1
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Richardson DS, Spehar JM, Han DT, Chakravarthy PA, Sizemore ST. The RAL Enigma: Distinct Roles of RALA and RALB in Cancer. Cells 2022; 11:cells11101645. [PMID: 35626682 PMCID: PMC9139244 DOI: 10.3390/cells11101645] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [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: 03/24/2022] [Revised: 04/29/2022] [Accepted: 05/05/2022] [Indexed: 11/16/2022] Open
Abstract
RALA and RALB are highly homologous small G proteins belonging to the RAS superfamily. Like other small GTPases, the RALs are molecular switches that can be toggled between inactive GDP-bound and active GTP-bound states to regulate diverse and critical cellular functions such as vesicle trafficking, filopodia formation, mitochondrial fission, and cytokinesis. The RAL paralogs are activated and inactivated by a shared set of guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs) and utilize similar sets of downstream effectors. In addition to their important roles in normal cell biology, the RALs are known to be critical mediators of cancer cell survival, invasion, migration, and metastasis. However, despite their substantial similarities, the RALs often display striking functional disparities in cancer. RALA and RALB can have redundant, unique, or even antagonistic functions depending on cancer type. The molecular basis for these discrepancies remains an important unanswered question in the field of cancer biology. In this review we examine the functions of the RAL paralogs in normal cellular physiology and cancer biology with special consideration provided to situations where the roles of RALA and RALB are non-redundant.
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2
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Hussain SS, Tran TM, Ware TB, Luse MA, Prevost CT, Ferguson AN, Kashatus JA, Hsu KL, Kashatus DF. RalA and PLD1 promote lipid droplet growth in response to nutrient withdrawal. Cell Rep 2021; 36:109451. [PMID: 34320341 PMCID: PMC8344381 DOI: 10.1016/j.celrep.2021.109451] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 06/04/2021] [Accepted: 07/02/2021] [Indexed: 01/22/2023] Open
Abstract
Lipid droplets (LDs) are dynamic organelles that undergo dynamic changes in response to changing cellular conditions. During nutrient depletion, LD numbers increase to protect cells against toxic fatty acids generated through autophagy and provide fuel for beta-oxidation. However, the precise mechanisms through which these changes are regulated have remained unclear. Here, we show that the small GTPase RalA acts downstream of autophagy to directly facilitate LD growth during nutrient depletion. Mechanistically, RalA performs this function through phospholipase D1 (PLD1), an enzyme that converts phosphatidylcholine (PC) to phosphatidic acid (PA) and that is recruited to lysosomes during nutrient stress in a RalA-dependent fashion. RalA inhibition prevents recruitment of the LD-associated protein perilipin 3, which is required for LD growth. Our data support a model in which RalA recruits PLD1 to lysosomes during nutrient deprivation to promote the localized production of PA and the recruitment of perilipin 3 to expanding LDs.
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Affiliation(s)
- Syed S Hussain
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Tuyet-Minh Tran
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Timothy B Ware
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA
| | - Melissa A Luse
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Christopher T Prevost
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Ashley N Ferguson
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Jennifer A Kashatus
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Ku-Lung Hsu
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA; University of Virginia Cancer Center, University of Virginia Health System, Charlottesville, VA 22903, USA
| | - David F Kashatus
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia Health System, Charlottesville, VA 22908, USA; University of Virginia Cancer Center, University of Virginia Health System, Charlottesville, VA 22903, USA.
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3
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Seibert M, Kurrle N, Schnütgen F, Serve H. Amino acid sensory complex proteins in mTORC1 and macroautophagy regulation. Matrix Biol 2021; 100-101:65-83. [DOI: 10.1016/j.matbio.2021.01.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 01/02/2021] [Accepted: 01/02/2021] [Indexed: 12/15/2022]
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4
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Ghoroghi S, Mary B, Larnicol A, Asokan N, Klein A, Osmani N, Busnelli I, Delalande F, Paul N, Halary S, Gros F, Fouillen L, Haeberle AM, Royer C, Spiegelhalter C, André-Grégoire G, Mittelheisser V, Detappe A, Murphy K, Timpson P, Carapito R, Blot-Chabaud M, Gavard J, Carapito C, Vitale N, Lefebvre O, Goetz JG, Hyenne V. Ral GTPases promote breast cancer metastasis by controlling biogenesis and organ targeting of exosomes. eLife 2021; 10:61539. [PMID: 33404012 PMCID: PMC7822591 DOI: 10.7554/elife.61539] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 01/05/2021] [Indexed: 12/12/2022] Open
Abstract
Cancer extracellular vesicles (EVs) shuttle at distance and fertilize pre-metastatic niches facilitating subsequent seeding by tumor cells. However, the link between EV secretion mechanisms and their capacity to form pre-metastatic niches remains obscure. Using mouse models, we show that GTPases of the Ral family control, through the phospholipase D1, multi-vesicular bodies homeostasis and tune the biogenesis and secretion of pro-metastatic EVs. Importantly, EVs from RalA or RalB depleted cells have limited organotropic capacities in vivoand are less efficient in promoting metastasis. RalA and RalB reduce the EV levels of the adhesion molecule MCAM/CD146, which favors EV-mediated metastasis by allowing EVs targeting to the lungs. Finally, RalA, RalB, and MCAM/CD146, are factors of poor prognosis in breast cancer patients. Altogether, our study identifies RalGTPases as central molecules linking the mechanisms of EVs secretion and cargo loading to their capacity to disseminate and induce pre-metastatic niches in a CD146-dependent manner.
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Affiliation(s)
- Shima Ghoroghi
- INSERM UMR_S1109, Tumor Biomechanics, Strasbourg, France.,Université de Strasbourg, Strasbourg, France.,Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France
| | - Benjamin Mary
- INSERM UMR_S1109, Tumor Biomechanics, Strasbourg, France.,Université de Strasbourg, Strasbourg, France.,Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France
| | - Annabel Larnicol
- INSERM UMR_S1109, Tumor Biomechanics, Strasbourg, France.,Université de Strasbourg, Strasbourg, France.,Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France
| | - Nandini Asokan
- INSERM UMR_S1109, Tumor Biomechanics, Strasbourg, France.,Université de Strasbourg, Strasbourg, France.,Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France
| | - Annick Klein
- INSERM UMR_S1109, Tumor Biomechanics, Strasbourg, France.,Université de Strasbourg, Strasbourg, France.,Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France
| | - Naël Osmani
- INSERM UMR_S1109, Tumor Biomechanics, Strasbourg, France.,Université de Strasbourg, Strasbourg, France.,Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France
| | - Ignacio Busnelli
- INSERM UMR_S1109, Tumor Biomechanics, Strasbourg, France.,Université de Strasbourg, Strasbourg, France.,Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France
| | - François Delalande
- Laboratoire de Spectrométrie de Masse BioOrganique (LSMBO), IPHC UMR 7178, CNRS, Université de Strasbourg, Strasbourg, France
| | - Nicodème Paul
- Université de Strasbourg, Strasbourg, France.,Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France.,INSERM UMR_S1109, Genomax, Strasbourg, France
| | - Sébastien Halary
- CNRS, UMR 7245 MCAM, Muséum National d'Histoire Naturelle de Paris, Paris, France
| | - Frédéric Gros
- INSERM UMR_S1109, Tumor Biomechanics, Strasbourg, France.,Université de Strasbourg, Strasbourg, France.,Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France
| | - Laetitia Fouillen
- Université de Bordeaux, CNRS, Laboratoire de Biogenèse Membranaire, UMR 5200, Villenave d'Ornon, France
| | - Anne-Marie Haeberle
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
| | - Cathy Royer
- Plateforme Imagerie In Vitro, CNRS UPS 3156, Strasbourg, France
| | - Coralie Spiegelhalter
- IGBMC Imaging Center CNRS (UMR7104)/ INSERM (U1258)/ Université de Strasbourg, Illkirch, France
| | - Gwennan André-Grégoire
- Team SOAP, CRCINA, INSERM, CNRS, Université de Nantes, Université d'Angers, Nantes, France.,Integrated Center for Oncology, ICO, St-Herblain, France
| | - Vincent Mittelheisser
- INSERM UMR_S1109, Tumor Biomechanics, Strasbourg, France.,Université de Strasbourg, Strasbourg, France.,Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France.,Nanotranslational laboratory, Institut de Cancérologie Strasbourg Europe, Strasbourg, France
| | - Alexandre Detappe
- Nanotranslational laboratory, Institut de Cancérologie Strasbourg Europe, Strasbourg, France.,Équipe de synthèse pour l'analyse (SynPA), Institut Pluridisciplinaire Hubert Curien (IPHC), UMR7178, CNRS/Université de Strasbourg, Strasbourg, France
| | - Kendelle Murphy
- Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney, Australia.,The Kinghorn Cancer Centre, Garvan Institute of Medical Research, Sydney, Australia
| | - Paul Timpson
- Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney, Australia.,The Kinghorn Cancer Centre, Garvan Institute of Medical Research, Sydney, Australia
| | - Raphaël Carapito
- Université de Strasbourg, Strasbourg, France.,Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France.,INSERM UMR_S1109, Genomax, Strasbourg, France
| | | | - Julie Gavard
- Team SOAP, CRCINA, INSERM, CNRS, Université de Nantes, Université d'Angers, Nantes, France.,Integrated Center for Oncology, ICO, St-Herblain, France
| | - Christine Carapito
- Laboratoire de Spectrométrie de Masse BioOrganique (LSMBO), IPHC UMR 7178, CNRS, Université de Strasbourg, Strasbourg, France
| | - Nicolas Vitale
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
| | - Olivier Lefebvre
- INSERM UMR_S1109, Tumor Biomechanics, Strasbourg, France.,Université de Strasbourg, Strasbourg, France.,Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France
| | - Jacky G Goetz
- INSERM UMR_S1109, Tumor Biomechanics, Strasbourg, France.,Université de Strasbourg, Strasbourg, France.,Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France
| | - Vincent Hyenne
- INSERM UMR_S1109, Tumor Biomechanics, Strasbourg, France.,Université de Strasbourg, Strasbourg, France.,Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France.,CNRS SNC5055, Strasbourg, France
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5
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Abstract
The RAL proteins RALA and RALB belong to the superfamily of small RAS-like GTPases (guanosine triphosphatases). RAL GTPases function as molecular switches in cells by cycling through GDP- and GTP-bound states, a process which is regulated by several guanine exchange factors (GEFs) and two heterodimeric GTPase activating proteins (GAPs). Since their discovery in the 1980s, RALA and RALB have been established to exert isoform-specific functions in central cellular processes such as exocytosis, endocytosis, actin organization and gene expression. Consequently, it is not surprising that an increasing number of physiological functions are discovered to be controlled by RAL, including neuronal plasticity, immune response, and glucose and lipid homeostasis. The critical importance of RAL GTPases for oncogenic RAS-driven cellular transformation and tumorigenesis still attracts most research interest. Here, RAL proteins are key drivers of cell migration, metastasis, anchorage-independent proliferation, and survival. This chapter provides an overview of normal and pathological functions of RAL GTPases and summarizes the current knowledge on the involvement of RAL in human disease as well as current therapeutic targeting strategies. In particular, molecular mechanisms that specifically control RAL activity and RAL effector usage in different scenarios are outlined, putting a spotlight on the complexity of the RAL GTPase signaling network and the emerging theme of RAS-independent regulation and relevance of RAL.
