1
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Lade JM, Andrade MR, Undem C, Walker J, Jiang H, Yun X, Shimoda LA. Hypoxia enhances interactions between Na +/H + exchanger isoform 1 and actin filaments via ezrin in pulmonary vascular smooth muscle. Front Physiol 2023; 14:1108304. [PMID: 36926194 PMCID: PMC10011449 DOI: 10.3389/fphys.2023.1108304] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 01/24/2023] [Indexed: 03/08/2023] Open
Abstract
Exposure to hypoxia, due to high altitude or chronic lung disease, leads to structural changes in the pulmonary vascular wall, including hyperplasia and migration of pulmonary arterial smooth muscle cells (PASMCs). Previous studies showed that hypoxia upregulates the expression of Na+/H+ exchanger isoform 1 (NHE1) and that inhibition or loss of NHE1 prevents hypoxia-induced PASMC migration and proliferation. The exact mechanism by which NHE1 controls PASMC function has not been fully delineated. In fibroblasts, NHE1 has been shown to act as a membrane anchor for actin filaments, via binding of the adaptor protein, ezrin. Thus, in this study, we tested the role of ezrin and NHE1/actin interactions in controlling PASMC function. Using rat PASMCs exposed to in vitro hypoxia (4% O2, 24 h) we found that hypoxic exposure increased phosphorylation (activation) of ezrin, and promoted interactions between NHE1, phosphorylated ezrin and smooth muscle specific α-actin (SMA) as measured via immunoprecipitation and co-localization. Overexpression of wild-type human NHE1 in the absence of hypoxia was sufficient to induce PASMC migration and proliferation, whereas inhibiting ezrin phosphorylation with NSC668394 suppressed NHE1/SMA co-localization and migration in hypoxic PASMCs. Finally, overexpressing a version of human NHE1 in which amino acids were mutated to prevent NHE1/ezrin/SMA interactions was unable to increase PASMC migration and proliferation despite exhibiting normal Na+/H+ exchange activity. From these results, we conclude that hypoxic exposure increases ezrin phosphorylation in PASMCs, leading to enhanced ezrin/NHE1/SMA interaction. We further speculate that these interactions promote anchoring of the actin cytoskeleton to the membrane to facilitate the changes in cell movement and shape required for migration and proliferation.
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Affiliation(s)
- Julie M Lade
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Baltimore, MD, United States
| | - Manuella R Andrade
- Department of Physiology, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Clark Undem
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Baltimore, MD, United States
| | - Jasmine Walker
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Baltimore, MD, United States
| | - Haiyang Jiang
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Baltimore, MD, United States
| | - Xin Yun
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Baltimore, MD, United States
| | - Larissa A Shimoda
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Baltimore, MD, United States
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2
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Fujiwara S, Nguyen TP, Furuse K, Fukazawa Y, Otani T, Furuse M. Tight junction formation by a claudin mutant lacking the COOH-terminal PDZ domain-binding motif. Ann N Y Acad Sci 2022; 1516:85-94. [PMID: 35945631 DOI: 10.1111/nyas.14881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Claudin-based tight junctions (TJs) are formed at the most apical part of cell-cell contacts in epithelial cells. Previous studies suggest that scaffolding proteins ZO-1 and ZO-2 (ZO proteins) determine the location of TJs by interacting with claudins, but this idea is not conclusive. To address the role of the ZO proteins binding to claudins at TJs, a COOH-terminal PDZ domain binding motif-deleted claudin-3 mutant, which lacks the ZO protein binding, was stably expressed in claudin-deficient MDCK cells. The COOH-terminus-deleted claudin-3 was localized at the apicolateral region similar to full-length claudin-3. Consistently, freeze-fracture electron microscopy revealed that the COOH-terminus-deleted claudin-3-expressing cells reconstituted belts of TJs at the most apical region of the lateral membrane and restored functional epithelial barriers. These results suggest that the interaction of claudins with ZO proteins is not a prerequisite for TJ formation at the most apical part of cell-cell contacts.
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Affiliation(s)
- Sachiko Fujiwara
- Division of Cell Structure, National Institute for Physiological Sciences, Okazaki, Japan.,Department of Physiological Sciences, School of Life Science, SOKENDAI, The Graduate University for Advanced Studies, Okazaki, Japan
| | - Thanh Phuong Nguyen
- Division of Cell Structure, National Institute for Physiological Sciences, Okazaki, Japan.,Department of Physiological Sciences, School of Life Science, SOKENDAI, The Graduate University for Advanced Studies, Okazaki, Japan
| | - Kyoko Furuse
- Division of Cell Structure, National Institute for Physiological Sciences, Okazaki, Japan
| | - Yugo Fukazawa
- Division of Brain Structure and Function, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.,Life Science Innovation Center, University of Fukui, Fukui, Japan
| | - Tetsuhisa Otani
- Division of Cell Structure, National Institute for Physiological Sciences, Okazaki, Japan.,Department of Physiological Sciences, School of Life Science, SOKENDAI, The Graduate University for Advanced Studies, Okazaki, Japan
| | - Mikio Furuse
- Division of Cell Structure, National Institute for Physiological Sciences, Okazaki, Japan.,Department of Physiological Sciences, School of Life Science, SOKENDAI, The Graduate University for Advanced Studies, Okazaki, Japan.,Nagoya University Graduate School of Medicine, Aichi, Japan
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3
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Kubo A, Aoki S, Fujita H. Whole-Mount Preparation and Microscopic Analysis of Epidermis. Curr Protoc 2022; 2:e464. [PMID: 35816161 DOI: 10.1002/cpz1.464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The epidermis is a stratified epithelium. Compared to that for monolayered epithelia, understanding of the cell biology of stratified epithelia lags far behind. The major reason for this is the limitation of methods to reproduce the epidermis in vitro using cultured keratinocytes: for example, cultured keratinocyte cell sheets lack Langerhans cells, melanocytes, nerves, sweat ducts, and hair follicles. One current way to overcome this limitation is to observe the epidermis in vivo via whole-mount staining and three-dimensional imaging. Here, we describe how to prepare epidermal sheets from skin and how to immunostain and observe them in whole mount. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Preparation of mouse epidermal sheets by the ammonium thiocyanate method Alternate Protocol: Preparation of mouse epidermal sheets by the dispase method Basic Protocol 2: Preparation of human epidermal sheets by the dispase method Basic Protocol 3: Whole-mount immunostaining of epidermis.
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Affiliation(s)
- Akiharu Kubo
- Division of Dermatology, Department of Internal Related, Kobe University Graduate School of Medicine, Kobe, Japan
- Department of Dermatology, Keio University School of Medicine, Tokyo, Japan
| | - Satomi Aoki
- Department of Dermatology, Keio University School of Medicine, Tokyo, Japan
| | - Harumi Fujita
- Department of Dermatology, Keio University School of Medicine, Tokyo, Japan
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4
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Zaman R, Lombardo A, Sauvanet C, Viswanatha R, Awad V, Bonomo LER, McDermitt D, Bretscher A. Effector-mediated ERM activation locally inhibits RhoA activity to shape the apical cell domain. J Cell Biol 2021; 220:211973. [PMID: 33836044 PMCID: PMC8185690 DOI: 10.1083/jcb.202007146] [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: 07/27/2020] [Revised: 02/07/2021] [Accepted: 03/09/2021] [Indexed: 12/21/2022] Open
Abstract
Activated ezrin-radixin-moesin (ERM) proteins link the plasma membrane to the actin cytoskeleton to generate apical structures, including microvilli. Among many kinases implicated in ERM activation are the homologues LOK and SLK. CRISPR/Cas9 was used to knock out all ERM proteins or LOK/SLK in human cells. LOK/SLK knockout eliminates all ERM-activating phosphorylation. The apical domains of cells lacking LOK/SLK or ERMs are strikingly similar and selectively altered, with loss of microvilli and with junctional actin replaced by ectopic myosin-II–containing apical contractile structures. Constitutively active ezrin can reverse the phenotypes of either ERM or LOK/SLK knockouts, indicating that a central function of LOK/SLK is to activate ERMs. Both knockout lines have elevated active RhoA with concomitant enhanced myosin light chain phosphorylation, revealing that active ERMs are negative regulators of RhoA. As RhoA-GTP activates LOK/SLK to activate ERM proteins, the ability of active ERMs to negatively regulate RhoA-GTP represents a novel local feedback loop necessary for the proper apical morphology of epithelial cells.
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Affiliation(s)
- Riasat Zaman
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY
| | - Andrew Lombardo
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY
| | - Cécile Sauvanet
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY
| | - Raghuvir Viswanatha
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY
| | - Valerie Awad
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY
| | - Locke Ezra-Ros Bonomo
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY
| | - David McDermitt
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY
| | - Anthony Bretscher
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY
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5
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Robertson TF, Chengappa P, Gomez Atria D, Wu CF, Avery L, Roy NH, Maillard I, Petrie RJ, Burkhardt JK. Lymphocyte egress signal sphingosine-1-phosphate promotes ERM-guided, bleb-based migration. J Cell Biol 2021; 220:211919. [PMID: 33764397 PMCID: PMC8006814 DOI: 10.1083/jcb.202007182] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 02/07/2021] [Accepted: 03/03/2021] [Indexed: 02/04/2023] Open
Abstract
Ezrin, radixin, and moesin (ERM) family proteins regulate cytoskeletal responses by tethering the plasma membrane to the underlying actin cortex. Mutations in ERM proteins lead to severe combined immunodeficiency, but the function of these proteins in T cells remains poorly defined. Using mice in which T cells lack all ERM proteins, we demonstrate a selective role for these proteins in facilitating S1P-dependent egress from lymphoid organs. ERM-deficient T cells display defective S1P-induced migration in vitro, despite normal responses to standard protein chemokines. Analysis of these defects revealed that S1P promotes a fundamentally different mode of migration than chemokines, characterized by intracellular pressurization and bleb-based motility. ERM proteins facilitate this process, controlling directional migration by limiting blebbing to the leading edge. We propose that the distinct modes of motility induced by S1P and chemokines are specialized to allow T cell migration across lymphatic barriers and through tissue stroma, respectively.
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Affiliation(s)
- Tanner F Robertson
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA.,Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | | | - Daniela Gomez Atria
- Division of Hematology-Oncology, Department of Medicine, Abramson Family Cancer Research Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA
| | - Christine F Wu
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA.,Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Lyndsay Avery
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA.,Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Nathan H Roy
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA.,Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Ivan Maillard
- Division of Hematology-Oncology, Department of Medicine, Abramson Family Cancer Research Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA
| | - Ryan J Petrie
- Department of Biology, Drexel University, Philadelphia, PA
| | - Janis K Burkhardt
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA.,Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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6
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Liu H, Zhang CH, Ammanamanchi N, Suresh S, Lewarchik C, Rao K, Uys GM, Han L, Abrial M, Yimlamai D, Ganapathy B, Guillermier C, Chen N, Khaladkar M, Spaethling J, Eberwine JH, Kim J, Walsh S, Choudhury S, Little K, Francis K, Sharma M, Viegas M, Bais A, Kostka D, Ding J, Bar-Joseph Z, Wu Y, Yechoor V, Moulik M, Johnson J, Weinberg J, Reyes-Múgica M, Steinhauser ML, Kühn B. Control of cytokinesis by β-adrenergic receptors indicates an approach for regulating cardiomyocyte endowment. Sci Transl Med 2020; 11:11/513/eaaw6419. [PMID: 31597755 PMCID: PMC8132604 DOI: 10.1126/scitranslmed.aaw6419] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 06/10/2019] [Accepted: 08/30/2019] [Indexed: 12/28/2022]
Abstract
One million patients with congenital heart disease (CHD) live in the United States. They have a lifelong risk of developing heart failure. Current concepts do not sufficiently address mechanisms of heart failure development specifically for these patients. Here, analysis of heart tissue from an infant with tetralogy of Fallot with pulmonary stenosis (ToF/PS) labeled with isotope-tagged thymidine demonstrated that cardiomyocyte cytokinesis failure is increased in this common form of CHD. We used single-cell transcriptional profiling to discover that the underlying mechanism of cytokinesis failure is repression of the cytokinesis gene ECT2, downstream of β-adrenergic receptors (β-ARs). Inactivation of the β-AR genes and administration of the β-blocker propranolol increased cardiomyocyte division in neonatal mice, which increased the number of cardiomyocytes (endowment) and conferred benefit after myocardial infarction in adults. Propranolol enabled the division of ToF/PS cardiomyocytes in vitro. These results suggest that β-blockers could be evaluated for increasing cardiomyocyte division in patients with ToF/PS and other types of CHD.
