1
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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2
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Brina D, Miluzio A, Ricciardi S, Clarke K, Davidsen PK, Viero G, Tebaldi T, Offenhäuser N, Rozman J, Rathkolb B, Neschen S, Klingenspor M, Wolf E, Gailus-Durner V, Fuchs H, Hrabe de Angelis M, Quattrone A, Falciani F, Biffo S. eIF6 coordinates insulin sensitivity and lipid metabolism by coupling translation to transcription. Nat Commun 2015; 6:8261. [PMID: 26383020 PMCID: PMC4595657 DOI: 10.1038/ncomms9261] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 08/04/2015] [Indexed: 02/07/2023] Open
Abstract
Insulin regulates glycaemia, lipogenesis and increases mRNA translation. Cells with reduced eukaryotic initiation factor 6 (eIF6) do not increase translation in response to insulin. The role of insulin-regulated translation is unknown. Here we show that reduction of insulin-regulated translation in mice heterozygous for eIF6 results in normal glycaemia, but less blood cholesterol and triglycerides. eIF6 controls fatty acid synthesis and glycolysis in a cell autonomous fashion. eIF6 acts by exerting translational control of adipogenic transcription factors like C/EBPβ, C/EBPδ and ATF4 that have G/C rich or uORF sequences in their 5' UTR. The outcome of the translational activation by eIF6 is a reshaping of gene expression with increased levels of lipogenic and glycolytic enzymes. Finally, eIF6 levels modulate histone acetylation and amounts of rate-limiting fatty acid synthase (Fasn) mRNA. Since obesity, type 2 diabetes, and cancer require a Fasn-driven lipogenic state, we propose that eIF6 could be a therapeutic target for these diseases.
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Affiliation(s)
- Daniela Brina
- INGM, ‘Romeo ed Enrica Invernizzi', 20122 Milano, Italy
| | | | | | - Kim Clarke
- Centre for Computational Biology and Modeling, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Peter K. Davidsen
- Centre for Computational Biology and Modeling, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Gabriella Viero
- Institute of Biophysics, 38123 Trento, Italy
- Centre for Integrative Biology, University of Trento, 38123 Trento, Italy
| | - Toma Tebaldi
- Centre for Integrative Biology, University of Trento, 38123 Trento, Italy
| | | | - Jan Rozman
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
| | - Birgit Rathkolb
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
- Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilian-University, 81377 Munich, Germany
| | - Susanne Neschen
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
| | - Martin Klingenspor
- Else Kröner-Fresenius Center, Technische Universität München, 85354 Freising, Germany
| | - Eckhard Wolf
- Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilian-University, 81377 Munich, Germany
| | - Valerie Gailus-Durner
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
| | - Helmut Fuchs
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
| | - Martin Hrabe de Angelis
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
- Center of Life and Food Sciences Weihenstephan, Technische Universität München, 85354 Freising, Germany
- German Center for Diabetes Research, 85764 Neuherberg, Germany
| | | | - Francesco Falciani
- Centre for Computational Biology and Modeling, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Stefano Biffo
- INGM, ‘Romeo ed Enrica Invernizzi', 20122 Milano, Italy
- Department of Biosciences, University of Milan, 20133 Milan, Italy
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3
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Fregnan F, Petrov V, Garzotto D, De Marchis S, Offenhäuser N, Grosso E, Chiorino G, Perroteau I, Gambarotta G. Eps8 involvement in neuregulin1-ErbB4 mediated migration in the neuronal progenitor cell line ST14A. Exp Cell Res 2011; 317:757-69. [DOI: 10.1016/j.yexcr.2011.01.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Revised: 12/23/2010] [Accepted: 01/25/2011] [Indexed: 10/18/2022]
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4
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Tocchetti A, Ekalle Soppo CB, Zani F, Bianchi F, Gagliani MC, Pozzi B, Rozman J, Elvert R, Ehrhardt N, Rathkolb B, Moerth C, Horsch M, Fuchs H, Gailus-Durner V, Beckers J, Klingenspor M, Wolf E, de Angelis MH, Scanziani E, Tacchetti C, Scita G, Di Fiore PP, Offenhäuser N. Loss of the actin remodeler Eps8 causes intestinal defects and improved metabolic status in mice. PLoS One 2010; 5:e9468. [PMID: 20209148 PMCID: PMC2830459 DOI: 10.1371/journal.pone.0009468] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Accepted: 02/05/2010] [Indexed: 01/06/2023] Open
Abstract
Background In a variety of organisms, including mammals, caloric restriction improves metabolic status and lowers the incidence of chronic-degenerative diseases, ultimately leading to increased lifespan. Methodology/Principal Findings Here we show that knockout mice for Eps8, a regulator of actin dynamics, display reduced body weight, partial resistance to age- or diet-induced obesity, and overall improved metabolic status. Alteration in the liver gene expression profile, in behavior and metabolism point to a calorie restriction-like phenotype in Eps8 knockout mice. Additionally, and consistent with a calorie restricted metabolism, Eps8 knockout mice show increased lifespan. The metabolic alterations in Eps8 knockout mice correlated with a significant reduction in intestinal fat absorption presumably caused by a 25% reduction in intestinal microvilli length. Conclusions/Significance Our findings implicate actin dynamics as a novel variable in the determination of longevity. Additionally, our observations suggest that subtle differences in energy balance can, over time, significantly affect bodyweight and metabolic status in mice.
