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Castillo S, Gence R, Pagan D, Koraïchi F, Bouchenot C, Pons BJ, Boëlle B, Olichon A, Lajoie-Mazenc I, Favre G, Pédelacq JD, Cabantous S. Visualizing the subcellular localization of RHOB-GTP and GTPase-Effector complexes using a split-GFP/nanobody labelling assay. Eur J Cell Biol 2023; 102:151355. [PMID: 37639782 DOI: 10.1016/j.ejcb.2023.151355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 08/04/2023] [Accepted: 08/20/2023] [Indexed: 08/31/2023] Open
Abstract
Small GTPases are highly regulated proteins that control essential signaling pathways through the activity of their effector proteins. Among the RHOA subfamily, RHOB regulates peculiar functions that could be associated with the control of the endocytic trafficking of signaling proteins. Here, we used an optimized assay based on tripartite split-GFP complementation to localize GTPase-effector complexes with high-resolution. The detection of RHOB interaction with the Rhotekin Rho binding domain (RBD) that specifically recognizes the active GTP-bound GTPase, is performed in vitro by the concomitant addition of recombinant GFP1-9 and a GFP nanobody. Analysis of RHOB-RBD complexes localization profiles combined with immunostaining and live cell imaging indicated a serum-dependent reorganization of the endosomal and membrane pool of active RHOB. We further applied this technology to the detection of RHO-effector complexes that highlighted their subcellular localization with high resolution among the different cellular compartments.
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Affiliation(s)
- Sebastian Castillo
- Centre de Recherche en Cancérologie de Toulouse (CRCT), INSERM, Université de Toulouse, UPS, CNRS, 31037 Toulouse, France
| | - Rémi Gence
- Centre de Recherche en Cancérologie de Toulouse (CRCT), INSERM, Université de Toulouse, UPS, CNRS, 31037 Toulouse, France
| | - Delphine Pagan
- Centre de Recherche en Cancérologie de Toulouse (CRCT), INSERM, Université de Toulouse, UPS, CNRS, 31037 Toulouse, France
| | - Faten Koraïchi
- Centre de Recherche en Cancérologie de Toulouse (CRCT), INSERM, Université de Toulouse, UPS, CNRS, 31037 Toulouse, France
| | | | - Benoit J Pons
- Environment and Sustainability Institute, Biosciences, University of Exeter, Penryn TR10 9FE, United Kingdom
| | - Betty Boëlle
- Centre de Recherche en Cancérologie de Toulouse (CRCT), INSERM, Université de Toulouse, UPS, CNRS, 31037 Toulouse, France
| | - Aurélien Olichon
- Université de la Réunion, INSERM, UMR 1188 Diabète Athérothrombose Thérapies Réunion Océan Indien (DéTROI), 97410 Saint-Pierre, La Réunion, France
| | - Isabelle Lajoie-Mazenc
- Centre de Recherche en Cancérologie de Toulouse (CRCT), INSERM, Université de Toulouse, UPS, CNRS, 31037 Toulouse, France
| | - Gilles Favre
- Centre de Recherche en Cancérologie de Toulouse (CRCT), INSERM, Université de Toulouse, UPS, CNRS, 31037 Toulouse, France
| | - Jean-Denis Pédelacq
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UPS), Toulouse, France
| | - Stéphanie Cabantous
- Centre de Recherche en Cancérologie de Toulouse (CRCT), INSERM, Université de Toulouse, UPS, CNRS, 31037 Toulouse, France.
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Bery N, Keller L, Soulié M, Gence R, Iscache AL, Cherier J, Cabantous S, Sordet O, Lajoie-Mazenc I, Pedelacq JD, Favre G, Olichon A. A Targeted Protein Degradation Cell-Based Screening for Nanobodies Selective toward the Cellular RHOB GTP-Bound Conformation. Cell Chem Biol 2019; 26:1544-1558.e6. [PMID: 31522999 DOI: 10.1016/j.chembiol.2019.08.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Revised: 11/22/2018] [Accepted: 08/23/2019] [Indexed: 01/10/2023]
Abstract
The selective downregulation of activated intracellular proteins is a key challenge in cell biology. RHO small GTPases switch between a guanosine diphosphate (GDP)-bound and a guanosine triphosphate (GTP)-bound state that drives downstream signaling. At present, no tool is available to study endogenous RHO-GTPinduced conformational changes in live cells. Here, we established a cell-based screen to selectively degrade RHOB-GTP using F-box-intracellular single-domain antibody fusion. We identified one intracellular antibody (intrabody) that shows selective targeting of endogenous RHOB-GTP mediated by interactions between the CDR3 loop of the domain antibody and the GTP-binding pocket of RHOB. Our results suggest that, while RHOB is highly regulated at the expression level, only the GTP-bound pool, but not its global expression, mediates RHOB functions in genomic instability and in cell invasion. The F-box/intrabody-targeted protein degradation represents a unique approach to knock down the active form of small GTPases or other proteins with multiple cellular activities.
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Affiliation(s)
- Nicolas Bery
- Centre de Recherche en Cancérologie de Toulouse (CRCT), INSERM, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Laura Keller
- Centre de Recherche en Cancérologie de Toulouse (CRCT), INSERM, Université de Toulouse, CNRS, UPS, Toulouse, France; Département de Biologie, Institut Claudius Regaud, Toulouse, France
| | - Marjorie Soulié
- Centre de Recherche en Cancérologie de Toulouse (CRCT), INSERM, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Rémi Gence
- Centre de Recherche en Cancérologie de Toulouse (CRCT), INSERM, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Anne-Laure Iscache
- Centre de Recherche en Cancérologie de Toulouse (CRCT), INSERM, Université de Toulouse, CNRS, UPS, Toulouse, France; Département de Biologie, Institut Claudius Regaud, Toulouse, France
| | - Julia Cherier
- Centre de Recherche en Cancérologie de Toulouse (CRCT), INSERM, Université de Toulouse, CNRS, UPS, Toulouse, France; Département de Biologie, Institut Claudius Regaud, Toulouse, France
| | - Stéphanie Cabantous
- Centre de Recherche en Cancérologie de Toulouse (CRCT), INSERM, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Olivier Sordet
- Centre de Recherche en Cancérologie de Toulouse (CRCT), INSERM, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Isabelle Lajoie-Mazenc
- Centre de Recherche en Cancérologie de Toulouse (CRCT), INSERM, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Jean-Denis Pedelacq
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, Toulouse, France.
| | - Gilles Favre
- Centre de Recherche en Cancérologie de Toulouse (CRCT), INSERM, Université de Toulouse, CNRS, UPS, Toulouse, France; Département de Biologie, Institut Claudius Regaud, Toulouse, France.
| | - Aurélien Olichon
- Centre de Recherche en Cancérologie de Toulouse (CRCT), INSERM, Université de Toulouse, CNRS, UPS, Toulouse, France.