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Affiliation(s)
- Lisa H Apken
- Institute of Molecular Tumor Biology, Faculty of Medicine, University of Münster, Münster, Germany
| | - Andrea Oeckinghaus
- Institute of Molecular Tumor Biology, Faculty of Medicine, University of Münster, Münster, Germany.
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6
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Takahara T, Amemiya Y, Sugiyama R, Maki M, Shibata H. Amino acid-dependent control of mTORC1 signaling: a variety of regulatory modes. J Biomed Sci 2020; 27:87. [PMID: 32799865 PMCID: PMC7429791 DOI: 10.1186/s12929-020-00679-2] [Citation(s) in RCA: 108] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 07/30/2020] [Indexed: 01/10/2023] Open
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) is an essential regulator of cell growth and metabolism through the modulation of protein and lipid synthesis, lysosome biogenesis, and autophagy. The activity of mTORC1 is dynamically regulated by several environmental cues, including amino acid availability, growth factors, energy levels, and stresses, to coordinate cellular status with environmental conditions. Dysregulation of mTORC1 activity is closely associated with various diseases, including diabetes, cancer, and neurodegenerative disorders. The discovery of Rag GTPases has greatly expanded our understanding of the regulation of mTORC1 activity by amino acids, especially leucine and arginine. In addition to Rag GTPases, other factors that also contribute to the modulation of mTORC1 activity have been identified. In this review, we discuss the mechanisms of regulation of mTORC1 activity by particular amino acids.
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Affiliation(s)
- Terunao Takahara
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan.
| | - Yuna Amemiya
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan
| | - Risa Sugiyama
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan
| | - Masatoshi Maki
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan
| | - Hideki Shibata
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan
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7
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Wagner M, Skorobogatko Y, Pode-Shakked B, Powell CM, Alhaddad B, Seibt A, Barel O, Heimer G, Hoffmann C, Demmer LA, Perilla-Young Y, Remke M, Wieczorek D, Navaratnarajah T, Lichtner P, Klee D, Shamseldin HE, Al Mutairi F, Mayatepek E, Strom T, Meitinger T, Alkuraya FS, Anikster Y, Saltiel AR, Distelmaier F. Bi-allelic Variants in RALGAPA1 Cause Profound Neurodevelopmental Disability, Muscular Hypotonia, Infantile Spasms, and Feeding Abnormalities. Am J Hum Genet 2020; 106:246-255. [PMID: 32004447 DOI: 10.1016/j.ajhg.2020.01.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 01/06/2020] [Indexed: 12/30/2022] Open
Abstract
Ral (Ras-like) GTPases play an important role in the control of cell migration and have been implicated in Ras-mediated tumorigenicity. Recently, variants in RALA were also described as a cause of intellectual disability and developmental delay, indicating the relevance of this pathway to neuropediatric diseases. Here, we report the identification of bi-allelic variants in RALGAPA1 (encoding Ral GTPase activating protein catalytic alpha subunit 1) in four unrelated individuals with profound neurodevelopmental disability, muscular hypotonia, feeding abnormalities, recurrent fever episodes, and infantile spasms . Dysplasia of corpus callosum with focal thinning of the posterior part and characteristic facial features appeared to be unifying findings. RalGAPA1 was absent in the fibroblasts derived from two affected individuals suggesting a loss-of-function effect of the RALGAPA1 variants. Consequently, RalA activity was increased in these cell lines, which is in keeping with the idea that RalGAPA1 deficiency causes a constitutive activation of RalA. Additionally, levels of RalGAPB, a scaffolding subunit of the RalGAP complex, were dramatically reduced, indicating a dysfunctional RalGAP complex. Moreover, RalGAPA1 deficiency clearly increased cell-surface levels of lipid raft components in detached fibroblasts, which might indicate that anchorage-dependence of cell growth signaling is disturbed. Our findings indicate that the dysregulation of the RalA pathway has an important impact on neuronal function and brain development. In light of the partially overlapping phenotype between RALA- and RALGAPA1-associated diseases, it appears likely that dysregulation of the RalA signaling pathway leads to a distinct group of genetic syndromes that we suggest could be named RALopathies.
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8
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Abstract
Cancer cells consume glutamine, a nonessential amino acid (NEAA), at exceedingly high rates to fulfill their energetic and biosynthetic requirements for proliferation. Glutamine plays distinct roles from essential amino acids in cell cycle progression and in the activation of mammalian target of rapamycin (mTOR). Furthermore, the need of cancer cells for glutamine can be exploited therapeutically - especially those driven by KRas. In this review we explore several distinct cellular roles for glutamine that contribute to glutamine addiction in KRas-driven cancer cells and discuss opportunities for therapeutic intervention created by glutamine addiction.
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Affiliation(s)
- Elyssa Bernfeld
- Department of Biological Sciences, Hunter College of the City University of New York, New York, NY, USA; Biochemistry PhD Program, The Graduate Center, City University of New York, New York, NY, USA; Current address: Oncology R&D Group, Pfizer Worldwide Research and Development, 401 N. Middletown Road, Pearl River, NY, USA
| | - David A Foster
- Department of Biological Sciences, Hunter College of the City University of New York, New York, NY, USA; Biochemistry PhD Program, The Graduate Center, City University of New York, New York, NY, USA; Department of Pharmacology, Weill Cornell Medicine, New York, NY, USA.
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9
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Bernfeld E, Menon D, Vaghela V, Zerin I, Faruque P, Frias MA, Foster DA. Phospholipase D-dependent mTOR complex 1 (mTORC1) activation by glutamine. J Biol Chem 2018; 293:16390-16401. [PMID: 30194281 DOI: 10.1074/jbc.ra118.004972] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 08/31/2018] [Indexed: 01/06/2023] Open
Abstract
Glutamine is a key nutrient required for sustaining cell proliferation, contributing to nucleotide, protein, and lipid synthesis. The mTOR complex 1 (mTORC1) is a highly conserved protein complex that acts as a sensor of nutrients, relaying signals for the shift from catabolic to anabolic metabolism. Although glutamine plays an important role in mTORC1 activation, the mechanism is not clear. Here we describe a leucine- and Rag-independent mechanism of mTORC1 activation by glutamine that depends on phospholipase D and the production of phosphatidic acid, which is required for the stability and activity of mTORC1. The phospholipase D-dependent activation of mTORC1 by glutamine depended on the GTPases ADP ribosylation factor 1 (Arf1), RalA, and Rheb. Glutamine deprivation could be rescued by α-ketoglutarate, a downstream metabolite of glutamine. This mechanism represents a distinct nutrient input to mTORC1 that is independent of Rag GTPases and leucine.
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Affiliation(s)
- Elyssa Bernfeld
- From the Departments of Biological Sciences and.,the Biochemistry Program and
| | - Deepak Menon
- From the Departments of Biological Sciences and.,the Biochemistry Program and
| | - Vishaldeep Vaghela
- From the Departments of Biological Sciences and.,Biology Program, Graduate Center, City University of New York, New York, New York 10016, and
| | - Ismat Zerin
- Chemistry, Hunter College, City University of New York, New York, New York 10065
| | | | | | - David A Foster
- From the Departments of Biological Sciences and .,the Biochemistry Program and.,Biology Program, Graduate Center, City University of New York, New York, New York 10016, and.,the Department of Pharmacology, Weill Cornell Medicine, New York, New York 10021
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10
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Zhang X, Kim KM. Multifactorial Regulation of G Protein-Coupled Receptor Endocytosis. Biomol Ther (Seoul) 2017; 25:26-43. [PMID: 28035080 PMCID: PMC5207461 DOI: 10.4062/biomolther.2016.186] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 11/21/2016] [Accepted: 11/30/2016] [Indexed: 12/26/2022] Open
Abstract
Endocytosis is a process by which cells absorb extracellular materials via the inward budding of vesicles formed from the plasma membrane. Receptor-mediated endocytosis is a highly selective process where receptors with specific binding sites for extracellular molecules internalize via vesicles. G protein-coupled receptors (GPCRs) are the largest single family of plasma-membrane receptors with more than 1000 family members. But the molecular mechanisms involved in the regulation of GPCRs are believed to be highly conserved. For example, receptor phosphorylation in collaboration with β-arrestins plays major roles in desensitization and endocytosis of most GPCRs. Nevertheless, a number of subsequent studies showed that GPCR regulation, such as that by endocytosis, occurs through various pathways with a multitude of cellular components and processes. This review focused on i) functional interactions between homologous and heterologous pathways, ii) methodologies applied for determining receptor endocytosis, iii) experimental tools to determine specific endocytic routes, iv) roles of small guanosine triphosphate-binding proteins in GPCR endocytosis, and v) role of post-translational modification of the receptors in endocytosis.
