1
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Rustandi RR, Hamm M. Development of an ADP-ribosylation assay for residual toxicity in C. difficile binary toxin CDTa using automated capillary western blot. J Pharm Biomed Anal 2020; 182:113125. [DOI: 10.1016/j.jpba.2020.113125] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 01/16/2020] [Accepted: 01/22/2020] [Indexed: 01/05/2023]
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2
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Raya-Sandino A, Castillo-Kauil A, Domínguez-Calderón A, Alarcón L, Flores-Benitez D, Cuellar-Perez F, López-Bayghen B, Chávez-Munguía B, Vázquez-Prado J, González-Mariscal L. Zonula occludens-2 regulates Rho proteins activity and the development of epithelial cytoarchitecture and barrier function. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:1714-1733. [PMID: 28554775 DOI: 10.1016/j.bbamcr.2017.05.016] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 05/18/2017] [Accepted: 05/24/2017] [Indexed: 12/11/2022]
Abstract
Silencing Zonula occludens 2 (ZO-2), a tight junctions (TJ) scaffold protein, in epithelial cells (MDCK ZO-2 KD) triggers: 1) Decreased cell to substratum attachment, accompanied by reduced expression of claudin-7 and integrin β1, and increased vinculin recruitment to focal adhesions and stress fibers formation; 2) Lowered cell-cell aggregation and appearance of wider intercellular spaces; 3) Increased RhoA/ROCK activity, mediated by GEF-HI recruitment to cell borders by cingulin; 4) Increased Cdc42 activity, mitotic spindle disorientation and the appearance of cysts with multiple lumens; 5) Increased Rac and cofilin activity, multiple lamellipodia formation and random cell migration but increased wound closure; 6) Diminished cingulin phosphorylation and disappearance of planar network of microtubules at the TJ region; and 7) Increased transepithelial electrical resistance at steady state, coupled to an increased expression of ZO-1 and claudin-4 and a decreased expression of claudin-2 and paracingulin. Hence, ZO-2 is a crucial regulator of Rho proteins activity and the development of epithelial cytoarchitecture and barrier function.
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Affiliation(s)
- Arturo Raya-Sandino
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (Cinvestav), México D.F. 07360, Mexico
| | - Alejandro Castillo-Kauil
- Department of Cell Biology, Center for Research and Advanced Studies (Cinvestav), México D.F. 07360, Mexico
| | - Alaide Domínguez-Calderón
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (Cinvestav), México D.F. 07360, Mexico
| | - Lourdes Alarcón
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (Cinvestav), México D.F. 07360, Mexico
| | - David Flores-Benitez
- Max-Planck-Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Francisco Cuellar-Perez
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (Cinvestav), México D.F. 07360, Mexico
| | - Bruno López-Bayghen
- Department of Toxicology, Center for Research and Advanced Studies (Cinvestav), México D.F. 07360, Mexico
| | - Bibiana Chávez-Munguía
- Department of Infectomics and Molecular Pathogenesis, Center for Research and Advanced Studies (Cinvestav), México D.F. 07360, Mexico
| | - José Vázquez-Prado
- Department of Pharmacology, Center for Research and Advanced Studies (Cinvestav), México D.F. 07360, Mexico
| | - Lorenza González-Mariscal
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (Cinvestav), México D.F. 07360, Mexico.