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Affiliation(s)
- Honghai Liu
- Richard King Mellon Foundation Institute for Pediatric Research and Division of Cardiology, UPMC Children's Hospital of Pittsburgh and Department of Pediatrics, University of Pittsburgh, Pittsburgh, PA 15224, USA
| | - Cheng-Hai Zhang
- Department of Cardiology, Boston Children's Hospital, Boston, MA 02115, USA.,Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Niyatie Ammanamanchi
- Richard King Mellon Foundation Institute for Pediatric Research and Division of Cardiology, UPMC Children's Hospital of Pittsburgh and Department of Pediatrics, University of Pittsburgh, Pittsburgh, PA 15224, USA
| | - Sangita Suresh
- Department of Cardiology, Boston Children's Hospital, Boston, MA 02115, USA.,Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Christopher Lewarchik
- Richard King Mellon Foundation Institute for Pediatric Research and Division of Cardiology, UPMC Children's Hospital of Pittsburgh and Department of Pediatrics, University of Pittsburgh, Pittsburgh, PA 15224, USA
| | - Krithika Rao
- Richard King Mellon Foundation Institute for Pediatric Research and Division of Cardiology, UPMC Children's Hospital of Pittsburgh and Department of Pediatrics, University of Pittsburgh, Pittsburgh, PA 15224, USA
| | - Gerrida M Uys
- Department of Cardiology, Boston Children's Hospital, Boston, MA 02115, USA.,Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Lu Han
- Richard King Mellon Foundation Institute for Pediatric Research and Division of Cardiology, UPMC Children's Hospital of Pittsburgh and Department of Pediatrics, University of Pittsburgh, Pittsburgh, PA 15224, USA
| | - Maryline Abrial
- Department of Cardiology, Boston Children's Hospital, Boston, MA 02115, USA.,Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Dean Yimlamai
- Department of Pediatric Gastroenterology, Hepatology and Nutrition, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA 15224, USA
| | - Balakrishnan Ganapathy
- Richard King Mellon Foundation Institute for Pediatric Research and Division of Cardiology, UPMC Children's Hospital of Pittsburgh and Department of Pediatrics, University of Pittsburgh, Pittsburgh, PA 15224, USA
| | - Christelle Guillermier
- Division of Genetics and Harvard Medical School, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Nathalie Chen
- Richard King Mellon Foundation Institute for Pediatric Research and Division of Cardiology, UPMC Children's Hospital of Pittsburgh and Department of Pediatrics, University of Pittsburgh, Pittsburgh, PA 15224, USA
| | - Mugdha Khaladkar
- Department of Biology, School of Arts and Sciences, University of Pennsylvania, 301A/B Lynch Laboratory, 433 S University Avenue, Philadelphia, PA 19104, USA
| | - Jennifer Spaethling
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - James H Eberwine
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Junhyong Kim
- Department of Biology, School of Arts and Sciences, University of Pennsylvania, 301A/B Lynch Laboratory, 433 S University Avenue, Philadelphia, PA 19104, USA
| | - Stuart Walsh
- Department of Cardiology, Boston Children's Hospital, Boston, MA 02115, USA.,Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Sangita Choudhury
- Department of Cardiology, Boston Children's Hospital, Boston, MA 02115, USA.,Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Kathryn Little
- Richard King Mellon Foundation Institute for Pediatric Research and Division of Cardiology, UPMC Children's Hospital of Pittsburgh and Department of Pediatrics, University of Pittsburgh, Pittsburgh, PA 15224, USA
| | - Kimberly Francis
- Richard King Mellon Foundation Institute for Pediatric Research and Division of Cardiology, UPMC Children's Hospital of Pittsburgh and Department of Pediatrics, University of Pittsburgh, Pittsburgh, PA 15224, USA
| | - Mahesh Sharma
- Division of Cardiothoracic Surgery, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Melita Viegas
- Pediatric Cardiothoracic Surgery, UPMC Children's Hospital of Pittsburgh and Department of Cardiothoracic Surgery, University of Pittsburgh, Pittsburgh, PA 15224, USA
| | - Abha Bais
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15201, USA
| | - Dennis Kostka
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15201, USA.,Department of Computational & Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA.,Pittsburgh Center for Evolutionary Biology and Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Jun Ding
- Computational Biology Department and Machine Learning Department, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Ziv Bar-Joseph
- Computational Biology Department and Machine Learning Department, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Yijen Wu
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15201, USA.,Rangos Research Center Animal Imaging Core, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA 15224, USA
| | - Vijay Yechoor
- Diabetes and Beta Cell Biology Center, Division of Endocrinology, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15238, USA
| | - Mousumi Moulik
- Division of Cardiology, Department of Pediatrics, UPMC Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
| | - Jennifer Johnson
- Division of Cardiology, Department of Pediatrics, UPMC Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA.,Neonatal-Perinatal Medicine, UPMC Magee-Womens Hospital, Pittsburgh, PA 15213, USA
| | - Jacqueline Weinberg
- Division of Cardiology, Department of Pediatrics, UPMC Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
| | - Miguel Reyes-Múgica
- Division of Pediatric Pathology, UPMC Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
| | - Matthew L Steinhauser
- Division of Genetics and Harvard Medical School, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Bernhard Kühn
- Richard King Mellon Foundation Institute for Pediatric Research and Division of Cardiology, UPMC Children's Hospital of Pittsburgh and Department of Pediatrics, University of Pittsburgh, Pittsburgh, PA 15224, USA. .,McGowan Institute of Regenerative Medicine, Pittsburgh, PA 15219, USA.,Pediatric Institute for Heart Regeneration and Therapeutics, Pittsburgh, PA 15224, USA
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7
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Derouiche A, Geiger KD. Perspectives for Ezrin and Radixin in Astrocytes: Kinases, Functions and Pathology. Int J Mol Sci 2019; 20:ijms20153776. [PMID: 31382374 PMCID: PMC6695708 DOI: 10.3390/ijms20153776] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 07/30/2019] [Accepted: 07/31/2019] [Indexed: 02/06/2023] Open
Abstract
Astrocytes are increasingly perceived as active partners in physiological brain function and behaviour. The structural correlations of the glia–synaptic interaction are the peripheral astrocyte processes (PAPs), where ezrin and radixin, the two astrocytic members of the ezrin-radixin-moesin (ERM) family of proteins are preferentially localised. While the molecular mechanisms of ERM (in)activation appear universal, at least in mammalian cells, and have been studied in great detail, the actual ezrin and radixin kinases, phosphatases and binding partners appear cell type specific and may be multiplexed within a cell. In astrocytes, ezrin is involved in process motility, which can be stimulated by the neurotransmitter glutamate, through activation of the glial metabotropic glutamate receptors (mGluRs) 3 or 5. However, it has remained open how this mGluR stimulus is transduced to ezrin activation. Knowing upstream signals of ezrin activation, ezrin kinase(s), and membrane-bound binding partners of ezrin in astrocytes might open new approaches to the glial role in brain function. Ezrin has also been implicated in invasive behaviour of astrocytomas, and glial activation. Here, we review data pertaining to potential molecular interaction partners of ezrin in astrocytes, with a focus on PKC and GRK2, and in gliomas and other diseases, to stimulate further research on their potential roles in glia-synaptic physiology and pathology.
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Affiliation(s)
- Amin Derouiche
- Institute of Anatomy II, Goethe-University Frankfurt, D-60590 Frankfurt am Main, Germany.
| | - Kathrin D Geiger
- Neuropathology, Institute for Pathology, Carl Gustav Carus University Hospital, TU Dresden, D-01307 Dresden, Germany
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8
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Diz-Muñoz A, Weiner OD, Fletcher DA. In pursuit of the mechanics that shape cell surfaces. NATURE PHYSICS 2018; 14:648-652. [PMID: 31007706 PMCID: PMC6469718 DOI: 10.1038/s41567-018-0187-8] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Revised: 04/09/2018] [Accepted: 05/25/2018] [Indexed: 05/25/2023]
Abstract
Robust and responsive, the surface of a cell is as important as its interior when it comes to mechanically regulating form and function. New techniques are shedding light on this role, and a common language to describe its properties is now needed.
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Affiliation(s)
- Alba Diz-Muñoz
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Orion D. Weiner
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA
| | - Daniel A. Fletcher
- Bioengineering Department and Biophysics Program, University of California Berkeley, Berkeley, CA, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, California, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
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9
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Abeysundara N, Simmonds AJ, Hughes SC. Moesin is involved in polarity maintenance and cortical remodeling during asymmetric cell division. Mol Biol Cell 2018; 29:419-434. [PMID: 29282284 PMCID: PMC6014166 DOI: 10.1091/mbc.e17-05-0294] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 12/08/2017] [Accepted: 12/13/2017] [Indexed: 01/17/2023] Open
Abstract
An intact actomyosin network is essential for anchoring polarity proteins to the cell cortex and maintaining cell size asymmetry during asymmetric cell division of Drosophila neuroblasts (NBs). However, the mechanisms that control changes in actomyosin dynamics during asymmetric cell division remain unclear. We find that the actin-binding protein, Moesin, is essential for NB proliferation and mitotic progression in the developing brain. During metaphase, phosphorylated Moesin (p-Moesin) is enriched at the apical cortex, and loss of Moesin leads to defects in apical polarity maintenance and cortical stability. This asymmetric distribution of p-Moesin is determined by components of the apical polarity complex and Slik kinase. During later stages of mitosis, p-Moesin localization shifts more basally, contributing to asymmetric cortical extension and myosin basal furrow positioning. Our findings reveal Moesin as a novel apical polarity protein that drives cortical remodeling of dividing NBs, which is essential for polarity maintenance and initial establishment of cell size asymmetry.
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Affiliation(s)
- Namal Abeysundara
- Department of Medical Genetics, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Andrew J Simmonds
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Sarah C Hughes
- Department of Medical Genetics, University of Alberta, Edmonton, AB T6G 2H7, Canada
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada
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10
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Takeya K, Kaneko T, Miyazu M, Takai A. Addition of urea and thiourea to electrophoresis sample buffer improves efficiency of protein extraction from TCA/acetone-treated smooth muscle tissues for phos-tag SDS-PAGE. Electrophoresis 2017; 39:326-333. [PMID: 29072784 DOI: 10.1002/elps.201700394] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 10/18/2017] [Indexed: 01/04/2023]
Abstract
Phosphorylation analysis by using phos-tag technique has been reported to be suitable for highly sensitive quantification of smooth muscle myosin regulatory light chain (LC20 ) phosphorylation. However, there is another factor that will affect the sensitivity of phosphorylation analysis, that is, protein extraction. Here, we optimized the conditions for total protein extraction out of trichloroacetic acid (TCA)-fixed tissues. Standard SDS sample buffer extracted less LC20 , actin and myosin phosphatase targeting subunit 1 (MYPT1) from TCA/acetone treated ciliary muscle strips. On the other hand, sample buffer containing urea and thiourea in addition to lithium dodecyl sulfate (LDS) or SDS extracted those proteins more efficiently, and thus increased the detection sensitivity up to 4-5 fold. Phos-tag SDS-PAGE separated dephosphorylated and phosphorylated LC20 s extracted in LDS/urea/thiourea sample buffer to the same extent as those in standard SDS buffer. We have concluded that LDS (or SDS) /urea/thiourea sample buffer is suitable for highly sensitive phosphorylation analysis in smooth muscle, especially when it is treated with TCA/acetone.