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Affiliation(s)
- Xiaohan Zhang
- Pharmacology Laboratory, College of Pharmacy, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Kyeong-Man Kim
- Pharmacology Laboratory, College of Pharmacy, Chonnam National University, Gwangju 61186, Republic of Korea
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11
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Abstract
Extracellular vesicles are novel mediators of cell-cell communication. They are present in all species and involved in physiological and pathological processes. One class of extracellular vesicles, the exosomes, originate from an endosomal compartment, the MultiVesicular Body (MVB), and are released from the cell upon fusion of the MVB with the plasma membrane. Although different molecular mechanisms have been associated with MVB biogenesis and exosome secretion, how they coordinate remains poorly documented. We recently found that the small GTPase Ral contributes to exosome release in nematodes and mammalian tumor cells. More specifically, we found that C. elegans RAL-1 is required for the biogenesis of MVBs, and later for MVB fusion with the plasma membrane. Here, we discuss our results in relationship with other factors involved in extracellular vesicle production such as the ESCRT complex and Phospholipase 1D. We propose models to explain Ral function in exosome secretion, its conservation in animals, and its possible role in tumor progression.
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Affiliation(s)
- Vincent Hyenne
- a Inserm U1109 , MN3T , Strasbourg , France.,b Université de Strasbourg , Strasbourg , France.,c LabEx Medalis , Université de Strasbourg , Strasbourg , France.,d Fédération de Médecine Translationnelle de Strasbourg (FMTS) , Strasbourg , France.,e CNRS SNC5055 , Strasbourg , France
| | - Michel Labouesse
- f Sorbonne Universités , UPMC Univ Paris 06, UMR7622 - CNRS, Institut de Biologie Paris-Seine , Paris , France
| | - Jacky G Goetz
- a Inserm U1109 , MN3T , Strasbourg , France.,b Université de Strasbourg , Strasbourg , France.,c LabEx Medalis , Université de Strasbourg , Strasbourg , France.,d Fédération de Médecine Translationnelle de Strasbourg (FMTS) , Strasbourg , France
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12
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Duan Y, Li J, Zhang Z, Li J, Liu P. Characterization of ADP ribosylation factor 1 gene from Exopalaemon carinicauda and its immune response to pathogens challenge and ammonia-N stress. Fish Shellfish Immunol 2016; 55:123-130. [PMID: 27231192 DOI: 10.1016/j.fsi.2016.05.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 05/20/2016] [Accepted: 05/22/2016] [Indexed: 06/05/2023]
Abstract
ADP ribosylation factors (Arf), as highly conserved small guanosine triphosphate (GTP)-binding proteins, participates in intracellular trafficking and organelle structure. In this study, a full-length cDNA of Arf1 (designated EcArf1) was cloned from Exopalaemon carinicauda by using rapid amplification of cDNA ends (RACE) approaches. The full-length cDNA of EcArf1 was 1428 bp, which contains an open reading frame (ORF) of 549 bp, encoding a 182 amino-acid polypeptide with the predicted molecular weight of 20.69 kDa and estimated isoelectric point was 7.24. Sequence analysis revealed that the conserved Arf protein family signatures were identified in EcArf1. The deduced amino acid sequence of EcArf1 shared high identity (95%-98%) with that of other species and clustered together with Arf1 of other shrimp in the NJ phylogenetic tree, indicating that EcArf1 should be a member of the Arf1 family. Quantitative real-time RT-qPCR analysis indicated that EcArf1 was expressed in hemocytes, hepatopancreas, gills, muscle, ovary, intestine, stomach and heart, and the most abundant level was in hemocytes and gills, which were also the two main target tissues of pathogen infection and environmental stress. After Vibrio parahaemolyticus challenge, EcArf1 transcripts level significantly increased in hemocytes and hepatopancreas at 3 h and 6 h, respectively. The expression of EcArf1 in hemocytes and hepatopancreas significantly up-regulated at 12 h and 6 h respectively, and down-regulated at 72 h and 48 h, respectively. EcArf1 expression in hepatopancreas and gills both significantly increased at 6 h and decreased at 24 h under ammonia-N stress. The results suggested that EcArf1 might be involved in immune responses to pathogens (V. parahaemolyticus and WSSV) challenge and ammonia-N stress in E. carinicauda.
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Affiliation(s)
- Yafei Duan
- Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, PR China
| | - Jian Li
- Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, PR China; Function Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, PR China
| | - Zhe Zhang
- Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, PR China
| | - Jitao Li
- Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, PR China; Function Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, PR China
| | - Ping Liu
- Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, PR China; Function Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, PR China.
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13
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Pawar A, Meier JA, Dasgupta A, Diwanji N, Deshpande N, Saxena K, Buwa N, Inchanalkar S, Schwartz MA, Balasubramanian N. Ral-Arf6 crosstalk regulates Ral dependent exocyst trafficking and anchorage independent growth signalling. Cell Signal 2016; 28:1225-1236. [PMID: 27269287 PMCID: PMC4973806 DOI: 10.1016/j.cellsig.2016.05.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 05/30/2016] [Accepted: 05/31/2016] [Indexed: 12/01/2022]
Abstract
Integrin dependent regulation of growth factor signalling confers anchorage dependence that is deregulated in cancers. Downstream of integrins and oncogenic Ras the small GTPase Ral is a vital mediator of adhesion dependent trafficking and signalling. This study identifies a novel regulatory crosstalk between Ral and Arf6 that controls Ral function in cells. In re-adherent mouse fibroblasts (MEFs) integrin dependent activation of RalA drives Arf6 activation. Independent of adhesion constitutively active RalA and RalB could both however activate Arf6. This is further conserved in oncogenic H-Ras containing bladder cancer T24 cells, which express anchorage independent active Ral that supports Arf6 activation. Arf6 mediates active Ral-exocyst dependent delivery of raft microdomains to the plasma membrane that supports anchorage independent growth signalling. Accordingly in T24 cells the RalB-Arf6 crosstalk is seen to preferentially regulate anchorage independent Erk signalling. Active Ral we further find uses a Ral-RalBP1-ARNO-Arf6 pathway to mediate Arf6 activation. This study hence identifies Arf6, through this regulatory crosstalk, to be a key downstream mediator of Ral isoform function along adhesion dependent pathways in normal and cancer cells. Ral mediates Arf6 activation downstream of integrins and oncogenic Ras. Arf6 mediates Ral-exocyst dependent delivery of raft microdomains. Active Ral supports anchorage independent Arf6 activation in bladder cancer T24 cells. Ral-Arf6 crosstalk in T24 cells regulates anchorage independent Erk signalling. A Ral-RalBP1-ARNO-Arf6 pathway mediates the Ral-Arf6 crosstalk.
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Affiliation(s)
- Archana Pawar
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411 008, Maharashtra, India
| | - Jeremy A Meier
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, United States
| | - Anwesha Dasgupta
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411 008, Maharashtra, India
| | - Neha Diwanji
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411 008, Maharashtra, India
| | - Neha Deshpande
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411 008, Maharashtra, India
| | - Kritika Saxena
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411 008, Maharashtra, India
| | - Natasha Buwa
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411 008, Maharashtra, India
| | - Siddhi Inchanalkar
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411 008, Maharashtra, India
| | - Martin Alexander Schwartz
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, United States; Yale Cardiovascular Research Center, 300 George Street, 7th Floor, New Haven, CT 06511, United States
| | - Nagaraj Balasubramanian
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411 008, Maharashtra, India.
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14
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Abstract
We report the identification of Ima, a novel Drosophila MAGUK-like protein, which contains two WW and four PDZ protein interaction domains and interacts with the small GTPase dRal in the yeast two-hybrid system and pull-down assays. The gene is expressed in distinct spatiotemporal patterns throughout embryonic development. Overexpression of Ima interferes with normal Drosophila development, indicating that the gene functions in a tissue specific manner.
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Affiliation(s)
- Mathias Beller
- Abteilung Molekulare Entwicklungsbiologie, Max-Planck-Institut für biophysikalische Chemie, Am Fassberg, 37077 Göttingen, Germany
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15
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Hyenne V, Apaydin A, Rodriguez D, Spiegelhalter C, Hoff-Yoessle S, Diem M, Tak S, Lefebvre O, Schwab Y, Goetz JG, Labouesse M. RAL-1 controls multivesicular body biogenesis and exosome secretion. J Cell Biol 2016; 211:27-37. [PMID: 26459596 PMCID: PMC4602040 DOI: 10.1083/jcb.201504136] [Citation(s) in RCA: 160] [Impact Index Per Article: 20.0] [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] [Indexed: 12/13/2022] Open
Abstract
Exosomes are secreted vesicles arising from the fusion of multivesicular bodies (MVBs) with the plasma membrane. Despite their importance in various processes, the molecular mechanisms controlling their formation and release remain unclear. Using nematodes and mammary tumor cells, we show that Ral GTPases are involved in exosome biogenesis. In Caenorhabditis elegans, RAL-1 localizes at the surface of secretory MVBs. A quantitative electron microscopy analysis of RAL-1-deficient animals revealed that RAL-1 is involved in both MVB formation and their fusion with the plasma membrane. These functions do not involve the exocyst complex, a common Ral guanosine triphosphatase (GTPase) effector. Furthermore, we show that the target membrane SNARE protein SYX-5 colocalizes with a constitutively active form of RAL-1 at the plasma membrane, and MVBs accumulate under the plasma membrane when SYX-5 is absent. In mammals, RalA and RalB are both required for the secretion of exosome-like vesicles in cultured cells. Therefore, Ral GTPases represent new regulators of MVB formation and exosome release.
