51
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Yuan J, Slice LW, Rozengurt E. Activation of protein kinase D by signaling through Rho and the alpha subunit of the heterotrimeric G protein G13. J Biol Chem 2001; 276:38619-27. [PMID: 11507098 DOI: 10.1074/jbc.m105530200] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Protein kinase D (PKD/PKCmu) immunoprecipitated from COS-7 cells transiently transfected with either a constitutively active mutant of Rho (RhoQ63L) or the Rho-specific guanine nucleotide exchange factor pOnco-Lbc (Lbc) exhibited a marked increase in basal activity. Addition of aluminum fluoride to cells co-transfected with PKD and wild type Galpha(13) also induced PKD activation. Co-transfection of Clostridium botulinum C3 toxin blocked activation of PKD by RhoQ63L, Lbc, or aluminum fluoride-stimulated Galpha(13). Treatment with the protein kinase C inhibitors GF I or Ro 31-8220 prevented the increase in PKD activity induced by RhoQ63L, Lbc, or aluminum fluoride-stimulated Galpha(13). PKD activation in response to Galpha(13) signaling was also completely prevented by mutation of Ser-744 and Ser-748 to Ala in the kinase activation loop of PKD. Co-expression of C. botulinum C3 toxin and a COOH-terminal fragment of Galpha(q) that acts in a dominant-negative fashion blocked PKD activation in response to agonist stimulation of bombesin receptor. Expression of the COOH-terminal region of Galpha(13) also attenuated PKD activation in response to bombesin receptor stimulation. Our results show that Galpha(13) contributes to PKD activation through a Rho- and protein kinase C-dependent signaling pathway and indicate that PKD activation is mediated by both Galpha(q) and Galpha(13) in response to bombesin receptor stimulation.
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Affiliation(s)
- J Yuan
- Department of Medicine, School of Medicine and Molecular Biology Institute, UCLA, Los Angeles, California 90095, USA
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52
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Charron F, Tsimiklis G, Arcand M, Robitaille L, Liang Q, Molkentin JD, Meloche S, Nemer M. Tissue-specific GATA factors are transcriptional effectors of the small GTPase RhoA. Genes Dev 2001; 15:2702-19. [PMID: 11641276 PMCID: PMC312821 DOI: 10.1101/gad.915701] [Citation(s) in RCA: 184] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Rho-like GTPases play a pivotal role in the orchestration of changes in the actin cytoskeleton in response to receptor stimulation, and have been implicated in transcriptional activation, cell growth regulation, and oncogenic transformation. Recently, a role for RhoA in the regulation of cardiac contractility and hypertrophic cardiomyocyte growth has been suggested but the mechanisms underlying RhoA function in the heart remain undefined. We now report that transcription factor GATA-4, a key regulator of cardiac genes, is a nuclear mediator of RhoA signaling and is involved in the control of sarcomere assembly in cardiomyocytes. Both RhoA and GATA-4 are essential for sarcomeric reorganization in response to hypertrophic growth stimuli and overexpression of either protein is sufficient to induce sarcomeric reorganization. Consistent with convergence of RhoA and GATA signaling, RhoA potentiates the transcriptional activity of GATA-4 via a p38 MAPK-dependent pathway that phosphorylates GATA-4 activation domains and GATA binding sites mediate RhoA activation of target cardiac promoters. Moreover, a dominant-negative GATA-4 protein abolishes RhoA-induced sarcomere reorganization. The identification of transcription factor GATA-4 as a RhoA mediator in sarcomere reorganization and cardiac gene regulation provides a link between RhoA effects on transcription and cell remodeling.
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Affiliation(s)
- F Charron
- Laboratoire de développement et différenciation cardiaques, Institut de recherches cliniques de Montréal (IRCM), Montréal, Québec, Canada H2W 1R7
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53
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Corre I, Gomez M, Vielkind S, Cantrell DA. Analysis of thymocyte development reveals that the GTPase RhoA is a positive regulator of T cell receptor responses in vivo. J Exp Med 2001; 194:903-14. [PMID: 11581313 PMCID: PMC2193481 DOI: 10.1084/jem.194.7.903] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Loss of function of the guanine nucleotide binding protein RhoA blocks pre-T cell differentiation and survival indicating that this GTPase is a critical signaling molecule during early thymocyte development. Previous work has shown that the Rho family GTPase Rac-1 can initiate changes in actin dynamics necessary and sufficient for pre-T cell development. The present data now show that Rac-1 actions in pre-T cells require Rho function but that RhoA cannot substitute for Rac-1 and induce the actin cytoskeletal changes necessary for pre-T cell development. Activation of Rho is thus not sufficient to induce pre-T cell differentiation or survival in the absence of the pre-T cell receptor (TCR). The failure of RhoA activation to impact on pre-TCR-mediated signaling was in marked contrast to its actions on T cell responses mediated by the mature TCR alpha/beta complex. Cells expressing active RhoA were thus hyperresponsive in the context of TCR-induced proliferation in vitro and in vivo showed augmented positive selection of thymocytes expressing defined TCR complexes. This reveals that RhoA function is not only important for pre-T cells but also plays a role in determining the fate of mature T cells.