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Affiliation(s)
- Kosuke Takeya
- Department of Physiology, Asahikawa Medical University, Hokkaido, Japan
| | - Toshiyuki Kaneko
- Department of Physiology, Asahikawa Medical University, Hokkaido, Japan
| | - Motoi Miyazu
- Department of Physiology, Asahikawa Medical University, Hokkaido, Japan
| | - Akira Takai
- Department of Physiology, Asahikawa Medical University, Hokkaido, Japan
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11
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Hiruma S, Kamasaki T, Otomo K, Nemoto T, Uehara R. Dynamics and function of ERM proteins during cytokinesis in human cells. FEBS Lett 2017; 591:3296-3309. [DOI: 10.1002/1873-3468.12844] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 08/31/2017] [Accepted: 09/01/2017] [Indexed: 12/18/2022]
Affiliation(s)
- Shota Hiruma
- Graduate School of Life Science; Hokkaido University; Japan
| | | | - Kohei Otomo
- Research Institute for Electronic Science; Hokkaido University; Japan
| | - Tomomi Nemoto
- Research Institute for Electronic Science; Hokkaido University; Japan
| | - Ryota Uehara
- Graduate School of Life Science; Hokkaido University; Japan
- Creative Research Institution; Hokkaido University; Japan
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12
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Yano T, Kanoh H, Tamura A, Tsukita S. Apical cytoskeletons and junctional complexes as a combined system in epithelial cell sheets. Ann N Y Acad Sci 2017; 1405:32-43. [DOI: 10.1111/nyas.13432] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 06/12/2017] [Accepted: 06/14/2017] [Indexed: 12/13/2022]
Affiliation(s)
- Tomoki Yano
- Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine; Osaka University; Osaka Japan
| | - Hatsuho Kanoh
- Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine; Osaka University; Osaka Japan
- Graduate School of Biostudies; Kyoto University; Kyoto Japan
| | - Atsushi Tamura
- Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine; Osaka University; Osaka Japan
| | - Sachiko Tsukita
- Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine; Osaka University; Osaka Japan
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13
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Tavasoli M, Al-Momany A, Wang X, Li L, Edwards JC, Ballermann BJ. Both CLIC4 and CLIC5A activate ERM proteins in glomerular endothelium. Am J Physiol Renal Physiol 2016; 311:F945-F957. [PMID: 27582103 DOI: 10.1152/ajprenal.00353.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 08/25/2016] [Indexed: 01/17/2023] Open
Abstract
The chloride intracellular channel (CLIC) 5A is expressed at very high levels in renal glomeruli, in both endothelial cells (EC) and podocytes. CLIC5A stimulates Rac1- and phosphatidylinositol (4,5)-bisphosphate-dependent ERM (ezrin, radixin, moesin) activation. ERM proteins, in turn, function in lumen formation and in the development of actin-based cellular projections. In mice lacking CLIC5A, ERM phosphorylation is profoundly reduced in podocytes, but preserved in glomerular EC. Since glomerular EC also express CLIC4, we reasoned that, if CLIC4 activates ERM proteins like CLIC5A, then CLIC4 could compensate for the CLIC5A loss in glomerular EC. In glomeruli of CLIC5-deficient mice, CLIC4 expression was upregulated and colocalized with moesin and ezrin in glomerular EC, but not in podocytes. In cultured glomerular EC, CLIC4 silencing reduced ERM phosphorylation and cytoskeletal association, and expression of exogenous CLIC4 or CLIC5A rescued ERM de-phosphorylation due to CLIC4 silencing. In mice lacking either CLIC4 or CLIC5, ERM phosphorylation was retained in glomerular EC, but, in mice lacking both CLIC4 and CLIC5, glomerular EC ERM phosphorylation was profoundly reduced. Although glomerular EC fenestrae developed normally in dual CLIC4/CLIC5-deficient mice, the density of fenestrae declined substantially by 8 mo of age, along with the deposition of subendothelial electron-lucent material. The dual CLIC4/CLIC5-deficient mice developed spontaneous proteinuria, glomerular cell proliferation, and matrix deposition. Thus CLIC4 stimulates ERM activation and can compensate for CLIC5A in glomerular EC. The findings indicate that CLIC4/CLIC5A-mediated ERM activation is required for maintenance of the glomerular capillary architecture.
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Affiliation(s)
- Mahtab Tavasoli
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Abass Al-Momany
- Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; and
| | - Xin Wang
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Laiji Li
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - John C Edwards
- Department of Internal Medicine, St. Louis University, St. Louis, Missouri
| | - Barbara J Ballermann
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; .,Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; and
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14
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Forteza R, Figueroa Y, Mashukova A, Dulam V, Salas PJ. Conditional knockout of polarity complex (atypical) PKCι reveals an anti-inflammatory function mediated by NF-κB. Mol Biol Cell 2016; 27:2186-97. [PMID: 27226486 PMCID: PMC4945138 DOI: 10.1091/mbc.e16-02-0086] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 05/20/2016] [Indexed: 01/27/2023] Open
Abstract
Atypical PKC, Par6, and Par3 constitute a conserved complex signaling cell asymmetry. In contrast to its role in other tissues, atypical PKC inhibits NF-κB activation in epithelia and may function in maintaining low levels of inflammation in addition to establishing apicobasal polarity. The conserved proteins of the polarity complex made up of atypical PKC (aPKC, isoforms ι and ζ), Par6, and Par3 determine asymmetry in several cell types, from Caenorhabditis elegans oocytes to vertebrate epithelia and neurons. We previously showed that aPKC is down-regulated in intestinal epithelia under inflammatory stimulation. Further, expression of constitutively active PKCι decreases NF-κB activity in an epithelial cell line, the opposite of the effect reported in other cells. Here we tested the hypothesis that aPKC has a dual function in epithelia, inhibiting the NF-κB pathway in addition to having a role in apicobasal polarity. We achieved full aPKC down-regulation in small intestine villi and colon surface epithelium using a conditional epithelium-specific knockout mouse. The results show that aPKC is dispensable for polarity after cell differentiation, except for known targets, including ROCK and ezrin, claudin-4 expression, and barrier permeability. The aPKC defect resulted in increased NF-κB activity, which could be rescued by IKK and ROCK inhibitors. It also increased expression of proinflammatory cytokines. In contrast, expression of anti-inflammatory IL-10 decreased. We conclude that epithelial aPKC acts upstream of multiple mechanisms that participate in the inflammatory response in the intestine, including, but not restricted to, NF-κB.
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Affiliation(s)
- Radia Forteza
- Department of Cell Biology, University of Miami Miller School of Medicine, Miami, FL 33136
| | - Yolanda Figueroa
- Department of Cell Biology, University of Miami Miller School of Medicine, Miami, FL 33136
| | - Anastasia Mashukova
- Department of Cell Biology, University of Miami Miller School of Medicine, Miami, FL 33136 Department of Physiology, Nova Southeastern University, Ft. Lauderdale, FL 33314
| | - Vipin Dulam
- Department of Cell Biology, University of Miami Miller School of Medicine, Miami, FL 33136
| | - Pedro J Salas
- Department of Cell Biology, University of Miami Miller School of Medicine, Miami, FL 33136
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15
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Bui DA, Lee W, White AE, Harper JW, Schackmann RCJ, Overholtzer M, Selfors LM, Brugge JS. Cytokinesis involves a nontranscriptional function of the Hippo pathway effector YAP. Sci Signal 2016; 9:ra23. [PMID: 26933062 DOI: 10.1126/scisignal.aaa9227] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
YAP is a transcriptional coactivator that controls organ expansion and differentiation and is inhibited by the Hippo pathway in cells in interphase. Here, we demonstrated that, during mitosis, YAP localized to the midbody and spindle, subcellular structures that are involved in cytokinesis, the process by which contraction of the cytoskeleton produces two daughter cells. Furthermore, YAP was phosphorylated by CDK1, a kinase that promotes cell cycle progression. Knockdown of YAP by shRNA or expression of a nonphosphorylatable form of YAP delayed the separation of daughter cells (called abscission) and induced a cytokinesis phenotype associated with increased contractile force, membrane blebbing and bulges, and abnormal spindle orientation. Consequently, these defects led to an increased frequency of multinucleation, micronuclei, and aneuploidy. YAP was required for proper localization of proteins that regulate contraction during cytokinesis, including ECT2, MgcRacGap, Anillin, and RHOA. In addition, depletion of YAP increased the phosphorylation of myosin light chain, which would be expected to activate the contractile activity of myosin II, the molecular motor involved in cytokinesis. The polarity scaffold protein PATJ coprecipitated with YAP and colocalized with YAP at the cytokinesis midbody, and knockdown of PATJ phenocopied the cytokinetic defects and spindle orientation alterations induced by either YAP depletion or expression of a nonphosphorylatable YAP mutant. Together, these results reveal an unanticipated role for YAP in the proper organization of the cytokinesis machinery during mitosis through interaction with the polarity protein PATJ.
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Affiliation(s)
- Duyen Amy Bui
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Wendy Lee
- The Ronald O. Perelman Department of Dermatology and the Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
| | - Anne E White
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - J Wade Harper
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Ron C J Schackmann
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Michael Overholtzer
- BCMB (Biochemistry, Cell, and Molecular Biology) Allied Program, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA. Cell Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Laura M Selfors
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Joan S Brugge
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
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16
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Antoine-Bertrand J, Duquette PM, Alchini R, Kennedy TE, Fournier AE, Lamarche-Vane N. p120RasGAP Protein Mediates Netrin-1 Protein-induced Cortical Axon Outgrowth and Guidance. J Biol Chem 2015; 291:4589-602. [PMID: 26710849 DOI: 10.1074/jbc.m115.674846] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Indexed: 12/23/2022] Open
Abstract
The receptor deleted in colorectal cancer (DCC) mediates the attraction of growing axons to netrin-1 during brain development. In response to netrin-1 stimulation, DCC becomes a signaling platform to recruit proteins that promote axon outgrowth and guidance. The Ras GTPase-activating protein (GAP) p120RasGAP inhibits Ras activity and mediates neurite retraction and growth cone collapse in response to repulsive guidance cues. Here we show an interaction between p120RasGAP and DCC that positively regulates netrin-1-mediated axon outgrowth and guidance in embryonic cortical neurons. In response to netrin-1, p120RasGAP is recruited to DCC in growth cones and forms a multiprotein complex with focal adhesion kinase and ERK. We found that Ras/ERK activities are elevated aberrantly in p120RasGAP-deficient neurons. Moreover, the expression of p120RasGAP Src homology 2 (SH2)-SH3-SH2 domains, which interact with the C-terminal tail of DCC, is sufficient to restore netrin-1-dependent axon outgrowth in p120RasGAP-deficient neurons. We provide a novel mechanism that exploits the scaffolding properties of the N terminus of p120RasGAP to tightly regulate netrin-1/DCC-dependent axon outgrowth and guidance.
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Affiliation(s)
- Judith Antoine-Bertrand
- From the Department of Anatomy and Cell Biology and Cancer Research Program, Research Institute of McGill University Health Centre, McGill University, Montreal, Quebec, H4A 3J1 Canada and
| | - Philippe M Duquette
- From the Department of Anatomy and Cell Biology and Cancer Research Program, Research Institute of McGill University Health Centre, McGill University, Montreal, Quebec, H4A 3J1 Canada and
| | - Ricardo Alchini
- the Department of Neurology and Neurosurgery, Montreal Neurological Institute, Montreal, Quebec, H3A 2B4 Canada
| | - Timothy E Kennedy
- the Department of Neurology and Neurosurgery, Montreal Neurological Institute, Montreal, Quebec, H3A 2B4 Canada
| | - Alyson E Fournier
- the Department of Neurology and Neurosurgery, Montreal Neurological Institute, Montreal, Quebec, H3A 2B4 Canada
| | - Nathalie Lamarche-Vane
- From the Department of Anatomy and Cell Biology and Cancer Research Program, Research Institute of McGill University Health Centre, McGill University, Montreal, Quebec, H4A 3J1 Canada and
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17
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Loyer N, Kolotuev I, Pinot M, Le Borgne R. Drosophila E-cadherin is required for the maintenance of ring canals anchoring to mechanically withstand tissue growth. Proc Natl Acad Sci U S A 2015; 112:12717-22. [PMID: 26424451 PMCID: PMC4611665 DOI: 10.1073/pnas.1504455112] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Intercellular bridges called "ring canals" (RCs) resulting from incomplete cytokinesis play an essential role in intercellular communication in somatic and germinal tissues. During Drosophila oogenesis, RCs connect the maturing oocyte to nurse cells supporting its growth. Despite numerous genetic screens aimed at identifying genes involved in RC biogenesis and maturation, how RCs anchor to the plasma membrane (PM) throughout development remains unexplained. In this study, we report that the clathrin adaptor protein 1 (AP-1) complex, although dispensable for the biogenesis of RCs, is required for the maintenance of the anchorage of RCs to the PM to withstand the increased membrane tension associated with the exponential tissue growth at the onset of vitellogenesis. Here we unravel the mechanisms by which AP-1 enables the maintenance of RCs' anchoring to the PM during size expansion. We show that AP-1 regulates the localization of the intercellular adhesion molecule E-cadherin and that loss of AP-1 causes the disappearance of the E-cadherin-containing adhesive clusters surrounding the RCs. E-cadherin itself is shown to be required for the maintenance of the RCs' anchorage, a function previously unrecognized because of functional compensation by N-cadherin. Scanning block-face EM combined with transmission EM analyses reveals the presence of interdigitated, actin- and Moesin-positive, microvilli-like structures wrapping the RCs. Thus, by modulating E-cadherin trafficking, we show that the sustained E-cadherin-dependent adhesion organizes the microvilli meshwork and ensures the proper attachment of RCs to the PM, thereby counteracting the increasing membrane tension induced by exponential tissue growth.
