1
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Locke TM, Fields R, Gizinski H, Otto GM, Shechner DM, Berg MD, Villen J, Sancak Y, Schweppe D. High-Throughput Identification of Calcium Regulated Proteins Across Diverse Proteomes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.18.575273. [PMID: 38293219 PMCID: PMC10827220 DOI: 10.1101/2024.01.18.575273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Calcium ions play important roles in nearly every biological process, yet whole-proteome analysis of calcium effectors has been hindered by lack of high-throughput, unbiased, and quantitative methods to identify proteins-calcium engagement. To address this, we adapted protein thermostability assays in the budding yeast, human cells, and mouse mitochondria. Based on calcium-dependent thermostability, we identified 2884 putative calcium-regulated proteins across human, mouse, and yeast proteomes. These data revealed calcium engagement of novel signaling hubs and cellular processes, including metabolic enzymes and the spliceosome. Cross-species comparison of calcium-protein engagement and mutagenesis experiments identified residue-specific cation engagement, even within well-known EF-hand domains. Additionally, we found that the dienoyl-CoA reductase DECR1 binds calcium at physiologically-relevant concentrations with substrate-specific affinity, suggesting direct calcium regulation of mitochondrial fatty acid oxidation. These unbiased, proteomic analyses of calcium effectors establish a key resource to dissect cation engagement and its mechanistic effects across multiple species and diverse biological processes.
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Affiliation(s)
- Timothy M Locke
- Department of Pharmacology, University of Washington, Seattle, Washington 98195, United States
| | - Rose Fields
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195, United States
| | - Hayden Gizinski
- Department of Pharmacology, University of Washington, Seattle, Washington 98195, United States
| | - George M Otto
- Department of Pharmacology, University of Washington, Seattle, Washington 98195, United States
| | - David M Shechner
- Department of Pharmacology, University of Washington, Seattle, Washington 98195, United States
| | - Matthew D Berg
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195, United States
| | - Judit Villen
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195, United States
| | - Yasemin Sancak
- Department of Pharmacology, University of Washington, Seattle, Washington 98195, United States
| | - Devin Schweppe
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195, United States
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2
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Vijayaraghavan T, Dhananjay S, Ho XY, Giordano-Santini R, Hilliard M, Neumann B. The dynamin GTPase mediates regenerative axonal fusion in Caenorhabditis elegans by regulating fusogen levels. PNAS NEXUS 2023; 2:pgad114. [PMID: 37181046 PMCID: PMC10167995 DOI: 10.1093/pnasnexus/pgad114] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 01/29/2023] [Accepted: 03/21/2023] [Indexed: 05/16/2023]
Abstract
Axonal fusion is a neuronal repair mechanism that results in the reconnection of severed axon fragments, leading to the restoration of cytoplasmic continuity and neuronal function. While synaptic vesicle recycling has been linked to axonal regeneration, its role in axonal fusion remains unknown. Dynamin proteins are large GTPases that hydrolyze lipid-binding membranes to carry out clathrin-mediated synaptic vesicle recycling. Here, we show that the Caenorhabditis elegans dynamin protein DYN-1 is a key component of the axonal fusion machinery. Animals carrying a temperature-sensitive allele of dyn-1(ky51) displayed wild-type levels of axonal fusion at the permissive temperature (15°C) but presented strongly reduced levels at the restrictive temperature (25°C). Furthermore, the average length of regrowth was significantly diminished in dyn-1(ky51) animals at the restrictive temperature. The expression of wild-type DYN-1 cell-autonomously into dyn-1(ky51) mutant animals rescued both the axonal fusion and regrowth defects. Furthermore, DYN-1 was not required prior to axonal injury, suggesting that it functions specifically after injury to control axonal fusion. Finally, using epistatic analyses and superresolution imaging, we demonstrate that DYN-1 regulates the levels of the fusogen protein EFF-1 post-injury to mediate axonal fusion. Together, these results establish DYN-1 as a novel regulator of axonal fusion.
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Affiliation(s)
- Tarika Vijayaraghavan
- Neuroscience Programme, Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, VIC 3800, Australia
| | - Samiksha Dhananjay
- Neuroscience Programme, Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, VIC 3800, Australia
| | - Xue Yan Ho
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Rosina Giordano-Santini
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Massimo Hilliard
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Brent Neumann
- Neuroscience Programme, Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, VIC 3800, Australia
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3
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Mishra R, Sengül GF, Candiello E, Schu P. Synaptic AP2 CCV life cycle regulation by the Eps15, ITSN1, Sgip1/AP2, synaptojanin1 interactome. Sci Rep 2021; 11:8007. [PMID: 33850201 PMCID: PMC8044098 DOI: 10.1038/s41598-021-87591-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 03/30/2021] [Indexed: 11/18/2022] Open
Abstract
The AP1/σ1B knockout causes impaired synaptic vesicle recycling and enhanced protein sorting into endosomes, leading to severe intellectual disability. These disturbances in synaptic protein sorting induce as a secondary phenotype the upregulation of AP2 CCV mediated endocytosis. Synapses contain canonical AP2 CCV and AP2 CCV with a more stable coat and thus extended life time. In AP1/σ1B knockout synapses, pool sizes of both CCV classes are doubled. Additionally, stable CCV of the knockout are more stabilised than stable wt CCV. One mechanism responsible for enhanced CCV stabilisation is the reduction of synaptojanin1 CCV levels, the PI-4,5-P2 phosphatase essential for AP2 membrane dissociation. To identify mechanisms regulating synaptojanin1 recruitment, we compared synaptojanin1 CCV protein interactome levels and CCV protein interactions between both CCV classes from wt and knockout mice. We show that ITSN1 determines synaptojanin1 CCV levels. Sgip1/AP2 excess hinders synaptojanin1 binding to ITSN1, further lowering its levels. ITSN1 levels are determined by Eps15, not Eps15L1. In addition, the data reveal that reduced amounts of pacsin1 can be counter balanced by its enhanced activation. These data exemplify the complexity of CCV life cycle regulation and indicate how cargo proteins determine the life cycle of their CCV.
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Affiliation(s)
- R Mishra
- Department of Cellular Biochemistry, University Medical Center, Georg-August University Göttingen, Humboldtallee 23, 37073, Göttingen, Germany
- Department of Clinical Neurosciences, John Van Geest Centre for Brain Repair, University of Cambridge, Cambridge, England, UK
| | - G F Sengül
- Department of Cellular Biochemistry, University Medical Center, Georg-August University Göttingen, Humboldtallee 23, 37073, Göttingen, Germany
| | - E Candiello
- Department of Cellular Biochemistry, University Medical Center, Georg-August University Göttingen, Humboldtallee 23, 37073, Göttingen, Germany
- Institute for Cancer Research and Treatment (IRCC), Turin, Italy
| | - P Schu
- Department of Cellular Biochemistry, University Medical Center, Georg-August University Göttingen, Humboldtallee 23, 37073, Göttingen, Germany.
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4
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Pimentel-Acosta CA, Ramírez-Salcedo J, Morales-Serna FN, Fajer-Ávila EJ, Chávez-Sánchez C, Lara HH, García-Gasca A. Molecular Effects of Silver Nanoparticles on Monogenean Parasites: Lessons from Caenorhabditis elegans. Int J Mol Sci 2020; 21:ijms21165889. [PMID: 32824343 PMCID: PMC7460582 DOI: 10.3390/ijms21165889] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 08/12/2020] [Accepted: 08/14/2020] [Indexed: 12/15/2022] Open
Abstract
The mechanisms of action of silver nanoparticles (AgNPs) in monogenean parasites of the genus Cichlidogyrus were investigated through a microarray hybridization approach using genomic information from the nematode Caenorhabditis elegans. The effects of two concentrations of AgNPs were explored, low (6 µg/L Ag) and high (36 µg/L Ag). Microarray analysis revealed that both concentrations of AgNPs activated similar biological processes, although by different mechanisms. Expression profiles included genes involved in detoxification, neurotoxicity, modulation of cell signaling, reproduction, embryonic development, and tegument organization as the main biological processes dysregulated by AgNPs. Two important processes (DNA damage and cell death) were mostly activated in parasites exposed to the lower concentration of AgNPs. To our knowledge, this is the first study providing information on the sub-cellular and molecular effects of exposure to AgNPs in metazoan parasites of fish.
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Affiliation(s)
- Citlalic A. Pimentel-Acosta
- Centro de Investigación en Alimentación y Desarrollo, Unidad Mazatlán en Acuicultura y Manejo Ambiental, Mazatlán, Sinaloa 82112, Mexico; (C.A.P.-A.); (F.N.M.-S.); (E.J.F.-Á.); (C.C.-S.)
| | - Jorge Ramírez-Salcedo
- Unidad de Microarreglos, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Mexico City 04510, Mexico;
| | - Francisco Neptalí Morales-Serna
- Centro de Investigación en Alimentación y Desarrollo, Unidad Mazatlán en Acuicultura y Manejo Ambiental, Mazatlán, Sinaloa 82112, Mexico; (C.A.P.-A.); (F.N.M.-S.); (E.J.F.-Á.); (C.C.-S.)
- CONACYT, Centro de Investigación en Alimentación y Desarrollo, Unidad Mazatlán en Acuicultura y Manejo Ambiental, Mazatlán, Sinaloa 82112, Mexico
| | - Emma J. Fajer-Ávila
- Centro de Investigación en Alimentación y Desarrollo, Unidad Mazatlán en Acuicultura y Manejo Ambiental, Mazatlán, Sinaloa 82112, Mexico; (C.A.P.-A.); (F.N.M.-S.); (E.J.F.-Á.); (C.C.-S.)
| | - Cristina Chávez-Sánchez
- Centro de Investigación en Alimentación y Desarrollo, Unidad Mazatlán en Acuicultura y Manejo Ambiental, Mazatlán, Sinaloa 82112, Mexico; (C.A.P.-A.); (F.N.M.-S.); (E.J.F.-Á.); (C.C.-S.)
| | - Humberto H. Lara
- Department of Biology and South Texas Center for Emerging Infectious Diseases, The University of Texas at San Antonio, San Antonio, TX 78249, USA;
| | - Alejandra García-Gasca
- Centro de Investigación en Alimentación y Desarrollo, Unidad Mazatlán en Acuicultura y Manejo Ambiental, Mazatlán, Sinaloa 82112, Mexico; (C.A.P.-A.); (F.N.M.-S.); (E.J.F.-Á.); (C.C.-S.)