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Affiliation(s)
- Isabelle Corre
- Lymphocyte Activation Laboratory, Imperial Cancer Research Fund, London, WC2A 3PX, UK
| | - Manuel Gomez
- Lymphocyte Activation Laboratory, Imperial Cancer Research Fund, London, WC2A 3PX, UK
| | - Susina Vielkind
- Lymphocyte Activation Laboratory, Imperial Cancer Research Fund, London, WC2A 3PX, UK
| | - Doreen A. Cantrell
- Lymphocyte Activation Laboratory, Imperial Cancer Research Fund, London, WC2A 3PX, UK
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54
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Aznar S, Lacal JC. Searching new targets for anticancer drug design: the families of Ras and Rho GTPases and their effectors. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 2001; 67:193-234. [PMID: 11525383 DOI: 10.1016/s0079-6603(01)67029-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The Ras superfamily of low-molecular-weight GTPases are proteins that, in response to diverse stimuli, control key cellular processes such as cell growth and development, apoptosis, lipid metabolism, cytoarchitecture, membrane trafficking, and transcriptional regulation. More than 100 genes of this superfamily grouped in six subfamilies have been described so far, pointing to the complexities and specificities of their cellular functions. Dysregulation of members of at least two of these families (the Ras and the Rho families) is involved in the events that lead to the uncontrolled proliferation and invasiveness of human tumors. In recent years, the cloning and characterization of downstream effectors for Ras and Rho proteins have given crucial clues to the specific pathways that lead to aberrant cellular growth and ultimately to tumorigenesis. A direct link between the functions of some of these effectors with the appearance of transformed cells and their ability to proliferate and invade surrounding tissues has been made. Accordingly, drugs that specifically alter their functions display antineoplasic properties, and some of these drugs are already under clinical trials. In this review, we survey the progress made in understanding the underlying molecular connections between carcinogenesis and the specific cellular functions elicited by some of these effectors. We also discuss new drugs with antineoplastic or antimetastatic activity that are targeted to specific effectors for Ras or Rho proteins.
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Affiliation(s)
- S Aznar
- Instituto de Investigaciones Biomédicas, CSIC, Madrid, Spain
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55
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Takeda K, Ichiki T, Tokunou T, Iino N, Fujii S, Kitabatake A, Shimokawa H, Takeshita A. Critical role of Rho-kinase and MEK/ERK pathways for angiotensin II-induced plasminogen activator inhibitor type-1 gene expression. Arterioscler Thromb Vasc Biol 2001; 21:868-73. [PMID: 11348889 DOI: 10.1161/01.atv.21.5.868] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Plasminogen activator inhibitor type-1 (PAI-1) plays an integral role not only in the regulation of fibrinolytic activity but also in the pathogenesis of atherosclerosis and hypertension. We investigated the signaling pathways of angiotensin II (Ang II) leading to PAI-1 gene expression. Ang II increased the PAI-1 mRNA and protein levels in a time- and dose-dependent manner through the Ang II type 1 receptor in vascular smooth muscle cells. PAI-1 gene promoter activity measured by luciferase assay was significantly increased by Ang II. PAI-1 mRNA stability was also increased by Ang II. Ang II-induced PAI-1 mRNA upregulation was inhibited by BAPTA-AM, genistein, and AG1478, suggesting that intracellular calcium, tyrosine kinase, and epidermal growth factor receptor transactivation are involved. Furthermore, PD98059, an inhibitor of extracellular signal-regulated kinase (ERK) kinase (MEK), almost completely suppressed Ang II-induced PAI-1 upregulation. Adenovirus-mediated overexpression of the dominant-negative form of Rho-kinase or Y27632, a Rho-kinase inhibitor, also completely prevented PAI-1 induction by Ang II without affecting Ang II-induced ERK activation. These data suggest that activation of MEK/ERK and Rho-kinase pathways plays a pivotal role in PAI-1 gene upregulation by Ang II. The Rho-kinase pathway may be a novel target to inhibit Ang II signaling, and its inhibition may be useful in the treatment of hypertension as well as atherosclerosis.