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Affiliation(s)
- Nicolas Loyer
- CNRS, UMR 6290, F-35000 Rennes, France; Institut de Génétique et Développement de Rennes, Université Rennes 1, F-35000 Rennes, France; Equipe Labellisée Ligue Nationale Contre le Cancer, F-35000 Rennes, France
| | - Irina Kolotuev
- CNRS, UMR 6290, F-35000 Rennes, France; Institut de Génétique et Développement de Rennes, Université Rennes 1, F-35000 Rennes, France; Equipe Labellisée Ligue Nationale Contre le Cancer, F-35000 Rennes, France; CNRS, Structure Fédérative de Recherche BIOSIT, Microscopy Rennes Imaging Center-Electron Microscopy Facility, F-35000 Rennes, France
| | - Mathieu Pinot
- CNRS, UMR 6290, F-35000 Rennes, France; Institut de Génétique et Développement de Rennes, Université Rennes 1, F-35000 Rennes, France; Equipe Labellisée Ligue Nationale Contre le Cancer, F-35000 Rennes, France
| | - Roland Le Borgne
- CNRS, UMR 6290, F-35000 Rennes, France; Institut de Génétique et Développement de Rennes, Université Rennes 1, F-35000 Rennes, France; Equipe Labellisée Ligue Nationale Contre le Cancer, F-35000 Rennes, France;
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18
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Hirashima T, Adachi T. Procedures for the quantification of whole-tissue immunofluorescence images obtained at single-cell resolution during murine tubular organ development. PLoS One 2015; 10:e0135343. [PMID: 26258587 PMCID: PMC4530862 DOI: 10.1371/journal.pone.0135343] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 07/21/2015] [Indexed: 11/19/2022] Open
Abstract
Whole-tissue quantification at single-cell resolution has become an inevitable approach for further quantitative understanding of morphogenesis in organ development. The feasibility of the approach has been dramatically increased by recent technological improvements in optical tissue clearing and microscopy. However, the series of procedures required for this approach to lead to successful whole-tissue quantification is far from developed. To provide the appropriate procedure, we here show tips for each critical step of the entire process, including fixation for immunofluorescence, optical clearing, and digital image processing, using developing murine internal organs such as epididymis, kidney, and lung as an example. Through comparison of fixative solutions and of clearing methods, we found optimal conditions to achieve clearer deep-tissue imaging of specific immunolabeled targets and explain what methods result in vivid volume imaging. In addition, we demonstrated that three-dimensional digital image processing after optical clearing produces objective quantitative data for the whole-tissue analysis, focusing on the spatial distribution of mitotic cells in the epididymal tubule. The procedure for the whole-tissue quantification shown in this article should contribute to systematic measurements of cellular processes in developing organs, accelerating the further understanding of morphogenesis at the single cell level.
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Affiliation(s)
- Tsuyoshi Hirashima
- Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan
- * E-mail:
| | - Taiji Adachi
- Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan
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19
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Fan G, Aleem S, Yang M, Miller WT, Tonks NK. Protein-tyrosine Phosphatase and Kinase Specificity in Regulation of SRC and Breast Tumor Kinase. J Biol Chem 2015; 290:15934-47. [PMID: 25897081 DOI: 10.1074/jbc.m115.651703] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Indexed: 11/06/2022] Open
Abstract
Despite significant evidence to the contrary, the view that phosphatases are "nonspecific" still pervades the field. Systems biology approaches to defining how signal transduction pathways are integrated at the level of whole organisms also often downplay the contribution of phosphatases, defining them as "erasers" that serve merely to restore the system to its basal state. Here, we present a study that counteracts the idea of "nonspecific phosphatases." We have characterized two structurally similar and functionally related kinases, BRK and SRC, which are regulated by combinations of activating autophosphorylation and inhibitory C-terminal sites of tyrosine phosphorylation. We demonstrated specificity at the level of the kinases in that SRMS phosphorylated the C terminus of BRK, but not SRC; in contrast, CSK is the kinase responsible for C-terminal phosphorylation of SRC, but not BRK. For the phosphatases, we observed that RNAi-mediated suppression of PTP1B resulted in opposing effects on the activity of BRK and SRC and have defined the mechanisms underlying this specificity. PTP1B inhibited BRK by directly dephosphorylating the Tyr-342 autophosphorylation site. In contrast, PTP1B potentiated SRC activity, but not by dephosphorylating SRC itself directly; instead, PTP1B regulated the interaction between CBP/PAG and CSK. SRC associated with, and phosphorylated, the transmembrane protein CBP/PAG at Tyr-317, resulting in CSK recruitment. We identified PAG as a substrate of PTP1B, and dephosphorylation abolished recruitment of the inhibitory kinase CSK. Overall, these findings illustrate how the combinatorial effects of PTKs and PTPs may be integrated to regulate signaling, with both classes of enzymes displaying exquisite specificity.
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Affiliation(s)
- Gaofeng Fan
- From the Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724-2208 and
| | - Saadat Aleem
- the Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York 11794-8661
| | - Ming Yang
- From the Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724-2208 and
| | - W Todd Miller
- the Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York 11794-8661
| | - Nicholas K Tonks
- From the Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724-2208 and
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20
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Kohno T, Ninomiya T, Kikuchi S, Konno T, Kojima T. Staurosporine induces formation of two types of extra-long cell protrusions: actin-based filaments and microtubule-based shafts. Mol Pharmacol 2015; 87:815-24. [PMID: 25680752 DOI: 10.1124/mol.114.096982] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Staurosporine (STS) has been known as a classic protein kinase C inhibitor and is a broad-spectrum inhibitor targeting over 250 protein kinases. In this study, we observed that STS treatment induced drastic morphologic changes, such as elongation of a very large number of nonbranched, actin-based long cell protrusions that reached up to 30 µm in an hour without caspase activation or PARP cleavage in fibroblasts and epithelial cells. These cell protrusions were elongated not only from the free cell edge but also from the cell-cell junctions. The elongation of STS-dependent protrusions was required for ATP hydrolysis and was dependent on myosin-X and fascin but independent of Cdc42 and VASP. Interestingly, in the presence of an actin polymerization inhibitor, namely, cytochalasin D, latrunculin A, or jasplakinolide, STS treatment induced excess tubulin polymerization, which resulted in the formation of many extra-long microtubule (MT)-based protrusions toward the outside of the cell. The unique MT-based protrusions were thick and linear compared with the STS-induced filaments or stationary filopodia. These protrusions, which were composed of microtubules, have been scarcely observed in cultured non-neuronal cells. Taken together, our findings revealed that STS-sensitive kinases are essential for the maintenance of normal cell morphology, and a common unidentified molecular mechanism is involved in the formation of the following two different types of protrusions: actin-based filaments and MT-based shafts.
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Affiliation(s)
- Takayuki Kohno
- Department of Cell Science, Research Institute for Frontier Medicine (T.Koh., T.Kon., T.Koj.), and Department of Anatomy, Sapporo Medical University, Sapporo, Japan (T.N., S.K.)
| | - Takafumi Ninomiya
- Department of Cell Science, Research Institute for Frontier Medicine (T.Koh., T.Kon., T.Koj.), and Department of Anatomy, Sapporo Medical University, Sapporo, Japan (T.N., S.K.)
| | - Shin Kikuchi
- Department of Cell Science, Research Institute for Frontier Medicine (T.Koh., T.Kon., T.Koj.), and Department of Anatomy, Sapporo Medical University, Sapporo, Japan (T.N., S.K.)
| | - Takumi Konno
- Department of Cell Science, Research Institute for Frontier Medicine (T.Koh., T.Kon., T.Koj.), and Department of Anatomy, Sapporo Medical University, Sapporo, Japan (T.N., S.K.)
| | - Takashi Kojima
- Department of Cell Science, Research Institute for Frontier Medicine (T.Koh., T.Kon., T.Koj.), and Department of Anatomy, Sapporo Medical University, Sapporo, Japan (T.N., S.K.)
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21
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Miyauchi T, Yamamoto H, Abe Y, Yoshida GJ, Rojek A, Sohara E, Uchida S, Nielsen S, Yasui M. Dynamic subcellular localization of aquaporin-7 in white adipocytes. FEBS Lett 2015; 589:608-14. [PMID: 25643985 DOI: 10.1016/j.febslet.2015.01.025] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 12/15/2014] [Accepted: 01/15/2015] [Indexed: 01/14/2023]
Abstract
Aquaporin-7 (AQP7) is expressed in adipose tissue, permeated by water and glycerol, and is involved in lipid metabolism. AQP7-null mice develop obesity, insulin resistance, and adipocyte hypertrophy. Here, we show that AQP7 is expressed in adipocyte plasma membranes, and is re-localized to intracellular membranes in response to catecholamine in mouse white adipose tissue. We found that internalization of AQP7 was induced by PKA activation and comparative gene identification 58 (CGI-58). This relocation was confirmed by functional studies in 3T3-L1 adipocytes. Collectively, these results suggest that AQP7 makes several contributions to adipocyte metabolism, in both cortical and intracellular membranes.
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Affiliation(s)
- Takayuki Miyauchi
- Department of Pharmacology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan.
| | - Hiroyuki Yamamoto
- Department of Pharmacology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
| | - Yoichiro Abe
- Department of Pharmacology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
| | - Go J Yoshida
- Department of Pharmacology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
| | - Aleksandra Rojek
- Department of Health Science and Technology, Aalborg University, Fredrik Bajersvej 7, 9220 Aalborg, Denmark
| | - Eisei Sohara
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Yushima, Bunkyo, Tokyo 113-8519, Japan
| | - Shinichi Uchida
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Yushima, Bunkyo, Tokyo 113-8519, Japan
| | - Søren Nielsen
- Department of Health Science and Technology, Aalborg University, Fredrik Bajersvej 7, 9220 Aalborg, Denmark
| | - Masato Yasui
- Department of Pharmacology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan.
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22
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Kravtsov D, Mashukova A, Forteza R, Rodriguez MM, Ameen NA, Salas PJ. Myosin 5b loss of function leads to defects in polarized signaling: implication for microvillus inclusion disease pathogenesis and treatment. Am J Physiol Gastrointest Liver Physiol 2014; 307:G992-G1001. [PMID: 25258405 PMCID: PMC4233287 DOI: 10.1152/ajpgi.00180.2014] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Microvillus inclusion disease (MVID) is an autosomal recessive condition resulting in intractable secretory diarrhea in newborns due to loss-of-function mutations in myosin Vb (Myo5b). Previous work suggested that the apical recycling endosomal (ARE) compartment is the primary location for phosphoinositide-dependent protein kinase 1 (PDK1) signaling. Because the ARE is disrupted in MVID, we tested the hypothesis that polarized signaling is affected by Myo5b dysfunction. Subcellular distribution of PDK1 was analyzed in human enterocytes from MVID/control patients by immunocytochemistry. Using Myo5b knockdown (kd) in Caco-2BBe cells, we studied phosphorylated kinases downstream of PDK1, electrophysiological parameters, and net water flux. PDK1 was aberrantly localized in human MVID enterocytes and Myo5b-deficient Caco-2BBe cells. Two PDK1 target kinases were differentially affected: phosphorylated atypical protein kinase C (aPKC) increased fivefold and phosohoprotein kinase B slightly decreased compared with control. PDK1 redistributed to a soluble (cytosolic) fraction and copurified with basolateral endosomes in Myo5b kd. Myo5b kd cells showed a decrease in net water absorption that could be reverted with PDK1 inhibitors. We conclude that, in addition to altered apical expression of ion transporters, depolarization of PDK1 in MVID enterocytes may lead to aberrant activation of downstream kinases such as aPKC. The findings in this work suggest that PDK1-dependent signaling may provide a therapeutic target for treating MVID.
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Affiliation(s)
- Dmitri Kravtsov
- 1Department of Pediatrics, Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut;
| | - Anastasia Mashukova
- 2Department of Physiology, Nova Southeastern University, Ft. Lauderdale, Florida; ,3Department of Cell Biology, University of Miami Miller School of Medicine, Miami, Florida; and
| | - Radia Forteza
- 3Department of Cell Biology, University of Miami Miller School of Medicine, Miami, Florida; and
| | - Maria M. Rodriguez
- 4Department of Pathology, University of Miami Miller School of Medicine, Miami, Florida
| | - Nadia A. Ameen
- 1Department of Pediatrics, Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut;
| | - Pedro J. Salas
- 3Department of Cell Biology, University of Miami Miller School of Medicine, Miami, Florida; and
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23
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Yonemura S. Differential sensitivity of epithelial cells to extracellular matrix in polarity establishment. PLoS One 2014; 9:e112922. [PMID: 25393292 PMCID: PMC4231087 DOI: 10.1371/journal.pone.0112922] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 10/16/2014] [Indexed: 11/18/2022] Open
Abstract
Establishment of apical-basal polarity is crucial for epithelial sheets that form a compartment in the body, which function to maintain the environment in the compartment. Effects of impaired polarization are easily observed in three-dimensional (3-D) culture systems rather than in two-dimensional (2-D) culture systems. Although the mechanisms for establishing the polarity are not completely understood, signals from the extracellular matrix (ECM) are considered to be essential for determining the basal side and eventually generating polarity in the epithelial cells. To elucidate the common features and differences in polarity establishment among various epithelial cells, we analyzed the formation of epithelial apical-basal polarity using three cell lines of different origin: MDCK II cells (dog renal tubules), EpH4 cells (mouse mammary gland), and R2/7 cells (human colon) expressing wild-type α-catenin (R2/7 α-Cate cells). These cells showed clear apical-basal polarity in 2-D cultures. In 3-D cultures, however, each cell line displayed different responses to the same ECM. In MDCK II cells, spheroids with a single lumen formed in both Matrigel and collagen gel. In R2/7 α-Cate cells, spheroids showed similar apical-basal polarity as that seen in MDCK II cells, but had multiple lumens. In EpH4 cells, the spheroids displayed an apical-basal polarity that was opposite to that seen in the other two cell types in both ECM gels, at least during the culture period. On the other hand, the three cell lines showed the same apical-basal polarity both in 2-D cultures and in 3-D cultures using the hanging drop method. The three lines also had similar cellular responses to ECM secreted by the cells themselves. Therefore, appropriate culture conditions should be carefully determined in advance when using various epithelial cells to analyze cell polarity or 3-D morphogenesis.