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3
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Qiu W, Steinberg SF. Phos-tag SDS-PAGE resolves agonist- and isoform-specific activation patterns for PKD2 and PKD3 in cardiomyocytes and cardiac fibroblasts. J Mol Cell Cardiol 2016; 99:14-22. [PMID: 27515283 DOI: 10.1016/j.yjmcc.2016.08.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 08/05/2016] [Accepted: 08/06/2016] [Indexed: 01/16/2023]
Abstract
Protein kinase D (PKD) consists of a family of three structurally related enzymes that are co-expressed in the heart and have important roles in many biological responses. PKD1 is activated by pro-hypertrophic stimuli and has been implicated in adverse cardiac remodeling. Efforts to define the cardiac actions of PKD2 and PKD3 have been less successful at least in part because conventional methods provide a general screen for PKD activation but are poorly suited to resolve activation patterns for PKD2 or PKD3. This study uses Phos-tag SDS-PAGE, a method that exaggerates phosphorylation-dependent mobility shifts, to overcome this technical limitation. Phos-tag SDS-PAGE resolves PKD1 as distinct molecular species (indicative of pools of enzyme with distinct phosphorylation profiles) in unstimulated cardiac fibroblasts and cardiomyocytes; as a result, attempts to track PKD1 mobility shifts that result from agonist activation were only moderately successful. In contrast, PKD2 and PKD3 are recovered from resting cardiac fibroblasts and cardiomyocytes as single molecular species; both enzymes display robust mobility shifts in Phos-tag SDS-PAGE in response to treatment with sphingosine-1-phosphate, thrombin, PDGF, or H2O2. Studies with GF109203X implicate protein kinase C activity in the stimulus-dependent pathways that activate PKD2/PKD3 in both cardiac fibroblasts and cardiomyocytes. Studies with C3 toxin identify a novel role for Rho in the sphingosine-1-phosphate and thrombin receptor-dependent pathways that lead to the phosphorylation of PKD2/3 and the downstream substrate CREB in cardiomyocytes. In conclusion, Phos-tag SDS-PAGE provides a general screen for stimulus-specific changes in PKD2 and PKD3 phosphorylation and exposes a novel role for these enzymes in specific stress-dependent pathways that influence cardiac remodeling.
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Affiliation(s)
- Weihua Qiu
- Department of Pharmacology, Columbia University, New York, NY 10032, United States
| | - Susan F Steinberg
- Department of Pharmacology, Columbia University, New York, NY 10032, United States.
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4
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Zhao X, Ding EY, Yu OM, Xiang SY, Tan-Sah VP, Yung BS, Hedgpeth J, Neubig RR, Lau LF, Brown JH, Miyamoto S. Induction of the matricellular protein CCN1 through RhoA and MRTF-A contributes to ischemic cardioprotection. J Mol Cell Cardiol 2014; 75:152-61. [PMID: 25106095 PMCID: PMC4157956 DOI: 10.1016/j.yjmcc.2014.07.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 07/07/2014] [Accepted: 07/23/2014] [Indexed: 01/06/2023]
Abstract
Activation of RhoA, a low molecular-weight G-protein, plays an important role in protecting the heart against ischemic stress. Studies using non-cardiac cells demonstrate that the expression and subsequent secretion of the matricellular protein CCN1 is induced by GPCR agonists that activate RhoA. In this study we determined whether and how CCN1 is induced by GPCR agonists in cardiomyocytes and examined the role of CCN1 in ischemic cardioprotection in cardiomyocytes and the isolated perfused heart. In neonatal rat ventricular myocytes (NRVMs), sphingosine 1-phosphate (S1P), lysophosphatidic acid (LPA) and endothelin-1 induced robust increases in CCN1 expression while phenylephrine, isoproterenol and carbachol had little or no effect. The ability of agonists to activate the small G-protein RhoA correlated with their ability to induce CCN1. CCN1 induction by S1P was blocked when RhoA function was inhibited with C3 exoenzyme or a pharmacological RhoA inhibitor. Conversely overexpression of RhoA was sufficient to induce CCN1 expression. To delineate the signals downstream of RhoA we tested the role of MRTF-A (MKL1), a co-activator of SRF, in S1P-mediated CCN1 expression. S1P increased the nuclear accumulation of MRTF-A and this was inhibited by the functional inactivation of RhoA. In addition, pharmacological inhibitors of MRTF-A or knockdown of MRTF-A significantly diminished S1P-mediated CCN1 expression, indicating a requirement for RhoA/MRTF-A signaling. We also present data indicating that CCN1 is secreted following agonist treatment and RhoA activation, and binds to cells where it can serve an autocrine function. To determine the functional significance of CCN1 expression and signaling, simulated ischemia/reperfusion (sI/R)-induced apoptosis was assessed in NRVMs. The ability of S1P to protect against sI/R was significantly reduced by the inhibition of RhoA, ROCK or MRTF-A or by CCN1 knockdown. We also demonstrate that ischemia/reperfusion induces CCN1 expression in the isolated perfused heart and that this functions as a cardioprotective mechanism, evidenced by the significant increase in infarct development in response to I/R in the cardiac specific CCN1 KO relative to control mice. Our findings implicate CCN1 as a mediator of cardioprotection induced by GPCR agonists that activate RhoA/MRTF-A signaling.