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Affiliation(s)
- K Takeda
- Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
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56
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Li W, Whaley CD, Bonnevier JL, Mondino A, Martin ME, Aagaard-Tillery KM, Mueller DL. CD28 signaling augments Elk-1-dependent transcription at the c-fos gene during antigen stimulation. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 167:827-35. [PMID: 11441089 DOI: 10.4049/jimmunol.167.2.827] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Untransformed CD4(+) Th1 cells stimulated with Ag and APC demonstrated a dependence on B7- and CD28-mediated costimulatory signals for the expression and function of AP-1 proteins. The induction of transactivation by the c-fos gene regulator Elk-1 mirrored this requirement for TCR and CD28 signal integration. c-Jun N-terminal kinase (JNK) (but not extracellular signal-regulated kinase or p38) protein kinase activity was similarly inhibited by neutralizing anti-B7 mAbs. Blockade of JNK protein kinase activity with SB 202190 prevented both Elk-1 transactivation and c-Fos induction. These results identify a unique role for B7 costimulatory molecules and CD28 in the activation of JNK during Ag stimulation in Th1 cells, and suggest that JNK regulates Elk-1 transactivation at the c-fos gene to promote the formation of AP-1 complexes important to IL-2 gene expression.
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Affiliation(s)
- W Li
- Department of Medicine, Rheumatic and Autoimmune Diseases Section, and Center for Immunology, University of Minnesota Medical School, Minneapolis, MN 55455, USA
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57
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Gower TL, Peeples ME, Collins PL, Graham BS. RhoA is activated during respiratory syncytial virus infection. Virology 2001; 283:188-96. [PMID: 11336544 DOI: 10.1006/viro.2001.0891] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Respiratory syncytial virus (RSV) is an important human pathogen that can cause severe and life-threatening respiratory infections in infants and immunocompromised adults. We have recently shown the RSV F glycoprotein, which mediates viral fusion and entry, interacts with the cellular protein RhoA in two-hybrid and in vitro binding assays. Whether this interaction occurs in living cells remains an open question. However, because RhoA signaling is associated with many cellular functions relevant to RSV pathogenesis such as actin cytoskeleton organization, expression of proinflammatory cytokines, and smooth muscle contraction, we asked whether RhoA activation occurred during RSV infection of HEp-2 cells. We found that the amount of isoprenylated and membrane-bound RhoA in RSV-infected cultures was increased. Further evidence of RhoA activation was demonstrated by downstream signaling activity mediated by RhoA. There was an increase in p130(cas) phosphorylation during RSV infection, which was prevented by Y-27632, a specific inhibitor of Rho kinase, or lovastatin, an HMG-CoA reductase inhibitor that reduces the synthesis of groups needed for isoprenylation. In addition, RSV infection of HEp-2 cells resulted in an increase in the formation of actin stress fibers. Pretreatment of HEp-2 cells with Clostridium botulinum C3 exotoxin, an enzyme that specifically ADP-ribosylates and inactivates RhoA, prevented RSV-induced stress fiber formation. These observations indicate that RhoA and subsequent downstream signaling events are activated during RSV infection, which has implications for RSV pathogenesis.
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Affiliation(s)
- T L Gower
- Department of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
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58
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Abstract
rhoB encoding a Ras-related GTPase is immediate-early inducible by genotoxic treatments, indicating that it is part of the cellular stress response. Here, we investigated the influence of RhoB on signal pathways that are rapidly evoked by genotoxic compounds. The data obtained show that wild-type RhoB neither affects activation of mitogen-activated protein kinases nor AP-1-dependent gene expression. However, RhoB inhibited both basal and genotoxic agent-stimulated activity of the transcription factor nuclear factor kappaB (NF-kappaB). Thus, RhoB attenuated alkylation-induced increase in the DNA binding activity of NF-kappaB and abrogated NF-kappaB-driven gene expression. Furthermore, RhoB inhibited decrease in the cellular amount of IkappaBalpha after genotoxic stress as well as after tumor necrosis factor alpha and 12-O-tetradecanoylphorbol acetate treatment. This indicates that RhoB represses NF-kappaB activation by inhibiting dissociation and subsequent degradation of IkappaBalpha. On the basis of the data, we suggest that RhoB is a novel negative regulator of NF-kappaB signaling.
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Affiliation(s)
- G Fritz
- Division of Applied Toxicology, Institute of Toxicology, University of Mainz, D-55131 Mainz, Germany.