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Koraïchi F, Gence R, Bouchenot C, Grosjean S, Lajoie-Mazenc I, Favre G, Cabantous S. High-content tripartite split-GFP cell-based assays to screen for modulators of small GTPase activation. J Cell Sci 2018; 131:jcs.210419. [PMID: 29192060 PMCID: PMC5818064 DOI: 10.1242/jcs.210419] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 11/28/2017] [Indexed: 01/12/2023] Open
Abstract
The human Ras superfamily of small GTPases controls essential cellular processes such as gene expression and cell proliferation. As their deregulation is widely associated with human cancer, small GTPases and their regulatory proteins have become increasingly attractive for the development of novel therapeutics. Classical methods to monitor GTPase activation include pulldown assays that limit the analysis of GTP-bound form of proteins from cell lysates. Alternatively, live-cell FRET biosensors may be used to study GTPase activation dynamics in response to stimuli, but these sensors often require further optimization for high-throughput applications. Here, we describe a cell-based approach that is suitable to monitor the modulation of small GTPase activity in a high-content analysis. The assay relies on a genetically encoded tripartite split-GFP (triSFP) system that we integrated in an optimized cellular model to monitor modulation of RhoA and RhoB GTPases. Our results indicate the robust response of the reporter, allowing the interrogation of inhibition and stimulation of Rho activity, and highlight potential applications of this method to discover novel modulators and regulators of small GTPases and related protein-binding domains. Summary: The development of a fluorescent reporter of GTPase activation based on tripartite split-GFP that enables the evaluation of GEF activity and the effect of modulators of GTPase activation in a high-content analysis.
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Affiliation(s)
- Faten Koraïchi
- Cancer Research Center of Toulouse, INSERM U1037, 31037 Toulouse, France.,Université de Toulouse, Toulouse, France
| | - Rémi Gence
- Cancer Research Center of Toulouse, INSERM U1037, 31037 Toulouse, France.,Université de Toulouse, Toulouse, France
| | - Catherine Bouchenot
- Cancer Research Center of Toulouse, INSERM U1037, 31037 Toulouse, France.,Université de Toulouse, Toulouse, France
| | - Sarah Grosjean
- Cancer Research Center of Toulouse, INSERM U1037, 31037 Toulouse, France.,Université de Toulouse, Toulouse, France
| | - Isabelle Lajoie-Mazenc
- Cancer Research Center of Toulouse, INSERM U1037, 31037 Toulouse, France.,Université de Toulouse, Toulouse, France
| | - Gilles Favre
- Cancer Research Center of Toulouse, INSERM U1037, 31037 Toulouse, France .,Université de Toulouse, Toulouse, France
| | - Stéphanie Cabantous
- Cancer Research Center of Toulouse, INSERM U1037, 31037 Toulouse, France .,Université de Toulouse, Toulouse, France
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Teiti I, Florie B, Pich C, Gence R, Lajoie-Mazenc I, Rochaix P, Favre G, Tilkin-Mariamé AF. In vivo Effects in Melanoma of ROCK Inhibition-Induced FasL Overexpression. Front Oncol 2015; 5:156. [PMID: 26236689 PMCID: PMC4500923 DOI: 10.3389/fonc.2015.00156] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [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: 03/05/2015] [Accepted: 06/29/2015] [Indexed: 01/12/2023] Open
Abstract
Ectopic Fas-ligand (FasL) expression in tumor cells is responsible for both tumor escape through tumor counterattack of Fas-positive infiltrating lymphocytes and tumor rejection though inflammatory and immune responses. We have previously shown that RhoA GTPase and its effector ROCK negatively control FasL membrane expression in murine melanoma B16F10 cells. In this study, we found that B16F10 treatment with the ROCK inhibitor H1152 reduced melanoma development in vivo through FasL membrane overexpression. Although H1152 treatment did not reduce tumor growth in vitro, pretreatment of tumor cells with this inhibitor delayed tumor appearance, and slowed tumor growth in C57BL/6 immunocompetent mice. Thanks to the use of mice-bearing mutated Fas receptors (B6/lpr), we found that reduced tumor growth, observed in immunocompetent mice, was linked to FasL overexpression induced by H1152 treatment. Tumor growth analysis in immunosuppressed NUDE and IFN-γ-KO mice highlighted major roles for T lymphocytes and IFN-γ in the H1152-induced tumor growth reduction. Histological analyses of subcutaneous tumors, obtained from untreated versus H1152-treated B16F10 cells, showed that H1152 pretreatment induced a strong intratumoral infiltration of leukocytes. Cytofluorometric analysis showed that among these leukocytes, the number of activated CD8 lymphocytes was increased. Moreover, their antibody-induced depletion highlighted their main responsibility in tumor growth reduction. Subcutaneous tumor growth was also reduced by repeated intravenous injections of a clinical ROCK inhibitor, Fasudil. Finally, H1152-induced ROCK inhibition also reduced pulmonary metastasis implantation independently of T cell-mediated immune response. Altogether, our data suggest that ROCK inhibitors could become interesting pharmacological molecules for melanoma immunotherapy.
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Affiliation(s)
- Iotefa Teiti
- Unité INSERM UMR 1037, CRCT , Toulouse , France ; Université Paul Sabatier , Toulouse , France
| | - Bertrand Florie
- Unité INSERM UMR 1037, CRCT , Toulouse , France ; Université Paul Sabatier , Toulouse , France
| | - Christine Pich
- Unité INSERM UMR 1037, CRCT , Toulouse , France ; Université Paul Sabatier , Toulouse , France
| | - Rémi Gence
- Unité INSERM UMR 1037, CRCT , Toulouse , France ; Université Paul Sabatier , Toulouse , France
| | - Isabelle Lajoie-Mazenc
- Unité INSERM UMR 1037, CRCT , Toulouse , France ; Université Paul Sabatier , Toulouse , France
| | - Philippe Rochaix
- Université Paul Sabatier , Toulouse , France ; Institut Universitaire du Cancer de Toulouse , Toulouse , France
| | - Gilles Favre
- Unité INSERM UMR 1037, CRCT , Toulouse , France ; Université Paul Sabatier , Toulouse , France ; Institut Universitaire du Cancer de Toulouse , Toulouse , France
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Bertrand F, Rochotte J, Colacios C, Montfort A, Tilkin-Mariamé AF, Touriol C, Rochaix P, Lajoie-Mazenc I, Andrieu-Abadie N, Levade T, Benoist H, Ségui B. Blocking Tumor Necrosis Factor α Enhances CD8 T-cell–Dependent Immunity in Experimental Melanoma. Cancer Res 2015; 75:2619-28. [DOI: 10.1158/0008-5472.can-14-2524] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 04/22/2015] [Indexed: 11/16/2022]
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Médale-Giamarchi C, Lajoie-Mazenc I, Malissein E, Meunier E, Couderc B, Bergé Y, Filleron T, Keller L, Marty C, Lacroix-Triki M, Dalenc F, Doisneau-Sixou SF, Favre G. RhoB modifies estrogen responses in breast cancer cells by influencing expression of the estrogen receptor. Breast Cancer Res 2013; 15:R6. [PMID: 23339407 PMCID: PMC3672819 DOI: 10.1186/bcr3377] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Accepted: 01/10/2013] [Indexed: 02/07/2023] Open
Abstract
INTRODUCTION RhoB has been reported to exert positive and negative effects on cancer pathophysiology but an understanding of its role in breast cancer remains incomplete. Analysis of data from the Oncomine database showed a positive correlation between RhoB expression and positivity for both estrogen receptor alpha (ERα) and progesterone receptor (PR). METHODS This finding was validated by our analysis of a tissue microarray constructed from a cohort of 113 patients and then investigated in human cell models. RESULTS We found that RhoB expression in tissue was strongly correlated with ERα and PR expression and inversely correlated with tumor grade, tumor size and count of mitosis. In human breast cancer cell lines, RhoB attenuation was associated with reduced expression of both ERα and PR, whereas elevation of RhoB was found to be associated with ERα overexpression. Mechanistic investigations suggested that RhoB modulates ERα expression, controlling both its protein and mRNA levels, and that RhoB modulates PR expression by accentuating the recruitment of ERα and other major co-regulators to the promoter of PR gene. A major consequence of RhoB modulation was that RhoB differentially regulated the proliferation of breast cancer cell lines. Interestingly, we documented crosstalk between RhoB and ERα, with estrogen treatment leading to RhoB activation. CONCLUSION Taken together, our findings offer evidence that in human breast cancer RhoB acts as a positive function to promote expression of ERα and PR in a manner correlated with cell proliferation.