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Affiliation(s)
- Xia Zhao
- Department of Pharmacology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0636, USA
| | - Eric Y Ding
- Department of Pharmacology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0636, USA
| | - Olivia M Yu
- Department of Pharmacology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0636, USA
| | - Sunny Y Xiang
- Department of Pharmacology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0636, USA
| | - Valerie P Tan-Sah
- Department of Pharmacology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0636, USA
| | - Bryan S Yung
- Department of Pharmacology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0636, USA
| | - Joe Hedgpeth
- CompleGen, Inc., 1124 Columbia Street, Seattle, WA 98104, USA
| | - Richard R Neubig
- Department of Pharmacology and Toxicology, Michigan State University, 1355 Bogue St./B440 Life Sciences, East Lansing, MI 48824, USA
| | - Lester F Lau
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, College of Medicine, 900 S Ashland, Chicago, IL 60607, USA
| | - Joan Heller Brown
- Department of Pharmacology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0636, USA
| | - Shigeki Miyamoto
- Department of Pharmacology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0636, USA.
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5
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Wang S, Li H, Chen Y, Wei H, Gao GF, Liu H, Huang S, Chen JL. Transport of influenza virus neuraminidase (NA) to host cell surface is regulated by ARHGAP21 and Cdc42 proteins. J Biol Chem 2012; 287:9804-9816. [PMID: 22318733 DOI: 10.1074/jbc.m111.312959] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Influenza virus neuraminidase (NA) is transported to the virus assembly site at the plasma membrane and is a major viral envelope component that plays a critical role in the release of progeny virions and in determination of host range restriction. However, little is known about the host factors that are involved in regulating the intracellular and cell surface transport of NA. Here we identified the Cdc42-specific GAP, ARHGAP21 differentially expressed in host cells infected with influenza A virus using cDNA microarray analysis. Furthermore, we have investigated the involvement of Rho family GTPases in NA transport to the cell surface. We found that expression of constitutively active or inactive mutants of RhoA or Rac1 did not significantly affect the amount of NA that reached the cell surface. However, expression of constitutively active Cdc42 or depletion of ARHGAP21 promoted the transport of NA to the plasma membranes. By contrast, cells expressing shRNA targeting Cdc42 or overexpressing ARHGAP21 exhibited a significant decrease in the amount of cell surface-localized NA. Importantly, silencing Cdc42 reduced influenza A virus replication, whereas silencing ARHGAP21 increased the virus replication. Together, our results reveal that ARHGAP21- and Cdc42-based signaling regulates the NA transport and thereby impacts virus replication.
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Affiliation(s)
- Song Wang
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences (CAS), Beijing 100101, China
| | - Hua Li
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences (CAS), Beijing 100101, China,; College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China, and
| | - Yuhai Chen
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences (CAS), Beijing 100101, China
| | - Haitao Wei
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences (CAS), Beijing 100101, China
| | - George F Gao
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences (CAS), Beijing 100101, China
| | - Hongqiang Liu
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences (CAS), Beijing 100101, China
| | - Shile Huang
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130
| | - Ji-Long Chen
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences (CAS), Beijing 100101, China,.