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Affiliation(s)
| | | | - Fabio Zani
- Fondazione Instituto FIRC di Oncologia Molecolare, Milan, Italy
| | - Fabrizio Bianchi
- Fondazione Instituto FIRC di Oncologia Molecolare, Milan, Italy
- Dipartimento di Medicina, Chirurgia ed Odontoiatria, Universita' degli Studi di Milano, Milan, Italy
| | - Maria Cristina Gagliani
- Fondazione Instituto FIRC di Oncologia Molecolare, Milan, Italy
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Benedetta Pozzi
- Fondazione Instituto FIRC di Oncologia Molecolare, Milan, Italy
| | - Jan Rozman
- German Mouse Clinic, Helmholtz Zentrum München, Munich/Neuherberg, Germany
- Molecular Nutritional Medicine, Technische Universität München, Freising-Weihenstephan, Germany
| | - Ralf Elvert
- German Mouse Clinic, Helmholtz Zentrum München, Munich/Neuherberg, Germany
| | - Nicole Ehrhardt
- German Mouse Clinic, Helmholtz Zentrum München, Munich/Neuherberg, Germany
| | - Birgit Rathkolb
- German Mouse Clinic, Helmholtz Zentrum München, Munich/Neuherberg, Germany
- Institute of Molecular Animal Breeding and Biotechnology, Ludwig Maximilians Universität München, Munich, Germany
| | - Corinna Moerth
- German Mouse Clinic, Helmholtz Zentrum München, Munich/Neuherberg, Germany
- Institute of Molecular Animal Breeding and Biotechnology, Ludwig Maximilians Universität München, Munich, Germany
| | - Marion Horsch
- German Mouse Clinic, Helmholtz Zentrum München, Munich/Neuherberg, Germany
| | - Helmut Fuchs
- German Mouse Clinic, Helmholtz Zentrum München, Munich/Neuherberg, Germany
| | | | - Johannes Beckers
- German Mouse Clinic, Helmholtz Zentrum München, Munich/Neuherberg, Germany
- Lehrstuhl für Experimentelle Genetik, Technische Universität München, Freising-Weihenstephan, Germany
| | - Martin Klingenspor
- Molecular Nutritional Medicine, Technische Universität München, Freising-Weihenstephan, Germany
| | - Eckhard Wolf
- Institute of Molecular Animal Breeding and Biotechnology, Ludwig Maximilians Universität München, Munich, Germany
| | - Martin Hrabé de Angelis
- German Mouse Clinic, Helmholtz Zentrum München, Munich/Neuherberg, Germany
- Lehrstuhl für Experimentelle Genetik, Technische Universität München, Freising-Weihenstephan, Germany
| | - Eugenio Scanziani
- Facoltà di Medicina Veterinaria, Università degli Studi di Milano, Milan, Italy
| | - Carlo Tacchetti
- Fondazione Instituto FIRC di Oncologia Molecolare, Milan, Italy
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Giorgio Scita
- Fondazione Instituto FIRC di Oncologia Molecolare, Milan, Italy
- Dipartimento di Medicina, Chirurgia ed Odontoiatria, Universita' degli Studi di Milano, Milan, Italy
| | - Pier Paolo Di Fiore
- Fondazione Instituto FIRC di Oncologia Molecolare, Milan, Italy
- Dipartimento di Medicina, Chirurgia ed Odontoiatria, Universita' degli Studi di Milano, Milan, Italy
- Istituto Europeo di Oncologia, Milan, Italy
- * E-mail: (PPDF); (NO)
| | - Nina Offenhäuser
- Fondazione Instituto FIRC di Oncologia Molecolare, Milan, Italy
- * E-mail: (PPDF); (NO)
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5