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Rotaru V, Lajoie-Mazenc I, Tollon Y, Raynaud-Messina B, Jean C, Détraves C, Julian M, Moisand A, Wright M. Condensation-decondensation of the γ-tubulin containing material in the absence of a structurally visible organelle during the cell cycle of Physarum plasmodia. Biol Cell 2012. [DOI: 10.1111/j.1768-322x.1999.tb01096.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Chinestra P, Lajoie-Mazenc I, Faye JC, Favre G. Use of phage display for the identification of molecular sensors specific for activated Rho. Methods Mol Biol 2012; 827:283-303. [PMID: 22144282 DOI: 10.1007/978-1-61779-442-1_19] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
We describe a phage display approach to select active Rho-specific scFv sensors. This in vitro technique allows preserving the antigen conformation stability all along the selection process. We used the GTP locked RhoBQ63L mutant as antigen against the Griffin.1 library composed of a human synthetic V(H) + V(L) scFv cloned in the pHEN2 phagemid vector. The method described here has permitted to identify an scFv that discriminates between the activated and the inactivated form of the Rho subfamily.
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Affiliation(s)
- Patrick Chinestra
- INSERM UMR 1037, Cancer Research Centre of Toulouse, Claudius Regaud Cancer Institute, University of Toulouse, Toulouse, France
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Malissein E, Meunier E, Bouliong-Pillai E, Berge Y, Lajoie-Mazenc I, Balaguer P, Favre G, Dalenc F, Doisneau-Sixou S. RhoB controls estrogen receptor target genes expression through a modulation of ER recruitment on the promoter binding sites, in MCF- 7 cells. EJC Suppl 2008. [DOI: 10.1016/s1359-6349(08)71251-5] [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: 10/21/2022] Open
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Goffinet M, Chinestra P, Lajoie-Mazenc I, Medale-Giamarchi C, Favre G, Faye JC. Identification of a GTP-bound Rho specific scFv molecular sensor by phage display selection. BMC Biotechnol 2008; 8:34. [PMID: 18377644 PMCID: PMC2323369 DOI: 10.1186/1472-6750-8-34] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [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: 07/13/2007] [Accepted: 03/31/2008] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND The Rho GTPases A, B and C proteins, members of the Rho family whose activity is regulated by GDP/GTP cycling, function in many cellular pathways controlling proliferation and have recently been implicated in tumorigenesis. Although overexpression of Rho GTPases has been correlated with tumorigenesis, only their GTP-bound forms are able to activate the signalling pathways implicated in tumorigenesis. Thus, the focus of much recent research has been to identify biological tools capable of quantifying the level of cellular GTP-bound Rho, or determining the subcellular location of activation. However useful, these tools used to study the mechanism of Rho activation still have limitations. The aim of the present work was to employ phage display to identify a conformationally-specific single chain fragment variable (scFv) that recognizes the active, GTP-bound, form of Rho GTPases and is able to discriminate it from the inactive, GDP-bound, Rho in endogenous settings. RESULTS After five rounds of phage selection using a constitutively activated mutant of RhoB (RhoBQ63L), three scFvs (A8, C1 and D11) were selected for subsequent analysis. Further biochemical characterization was pursued for the single clone, C1, exhibiting an scFv structure. C1 was selective for the GTP-bound form of RhoA, RhoB, as well as RhoC, and failed to recognize GTP-loaded Rac1 or Cdc42, two other members of the Rho family. To enhance its production, soluble C1 was expressed in fusion with the N-terminal domain of phage protein pIII (scFv C1-N1N2), it appeared specifically associated with GTP-loaded recombinant RhoA and RhoB via immunoprecipitation, and endogenous activated Rho in HeLa cells as determined by immunofluorescence. CONCLUSION We identified an antibody, C1-N1N2, specific for the GTP-bound form of RhoB from a phage library, and confirmed its specificity towards GTP-bound RhoA and RhoC, as well as RhoB. The success of C1-N1N2 in discriminating activated Rho in immunofluorescence studies implies that this new tool, in collaboration with currently used RhoA and B antibodies, has the potential to analyze Rho activation in cell function and tumor development.
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Affiliation(s)
- Marine Goffinet
- NSERM U563, CPTP, "Signalisation cellulaire, GTPase Rho et cancers", F-31052, Toulouse, France
- Institut Claudius Regaud, Département de Biologie, F-31052, Toulouse, France
- Université Paul Sabatier, Faculté des Sciences Pharmaceutiques, F-31062, Toulouse, France
| | - Patrick Chinestra
- NSERM U563, CPTP, "Signalisation cellulaire, GTPase Rho et cancers", F-31052, Toulouse, France
- Institut Claudius Regaud, Département de Biologie, F-31052, Toulouse, France
- Université Paul Sabatier, Faculté des Sciences Pharmaceutiques, F-31062, Toulouse, France
| | - Isabelle Lajoie-Mazenc
- NSERM U563, CPTP, "Signalisation cellulaire, GTPase Rho et cancers", F-31052, Toulouse, France
- Institut Claudius Regaud, Département de Biologie, F-31052, Toulouse, France
- Université Paul Sabatier, Faculté des Sciences Pharmaceutiques, F-31062, Toulouse, France
| | - Claire Medale-Giamarchi
- NSERM U563, CPTP, "Signalisation cellulaire, GTPase Rho et cancers", F-31052, Toulouse, France
- Institut Claudius Regaud, Département de Biologie, F-31052, Toulouse, France
- Université Paul Sabatier, Faculté des Sciences Pharmaceutiques, F-31062, Toulouse, France
| | - Gilles Favre
- NSERM U563, CPTP, "Signalisation cellulaire, GTPase Rho et cancers", F-31052, Toulouse, France
- Institut Claudius Regaud, Département de Biologie, F-31052, Toulouse, France
- Université Paul Sabatier, Faculté des Sciences Pharmaceutiques, F-31062, Toulouse, France
| | - Jean-Charles Faye
- NSERM U563, CPTP, "Signalisation cellulaire, GTPase Rho et cancers", F-31052, Toulouse, France
- Institut Claudius Regaud, Département de Biologie, F-31052, Toulouse, France
- Université Paul Sabatier, Faculté des Sciences Pharmaceutiques, F-31062, Toulouse, France
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Lajoie-Mazenc I, Tovar D, Penary M, Lortal B, Allart S, Favard C, Brihoum M, Pradines A, Favre G. MAP1A light chain-2 interacts with GTP-RhoB to control epidermal growth factor (EGF)-dependent EGF receptor signaling. J Biol Chem 2007; 283:4155-64. [PMID: 18056259 DOI: 10.1074/jbc.m709639200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [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
Rho GTPases have been implicated in the control of several cellular functions, including regulation of the actin cytoskeleton, cell proliferation, and oncogenesis. Unlike RhoA and RhoC, RhoB localizes in part to endosomes and controls endocytic trafficking. Using a yeast two-hybrid screen and a glutathione S-transferase pulldown assay, we identified LC2, the light chain of the microtubule-associated protein MAP1A, as a novel binding partner for RhoB. GTP binding and the 18-amino acid C-terminal hypervariable domain of RhoB are critical for its binding to MAP1A/LC2. Coimmunoprecipitation and immunofluorescence experiments showed that this interaction occurs in U87 cells. Down-regulation of MAP1A/LC2 expression decreased epidermal growth factor (EGF) receptor expression and modified the signaling response to EGF treatment. We concluded that MAP1A/LC2 is critical for RhoB function in EGF-induced EGF receptor regulation. Because MAP1A/LC2 is thought to function as an adaptor between microtubules and other molecules, we postulate that the RhoB and MAP1A/LC2 interactions facilitate endocytic vesicle trafficking and regulate the trafficking of signaling molecules.