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6
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Dovas A, Choi Y, Yoneda A, Multhaupt HAB, Kwon SH, Kang D, Oh ES, Couchman JR. Serine 34 phosphorylation of rho guanine dissociation inhibitor (RhoGDIalpha) links signaling from conventional protein kinase C to RhoGTPase in cell adhesion. J Biol Chem 2010; 285:23296-308. [PMID: 20472934 PMCID: PMC2906322 DOI: 10.1074/jbc.m109.098129] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Conventional protein kinase C (PKC) isoforms are essential serine/threonine kinases regulating many signaling networks. At cell adhesion sites, PKCα can impact the actin cytoskeleton through its influence on RhoGTPases, but the intermediate steps are not well known. One important regulator of RhoGTPase function is the multifunctional guanine nucleotide dissociation inhibitor RhoGDIα that sequesters several related RhoGTPases in an inactive form, but it may also target them through interactions with actin-associated proteins. Here, it is demonstrated that conventional PKC phosphorylates RhoGDIα on serine 34, resulting in a specific decrease in affinity for RhoA but not Rac1 or Cdc42. The mechanism of RhoGDIα phosphorylation is distinct, requiring the kinase and phosphatidylinositol 4,5-bisphosphate, consistent with recent evidence that the inositide can activate, localize, and orient PKCα in membranes. Phosphospecific antibodies reveal endogenous phosphorylation in several cell types that is sensitive to adhesion events triggered, for example, by hepatocyte growth factor. Phosphorylation is also sensitive to PKC inhibition. Together with fluorescence resonance energy transfer microscopy sensing GTP-RhoA levels, the data reveal a common pathway in cell adhesion linking two essential mediators, conventional PKC and RhoA.
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Affiliation(s)
- Athanassios Dovas
- Division of Biomedical Sciences, Faculty of Medicine, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
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7
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Extracellular signal-regulated kinase promotes Rho-dependent focal adhesion formation by suppressing p190A RhoGAP. Mol Cell Biol 2010; 30:3233-48. [PMID: 20439493 DOI: 10.1128/mcb.01178-09] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Cell migration is critical for normal development and for pathological processes including cancer cell metastasis. Dynamic remodeling of focal adhesions and the actin cytoskeleton are crucial determinants of cell motility. The Rho family and the mitogen-activated protein kinase (MAPK) module consisting of MEK-extracellular signal-regulated kinase (ERK) are important regulators of these processes, but mechanisms for the integration of these signals during spreading and motility are incompletely understood. Here we show that ERK activity is required for fibronectin-stimulated Rho-GTP loading, Rho-kinase function, and the maturation of focal adhesions in spreading cells. We identify p190A RhoGAP as a major target for ERK signaling in adhesion assembly and identify roles for ERK phosphorylation of the C terminus in p190A localization and activity. These observations reveal a novel role for ERK signaling in adhesion assembly in addition to its established role in adhesion disassembly.
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8
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RATTAN SATISH, PHILLIPS BENJAMINR, MAXWELL PINCKNEYJ. RhoA/Rho-kinase: pathophysiologic and therapeutic implications in gastrointestinal smooth muscle tone and relaxation. Gastroenterology 2010; 138:13-8.e1-3. [PMID: 19931260 PMCID: PMC5599165 DOI: 10.1053/j.gastro.2009.11.016] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- SATISH RATTAN
- Department of Medicine, Division of Gastroenterology & Hepatology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA
| | - BENJAMIN R. PHILLIPS
- Department of Surgery, Division of Colon and Rectal Surgery, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA
| | - PINCKNEY J. MAXWELL
- Department of Surgery, Division of Colon and Rectal Surgery, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA
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9
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Abstract
Over the last decade, the Rho family GTPases have gained considerable recognition as powerful regulators of actin cytoskeletal organization. As with many high profile signal transducers, these molecules soon attracted the attention of the cardiovascular research community. Shortly thereafter, two prominent members known as RhoA and Rac1 were linked to agonist-induced gene expression and myofilament organization using the isolated cardiomyocyte cell model. Subsequent creation of transgenic mouse lines provided evidence for more complex roles of RhoA and Rac1 signaling. Clues from in vitro and in vivo studies suggest the involvement of numerous downstream targets of RhoA and Rac1 signaling including serum response factor, NF-kappaB, and other transcription factors, myofilament proteins, ion channels, and reactive oxygen species generation. Which of these contribute to the observed phenotypic effects of enhanced RhoA and Rac activation in vivo remain to be determined. Current research efforts with a more translational focus have used statins or Rho kinase blockers to assess RhoA and Rac1 as targets for interventional approaches to blunt hypertrophy or heart failure. Generally, salutary effects on remodeling and ischemic damage are observed, but the broad specificity and multiple cellular targets for these drugs within the myocardium demands caution in interpretation. In this review, we assess the evolution of knowledge related to Rac1 and RhoA in the context of hypertrophy and heart failure and highlight the direction that future exploration will lead.