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Affiliation(s)
- Vincent Hyenne
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Development and Stem Cells Program, Centre National de la Recherche Scientifique (UMR7104), Institut National de la Santé et de la Recherche Médicale (U964), Université de Strasbourg, 67400 Illkirch, France MN3T, Institut National de la Santé et de la Recherche Médicale (U1109), LabEx Medalis, Université de Strasbourg, 67200 Strasbourg, France Fédération de Médecine Translationnelle de Strasbourg, 67200 Strasbourg, France
| | - Ahmet Apaydin
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Development and Stem Cells Program, Centre National de la Recherche Scientifique (UMR7104), Institut National de la Santé et de la Recherche Médicale (U964), Université de Strasbourg, 67400 Illkirch, France
| | - David Rodriguez
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Development and Stem Cells Program, Centre National de la Recherche Scientifique (UMR7104), Institut National de la Santé et de la Recherche Médicale (U964), Université de Strasbourg, 67400 Illkirch, France
| | - Coralie Spiegelhalter
- Institut de Génétique et de Biologie Moléculaire et Cellulaire Imaging Center, Centre National de la Recherche Scientifique (UMR7104), Institut National de la Santé et de la Recherche Médicale (U964), Université de Strasbourg, 67400 Illkirch, France
| | - Sarah Hoff-Yoessle
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Development and Stem Cells Program, Centre National de la Recherche Scientifique (UMR7104), Institut National de la Santé et de la Recherche Médicale (U964), Université de Strasbourg, 67400 Illkirch, France
| | - Maxime Diem
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Development and Stem Cells Program, Centre National de la Recherche Scientifique (UMR7104), Institut National de la Santé et de la Recherche Médicale (U964), Université de Strasbourg, 67400 Illkirch, France
| | - Saurabh Tak
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Development and Stem Cells Program, Centre National de la Recherche Scientifique (UMR7104), Institut National de la Santé et de la Recherche Médicale (U964), Université de Strasbourg, 67400 Illkirch, France
| | - Olivier Lefebvre
- MN3T, Institut National de la Santé et de la Recherche Médicale (U1109), LabEx Medalis, Université de Strasbourg, 67200 Strasbourg, France Fédération de Médecine Translationnelle de Strasbourg, 67200 Strasbourg, France
| | - Yannick Schwab
- Institut de Génétique et de Biologie Moléculaire et Cellulaire Imaging Center, Centre National de la Recherche Scientifique (UMR7104), Institut National de la Santé et de la Recherche Médicale (U964), Université de Strasbourg, 67400 Illkirch, France Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Jacky G Goetz
- MN3T, Institut National de la Santé et de la Recherche Médicale (U1109), LabEx Medalis, Université de Strasbourg, 67200 Strasbourg, France Fédération de Médecine Translationnelle de Strasbourg, 67200 Strasbourg, France
| | - Michel Labouesse
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Development and Stem Cells Program, Centre National de la Recherche Scientifique (UMR7104), Institut National de la Santé et de la Recherche Médicale (U964), Université de Strasbourg, 67400 Illkirch, France Institut de Biologie Paris (UMR7622), UPMC, 75005 Paris, France
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16
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Shirakawa R, Horiuchi H. Ral GTPases: crucial mediators of exocytosis and tumourigenesis. J Biochem 2015; 157:285-99. [DOI: 10.1093/jb/mvv029] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 02/07/2015] [Indexed: 11/12/2022] Open
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17
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Luo K, Luo D, Liu H. Determination of Metabolites in the Cerebellum of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin Exposed Mice by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry. ANAL LETT 2014. [DOI: 10.1080/00032719.2014.952373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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18
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Gentry LR, Martin TD, Reiner DJ, Der CJ. Ral small GTPase signaling and oncogenesis: More than just 15minutes of fame. Biochim Biophys Acta 2014; 1843:2976-2988. [PMID: 25219551 DOI: 10.1016/j.bbamcr.2014.09.004] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 09/03/2014] [Accepted: 09/04/2014] [Indexed: 01/26/2023]
Abstract
Since their discovery in 1986, Ral (Ras-like) GTPases have emerged as critical regulators of diverse cellular functions. Ral-selective guanine nucleotide exchange factors (RalGEFs) function as downstream effectors of the Ras oncoprotein, and the RalGEF-Ral signaling network comprises the third best characterized effector of Ras-dependent human oncogenesis. Because of this, Ral GTPases as well as their effectors are being explored as possible therapeutic targets in the treatment of RAS mutant cancer. The two Ral isoforms, RalA and RalB, interact with a variety of downstream effectors and have been found to play key and distinct roles in both normal and neoplastic cell physiology including regulation of vesicular trafficking, migration and invasion, tumor formation, metastasis, and gene expression. In this review we provide an overview of Ral biochemistry and biology, and we highlight recent discoveries.
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Affiliation(s)
- Leanna R Gentry
- University of North Carolina at Chapel Hill, Department of Pharmacology, Chapel Hill, NC, USA
| | | | - David J Reiner
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX, USA
| | - Channing J Der
- University of North Carolina at Chapel Hill, Department of Pharmacology, Chapel Hill, NC, USA; University of North Carolina at Chapel Hill, Lineberger Comprehensive Cancer Center, Chapel Hill, NC, USA.
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19
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Pribic J, Brazill D. Paxillin phosphorylation and complexing with Erk and FAK are regulated by PLD activity in MDA-MB-231 cells. Cell Signal 2012; 24:1531-40. [PMID: 22481092 DOI: 10.1016/j.cellsig.2012.03.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Revised: 03/20/2012] [Accepted: 03/20/2012] [Indexed: 10/28/2022]
Abstract
MDA-MB-231 cells are highly aggressive human breast adenocarcinoma cells that depend on PLD activity for survival. In response to the stress of serum withdrawal, there is increased motility and invasiveness of these cells that is associated with a rapid increase in PLD activity. In addition, PLD activity is elevated in response to most mitogenic signals. Similar to PLD, paxillin, a focal adhesion adaptor protein, and Erk, mitogen-activated protein kinase, play vital roles in cell motility through regulation of focal adhesion dynamics. Here, we addressed whether there is a functional correlation between paxillin and PLD that may influence cancer cell motility. We investigated the role of PLD activity on paxillin regulation, Erk activation and formation of a paxillin-Erk and paxillin-FAK association. Inhibition of PLD activity led to an increase in paxillin tyrosine phosphorylation, a decrease in Erk activation, as measured by phosphorylation, and enhanced association of paxillin with Erk. In addition, we found that paxillin tyrosine phosphorylation depends upon Erk activity and may be a consequence of an increased association with FAK. Taken together, these results suggest that Erk activity is governed by PLD activity and regulates the tyrosine phosphorylation of paxillin, potentially explaining its role in cell motility. This study indicated that PLD, Erk, paxillin and FAK participate in the same signaling pathway in this breast cancer cell line.
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Affiliation(s)
- Jelena Pribic
- Graduate Center and Department of Biological Sciences, Hunter College, The City University of New York, New York, NY 10065, United States
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20
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21
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Abstract
All bacterial toxins, which globally are hydrophilic proteins, interact first with their target cells by recognizing a surface receptor, which is either a lipid or a lipid derivative, or another compound but in a lipid environment. Intracellular active toxins follow various trafficking pathways, the sorting of which is greatly dependent on the nature of the receptor, notably lipidic receptor or receptor embedded into a distinct environment such as lipid microdomains. Numerous other toxins act locally on cell membrane. Indeed, phospholipase activity is a common mechanism shared by several membrane-damaging toxins. In addition, many toxins active intracellularly or on cell membrane modulate host cell phospholipid pathways. Unusually, a few bacterial toxins require a lipid post-translational modification to be active. Thereby, lipids are obligate partners of bacterial toxins.
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Affiliation(s)
- Blandine Geny
- Unité des Bactéries Anaérobies et Toxines, Institut Pasteur, 28 rue du Dr Roux, 75724 Paris cedex 15, France
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22
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Obinata D, Takayama KI, Urano T, Murata T, Ikeda K, Horie-Inoue K, Ouchi Y, Takahashi S, Inoue S. ARFGAP3, an androgen target gene, promotes prostate cancer cell proliferation and migration. Int J Cancer 2011; 130:2240-8. [PMID: 21647875 DOI: 10.1002/ijc.26224] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Accepted: 05/23/2011] [Indexed: 01/04/2023]
Abstract
ADP ribosylation factor GTPase-activating protein 3 (ARFGAP3) is a GTPase-activating protein that associates with the Golgi apparatus and regulates the vesicular trafficking pathway. In the present study, we examined the contribution of ARFGAP3 to prostate cancer cell biology. We showed that ARFGAP3 expression was induced by 100 nM of dihydrotestosterone (DHT) at both the mRNA and protein levels in androgen-sensitive LNCaP cells. We generated stable transfectants of LNCaP cells with FLAG-tagged ARFGAP3 or a control empty vector and showed that ARFGAP3 overexpression promoted cell proliferation and migration compared with control cells. We found that ARFGAP3 interacted with paxillin, a focal adhesion adaptor protein that is important for cell mobility and migration. Small interfering RNA (siRNA)-mediated knockdown of ARFGAP3 showed that ARFGAP3 siRNA markedly reduced LNCaP cell growth. Androgen receptor (AR)-dependent transactivation activity on prostate-specific antigen (PSA) enhancer was synergistically promoted by exogenous ARFGAP3 and paxillin expression, as shown by luciferase assay in LNCaP cells. Thus, our results suggest that ARFGAP3 is a novel androgen-regulated gene that can promote prostate cancer cell proliferation and migration in collaboration with paxillin.
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Affiliation(s)
- Daisuke Obinata
- Department of Anti-Aging Medicine, The University of Tokyo, Tokyo, Japan
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23
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Xu L, Salloum D, Medlin PS, Saqcena M, Yellen P, Perrella B, Foster DA. Phospholipase D mediates nutrient input to mammalian target of rapamycin complex 1 (mTORC1). J Biol Chem 2011; 286:25477-86. [PMID: 21622984 DOI: 10.1074/jbc.m111.249631] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mammalian target of rapamycin (mTOR) is a critical sensor of nutritional sufficiency. Although much is known about the regulation of mTOR in response to growth factors, much less is known about the regulation of mTOR in response to nutrients. Amino acids have no impact on the signals that regulate Rheb, a GTPase required for the activation of mTOR complex 1 (mTORC1). Phospholipase D (PLD) generates a metabolite, phosphatidic acid, that facilitates association between mTOR and the mTORC1 co-factor Raptor. We report here that elevated PLD activity in human cancer cells is dependent on both amino acids and glucose and that amino acid- and glucose-induced increases in mTORC1 activity are dependent on PLD. Amino acid- and glucose-induced PLD and mTORC1 activity were also dependent on the GTPases RalA and ARF6 and the type III phosphatidylinositol-3-kinase hVps34. Thus, a key stimulatory event for mTORC1 activation in response to nutrients is the generation of phosphatidic acid by PLD.