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Affiliation(s)
- Isabelle Lajoie-Mazenc
- INSERM U563, Département Oncogénèse, Signalisation et Innovation Thérapeutique, Toulouse F-31059, France.
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Goffinet M, Thoulouzan M, Pradines A, Lajoie-Mazenc I, Weinbaum C, Faye JC, Séronie-Vivien S. Zoledronic acid treatment impairs protein geranyl-geranylation for biological effects in prostatic cells. BMC Cancer 2006; 6:60. [PMID: 16539721 PMCID: PMC1434759 DOI: 10.1186/1471-2407-6-60] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [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: 02/02/2006] [Accepted: 03/15/2006] [Indexed: 12/01/2022] Open
Abstract
Background Nitrogen-containing bisphosphonates (N-BPs) have been designed to inhibit osteoclast-mediated bone resorption. However, it is now accepted that part of their anti-tumor activities is related to interference with the mevalonate pathway. Methods We investigated the effects of zoledronic acid (ZOL), on cell proliferation and protein isoprenylation in two tumoral (LnCAP, PC-3,), and one normal established (PNT1-A) prostatic cell line. To assess if inhibition of geranyl-geranylation by ZOL impairs the biological activity of RhoA GTPase, we studied the LPA-induced formation of stress fibers. The inhibitory effect of ZOL on geranyl geranyl transferase I was checked biochemically. Activity of ZOL on cholesterol biosynthesis was determined by measuring the incorporation of 14C mevalonate in cholesterol. Results ZOL induced dose-dependent inhibition of proliferation of all the three cell lines although it appeared more efficient on the untransformed PNT1A. Whatever the cell line, 20 μM ZOL-induced inhibition was reversed by geranyl-geraniol (GGOH) but neither by farnesol nor mevalonate. After 48 hours treatment of cells with 20 μM ZOL, geranyl-geranylation of Rap1A was abolished whereas farnesylation of HDJ-2 was unaffected. Inhibition of Rap1A geranyl-geranylation by ZOL was rescued by GGOH and not by FOH. Indeed, as observed with treatment by a geranyl-geranyl transferase inhibitor, treatment of PNT1-A cells with 20 μM ZOL prevented the LPA-induced formation of stress fibers. We checked that in vitro ZOL did not inhibit geranyl-geranyl-transferase I. ZOL strongly inhibited cholesterol biosynthesis up to 24 hours but at 48 hours 90% of this biosynthesis was rescued. Conclusion Although zoledronic acid is currently the most efficient bisphosphonate in metastatic prostate cancer management, its mechanism of action in prostatic cells remains unclear. We suggest in this work that although in first intention ZOL inhibits FPPsynthase its main biological actitivity is directed against protein Geranylgeranylation.
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Affiliation(s)
- M Goffinet
- Inserm U563, Centre de Physiopathologie de Toulouse Purpan, Département "Innovation Thérapeutique et Oncologie Moléculaire", Institut Claudius Regaud, Toulouse, France
| | - M Thoulouzan
- Inserm U563, Centre de Physiopathologie de Toulouse Purpan, Département "Innovation Thérapeutique et Oncologie Moléculaire", Institut Claudius Regaud, Toulouse, France
| | - A Pradines
- Inserm U563, Centre de Physiopathologie de Toulouse Purpan, Département "Innovation Thérapeutique et Oncologie Moléculaire", Institut Claudius Regaud, Toulouse, France
| | - I Lajoie-Mazenc
- Inserm U563, Centre de Physiopathologie de Toulouse Purpan, Département "Innovation Thérapeutique et Oncologie Moléculaire", Institut Claudius Regaud, Toulouse, France
| | - Carolyn Weinbaum
- Duke University, Medical Center Department of Pharmacology & Cancer Biology, Durham, NC, USA
| | - JC Faye
- Inserm U563, Centre de Physiopathologie de Toulouse Purpan, Département "Innovation Thérapeutique et Oncologie Moléculaire", Institut Claudius Regaud, Toulouse, France
| | - S Séronie-Vivien
- Inserm U563, Centre de Physiopathologie de Toulouse Purpan, Département "Innovation Thérapeutique et Oncologie Moléculaire", Institut Claudius Regaud, Toulouse, France
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13
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Skuli N, Monferran S, Delmas C, Lajoie-Mazenc I, Favre G, Toulas C, Cohen-Jonathan-Moyal E. 110 Activation of RHOS by hypoxia controls HIF-1α stabilization through GSK-3 in glioblastoma. Radiother Oncol 2006. [DOI: 10.1016/s0167-8140(06)80589-x] [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: 11/24/2022]
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14
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Skuli N, Monferran S, Delmas C, Lajoie-Mazenc I, Favre G, Toulas C, Cohen-Jonathan-Moyal E. Activation of RhoB by Hypoxia Controls Hypoxia-Inducible Factor-1α Stabilization through Glycogen Synthase Kinase-3 in U87 Glioblastoma Cells. Cancer Res 2006; 66:482-9. [PMID: 16397264 DOI: 10.1158/0008-5472.can-05-2299] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [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: 11/16/2022]
Abstract
Hypoxia is a crucial factor in tumor aggressiveness and resistance to treatment, particularly in glioma. Our previous results have shown that inhibiting the small GTPase RhoB increased oxygenation of U87 human glioblastoma xenografts, in part, by regulating angiogenesis. We investigated here whether RhoB might also control a signaling pathway that would permit glioma cells to adapt to hypoxia. We first showed that silencing RhoB with siRNA induced degradation and inhibition of the transcriptional activity of the hypoxia-inducible factor by the proteasome in U87 hypoxic cells. This RhoB-dependent degradation of hypoxia-inducible factor-1alpha in hypoxic conditions was mediated by the Akt/glycogen synthase kinase-3beta pathway. While investigating how hypoxia could activate this signaling pathway, using the GST-Rhotekin RBD pulldown assay, we showed the early activation of RhoB by reactive oxygen species under hypoxic conditions and, subsequently, its participation in the ensuing cellular adaptation to hypoxia. Overall, therefore, our results have not only highlighted a new signaling pathway for hypoxia controlled by the small GTPase RhoB, but they also strongly implicate RhoB as a potentially important therapeutic target for decreasing tumor hypoxia.