- Correspondence: ; Tel.: +52-66-9989-8700
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5
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Endocytic Adaptor Proteins in Health and Disease: Lessons from Model Organisms and Human Mutations. Cells 2019; 8:cells8111345. [PMID: 31671891 PMCID: PMC6912373 DOI: 10.3390/cells8111345] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 10/24/2019] [Accepted: 10/25/2019] [Indexed: 12/11/2022] Open
Abstract
Cells need to exchange material and information with their environment. This is largely achieved via cell-surface receptors which mediate processes ranging from nutrient uptake to signaling responses. Consequently, their surface levels have to be dynamically controlled. Endocytosis constitutes a powerful mechanism to regulate the surface proteome and to recycle vesicular transmembrane proteins that strand at the plasma membrane after exocytosis. For efficient internalization, the cargo proteins need to be linked to the endocytic machinery via adaptor proteins such as the heterotetrameric endocytic adaptor complex AP-2 and a variety of mostly monomeric endocytic adaptors. In line with the importance of endocytosis for nutrient uptake, cell signaling and neurotransmission, animal models and human mutations have revealed that defects in these adaptors are associated with several diseases ranging from metabolic disorders to encephalopathies. This review will discuss the physiological functions of the so far known adaptor proteins and will provide a comprehensive overview of their links to human diseases.
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6
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Milesi C, Alberici P, Pozzi B, Oldani A, Beznoussenko GV, Raimondi A, Soppo BE, Amodio S, Caldieri G, Malabarba MG, Bertalot G, Confalonieri S, Parazzoli D, Mironov AA, Tacchetti C, Di Fiore PP, Sigismund S, Offenhäuser N. Redundant and nonredundant organismal functions of EPS15 and EPS15L1. Life Sci Alliance 2019; 2:2/1/e201800273. [PMID: 30692166 PMCID: PMC6350104 DOI: 10.26508/lsa.201800273] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 01/15/2019] [Accepted: 01/16/2019] [Indexed: 11/24/2022] Open
Abstract
This study unveils a redundant function for the endocytic proteins Eps15 and Eps15L1 in mouse embryo development and erythropoiesis, and a unique nonredundant role for Eps15L1 in the nervous system. EPS15 and its homologous EPS15L1 are endocytic accessory proteins. Studies in mammalian cell lines suggested that EPS15 and EPS15L1 regulate endocytosis in a redundant manner. However, at the organismal level, it is not known to which extent the functions of the two proteins overlap. Here, by exploiting various constitutive and conditional null mice, we report redundant and nonredundant functions of the two proteins. EPS15L1 displays a unique nonredundant role in the nervous system, whereas both proteins are fundamental during embryo development as shown by the embryonic lethality of -Eps15/Eps15L1-double KO mice. At the cellular level, the major process redundantly regulated by EPS15 and EPS15L1 is the endocytosis of the transferrin receptor, a pathway that sustains the development of red blood cells and controls iron homeostasis. Consequently, hematopoietic-specific conditional Eps15/Eps15L1-double KO mice display traits of microcytic hypochromic anemia, due to a cell-autonomous defect in iron internalization.
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Affiliation(s)
- Cinzia Milesi
- IFOM, Fondazione Istituto FIRC (Fondazione Italiana per la Ricerca sul Cancro) di Oncologia Molecolare, Milan, Italy
| | - Paola Alberici
- IFOM, Fondazione Istituto FIRC (Fondazione Italiana per la Ricerca sul Cancro) di Oncologia Molecolare, Milan, Italy
| | - Benedetta Pozzi
- IFOM, Fondazione Istituto FIRC (Fondazione Italiana per la Ricerca sul Cancro) di Oncologia Molecolare, Milan, Italy
| | - Amanda Oldani
- IFOM, Fondazione Istituto FIRC (Fondazione Italiana per la Ricerca sul Cancro) di Oncologia Molecolare, Milan, Italy.,Cogentech Società Benefit Srl, Milan, Italy
| | - Galina V Beznoussenko
- IFOM, Fondazione Istituto FIRC (Fondazione Italiana per la Ricerca sul Cancro) di Oncologia Molecolare, Milan, Italy
| | - Andrea Raimondi
- Experimental Imaging Centre, Istituto di Ricovero e Cura a Carattere Scientifico, San Raffaele Scientific Institute, Milan, Italy
| | - Blanche Ekalle Soppo
- IFOM, Fondazione Istituto FIRC (Fondazione Italiana per la Ricerca sul Cancro) di Oncologia Molecolare, Milan, Italy.,IEO, Istituto Europeo di Oncologia IRCCS (Istituti di Ricovero e Cura a Carattere Scientifico), Milan, Italy
| | - Stefania Amodio
- IFOM, Fondazione Istituto FIRC (Fondazione Italiana per la Ricerca sul Cancro) di Oncologia Molecolare, Milan, Italy.,IEO, Istituto Europeo di Oncologia IRCCS (Istituti di Ricovero e Cura a Carattere Scientifico), Milan, Italy
| | - Giusi Caldieri
- IFOM, Fondazione Istituto FIRC (Fondazione Italiana per la Ricerca sul Cancro) di Oncologia Molecolare, Milan, Italy.,IEO, Istituto Europeo di Oncologia IRCCS (Istituti di Ricovero e Cura a Carattere Scientifico), Milan, Italy.,Università degli Studi di Milano, Dipartimento di Oncologia ed Emato-oncologia, Milan, Italy
| | - Maria Grazia Malabarba
- IFOM, Fondazione Istituto FIRC (Fondazione Italiana per la Ricerca sul Cancro) di Oncologia Molecolare, Milan, Italy.,IEO, Istituto Europeo di Oncologia IRCCS (Istituti di Ricovero e Cura a Carattere Scientifico), Milan, Italy.,Università degli Studi di Milano, Dipartimento di Oncologia ed Emato-oncologia, Milan, Italy
| | - Giovanni Bertalot
- IEO, Istituto Europeo di Oncologia IRCCS (Istituti di Ricovero e Cura a Carattere Scientifico), Milan, Italy
| | - Stefano Confalonieri
- IFOM, Fondazione Istituto FIRC (Fondazione Italiana per la Ricerca sul Cancro) di Oncologia Molecolare, Milan, Italy.,IEO, Istituto Europeo di Oncologia IRCCS (Istituti di Ricovero e Cura a Carattere Scientifico), Milan, Italy
| | - Dario Parazzoli
- IFOM, Fondazione Istituto FIRC (Fondazione Italiana per la Ricerca sul Cancro) di Oncologia Molecolare, Milan, Italy.,Cogentech Società Benefit Srl, Milan, Italy
| | - Alexander A Mironov
- IFOM, Fondazione Istituto FIRC (Fondazione Italiana per la Ricerca sul Cancro) di Oncologia Molecolare, Milan, Italy
| | - Carlo Tacchetti
- Experimental Imaging Centre, Istituto di Ricovero e Cura a Carattere Scientifico, San Raffaele Scientific Institute, Milan, Italy.,Dipartimento di Medicina Sperimentale, Università degli Studi di Genova, Genoa, Italy
| | - Pier Paolo Di Fiore
- IFOM, Fondazione Istituto FIRC (Fondazione Italiana per la Ricerca sul Cancro) di Oncologia Molecolare, Milan, Italy.,IEO, Istituto Europeo di Oncologia IRCCS (Istituti di Ricovero e Cura a Carattere Scientifico), Milan, Italy.,Università degli Studi di Milano, Dipartimento di Oncologia ed Emato-oncologia, Milan, Italy
| | - Sara Sigismund
- IFOM, Fondazione Istituto FIRC (Fondazione Italiana per la Ricerca sul Cancro) di Oncologia Molecolare, Milan, Italy .,IEO, Istituto Europeo di Oncologia IRCCS (Istituti di Ricovero e Cura a Carattere Scientifico), Milan, Italy.,Università degli Studi di Milano, Dipartimento di Oncologia ed Emato-oncologia, Milan, Italy
| | - Nina Offenhäuser
- IFOM, Fondazione Istituto FIRC (Fondazione Italiana per la Ricerca sul Cancro) di Oncologia Molecolare, Milan, Italy .,Cogentech Società Benefit Srl, Milan, Italy
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7
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Gan Q, Watanabe S. Synaptic Vesicle Endocytosis in Different Model Systems. Front Cell Neurosci 2018; 12:171. [PMID: 30002619 PMCID: PMC6031744 DOI: 10.3389/fncel.2018.00171] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Accepted: 06/01/2018] [Indexed: 11/13/2022] Open
Abstract
Neurotransmission in complex animals depends on a choir of functionally distinct synapses releasing neurotransmitters in a highly coordinated manner. During synaptic signaling, vesicles fuse with the plasma membrane to release their contents. The rate of vesicle fusion is high and can exceed the rate at which synaptic vesicles can be re-supplied by distant sources. Thus, local compensatory endocytosis is needed to replenish the synaptic vesicle pools. Over the last four decades, various experimental methods and model systems have been used to study the cellular and molecular mechanisms underlying synaptic vesicle cycle. Clathrin-mediated endocytosis is thought to be the predominant mechanism for synaptic vesicle recycling. However, recent studies suggest significant contribution from other modes of endocytosis, including fast compensatory endocytosis, activity-dependent bulk endocytosis, ultrafast endocytosis, as well as kiss-and-run. Currently, it is not clear whether a universal model of vesicle recycling exist for all types of synapses. It is possible that each synapse type employs a particular mode of endocytosis. Alternatively, multiple modes of endocytosis operate at the same synapse, and the synapse toggles between different modes depending on its activity level. Here we compile review and research articles based on well-characterized model systems: frog neuromuscular junctions, C. elegans neuromuscular junctions, Drosophila neuromuscular junctions, lamprey reticulospinal giant axons, goldfish retinal ribbon synapses, the calyx of Held, and rodent hippocampal synapses. We will compare these systems in terms of their known modes and kinetics of synaptic vesicle endocytosis, as well as the underlying molecular machineries. We will also provide the future development of this field.
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Affiliation(s)
- Quan Gan
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Shigeki Watanabe
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, United States.,Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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8
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Wang L, Johnson A, Hanna M, Audhya A. Eps15 membrane-binding and -bending activity acts redundantly with Fcho1 during clathrin-mediated endocytosis. Mol Biol Cell 2016; 27:2675-87. [PMID: 27385343 PMCID: PMC5007088 DOI: 10.1091/mbc.e16-03-0151] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 06/29/2016] [Indexed: 11/11/2022] Open
Abstract
Clathrin-mediated endocytosis involves a network of proteins that direct cargo capture while simultaneously facilitating membrane remodeling. Eps15 is a critical factor that binds and bends membranes and acts redundantly with Fcho1 to ensure clathrin lattice stability during the initial stages of plasma membrane invagination. Clathrin coat assembly on membranes requires cytosolic adaptors and accessory proteins, which bridge triskeleons with the lipid bilayer and stabilize lattice architecture throughout the process of vesicle formation. In Caenorhabditis elegans, the prototypical AP-2 adaptor complex, which is activated by the accessory factor Fcho1 at the plasma membrane, is dispensable during embryogenesis, enabling us to define alternative mechanisms that facilitate clathrin-mediated endocytosis. Here we uncover a synthetic genetic interaction between C. elegans Fcho1 (FCHO-1) and Eps15 (EHS-1), suggesting that they function in a parallel and potentially redundant manner. Consistent with this idea, we find that the FCHO-1 EFC/F-BAR domain and the EHS-1 EH domains exhibit highly similar membrane-binding and -bending characteristics in vitro. Furthermore, we demonstrate a critical role for EHS-1 when FCHO-1 membrane-binding and -bending activity is specifically eliminated in vivo. Taken together, our data highlight Eps15 as an important membrane-remodeling factor, which acts in a partially redundant manner with Fcho proteins during the earliest stages of clathrin-mediated endocytosis.