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59
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Medley QG, Serra-Pagès C, Iannotti E, Seipel K, Tang M, O'Brien SP, Streuli M. The trio guanine nucleotide exchange factor is a RhoA target. Binding of RhoA to the trio immunoglobulin-like domain. J Biol Chem 2000; 275:36116-23. [PMID: 10948190 DOI: 10.1074/jbc.m003775200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Trio is a complex protein containing two guanine nucleotide exchange factor domains each with associated pleckstrin homology domains, a serine/threonine kinase domain, two SH3 domains, an immunoglobulin-like domain, and spectrin-like repeats. Trio was originally identified as a LAR tyrosine phosphatase-binding protein and is involved in actin remodeling, cell migration, and cell growth. Herein we provide evidence that Trio not only activates RhoA but is also a RhoA target. The RhoA-binding site was mapped to the Trio immunoglobulin-like domain. RhoA isoprenylation is necessary for the RhoA-Trio interaction, because mutation of the RhoA carboxyl-terminal cysteine residue blocked binding. The existence of an intramolecular functional link between RhoA activation and RhoA binding is suggested by the finding that Trio exchange activity enhanced RhoA binding to Trio. Furthermore, immunofluorescence studies of HeLa cells showed that although ectopically expressed Trio was evenly distributed within the cell, co-expression of Trio with RhoA resulted in relocalization of Trio into punctate structures. Relocalization was not observed with Trio constructs lacking the immunoglobulin-like domain, indicating that RhoA acts to regulate Trio localization via binding to the immunoglobulin-like domain. We propose that Trio-mediated RhoA activation and subsequent RhoA-mediated relocalization of Trio functions to modulate and coordinate Trio signaling.
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Affiliation(s)
- Q G Medley
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA
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60
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Johnston IM, Spence HJ, Winnie JN, McGarry L, Vass JK, Meagher L, Stapleton G, Ozanne BW. Regulation of a multigenic invasion programme by the transcription factor, AP-1: re-expression of a down-regulated gene, TSC-36, inhibits invasion. Oncogene 2000; 19:5348-58. [PMID: 11103936 DOI: 10.1038/sj.onc.1203927] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The transcription factor AP-1 (activator protein-1) is required for transformation by many oncogenes, which function upstream of it in the growth factor-ras signal transduction pathway. Previously, we proposed that one role of AP-1 in transformation is to regulate the expression of a multigenic invasion programme. As a test of this proposal we sought to identify AP-1 regulated genes based upon their differential expression in 208F rat fibroblasts transformed by FBR-v-fos (FBR), and to determine if they functioned in the invasion programme. Subtracted cDNA libraries specific for up- or down-regulated genes in FBRs compared to 208Fs were constructed and analysed. Northern analysis revealed that the cDNAs in both libraries represented differentially expressed genes. Nucleic acid sequence analysis of randomly selected cDNA clones from each library coupled with searches of nucleic acid and amino acid sequence databases determined that many of the cDNAs represented proteins that function in various aspects of the invasion process. Functional analysis of one the down-regulated genes, TSC-36/follistatin-related protein (TSC-36/Frp), which has not previously been associated with invasion, demonstrated that its expression in FBRs inhibited in vitro invasion. These results support the proposal that AP-1 in transformed cells regulates a multigenic invasion programme.
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Affiliation(s)
- I M Johnston
- Beatson Institute for Cancer Research, CRC Beatson Laboratories, Bearsden, Glasgow
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61
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Pratt JC, Igras VE, Maeda H, Baksh S, Gelfand EW, Burakoff SJ, Neel BG, Gu H. Cutting edge: gab2 mediates an inhibitory phosphatidylinositol 3'-kinase pathway in T cell antigen receptor signaling. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 165:4158-63. [PMID: 11035047 DOI: 10.4049/jimmunol.165.8.4158] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Phosphatidylinositol 3'-kinase (PI3K) is a key component of multiple signaling pathways, where it typically promotes survival, proliferation, and/or adhesion. Here, we show that in TCR signaling, the scaffolding adapter Gab2 delivers an inhibitory signal via PI3K. Overexpression of Gab2 in T cell lines inhibits TCR-evoked activation of the IL-2 promoter, blocking NF-AT- and NF-kappaB-directed transcription. Inhibition is abrogated by mutating the Gab2 p85-binding sites, by treatment with PI3K inhibitors or by cotransfection of phosphatase homolog of tensin. Our findings provide the first evidence of a negative function for a scaffolding adapter in T cells and identify Gab2/PI3K-containing complexes as novel regulators of TCR signaling.