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Affiliation(s)
- Joan Heller Brown
- Department of Pharmacology, University of California, San Diego, USA
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10
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Haug G, Barth H, Aktories K. Purification and Activity of the Rho ADP‐Ribosylating Binary C2/C3 Toxin. Methods Enzymol 2006; 406:117-27. [PMID: 16472654 DOI: 10.1016/s0076-6879(06)06010-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
C3 exoenzyme from Clostridium limosum, specifically ADP-ribosylates and inactivates Rho GTPases, but not or much less than Rac and Cdc42. To bypass the poor cell accessibility of the exoenzyme, a chimeric fusion toxin was constructed consisting of C3 exoenzyme and the N-terminal adaptor domain of the enzyme component C2I of the actin-ADP-ribosylating Clostridium botulinum C2 toxin. This fusion toxin C2IN-C3 is transported into cells by interaction with the binding and translocation component (C2II) of C2 toxin. Purification and activity of the chimeric toxin is reported.
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Affiliation(s)
- Gerd Haug
- Albert Ludwigs Universitat Freiburg, Institut fur Experimentelle & Klinische Pharmakologie & Toxikologie, Germany
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11
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Vielkind S, Gallagher-Gambarelli M, Gomez M, Hinton HJ, Cantrell DA. Integrin regulation by RhoA in thymocytes. THE JOURNAL OF IMMUNOLOGY 2005; 175:350-7. [PMID: 15972668 DOI: 10.4049/jimmunol.175.1.350] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The guanine nucleotide-binding protein Rho has essential functions in T cell development and is important for the survival and proliferation of T cell progenitors in the thymus. To explore the mechanisms used by RhoA to control thymocyte biology, the role of this GTPase in the regulation of integrin-mediated cell adhesion was examined. The data show that RhoA activation is sufficient to stimulate beta(1) and beta(2) integrin-mediated adhesion in murine thymocytes. RhoA is also needed for integrin activation in vivo as loss of Rho function impaired the ability of thymocytes to adhere to the extracellular matrix protein VCAM-1 and prevented integrin activation induced by the GTPases Rac-1 and Rap1A in vivo. The regulated activity of integrins is needed for cell motility and in the present study it was seen that RhoA activity is critical for integrin-mediated thymocyte migration to chemokines in vitro. Thus, RhoA has a critical role in regulating cell adhesion and migration during T cell development.
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Affiliation(s)
- Susina Vielkind
- Lymphocyte Activation Laboratory, Cancer Research U.K. London Research Institute, Lincoln's Inn Fields Laboratories, London, United Kingdom
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12
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Pang H, Guo Z, Su W, Xie Z, Eto M, Gong MC. RhoA-Rho kinase pathway mediates thrombin- and U-46619-induced phosphorylation of a myosin phosphatase inhibitor, CPI-17, in vascular smooth muscle cells. Am J Physiol Cell Physiol 2005; 289:C352-60. [PMID: 15814590 DOI: 10.1152/ajpcell.00111.2005] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Protein kinase C-potentiated phosphatase inhibitor of 17 kDa (CPI-17) mediates some agonist-induced smooth muscle contraction by suppressing the myosin phosphatase in a phosphorylation-dependent manner. The physiologically relevant kinases that phosphorylate CPI-17 remain to be identified. Several previous studies have shown that some agonist-induced CPI-17 phosphorylation in smooth muscle tissues was attenuated by the Rho kinase (ROCK) inhibitor Y-27632, suggesting that ROCK is involved in agonist-induced CPI-17 phosphorylation. However, Y-27632 has recently been found to inhibit protein kinase C (PKC)-delta, a well-recognized CPI-17 kinase. Thus the role of ROCK in agonist-induced CPI-17 phosphorylation remains uncertain. The present study was designed to address this important issue. We selectively activated the RhoA pathway using inducible adenovirus-mediated expression of a constitutively active mutant RhoA (V14RhoA) in primary cultured rabbit aortic vascular smooth muscle cells (VSMCs). V14RhoA caused expression level-dependent CPI-17 phosphorylation at Thr38 as well as myosin phosphatase phosphorylation at Thr853. Importantly, we have shown that V14RhoA-induced CPI-17 phosphorylation was not affected by the PKC inhibitor GF109203X but was abolished by Y-27632, suggesting that ROCK but not PKC was involved. Furthermore, we have shown that the contractile agonists thrombin and U-46619 induced CPI-17 phosphorylation in VSMCs. Similarly to V14RhoA-induced CPI-17 phosphorylation, thrombin-induced CPI-17 phosphorylation was not affected by inhibition of PKC with GF109203X, but it was blocked by inhibition of RhoA with adenovirus-mediated expression of exoenzyme C3 as well as by Y-27632. Taken together, our present data provide the first clear evidence indicating that ROCK is responsible for thrombin- and U-46619-induced CPI-17 phosphorylation in primary cultured VSMCs.