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Offenhäuser N, Castelletti D, Mapelli L, Soppo BE, Regondi MC, Rossi P, D'Angelo E, Frassoni C, Amadeo A, Tocchetti A, Pozzi B, Disanza A, Guarnieri D, Betsholtz C, Scita G, Heberlein U, Di Fiore PP. Increased ethanol resistance and consumption in Eps8 knockout mice correlates with altered actin dynamics. Cell 2006; 127:213-26. [PMID: 17018287 DOI: 10.1016/j.cell.2006.09.011] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2006] [Revised: 07/30/2006] [Accepted: 09/08/2006] [Indexed: 01/18/2023]
Abstract
Dynamic modulation of the actin cytoskeleton is critical for synaptic plasticity, abnormalities of which are thought to contribute to mental illness and addiction. Here we report that mice lacking Eps8, a regulator of actin dynamics, are resistant to some acute intoxicating effects of ethanol and show increased ethanol consumption. In the brain, the N-methyl-D-aspartate (NMDA) receptor is a major target of ethanol. We show that Eps8 is localized to postsynaptic structures and is part of the NMDA receptor complex. Moreover, in Eps8 null mice, NMDA receptor currents and their sensitivity to inhibition by ethanol are abnormal. In addition, Eps8 null neurons are resistant to the actin-remodeling activities of NMDA and ethanol. We propose that proper regulation of the actin cytoskeleton is a key determinant of cellular and behavioral responses to ethanol.
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Affiliation(s)
- Nina Offenhäuser
- Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milan, Italy.
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6
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Ceci M, Gaviraghi C, Gorrini C, Sala LA, Offenhäuser N, Marchisio PC, Biffo S. Release of eIF6 (p27BBP) from the 60S subunit allows 80S ribosome assembly. Nature 2003; 426:579-84. [PMID: 14654845 DOI: 10.1038/nature02160] [Citation(s) in RCA: 319] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2003] [Accepted: 10/10/2003] [Indexed: 12/13/2022]
Abstract
The assembly of 80S ribosomes requires joining of the 40S and 60S subunits, which is triggered by the formation of an initiation complex on the 40S subunit. This event is rate-limiting for translation, and depends on external stimuli and the status of the cell. Here we show that 60S subunits are activated by release of eIF6 (also termed p27BBP). In the cytoplasm, eIF6 is bound to free 60S but not to 80S. Furthermore, eIF6 interacts in the cytoplasm with RACK1, a receptor for activated protein kinase C (PKC). RACK1 is a major component of translating ribosomes, which harbour significant amounts of PKC. Loading 60S subunits with eIF6 caused a dose-dependent translational block and impairment of 80S formation, which were reversed by expression of RACK1 and stimulation of PKC in vivo and in vitro. PKC stimulation led to eIF6 phosphorylation, and mutation of a serine residue in the carboxy terminus of eIF6 impaired RACK1/PKC-mediated translational rescue. We propose that eIF6 release regulates subunit joining, and that RACK1 provides a physical and functional link between PKC signalling and ribosome activation.