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Affiliation(s)
- J C Pratt
- Division of Cell Biology, Department of Pediatrics, National Jewish Medical and Research Center, Denver, CO 80206, USA
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62
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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] [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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63
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Hausding M, Witteck A, Rodriguez-Pascual F, von Eichel-Streiber C, Förstermann U, Kleinert H. Inhibition of small G proteins of the rho family by statins or clostridium difficile toxin B enhances cytokine-mediated induction of NO synthase II. Br J Pharmacol 2000; 131:553-61. [PMID: 11015307 PMCID: PMC1572362 DOI: 10.1038/sj.bjp.0703607] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
In order to investigate the involvement of Ras and/or Rho proteins in the induction of the inducible isoform of nitric oxide synthase (NOS II) we used HMG-CoA reductase inhibitors (statins) and Clostridium difficile toxin B (TcdB) as pharmacological tools. Statins indirectly inhibit small G proteins by preventing their essential farnesylation (Ras) and/or geranylgeranylation (Rho). In contrast, TcdB is a glucosyltransferase and inactivates Rho-proteins directly. Human A549/8- and DLD-1 cells as well as murine 3T3 fibroblasts were preincubated for 18 h with statins (1 - 100 microM) or TcdB (0.01-10 ng ml(-1)). Then NOS II expression was induced by cytokines. NOS II mRNA was measured after 4 - 8 h by RNase protection assay, and NO production were measured by the Griess assay after 24 h. Statins and TcdB markedly increased cytokine-induced NOS II mRNA expression and NO production. Statin-mediated enhancement of NOS II mRNA expression was reversed almost completely by cotreatment with mevalonate or geranylgeranylpyrophosphate. It was only slightly reduced by farnesylpyrophosphate. Therefore, small G proteins of the Rho family are likely to be involved in NOS II induction. In A549/8 cells stably transfected with a luciferase reporter gene under the control of a 16 kb fragment of the human NOS II promoter (pNOS2(16)Luc), statins produced only a small increase in cytokine-induced NOS II promoter activity. In contrast, statins had a considerable superinducing effect in DLD-1 cells stably transfected with pNOS2(16)Luc. In conclusion, our studies provide evidence that statins and TcdB potentiate cytokine-induced NOS II expression via inhibition of small G proteins of the Rho family. This in turn results in an enhanced NOS II promoter activity and/or a prolonged NOS II mRNA stability.
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Affiliation(s)
- Michael Hausding
- Department of Pharmacology, Johannes Gutenberg University, Obere Zahlbacher Strasse 67, D-55101 Mainz, Germany
| | - Andrea Witteck
- Department of Pharmacology, Johannes Gutenberg University, Obere Zahlbacher Strasse 67, D-55101 Mainz, Germany
| | - Fernando Rodriguez-Pascual
- Department of Pharmacology, Johannes Gutenberg University, Obere Zahlbacher Strasse 67, D-55101 Mainz, Germany
| | | | - Ulrich Förstermann
- Department of Pharmacology, Johannes Gutenberg University, Obere Zahlbacher Strasse 67, D-55101 Mainz, Germany
| | - Hartmut Kleinert
- Department of Pharmacology, Johannes Gutenberg University, Obere Zahlbacher Strasse 67, D-55101 Mainz, Germany
- Author for correspondence:
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64
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Sah VP, Seasholtz TM, Sagi SA, Brown JH. The role of Rho in G protein-coupled receptor signal transduction. Annu Rev Pharmacol Toxicol 2000; 40:459-89. [PMID: 10836144 DOI: 10.1146/annurev.pharmtox.40.1.459] [Citation(s) in RCA: 278] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Low molecular weight G proteins of the Rho subfamily are regulators of actin cytoskeletal organization. In contrast to the heterotrimeric G proteins, the small GTPases are not directly activated through ligand binding to G protein-coupled receptors (GPCRs). However, a subset of GPCRs, including those for lysophosphatidic acid and thrombin, induce stress fibers, focal adhesions, and cell rounding through Rho-dependent pathways. C3 exoenzyme has been a useful tool for demonstrating Rho involvement in these and other responses, including Ca2+ sensitization of smooth muscle contraction, cell migration, transformation, and serum response element-mediated gene expression. Most of the GPCRs that induce Rho-dependent responses can activate Gq, but this is not a sufficient signal. Recent data demonstrate that G alpha 12/13 can induce Rho-dependent responses. Furthermore, G alpha 12/13 can bind and activate Rho-specific guanine nucleotide exchange factors, providing a mechanism by which GPCRs that couple to G alpha 12/13 could activate Rho and its downstream responses.
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Affiliation(s)
- V P Sah
- Department of Pharmacology, University of California, San Diego 92093-0636, USA.