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Affiliation(s)
- Lei Wang
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53706
| | - Adam Johnson
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53706
| | - Michael Hanna
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53706
| | - Anjon Audhya
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53706
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9
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Hwang J, Pallas DC. STRIPAK complexes: structure, biological function, and involvement in human diseases. Int J Biochem Cell Biol 2014; 47:118-48. [PMID: 24333164 PMCID: PMC3927685 DOI: 10.1016/j.biocel.2013.11.021] [Citation(s) in RCA: 170] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2013] [Revised: 11/18/2013] [Accepted: 11/28/2013] [Indexed: 12/31/2022]
Abstract
The mammalian striatin family consists of three proteins, striatin, S/G2 nuclear autoantigen, and zinedin. Striatin family members have no intrinsic catalytic activity, but rather function as scaffolding proteins. Remarkably, they organize multiple diverse, large signaling complexes that participate in a variety of cellular processes. Moreover, they appear to be regulatory/targeting subunits for the major eukaryotic serine/threonine protein phosphatase 2A. In addition, striatin family members associate with germinal center kinase III kinases as well as other novel components, earning these assemblies the name striatin-interacting phosphatase and kinase (STRIPAK) complexes. Recently, there has been a great increase in functional and mechanistic studies aimed at identifying and understanding the roles of STRIPAK and STRIPAK-like complexes in cellular processes of multiple organisms. These studies have identified novel STRIPAK and STRIPAK-like complexes and have explored their roles in specific signaling pathways. Together, the results of these studies have sparked increased interest in striatin family complexes because they have revealed roles in signaling, cell cycle control, apoptosis, vesicular trafficking, Golgi assembly, cell polarity, cell migration, neural and vascular development, and cardiac function. Moreover, STRIPAK complexes have been connected to clinical conditions, including cardiac disease, diabetes, autism, and cerebral cavernous malformation. In this review, we discuss the expression, localization, and protein domain structure of striatin family members. Then we consider the diverse complexes these proteins and their homologs form in various organisms, emphasizing what is known regarding function and regulation. Finally, we explore possible roles of striatin family complexes in disease, especially cerebral cavernous malformation.
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Affiliation(s)
- Juyeon Hwang
- Department of Biochemistry and Winship Cancer Institute, and Biochemistry, Cell, Developmental Biology Graduate Program, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA 30322, USA.
| | - David C Pallas
- Department of Biochemistry and Winship Cancer Institute, and Biochemistry, Cell, Developmental Biology Graduate Program, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA 30322, USA.
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10
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Tsushima H, Malabarba MG, Confalonieri S, Senic-Matuglia F, Verhoef LGGC, Bartocci C, D'Ario G, Cocito A, Di Fiore PP, Salcini AE. A snapshot of the physical and functional wiring of the Eps15 homology domain network in the nematode. PLoS One 2013; 8:e56383. [PMID: 23424658 PMCID: PMC3570524 DOI: 10.1371/journal.pone.0056383] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 01/13/2013] [Indexed: 12/12/2022] Open
Abstract
Protein interaction modules coordinate the connections within and the activity of intracellular signaling networks. The Eps15 Homology (EH) module, a protein-protein interaction domain that is a key feature of the EH-network, was originally identified in a few proteins involved in endocytosis and vesicle trafficking, and has subsequently also been implicated in actin reorganization, nuclear shuttling, and DNA repair. Here we report an extensive characterization of the physical connections and of the functional wirings of the EH-network in the nematode. Our data show that one of the major physiological roles of the EH-network is in neurotransmission. In addition, we found that the proteins of the network intersect, and possibly coordinate, a number of “territories” of cellular activity including endocytosis/recycling/vesicle transport, actin dynamics, general metabolism and signal transduction, ubiquitination/degradation of proteins, DNA replication/repair, and miRNA biogenesis and processing.
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Affiliation(s)
- Hanako Tsushima
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Milan, Italy
| | - Maria Grazia Malabarba
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Milan, Italy
- Dipartimento di Medicina, Chirurgia ed Odontoiatria, Università degli Studi di Milano, Milan, Italy
| | | | | | | | - Cristina Bartocci
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Milan, Italy
| | - Giovanni D'Ario
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Milan, Italy
| | - Andrea Cocito
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Milan, Italy
| | - Pier Paolo Di Fiore
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Milan, Italy
- Dipartimento di Medicina, Chirurgia ed Odontoiatria, Università degli Studi di Milano, Milan, Italy
- Istituto Europeo di Oncologia, Milan, Italy
- * E-mail: (PPDF); (AES)
| | - Anna Elisabetta Salcini
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Milan, Italy
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark
- * E-mail: (PPDF); (AES)
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11
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Hanna M, Wang L, Audhya A. Worming our way in and out of the Caenorhabditis elegans germline and developing embryo. Traffic 2013; 14:471-8. [PMID: 23331906 DOI: 10.1111/tra.12044] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 01/11/2013] [Accepted: 01/17/2013] [Indexed: 12/18/2022]
Abstract
The germline and embryo of the nematode Caenorhabditis elegans have emerged as powerful model systems to study membrane dynamics in an intact, developing animal. In large part, this is due to the architecture of the reproductive system, which necessitates de novo membrane and organelle biogenesis within the stem cell niche to drive compartmentalization throughout the gonad syncytium. Additionally, membrane reorganization events during oocyte maturation and fertilization have been demonstrated to be highly stereotypic, facilitating the development of quantitative assays to measure the impact of perturbations on protein transport. This review will focus on regulatory mechanisms that govern protein trafficking, which have been elucidated using a combination of C. elegans genetics, biochemistry and high-resolution microscopy. Collectively, studies using the simple worm highlight an important niche that the organism holds to define new pathways that regulate vesicle transport, many of which appear to be absent in unicellular systems but remain highly conserved in mammals.
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Affiliation(s)
- Michael Hanna
- Department of Biomolecular Chemistry, University of Wisconsin-Madison Medical School, 440 Henry Mall, Madison, WI 53706, USA
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12
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Gubar O, Morderer D, Tsyba L, Croisé P, Houy S, Ory S, Gasman S, Rynditch A. Intersectin: The Crossroad between Vesicle Exocytosis and Endocytosis. Front Endocrinol (Lausanne) 2013; 4:109. [PMID: 23986746 PMCID: PMC3753573 DOI: 10.3389/fendo.2013.00109] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 08/09/2013] [Indexed: 12/24/2022] Open
Abstract
Intersectins (ITSNs) are a family of highly conserved proteins with orthologs from nematodes to mammals. In vertebrates, ITSNs are encoded by two genes (itsn1 and itsn2), which act as scaffolds that were initially discovered as proteins involved in endocytosis. Further investigation demonstrated that ITSN1 is also implicated in several other processes including regulated exocytosis, thereby suggesting a role for ITSN1 in the coupling between exocytosis and endocytosis in excitatory cells. Despite a high degree of conservation amongst orthologs, ITSN function is not so well preserved as they have acquired new properties during evolution. In this review, we will discuss the role of ITSN1 and its orthologs in exo- and endocytosis, in particular in neurons and neuroendocrine cells.
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Affiliation(s)
- Olga Gubar
- State Key Laboratory of Molecular and Cellular Biology, Institute of Molecular Biology and Genetics, Kyiv, Ukraine
- Department of Functional Genomics, Institute of Molecular Biology and Genetics, Kyiv, Ukraine
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique-Unité Propre de Recherche 3212, Université de Strasbourg, Strasbourg, France
| | - Dmytro Morderer
- State Key Laboratory of Molecular and Cellular Biology, Institute of Molecular Biology and Genetics, Kyiv, Ukraine
- Department of Functional Genomics, Institute of Molecular Biology and Genetics, Kyiv, Ukraine
| | - Lyudmila Tsyba
- Department of Functional Genomics, Institute of Molecular Biology and Genetics, Kyiv, Ukraine
| | - Pauline Croisé
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique-Unité Propre de Recherche 3212, Université de Strasbourg, Strasbourg, France
| | - Sébastien Houy
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique-Unité Propre de Recherche 3212, Université de Strasbourg, Strasbourg, France
| | - Stéphane Ory
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique-Unité Propre de Recherche 3212, Université de Strasbourg, Strasbourg, France
| | - Stéphane Gasman
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique-Unité Propre de Recherche 3212, Université de Strasbourg, Strasbourg, France
| | - Alla Rynditch
- State Key Laboratory of Molecular and Cellular Biology, Institute of Molecular Biology and Genetics, Kyiv, Ukraine
- Department of Functional Genomics, Institute of Molecular Biology and Genetics, Kyiv, Ukraine
- *Correspondence: Alla Rynditch, Department of Functional Genomics, Institute of Molecular Biology and Genetics, 150, Zabolotnogo Street, 03680 Kyiv-143, Ukraine e-mail:
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13
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The endocytic adaptor Eps15 controls marginal zone B cell numbers. PLoS One 2012; 7:e50818. [PMID: 23226392 PMCID: PMC3511280 DOI: 10.1371/journal.pone.0050818] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Accepted: 10/29/2012] [Indexed: 11/19/2022] Open
Abstract
Eps15 is an endocytic adaptor protein involved in clathrin and non-clathrin mediated endocytosis. In Caenorhabditis elegans and Drosophila melanogaster lack of Eps15 leads to defects in synaptic vesicle recycling and synapse formation. We generated Eps15-KO mice to investigate its function in mammals. Eps15-KO mice are born at the expected Mendelian ratio and are fertile. Using a large-scale phenotype screen covering more than 300 parameters correlated to human disease, we found that Eps15-KO mice did not show any sign of disease or neural deficits. Instead, altered blood parameters pointed to an immunological defect. By competitive bone marrow transplantation we demonstrated that Eps15-KO hematopoietic precursor cells were more efficient than the WT counterparts in repopulating B220⁺ bone marrow cells, CD19⁻ thymocytes and splenic marginal zone (MZ) B cells. Eps15-KO mice showed a 2-fold increase in MZ B cell numbers when compared with controls. Using reverse bone marrow transplantation, we found that Eps15 regulates MZ B cell numbers in a cell autonomous manner. FACS analysis showed that although MZ B cells were increased in Eps15-KO mice, transitional and pre-MZ B cell numbers were unaffected. The increase in MZ B cell numbers in Eps15 KO mice was not dependent on altered BCR signaling or Notch activity. In conclusion, in mammals, the endocytic adaptor protein Eps15 is a regulator of B-cell lymphopoiesis.