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Affiliation(s)
- Shigenobu Yonemura
- Electron Microscope Laboratory, RIKEN Center for Developmental Biology, Kobe, Hyogo, Japan
- CREST, Japan Science and Technology Agency, Kobe, Hyogo, Japan
- * E-mail:
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Manukyan A, Ludwig K, Sanchez-Manchinelly S, Parsons SJ, Stukenberg PT. A complex of p190RhoGAP-A and anillin modulates RhoA-GTP and the cytokinetic furrow in human cells. J Cell Sci 2014; 128:50-60. [PMID: 25359885 DOI: 10.1242/jcs.151647] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The cytokinetic furrow is organized by the RhoA GTPase, which recruits actin and myosin II to the furrow and drives contractility. Here, we show that the RhoA GTPase-activting protein (GAP) p190RhoGAP-A (also known as ARHGAP35) has a role in cytokinesis and is involved in regulating levels of RhoA-GTP and contractility. Cells depleted of p190RhoGAP-A accumulate high levels of RhoA-GTP and markers of high RhoA activity in the furrow, resulting in failure of the cytokinetic furrow to progress to abscission. The loss of p190RhoGAP-A can be rescued by a low dose of the myosin II inhibitor blebbistatin, suggesting that cells fail cytokinesis because they have too much myosin activity. p190RhoGAP-A binds the cytokinetic organizer anillin, and mutants of p190RhoGAP-A that are unable to bind anillin or unable to inactivate RhoA fail to rescue cytokinesis defects in p190RhoGAP-A-depleted cells. Taken together, these data demonstrate that a complex of p190RhoGAP-A and anillin modulates RhoA-GTP levels in the cytokinetic furrow to ensure progression of cytokinesis.
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Affiliation(s)
- Arkadi Manukyan
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, PO Box 800733, Charlottesville, VA 22908, USA Cancer Center, University of Virginia School of Medicine, PO Box 800733, Charlottesville, VA 22908, USA
| | - Kirsten Ludwig
- Cancer Center, University of Virginia School of Medicine, PO Box 800733, Charlottesville, VA 22908, USA Department of Psychiatry and Behavioral Sciences and Jonsson Cancer Center, UCLA, Los Angeles, CA 90095-6900, USA Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, PO Box 800733, Charlottesville, VA 22908, USA
| | - Sergio Sanchez-Manchinelly
- Cancer Center, University of Virginia School of Medicine, PO Box 800733, Charlottesville, VA 22908, USA Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, PO Box 800733, Charlottesville, VA 22908, USA Beckman Corporation, Los Angeles, CA 90025, USA
| | - Sarah J Parsons
- Cancer Center, University of Virginia School of Medicine, PO Box 800733, Charlottesville, VA 22908, USA Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, PO Box 800733, Charlottesville, VA 22908, USA
| | - P Todd Stukenberg
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, PO Box 800733, Charlottesville, VA 22908, USA Cancer Center, University of Virginia School of Medicine, PO Box 800733, Charlottesville, VA 22908, USA
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25
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Al-Momany A, Li L, Alexander RT, Ballermann BJ. Clustered PI(4,5)P₂ accumulation and ezrin phosphorylation in response to CLIC5A. J Cell Sci 2014; 127:5164-78. [PMID: 25344252 DOI: 10.1242/jcs.147744] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
CLIC5A (encoded by CLIC5) is a component of the ezrin-NHERF2-podocalyxin complex in renal glomerular podocyte foot processes. We explored the mechanism(s) by which CLIC5A regulates ezrin function. In COS-7 cells, CLIC5A augmented ezrin phosphorylation without changing ezrin abundance, increased the association of ezrin with the cytoskeletal fraction and enhanced actin polymerization and the formation of cell surface projections. CLIC5A caused the phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] reporter RFP-PH-PLC to translocate from the cytosol to discrete plasma membrane clusters at the cell surface, where it colocalized with CLIC5A. Transiently expressed HA-PIP5Kα colocalized with GFP-CLIC5A and was pulled from cell lysates by GST-CLIC5A, and silencing of endogenous PIP5Kα abrogated CLIC5A-dependent ERM phosphorylation. N- and C-terminal deletion mutants of CLIC5A, which failed to associate with the plasma membrane, failed to colocalize with PIP5Kα, did not alter the abundance of PI(4,5)P2 plasma membrane clusters and failed to enhance ezrin phosphorylation. Relative to wild-type mice, in CLIC5-deficient mice, the phosphorylation of glomerular ezrin was diminished and the cytoskeletal association of both ezrin and NHERF2 was reduced. Therefore, the mechanism of CLIC5A action involves clustered plasma membrane PI(4,5)P2 accumulation through an interaction of CLIC5A with PI(4,5)P2-generating kinases, in turn facilitating ezrin activation and actin-dependent cell surface remodeling.
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Affiliation(s)
- Abass Al-Momany
- Department of Physiology, University of Alberta, Edmonton, AL T6G 2V2, Canada
| | - Laiji Li
- Department of Medicine (Nephrology), University of Alberta, Edmonton, AL T6G 2V2, Canada
| | - R Todd Alexander
- Department of Pediatrics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AL T6G 2V2, Canada
| | - Barbara J Ballermann
- Department of Physiology, University of Alberta, Edmonton, AL T6G 2V2, Canada Department of Medicine (Nephrology), University of Alberta, Edmonton, AL T6G 2V2, Canada
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26
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Wang P, Li M, Liu Q, Chen B, Ji Z. Detection of urinary podocytes and nephrin as markers for children with glomerular diseases. Exp Biol Med (Maywood) 2014; 240:169-74. [PMID: 25245074 DOI: 10.1177/1535370214548995] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The purpose of this study was to detect the urinary podocytes and its related protein, nephrin, in the urine of the children with glomerular disease in order to analyze the relationship of the clinical testing with the significance of the glomerular disease. A total of 65 children with nephrotic syndrome were selected for this study. The podocytes and nephrin were detected in the urinary sediment by indirect immunofluorescence, enzyme-linked immunosorbent assay, and Western blotting. The urinary podocytes and nephrin positive rates were 53.8% and 50.8%, respectively, in the children with glomerular disease. The serum total protein and albumin decreased in the podocyte-positive children, while the urine total protein at 24 h, urinary albumin/creatinine ratio, blood urea nitrogen, and serum creatinine were significantly elevated as compared to those of the podocyte-negative patients. Furthermore, the results were the same in the patients with positive nephrin as compared to that of the patients with negative nephrin. The podocyte number and nephrin level were significantly higher in the lupus nephritis group as compared to those of the other groups. Likewise, the podocyte number and nephrin level dramatically increased in the focal segmental glomerulosclerosis group as compared to those of the mesangial proliferative glomerulonephritis and minimal change disease groups. In addition, the podocyte numbers and nephrin expression were significantly higher in severe proteinuria group as compared to those of the mild proteinuria group. The urinary nephrin expression was positively related to podocyte and urinary albumin/creatinine ratio. We concluded that the detection of the urinary podocytes and nephrin could be taken as markers for children with glomerular disease, reflecting the type of the disease. Therefore, this can be used as a noninvasive method to evaluate the severity of the kidney disease in children.
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Affiliation(s)
- Pei Wang
- The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou 510182, China
| | - Min Li
- The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou 510182, China
| | - Qicai Liu
- The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou 510182, China
| | - Bo Chen
- The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou 510182, China
| | - Zequan Ji
- The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou 510182, China
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27
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Kitajiri SI, Katsuno T, Sasaki H, Ito J, Furuse M, Tsukita S. Deafness in occludin-deficient mice with dislocation of tricellulin and progressive apoptosis of the hair cells. Biol Open 2014; 3:759-66. [PMID: 25063198 PMCID: PMC4133728 DOI: 10.1242/bio.20147799] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Occludin is the first identified protein in the tight junction (TJ), but its function has remained for the most part obscure. TJs have been demonstrated to play important roles in the inner ear function, and occludin is expressed in all the epithelial TJs in the inner ear. Thus, we examined the inner ears of occludin-deficient (Occ−/−) mice. Although inner ears initially developed normally in Occ−/− mice, apoptosis occurs in hair cells in the organ of Corti around day 12 after birth, and deafness develops. Since hair cell degeneration was not observed in cochlear explant cultures of Occ−/− mice, environmental changes were considered to be the trigger of cell death. As for the vestibular system, both the morphologies and functions are normal in Occ−/− mice. These phenotypes of Occ−/− mice are very similar with those of claudin-14 or claudin-9 deficient mice, leading us to speculate on the existence of imbalance induced by TJ abnormalities, such as localized ionic components. Moreover, the occludin deficiency led to dislocalization of tricellulin, a gene responsible for human deafness DFNB49. The deafness in Occ−/− mice may be due to this dislocalization of tricellulin.
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Affiliation(s)
- Shin-Ichiro Kitajiri
- Department of Otolaryngology, Head and Neck Surgery, Kyoto University Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan Department of Cell Biology, Faculty of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Tatsuya Katsuno
- Department of Otolaryngology, Head and Neck Surgery, Kyoto University Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan
| | - Hiroyuki Sasaki
- Department of Physical Therapy, Faculty of Community Health Care, Teikyo Heisei University, Uruido Minami, Ichihara, Chiba 290-0193, Japan
| | - Juichi Ito
- Department of Otolaryngology, Head and Neck Surgery, Kyoto University Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan
| | - Mikio Furuse
- Department of Cell Biology, Division of Cell Biology, Kobe University Graduate School of Medicine, Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan Division of Cerebral Structure, National Institute for Physiological Sciences, Okazaki, 444-8787, Japan
| | - Shoichiro Tsukita
- Department of Cell Biology, Faculty of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
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28
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Alshafie W, Chappe FG, Li M, Anini Y, Chappe VM. VIP regulates CFTR membrane expression and function in Calu-3 cells by increasing its interaction with NHERF1 and P-ERM in a VPAC1- and PKCε-dependent manner. Am J Physiol Cell Physiol 2014; 307:C107-19. [DOI: 10.1152/ajpcell.00296.2013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Vasoactive intestinal peptide (VIP) is a topical airway gland secretagogue regulating fluid secretions, primarily by stimulating cystic fibrosis transmembrane conductance regulator (CFTR)-dependent chloride secretion that contributes to the airways innate defense mechanism. We previously reported that prolonged VIP stimulation of pituitary adenylate cyclase-activating peptide receptors (VPAC1) in airway cells enhances CFTR function by increasing its membrane stability. In the present study, we identified the key effectors in the VIP signaling cascade in the human bronchial serous cell line Calu-3. Using immunocytochemistry and in situ proximity ligation assays, we found that VIP stimulation increased CFTR membrane localization by promoting its colocalization and interaction with the scaffolding protein Na+/H+ exchange factor 1 (NHERF1), a PDZ protein known as a positive regulator for CFTR membrane localization. VIP stimulation also increased phosphorylation, by protein kinase Cε of the actin-binding protein complex ezrin/radixin/moesin (ERM) and its interaction with NHERF1 and CFTR complex. On the other hand, it reduced intracellular CFTR colocalization and interaction with CFTR associated ligand, another PDZ protein known to compete with NHERF1 for CFTR interaction, inducing cytoplasmic retention and lysosomal degradation. Reducing NHERF1 or ERM expression levels by specific siRNAs prevented the VIP effect on CFTR membrane stability. Furthermore, iodide efflux assays confirmed that NHERF1 and P-ERM are necessary for VIP regulation of the stability and sustained activity of membrane CFTR. This study shows the cellular mechanism by which prolonged VIP stimulation of airway epithelial cells regulates CFTR-dependent secretions.
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Affiliation(s)
- Walaa Alshafie
- Departments of Physiology and Biophysics, Dalhousie University, Nova Scotia, Canada and
| | - Frederic G. Chappe
- Departments of Physiology and Biophysics, Dalhousie University, Nova Scotia, Canada and
| | - Mansong Li
- Departments of Physiology and Biophysics, Dalhousie University, Nova Scotia, Canada and
| | - Younes Anini
- Departments of Physiology and Biophysics, Dalhousie University, Nova Scotia, Canada and
- Obstetrics and Gynecology, Dalhousie University, Nova Scotia, Canada
| | - Valerie M. Chappe
- Departments of Physiology and Biophysics, Dalhousie University, Nova Scotia, Canada and
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29
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Ibuprofen protects ventilator-induced lung injury by downregulating Rho-kinase activity in rats. BIOMED RESEARCH INTERNATIONAL 2014; 2014:749097. [PMID: 25019086 PMCID: PMC4075182 DOI: 10.1155/2014/749097] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2014] [Revised: 05/15/2014] [Accepted: 05/19/2014] [Indexed: 12/20/2022]
Abstract
Background. Ventilator-induced lung injury-(VILI-) induced endothelial permeability is regulated through the Rho-dependent signaling pathway. Ibuprofen inhibits Rho activation in animal models of spinal-cord injury and Alzheimer's disease. The study aims to investigate ibuprofen effects on high tidal volume associated VILI. Methods. Twenty-eight adult male Sprague-Dawley rats were randomized to receive a ventilation strategy with three different interventions for 2 h: (1) a high-volume zero-positive end-expiratory pressure (PEEP) (HVZP) group; (2) an HVZP + ibuprofen 15 mg/kg group; and (3) an HVZP + ibuprofen 30 mg/kg group. A fourth group without ventilation served as the control group. Rho-kinase activity was determined by ratio of phosphorylated ezrin, radixin, and moesin (p-ERM), substrates of Rho-kinase, to total ERM. VILI was characterized by increased pulmonary protein leak, wet-to-dry weight ratio, cytokines level, and Rho guanine nucleotide exchange factor (GEF-H1), RhoA activity, p-ERM/total ERM, and p-myosin light chain (MLC) protein expression. Results. Ibuprofen pretreatment significantly reduced the HVZP ventilation-induced increase in pulmonary protein leak, wet-to-dry weight ratio, bronchoalveolar lavage fluid interleukin-6 and RANTES levels, and lung GEF-H1, RhoA activity, p-ERM/total ERM, and p-MLC protein expression. Conclusion. Ibuprofen attenuated high tidal volume induced pulmonary endothelial hyperpermeability. This protective effect was associated with a reduced Rho-kinase activity.