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65
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Billadeau DD, Mackie SM, Schoon RA, Leibson PJ. The Rho family guanine nucleotide exchange factor Vav-2 regulates the development of cell-mediated cytotoxicity. J Exp Med 2000; 192:381-92. [PMID: 10934226 PMCID: PMC2193212 DOI: 10.1084/jem.192.3.381] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2000] [Accepted: 05/23/2000] [Indexed: 11/04/2022] Open
Abstract
Previous pharmacologic and genetic studies have demonstrated a critical role for the low molecular weight GTP-binding protein RhoA in the regulation of cell-mediated killing by cytotoxic lymphocytes. However, a specific Rho family guanine nucleotide exchange factor (GEF) that activates this critical regulator of cellular cytotoxicity has not been identified. In this study, we provide evidence that the Rho family GEF, Vav-2, is present in cytotoxic lymphocytes, and becomes tyrosine phosphorylated after the cross-linking of activating receptors on cytotoxic lymphocytes and during the generation of cell-mediated killing. In addition, we show that overexpression of Vav-2 in cytotoxic lymphocytes enhances cellular cytotoxicity, and this enhancement requires a functional Dbl homology and Src homology 2 domain. Interestingly, the pleckstrin homology domain of Vav-2 was found to be required for enhancement of killing through some, but not all activating receptors on cytotoxic lymphocytes. Lastly, although Vav and Vav-2 share significant structural homology, only Vav is able to enhance nuclear factor of activated T cells-activator protein 1-mediated gene transcription downstream of the T cell receptor. These data demonstrate that Vav-2, a Rho family GEF, differs from Vav in the control of certain lymphocyte functions and participates in the control of cell-mediated killing by cytotoxic lymphocytes.
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Affiliation(s)
- Daniel D. Billadeau
- Department of Immunology, Mayo Graduate and Medical Schools, Mayo Clinic, Rochester, Minnesota 55905
| | - Stacy M. Mackie
- Department of Immunology, Mayo Graduate and Medical Schools, Mayo Clinic, Rochester, Minnesota 55905
| | - Renee A. Schoon
- Department of Immunology, Mayo Graduate and Medical Schools, Mayo Clinic, Rochester, Minnesota 55905
| | - Paul J. Leibson
- Department of Immunology, Mayo Graduate and Medical Schools, Mayo Clinic, Rochester, Minnesota 55905
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66
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Subbaramaiah K, Hart JC, Norton L, Dannenberg AJ. Microtubule-interfering agents stimulate the transcription of cyclooxygenase-2. Evidence for involvement of ERK1/2 AND p38 mitogen-activated protein kinase pathways. J Biol Chem 2000; 275:14838-45. [PMID: 10809726 DOI: 10.1074/jbc.275.20.14838] [Citation(s) in RCA: 237] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
We investigated whether microtubule-interfering agents (MIAs: taxol, colchicine, nocodazole, vinblastine, vincristine, 17-beta-estradiol, 2-methoxyestradiol) altered cyclooxygenase-2 (COX-2) expression in human mammary epithelial cells. MIAs enhanced prostaglandin E(2) synthesis and increased levels of COX-2 protein and mRNA. Nuclear run-off assays revealed increased rates of COX-2 transcription after treatment with MIAs. Calphostin C, an inhibitor of protein kinase C, blocked the induction of COX-2 by MIAs. The stimulation of COX-2 promoter activity by MIAs was inhibited by overexpressing dominant negative forms of Rho and Raf-1. MIAs stimulated ERK, JNK, and p38 mitogen-activated protein kinases (MAPK); pharmacological inhibitors of MAPK kinase and p38 MAPK blocked the induction of COX-2 by MIAs. Overexpressing dominant negative forms of ERK1 or p38 MAPK inhibited MIA-mediated activation of the COX-2 promoter. MIAs stimulated the binding of the activator protein-1 transcription factor complex to the cyclic AMP response element in the COX-2 promoter. A dominant negative form of c-Jun inhibited the activation of the COX-2 promoter by MIAs. Additionally, cytochalasin D, an agent that inhibits actin polymerization, stimulated COX-2 transcription by the same signaling pathway as MIAs. Thus, microtubule- or actin-interfering agents stimulated MAPK signaling and activator protein-1 activity. This led, in turn, to induction of COX-2 gene expression via the cyclic AMP response element site in the COX-2 promoter.
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Affiliation(s)
- K Subbaramaiah
- Department of Medicine, New York Presbyterian Hospital-Cornell and Strang Cancer Prevention Center, New York, New York 10021, USA.