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14
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Abstract
Neurons can sustain high rates of synaptic transmission without exhausting their supply of synaptic vesicles. This property relies on a highly efficient local endocytic recycling of synaptic vesicle membranes, which can be reused for hundreds, possibly thousands, of exo-endocytic cycles. Morphological, physiological, molecular, and genetic studies over the last four decades have provided insight into the membrane traffic reactions that govern this recycling and its regulation. These studies have shown that synaptic vesicle endocytosis capitalizes on fundamental and general endocytic mechanisms but also involves neuron-specific adaptations of such mechanisms. Thus, investigations of these processes have advanced not only the field of synaptic transmission but also, more generally, the field of endocytosis. This article summarizes current information on synaptic vesicle endocytosis with an emphasis on the underlying molecular mechanisms and with a special focus on clathrin-mediated endocytosis, the predominant pathway of synaptic vesicle protein internalization.
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Affiliation(s)
- Yasunori Saheki
- Department of Cell Biology, Howard Hughes Medical Institute and Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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15
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Kumar M, Ahmad S, Ahmad E, Saifi MA, Khan RH. In silico prediction and analysis of Caenorhabditis EF-hand containing proteins. PLoS One 2012; 7:e36770. [PMID: 22701514 PMCID: PMC3360750 DOI: 10.1371/journal.pone.0036770] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Accepted: 04/12/2012] [Indexed: 01/12/2023] Open
Abstract
Calcium (Ca⁺²) is a ubiquitous messenger in eukaryotes including Caenorhabditis. Ca⁺²-mediated signalling processes are usually carried out through well characterized proteins like calmodulin (CaM) and other Ca⁺² binding proteins (CaBP). These proteins interact with different targets and activate it by bringing conformational changes. Majority of the EF-hand proteins in Caenorhabditis contain Ca⁺² binding motifs. Here, we have performed homology modelling of CaM-like proteins using the crystal structure of Drosophila melanogaster CaM as a template. Molecular docking was applied to explore the binding mechanism of CaM-like proteins and IQ1 motif which is a ∼25 residues and conform to the consensus sequence (I, L, V)QXXXRXXXX(R,K) to serve as a binding site for different EF hand proteins. We made an attempt to identify all the EF-hand (a helix-loop-helix structure characterized by a 12 residues loop sequence involved in metal coordination) containing proteins and their Ca⁺² binding affinity in Caenorhabditis by analysing the complete genome sequence. Docking studies revealed that F165, F169, L29, E33, F44, L57, M61, M96, M97, M108, G65, V115, F93, N104, E144 of CaM-like protein is involved in the interaction with IQ1 motif. A maximum of 170 EF-hand proteins and 39 non-EF-hand proteins with Ca⁺²/metal binding motif were identified. Diverse proteins including enzyme, transcription, translation and large number of unknown proteins have one or more putative EF-hands. Phylogenetic analysis revealed seven major classes/groups that contain some families of proteins. Various domains that we identified in the EF-hand proteins (uncharacterized) would help in elucidating their functions. It is the first report of its kind where calcium binding loop sequences of EF-hand proteins were analyzed to decipher their calcium affinities. Variation in Ca⁺²-binding affinity of EF-hand CaBP could be further used to study the behaviour of these proteins. Our analyses postulated that Ca⁺² is likely to be key player in Caenorhabditis cell signalling.
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Affiliation(s)
- Manish Kumar
- Advanced Instrumentation Research Facility, Jawaharlal Nehru University, New Delhi, India
| | - Shadab Ahmad
- Centre for Computational Biology and Bioinformatics, Jawaharlal Nehru University, New Delhi, India
| | - Ejaz Ahmad
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India
| | - Muheet Alam Saifi
- Department of Zoology, College of Science, King Saud University, Riyadh, Kingdom of Saudi Arabia
| | - Rizwan Hasan Khan
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India
- * E-mail:
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16
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Abstract
We review mainly the work from our research group here. Our focus has been on the use of genetic methods to delineate the mechanisms of synaptic vesicle recycling and cellular trafficking. Acute temperature-sensitive paralytic mutants have been of particular value in this approach. We have primarily used screens for suppressor and enhancer mutations to identify genetic loci coding for proteins that interact with Dynamin in Drosophila. In addition, we have used reverse genetic approaches to investigate few other candidate molecules that may play a role in synaptic vesicle endocytosis. We have in particular discussed at some length the role of endocytic accessory proteins Stoned and Eps15 in vesicle recycling.
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Affiliation(s)
- Riddhi Majumder
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
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17
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The phocein homologue SmMOB3 is essential for vegetative cell fusion and sexual development in the filamentous ascomycete Sordaria macrospora. Curr Genet 2011; 57:133-49. [PMID: 21229248 PMCID: PMC3059760 DOI: 10.1007/s00294-010-0333-z] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Revised: 12/06/2010] [Accepted: 12/27/2010] [Indexed: 01/11/2023]
Abstract
Members of the striatin family and their highly conserved interacting protein phocein/Mob3 are key components in the regulation of cell differentiation in multicellular eukaryotes. The striatin homologue PRO11 of the filamentous ascomycete Sordaria macrospora has a crucial role in fruiting body development. Here, we functionally characterized the phocein/Mob3 orthologue SmMOB3 of S. macrospora. We isolated the gene and showed that both, pro11 and Smmob3 are expressed during early and late developmental stages. Deletion of Smmob3 resulted in a sexually sterile strain, similar to the previously characterized pro11 mutant. Fusion assays revealed that ∆Smmob3 was unable to undergo self-fusion and fusion with the pro11 strain. The essential function of the SmMOB3 N-terminus containing the conserved mob domain was demonstrated by complementation analysis of the sterile S. macrospora ∆Smmob3 strain. Downregulation of either pro11 in ∆Smmob3, or Smmob3 in pro11 mutants by means of RNA interference (RNAi) resulted in synthetic sexual defects, demonstrating for the first time the importance of a putative PRO11/SmMOB3 complex in fruiting body development.
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18
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Pece S, Confalonieri S, R Romano P, Di Fiore PP. NUMB-ing down cancer by more than just a NOTCH. BIOCHIMICA ET BIOPHYSICA ACTA 2011; 1815:26-43. [PMID: 20940030 DOI: 10.1016/j.bbcan.2010.10.001] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Revised: 09/30/2010] [Accepted: 10/02/2010] [Indexed: 02/07/2023]
Abstract
The protein Numb does not live up to its name. This passive-sounding protein is anything but spent. Originally identified as a cell-fate determinant in Drosophila development, Numb received a good deal of attention as an inhibitor of the Notch receptor signaling pathway. It turns out, however, that Numb does a lot more than simply regulate Notch. It has been implicated in a variety of biochemical pathways connected with signaling (it regulates Notch-, Hedgehog- and TP53-activated pathways), endocytosis (it is involved in cargo internalization and recycling), determination of polarity (it interacts with the PAR complex, and regulates adherens and tight junctions), and ubiquitination (it exploits this mechanism to regulate protein function and stability). This complex biochemical network lies at the heart of Numb's involvement in diverse cellular phenotypes, including cell fate developmental decisions, maintenance of stem cell compartments, regulation of cell polarity and adhesion, and migration. Considering its multifaceted role in cellular homeostasis, it is not surprising that Numb has been implicated in cancer as a tumor suppressor. Our major goal here is to explain the cancer-related role of Numb based on our understanding of its role in cell physiology. We will attempt to do this by reviewing the present knowledge of Numb at the biochemical and functional level, and by integrating its apparently heterogeneous functions into a unifying scenario, based on our recently proposed concept of the "endocytic matrix". Finally, we will discuss the role of Numb in the maintenance of the normal stem cell compartment, as a starting point to interpret the tumor suppressor function of Numb in the context of the cancer stem cell hypothesis.
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Affiliation(s)
- Salvatore Pece
- Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139, Milan, Italy
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19
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Conserved genes act as modifiers of invertebrate SMN loss of function defects. PLoS Genet 2010; 6:e1001172. [PMID: 21124729 PMCID: PMC2965752 DOI: 10.1371/journal.pgen.1001172] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Accepted: 09/21/2010] [Indexed: 01/27/2023] Open
Abstract
Spinal Muscular Atrophy (SMA) is caused by diminished function of the Survival of Motor Neuron (SMN) protein, but the molecular pathways critical for SMA pathology remain elusive. We have used genetic approaches in invertebrate models to identify conserved SMN loss of function modifier genes. Drosophila melanogaster and Caenorhabditis elegans each have a single gene encoding a protein orthologous to human SMN; diminished function of these invertebrate genes causes lethality and neuromuscular defects. To find genes that modulate SMN function defects across species, two approaches were used. First, a genome-wide RNAi screen for C. elegans SMN modifier genes was undertaken, yielding four genes. Second, we tested the conservation of modifier gene function across species; genes identified in one invertebrate model were tested for function in the other invertebrate model. Drosophila orthologs of two genes, which were identified originally in C. elegans, modified Drosophila SMN loss of function defects. C. elegans orthologs of twelve genes, which were originally identified in a previous Drosophila screen, modified C. elegans SMN loss of function defects. Bioinformatic analysis of the conserved, cross-species, modifier genes suggests that conserved cellular pathways, specifically endocytosis and mRNA regulation, act as critical genetic modifiers of SMN loss of function defects across species.
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20
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Affiliation(s)
- Jeremy Dittman
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065; ,
| | - Timothy A. Ryan
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065; ,
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21
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Differential requirements for clathrin in receptor-mediated endocytosis and maintenance of synaptic vesicle pools. Proc Natl Acad Sci U S A 2009; 106:1139-44. [PMID: 19151157 DOI: 10.1073/pnas.0809541106] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Clathrin is a coat protein involved in vesicle budding from several membrane-bound compartments within the cell. Here we present an analysis of a temperature-sensitive (ts) mutant of clathrin heavy chain (CHC) in a multicellular animal. As expected Caenorhabditis elegans chc-1(b1025ts) mutant animals are defective in receptor-mediated endocytosis and arrest development soon after being shifted to the restrictive temperature. Steady-state clathrin levels in these mutants are reduced by more than 95% at all temperatures. Hub interactions and membrane associations are lost at the restrictive temperature. chc-1(b1025ts) animals become paralyzed within minutes of exposure to the restrictive temperature because of a defect in the nervous system. Surprisingly synaptic vesicle number is not reduced in chc-1(b1025ts) animals. Consistent with the normal number of vesicles, postsynaptic miniature currents occur at normal frequencies. Taken together, these results indicate that a high level of CHC activity is required for receptor-mediated endocytosis in nonneuronal cells but is largely dispensable for maintenance of synaptic vesicle pools.