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Affiliation(s)
- Nicolas Skuli
- Institut National de la Sante et de la Recherche Medicale U563, Departement d'Innovation Thérapeutique et Oncologie Moléculaire, Centre de Lutte Contre le Cancer Claudius Regaud, Toulouse Cedex, France
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15
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Canguilhem B, Pradines A, Baudouin C, Boby C, Lajoie-Mazenc I, Charveron M, Favre G. RhoB protects human keratinocytes from UVB-induced apoptosis through epidermal growth factor receptor signaling. J Biol Chem 2005; 280:43257-63. [PMID: 16278215 DOI: 10.1074/jbc.m508650200] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [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: 11/06/2022] Open
Abstract
Exposure of the skin to UVB light results in the formation of DNA photolesions that can give rise to cell death, mutations, and the onset of carcinogenic events. Specific proteins are activated by UVB and then trigger signal transduction pathways that lead to cellular responses. An alteration of these signaling molecules is thought to be a fundamental event in tumor promotion by UVB irradiation. RhoB, encoding a small GTPase has been identified as a DNA damage-inducible gene. RhoB is involved in epidermal growth factor (EGF) receptor trafficking, cytoskeletal organization, cell transformation, and survival. We have analyzed the regulation of RhoB and elucidated its role in the cellular response of HaCaT keratinocytes to relevant environmental UVB irradiation. We report here that the activated GTP-bound form of RhoB is increased rapidly within 5 min of exposure to UVB, and then RhoB protein levels increased concomitantly with EGF receptor (EGFR) activation. Inhibition of UVB-induced EGFR activation prevents RhoB protein expression and AKT phosphorylation but not the early activation of RhoB. Blocking UVB-induced RhoB expression with specific small interfering RNAs inhibits AKT and glycogen synthase kinase-3beta phosphorylation through inhibition of EGFR expression. Moreover, down-regulation of RhoB potentiates UVB-induced cell apoptosis. In contrast, RhoB overexpression protects keratinocytes against UVB-induced apoptosis. These results indicated that RhoB is regulated upon UVB exposure by a two-step process consisting of an early EGFR-independent RhoB activation followed by an EGFR-dependent induction of RhoB expression. Moreover, we have demonstrated that RhoB is essential in regulating keratinocyte cell survival after UVB exposure, suggesting its potential role in photocarcinogenesis.
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Affiliation(s)
- Bruno Canguilhem
- INSERM U563, Département Innovation Thérapeutique et Oncologie Moléculaire, Institut Claudius Regaud, Université Paul Sabatier, 20/24 rue du Pont Saint-Pierre, 31052 Toulouse Cedex France
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16
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Milia J, Teyssier F, Dalenc F, Ader I, Delmas C, Pradines A, Lajoie-Mazenc I, Baron R, Bonnet J, Cohen-Jonathan E, Favre G, Toulas C. Farnesylated RhoB inhibits radiation-induced mitotic cell death and controls radiation-induced centrosome overduplication. Cell Death Differ 2005; 12:492-501. [PMID: 15776002 DOI: 10.1038/sj.cdd.4401586] [Citation(s) in RCA: 32] [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] [Indexed: 11/09/2022] Open
Abstract
Our previous results demonstrated that expressing the GTPase ras homolog gene family, member B (RhoB) in radiosensitive NIH3T3 cells increases their survival following 2 Gy irradiation (SF2). We have first demonstrated here that RhoB expression inhibits radiation-induced mitotic cell death. RhoB is present in both a farnesylated and a geranylgeranylated form in vivo. By expressing RhoB mutants encoding for farnesylated (RhoB-F cells), geranylgeranylated or the CAAX deleted form of RhoB, we have then shown that only RhoB-F expression was able to increase the SF2 value by reducing the sensitivity of these cells to radiation-induced mitotic cell death. Moreover, RhoB-F cells showed an increased G2 arrest and an inhibition of centrosome overduplication following irradiation mediated by the Rho-kinase, strongly suggesting that RhoB-F may control centrosome overduplication during the G2 arrest after irradiation. Overall, our results for the first time clearly implicate farnesylated RhoB as a crucial protein in mediating cellular resistance to radiation-induced nonapoptotic cell death.
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Affiliation(s)
- J Milia
- INSERM U563, CPTP, Département d'Innovation Thérapeutique et d'Oncologie Moléculaire, Institut Claudius Regaud, 20-24 rue du Pont St Pierre, 31052 Toulouse Cedex, France
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17
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Tilkin-Mariamé AF, Cormary C, Ferro N, Sarrabayrouse G, Lajoie-Mazenc I, Faye JC, Favre G. Geranylgeranyl transferase inhibition stimulates antimelanoma immune response through MHC class I and costimulatory molecule expression. FASEB J 2005; 19:1513-5. [PMID: 15990392 DOI: 10.1096/fj.04-3482fje] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Defective antitumor immune responses are frequent consequences of defects in the expression of major histocompatibility complex (MHC) class I and costimulatory molecules. We demonstrated that statins, inhibitors of HMGCoA reductase, enhance mIFN-gamma induced expression of MHC class I antigens on murine B16F10 melanoma. GGTI-298, a geranylgeranyl transferase I inhibitor, but not FTI-277, a farnesyl transferase inhibitor, mimics this effect of statins. This effect is related to peptide transporter protein TAP1 up-regulation. Simultaneously, GGTI-298 induces the expression of CD80 and CD86 costimulatory molecules. C3 exoenzyme, which selectively inactivates Rho proteins, phenocopies the effects of GGTI-298, indicating a role for Rho proteins in these events. Furthermore, the treatment of B16F10 cells with GGTI-298 or C3 exoenzyme associated with mIFN-gamma induces in vivo tumor growth slowing down in immunocompetent but not in nu/nu syngeneic mice. Both in vivo injections and in vitro restimulation of splenocytes with GGTI-298- and mIFN-gamma-treated B16F10 cells induces an enhancement of specific CD8 T lymphocytes labeled by TRP-2/H-2K(b) tetramers. Finally, these effects are not limited to mouse models since they were also reproduced in two human melanoma cell lines. These observations indicate that protein geranylgeranylation as well as Rho protein are critical for costimulatory and IFN-gamma-dependent MHC class I molecule expression in melanoma.
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Affiliation(s)
- A-F Tilkin-Mariamé
- INSERM U563 CPTP, Département Innovation thérapeutique et Oncologie Moléculaire, Toulouse, France.