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67
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Coghlan MP, Chou MM, Carpenter CL. Atypical protein kinases Clambda and -zeta associate with the GTP-binding protein Cdc42 and mediate stress fiber loss. Mol Cell Biol 2000; 20:2880-9. [PMID: 10733591 PMCID: PMC85517 DOI: 10.1128/mcb.20.8.2880-2889.2000] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Both the Rho family of low-molecular-weight GTP-binding proteins and protein kinases C (PKCs) mediate responses to a variety of extracellular and intracellular signals. They share many downstream targets, including remodeling of the actin cytoskeleton, activation of p70(S6) kinase and c-jun N-terminal kinase (JNK), and regulation of transcription and cell proliferation. We therefore investigated whether Rho family GTP-binding proteins bind to PKCs. We found that Cdc42 associates with atypical PKCs (aPKCs) PKCzeta and -lambda in a GTP-dependent manner. The regulatory domain of the aPKCs mediates the interaction. Expression of activated Cdc42 results in the translocation of PKClambda from the nucleus into the cytosol, and Cdc42 and PKClambda colocalize at the plasma membrane and in the cytoplasm. Expression of activated Cdc42 leads to a loss of stress fibers, as does overexpression of either the wild type or an activated form of PKClambda. Kinase-dead PKClambda and -zeta constructs acted as dominant negatives and restored stress fibers in cells expressing the activated V12 Cdc42 mutant, indicating that Cdc42-dependent loss of stress fibers requires aPKCs. Kinase-dead PKClambda and -zeta and dominant-negative N17 Cdc42 also blocked Ras-induced loss of stress fibers, suggesting that this pathway may also be important for Ras-dependent cytoskeletal changes. N17 Rac did not block Ras-induced loss of stress fibers, nor did kinase-dead PKClambda block V12 Rac-stimulated loss of stress fibers. These results indicate that Cdc42 and Rac use different pathways to regulate stress fibers.
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Affiliation(s)
- M P Coghlan
- Division of Signal Transduction, Beth Israel Deaconess Medical Center and Department of Medicine, Harvard Medical School, Boston, Massachusetts 02215, USA
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68
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Affiliation(s)
- X R Bustelo
- Department of Pathology, State University of New York at Stony Brook, Stony Brook, New York 11794, USA.
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69
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Inoue SB, Qadota H, Arisawa M, Watanabe T, Ohya Y. Prenylation of Rho1p is required for activation of yeast 1, 3-beta-glucan synthase. J Biol Chem 1999; 274:38119-24. [PMID: 10608882 DOI: 10.1074/jbc.274.53.38119] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
One of the essential protein substrates of geranylgeranyl transferase type I in the budding yeast Saccharomyces cerevisiae is a rho-type GTPase, Rho1p, which is a regulatory subunit of 1, 3-beta-glucan synthase. Previous studies have indicated that modification of Rho1p is significantly reduced in a mutant of the beta subunit of geranylgeranyl transferase type I called cal1-1. Here we present genetic and biochemical evidence showing that modification of Rho1p is required for activity of 1,3-beta-glucan synthase. The 1,3-beta-glucan synthase activity of the cal1-1 membrane was significantly reduced compared with that of the wild-type membrane. The impaired activity was partly due to the reduced amount of Fks1p, a putative catalytic subunit of 1, 3-beta-glucan synthase, but also partly due to reduced affinity between unmodified Rho1p and Fks1p. Glutathione S-transferase (GST)-Rho1 proteins with or without the C-terminal motif required for the modification were purified and used to analyze the interaction. The modified form of GST-Rho1p was specifically able to restore the 1,3-beta-glucan synthase of the rho1-3 membrane. Gel overlay analysis indicated that an unmodified form of GST-Rho1p fails to interact with Fks1p. These results indicated that the geranylgeranylation of Rho1p is a prerequisite to the assembly and activation of 1,3-beta-glucan synthase in vitro. Increased cytoplasmic levels of divalent cations such as Ca(2+) restored both Rho1p modification and the 1,3-beta-glucan synthase activity of cal1-1, suggesting that cytoplasmic levels of the divalent cations affect geranylgeranyl transferase type I activity in vivo.
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Affiliation(s)
- S B Inoue
- Department of Mycology, Nippon Roche Research Center, 200 Kajiwara, Kamakura, Kanagawa 247-8530, Japan
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70
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Angkachatchai V, Finkel TH. ADP-Ribosylation of Rho by C3 Ribosyltransferase Inhibits IL-2 Production and Sustained Calcium Influx in Activated T Cells. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.7.3819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Abstract
Activation of the T lymphocyte induces dramatic cytoskeletal changes, and there is increasing evidence that disruption of the cytoskeleton inhibits early and late events of T cell signal transduction. However, relatively little is known about the signaling molecules involved in activation-induced cytoskeletal rearrangement. The rho family of small GTP-binding proteins, which include rho, rac, and cdc42, regulates the cytoskeleton and coordinates various cellular functions via their many effector targets. In prior studies, the Clostridium botulinum toxin C3 exoenzyme has been used to ADP-ribosylate and inactivate rho. In this study, we demonstrate that treatment of T cells with C3 exoenzyme inhibits IL-2 transcription following ligation of the TCR. Inhibition of IL-2 expression correlated with loss of sustained increase in [Ca+2]i and mitogen activated protein kinase (MAPK/Erk) activity, but not with activation of the tyrosine kinase, lck. These findings are the first to show that ADP-ribosylation of rho by C3 ribosyltransferase (exoenzyme) inhibits IL-2 production due, in part, to the requirement for sustained calcium influx and MAPK activation after Ag receptor ligation.