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22
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Perez-Mansilla B, Nurrish S. A network of G-protein signaling pathways control neuronal activity in C. elegans. ADVANCES IN GENETICS 2009; 65:145-192. [PMID: 19615533 DOI: 10.1016/s0065-2660(09)65004-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The Caenorhabditis elegans neuromuscular junction (NMJ) is one of the best studied synapses in any organism. A variety of genetic screens have identified genes required both for the essential steps of neurotransmitter release from motorneurons as well as the signaling pathways that regulate rates of neurotransmitter release. A number of these regulatory genes encode proteins that converge to regulate neurotransmitter release. In other cases genes are known to regulate signaling at the NMJ but how they act remains unknown. Many of the proteins that regulate activity at the NMJ participate in a network of heterotrimeric G-protein signaling pathways controlling the release of synaptic vesicles and/or dense-core vesicles (DCVs). At least four heterotrimeric G-proteins (Galphaq, Galpha12, Galphao, and Galphas) act within the motorneurons to control the activity of the NMJ. The Galphaq, Galpha12, and Galphao pathways converge to control production and destruction of the lipid-bound second messenger diacylglycerol (DAG) at sites of neurotransmitter release. DAG acts via at least two effectors, MUNC13 and PKC, to control the release of both neurotransmitters and neuropeptides from motorneurons. The Galphas pathway converges with the other three heterotrimeric G-protein pathways downstream of DAG to regulate neuropeptide release. Released neurotransmitters and neuropeptides then act to control contraction of the body-wall muscles to control locomotion. The lipids and proteins involved in these networks are conserved between C. elegans and mammals. Thus, the C. elegans NMJ acts as a model synapse to understand how neuronal activity in the human brain is regulated.
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Affiliation(s)
- Borja Perez-Mansilla
- MRC Cell Biology Unit, MRC Laboratory for Molecular Cell Biology and Department of Neurobiology, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Stephen Nurrish
- MRC Cell Biology Unit, MRC Laboratory for Molecular Cell Biology and Department of Neurobiology, Physiology and Pharmacology, University College London, London, United Kingdom
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23
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Bao H, Reist NE, Zhang B. The Drosophila epsin 1 is required for ubiquitin-dependent synaptic growth and function but not for synaptic vesicle recycling. Traffic 2008; 9:2190-205. [PMID: 18796008 DOI: 10.1111/j.1600-0854.2008.00832.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The ubiquitin-proteasome system plays an important role in synaptic development and function. However, many components of this system, and how they act to affect synapses, are still not well understood. In this study, we use the Drosophila neuromuscular junction to study the in vivo function of Liquid facets (Lqf), a homolog of mammalian epsin 1. Our data show that Lqf plays a novel role in synapse development and function. Contrary to prior models, Lqf is not required for clathrin-mediated endocytosis of synaptic vesicles. Lqf is required to maintain bouton size and shape and to sustain synapse growth by acting as a specific substrate of the deubiquitinating enzyme Fat facets. However, Lqf is not a substrate of the Highwire (Hiw) E3 ubiquitin ligase; neither is it required for synapse overgrowth in hiw mutants. Interestingly, Lqf converges on the Hiw pathway by negatively regulating transmitter release in the hiw mutant. These observations demonstrate that Lqf plays distinct roles in two ubiquitin pathways to regulate structural and functional plasticity of the synapse.
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Affiliation(s)
- Hong Bao
- Department of Zoology, University of Oklahoma, Norman, OK 73019, USA
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24
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Ghila L, Gomez M. The evolutionarily conserved gene LNP-1 is required for synaptic vesicle trafficking and synaptic transmission. Eur J Neurosci 2008; 27:621-30. [PMID: 18279315 DOI: 10.1111/j.1460-9568.2008.06049.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The control of vesicle-mediated transport in nerve cells is of great importance in the function, development and maintenance of synapse. In this paper, we characterize the new Caenorhabditis elegans gene, lnp-1. The lnp-1 gene is broadly distributed in many neuronal structures and its localization is dependent of the UNC-104/kinesin protein. Deletion mutations in lnp-1 result in increased resistance to aldicarb, an acetylcholinesterase inhibitor, and in locomotor defects. However, sensitivity to levamisole, a nicotinic agonist which, unlike aldicarb, only affects postsynaptic function, was similar to that of wild-type animals, suggesting a presynaptic function for LNP-1 in neurotransmission. The mislocalization of presynaptic proteins, such as synaptobrevin-1 or RAB-3, in lnp-1 mutants further supports this hypothesis. In summary, our studies suggest that LNP-1 plays a role in synaptogenesis by regulating vesicular transport or localization.
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Affiliation(s)
- Luiza Ghila
- Department of Zoology and Animal Biology and NCCR Frontiers in Genetics, University of Geneva, Sciences III, 30 quai Ernest-Ansermet, 1211 Genève 4, Switzerland
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25
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Wang W, Bouhours M, Gracheva EO, Liao EH, Xu K, Sengar AS, Xin X, Roder J, Boone C, Richmond JE, Zhen M, Egan SE. ITSN-1 controls vesicle recycling at the neuromuscular junction and functions in parallel with DAB-1. Traffic 2008; 9:742-54. [PMID: 18298590 DOI: 10.1111/j.1600-0854.2008.00712.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Intersectins (Itsn) are conserved EH and SH3 domain containing adaptor proteins. In Drosophila melanogaster, ITSN is required to regulate synaptic morphology, to facilitate efficient synaptic vesicle recycling and for viability. Here, we report our genetic analysis of Caenorhabditis elegans intersectin. In contrast to Drosophila, C. elegans itsn-1 protein null mutants are viable and display grossly normal locomotion and development. However, motor neurons in these mutants show a dramatic increase in large irregular vesicles and accumulate membrane-associated vesicles at putative endocytic hotspots, approximately 300 nm from the presynaptic density. This defect occurs precisely where endogenous ITSN-1 protein localizes in wild-type animals and is associated with a significant reduction in synaptic vesicle number and reduced frequency of endogenous synaptic events at neuromuscular junctions (NMJs). ITSN-1 forms a stable complex with EHS-1 (Eps15) and is expressed at reduced levels in ehs-1 mutants. Thus, ITSN-1 together with EHS-1, coordinate vesicle recycling at C. elegans NMJs. We also found that both itsn-1 and ehs-1 mutants show poor viability and growth in a Disabled (dab-1) null mutant background. These results show for the first time that intersectin and Eps15 proteins function in the same genetic pathway, and appear to function synergistically with the clathrin-coat-associated sorting protein, Disabled, for viability.
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Affiliation(s)
- Wei Wang
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children. 101 College Street, TMDT East Tower, Toronto, Ontario M5G 1L7, Canada
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26
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Bailly YJR, Castets F. Phocein: A potential actor in vesicular trafficking at Purkinje cell dendritic spines. CEREBELLUM (LONDON, ENGLAND) 2007; 6:344-52. [PMID: 17853115 DOI: 10.1080/14734220701225912] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Phocein is an intracellular protein highly expressed in neurons. It is the major partner of the striatin family members which are scaffolding proteins involved in signaling and trafficking. Due to its association with dynamin via direct interactions with nucleotide diphosphate kinase (NDPK) and EPS15, phocein has been implicated in vesicular trafficking, acting in particular in the endocytic process. This review focuses on immuno-cytochemical studies showing the strict localization of phocein in Purkinje cell dendritic spines involved in excitatory transmission in the cerebellum of postnatal and adult rodents. Immunogold labeling sometimes detects phocein in close vicinity with endocytic-like membrane profiles suggesting that phocein plays a role in endocytosis. Furthermore, co-localization of phocein and SG2NA within spines suggests that their interactions have a functional significance in the molecular cascades that underly membrane trafficking in post-synaptic structures. As the striatin family members are highly concentrated in dendritic spines, their interactions with phocein might be involved in mediating synaptic plasticity through spine remodeling by endocytosis.
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Affiliation(s)
- Yannick J R Bailly
- CInstitut des Neurosciences Cellulaires et Intégratives, Département Neurotransmission et Sécrétion Neuroendocrine, CNRS and Université Louis Pasteur, Strasbourg, France
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27
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Mahoney TR, Luo S, Nonet ML. Analysis of synaptic transmission in Caenorhabditis elegans using an aldicarb-sensitivity assay. Nat Protoc 2007; 1:1772-7. [PMID: 17487159 DOI: 10.1038/nprot.2006.281] [Citation(s) in RCA: 193] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Caenorhabditis elegans has emerged as a powerful model system for studying the biology of the synapse. Here we describe a widely used assay for synaptic transmission at the C. elegans neuromuscular junction. This protocol monitors the sensitivity of C. elegans to the paralyzing affects of an acetylcholinesterase inhibitor, aldicarb. Briefly, adult worms are incubated in the presence of aldicarb and scored for the time-course of aldicarb-induced paralysis. Animals harboring mutations in genes that affect synaptic transmission generally exhibit a change in their sensitivity to aldicarb (either increased sensitivity for enhancements in synaptic transmission or decreased sensitivity for blockage in synaptic transmission). This technique provides a simple assay for the accurate comparative analysis of synaptic transmission in multiple C. elegans strains. The protocol described can be performed relatively quickly and is a practical alternative to other techniques used to study synaptic transmission. This protocol can also be modified to follow the paralytic effects with other pharmacological reagents. The assay can be performed in about 3-6 hours depending on the severity of synaptic transmission defects.
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Affiliation(s)
- Timothy R Mahoney
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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28
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Rose S, Malabarba MG, Krag C, Schultz A, Tsushima H, Di Fiore PP, Salcini AE. Caenorhabditis elegans intersectin: a synaptic protein regulating neurotransmission. Mol Biol Cell 2007; 18:5091-9. [PMID: 17942601 DOI: 10.1091/mbc.e07-05-0460] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Intersectin is a multifunctional protein that interacts with components of the endocytic and exocytic pathways, and it is also involved in the control of actin dynamics. Drosophila intersectin is required for viability, synaptic development, and synaptic vesicle recycling. Here, we report the characterization of intersectin function in Caenorhabditis elegans. Nematode intersectin (ITSN-1) is expressed in the nervous system, and it is enriched in presynaptic regions. The C. elegans intersectin gene (itsn-1) is nonessential for viability. In addition, itsn-1-null worms do not display any evident phenotype, under physiological conditions. However, they display aldicarb-hypersensitivity, compatible with a negative regulatory role of ITSN-1 on neurotransmission. ITSN-1 physically interacts with dynamin and EHS-1, two proteins involved in synaptic vesicle recycling. We have previously shown that EHS-1 is a positive modulator of synaptic vesicle recycling in the nematode, likely through modulation of dynamin or dynamin-controlled pathways. Here, we show that ITSN-1 and EHS-1 have opposite effects on aldicarb sensitivity, and on dynamin-dependent phenotypes. Thus, the sum of our results identifies dynamin, or a dynamin-controlled pathway, as a potential target for the negative regulatory role of ITSN-1.