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Affiliation(s)
- Huan Pang
- Department of Physiology and Graduate Center for Nutritional Sciences, University of Kentucky, Lexington, KY 40536, USA
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13
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Kim JS, Diebold BA, Kim JI, Kim J, Lee JY, Park JB. Rho is involved in superoxide formation during phagocytosis of opsonized zymosans. J Biol Chem 2004; 279:21589-97. [PMID: 14970220 DOI: 10.1074/jbc.m308386200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Phagocytosis is accompanied by the production of superoxide by the NADPH oxidase complex, for which GTP-bound Rac is essential. We wanted to determine whether Rho is also involved in the production of superoxide during phagocytosis. Inhibition of Rho by Tat-C3 exoenzyme (Tat-C3) blocked superoxide formation and curtailed the phagocytosis of serum- (SOZ), C3bi- (COZ), and IgG-opsonized zymosan (IOZ) particles. Tat-C3 did not affect superoxide formation in response to phorbol myristate acetate (PMA), formyl Met-Leu-Phe (fMLP), or macrophage colony-stimulating factor (M-CSF). Superoxide formation was also reduced in J774 cells transfected with a cDNA expressing dominant-negative form of RhoA (N19RhoA). However, purified prenylated recombinant RhoA did not activate NADPH oxidase in vitro, suggesting that Rho does not interact directly with NADPH oxidase. Tat-C3 inhibited the activity of RhoA, but did not affect that of Rac in vitro or in vivo. It also inhibited the phosphorylation of p47(PHOX), one of the cytosolic components of NADPH oxidase. Taken together, these results suggest that Rho plays an important role in superoxide formation during phagocytosis of SOZ, COZ, and IOZ via phosphorylation of p47(PHOX).
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Affiliation(s)
- Jun-Sub Kim
- Department of Biochemistry, College of Medicine, Hallym University, Chunchon, Kangwon-Do 200-702, South Korea
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14
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Rattan S, Puri RN, Fan YP. Involvement of rho and rho-associated kinase in sphincteric smooth muscle contraction by angiotensin II. Exp Biol Med (Maywood) 2003; 228:972-81. [PMID: 12968070 DOI: 10.1177/153537020322800814] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The tonic smooth muscles of lower esophageal sphincter (LES) and internal anal sphincter (IAS) are subject to modulation by the neurohumoral agents. We report that angiotensin (Ang) II-induced contraction of rat IAS and LES smooth muscle cells (SMC) was inhibited by Clostridium botulinum C3 exozyme, HA 1077 and Y 27632, suggesting a role for Rho kinase and a Rho-associated kinase (ROK). Ang II-induced contraction of the SMC was also attenuated by genistein, antibodies to the pp60(c-src), p(190) RhoGTPase-activating protein (p190 RhoGAP), carboxyl terminus of Galpha13, carboxyl terminus peptide, and ADP ribosylation factor (ARF) antibody. Ang II-induced increase in p(190) RhoGAP tyrosine phosphorylation was attenuated by genistein. Furthermore, Ang II-induced increase in smooth muscle tone and phosphorylation of myosin light chain (MLC; 20 kDa; MLC20-P) were attenuated by Y 27632 and genistein. The results suggest an important role for Galpha13 and pp60(c-src) in the intracellular events responsible for the activation of RhoA/ROK in Ang II-induced contraction of LES and IAS SMC.