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Affiliation(s)
- Limei Xu
- Department of Biological Sciences, Hunter College of the City University of New York, New York, New York 10065, USA
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24
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Abstract
As glucose is known to induce insulin secretion in pancreatic Beta cells, this study investigated the role of a phospholipase D (PLD)-related signaling pathway in insulin secretion caused by high glucose in the pancreatic Beta-cell line MIN6N8. It was found that the PLD activity and PLD1 expression were both increased by high glucose (33.3 mM) treatment. The dominant negative PLD1 inhibited glucose-induced Beta2 expression, and glucose-induced insulin secretion was blocked by treatment with 1-butanol or PLD1-siRNA. These results suggest that high glucose increased insulin secretion through a PLD1-related pathway. High glucose induced the binding of Arf6 to PLD1. Pretreatment with brefeldin A (BFA), an Arf inhibitor, decreased the PLD activity as well as the insulin secretion. Furthermore, BFA blocked the glucose-induced mTOR and p70S6K activation, while mTOR inhibition with rapamycin attenuated the glucose induced Beta2 expression and insulin secretion. Thus, when taken together, PLD1 would appear to be an important regulator of glucose-induced insulin secretion through an Arf6/PLD1/mTOR/p70S6K/ Beta2 pathway in MIN6N8 cells.
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Affiliation(s)
- Wei-na Ma
- Department of Biochemistry and Molecular Biology, College of Medicine, Hanyang University, Seoul 133-791, Korea
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25
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Corrotte M, Nyguyen APT, Harlay ML, Vitale N, Bader MF, Grant NJ. Ral isoforms are implicated in Fc gamma R-mediated phagocytosis: activation of phospholipase D by RalA. J Immunol 2010; 185:2942-50. [PMID: 20679536 DOI: 10.4049/jimmunol.0903138] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Phagocytosis is an essential element of the immune response permitting the elimination of pathogens, cellular debris, apoptotic cells, and tumor cells. Recently, both phospholipase D (PLD) isoforms, PLD1 and PLD2, were shown to be necessary for efficient FcgammaR-mediated phagocytosis. In this study, we investigated the role of a potential PLD regulator, the Ral GTPases RalA and RalB, in murine RAW 264.7 macrophages. Both Ral isoforms are expressed in macrophages and are transiently activated following FcgammaR stimulation. When Ral expression levels were varied using Ral mutants or interference RNA, phagocytosis assays revealed that Ral isoforms have antagonistic effects; RalA is a positive modulator, whereas RalB plays a negative role. We then focused on RalA and its possible relationship with PLD. The increase in PLD activity that occurs when phagocytosis is stimulated was inhibited in cells with reduced RalA protein, but it was unaffected by reduced levels of RalB. Furthermore, in macrophages transfected with dsRed-RalA and GFP-PLD1 or GFP-PLD2, RalA colocalized with PLD1 and PLD2 at the phagocytic cup during phagosome formation. Additional results obtained from immunoprecipitation of PLD from macrophages transfected with myc-RalA and hemagglutinin-tagged PLD1 or PLD2 indicated an enhanced interaction of RalA with both PLD isoforms during phagocytic stimulation. The increase in RalA and PLD1 interaction was transient and correlated with the time course of RalA activation. These findings reveal a novel pathway involving RalA and PLD in the regulation of FcgammaR-mediated phagocytosis.
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Affiliation(s)
- Matthias Corrotte
- Département Neurotransmission et Sécrétion Neuroendocrine, Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique, Unité Propre de Recherche 3212, Strasbourg, France
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26
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Popoff MR, Poulain B. Bacterial toxins and the nervous system: neurotoxins and multipotential toxins interacting with neuronal cells. Toxins (Basel) 2010; 2:683-737. [PMID: 22069606 PMCID: PMC3153206 DOI: 10.3390/toxins2040683] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2010] [Revised: 03/18/2010] [Accepted: 04/07/2010] [Indexed: 12/13/2022] Open
Abstract
Toxins are potent molecules used by various bacteria to interact with a host organism. Some of them specifically act on neuronal cells (clostridial neurotoxins) leading to characteristics neurological affections. But many other toxins are multifunctional and recognize a wider range of cell types including neuronal cells. Various enterotoxins interact with the enteric nervous system, for example by stimulating afferent neurons or inducing neurotransmitter release from enterochromaffin cells which result either in vomiting, in amplification of the diarrhea, or in intestinal inflammation process. Other toxins can pass the blood brain barrier and directly act on specific neurons.
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Affiliation(s)
- Michel R. Popoff
- Neurotransmission et Sécrétion Neuroendocrine, CNRS UPR 2356 IFR 37 - Neurosciences, Centre de Neurochimie, 5, rue Blaise Pascal, F-67084 STRASBOURG cedex, France;
- Author to whom correspondence should be addressed;
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27
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Ceriani M, Amigoni L, Scandiuzzi C, Berruti G, Martegani E. The PH-PxxP domain of RalGPS2 promotes PC12 cells differentiation acting as a dominant negative for RalA GTPase activation. Neurosci Res 2009; 66:290-8. [PMID: 20025911 DOI: 10.1016/j.neures.2009.11.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Revised: 11/11/2009] [Accepted: 11/30/2009] [Indexed: 10/20/2022]
Abstract
RalGPS2 is a guanine nucleotide exchange factor for RalA GTPase characterized by a C-terminal Pleckstrin Homology (PH) domain; this GEF is endogenously expressed in PC12 cells and in rat brain but its role in PC12 cells and in cell differentiation is actually unknown. Here we have shown that transient expression of RalGPS2-PH-PxxP domain in PC12 and PC12-TrkA cells induces high level of neurite outgrowth; this differentiation is comparable with that of PC12 cells treated with RalGPS2 siRNA. Stable PC12 cell lines expressing the PH-PxxP domain of RalGPS2 have been generated; in these cell lines the PH-PxxP domain acts as a dominant negative for RalA activation, promotes cells differentiation and re-directs NGF signals towards MAPKs. Furthermore it has been also demonstrated that the PH-PxxP domain of RalGPS2 induces microspikes formation a typical feature of cells in which the Cdc42 GTPase is constitutively activated.
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Affiliation(s)
- Michela Ceriani
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, Milan, Italy
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28
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Godin CM, Ferreira LT, Dale LB, Gros R, Cregan SP, Ferguson SSG. The Small GTPase Ral Couples the Angiotensin II Type 1 Receptor to the Activation of Phospholipase C-δ1. Mol Pharmacol 2009; 77:388-95. [DOI: 10.1124/mol.109.061069] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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29
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Ljubicic S, Bezzi P, Vitale N, Regazzi R. The GTPase RalA regulates different steps of the secretory process in pancreatic beta-cells. PLoS One. 2009;4:e7770. [PMID: 19890390 PMCID: PMC2766836 DOI: 10.1371/journal.pone.0007770] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Accepted: 10/11/2009] [Indexed: 12/25/2022] Open
Abstract
Background RalA and RalB are multifuntional GTPases involved in a variety of cellular processes including proliferation, oncogenic transformation and membrane trafficking. Here we investigated the mechanisms leading to activation of Ral proteins in pancreatic β-cells and analyzed the impact on different steps of the insulin-secretory process. Methodology/Principal Findings We found that RalA is the predominant isoform expressed in pancreatic islets and insulin-secreting cell lines. Silencing of this GTPase in INS-1E cells by RNA interference led to a decrease in secretagogue-induced insulin release. Real-time measurements by fluorescence resonance energy transfer revealed that RalA activation in response to secretagogues occurs within 3–5 min and reaches a plateau after 10–15 min. The activation of the GTPase is triggered by increases in intracellular Ca2+ and cAMP and is prevented by the L-type voltage-gated Ca2+ channel blocker Nifedipine and by the protein kinase A inhibitor H89. Defective insulin release in cells lacking RalA is associated with a decrease in the secretory granules docked at the plasma membrane detected by Total Internal Reflection Fluorescence microscopy and with a strong impairment in Phospholipase D1 activation in response to secretagogues. RalA was found to be activated by RalGDS and to be severely hampered upon silencing of this GDP/GTP exchange factor. Accordingly, INS-1E cells lacking RalGDS displayed a reduction in hormone secretion induced by secretagogues and in the number of insulin-containing granules docked at the plasma membrane. Conclusions/Significance Taken together, our data indicate that RalA activation elicited by the exchange factor RalGDS in response to a rise in intracellular Ca2+ and cAMP controls hormone release from pancreatic β-cell by coordinating the execution of different events in the secretory pathway.
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Bader MF, Vitale N. Phospholipase D in calcium-regulated exocytosis: Lessons from chromaffin cells. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:936-41. [DOI: 10.1016/j.bbalip.2009.02.016] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2008] [Revised: 02/23/2009] [Accepted: 02/26/2009] [Indexed: 10/21/2022]
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Garcia A, Zheng Y, Zhao C, Toschi A, Fan J, Shraibman N, Brown HA, Bar-Sagi D, Foster DA, Arbiser JL. Honokiol suppresses survival signals mediated by Ras-dependent phospholipase D activity in human cancer cells. Clin Cancer Res 2008; 14:4267-74. [PMID: 18594009 DOI: 10.1158/1078-0432.ccr-08-0102] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
PURPOSE Elevated phospholipase D (PLD) activity provides a survival signal in several human cancer cell lines and suppresses apoptosis when cells are subjected to the stress of serum withdrawal. Thus, targeting PLD survival signals has potential to suppress survival in cancer cells that depend on PLD for survival. Honokiol is a compound that suppresses tumor growth in mouse models. The purpose of this study was to investigate the effect of honokiol on PLD survival signals and the Ras dependence of these signals. EXPERIMENTAL DESIGN The effect of honokiol upon PLD activity was examined in human cancer cell lines where PLD activity provides a survival signal. The dependence of PLD survival signals on Ras was investigated, as was the effect of honokiol on Ras activation. RESULTS We report here that honokiol suppresses PLD activity in human cancer cells where PLD has been shown to suppress apoptosis. PLD activity is commonly elevated in response to the stress of serum withdrawal, and, importantly, the stress-induced increase in PLD activity is selectively suppressed by honokiol. The stress-induced increase in PLD activity was accompanied by increased Ras activation, and the stress-induced increase in PLD activity in MDA-MB-231 breast cancer cells was dependent on a Ras. The PLD activity was also dependent on the GTPases RalA and ADP ribosylation factor. Importantly, honokiol suppressed Ras activation. CONCLUSION The data provided here indicate that honokiol may be a valuable therapeutic reagent for targeting a large number of human cancers that depend on Ras and PLD for their survival.