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Affiliation(s)
- Simon Rose
- Biotech Research and Innovation Centre, DK-2200 Copenhagen, Denmark
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29
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Koh TW, Korolchuk VI, Wairkar YP, Jiao W, Evergren E, Pan H, Zhou Y, Venken KJT, Shupliakov O, Robinson IM, O'Kane CJ, Bellen HJ. Eps15 and Dap160 control synaptic vesicle membrane retrieval and synapse development. ACTA ACUST UNITED AC 2007; 178:309-22. [PMID: 17620409 PMCID: PMC2064449 DOI: 10.1083/jcb.200701030] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Epidermal growth factor receptor pathway substrate clone 15 (Eps15) is a protein implicated in endocytosis, endosomal protein sorting, and cytoskeletal organization. Its role is, however, still unclear, because of reasons including limitations of dominant-negative experiments and apparent redundancy with other endocytic proteins. We generated Drosophila eps15-null mutants and show that Eps15 is required for proper synaptic bouton development and normal levels of synaptic vesicle (SV) endocytosis. Consistent with a role in SV endocytosis, Eps15 moves from the center of synaptic boutons to the periphery in response to synaptic activity. The endocytic protein, Dap160/intersectin, is a major binding partner of Eps15, and eps15 mutants phenotypically resemble dap160 mutants. Analyses of eps15 dap160 double mutants suggest that Eps15 functions in concert with Dap160 during SV endocytosis. Based on these data, we hypothesize that Eps15 and Dap160 promote the efficiency of endocytosis from the plasma membrane by maintaining high concentrations of multiple endocytic proteins, including dynamin, at synapses.
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Affiliation(s)
- Tong-Wey Koh
- Graduate Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA
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30
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Lubben NB, Sahlender DA, Motley AM, Lehner PJ, Benaroch P, Robinson MS. HIV-1 Nef-induced down-regulation of MHC class I requires AP-1 and clathrin but not PACS-1 and is impeded by AP-2. Mol Biol Cell 2007; 18:3351-65. [PMID: 17581864 PMCID: PMC1951775 DOI: 10.1091/mbc.e07-03-0218] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Major histocompatibility complex class I is down-regulated from the surface of human immunodeficiency virus (HIV)-1-infected cells by Nef, a virally encoded protein that is thought to reroute MHC-I to the trans-Golgi network (TGN) in a phosphofurin acidic cluster sorting protein (PACS) 1, adaptor protein (AP)-1, and clathrin-dependent manner. More recently, an alternative model has been proposed, in which Nef uses AP-1 to direct MHC-I to endosomes and lysosomes. Here, we show that knocking down either AP-1 or clathrin with small interfering RNA inhibits the down-regulation of HLA-A2 (an MHC-I isotype) by Nef in HeLa cells. However, knocking down PACS-1 has no effect, not only on Nef-induced down-regulation of HLA-A2 but also on the localization of other proteins containing acidic cluster motifs. Surprisingly, knocking down AP-2 actually enhances Nef activity. Immuno-electron microscopy labeling of Nef-expressing cells indicates that HLA-A2 is rerouted not to the TGN, but to endosomes. In AP-2-depleted cells, more of the HLA-A2 localizes to the inner vesicles of multivesicular bodies. We propose that depleting AP-2 potentiates Nef activity by altering the membrane composition and dynamics of endosomes and causing increased delivery of HLA-A2 to a prelysosomal compartment.
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Affiliation(s)
- Nienke B. Lubben
- *University of Cambridge, Cambridge Institute for Medical Research, Cambridge CB2 0XY, United Kingdom; and
| | - Daniela A. Sahlender
- *University of Cambridge, Cambridge Institute for Medical Research, Cambridge CB2 0XY, United Kingdom; and
| | - Alison M. Motley
- *University of Cambridge, Cambridge Institute for Medical Research, Cambridge CB2 0XY, United Kingdom; and
| | - Paul J. Lehner
- *University of Cambridge, Cambridge Institute for Medical Research, Cambridge CB2 0XY, United Kingdom; and
| | | | - Margaret S. Robinson
- *University of Cambridge, Cambridge Institute for Medical Research, Cambridge CB2 0XY, United Kingdom; and
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31
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Bakowska JC, Jupille H, Fatheddin P, Puertollano R, Blackstone C. Troyer syndrome protein spartin is mono-ubiquitinated and functions in EGF receptor trafficking. Mol Biol Cell 2007; 18:1683-92. [PMID: 17332501 PMCID: PMC1855030 DOI: 10.1091/mbc.e06-09-0833] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Troyer syndrome is an autosomal recessive hereditary spastic paraplegia caused by mutation in the spartin (SPG20) gene, which encodes a widely expressed protein of unknown function. This mutation results in premature protein truncation and thus might signify a loss-of-function disease mechanism. In this study, we have found that spartin is mono-ubiquitinated and functions in degradation of the epidermal growth factor receptor (EGFR). Upon EGF stimulation, spartin translocates from the cytoplasm to the plasma membrane and colocalizes with internalized EGF-Alexa. Knockdown of spartin by small interfering RNA decreases the rate of EGFR degradation and also affects EGFR internalization, recycling, or both. Furthermore, overexpression of spartin results in a prominent decrease in EGFR degradation. Taken together, our data suggest that spartin is involved in the intracellular trafficking of EGFR and that impaired endocytosis may underlie the pathogenesis of Troyer syndrome.
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Affiliation(s)
- Joanna C. Bakowska
- *Cellular Neurology Unit, National Institute of Neurological Disorders and Stroke, and
| | - Henri Jupille
- *Cellular Neurology Unit, National Institute of Neurological Disorders and Stroke, and
| | - Parvin Fatheddin
- *Cellular Neurology Unit, National Institute of Neurological Disorders and Stroke, and
| | - Rosa Puertollano
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Craig Blackstone
- *Cellular Neurology Unit, National Institute of Neurological Disorders and Stroke, and
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32
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Maldonado-Báez L, Wendland B. Endocytic adaptors: recruiters, coordinators and regulators. Trends Cell Biol 2006; 16:505-13. [PMID: 16935508 DOI: 10.1016/j.tcb.2006.08.001] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2006] [Revised: 07/18/2006] [Accepted: 08/14/2006] [Indexed: 02/02/2023]
Abstract
Clathrin-dependent endocytosis allows cells to bring plasma membrane and extracellular molecules into the cell. Forming a clathrin-coated vesicle requires the sequential action of numerous factors, beginning with endocytic adaptors. Adaptors are thought to initiate the process in two ways: by selecting cargo for packaging into the vesicle and assembling the clathrin coat and other components necessary to shape the vesicle. Here, we review recent work focusing on the sequential and cooperative interactions of adaptors with their binding partners, and how adaptors contribute to initial stages of endocytic internalization. The regulation of adaptors might be a key step for controlling endocytosis, and thus aid in homeostasis and cell physiology.
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Affiliation(s)
- Lymarie Maldonado-Báez
- The Johns Hopkins University, Department of Biology, 3400 N. Charles St, Baltimore, MD 21218, USA
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33
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Robay D, Patel H, Simpson MA, Brown NA, Crosby AH. Endogenous spartin, mutated in hereditary spastic paraplegia, has a complex subcellular localization suggesting diverse roles in neurons. Exp Cell Res 2006; 312:2764-77. [PMID: 16781711 DOI: 10.1016/j.yexcr.2006.05.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2006] [Revised: 05/03/2006] [Accepted: 05/05/2006] [Indexed: 11/28/2022]
Abstract
Mutation of spartin (SPG20) underlies a complicated form of hereditary spastic paraplegia, a disorder principally defined by the degeneration of upper motor neurons. Using a polyclonal antibody against spartin to gain insight into the function of the endogenous molecule, we show that the endogenous molecule is present in two main isoforms of 85 kDa and 100 kDa, and 75 kDa and 85 kDa in human and murine, respectively, with restricted subcellular localization. Immunohistochemical studies on human and mouse embryo sections and in vitro cell studies indicate that spartin is likely to possess both nuclear and cytoplasmic functions. The nuclear expression of spartin closely mirrors that of the snRNP (small nuclear ribonucleoprotein) marker alpha-Sm, a component of the spliceosome. Spartin is also enriched at the centrosome within mitotic structures. Notably we show that spartin protein undergoes dynamic positional changes in differentiating human SH-SY5Y cells. In undifferentiated non-neuronal cells, spartin displays a nuclear and diffuse cytosolic profile, whereas spartin transiently accumulates in the trans-Golgi network and subsequently decorates discrete puncta along neurites in terminally differentiated neuroblastic cells. Investigation of these spartin-positive vesicles reveals that a large proportion colocalizes with the synaptic vesicle marker synaptotagmin. Spartin is also enriched in synaptic-like structures and in synaptic vesicle-enriched fraction.
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Affiliation(s)
- Dimitri Robay
- Medical Genetics, St. George's, University of London, Cranmer Terrace, London SW17 0RE, UK
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34
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Abraham C, Hutter H, Palfreyman MT, Spatkowski G, Weimer RM, Windoffer R, Jorgensen EM, Leube RE. Synaptic tetraspan vesicle membrane proteins are conserved but not needed for synaptogenesis and neuronal function in Caenorhabditis elegans. Proc Natl Acad Sci U S A 2006; 103:8227-32. [PMID: 16698939 PMCID: PMC1570102 DOI: 10.1073/pnas.0509400103] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Tetraspan vesicle membrane proteins (TVPs) comprise a major portion of synaptic vesicle proteins, yet their contribution to the synaptic vesicle cycle is poorly understood. TVPs are grouped in three mammalian gene families: physins, gyrins, and secretory carrier-associated membrane proteins (SCAMPs). In Caenorhabditis elegans, only a single member of each of these families exists. These three nematode TVPs colocalize to the same vesicular compartment when expressed in mammalian cells, suggesting that they could serve overlapping functions. To examine their function, C. elegans null mutants were isolated for each gene, and a triple mutant was generated. Surprisingly, these animals develop normally and exhibit normal neuronal architecture and synaptic contacts. In addition, functions of the motor and sensory systems are normal as determined by pharmacological, chemotaxis, and thermotaxis assays. Finally, direct electrophysiological analysis of the neuromuscular junction revealed no phenotype in the TVP mutants. We therefore conclude that TVPs are not needed for the basic neuronal machinery and instead may contribute to subtle higher order functions.
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Affiliation(s)
- Christian Abraham
- *Department of Anatomy and Cell Biology, Johannes Gutenberg University, Becherweg 13, 55128 Mainz, Germany
| | - Harald Hutter
- Max-Planck-Institut für Medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Mark T. Palfreyman
- Department of Biology and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT 84112-0840; and
| | - Gabriele Spatkowski
- *Department of Anatomy and Cell Biology, Johannes Gutenberg University, Becherweg 13, 55128 Mainz, Germany
| | - Robby M. Weimer
- Department of Biology and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT 84112-0840; and
- Biologie Cellulaire de la Synapse, Ecole Normale Supérieure, 75005 Paris, France
| | - Reinhard Windoffer
- *Department of Anatomy and Cell Biology, Johannes Gutenberg University, Becherweg 13, 55128 Mainz, Germany
| | - Erik M. Jorgensen
- Department of Biology and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT 84112-0840; and
| | - Rudolf E. Leube
- *Department of Anatomy and Cell Biology, Johannes Gutenberg University, Becherweg 13, 55128 Mainz, Germany
- **To whom correspondence should be addressed. E-mail:
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35
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Haeberlé AM, Castets F, Bombarde G, Baillat G, Bailly Y. Immunogold localization of phocein in dendritic spines. J Comp Neurol 2006; 495:336-50. [PMID: 16440294 DOI: 10.1002/cne.20895] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Phocein, a widely expressed intracellular protein involved in clathrin- and dynamin-dependent membrane dynamics, has been shown to interact with members of the striatin family of proteins, striatin, SG2NA, and zinedin. Immunogold labeling was performed to assess subcellular localization of phocein in neurons of the rodent cerebellar cortex and hippocampal Ammon's horn. Most of the phocein-bound gold particles were located within dendritic thorns and spines of the cerebellar Purkinje cells and hippocampal pyramidal neurons, as observed previously for striatin in striatal neurons. The postsynaptic profiles containing phocein were engaged in asymmetric synapses with the main types of afferents in the cerebellum and in the hippocampus. In the cerebellum, phocein-bound immunogold particle numbers ranged from 1-20 in approximately 50% of the Purkinje cell spines. In these spines most of the immunogold particles were found in the neuroplasm ( approximately 70%) and on nonsynaptic plasma membrane domains and related structures such as endocytic-like profiles ( approximately 18%). As soon as the first postnatal week, phocein was detected in the Purkinje cell somatic and dendritic thorns making asymmetric synapses with climbing fibers. During the following weeks the protein was located in the dendritic spines, as observed in the adult molecular layer. Finally, double immunogold labeling revealed a distribution of phocein and SG2NA suggesting that the two proteins could interact in the Purkinje cell spines. The early postnatal expression of phocein, a protein involved in membrane dynamics, suggests that it may have functional relevance in dendritic remodeling during development and potentially in spine plasticity during adulthood.