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30
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Mashukova A, Kozhekbaeva Z, Forteza R, Dulam V, Figueroa Y, Warren R, Salas PJ. The BAG-1 isoform BAG-1M regulates keratin-associated Hsp70 chaperoning of aPKC in intestinal cells during activation of inflammatory signaling. J Cell Sci 2014; 127:3568-77. [PMID: 24876225 DOI: 10.1242/jcs.151084] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Atypical PKC (ι/λ and ζ; hereafter referred to as aPKC) is a key player in the acquisition of epithelial polarity and participates in other signaling cascades including the control of NF-κB signaling. This kinase is post-translationally regulated through Hsp70-mediated refolding. Previous work has shown that such a chaperoning activity is specifically localized to keratin intermediate filaments. Our work was performed with the goal of identifying the molecule(s) that block Hsp70 activity on keratin filaments during inflammation. A transcriptional screen allowed us to focus on BAG-1, a multi-functional protein that assists Hsp70 in nucleotide exchange but also blocks its activity at higher concentrations. We found the BAG-1 isoform BAG-1M upregulated threefold in human Caco-2 cells following stimulation with tumor necrosis factor receptor α (TNFα) to induce a pro-inflammatory response, and up to sixfold in mouse enterocytes following treatment with dextran sodium sulfate (DSS) to induce colitis. BAG-1M, but no other isoform, was found to co-purify with intermediate filaments and block Hsp70 activity in the keratin fraction but not in the soluble fraction within the range of concentrations found in epithelial cells cultured under control and inflammation conditions. Constitutive expression of BAG-1M decreased levels of phosphorylated aPKC. By contrast, knockdown of BAG-1, blocked the TNFα-induced decrease of phosphorylated aPKC. We conclude that BAG-1M mediates Hsp70 inhibition downstream of NF-κB.
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Affiliation(s)
- Anastasia Mashukova
- Nova Southeastern University, Department of Physiology, Fort Lauderdale, FL 33314, USA University of Miami Miller School of Medicine, Department of Cell Biology, Miami, FL 33136, USA
| | - Zhanna Kozhekbaeva
- University of Miami Miller School of Medicine, Department of Cell Biology, Miami, FL 33136, USA
| | - Radia Forteza
- University of Miami Miller School of Medicine, Department of Cell Biology, Miami, FL 33136, USA
| | - Vipin Dulam
- University of Miami Miller School of Medicine, Department of Cell Biology, Miami, FL 33136, USA
| | - Yolanda Figueroa
- University of Miami Miller School of Medicine, Department of Cell Biology, Miami, FL 33136, USA
| | - Robert Warren
- University of Miami Miller School of Medicine, Department of Cell Biology, Miami, FL 33136, USA
| | - Pedro J Salas
- University of Miami Miller School of Medicine, Department of Cell Biology, Miami, FL 33136, USA
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31
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Khasnis M, Nakatomi A, Gumpper K, Eto M. Reconstituted human myosin light chain phosphatase reveals distinct roles of two inhibitory phosphorylation sites of the regulatory subunit, MYPT1. Biochemistry 2014; 53:2701-9. [PMID: 24712327 PMCID: PMC4010256 DOI: 10.1021/bi5001728] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
![]()
The myosin light chain phosphatase
(MLCP) is a cytoskeleton-associated
protein phosphatase-1 (PP1) holoenzyme and a RhoA/ROCK effector, regulating
cytoskeletal reorganization. ROCK-induced phosphorylation of the MLCP
regulatory subunit (MYPT1) at two sites, Thr696 and Thr853, suppresses
the activity, although little is known about the difference in the
role. Here, we developed a new method for the preparation of the recombinant
human MLCP complex and determined the molecular and cellular basis
of inhibitory phosphorylation. The recombinant MLCP partially purified
from mammalian cell lysates retained characteristics of the native
enzyme, such that it was fully active without Mn2+ and
sensitive to PP1 inhibitor compounds. Selective thio-phosphorylation
of MYPT1 at Thr696 with ROCK inhibited the MLCP activity 30%, whereas
the Thr853 thio-phosphorylation did not alter the phosphatase activity.
Interference with the docking of phospho-Thr696 at the active site
weakened the inhibition, suggesting selective autoinhibition induced
by phospho-Thr696. Both Thr696 and Thr853 sites underwent autodephosphorylation.
Compared with that of Thr853, phosphorylation of Thr696 was more stable,
and it facilitated Thr853 phosphorylation. Endogenous MYPT1 at Thr696
was spontaneously phosphorylated in quiescent human leiomyosarcoma
cells. Serum stimulation of the cells resulted in dissociation of
MYPT1 from myosin and PP1C in parallel with an increase in the level
of Thr853 phosphorylation. The C-terminal domain of human MYPT1(495–1030)
was responsible for the binding to the N-terminal portion of myosin
light meromyosin. The spontaneous phosphorylation at Thr696 may adjust
the basal activity of cellular MLCP and affect the temporal phosphorylation
at Thr853 that is synchronized with myosin targeting.
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Affiliation(s)
- Mukta Khasnis
- Department of Molecular Physiology and Biophysics, Thomas Jefferson University Jefferson Medical School , and Kimmel Cancer Center , 1020 Locust Street, Philadelphia, Pennsylvania 19107, United States
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32
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Ramadhanti J, Huang P, Kusano-Arai O, Iwanari H, Sakihama T, Misu T, Fujihara K, Hamakubo T, Yasui M, Abe Y. A novel monoclonal antibody against the C-terminal region of aquaporin-4. Monoclon Antib Immunodiagn Immunother 2014; 32:270-6. [PMID: 23909421 DOI: 10.1089/mab.2013.0007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Aquaporin-4 (AQP4), the most abundant water channel in the brain, plays a central role in water homeostasis, neuronal activity, and migration of astrocytes in the central nervous system. Recent studies have demonstrated that AQP4 is a target of an autoantibody specifically detected in an autoimmune neurologic disease called neuromyelitis optica. Here we have generated a monoclonal antibody (MAb) against the C-terminal region of AQP4 using a baculovirus expressing mouse AQP4 as an immunogen. This antibody (clone E5206) recognized both human and mouse AQP4s in a denaturing condition and was able to precipitate AQP4 from cell lysates of CHO cells stably expressing AQP4. Western blot analysis using deletion mutants revealed that the epitope was located within a region between Asp(303) and Leu(320) in the C-terminal tail of AQP4. Although clone E5206 could not be used for immunostaining when cells or tissues were fixed with 4% paraformaldehyde or 10% formalin, it could be used when cells were fixed with 10% trichloroacetic acid and when a formalin-fixed tissue section was pretreated with antigen-retrieval reagents. This MAb can be a valuable tool for analysis of AQP4 in a variety of physiological and pathophysiological contexts, in human tissues and organs as well as in rodent models, both in vitro and in vivo.
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Affiliation(s)
- Julia Ramadhanti
- Department of Pharmacology, School of Medicine, Keio University, Shinjyuku-ku, Tokyo, Japan
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33
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Ueyama T, Sakaguchi H, Nakamura T, Goto A, Morioka S, Shimizu A, Nakao K, Hishikawa Y, Ninoyu Y, Kassai H, Suetsugu S, Koji T, Fritzsch B, Yonemura S, Hisa Y, Matsuda M, Aiba A, Saito N. Maintenance of stereocilia and apical junctional complexes by Cdc42 in cochlear hair cells. J Cell Sci 2014; 127:2040-52. [PMID: 24610943 DOI: 10.1242/jcs.143602] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Cdc42 is a key regulator of dynamic actin organization. However, little is known about how Cdc42-dependent actin regulation influences steady-state actin structures in differentiated epithelia. We employed inner ear hair-cell-specific conditional knockout to analyze the role of Cdc42 in hair cells possessing highly elaborate stable actin protrusions (stereocilia). Hair cells of Atoh1-Cre;Cdc42(flox/flox) mice developed normally but progressively degenerated after maturation, resulting in progressive hearing loss particularly at high frequencies. Cochlear hair cell degeneration was more robust in inner hair cells than in outer hair cells, and began as stereocilia fusion and depletion, accompanied by a thinning and waving circumferential actin belt at apical junctional complexes (AJCs). Adenovirus-encoded GFP-Cdc42 expression in hair cells and fluorescence resonance energy transfer (FRET) imaging of hair cells from transgenic mice expressing a Cdc42-FRET biosensor indicated Cdc42 presence and activation at stereociliary membranes and AJCs in cochlear hair cells. Cdc42-knockdown in MDCK cells produced phenotypes similar to those of Cdc42-deleted hair cells, including abnormal microvilli and disrupted AJCs, and downregulated actin turnover represented by enhanced levels of phosphorylated cofilin. Thus, Cdc42 influenced the maintenance of stable actin structures through elaborate tuning of actin turnover, and maintained function and viability of cochlear hair cells.
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Affiliation(s)
- Takehiko Ueyama
- Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe 657-8501, Japan
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Renshaw MJ, Liu J, Lavoie BD, Wilde A. Anillin-dependent organization of septin filaments promotes intercellular bridge elongation and Chmp4B targeting to the abscission site. Open Biol 2014; 4:130190. [PMID: 24451548 PMCID: PMC3909275 DOI: 10.1098/rsob.130190] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The final step of cytokinesis is abscission when the intercellular bridge (ICB) linking the two new daughter cells is broken. Correct construction of the ICB is crucial for the assembly of factors involved in abscission, a failure in which results in aneuploidy. Using live imaging and subdiffraction microscopy, we identify new anillin–septin cytoskeleton-dependent stages in ICB formation and maturation. We show that after the formation of an initial ICB, septin filaments drive ICB elongation during which tubules containing anillin–septin rings are extruded from the ICB. Septins then generate sites of further constriction within the mature ICB from which they are subsequently removed. The action of the anillin–septin complex during ICB maturation also primes the ICB for the future assembly of the ESCRT III component Chmp4B at the abscission site. These studies suggest that the sequential action of distinct contractile machineries coordinates the formation of the abscission site and the successful completion of cytokinesis.
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Affiliation(s)
- Matthew J Renshaw
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
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35
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Goto H, Inagaki M. Method for the generation of antibodies specific for site and posttranslational modifications. Methods Mol Biol 2014; 1131:21-31. [PMID: 24515457 DOI: 10.1007/978-1-62703-992-5_2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Protein phosphorylation plays critical roles in multiple aspects of cellular events. Site- and phosphorylation state-specific antibodies are indispensable to analyze spatially and temporally distribution of protein phosphorylation in cells. Such information provides some clues of its biological function. Here, we describe a strategy to design a phosphopeptide as an antigen for a site- and phosphorylation state-specific antibody. Importantly, this strategy is also applicable to the production of other types of antibodies, which specifically recognize the site-specific modification, such as acetylation, methylation, and proteolysis. This protocol also focuses on the screening for monoclonal version of a site- and phosphorylation state-specific antibody.