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18
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Baron R, Fourcade E, Lajoie-Mazenc I, Allal C, Couderc B, Barbaras R, Favre G, Faye JC, Pradines A. RhoB prenylation is driven by the three carboxyl-terminal amino acids of the protein: evidenced in vivo by an anti-farnesyl cysteine antibody. Proc Natl Acad Sci U S A 2000; 97:11626-31. [PMID: 11027361 PMCID: PMC17251 DOI: 10.1073/pnas.97.21.11626] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [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: 11/18/2022] Open
Abstract
Protein isoprenylation is a lipid posttranslational modification required for the function of many proteins that share a carboxyl-terminal CAAX motif. The X residue determines which isoprenoid will be added to the cysteine. When X is a methionine or serine, the farnesyl-transferase transfers a farnesyl, and when X is a leucine or isoleucine, the geranygeranyl-transferase I, a geranylgeranyl group. But despite its CKVL motif, RhoB was reported to be both geranylgeranylated and farnesylated. Thus, the determinants of RhoB prenylation appear more complex than initially thought. To determine the role of RhoB CAAX motif, we designed RhoB mutants with modified CAAX sequence expressed in baculovirus-infected insect cells. We demonstrated that RhoB was prenylated as a function of the three terminal amino acids, i.e., RhoB bearing the CAIM motif of lamin B or CLLL motif of Rap1A was farnesylated or geranylgeranylated, respectively. Next, we produced a specific polyclonal antibody against farnesyl cysteine methyl ester allowing prenylation analysis avoiding the metabolic labeling restrictions. We confirmed that the unique modification of the RhoB CAAX box was sufficient to direct the RhoB distinct prenylation in mammalian cells and, inversely, that a RhoA-CKVL chimera could be alternatively prenylated. Moreover, the immunoprecipitation of endogenous RhoB from cells with the anti-farnesyl cysteine antibody suggested that wild-type RhoB is farnesylated in vivo. Taken together, our results demonstrated that the three last carboxyl amino acids are the main determinants for RhoB prenylation and described an anti-farnesyl cysteine antibody as a useful tool for understanding the cellular control of protein farnesylation.
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Affiliation(s)
- R Baron
- Endocrinologie et Communications Cellulaires Institut National de la Santé et de la Recherche Médicale Unité 397, Toulouse, France
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19
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Allal C, Favre G, Couderc B, Salicio S, Sixou S, Hamilton AD, Sebti SM, Lajoie-Mazenc I, Pradines A. RhoA prenylation is required for promotion of cell growth and transformation and cytoskeleton organization but not for induction of serum response element transcription. J Biol Chem 2000; 275:31001-8. [PMID: 10896672 DOI: 10.1074/jbc.m005264200] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.3] [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: 11/06/2022] Open
Abstract
The importance of post-translational geranylgeranylation of the GTPase RhoA for its ability to induce cellular proliferation and malignant transformation is not well understood. In this manuscript we demonstrate that geranylgeranylation is required for the proper cellular localization of V14RhoA and for its ability to induce actin stress fiber and focal adhesion formation. Furthermore, V14RhoA geranylgeranylation was also required for suppressing p21(WAF) transcription, promoting cell cycle progression and cellular proliferation. The ability of V14RhoA to induce focus formation and enhance plating efficiency and oncogenic Ras anchorage-dependent growth was also dependent on its geranylgeranylation. The only biological activity of V14RhoA that was not dependent on its prenylation was its ability to induce serum response element transcriptional activity. Furthermore, we demonstrate that a farnesylated form of V14RhoA was also able to bind RhoGDI-1, was able to induce cytoskeleton organization, proliferation, and transformation, and was just as potent as geranylgeranylated V14RhoA at suppressing p21(WAF) transcriptional activity. These results demonstrate that RhoA geranylgeranylation is required for its biological activity and that the nature of the lipid modification is not critical.
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Affiliation(s)
- C Allal
- Oncologie Cellulaire et Moléculaire, EA 2048 Université Paul Sabatier, Centre de Lutte Contre le Cancer Claudius Regaud, 20-24 rue du Pont Saint-Pierre, 31052 Toulouse cedex, France
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20
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Detraves C, Mazarguil H, Lajoie-Mazenc I, Julian M, Raynaud-Messina B, Wright M. Protein complexes containing gamma-tubulin are present in mammalian brain microtubule protein preparations. Cell Motil Cytoskeleton 2000; 36:179-89. [PMID: 9015205 DOI: 10.1002/(sici)1097-0169(1997)36:2<179::aid-cm7>3.0.co;2-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The presence of gamma-tubulin in microtubule preparations, obtained by disassembly/ assembly cycles at 0degreesC/37degreesC from the brain of several mammals, is demonstrated by immunoblotting with specific antibodies directed against three distinct regions of the protein. In contrast gamma-tubulin was absent from pure tubulin obtained by chromatography on phosphocellulose, but was retained on the column with the other microtubule-associated proteins. A large part of the gamma-tubulin was present in cold stable material remaining after microtubule disassembly at OdegreesC and was partially solubilized using high salt, thus preventing its purification by the usual assembly/disassembly procedure used for alpha/beta-tubulin heterodimers. Brain gamma-tubulin was purified by affinity chromatography with gamma-tubulin antibodies raised against its carboxyl terminal region. Purified gamma-tubulin consisted of at least two polypeptides present in equal quantities and exhibiting a pI of 6.5 and 6.6, respectively. It was associated with the alpha/beta-tubulin heterodimer and with at least five other polypeptides of 75, 105, 130, 195, and 250 kDa. With the exception of the 250 kDa polypeptide, all of these proteins seem to be present in gamma-tubulin complexes isolated from Xenopus eggs. But, in contrast with Xenopus egg complexes, brain complexes exhibited a considerable heterogeneity of their apparent masses and composition in sucrose gradient centrifugation, in agreement with the absence of an homogeneous structure in electron microscopy. Despite this heterogeneity, gamma-tubulin complexes bind quantitatively to microtubule extremities. The possibility to further use mammalian brain gamma-tubulin and some of its associated proteins in biochemical and pharmacological experiments is of interest since brain microtubule protein preparations have been extensively used for studying both microtubule dynamics and the activity of microtubule poisons.
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Affiliation(s)
- C Detraves
- C.N.R.S., Institut de Pharmacologie et de Biologie Structurale, Toulouse, France
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21
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Vacaresse N, Lajoie-Mazenc I, Augé N, Suc I, Frisach MF, Salvayre R, Nègre-Salvayre A. Activation of epithelial growth factor receptor pathway by unsaturated fatty acids. Circ Res 1999; 85:892-9. [PMID: 10559135 DOI: 10.1161/01.res.85.10.892] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Nonesterified fatty acids (NEFAs) are acutely liberated during lipolysis and are chronically elevated in pathological conditions, such as insulin resistance, hypertension, and obesity, which are known risk factors for atherosclerosis. The purpose of this study was to investigate the effect and mechanism of action of NEFAs on the epithelial growth factor (EGF) receptor (EGFR). In the ECV-304 endothelial cell line, unsaturated fatty acids triggered a time- and dose-dependent tyrosine phosphorylation of EGFR (polyunsaturated fatty acids [PUFAs] were the most active), whereas saturated FAs were inactive. Although less potent than PUFAs, oleic acid (OA) was used because it is prominent in the South European diet and is only slightly oxidizable (thus excluding oxidation derivatives). EGFR is activated by OA independent of any autocrine secretion of EGF or other related mediators. OA-induced EGFR autophosphorylation triggered EGFR signaling pathway activation (as assessed through coimmunoprecipitation of SH2 proteins such as SHC, GRB2, and SHP-2) and subsequent p42/p44 mitogen-activated protein kinase (as shown by the use of EGFR- deficient B82L and EGFR- transduced B82LK(+) cell lines). OA induced in vitro both autophosphorylation and activation of intrinsic tyrosine kinase of immunopurified EGFR, thus suggesting that EGFR is a primary target of OA. EGFR was also activated by mild surfactants, Tween-20 and Triton X-100, both in vitro (on immunopurified EGFR) and in intact living cells, thus indicating that EGFR is sensitive to amphiphilic molecules. These data suggest that EGFR is activated by OA and PUFAs, acts as a sensor for unsaturated fatty acids (and amphiphilic molecules), and is a potential transducer by which diet composition may influence vascular wall biology.