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Affiliation(s)
- Anne-Marie Haeberlé
- Neurotransmission et Sécrétion Neuroendocrine Unité Propre de Recherche 2356 Centre National de la Recherche Scientifique, IFR37 des Neurosciences, 67084 Strasbourg, France
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36
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Majumdar A, Ramagiri S, Rikhy R. Drosophila homologue of Eps15 is essential for synaptic vesicle recycling. Exp Cell Res 2006; 312:2288-98. [PMID: 16709407 DOI: 10.1016/j.yexcr.2006.03.030] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2006] [Revised: 03/15/2006] [Accepted: 03/23/2006] [Indexed: 10/24/2022]
Abstract
The mammalian protein Eps15 is phosphorylated by EGF receptor tyrosine kinase and has been shown to interact with several components of the endocytic machinery. We have identified a hypomorphic Eps15 mutant in Drosophila which shows reversible paralysis and an altered physiology at restrictive temperatures. In addition, the temperature-sensitive paralytic defect of shibire mutant is enhanced by this mutant. Eps15 is enriched in the larval neuromuscular junction in endocytic 'hot spots' in a pattern similar to Dynamin. Eps15 mutants show a decrease in the alpha-Adaptin levels at the larval neuromuscular junction synapse. Genetic and biochemical studies of interactions with components of the endocytic machinery suggest that Eps15 has an important role in synaptic vesicle recycling and regulates recruitment of alpha-Adaptin.
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Affiliation(s)
- Amitabha Majumdar
- Department of Biological Sciences, Tata Institute of Fundamental Research, Colaba Mumbai 400005, India.
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37
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Augustine GJ, Morgan JR, Villalba-Galea CA, Jin S, Prasad K, Lafer EM. Clathrin and synaptic vesicle endocytosis: studies at the squid giant synapse. Biochem Soc Trans 2006; 34:68-72. [PMID: 16417485 PMCID: PMC4442616 DOI: 10.1042/bst0340068] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The role of clathrin-mediated endocytosis in SV (synaptic vesicle) recycling has been studied by combining molecular biology, physiology and electron microscopy at the squid giant synapse. Procedures that prevent clathrin from assembling into membrane coats, such as impairment of binding of the AP180 and AP-2 adaptor proteins, completely prevent membrane budding during endocytosis. These procedures also reduce exocytosis, presumably an indirect effect of a reduction in the number of SVs following block of endocytosis. Disrupting the binding of auxilin to Hsc70 (heat-shock cognate 70) prevents clathrin-coated vesicles from uncoating and also disrupts SV recycling. Taken together, these results indicate that a clathrin-dependent pathway is the primary means of SV recycling at this synapse under physiological conditions.
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Affiliation(s)
- G J Augustine
- Department of Neurobiology, Duke University School of Medicine, Box 3209, Durham, NC 27710, USA.
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38
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Tosoni D, Puri C, Confalonieri S, Salcini AE, De Camilli P, Tacchetti C, Di Fiore PP. TTP specifically regulates the internalization of the transferrin receptor. Cell 2006; 123:875-88. [PMID: 16325581 DOI: 10.1016/j.cell.2005.10.021] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2005] [Revised: 08/10/2005] [Accepted: 10/13/2005] [Indexed: 10/25/2022]
Abstract
Different plasma membrane receptors are internalized through saturable/noncompetitive pathways, suggesting cargo-specific regulation. Here, we report that TTP (SH3BP4), a SH3-containing protein, specifically regulates the internalization of the transferrin receptor (TfR). TTP interacts with endocytic proteins, including clathrin, dynamin, and the TfR, and localizes selectively to TfR-containing coated-pits (CCP) and -vesicles (CCV). Overexpression of TTP specifically inhibits TfR internalization, and causes the formation of morphologically aberrant CCP, which are probably fission impaired. This effect is mediated by the SH3 of TTP, which can bind to dynamin, and it is rescued by overexpression of dynamin. Functional ablation of TTP causes a reduction in TfR internalization, and reduced cargo loading and size of TfR-CCV. Tyrosine phosphorylation of either TTP or dynamin prevents their interaction, pointing to a possible mechanism of exclusion of TTP from some CCP. Thus, TTP might represent one of the long sought for molecules that allow cargo-specific control of clathrin endocytosis.
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Affiliation(s)
- Daniela Tosoni
- IFOM, Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milan, Italy
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Tang H, Rompani SB, Atkins JB, Zhou Y, Osterwalder T, Zhong W. Numb proteins specify asymmetric cell fates via an endocytosis- and proteasome-independent pathway. Mol Cell Biol 2005; 25:2899-909. [PMID: 15798180 PMCID: PMC1069617 DOI: 10.1128/mcb.25.8.2899-2909.2005] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2004] [Revised: 12/20/2004] [Accepted: 01/10/2005] [Indexed: 12/25/2022] Open
Abstract
Numb proteins are evolutionarily conserved signaling molecules that make the daughter cells different after asymmetric divisions by segregating to only one daughter. They contain distinct binding motifs for alpha-adaptin (alpha-Ada) and proteins with Eps15 homology (EH) domains, which regulate endocytosis, and for E3 ubiquitin ligases, which target proteins for proteasome-mediated degradation. In Drosophila melanogaster, Numb acts by inhibiting Notch activity to cause a bias in Notch-mediated cell-cell communication. These findings have led to the hypothesis that Numb modulates Notch signaling by using endocytosis and proteasomes to directly reduce Notch protein levels at the cell surface. Here we show that two Drosophila EH proteins, Eps15 homologue 1 (EH1) and the dynamin-associated 160-kDa protein (Dap160), negatively regulate Notch signaling. However, neither elimination of the binding motifs for endocytic proteins nor simultaneous reduction of proteasome activity affects the activity of Numb proteins. Our findings indicate that an endocytosis- and proteasome-independent pathway may mediate Numb signaling in asymmetric cell fate specification.
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Affiliation(s)
- Haiyan Tang
- Department of Molecular, Cellular and Developmental Biology, Yale University, P.O. Box 208103, New Haven, CT 06520, USA
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40
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Sigismund S, Woelk T, Puri C, Maspero E, Tacchetti C, Transidico P, Di Fiore PP, Polo S. Clathrin-independent endocytosis of ubiquitinated cargos. Proc Natl Acad Sci U S A 2005; 102:2760-5. [PMID: 15701692 PMCID: PMC549482 DOI: 10.1073/pnas.0409817102] [Citation(s) in RCA: 642] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Plasma membrane receptors can be endocytosed through clathrin-dependent and clathrin-independent pathways. Here, we show that the epidermal growth factor (EGF) receptor (EGFR), when stimulated with low doses of EGF, is internalized almost exclusively through the clathrin pathway, and it is not ubiquitinated. At higher concentrations of ligand, however, a substantial fraction of the receptor is endocytosed through a clathrin-independent, lipid raft-dependent route, as the receptor becomes ubiquitinated. An ubiquitination-impaired EGFR mutant was internalized through the clathrin pathway, whereas an EGFR/ubiquitin chimera, that can signal solely through its ubiquitin (Ub) moiety, was internalized exclusively by the non-clathrin pathway. Non-clathrin internalization of ubiquitinated EGFR depends on its interaction with proteins harboring the Ub-interacting motif, as shown through the ablation of three Ub-interacting motif-containing proteins, eps15, eps15R, and epsin. Thus, eps15s and epsin perform an important function in coupling ubiquitinated cargo to clathrin-independent internalization.
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Affiliation(s)
- Sara Sigismund
- Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milan, Italy
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41
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Croce A, Cassata G, Disanza A, Gagliani MC, Tacchetti C, Malabarba MG, Carlier MF, Scita G, Baumeister R, Di Fiore PP. A novel actin barbed-end-capping activity in EPS-8 regulates apical morphogenesis in intestinal cells of Caenorhabditis elegans. Nat Cell Biol 2004; 6:1173-9. [PMID: 15558032 DOI: 10.1038/ncb1198] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2004] [Accepted: 10/13/2004] [Indexed: 01/17/2023]
Abstract
Redundant gene function frequently hampers investigations of the physiological roles of mammalian proteins. This is the case for Eps8, a receptor tyrosine kinase (RTK) substrate that participates in the activation of the Rac-specific guanine nucleotide-exchange function of Sos1 (refs 2-5), thereby regulating actin remodelling by RTKs. EPS8-knockout mice, however, exhibit no evident phenotype, owing to the redundant function of three other EPS8-related genes. Here we show that in the nematode Caenorhabditis elegans, only one orthologue of the EPS8 gene exists, which gives rise to two alternatively spliced isoforms, EPS-8A and EPS-8B, differing at their carboxyl termini. In the nematode, eps-8 is essential for embryonic development. Furthermore, EPS-8A, but not EPS-8B, is specifically required for proper apical morphogenesis in the intestinal cells. This latter phenotype could be precisely correlated with a previously unknown actin barbed-end-capping activity, which is present in the C terminus of the EPS-8A isoform. Therefore, nematode genetics allowed not only the unmasking of distinct EPS-8-linked phenotypes, but also the definition of a novel function for this molecule in actin dynamics.