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Affiliation(s)
- Satish Rattan
- Department of Medicine, Division of Gastroenterology and Hepatology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
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15
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Wilde C, Barth H, Sehr P, Han L, Schmidt M, Just I, Aktories K. Interaction of the Rho-ADP-ribosylating C3 exoenzyme with RalA. J Biol Chem 2002; 277:14771-6. [PMID: 11847234 DOI: 10.1074/jbc.m201072200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
RhoA, -B, and -C are ADP-ribosylated and biologically inactivated by Clostridium botulinum C3 exoenzyme and related C3-like transferases. We report that RalA GTPase, which is not ADP-ribosylated by C3, inhibits ADP-ribosylation of RhoA by C3 from C. botulinum (C3bot), Clostridium limosum (C3lim), and Bacillus cereus (C3cer) but not from Staphylococcus aureus (C3stau) in human platelet membranes and rat brain lysate. Inhibition by RalA occurs with the GDP- and guanosine 5'-3-O-(thio)triphosphate-bound forms of RalA and is overcome by increasing concentrations of C3. A direct interaction of RalA with C3 was verified by precipitation of the transferase with GST-RalA-Sepharose. The affinity constant (K(d)) of the binding of RalA to C3lim was 12 nm as determined by fluorescence titration. RalA increased the NAD glycohydrolase activity of C3bot by about 5-fold. Although RalA had no effect on glucosylation of Rho GTPases by Clostridium difficile toxin B, C3bot and C3lim inhibited glucosylation of RalA by Clostridium sordellii lethal toxin. Furthermore, C3bot decreased activation of phospholipase D by RalA. The data indicate that several C3 exoenzymes directly interact with RalA without ADP-ribosylating the GTPase. The interaction is of high affinity and interferes with essential functions of C3 and RalA.
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Affiliation(s)
- Christian Wilde
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie der Albert-Ludwigs-Universität Freiburg, Otto-Krayer-Haus, Albertstrasse 25, D-79104 Freiburg, Germany
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16
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Panaretou C, Tooze SA. Regulation and recruitment of phosphatidylinositol 4-kinase on immature secretory granules is independent of ADP-ribosylation factor 1. Biochem J 2002; 363:289-95. [PMID: 11931656 PMCID: PMC1222477 DOI: 10.1042/0264-6021:3630289] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Heterotrimeric G-proteins, as well as small GTPases of the Rho and ADP-ribosylation factor (ARF) family, are implicated in the regulation of lipid kinases, including PtdIns 4-kinases and PtdIns(4)P 5-kinases. Here, we describe a PtdIns 4-kinase activity on immature secretory granules (ISGs), regulated secretory organelles formed from the trans-Golgi network (TGN), and investigate the regulation of PtdIns4P levels on these membranes. Over 50% of the PtdIns 4-kinase activity on ISGs is inhibited by both a low concentration of adenosine and the monoclonal antibody 4C5G, a specific inhibitor of the type II PtdIns 4-kinase. Treatment of ISGs with mastoparan 7 (M7) stimulates the type II PtdIns 4-kinase via pertussis-toxin-sensitive G(i)/G(0) proteins, which, in contrast with previous results obtained with chromaffin granules [Gasman, Chasserot-Golaz, Hubert, Aunis and Bader (1998) J. Biol. Chem. 273, 16913-16920], does not require Rho A, B or C. M7 treatment also leads to an inhibition in the recruitment of ARF to ISG membranes: this inhibition is not dependent on G(i)/G(0) activation, and is not linked to the stimulation of PtdIns 4-kinase observed with M7. PtdIns 4-kinase activity on ISGs is not regulated by myristoylated ARF1-GTP, in contrast with results obtained with Golgi membranes [Godi, Pertile, Meyers, Marra, Di Tullio, Iurisci, Luini, Corda and De Matteis (1999) Nat. Cell Biol. 1, 280-287; Jones, Morris, Morgan, Kondo, Irvine and Cockcroft (2000) J. Biol. Chem. 275, 13962-13170], whereas ARF1-GTP does regulate the production of PtdIns(4,5)P(2). Our results suggest that the regulation of PtdIns 4-kinase on the ISGs differs in comparison with that on the TGN, and might be related to a specific requirement of ISG maturation.
