann-Capito M, Grubmüller H, Wodarz A. Kinase-activity-independent functions of atypical protein kinase C in Drosophila. J Cell Sci 2009; 122:3759-71. [PMID: 19789180 DOI: 10.1242/jcs.052514] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Polarity of many cell types is controlled by a protein complex consisting of Bazooka/PAR-3 (Baz), PAR-6 and atypical protein kinase C (aPKC). In Drosophila, the Baz-PAR-6-aPKC complex is required for the control of cell polarity in the follicular epithelium, in ectodermal epithelia and neuroblasts. aPKC is the main signaling component of this complex that functions by phosphorylating downstream targets, while the PDZ domain proteins Baz and PAR-6 control the subcellular localization and kinase activity of aPKC. We compared the mutant phenotypes of an aPKC null allele with those of four novel aPKC alleles harboring point mutations that abolish the kinase activity or the binding of aPKC to PAR-6. We show that these point alleles retain full functionality in the control of follicle cell polarity, but produce strong loss-of-function phenotypes in embryonic epithelia and neuroblasts. Our data, combined with molecular dynamics simulations, show that the kinase activity of aPKC and its ability to bind PAR-6 are only required for a subset of its functions during development, revealing tissue-specific differences in the way that aPKC controls cell polarity.
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Affiliation(s)
- Soya Kim
- Department of Stem Cell Biology, DFG Research Center for Molecular Physiology of the Brain, Georg-August-University Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany
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49
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Bulgakova NA, Knust E. The Crumbs complex: from epithelial-cell polarity to retinal degeneration. J Cell Sci 2009; 122:2587-96. [DOI: 10.1242/jcs.023648] [Citation(s) in RCA: 190] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The evolutionarily conserved Crumbs protein complex is a key regulator of cell polarity and cell shape in both invertebrates and vertebrates. The important role of this complex in normal cell function is illustrated by the finding that mutations in one of its components, Crumbs, are associated with retinal degeneration in humans, mice and flies. Recent results suggest that the Crumbs complex plays a role in the development of other disease processes that are based on epithelial dysfunction, such as tumorigenesis or the formation of cystic kidneys. Localisation of the complex is restricted to a distinct region of the apical plasma membrane that abuts the zonula adherens in epithelia and photoreceptor cells of invertebrates and vertebrates, including humans. In addition to the core components, a variety of other proteins can be recruited to the complex, depending on the cell type and/or developmental stage. Together with diverse post-transcriptional and post-translational mechanisms that regulate the individual components, this provides an enormous functional diversity and flexibility of the complex. In this Commentary, we summarise findings concerning the organisation and modification of the Crumbs complex, and the conservation of its constituents from flies to mammals. In addition, we discuss recent results that suggest its participation in various human diseases, including blindness and tumour formation.
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Affiliation(s)
- Natalia A. Bulgakova
- Max-Planck Institute for Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, Dresden, Germany
| | - Elisabeth Knust
- Max-Planck Institute for Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, Dresden, Germany
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50
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Wang Z, Sandiford S, Wu C, Li SSC. Numb regulates cell-cell adhesion and polarity in response to tyrosine kinase signalling. EMBO J 2009; 28:2360-73. [PMID: 19609305 PMCID: PMC2712596 DOI: 10.1038/emboj.2009.190] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2009] [Accepted: 06/05/2009] [Indexed: 12/18/2022] Open
Abstract
Epithelial-mesenchymal transition (EMT), which can be caused by aberrant tyrosine kinase signalling, marks epithelial tumour progression and metastasis, yet the underlying molecular mechanism is not fully understood. Here, we report that Numb interacts with E-cadherin (E-cad) through its phosphotyrosine-binding domain (PTB) and thereby regulates the localization of E-cad to the lateral domain of epithelial cell–cell junction. Moreover, Numb engages the polarity complex Par3–aPKC–Par6 by binding to Par3 in polarized Madin-Darby canine kidney cells. Intriguingly, after Src activation or hepatocyte growth factor (HGF) treatment, Numb decouples from E-cad and Par3 and associates preferably with aPKC–Par6. Binding of Numb to aPKC is necessary for sequestering the latter in the cytosol during HGF-induced EMT. Knockdown of Numb by small hairpin RNA caused a basolateral-to-apicolateral translocation of E-cad and β-catenin accompanied by elevated actin polymerization, accumulation of Par3 and aPKC in the nucleus, an enhanced sensitivity to HGF-induced cell scattering, a decrease in cell–cell adhesion, and an increase in cell migration. Our work identifies Numb as an important regulator of epithelial polarity and cell–cell adhesion and a sensor of HGF signalling or Src activity during EMT.
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Affiliation(s)
- Zezhou Wang
- Department of Biochemistry and the Siebens-Drake Medical Research Institute, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
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