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Affiliation(s)
- Assunta Croce
- IFOM Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milan, Italy
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42
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Pöggeler S, Kück U. A WD40 repeat protein regulates fungal cell differentiation and can be replaced functionally by the mammalian homologue striatin. EUKARYOTIC CELL 2004; 3:232-40. [PMID: 14871953 PMCID: PMC329509 DOI: 10.1128/ec.3.1.232-240.2004] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Fruiting body development in fungi is a complex cellular differentiation process that is controlled by more than 100 developmental genes. Mutants of the filamentous fungus Sordaria macrospora showing defects in fruiting body formation are pertinent sources for the identification of components of this multicellular differentiation process. Here we show that the sterile mutant pro11 carries a defect in the pro11 gene encoding a multimodular WD40 repeat protein. Complementation analysis indicates that the wild-type gene or C-terminally truncated versions of the wild-type protein are able to restore the fertile phenotype in mutant pro11. PRO11 shows significant homology to several vertebrate WD40 proteins, such as striatin and zinedin, which seem to be involved in Ca2+-dependent signaling in cells of the central nervous system and are supposed to function as scaffolding proteins linking signaling and eukaryotic endocytosis. Cloning of a mouse cDNA encoding striatin allowed functional substitution of the wild-type protein with restoration of fertility in mutant pro11. Our data strongly suggest that an evolutionarily conserved cellular process controlling eukaryotic cell differentiation may regulate fruiting body formation.
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Affiliation(s)
- Stefanie Pöggeler
- Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität Bochum, 44780 Bochum, Germany
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Koh TW, Verstreken P, Bellen HJ. Dap160/Intersectin Acts as a Stabilizing Scaffold Required for Synaptic Development and Vesicle Endocytosis. Neuron 2004; 43:193-205. [PMID: 15260956 DOI: 10.1016/j.neuron.2004.06.029] [Citation(s) in RCA: 189] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2004] [Revised: 05/21/2004] [Accepted: 06/16/2004] [Indexed: 11/24/2022]
Abstract
We describe the isolation of mutations in dynamin-associated protein 160 kDa (dap160), the Drosophila homolog of intersectin, a putative adaptor for proteins involved in endocytosis, cytoskeletal regulation, and signaling. We show that partial loss-of-function mutants display temperature-sensitive (ts) paralysis, whereas null mutants show ts defects in endocytosis. Loss-of-function mutants exhibit bouton overgrowth at larval neuromuscular junctions (NMJs), but evoked neurotransmission is normal. Mutant NMJs show a mild endocytic defect at 22 degrees C, which is strongly enhanced at 34 degrees C. The levels of dynamin, synaptojanin and endophilin are severely reduced in dap160 mutant NMJs, suggesting that Dap160 serves to stabilize an endocytic macromolecular complex. Electron microscopy reveals fewer vesicles, aberrant large vesicles, and an accumulation of endocytic intermediates at active and periactive zones in mutant terminals. Our data suggest that Dap160, like dynamin, is involved in synaptic vesicle retrieval at active and periactive zones.
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Affiliation(s)
- Tong-Wey Koh
- Program in Developmental Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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44
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Tijsterman M, May RC, Simmer F, Okihara KL, Plasterk RHA. Genes required for systemic RNA interference in Caenorhabditis elegans. Curr Biol 2004; 14:111-6. [PMID: 14738731 DOI: 10.1016/j.cub.2003.12.029] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
RNA interference (RNAi) in the nematode worm, Caenorhabditis elegans, occurs systemically. Double-stranded RNA (dsRNA) provided in the diet can be absorbed from the gut lumen and distributed throughout the body, triggering RNAi in tissues that are not exposed to the initial dsRNA trigger. This is in marked contrast to other animals, in which RNAi does not spread from targeted tissues to neighboring cells. Here, we report the characterization of mutants defective in the systemic aspect of RNAi, but not in the core RNAi process itself. Analysis of these mutants suggests that dsRNA uptake is a specific process involving several unique proteins.
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Affiliation(s)
- Marcel Tijsterman
- Hubrecht Laboratory, Centre for Biomedical Genetics, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
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45
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Abstract
Exogenously and endogenously originated signals are propagated within the cell by functional and physical networks of proteins, leading to numerous biological outcomes. Many protein-protein interactions take place between binding domains and short peptide motifs. Frequently, these interactions are inducible by upstream signaling events, in which case one of the two binding surfaces may be created by a posttranslational modification. Here, we discuss two protein networks. One, the EH-network, is based on the Eps15 homology (EH) domain, which binds to peptides containing the sequence Asp-Pro-Phe (NPF). The other, which we define as the monoubiquitin (mUb) network, relies on monoubiquitination, which is emerging as an important posttranslational modification that regulates protein function. Both networks were initially implicated in the control of plasma membrane receptor endocytosis and in the regulation of intracellular trafficking routes. The ramifications of these two networks, however, appear to extend into many other aspects of cell physiology as well, such as transcriptional regulation, actin cytoskeleton remodeling, and DNA repair. The focus of this review is to integrate available knowledge of the EH- and mUb networks with predictions of genetic and physical interactions stemming from functional genomics approaches.
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Affiliation(s)
- Simona Polo
- Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milan, Italy
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Morgan JR, Prasad K, Jin S, Augustine GJ, Lafer EM. Eps15 homology domain-NPF motif interactions regulate clathrin coat assembly during synaptic vesicle recycling. J Biol Chem 2003; 278:33583-92. [PMID: 12807910 DOI: 10.1074/jbc.m304346200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Although genetic and biochemical studies suggest a role for Eps15 homology domain containing proteins in clathrin-mediated endocytosis, the specific functions of these proteins have been elusive. Eps15 is found at the growing edges of clathrin-coated pits, leading to the hypothesis that it participates in the formation of coated vesicles. We have evaluated this hypothesis by examining the effect of Eps15 on clathrin assembly. We found that although Eps15 has no intrinsic ability to assemble clathrin, it potently stimulates the ability of the clathrin adaptor protein, AP180, to assemble clathrin at physiological pH. We have also defined the binding sites for Eps15 on squid AP180. These sites contain an NPF motif, and peptides derived from these binding sites inhibit the ability of Eps15 to stimulate clathrin assembly in vitro. Furthermore, when injected into squid giant presynaptic nerve terminals, these peptides inhibit the formation of clathrin-coated pits and coated vesicles during synaptic vesicle endocytosis. This is consistent with the hypothesis that Eps15 regulates clathrin coat assembly in vivo, and indicates that interactions between Eps15 homology domains and NPF motifs are involved in clathrin-coated vesicle formation during synaptic vesicle recycling.
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Affiliation(s)
- Jennifer R Morgan
- Duke University School of Medicine, Department of Neurobiology, Durham, North Carolina 27710, USA
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47
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Abstract
Eukaryotic cells use actin polymerization to change shape, move, and internalize extracellular materials by phagocytosis and endocytosis, and to form contractile structures. In addition, several pathogens have evolved to use host cell actin assembly for attachment, internalization, and cell-to-cell spread. Although cells possess multiple mechanisms for initiating actin polymerization, attention in the past five years has focused on the regulation of actin nucleation-the formation of new actin filaments from actin monomers. The Arp2/3 complex and the multiple nucleation-promoting factors (NPFs) that regulate its activity comprise the only known cellular actin-nucleating factors and may represent a universal machine, conserved across eukaryotic phyla, that nucleates new actin filaments for various cellular structures with numerous functions. This review focuses on our current understanding of the mechanism of actin nucleation by the Arp2/3 complex and NPFs and how these factors work with other cytoskeletal proteins to generate structurally and functionally diverse actin arrays in cells.
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Affiliation(s)
- Matthew D Welch
- Department of Molecular and Cell Biology, 301 LSA, University of California, Berkeley 94720-3200, USA.
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Richmond JE, Broadie KS. The synaptic vesicle cycle: exocytosis and endocytosis in Drosophila and C. elegans. Curr Opin Neurobiol 2002; 12:499-507. [PMID: 12367628 DOI: 10.1016/s0959-4388(02)00360-4] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Advances in the study of Drosophila melanogaster and Caenorhabditis elegans have provided key insights into the processes of neurotransmission and neuromodulation. Work in the past year has revealed that Unc-13 and Rab3a-interacting molecule regulate the conformational state of syntaxin to prime synaptic vesicle fusion. Analyses of synaptotagmin support its role as a putative calcium sensor triggering vesicular fusion and highlight the possible role of SNARE complex oligomerization in the fusion mechanism. Characterization of endophilin mutants demonstrates that kiss-and-run endocytosis is a major component of synaptic vesicle recycling. In neuromodulation, dcaps mutants provide the first genetic insight into possible roles of the CAPS protein in mediating dense core vesicle fusion and modulating synaptic vesicle fusion.
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Affiliation(s)
- Janet E Richmond
- Department of Biological Sciences, University of Illinois, 840 West Taylor Street, Chicago, Illinois 60607, USA
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Baillat G, Gaillard S, Castets F, Monneron A. Interactions of phocein with nucleoside-diphosphate kinase, Eps15, and Dynamin I. J Biol Chem 2002; 277:18961-6. [PMID: 11872741 DOI: 10.1074/jbc.m108818200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phocein, an intracellular protein interacting with striatin, bears a few homologies with the sigma-subunits of clathrin adaptor proteins (Baillat, G., Moqrich, A., Castets, F., Baude, A., Bailly, Y., Benmerah, A., and Monneron, A. (2001) Mol. Biol. Cell 12, 663-673). Using phocein as a bait in a yeast two-hybrid screen, we identified two novel interacting proteins, nucleoside-diphosphate kinase (NDPK) and Eps15. Immunoprecipitation and pull-down experiments involving native and/or recombinant phocein and, respectively, NDPK and Eps15, biochemically validated their interactions. NDPK and Eps15 were recently shown to be functional neighbors of dynamin. Dynamin I is shown here to directly interact with NDPK through its C-terminal proline-rich domain, whereas recombinant phocein associates with native dynamin I. Immunocytochemical studies of rat embryonic hippocampal neurons demonstrated partial co-localization of phocein and dynamin I. Phocein thus appears to be a component of the complexes involved in some steps of the vesicular traffic machinery.
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Affiliation(s)
- Gilbert Baillat
- INSERM U464, Faculté de Médecine Nord, Bd. Pierre Dramard, 13916 Marseille Cedex 20, France
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50
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Panda S, Antoch MP, Miller BH, Su AI, Schook AB, Straume M, Schultz PG, Kay SA, Takahashi JS, Hogenesch JB. Coordinated transcription of key pathways in the mouse by the circadian clock. Cell 2002; 109:307-20. [PMID: 12015981 DOI: 10.1016/s0092-8674(02)00722-5] [Citation(s) in RCA: 1749] [Impact Index Per Article: 79.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
In mammals, circadian control of physiology and behavior is driven by a master pacemaker located in the suprachiasmatic nuclei (SCN) of the hypothalamus. We have used gene expression profiling to identify cycling transcripts in the SCN and in the liver. Our analysis revealed approximately 650 cycling transcripts and showed that the majority of these were specific to either the SCN or the liver. Genetic and genomic analysis suggests that a relatively small number of output genes are directly regulated by core oscillator components. Major processes regulated by the SCN and liver were found to be under circadian regulation. Importantly, rate-limiting steps in these various pathways were key sites of circadian control, highlighting the fundamental role that circadian clocks play in cellular and organismal physiology.
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Affiliation(s)
- Satchidananda Panda
- The Genomics Institute of the Novartis Research Foundation, San Diego, California 92121, USA
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