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Affiliation(s)
- Hidemasa Goto
- Aichi Cancer Center Research Institute, Nagoya, Aichi, Japan
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Nakano T, Sekine S, Ito K, Horie T. Ezrin regulates the expression of Mrp2/Abcc2 and Mdr1/Abcb1 along the rat small intestinal tract. Am J Physiol Gastrointest Liver Physiol 2013; 305:G807-17. [PMID: 24091598 DOI: 10.1152/ajpgi.00187.2013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Multidrug resistance-associated protein 2 (MRP2)/ATP-binding cassette protein C2 (ABCC2) and multidrug resistance protein 1 (MDR1)/ABCB1 are well-known efflux transporters located on the brush border membrane of the small intestinal epithelia, where they limit the absorption of a broad range of substrates. The expression patterns of MRP2/ABCC2 and MDR1/ABCB1 along the small intestinal tract are tightly regulated. Several reports have demonstrated the participation of ERM (ezrin/radixin/moesin) proteins in the posttranslational modulation of MRP2/ABCC2 and MDR1/ABCB1, especially with regard to their membrane localization. The present study focused on the in vivo expression profiles of MRP2/ABCC2, MDR1/ABCB1, ezrin, and phosphorylated ezrin to further elucidate the relationship between the efflux transporters and the ERM proteins. The current results showed good correlation between the phosphorylation status of ezrin and Mrp2/Abcc2 expression along the gastrointestinal tract of rats and between the expression profiles of both ezrin and Mdr1/Abcb1 in the small intestine. We also demonstrated the involvement of conventional protein kinase C isoforms in the regulation of ezrin phosphorylation. Furthermore, experiments conducted with wild-type (WT) ezrin and a T567A (Ala substituted Thr) dephosphorylated mutant showed a decrease in membrane surface-localized and total expressed MRP2/ABCC2 in T567A-expressing vs. WT ezrin-expressing Caco-2 cells. In contrast, T567A- and WT-expressing cells both showed an increase in membrane surface-localized and total expressed MDR1/ABCB1. These findings suggest that the phosphorylation status and the expression profile of ezrin differentially direct MRP2/ABCC2 and MDR1/ABCB1 expression, respectively, along the small intestinal tract.
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Affiliation(s)
- Takafumi Nakano
- Faculty of Pharmaceutical Sciences, Teikyo Heisei University, 4-21-2 Nakano, Nakano-ku, Tokyo 164-8530, Japan.
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Yao R, Kondoh Y, Natsume Y, Yamanaka H, Inoue M, Toki H, Takagi R, Shimizu T, Yamori T, Osada H, Noda T. A small compound targeting TACC3 revealed its different spatiotemporal contributions for spindle assembly in cancer cells. Oncogene 2013; 33:4242-52. [PMID: 24077290 DOI: 10.1038/onc.2013.382] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 07/17/2013] [Accepted: 08/09/2013] [Indexed: 12/21/2022]
Abstract
The mitotic spindle is assembled by the coordinated action of centrosomes and kinetochore microtubules. An evolutionally conserved protein family, transforming acidic coiled-coil (TACC), has been shown to be involved in this process. In humans, TACC3 is aberrantly expressed in a variety of human cancers, but its biological significance remains to be elucidated. Here, using a novel compound targeting TACC3, spindlactone (SPL), we show that the perturbation of TACC3 selectively inhibited the nucleation of centrosome microtubules in ovarian cancer cells. In contrast to centrosome microtubules, the kinetochore microtubules were robustly assembled, forming ectopic spindle poles that resulted in multipolar spindles. Interestingly, the extensive inhibition of TACC3 partially suppressed the nucleation of kinetochore microtubules. These dose-dependent effects of SPL were consistent with the results observed by the depletion of TACC3 and its binding partner, colonic and hepatic tumor overexpressed gene protein (TOGp). Although these proteins both have roles in the assembly of centrosome and kinetochore microtubules, their contributions were spatiotemporally different. Notably, SPL did not affect spindle assembly in normal cells. Furthermore, the oral administration of SPL significantly suppressed tumor growth in vivo. The unique mechanism of action of SPL not only enables it to be used as a tool to dissect the molecular basis of spindle assembly but also to provide a rationale for the use of TACC3 as a molecular target for cancer treatment. This rationale offers an opportunity to develop new strategies for cancer chemotherapy that overcome the limitations of microtubule toxins and expand their scope and clinical efficacy.
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Affiliation(s)
- R Yao
- Department of Cell Biology, Cancer Institute, The Japanese Foundation for Cancer Research, Tokyo, Japan
| | - Y Kondoh
- Chemical Biology Core Facility, RIKEN Advanced Science Institute, Saitama, Japan
| | - Y Natsume
- Department of Cell Biology, Cancer Institute, The Japanese Foundation for Cancer Research, Tokyo, Japan
| | - H Yamanaka
- Department of Cell Biology, Cancer Institute, The Japanese Foundation for Cancer Research, Tokyo, Japan
| | - M Inoue
- 1] Department of Cell Biology, Cancer Institute, The Japanese Foundation for Cancer Research, Tokyo, Japan [2] Team for the Advanced Development and Evaluation of Human Disease Models, Bioresource Center, RIKEN, Tsukuba, Japan
| | - H Toki
- Team for the Advanced Development and Evaluation of Human Disease Models, Bioresource Center, RIKEN, Tsukuba, Japan
| | - R Takagi
- Chemical Biology Core Facility, RIKEN Advanced Science Institute, Saitama, Japan
| | - T Shimizu
- Chemical Biology Core Facility, RIKEN Advanced Science Institute, Saitama, Japan
| | - T Yamori
- Division of Molecular Pharmacology, Cancer Chemotherapy Center, The Japanese Foundation for Cancer Research, Tokyo, Japan
| | - H Osada
- Chemical Biology Core Facility, RIKEN Advanced Science Institute, Saitama, Japan
| | - T Noda
- 1] Department of Cell Biology, Cancer Institute, The Japanese Foundation for Cancer Research, Tokyo, Japan [2] Team for the Advanced Development and Evaluation of Human Disease Models, Bioresource Center, RIKEN, Tsukuba, Japan
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Adyshev DM, Dudek SM, Moldobaeva N, Kim KM, Ma SF, Kasa A, Garcia JGN, Verin AD. Ezrin/radixin/moesin proteins differentially regulate endothelial hyperpermeability after thrombin. Am J Physiol Lung Cell Mol Physiol 2013; 305:L240-55. [PMID: 23729486 DOI: 10.1152/ajplung.00355.2012] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Endothelial cell (EC) barrier disruption induced by inflammatory agonists such as thrombin leads to potentially lethal physiological dysfunction such as alveolar flooding, hypoxemia, and pulmonary edema. Thrombin stimulates paracellular gap and F-actin stress fiber formation, triggers actomyosin contraction, and alters EC permeability through multiple mechanisms that include protein kinase C (PKC) activation. We previously have shown that the ezrin, radixin, and moesin (ERM) actin-binding proteins differentially participate in sphingosine-1 phosphate-induced EC barrier enhancement. Phosphorylation of a conserved threonine residue in the COOH-terminus of ERM proteins causes conformational changes in ERM to unmask binding sites and is considered a hallmark of ERM activation. In the present study we test the hypothesis that ERM proteins are phosphorylated on this critical threonine residue by thrombin-induced signaling events and explore the role of the ERM family in modulating thrombin-induced cytoskeletal rearrangement and EC barrier function. Thrombin promotes ERM phosphorylation at this threonine residue (ezrin Thr567, radixin Thr564, moesin Thr558) in a PKC-dependent fashion and induces translocation of phosphorylated ERM to the EC periphery. Thrombin-induced ERM threonine phosphorylation is likely synergistically mediated by protease-activated receptors PAR1 and PAR2. Using the siRNA approach, depletion of either moesin alone or of all three ERM proteins significantly attenuates thrombin-induced increase in EC barrier permeability (transendothelial electrical resistance), cytoskeletal rearrangements, paracellular gap formation, and accumulation of phospho-myosin light chain. In contrast, radixin depletion exerts opposing effects on these indexes. These data suggest that ERM proteins play important differential roles in the thrombin-induced modulation of EC permeability, with moesin promoting barrier dysfunction and radixin opposing it.
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Affiliation(s)
- Djanybek M Adyshev
- Institute for Personalized Respiratory Medicine, Department of Medicine, Section of Pulmonary, Critical Care, Sleep, and Allergy, University of Illinois at Chicago, COMRB 3154, MC 719, 909 S. Wolcott Ave., Chicago, IL 60612, USA.
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Activated ERM protein plays a critical role in drug resistance of MOLT4 cells induced by CCL25. PLoS One 2013; 8:e52384. [PMID: 23326330 PMCID: PMC3541277 DOI: 10.1371/journal.pone.0052384] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 11/12/2012] [Indexed: 11/19/2022] Open
Abstract
We have previously demonstrated that the CCR9/CCL25 signaling pathway plays an important role in drug resistance in human acute T-lymphocytic leukemia (T-ALL) by inducing activation of ERM protein with polarized distribution in T-ALL cell line MOLT4. However, the mechanism of action of the activated ERM protein in the drug resistance of MOLT4 cells induced by CCL25 remains uncharacterized. Here we investigated the mechanism of CCR9/CCL25-initiated drug resistance in CCR9-high-expressing T-ALL cells. Our results showed that 1) the function of P-gp was increased after treatment with CCL25; 2) P-gp colocalized and co-immunoprecipitated with p-ERM and F-actin in CCL25 treated cells; and 3) ERM-shRNA conferred drug sensitivity coincident with release of ERM interactions with P-gp and F-actin after treatment with CCL25. These data suggest it is pivotal that P-gp associate with the F-actin cytoskeleton through p-ERM in CCR9/CCL25 induced multidrug resistance of T-ALL cells. Strategies aimed at inhibiting P-gp-F-actin cytoskeleton association may be helpful in increasing the efficiency of therapies in T-ALL.
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Hansen MDH, Kwiatkowski AV. Control of actin dynamics by allosteric regulation of actin binding proteins. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 303:1-25. [PMID: 23445807 DOI: 10.1016/b978-0-12-407697-6.00001-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The regulated assembly and organization of actin filaments allows the cell to construct a large diversity of actin-based structures specifically suited to a range of cellular processes. A vast array of actin regulatory proteins must work in concert to form specific actin networks within cells, and spatial and temporal requirements for actin assembly necessitate rapid regulation of protein activity. This chapter explores a common mechanism of controlling the activity of actin binding proteins: allosteric autoinhibition by interdomain head-tail interactions. Intramolecular interactions maintain these proteins in a closed conformation that masks protein domains needed to regulate actin dynamics. Autoinhibition is typically relieved by two or more ligand binding and/or posttranslational modification events that expose key protein domains. Regulation through multiple inputs permits precise temporal and spatial control of protein activity to guide actin network formation.
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Affiliation(s)
- Marc D H Hansen
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, UT, USA.
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41
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Giese AP, Ezan J, Wang L, Lasvaux L, Lembo F, Mazzocco C, Richard E, Reboul J, Borg JP, Kelley MW, Sans N, Brigande J, Montcouquiol M. Gipc1 has a dual role in Vangl2 trafficking and hair bundle integrity in the inner ear. Development 2012; 139:3775-85. [PMID: 22991442 DOI: 10.1242/dev.074229] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Vangl2 is one of the central proteins controlling the establishment of planar cell polarity in multiple tissues of different species. Previous studies suggest that the localization of the Vangl2 protein to specific intracellular microdomains is crucial for its function. However, the molecular mechanisms that control Vangl2 trafficking within a cell are largely unknown. Here, we identify Gipc1 (GAIP C-terminus interacting protein 1) as a new interactor for Vangl2, and we show that a myosin VI-Gipc1 protein complex can regulate Vangl2 traffic in heterologous cells. Furthermore, we show that in the cochlea of MyoVI mutant mice, Vangl2 presence at the membrane is increased, and that a disruption of Gipc1 function in hair cells leads to maturation defects, including defects in hair bundle orientation and integrity. Finally, stimulated emission depletion microscopy and overexpression of GFP-Vangl2 show an enrichment of Vangl2 on the supporting cell side, adjacent to the proximal membrane of hair cells. Altogether, these results indicate a broad role for Gipc1 in the development of both stereociliary bundles and cell polarization, and suggest that the strong asymmetry of Vangl2 observed in early postnatal cochlear epithelium is mostly a 'tissue' polarity readout.
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Affiliation(s)
- Arnaud P Giese
- Planar Polarity and Plasticity Group, Inserm U862, Neurocentre Magendie, Bordeaux, France
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Viswanatha R, Ohouo PY, Smolka MB, Bretscher A. Local phosphocycling mediated by LOK/SLK restricts ezrin function to the apical aspect of epithelial cells. ACTA ACUST UNITED AC 2012; 199:969-84. [PMID: 23209304 PMCID: PMC3518218 DOI: 10.1083/jcb.201207047] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Local cycling of LOK/SLK-dependent phosphorylation of ezrin is required for its apical localization and for microvillus formation. In this paper, we describe how a dynamic regulatory process is necessary to restrict microvilli to the apical aspect of polarized epithelial cells. We found that local phosphocycling regulation of ezrin, a critical plasma membrane–cytoskeletal linker of microvilli, was required to restrict its function to the apical membrane. Proteomic approaches and ribonucleic acid interference knockdown identified lymphocyte-oriented kinase (LOK) and SLK as the relevant kinases. Using drug-resistant LOK and SLK variants showed that these kinases were sufficient to restrict ezrin function to the apical domain. Both kinases were enriched in microvilli and locally activated there. Unregulated kinase activity caused ezrin mislocalization toward the basolateral domain, whereas expression of the kinase regulatory regions of LOK or SLK resulted in local inhibition of ezrin phosphorylation by the endogenous kinases. Thus, the domain-specific presence of microvilli is a dynamic process requiring a localized kinase driving the phosphocycling of ezrin to continually bias its function to the apical membrane.