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Affiliation(s)
- Avalon Garcia
- Department of Biological Sciences, Hunter College of The City University of New York, New York 10021, USA
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Sun Y, Fang Y, Yoon MS, Zhang C, Roccio M, Zwartkruis FJ, Armstrong M, Brown HA, Chen J. Phospholipase D1 is an effector of Rheb in the mTOR pathway. Proc Natl Acad Sci U S A 2008; 105:8286-91. [PMID: 18550814 DOI: 10.1073/pnas.0712268105] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The mammalian target of rapamycin (mTOR) assembles a signaling network essential for the regulation of cell growth, which has emerged as a major target of anticancer therapies. The tuberous sclerosis complex 1 and 2 (TSC1/2) proteins and their target, the small GTPase Rheb, constitute a key regulatory pathway upstream of mTOR. Phospholipase D (PLD) and its product phosphatidic acid are also upstream regulators of the mitogenic mTOR signaling. However, how the TSC/Rheb and PLD pathways interact or integrate in the rapamycin-sensitive signaling network has not been examined before. Here, we find that PLD1, but not PLD2, is required for Rheb activation of the mTOR pathway, as demonstrated by the effects of RNAi. The overexpression of Rheb activates PLD1 in cells in the absence of mitogenic stimulation, and the knockdown of Rheb impairs serum stimulation of PLD activation. Furthermore, the overexpression of TSC2 suppresses PLD1 activation, whereas the knockdown or deletion of TSC2 leads to elevated basal activity of PLD. Consistent with a TSC-Rheb-PLD signaling cascade, AMPK and PI3K, both established regulators of TSC2, appear to lie upstream of PLD as revealed by the effects of pharmacological inhibitors, and serum activation of PLD is also dependent on amino acid sufficiency. Finally, Rheb binds and activates PLD1 in vitro in a GTP-dependent manner, strongly suggesting that PLD1 is a bona fide effector for Rheb. Hence, our findings reveal an unexpected interaction between two cascades in the mTOR signaling pathways and open up additional possibilities for targeting this important growth-regulating network for the development of anticancer drugs.
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Shi M, Zheng Y, Garcia A, Xu L, Foster DA. Phospholipase D provides a survival signal in human cancer cells with activated H-Ras or K-Ras. Cancer Lett 2007; 258:268-75. [PMID: 17949898 DOI: 10.1016/j.canlet.2007.09.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Revised: 07/12/2007] [Accepted: 09/11/2007] [Indexed: 02/04/2023]
Abstract
Phospholipase D (PLD) is elevated in rodent fibroblasts expressing activated H-Ras mutants. We therefore examined the PLD activity in human cancer cells with activating Ras mutations. T24 bladder carcinoma cells express an activated H-Ras gene and Calu-1 lung carcinoma cells express an activated K-Ras gene. We report here that both of these cancer cell lines express highly elevated levels of PLD activity and that the PLD activity is dependent upon Ras. We also show that the PLD activity is dependent upon the Ras effector molecules RalA and phosphatidylinositol-3-kinase (PI3K). PLD activity has been shown to provide a survival signal in breast cancer cell lines that suppressed stress-induced apoptosis. Suppression of PLD activity in the T24 and Calu-1 cells resulted in apoptotic cell death in the absence of serum, indicating that the elevated PLD activity provided a survival signal in these cancer cell lines. Suppression of Ras, RalA, or PI3K also led to apoptosis in the absence of serum. These data indicate that a critical component of Ras signaling in human cancer cells is the activation of PLD and that targeting PLD survival signals in cancer cells could be an effective strategy to induce apoptosis in human cancers with activating Ras mutations.
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Ceriani M, Scandiuzzi C, Amigoni L, Tisi R, Berruti G, Martegani E. Functional analysis of RalGPS2, a murine guanine nucleotide exchange factor for RalA GTPase. Exp Cell Res 2007; 313:2293-307. [PMID: 17462626 DOI: 10.1016/j.yexcr.2007.03.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2006] [Revised: 03/14/2007] [Accepted: 03/18/2007] [Indexed: 11/28/2022]
Abstract
RalGPS2 is a murine guanine nucleotide exchange factor of the RalGPS family; it contains a Cdc25-like GEF domain and does not exhibit a Ras-binding domain. The main characteristic of RalGPS2 is its pleckstrin homology (PH) domain, present at the C terminus, that preferentially binds phosphatidylinositol-4,5-biphosphate and in HEK 293 cells localized in membranes, causing ruffling and vesiculation. Moreover, RalGPS2 contains a PxxP motif in the central part of the molecule. This motif binds in vitro and in vivo SH3 domains of Grb2 and PLCgamma. RalGPS2 and its GEF domain activate RalA in vivo while the PH-PxxP domains inhibited it behaving as a dominant negative for the RalA pathway; this activation was not inhibited by co-expression of a dominant negative Ras. RalGPS2 is physiologically expressed in testis and brain; when overexpressed, the whole RalGPS2 causes considerable morphological changes in HEK 293 cells, suggesting its possible role on cytoskeleton reorganization. This is further strengthened by data obtained in NIH3T3 cells where expression of PH-PxxP domain promotes actin depolymerization. Finally, RalGPS2 and its GEF domain induce Ras-independent transcriptional activation of the c-fos promoter in NIH3T3 cells.
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Affiliation(s)
- Michela Ceriani
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, Milan, Italy
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Abstract
Scatter factor (SF) (hepatocyte growth factor) is a pleiotrophic cytokine that accumulates within tumors in vivo and protects tumor cells against cytotoxicity and apoptosis due to DNA damaging agents in vitro. Previous studies have established that SF-mediated cell protection involves antiapoptotic signaling from its receptor (c-Met) to PI3 kinase --> c-Akt --> Pak1 (p21-activated kinase -1) --> NF-kappaB (nuclear factor-kappa B). Here, we found that Ras proteins (H-Ras and R-Ras) enhance SF-mediated activation of NF-kappaB and protection of DU-145 and MDCK (Madin-Darby canine kidney) cells against the topoisomerase IIalpha inhibitor adriamycin. Studies of Ras effector loop mutants and their downstream effectors suggest that Ras/PI3 kinase and Ras/Raf1 pathways contribute to SF stimulation of NF-kappaB signaling and cell protection. Further studies revealed that Raf1 positively regulates the ability of SF to stimulate NF-kappaB activity and cell protection. The ability of Raf1 to stimulate NF-kappaB activity was not due to the classical Raf1 --> MEK1/2 --> ERK1/2 pathway. However, we found that a MEK3/6 --> p38 pathway contributes to SF-mediated activation of NF-kappaB. In contrast, RalA, a target of the Ras/RalGDS pathway negatively regulated the ability of SF to stimulate NF-kappaB activity and cell protection. Ras, Raf1 and RalA modulate SF stimulation of NF-kappaB activity, in part, by regulating IkappaB kinase (IKK)-beta kinase activity. These findings suggest that Ras/Raf1/RalA pathways may converge to modulate NF-kappaB activation and SF-mediated survival signaling at the IKK complex and/or a kinase upstream of this complex.
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Affiliation(s)
- S Fan
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057-1469, USA
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Jilkina O, Bhullar RP. A serine kinase associates with the RAL GTPase and phosphorylates RAL-interacting protein 1. Biochimica et Biophysica Acta (BBA) - Molecular Cell Research 2006; 1763:948-57. [PMID: 16945434 DOI: 10.1016/j.bbamcr.2006.07.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2006] [Revised: 07/11/2006] [Accepted: 07/13/2006] [Indexed: 02/02/2023]
Abstract
A kinase activity that phosphorylated myelin basic protein in vitro was detected in RalA and RalB immunoprecipitates from human platelets. Protein-protein interaction studies using recombinant GST-RalA, GST-RalB and GST-cH-Ras confirmed that the kinase specifically associates with the Ral GTPase. The Ral Interacting Protein 1 (RIP1), a GTPase Activating Protein (GAP) for Cdc42 and Rac1, was found to be the preferred substrate for the Ral Interacting Kinase (RIK). Phosphoamino acid analysis demonstrated that RIK phosphorylated serine residue in RIP1. The Ral-RIK interaction was not dependent on the guanine nucleotide status of Ral. RIK was detected in a variety of rat tissues with testis containing the highest and skeletal muscle the lowest activity. In-gel kinase renaturation assay using RIP1 as the substrate demonstrated that the kinase activity was associated with polypeptides of molecular mass of approximately 36-40 kDa and was detected in most rat tissues with a prominent 38 kDa band in testis and a 40 kDa band in brain. Human platelets contained a single band of approximately 36 kDa. RIK was distinct from MAPKs, CDKs, cyclic AMP dependent protein kinase and Ca2+/calmodulin dependent kinases. To demonstrate in vivo interaction, the endogenous Ral-RIK complex was isolated using a calmodulin affinity column. The Ral-RIK complex co-eluted from this column upon washing with a 13 residue peptide that encompasses the calmodulin-binding domain in RalA. The data suggest that RIK is a serine specific kinase that phosphorylates RIP1 and is constitutively associated with Ral. The current study provides additional support for a link between Ral and the Cdc42/Rac1 signalling pathways in the cell.
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Affiliation(s)
- Olga Jilkina
- Department of Oral Biology, University of Manitoba, Winnipeg, Manitoba, Canada R3E 0W2
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Abstract
This article reports the identification and characterization of a DBL-like guanine nucleotide exchange factor (GEF) in Drosophila, called GEFmeso, as a novel binding target of the Ras-like GTPase Ral. Previous studies suggested that some aspects of Ral activity, which is involved in multiple cellular processes, are mediated through regulation of Rho GTPases. Here we show in vitro association of GEFmeso with the GTP-bound active form of Ral and the nucleotide-free form of the Rho GTPase Cdc42. GEFmeso fails to bind to other Rho GTPases, showing that Cdc42 is a specific interaction partner of this GEF. Unlike Ral and Cdc42, which are ubiquitously expressed, GEFmeso exerts distinct spatio-temporal expression patterns during embryonic development, suggesting a tissue-restricted function of the GEF in vivo. Based on previous observations that mutations in Cdc42 or overexpression of mutant alleles of Cdc42 lead to distinct effects on wing development, the effects of overexpression of dominant-negative and activated versions of Ral on wing development were analyzed. In addition, GEFmeso overexpression studies as well as RNAi experiments were performed. The results suggest that Ral, GEFmeso and Cdc42 act in the same developmental pathway and that GEFmeso mediates activation of Cdc42 in response to activated Ral in the context of Drosophila wing development.