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Affiliation(s)
- Marcello Ceci
- Molecular Histology Unit, DIBIT-HSR, 20132 Milano, Italy
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7
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Offenhäuser N, Borgonovo A, Disanza A, Romano P, Ponzanelli I, Iannolo G, Di Fiore PP, Scita G. The eps8 family of proteins links growth factor stimulation to actin reorganization generating functional redundancy in the Ras/Rac pathway. Mol Biol Cell 2003; 15:91-8. [PMID: 14565974 PMCID: PMC307530 DOI: 10.1091/mbc.e03-06-0427] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Sos-1, a guanine nucleotide exchange factor (GEF), eps8 and Abi1, two signaling proteins, and the lipid kinase phosphoinositide 3-kinase (PI3-K), assemble in a multimolecular complex required for Rac activation leading to actin cytoskeletal remodeling. Consistently, eps8 -/- fibroblasts fail to form membrane ruffles in response to growth factor stimulation. Surprisingly, eps8 null mice are healthy, fertile, and display no overt phenotype, suggesting the existence of functional redundancy within this pathway. Here, we describe the identification and characterization of a family of eps8-related proteins, comprising three novel gene products, named eps8L1, eps8L2, and eps8L3. Eps8Ls display collinear topology and 27-42% identity to eps8. Similarly to eps8, eps8Ls interact with Abi1 and Sos-1; however, only eps8L1 and eps8L2 activate the Rac-GEF activity of Sos-1, and bind to actin in vivo. Consistently, eps8L1 and eps8L2, but not eps8L3, localize to PDGF-induced, F-actin-rich ruffles and restore receptor tyrosine kinase (RTK)-mediated actin remodeling when expressed in eps8 -/- fibroblasts. Thus, the eps8Ls define a novel family of proteins responsible for functional redundancy in the RTK-activated signaling pathway leading to actin remodeling. Finally, the patterns of expression of eps8 and eps8L2 in mice are remarkably overlapping, thus providing a likely explanation for the lack of overt phenotype in eps8 null mice.
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8
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Abstract
p27(BBP)/eIF6 is an evolutionarily conserved protein necessary for ribosome biogenesis which was cloned in mammals for its ability to bind the cytodomain of beta 4 integrin. In cultured cells, a conspicuous fraction of p27(BBP)/eIF6 is associated with the intermediate filaments/nuclear matrix (IF/NM) cytoskeleton. The mechanism of this association is not known. Here we show that in epidermis p27(BBP)/eIF6 is naturally associated with IF/NM. To analyze the intrinsic capability of p27(BBP)/eIF6 to generate cytoskeletal networks, the properties of the pure, recombinant, untagged protein were studied. Recombinant p27(BBP)/eIF6 binds beta 4 integrin. Upon dialysis against IF buffer, p27(BBP)/eIF6 forms polymers which, strikingly, have a morphology identical to NM filaments. Cross-linking experiments suggested that polymerization is favored by the formation of disulphide bridges. These data suggest that p27(BBP)/eIF6 is associated with the cytoskeleton, and contributes to formation of NM filaments. These findings help to settle the controversy on nuclear matrix.
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Affiliation(s)
- Marcello Ceci
- University Vita-Salute San Raffaele School of Medicine, Milan, Italy
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9
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Abstract
Truncated trkB.T1 is a splice variant of the neurotrophin receptor trkB. In spite of its abundance, and ability to bind and internalize BDNF, it is not clear whether it can transmit BDNF signaling. We tested this hypothesis by searching for proteins binding the evolutionarily conserved cyto-domain of trkB.T1, and by studying BDNF-induced changes of gene expression through DNA microarrays. Cells bearing trkB.T1 receptors presented morphological changes. However, no cytoplasmic interactors of trkB.T1 were found. In addition, BDNF-dependent modulation of gene expression was detected in cells bearing trkB.TK but not trkB.T1 receptors. These results suggest that the main function of trkB.T1 is to regulate local availability of neurotrophins and that it is unable to sense changes in BDNF availability.