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Affiliation(s)
- N Vacaresse
- INSERM U-466 and Department of Biochemistry, IFR-31, CHU Rangueil, Toulouse, France
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22
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Rotaru V, Lajoie-Mazenc I, Tollon Y, Raynaud-Messina B, Jean C, Détraves C, Julian M, Moisand A, Wright M. Condensation-decondensation of the gamma-tubulin containing material in the absence of a structurally visible organelle during the cell cycle of Physarum plasmodia. Biol Cell 1999; 91:393-406. [PMID: 10519002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Genetic evidence has shown the presence of a common spindle pole organiser in Physarum amoebae and plasmodia. But the typical centrosome and mitosis observed in amoebae are replaced in plasmodia by an intranuclear mitosis devoid of any structurally defined organelle. The fate of gamma-tubulin and of another component (TPH17) of the centrosome of Physarum amoebae was investigated in the nuclei of synchronous plasmodia. These two amoebal centrosomal elements were present in the nuclear compartment during the entire cell cycle and exhibited similar relocalisation from metaphase to telophase. Three preparation methods showed that gamma-tubulin containing material was dispersed in the nucleoplasm during interphase. It constituted an intranuclear thread-like structure. In contrast, the TPH17 epitope exhibited a localisation close to the nucleolus. In late G2-phase, the gamma-tubulin containing elements condensed in a single organelle which further divided. Intranuclear microtubules appeared before the condensation of the gamma-tubulin material and treatment with microtubule poisons suggested that microtubules were required in this process. The TPH17 epitope relocalised in the intranuclear spindle later than the gamma-tubulin containing material suggesting a maturation process of the mitotic poles. The decondensation of the gamma-tubulin material and of the material containing the TPH17 epitope occurred immediately after telophase. Hence in the absence of a structurally defined centrosome homologue, the microtubule nucleating material undergoes a cycle of condensation and decondensation during the cell cycle.
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Affiliation(s)
- V Rotaru
- Institut de Pharmacologie et Biologie Structurale, CNRS, Toulouse, France
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23
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Abstract
Oxidized low density lipoproteins (oxLDL) are thought to play a major role in atherosclerosis. OxLDL exhibit a wide variety of biological effects resulting from their ability to interfere with intracellular signaling. The cellular targets and primary signaling events of oxLDL are unknown. We report that oxLDL elicit, in intact cells, tyrosine phosphorylation of the epithelial growth factor receptor (EGFR) and activation of its signaling pathway. This activation triggered by oxLDL was associated with derivatization of reactive amino groups of EGFR and was mimicked by 4-hydroxynonenal (4-HNE, a major lipid peroxidation product of oxLDL). Immunopurified EGFR was derivatized and activated in vitro by oxLDL lipid extracts and 4-HNE, thus indicating that 1) EGFR may be a primary target of oxidized lipids and 2) EGFR derivatization may be associated with activation. The reported data suggest that EGFR acts as a sensor for oxidized lipids. We therefore propose a novel concept of the mechanism by which oxidized lipids (contained in oxLDL or more generally produced during oxidative stress) are able to activate receptor tyrosine kinase and subsequent signaling pathways, resulting finally in a gain of function.
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Affiliation(s)
- I Suc
- INSERM U-466 and Biochemistry Department, Institut Louis Bugnard, CHU Rangueil, Toulouse, France
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24
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Augé N, Escargueil-Blanc I, Lajoie-Mazenc I, Suc I, Andrieu-Abadie N, Pieraggi MT, Chatelut M, Thiers JC, Jaffrézou JP, Laurent G, Levade T, Nègre-Salvayre A, Salvayre R. Potential role for ceramide in mitogen-activated protein kinase activation and proliferation of vascular smooth muscle cells induced by oxidized low density lipoprotein. J Biol Chem 1998; 273:12893-900. [PMID: 9582320 DOI: 10.1074/jbc.273.21.12893] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.9] [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
Proliferation of vascular smooth muscle cells (SMC) is a hallmark in the pathogenesis of atherosclerotic lesions. Mildly oxidized low density lipoproteins (UV-oxLDL), which are mitogenic to cultured AG-08133A SMC, activate the sphingomyelin (SM)-ceramide pathway. We report here the following. (i) UV-oxLDL elicited a biphasic and sustained activation of MBP kinase activity, phosphorylation and nuclear translocation of p44/42 mitogen-activated protein kinase (MAPK), and [3H]thymidine incorporation, which were inhibited by PD-098059, a MAPK kinase inhibitor. (ii) The use of preconditioned media (from SMC pre-activated by UV-oxLDL) transferred to native SMC and blocking antibodies against growth factors suggest that UV-oxLDL-induced activation of MAPK and [3H]thymidine incorporation seem to be independent of any autocrine secretion of growth factors. (iii) UV-oxLDL-induced activation of a neutral sphingomyelinase, SM hydrolysis, ceramide production, and [3H]thymidine incorporation were inhibited by two serine-protease inhibitors (serpins), suggesting that a serpin-sensitive proteolytic pathway is involved in the activation of the SM-ceramide signaling pathway. (iv) UV-oxLDL-induced MAPK activation and [3H]thymidine incorporation were mimicked by ceramide generated in the plasma membrane by bacterial sphingomyelinase treatment or by addition of the permeant C2-ceramide. Serpins did not inhibit the MAPK activation and [3H]thymidine incorporation induced by C2-ceramide, indicating that activation of the MAPK and [3H]thymidine incorporation is subsequent to the stimulation of the SM-ceramide pathway. Taken together, these data suggest that mitogenic concentrations of UV-oxLDL are able to stimulate the SM-ceramide pathway through a protease-dependent mechanism and activate p44/42 MAPK, leading to proliferation of vascular SMC.