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Affiliation(s)
- Stephen Blanke
- Abteilung Molekulare Entwicklungsbiologie, Max-Planck-Institut für biophysikalische Chemie, Göttingen, Germany
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Zheng Y, Rodrik V, Toschi A, Shi M, Hui L, Shen Y, Foster DA. Phospholipase D couples survival and migration signals in stress response of human cancer cells. J Biol Chem 2006; 281:15862-8. [PMID: 16595654 DOI: 10.1074/jbc.m600660200] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.1] [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] [Indexed: 01/23/2023] Open
Abstract
MDA-MB-231 human breast cancer cells belong to a highly invasive metastatic cell line that depends on phospholipase D (PLD) activity for survival when deprived of serum growth factors. In response to the stress of serum withdrawal, there is a rapid and dramatic increase in PLD activity. Concomitant with increased PLD activity, there was an increase in the ability of MDA-MB-231 cells to both migrate and invade Matrigel. The ability of MDA-MB-231 cells to both migrate and invade Matrigel was dependent on both PLD and mTOR, a downstream target of PLD signals. Serum withdrawal also led to a PLD-dependent increase in the expression of the stress factor, hypoxia-inducible factor-1alpha. These data reveal that PLD survival signals not only prevent apoptosis but also stimulate cell migration and invasion, linking the ability to suppress apoptosis with the ability to metastasize.
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Affiliation(s)
- Yang Zheng
- Department of Biological Sciences, Hunter College of the City University of New York, New York, New York 10021, USA
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Abstract
Neurite branching is essential for the establishment of appropriate neuronal connections during development and regeneration. We identify the small GTPase Ral as a mediator of neurite branching. Active Ral promotes neurite branching in cortical and sympathetic neurons, whereas Ral inhibition decreases laminin-induced branching. In addition, depletion of endogenous Ral by RNA interference decreases branching in cortical neurons. The two Ral isoforms, RalA and -B, promote branching through distinct pathways, involving the exocyst complex and phospholipase D, respectively. Finally, Ral-dependent branching is mediated by protein kinase C-dependent phosphorylation of 43-kD growth-associated protein, a crucial molecule involved in pathfinding, plasticity, and regeneration. These findings highlight an important role for Ral in the regulation of neuronal morphology.
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Affiliation(s)
- Giovanna Lalli
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, England, UK
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Pautsch A, Vogelsgesang M, Tränkle J, Herrmann C, Aktories K. Crystal structure of the C3bot-RalA complex reveals a novel type of action of a bacterial exoenzyme. EMBO J 2005; 24:3670-80. [PMID: 16177825 PMCID: PMC1276701 DOI: 10.1038/sj.emboj.7600813] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2005] [Accepted: 08/22/2005] [Indexed: 12/21/2022] Open
Abstract
C3 exoenzymes from bacterial pathogens ADP-ribosylate and inactivate low-molecular-mass GTPases of the Rho subfamily. Ral, a Ras subfamily GTPase, binds the C3 exoenzymes from Clostridium botulinum and C. limosum with high affinity without being a substrate for ADP ribosylation. In the complex, the ADP-ribosyltransferase activity of C3 is blocked, while binding of NAD and NAD-glycohydrolase activity remain. Here we report the crystal structure of C3 from C. botulinum in a complex with GDP-bound RalA at 1.8 A resolution. C3 binds RalA with a helix-loop-helix motif that is adjacent to the active site. A quaternary complex with NAD suggests a mode for ADP-ribosyltransferase inhibition. Interaction of C3 with RalA occurs at a unique interface formed by the switch-II region, helix alpha3 and the P loop of the GTPase. C3-binding stabilizes the GDP-bound conformation of RalA and blocks nucleotide release. Our data indicate that C. botulinum exoenzyme C3 is a single-domain toxin with bifunctional properties targeting Rho GTPases by ADP ribosylation and Ral by a guanine nucleotide dissociation inhibitor-like effect, which blocks nucleotide exchange.
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Affiliation(s)
- Alexander Pautsch
- Structural Research, Department of Integrated Lead Discovery, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Martin Vogelsgesang
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie der Universität Freiburg, Otto-Krayer-Haus, Freiburg, Germany
| | - Jens Tränkle
- Physikalische Chemie I, Ruhr-Universität Bochum, Bochum, Germany
| | | | - Klaus Aktories
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie der Universität Freiburg, Otto-Krayer-Haus, Freiburg, Germany
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie der Universität Freiburg, Otto-Krayer-Haus, Albertstrasse 25, 79104 Freiburg, Germany. Tel.: +49 761 203 5301; Fax: +49 761 203 5311; E-mail:
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Gomez GA, Daniotti JL. H-Ras dynamically interacts with recycling endosomes in CHO-K1 cells: involvement of Rab5 and Rab11 in the trafficking of H-Ras to this pericentriolar endocytic compartment. J Biol Chem 2005; 280:34997-5010. [PMID: 16079139 DOI: 10.1074/jbc.m506256200] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [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: 11/06/2022] Open
Abstract
H-, N-, and K-Ras are isoforms of Ras proteins, which undergo different lipid modifications at the C terminus. These post-translational events make possible the association of Ras proteins both with the inner plasma membrane and to the cytosolic surface of endoplasmic reticulum and Golgi complex, which is also required for the proper function of these proteins. To better characterize the intracellular distribution and sorting of Ras proteins, constructs were engineered to express the C-terminal domain of H- and K-Ras fused to variants of green fluorescent protein. Using confocal microscopy, we found in CHO-K1 cells that H-Ras, which is palmitoylated and farnesylated, localized at the recycling endosome in addition to the inner leaflet of the plasma membrane. In contrast, K-Ras, which is farnesylated and nonpalmitoylated, mainly localized at the plasma membrane. Moreover, we demonstrate that sorting signals of H- and K-Ras are contained within the C-terminal domain of these proteins and that palmitoylation on this region of H-Ras might operate as a dominant sorting signal for proper subcellular localization of this protein in CHO-K1 cells. Using selective photobleaching techniques, we demonstrate the dynamic nature of H-Ras trafficking to the recycling endosome from plasma membrane. We also provide evidence that Rab5 and Rab11 activities are required for proper delivery of H-Ras to the endocytic recycling compartment. Using a chimera containing the Ras binding domain of c-Raf-1 fused to a fluorescent protein, we found that a pool of GTP-bound H-Ras localized on membranes from Rab11-positive recycling endosome after serum stimulation. These results suggest that H-Ras present in membranes of the recycling endosome might be activating signal cascades essential for the dynamic and function of the organelle.
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Affiliation(s)
- Guillermo Alberto Gomez
- Centro de Investigaciones en Química Biológica de Córdoba, CIQUIBIC (UNC-CONICET), Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba 5000, Argentina
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Abstract
The phosphorylation sites in phospholipase D2 (PLD2) induced by activation of protein kinase Calpha (PKCalpha) in COS 7 cells were analyzed by mass spectrometry. Ser134, 146, and 243, and Thr72, 99/100, and 252 were identified. These sites were mutated to Ala and the double mutation of Ser243 and Thr252 eliminated the phosphorylation. However, the PLD2 activity, and the binding between PKCalpha and PLD2 were unaffected by the mutations. We conclude that phosphorylation of these residues is not required for PLD2 activation by PKCalpha, and that protein-protein interaction between PLD2 and PKCalpha is sufficient to activate PLD2.
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Affiliation(s)
- Jun-Song Chen
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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Vitale N, Mawet J, Camonis J, Regazzi R, Bader MF, Chasserot-Golaz S. The Small GTPase RalA controls exocytosis of large dense core secretory granules by interacting with ARF6-dependent phospholipase D1. J Biol Chem 2005; 280:29921-8. [PMID: 15980073 DOI: 10.1074/jbc.m413748200] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [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: 11/06/2022] Open
Abstract
RalA and RalB constitute a family of highly similar Ras-related GTPases widely distributed in different tissues. Recently, active forms of Ral proteins have been shown to bind to the exocyst complex, implicating them in the regulation of cellular secretion. Since RalA is present on the plasma membrane in neuroendocrine chromaffin and PC12 cells, we investigated the potential role of RalA in calcium-regulated exocytotic secretion. We show here that endogenous RalA is activated during exocytosis. Expression of the constitutively active RalA (G23V) mutant enhances secretagogue-evoked secretion from PC12 cells. Conversely, expression of the constitutively inactive GDP-bound RalA (G26A) or silencing of the RalA gene by RNA interference led to a strong impairment of the exocytotic response. RalA was found to co-localize with phospholipase D1 (PLD1) at the plasma membrane in PC12 cells. We demonstrate that cell stimulation triggers a direct interaction between RalA and ARF6-activated PLD1. Moreover, reduction of endogenous RalA expression level interfered with the activation of PLD1 observed in secretagogue-stimulated cells. Finally, using various RalA mutants selectively impaired in their ability to activate downstream effectors, we show that PLD1 activation is essential for the activation of secretion by GTP-loaded RalA. Together, these results provide evidence that RalA is a positive regulator of calcium-evoked exocytosis of large dense core secretory granules and suggest that stimulation of PLD1 and consequent changes in plasma membrane phospholipid composition is the major function RalA undertakes in calcium-regulated exocytosis.
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Affiliation(s)
- Nicolas Vitale
- Centre National de la Recherche Scientifique, Unité Propre de Recherche 2356 Neurotransmission and Sécrétion Neuroendocrine, Strasbourg France
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Abstract
Second messengers generated from membrane lipids play a critical role in signaling and control diverse cellular processes. Despite being one of the most evolutionarily conserved of all the phosphoinositide-specific phospholipase C (PLC) isoforms, a family of enzymes responsible for hydrolysis of the membrane lipid phosphatidylinositol bisphosphate, the mechanism of PLC-delta1 activation is still poorly understood. Here we report a novel regulatory mechanism for PLC-delta1 activation that involves direct interaction of the small GTPase Ral and the universal calcium-signaling molecule calmodulin (CaM) with PLC-delta1. In addition, we have identified a novel IQ type CaM binding motif within the catalytic region of PLC-delta1 that is not found in other PLC isoforms. Binding of CaM at the IQ motif inhibits PLC-delta1 activity, while addition of Ral reverses the inhibition. The overexpression of various Ral mutants in cells potentiates PLC-delta1 activity. Thus, the Ral-CaM complex defines a multifaceted regulatory mechanism for PLC-delta1 activation.