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MESH Headings
- 3T3 Cells
- Alternative Splicing/drug effects
- Alternative Splicing/physiology
- Animals
- Brain-Derived Neurotrophic Factor/pharmacology
- Cell Size/drug effects
- Cell Size/physiology
- Endocytosis/drug effects
- Endocytosis/physiology
- Gene Expression/drug effects
- Gene Expression/physiology
- Genes/drug effects
- Genes/physiology
- Mice
- Nervous System/drug effects
- Nervous System/growth & development
- Nervous System/metabolism
- Nervous System Diseases/drug therapy
- Neuronal Plasticity/drug effects
- Neuronal Plasticity/physiology
- Neurons/drug effects
- Neurons/metabolism
- Neuroprotective Agents/pharmacology
- Protein Binding/drug effects
- Protein Binding/physiology
- Protein Isoforms/drug effects
- Protein Isoforms/genetics
- Protein Isoforms/metabolism
- Protein Structure, Tertiary/drug effects
- Protein Structure, Tertiary/physiology
- RNA, Messenger/drug effects
- RNA, Messenger/metabolism
- Receptor, trkB/drug effects
- Receptor, trkB/genetics
- Receptor, trkB/metabolism
- Receptors, Cell Surface/drug effects
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Signal Transduction/drug effects
- Signal Transduction/physiology
- Transcription, Genetic/drug effects
- Transcription, Genetic/physiology
- Transduction, Genetic
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10
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Dragon S, Offenhäuser N, Baumann R. cAMP and in vivo hypoxia induce tob, ifr1, and fos expression in erythroid cells of the chick embryo. Am J Physiol Regul Integr Comp Physiol 2002; 282:R1219-26. [PMID: 11893628 DOI: 10.1152/ajpregu.00507.2001] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During avian embryonic development, terminal erythroid differentiation occurs in the circulation. Some of the key events, such as the induction of erythroid 2,3-bisphosphoglycerate (2,3-BPG), carbonic anhydrase (CAII), and pyrimidine 5'-nucleotidase (P5N) synthesis are oxygen dependent (Baumann R, Haller EA, Schöning U, and Weber M, Dev Biol 116: 548-551, 1986; Dragon S and Baumann R, Am J Physiol Regulatory Integrative Comp Physiol 280: R870-R878, 2001; Dragon S, Carey C, Martin K, and Baumann R, J Exp Biol 202: 2787-2795, 1999; Dragon S, Glombitza S, Götz R, and Baumann R, Am J Physiol Regulatory Integrative Comp Physiol 271: R982-R989, 1996; Dragon S, Hille R, Götz R, and Baumann R, Blood 91: 3052-3058, 1998; Million D, Zillner P, and Baumann R, Am J Physiol Regulatory Integrative Comp Physiol 261: R1188-R1196, 1991) in an indirect way: hypoxia stimulates the release of norepinephrine (NE)/adenosine into the circulation (Dragon et al., J Exp Biol 202: 2787-2795, 1999; Dragon et al., Am J Physiol Regulatory Integrative Comp Physiol 271: R982-R989, 1996). This leads via erythroid beta-adrenergic/adenosine A(2) receptor activation to a cAMP signal inducing several proteins in a transcription-dependent manner (Dragon et al., Am J Physiol Regulatory Integrative Comp Physiol 271: R982-R989, 1996; Dragon et al., Blood 91: 3052-3058, 1998; Glombitza S, Dragon S, Berghammer M, Pannermayr M, and Baumann R, Am J Physiol Regulatory Integrative Comp Physiol 271: R973-R981, 1996). To understand how the cAMP-dependent processes are initiated, we screened an erythroid cDNA library for cAMP-regulated genes. We detected three genes that were strongly upregulated (>5-fold) by cAMP in definitive and primitive red blood cells. They are homologous to the mammalian Tob, Ifr1, and Fos proteins. In addition, the genes are induced in the intact embryo during short-term hypoxia. Because the genes are regulators of proliferation and differentiation in other cell types, we suggest that cAMP might promote general differentiating processes in erythroid cells, thereby allowing adaptive modulation of the latest steps of erythroid differentiation during developmental hypoxia.
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Affiliation(s)
- Stefanie Dragon
- Physiologisches Institut, Universität Regensburg, 93053 Regensburg, Germany.
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11
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Abstract
Eps15 and Eps15R are related tyrosine kinase substrates, which have been implicated in endocytosis and synaptic vesicle recycling. Through the protein:protein interaction abilities of their EH domains, they establish a complex network of interactions with several proteins, including Numb, a protein necessary for neuronal cell fate specification. We analyzed the expression of Eps15 and Eps15R during murine development, at the time of active neurogenesis. The most striking difference was at the level of subcellular localization, with Eps15 present in the cytosol and on the plasma membrane, while Eps15R exhibited mainly a nuclear localization. Interesting topographical differences also emerged. In the 12.5 days post coitum neuroepithelium, Eps15 was expressed in the ventricular zone, which contains proliferating neuroblasts, whereas Eps15R was found only in postmitotic neurons. Conversely, both proteins were expressed in sensory and cranial ganglia. At later times, the expression of Eps15 and Eps15R was widely maintained in neuronal structures. In other tissues, Eps15 was first seen in the liver primordium and at low levels in choroid plexus, lung, kidney and intestine; later on the expression was maintained at high levels in epithelia. Nuclear staining of Eps15R was present in kidney, intestine, lung and liver, as well as in heart and pancreas.