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Affiliation(s)
- N Augé
- Laboratory of Biochemistry, INSERM U-466, Institut Louis Bugnard, CHU Rangueil, 1 Avenue Jean Poulhes, 31403 Toulouse Cedex 4, France
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25
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Lajoie-Mazenc I, Détraves C, Rotaru V, Garès M, Tollon Y, Jean C, Julian M, Wright M, Raynaud-Messina B. A single gamma-tubulin gene and mRNA, but two gamma-tubulin polypeptides differing by their binding to the spindle pole organizing centres. J Cell Sci 1996; 109 ( Pt 10):2483-92. [PMID: 8923209 DOI: 10.1242/jcs.109.10.2483] [Citation(s) in RCA: 9] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Cells of eukaryotic organisms exhibit microtubules with various functions during the different developmental stages. The identification of multiple forms of alpha- and beta-tubulins had raised the question of their possible physiological roles. In the myxomycete Physarum polycephalum a complex polymorphism for alpha- and beta-tubulins has been correlated with a specific developmental expression pattern. Here, we have investigated the potential heterogeneity of gamma-tubulin in this organism. A single gene, with 3 introns and 4 exons, and a single mRNA coding for gamma-tubulin were detected. They coded for a polypeptide of 454 amino acids, with a predicted molecular mass of 50,674, which presented 64–76% identity with other gamma-tubulins. However, immunological studies identified two gamma-tubulin polypeptides, both present in the two developmental stages of the organism, uninucleate amoebae and multinucleate plasmodia. The two gamma-tubulins, called gamma s- and gamma f-tubulin for slow and fast electrophoretic mobility, exhibited apparent molecular masses of 52,000 and 50,000, respectively. They were recognized by two antibodies (R70 and JH46) raised against two distinct conserved sequences of gamma-tubulins. They were present both in the preparations of amoebal centrosomes possessing two centrioles and in the preparations of plasmodial nuclear metaphases devoid of structurally distinct polar structures. These two gamma-tubulins exhibited different sedimentation properties as shown by ultracentrifugation and sedimentation in sucrose gradients. Moreover, gamma s-tubulin was tightly bound to microtubule organizing centers (MTOCs) while gamma f-tubulin was loosely associated with these structures. This first demonstration of the presence of two gamma-tubulins with distinct properties in the same MTOC suggests a more complex physiological role than previously assumed.
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Affiliation(s)
- I Lajoie-Mazenc
- Institut de Pharmacologie et de Biologie Structurale (CNRS), Toulouse, France
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26
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Lajoie-Mazenc I, Tollon Y, Detraves C, Julian M, Moisand A, Gueth-Hallonet C, Debec A, Salles-Passador I, Puget A, Mazarguil H. Recruitment of antigenic gamma-tubulin during mitosis in animal cells: presence of gamma-tubulin in the mitotic spindle. J Cell Sci 1994; 107 ( Pt 10):2825-37. [PMID: 7876350 DOI: 10.1242/jcs.107.10.2825] [Citation(s) in RCA: 116] [Impact Index Per Article: 3.9] [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: 11/20/2022] Open
Abstract
It has been claimed repeatedly that gamma-tubulin is exclusively localized at the spindle poles in mitotic animal cells, where it plays a role in microtubule nucleation. In addition to this localization, we have observed a gamma-tubulin-specific staining of the mitotic spindle in several animal cells (human, kangaroo rat, mouse, Chinese hamster, Xenopus and Drosophila) using five polyclonal antibodies raised against unique gamma-tubulin sequences and four different fixation protocols. In HeLa and PtK2 cells, gamma-tubulin was detected in the mitotic spindle from late prometaphase to telophase. In contrast, in other cell types, it was detected in metaphase only. In all cases we failed to detect gamma-tubulin in the short aster microtubules at the spindle poles. Electron microscopic observation revealed that at least part of the gamma-tubulin localized on the surface of spindle microtubules with a preferential distribution along kinetochore microtubules. In HeLa cells, the amount of antigenic gamma-tubulin was fairly constant in the spindle poles during mitosis from prometaphase to telophase. In contrast, gamma-tubulin appeared in the mitotic spindles in prometaphase. The amount of gamma-tubulin decreased in telophase, where it relocalized in the interzone. In metaphase cells about 15–25% of the total fluorescence was localized at the spindle poles, while 75–85% of the fluorescence was distributed over the rest of the spindle. These results suggest that the localization and timing of gamma-tubulin during the cell cycle is highly regulated and that is physiological role could be more complex and diverse than initially assumed.
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Affiliation(s)
- I Lajoie-Mazenc
- Laboratoire de Pharmacologie et de Toxicologie Fondamentales CNRS, Toulouse, France
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Julian M, Tollon Y, Lajoie-Mazenc I, Moisand A, Mazarguil H, Puget A, Wright M. gamma-Tubulin participates in the formation of the midbody during cytokinesis in mammalian cells. J Cell Sci 1993; 105 ( Pt 1):145-56. [PMID: 8360269 DOI: 10.1242/jcs.105.1.145] [Citation(s) in RCA: 118] [Impact Index Per Article: 3.8] [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: 11/20/2022] Open
Abstract
Animal cells undergoing cytokinesis form an inter-cellular bridge containing two bundles of microtubules interdigitated at their plus ends, which constitute the midbody. Polyclonal antibodies raised against three specific amino acid sequences of gamma-tubulin (EEFATEGGDRKDV, NIIQGEADPTDVHKSL and EYHAATRPDYISWGTQEQ) specifically stained the centrosome in interphase, the spindle poles in all stages of mitosis, and the extremities of the midbody in mammalian cells (Potorous, human, Chinese hamster, mouse). This staining was prevented by the corresponding peptides, by Xenopus gamma-tubulin, but was not modified by purified alpha beta-tubulin heterodimer. An identical staining was obtained with affinity-purified antibodies against the carboxyl-terminal amino acid sequence of human gamma-tubulin. No gamma-tubulin could be detected in the interzone during anaphase and early telophase. Material containing gamma-tubulin first appeared in the two daughter cells on each side of the division plane in late telophase, and accumulated transiently at the minus ends of the two microtubule bundles constituting the midbody for one hour after metaphase. Micro-injection of gamma-tubulin antibodies into anaphase cells prevented the subsequent formation of the microtubule bundles between the two daughter cells. In contrast with previous views, these observations suggest that the microtubules constituting the midbody may be nucleated on special microtubule organizing centres, active during late telophase only, and assembled on each side of the dividing plane between the daughter cells.
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Affiliation(s)
- M Julian
- Laboratoire de Pharmacologie et de Toxicologie fondamentales, CNRS, Toulouse, France
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Gueth-Hallonet C, Antony C, Aghion J, Santa-Maria A, Lajoie-Mazenc I, Wright M, Maro B. gamma-Tubulin is present in acentriolar MTOCs during early mouse development. J Cell Sci 1993; 105 ( Pt 1):157-66. [PMID: 8360270 DOI: 10.1242/jcs.105.1.157] [Citation(s) in RCA: 161] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
gamma-Tubulin, a recently discovered member of the tubulin superfamily, is a peri-centriolar component considered to be essential for microtubule nucleation. Mouse oocytes and early embryos lack centrioles until the blastocyst stage. Thus, early mouse embryos allowed us to study the location of gamma-tubulin in animal cells in the absence of centrioles. For this, we used an antiserum directed against a specific peptide of the gamma-tubulin sequence, which is conserved among species. This serum has been characterised both in PtK2 and mouse cells. We found that it specifically-stained the spindle poles and the cytoplasmic microtubule organizing centers in metaphase II oocytes and the spindle poles in mitosis during the cleavage stages. In contrast, no interphase staining could be detected during cleavage. Since the overall level of gamma-tubulin did not decrease during interphase, as shown by immunoblotting experiments, this absence of staining during interphase is probably due to a cytoplasmic dispersion of gamma-tubulin. A single dot-like interphase reactivity appeared at the 32-cell stage. In parallel, electron microscopy studies allowed us to detect centrioles for the first time at the 64-cell stage. The possible roles of gamma-tubulin in microtubule nucleation and in centrosome maturation are discussed.
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Affiliation(s)
- C Gueth-Hallonet
- Département de Biologie du Développement, Institut Jacques Monod, CNRS-Université Paris VII, France
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