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Affiliation(s)
- Ranjinder S Sidhu
- Department of Oral Biology, Faculty of Dentistry, University of Manitoba, Winnipeg, Manitoba R3E 0W2, Canada
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Ho WT, Xie Z, Zhao ZJ, Exton JH. Tyrosine phosphorylation of phospholipase D1 by v-Src does not per se result in activation. Cell Signal 2005; 17:691-9. [PMID: 15722193 DOI: 10.1016/j.cellsig.2004.10.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [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: 08/24/2004] [Accepted: 10/11/2004] [Indexed: 10/26/2022]
Abstract
The relationship between tyrosine phosphorylation and activation of phospholipase D1 (PLD1) by v-Src was examined. Co-expression of v-Src and PLD1 in COS-7 cells resulted in increased activity and marked tyrosine phosphorylation of PLD1. PLD activity was increased in membranes or immunoprecipitates prepared from these cells. Dephosphorylation of the immunoprecipitated enzyme by tyrosine phosphatase or phosphorylation by c-Src produced no changes in its activity. Tyrosine phosphorylation induced by v-Src caused a shift of the enzyme from the Triton-soluble to the Triton-insoluble fraction. v-Src and PLD1 could be co-immunoprecipitated from cells co-expressing these and were co-localized in the perinuclear region as assessed by immunofluorescence. Mutation of the palmitoylation sites of PLD1 significantly reduced tyrosine phosphorylation by v-Src. It is concluded that tyrosine phosphorylation of PLD1 by v-Src does not per se alter its activity. It is proposed that activation of PLD1 by v-Src in vivo may involve association/colocalization of the two proteins.
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Affiliation(s)
- Wan-Ting Ho
- Howard Hughes Medical Institute and the Department of Molecular Physiology and Biophysics, Room 831 Light Hall, Vanderbilt University School of Medicine, Nashville, TN 37232, United States
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Bhattacharya M, Babwah AV, Godin C, Anborgh PH, Dale LB, Poulter MO, Ferguson SSG. Ral and phospholipase D2-dependent pathway for constitutive metabotropic glutamate receptor endocytosis. J Neurosci 2005; 24:8752-61. [PMID: 15470141 PMCID: PMC6729950 DOI: 10.1523/jneurosci.3155-04.2004] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [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: 11/21/2022] Open
Abstract
G-protein-coupled receptors play a central role in the regulation of neuronal cell communication. Class 1 metabotropic glutamate receptors (mGluRs) mGluR1a and mGluR5a, which are coupled with the hydrolysis of phosphoinositides, are essential for modulating excitatory neurotransmission at glutamatergic synapses. These receptors are constitutively internalized in heterologous cell cultures, neuronal cultures, and intact neuronal tissues. We show here that the small GTP-binding protein Ral, its guanine nucleotide exchange factor RalGDS (Ral GDP dissociation stimulator), and phospholipase D2 (PLD2) are constitutively associated with class 1 mGluRs and regulate constitutive mGluR endocytosis. Moreover, both Ral and PLD2 are colocalized with mGluRs in endocytic vesicles in both human embryonic kidney 293 (HEK 293) cells and neurons. Ral and PLD2 activity is required for the internalization of class 1 mGluRs but is not required for the internalization of the beta2-adrenergic receptor. Constitutive class 1 mGluR internalization is not dependent on the downstream Ral effector proteins Ral-binding protein 1 and PLD1 or either ADP-ribosylation factors ARF1 or ARF6. The treatment of HEK 293 cells and neurons with small interfering RNA both downregulates PLD2 expression and blocks mGluR1a and mGluR5a endocytosis. The constitutive internalization of mGluR1a and mGluR5a is also attenuated by the treatment of cells with 1-butanol to prevent PLD2-mediated phosphatidic acid formation. We propose that the formation of a mGluR-scaffolded RalGDS/Ral/PLD2 protein complex provides a novel alternative mechanism to beta-arrestins for the constitutive endocytosis of class 1 mGluRs.
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Affiliation(s)
- Moshmi Bhattacharya
- Cell Biology Research Group, Robarts Research Institute, London, Ontario, Canada N6A 5K8
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Frankel P, Aronheim A, Kavanagh E, Balda MS, Matter K, Bunney TD, Marshall CJ. RalA interacts with ZONAB in a cell density-dependent manner and regulates its transcriptional activity. EMBO J 2005; 24:54-62. [PMID: 15592429 PMCID: PMC544910 DOI: 10.1038/sj.emboj.7600497] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2004] [Accepted: 11/05/2004] [Indexed: 11/08/2022] Open
Abstract
Ral proteins are members of the Ras superfamily of small GTPases and are involved in signalling pathways for actin cytoskeleton remodelling, cell cycle control, cellular transformation and vesicle transport. To identify novel RalA effector proteins, we used the reverse Ras recruitment system and found that RalA interacts with a Y-box transcription factor, ZO-1-associated nucleic acid-binding protein (ZONAB), in a GTP-dependent manner. The amount of the RalA-ZONAB complex increases as epithelial cells become more dense and increase cell contacts. The RalA-ZONAB interaction results in a relief of transcriptional repression of a ZONAB-regulated promoter. Additionally, expression of oncogenic Ras alleviates transcriptional repression by ZONAB in a RalA-dependent manner. The data presented here implicate the RalA/ZONAB interaction in the regulation of ZONAB function.
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Affiliation(s)
- Paul Frankel
- Oncogene Team, Cancer Research UK Centre for Cell and Molecular Biology, Chester Beatty Laboratories, Institute of Cancer Research, London, UK
| | - Ami Aronheim
- Department of Molecular Genetics, the B Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Emma Kavanagh
- Division of Cell Biology, Institute of Ophthalmology, University College London, London, UK
| | - Maria S Balda
- Division of Cell Biology, Institute of Ophthalmology, University College London, London, UK
| | - Karl Matter
- Division of Cell Biology, Institute of Ophthalmology, University College London, London, UK
| | - Tom D Bunney
- Lipid Signalling Team, Cancer Research UK Centre for Cell and Molecular Biology, Chester Beatty Laboratories, Institute of Cancer Research, London, UK
| | - Christopher J Marshall
- Oncogene Team, Cancer Research UK Centre for Cell and Molecular Biology, Chester Beatty Laboratories, Institute of Cancer Research, London, UK
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Abstract
Phospholipase D catalyses the hydrolysis of the phosphodiester bond of glycerophospholipids to generate phosphatidic acid and a free headgroup. Phospholipase D activities have been detected in simple to complex organisms from viruses and bacteria to yeast, plants, and mammals. Although enzymes with broader selectivity are found in some of the lower organisms, the plant, yeast, and mammalian enzymes are selective for phosphatidylcholine. The two mammalian phospholipase D isoforms are regulated by protein kinases and GTP binding proteins of the ADP-ribosylation and Rho families. Mammalian and yeast phospholipases D are also potently stimulated by phosphatidylinositol 4,5-bisphosphate. This review discusses the identification, characterization, structure, and regulation of phospholipase D. Genetic and pharmacological approaches implicate phospholipase D in a diverse range of cellular processes that include receptor signaling, control of intracellular membrane transport, and reorganization of the actin cytoskeleton. Most ideas about phospholipase D function consider that the phosphatidic acid product is an intracellular lipid messenger. Candidate targets for phospholipase-D-generated phosphatidic acid include phosphatidylinositol 4-phosphate 5-kinases and the raf protein kinase. Phosphatidic acid can also be converted to two other lipid mediators, diacylglycerol and lyso phosphatidic acid. Coordinated activation of these phospholipase-D-dependent pathways likely accounts for the pleitropic roles for these enzymes in many aspects of cell regulation.
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Affiliation(s)
- Mark McDermott
- Department of Cell and Developmental Biology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, 27599-7090, USA
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Abstract
C3-like exoenzymes comprise a family of seven bacterial ADP-ribosyltransferases, which selectively modify RhoA, B, and C at asparagine-41. Crystal structures of C3 exoenzymes are available, allowing novel insights into the structure-function relationships of these exoenzymes. Because ADP-ribosylation specifically inhibits the biological functions of the low-molecular mass GTPases, C3 exoenzymes are established pharmacological tools to study the cellular functions of Rho GTPases. Recent studies, however, indicate that the functional consequences of C3-induced ADP-ribosylation are more complex than previously suggested. In the present review the basic properties of C3 exoenzymes are briefly summarized and new findings are reviewed.
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Affiliation(s)
- K Aktories
- Institute of Experimental and Clinical Pharmacology and Toxicology, Albert-Ludwigs University Freiburg, Otto-Krayer-Haus, Albertstr. 25, Freiburg, Germany.
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Bounacer A, McGregor A, Skinner J, Bond J, Poghosyan Z, Wynford-Thomas D. Mutant ras-induced proliferation of human thyroid epithelial cells requires three effector pathways. Oncogene 2004; 23:7839-45. [PMID: 15361839 DOI: 10.1038/sj.onc.1208085] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [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: 11/08/2022]
Abstract
Ras mutations occur as an early event in many human tumours of epithelial origin, including thyroid. Using primary human thyroid epithelial cells to model tumour initiation by Ras, we have shown previously that activation of both the MAP kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K) effector pathways are necessary, but even when activated together are not sufficient, for Ras-induced proliferation. Here, we show that a third effector, RalGEF, is also activated by Ras in these cells, that this activation is necessary for Ras-induced proliferation, and furthermore that in combination with the MAPK and PI3K effectors, it is able to reproduce the proliferative effect of activated Ras. The requirement for three effector pathways indicates a more robust control of cell proliferation in this normal human epithelial cell type than has been displayed in previous similar studies using rodent and human cell lines. Our findings highlight the importance of the appropriate cellular context in models of Ras-induced tumour development.
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Affiliation(s)
- Ali Bounacer
- Cancer Research UK Laboratories, Department of Pathology, University of Wales College of Medicine, Cardiff CF14 4XN, UK
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