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Affiliation(s)
- Vachras Angkachatchai
- *Division of Basic Sciences, Department of Pediatrics, National Jewish Medical and Research Center, Denver, CO 80206; and
| | - Terri H. Finkel
- *Division of Basic Sciences, Department of Pediatrics, National Jewish Medical and Research Center, Denver, CO 80206; and
- †Departments of Immunology, Pediatrics, and Biochemistry and Molecular Genetics, University of Colorado Health Sciences Center, Denver, CO 80262
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Tang J, Sawasdikosol S, Chang JH, Burakoff SJ. SLAP, a dimeric adapter protein, plays a functional role in T cell receptor signaling. Proc Natl Acad Sci U S A 1999; 96:9775-80. [PMID: 10449770 PMCID: PMC22286 DOI: 10.1073/pnas.96.17.9775] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Engagement of the T cell antigen receptor (TCR) leads to rapid activation of protein tyrosine kinases, which in turn phosphorylate downstream enzymes and adapter proteins. Some adapter proteins, such as SLP-76, Vav, and LAT, positively regulate TCR-mediated signal transduction, whereas others, such as Cbl, play an inhibitory role. SLAP (Src-like adapter protein), an adapter protein containing a Src homology 3 and a Src homology 2 domain, was isolated from a yeast interacting screen by using N-terminal Cbl as bait. N-terminal Cbl interacts with SLAP in vivo and in vitro in a tyrosine phosphorylation-independent manner. We observed that SLAP is expressed in T cells, and upon TCR activation, SLAP interacts with ZAP-70, Syk, LAT, and TCRzeta chain in Jurkat T cells. In transiently transfected COS-7 cells, SLAP forms separate complexes with ZAP-70, Syk, and LAT through its Src homology 2 domain. Overexpression of a C-terminal-truncated SLAP mutant down-regulates nuclear factor of activated T cells-AP1 activity. We have evidence that SLAP forms homodimers through its C-terminal region. Serial truncations and mutations in the C terminus of SLAP demonstrate that there is a correlation between the loss of dimerization and the inhibition of nuclear factor of activated T cells-AP1 activity. The in vivo association of SLAP with key signaling molecules and its inhibition of T cell activation suggests that SLAP plays an important role in TCR-mediated signal transduction.
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Affiliation(s)
- J Tang
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Department of Pediatrics, Harvard Medical School, 44 Binney Street, Boston, MA 02115, USA
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72
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Houssa B, de Widt J, Kranenburg O, Moolenaar WH, van Blitterswijk WJ. Diacylglycerol kinase theta binds to and is negatively regulated by active RhoA. J Biol Chem 1999; 274:6820-2. [PMID: 10066731 DOI: 10.1074/jbc.274.11.6820] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Diacylglycerol kinase (DGK) phosphorylates the second messenger diacylglycerol to yield phosphatidic acid. To date, very little is known about the regulation of DGK activity. We have previously identified the DGKtheta isotype, which is predominantly expressed in brain (Houssa, B., Schaap, D., van der Wal, J., Goto, K., Kondo, H., Yamakawa, A., Shibata, M., Takenawa, T., and Van Blitterswijk, W. J. (1997) J. Biol. Chem. 272, 10422-10428). We now report that DGKtheta binds specifically to activated RhoA in transfected COS cells as well as in nontransfected neuronal N1E-115 cells. Binding is abolished by a point mutation (Y34N) in the effector loop of RhoA. DGKtheta does not bind to inactive RhoA, nor to the other Rho-family GTPases, Rac or Cdc42. Like active RhoA, DGKtheta localizes to the plasma membrane. Strikingly, the binding of activated RhoA to DGKtheta completely inhibits DGK catalytic activity. Our results suggest that DGKtheta is a downstream effector of RhoA and that its activity is negatively regulated by RhoA. Through accumulation of newly produced diacylglycerol, RhoA-mediated inhibition of DGKtheta may lead to enhanced PKC activity in response to external stimuli.
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Affiliation(s)
- B Houssa
- Division of Cellular Biochemistry, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
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