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Affiliation(s)
- Raghuvir Viswanatha
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
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43
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Corcoran A, Cotter TG. FLT3-driven redox-modulation of Ezrin regulates leukaemic cell migration. Free Radic Res 2012; 47:20-34. [PMID: 23009217 DOI: 10.3109/10715762.2012.733385] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The concept of reactive oxygen species (ROS) being produced via the activation of specific oncogenes provides a basis for generating genomic instability and pro-survival signalling in tumour cells. The purpose of this study was to identify downstream targets of NADPH oxidase (Nox)-derived ROS signalling in acute myeloid leukaemia cells, by performing a proteomic analysis utilizing two-dimensional phosphotyrosine immunoblotting. The majority of the targets identified were cytoskeletal-associated proteins including Ezrin, a known regulator of the cytoskeleton, which was examined further. The study demonstrated that inhibition of Nox enzymes, using diphenyleneiodonium chloride in the acute myeloid leukaemia cell line MOLM-13, resulted in a decrease in Ezrin tyrosine phosphorylation and also triggered a shift in Ezrin sub-cellular localization as detected by immunofluorescence. The change in Ezrin localization coincided with altered cell morphology, observed using scanning electron microscopy and a decreased ability to migrate through a polycarbonate transwell membrane. Similar effects were observed upon inhibition of the oncogenic receptor tyrosine kinase FLT3 using the staurosporine derivate PKC412, implicating a role for FLT3 as an upstream regulator of Ezrin. Our results indicate that FLT3 drives production of ROS by Nox, which stimulates changes in Ezrin tyrosine phosphorylation and localization via redox regulation of Src. Furthermore, inhibition of FLT3 signalling leads to alterations in MOLM-13 cell morphology and has a significant influence on cell motility.
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Affiliation(s)
- Aoife Corcoran
- Tumour Biology Laboratory, Biochemistry Department, Biosciences Research Institute, University College Cork, Cork, Ireland
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Hieda M, Koizumi M, Higashi C, Tachibana T, Taguchi T, Higashiyama S. The cytoplasmic tail of heparin-binding EGF-like growth factor regulates bidirectional intracellular trafficking between the plasma membrane and ER. FEBS Open Bio 2012; 2:339-44. [PMID: 23650612 PMCID: PMC3642169 DOI: 10.1016/j.fob.2012.09.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Revised: 08/27/2012] [Accepted: 09/18/2012] [Indexed: 11/25/2022] Open
Abstract
Heparin-binding epidermal growth factor (EGF)- like growth factor (HB-EGF) is synthesized in the ER, transported along the exocytic pathway, and expressed on the plasma membrane as a type I transmembrane protein. Upon extracellular stimulation, HB-EGF, either proHB-EGF or the shed form HB-EGF-CTF, undergoes endocytosis and is then transported retrogradely to the ER. In this study, we showed the essential contribution of the short cytoplasmic tail of HB-EGF (HB-EGF-cyto) to the bidirectional intracellular trafficking between the ER and plasma membrane and revealed several critical amino acids residues that are responsible for internalization from the plasma membrane and ER targeting. We suggest that these anterograde and retrograde sorting signals within HB-EGF-cyto are strictly regulated by protein modification and conformation.
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Affiliation(s)
- Miki Hieda
- Department of Biochemistry and Molecular Genetics, Graduate School of Medicine, Ehime University, Ehime 791-0295, Japan
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Abstract
This review traces the historical origins and conceptual developments leading to the current state of knowledge of the three superfamilies of protein Ser/Thr phosphatases. 'PR enzyme' was identified as an enzyme that inactivates glycogen phosphorylase, although it took 10 years before this ugly duckling was recognized for its true identity as a protein Ser/Thr phosphatase. Ethanol denaturation for purification in the 1970s yielded a phosphatase that exhibited broad specificity, which was resolved into type-1 and type-2 phosphatases in the 1980s. More recent developments show that regulation and specificity are achieved through assembly of multisubunit holoenzymes, transient phosphorylation and the action of inhibitor proteins. Still not widely appreciated, there are hundreds of discrete protein Ser/Thr phosphatases available to counteract protein kinases, offering potential therapeutic targets. Signalling networks and modelling schemes need to incorporate the full gamut of protein Ser/Thr phosphatases and their interconnections.
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Affiliation(s)
- David L Brautigan
- Department of Microbiology, Immunology and Cancer Biology, Center for Cell Signaling, University of Virginia, School of Medicine, Charlottesville, VA 22908, USA.
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Shrestha S, Wilmeth LJ, Eyer J, Shuster CB. PRC1 controls spindle polarization and recruitment of cytokinetic factors during monopolar cytokinesis. Mol Biol Cell 2012; 23:1196-207. [PMID: 22323288 PMCID: PMC3315816 DOI: 10.1091/mbc.e11-12-1008] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PRC1 and KIF4A are believed to play a critical role in organizing antiparallel microtubules of the central spindle. Separable and nonredundant roles for these proteins were uncovered using cells with compromised spindle bipolarity, in which cytokinesis can be induced by bypassing the spindle assembly checkpoint. The central spindle is a postanaphase array of microtubules that plays an essential role in organizing the signaling machinery for cytokinesis. The model by which the central spindle organizes the cytokinetic apparatus is premised on an antiparallel arrangement of microtubules, yet cells lacking spindle bipolarity are capable of generating a distal domain of ectopic furrowing when forced into mitotic exit. Because protein regulator of cytokinesis (PRC1) and kinesin family member 4A (KIF4A) are believed to play a principal role in organizing the antiparallel midzone array, we sought to clarify their roles in monopolar cytokinesis. Although both factors localized to the distal ends of microtubules during monopolar cytokinesis, depletion of PRC1 and KIF4A displayed different phenotypes. Cells depleted of PRC1 failed to form a polarized microtubule array or ectopic furrows following mitotic exit, and recruitment of Aurora B kinase, male germ cell Rac GTPase-activating protein, and RhoA to the cortex was impaired. In contrast, KIF4A depletion impaired neither polarization nor ectopic furrowing, but it did result in elongated spindles with a diffuse distribution of cytokinetic factors. Thus, even in the absence of spindle bipolarity, PRC1 appears to be essential for polarizing parallel microtubules and concentrating the factors responsible for contractile ring assembly, whereas KIF4A is required for limiting the length of anaphase microtubules.
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Affiliation(s)
- Sanjay Shrestha
- Department of Biology, New Mexico State University, Las Cruces, NM 88003, USA
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47
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Yang Y, Primrose DA, Leung AC, Fitzsimmons RB, McDermand MC, Missellbrook A, Haskins J, Smylie AS, Hughes SC. The PP1 phosphatase flapwing regulates the activity of Merlin and Moesin in Drosophila. Dev Biol 2011; 361:412-26. [PMID: 22133918 DOI: 10.1016/j.ydbio.2011.11.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 11/09/2011] [Accepted: 11/10/2011] [Indexed: 01/21/2023]
Abstract
The signalling activities of Merlin and Moesin, two closely related members of the protein 4.1 Ezrin/Radixin/Moesin family, are regulated by conformational changes. These changes are regulated in turn by phosphorylation. The same sterile 20 kinase-Slik co-regulates Merlin or Moesin activity whereby phosphorylation inactivates Merlin, but activates Moesin. Thus, the corresponding coordinate activation of Merlin and inactivation of Moesin would require coordinated phosphatase activity. We find that Drosophila melanogaster protein phosphatase type 1 β (flapwing) fulfils this role, co-regulating dephosphorylation and altered activity of both Merlin and Moesin. Merlin or Moesin are detected in a complex with Flapwing both in-vitro and in-vivo. Directed changes in flapwing expression result in altered phosphorylation of both Merlin and Moesin. These changes in the levels of Merlin and Moesin phosphorylation following reduction of flapwing expression are associated with concomitant defects in epithelial integrity and increase in apoptosis in developing tissues such as wing imaginal discs. Functionally, the defects can be partially recapitulated by over expression of proteins that mimic constitutively phosphorylated or unphosphorylated Merlin or Moesin. Our results suggest that changes in the phosphorylation levels of Merlin and Moesin lead to changes in epithelial organization.
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Affiliation(s)
- Yang Yang
- Department of Cell Biology, University of Alberta, Edmonton, AB, Canada T6G 2H7
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48
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Antoine-Bertrand J, Ghogha A, Luangrath V, Bedford FK, Lamarche-Vane N. The activation of ezrin-radixin-moesin proteins is regulated by netrin-1 through Src kinase and RhoA/Rho kinase activities and mediates netrin-1-induced axon outgrowth. Mol Biol Cell 2011; 22:3734-46. [PMID: 21849478 PMCID: PMC3183026 DOI: 10.1091/mbc.e10-11-0917] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The receptor Deleted in Colorectal Cancer (DCC) mediates the attractive response of axons to the guidance cue netrin-1 during development. On netrin-1 stimulation, DCC is phosphorylated and induces the assembly of signaling complexes within the growth cone, leading to activation of cytoskeleton regulators, namely the GTPases Rac1 and Cdc42. The molecular mechanisms that link netrin-1/DCC to the actin machinery remain unclear. In this study we seek to demonstrate that the actin-binding proteins ezrin-radixin-moesin (ERM) are effectors of netrin-1/DCC signaling in embryonic cortical neurons. We show that ezrin associates with DCC in a netrin-1-dependent manner. We demonstrate that netrin-1/DCC induces ERM phosphorylation and activation and that the phosphorylation of DCC is required in that context. Moreover, Src kinases and RhoA/Rho kinase activities mediate netrin-1-induced ERM phosphorylation in neurons. We also observed that phosphorylated ERM proteins accumulate in growth cone filopodia, where they colocalize with DCC upon netrin-1 stimulation. Finally, we show that loss of ezrin expression in cortical neurons significantly decreases axon outgrowth induced by netrin-1. Together, our findings demonstrate that netrin-1 induces the formation of an activated ERM/DCC complex in growth cone filopodia, which is required for netrin-1-dependent cortical axon outgrowth.
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Takahashi S, Takei T, Koga H, Takatsu H, Shin HW, Nakayama K. Distinct roles of Rab11 and Arf6 in the regulation of Rab11-FIP3/arfophilin-1 localization in mitotic cells. Genes Cells 2011; 16:938-50. [PMID: 21790911 DOI: 10.1111/j.1365-2443.2011.01538.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Rab11 family interacting protein 3/arfophilin-1 is a dual effector of Rab11 and Arf6 and exhibits Rab11-dependent localization to recycling endosomes in interphase. Furthermore, FIP3 undergoes dynamic redistribution to the intercellular bridge during cytokinesis. However, regulation of FIP3 redistribution and its local function by Rab11 and Arf6 has remained controversial. In this study, we developed a procedure for detecting endogenous FIP3, Arf6, and Rab11 and determined that FIP3 is localized near the intercellular bridge during cytokinesis, and to the Flemming body (the midbody) immediately before abscission; Rab11 is localized near the intercellular bridge, but not to the Flemming body; and Arf6 is localized to the Flemming body. Time-lapse analyses showed that FIP3 is transported to the intercellular bridge during cytokinesis, together with Rab11; before abscission, FIP3 becomes localized to the Flemming body, where Arf6 is already present. After abscission, FIP3 and Arf6 are incorporated into one of the daughter cells as a Flemming body remnant. Based on these observations, we propose that FIP3 localization to recycling endosomes in interphase and their transport to the intercellular bridge during cytokinesis depend on Rab11, and targeting of FIP3-positive endosomal vesicles to the Flemming body in the abscission phase depends on Arf6.
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Affiliation(s)
- Senye Takahashi
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Japan
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50
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Ognibene M, Vanni C, Segalerba D, Mancini P, Merello E, Torrisi MR, Bosco MC, Varesio L, Eva A. The tumor suppressor hamartin enhances Dbl protein transforming activity through interaction with ezrin. J Biol Chem 2011; 286:29973-83. [PMID: 21712385 DOI: 10.1074/jbc.m111.270785] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The Rho guanine nucleotide exchange factor (GEF) Dbl binds to the N-terminal region of ezrin, a member of the ERM (ezrin, radixin, moesin) proteins known to function as linkers between the plasma membrane and the actin cytoskeleton. Here we have characterized the interaction between ezrin and Dbl. We show that binding of Dbl with ezrin involves positively charged amino acids within the region of the pleckstrin homology (PH) domain comprised between β1 and β2 sheets. In addition, we show that Dbl forms a complex with the tuberous sclerosis-1 (TSC-1) gene product hamartin and with ezrin. We demonstrate that hamartin and ezrin are both required for activation of Dbl. In fact, the knock-down of ezrin and hamartin, as well as the expression of a mutant hamartin, unable to bind ezrin, inhibit Dbl transforming and exchange activity. These results suggest that Dbl is regulated by hamartin through association with ezrin.
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Affiliation(s)
- Marzia Ognibene
- Laboratorio di Biologia Molecolare, Istituto G. Gaslini, Genova, Italy
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