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Affiliation(s)
- N Offenhäuser
- Department of Experimental Oncology, European Institute of Oncology, Via Ripamonti 435, 20141, Milan, Italy
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Carter BD, Kaltschmidt C, Kaltschmidt B, Offenhäuser N, Böhm-Matthaei R, Baeuerle PA, Barde YA. Selective activation of NF-kappa B by nerve growth factor through the neurotrophin receptor p75. Science 1996; 272:542-5. [PMID: 8614802 DOI: 10.1126/science.272.5261.542] [Citation(s) in RCA: 507] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3) selectively bind to distinct members of the Trk family of tyrosine kinase receptors, but all three bind with similar affinities to the neurotrophin receptor p75 (p75NTR). The biological significance of neurotrophin binding to p75NTR in cells that also express Trk receptors has been difficult to ascertain. In the absence of TrkA, NGF binding to p75NGR activated the transcription factor nuclear factor kappa B (NF-kappa B) in rat Schwann cells. This activation was not observed in Schwann cells isolated from mice that lacked p75NTR. The effect was selective for NGF; NF-kappa B was not activated by BDNF or NT-3.
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Affiliation(s)
- B D Carter
- Department of Neurobiochemistry, Max-Planck Institute for Psychiatry, Martinsried, Germany
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13
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Biffo S, Offenhäuser N, Carter BD, Barde YA. Selective binding and internalisation by truncated receptors restrict the availability of BDNF during development. Development 1995; 121:2461-70. [PMID: 7671810 DOI: 10.1242/dev.121.8.2461] [Citation(s) in RCA: 166] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The tyrosine kinase receptor trkB is thought to mediate the biological actions of brain-derived neurotrophic factor. This receptor is expressed by a large variety of neurons during development. Truncated trkB molecules lacking the tyrosine kinase domain have also been described, but their functions remain elusive. In order to gain insight into their role, we studied the pattern of expression and properties of these truncated receptors in the chick embryo. mRNA coding for truncated trkB was detected already early during neurogenesis and in situ hybridisation experiments indicated that the expression was in non-neuronal cells, as previously observed in the brain of adult rodents. Ependymal and leptomeningeal cells expressing high levels of truncated trkB were found to completely surround the developing brain and the spinal cord throughout development. In the otic vesicle, mesenchymal cells expressing truncated trkB surround cells producing brain-derived neurotrophic factor, as well as neurons expressing trkB with its tyrosine kinase domain. Non-neuronal cells were found not to express trkB mRNA coding for the tyrosine kinase domain. Studies with radioiodinated brain-derived neurotrophic factor performed on frozen sections of the chick embryo revealed that non-neuronal cells expressing truncated trkB bind brain-derived neurotrophic factor with high affinity and selectivity. In addition, experiments with dissociated leptomeningeal cells revealed that binding is rapidly followed by selective internalisation of the ligand. These results suggest that truncated trkB molecules form an efficient and selective barrier preventing the diffusion of brain-derived neurotrophic factor and eliminating it by internalisation.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- S Biffo
- Max-Planck Institute for Psychiatry, Department of Neurobiochemistry, Planegg-Martinsried, Germany
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14
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Abstract
In order to gain insight into potential roles of neurotrophins in Schwann cell biology, the expression of neurotrophin receptors of the trk gene family was investigated in rat sciatic nerve development. This analysis revealed differential regulation of truncated and full-length receptors. TrkA was undetectable even when analysed with a sensitive reverse transcriptase-polymerase chain reaction (RT-PCR) method. TrkB was present at the mRNA as well as protein level only in its truncated form. Surprisingly, multiple isoforms of trkC, including full-length forms, were detected in early postnatal nerve. Specific antibodies detected truncated and full-length trkC proteins in Western blotting, and RT-PCR revealed the presence of two full-length isoforms, one of them containing the 14 amino acid kinase insert. In situ hybridisation localized the expression of trkC to a subpopulation of Schwann cells. TrkC receptors are expressed already in nerves from day-16 embryos. In contrast to early postnatal stages, full-length trkC receptors are no longer expressed in adult nerves, which, however, maintain expression of truncated trkC transcripts. The presence of trkC kinases in peripheral nerve suggests a role for neurotrophin-3, the only known trkC ligand, in peripheral nerve development.
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Affiliation(s)
- N Offenhäuser
- Max Planck Institute for Psychiatry, Martinsried, FRG
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