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Affiliation(s)
- Christina Panaretou
- The Secretory Pathways Laboratory, Cancer Research UK London Institute, 44 Lincoln's Inn Fields, London WC2A 3PX, U.K
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17
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Liberto M, Cobrinik D, Minden A. Rho regulates p21(CIP1), cyclin D1, and checkpoint control in mammary epithelial cells. Oncogene 2002; 21:1590-9. [PMID: 11896588 DOI: 10.1038/sj.onc.1205242] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2001] [Revised: 11/30/2001] [Accepted: 12/06/2001] [Indexed: 11/08/2022]
Abstract
The small GTPase Rho is important for cell cycle progression and Ras transformation in fibroblasts. However, it is unclear whether Rho is needed for proliferation in other cell types, and its targets in promoting normal cell cycle progression are unknown. Here, we demonstrate that Rho is required for G1 to S progression in MCF10A mammary epithelial cells, both in response to EGF and in response to oncogenic Ras. We describe two effects of Rho, the repression of p21(CIP1) and the induction of cyclin D1, that may underlie its role in promoting S phase entry. The Rho inhibitor, C3 exotransferase, induced p21(CIP1) both in EGF-stimulated and V12Ras-expressing cells. In addition, C3 blocked EGF-stimulated cyclin D1 promoter activity whereas V14RhoA induced the cyclin D1 promoter and cooperated with V12Ras in cyclin D1 induction. Finally, a high proportion of cells co-expressing V14RhoA and V12Ras displayed lobulated, polyploid nuclei that were actively synthesizing DNA. Our results demonstrate that Rho plays a fundamental role in promoting Ras-dependent S phase entry in mammary epithelial cells, whether in response to normal or oncogenic signaling, and indicate that in cells expressing oncogenic Ras, the activation of Rho diminishes p21(CIP1) expression, increases cyclin D1 promoter activity, and uncouples DNA synthesis from mitosis.
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Affiliation(s)
- Muriel Liberto
- Columbia University, Biological Sciences MC 2460, Sherman Fairchild Center, Room 813, 1212 Amsterdam Avenue, New York, NY 10027, USA
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18
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Barth H, Roebling R, Fritz M, Aktories K. The binary Clostridium botulinum C2 toxin as a protein delivery system: identification of the minimal protein region necessary for interaction of toxin components. J Biol Chem 2002; 277:5074-81. [PMID: 11741886 DOI: 10.1074/jbc.m109167200] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The binary Clostridium botulinum C2 toxin is composed of the enzyme component C2I and the binding component C2II, which are individual and non-linked proteins. Activated C2IIa mediates cell binding and translocation of C2I into the cytoplasm. C2I ADP-ribosylates G-actin at Arg-177 to depolymerize actin filaments. A fusion toxin containing the N-terminal domain of C2I (residues 1-225) transports C3 ADP-ribosyltransferase from Clostridium limosum into cells (Barth, H., Hofmann, F., Olenik, C., Just, I., and Aktories, K. (1998) Infect. Immun. 66, 1364-1369). We characterized the adaptor function of C2I and its interaction with C2IIa. The fusion toxin GST-C2I(1-225)-C3 was efficiently transported by C2IIa, indicating that C2IIa translocates proteins into the cytosol even when the C2I(1-225) adaptor was positioned in the middle of a fusion protein. Amino acid residues 1-87 of C2I were sufficient for interaction with C2IIa and for translocation of C2I fusion toxins into HeLa cells. Residues 1-87 were the minimal part of C2I to bind to C2IIa on the cell surface, as detected by fluorescence-activated cytometry. An excess of C2I(1-87) (but not of further truncated C2I fragments) competed with Alexa488-labeled C2I for binding to C2IIa. Also, the fragment C2I(30-431) and the fusion toxin C2I(30-225)-C3 competed with C2I-Alexa488 for binding to C2IIa. C2I(30-225)-C3 did not induce cytotoxic effects on cells when applied together with C2IIa, indicating that amino acid residues 1-29 are involved in translocation of C2I but are not absolutely essential for binding to C2IIa.
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Affiliation(s)
- Holger Barth
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie der Albert-Ludwigs-Universität Freiburg, Albertstrasse 25, D-79104 Freiburg Germany.
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19
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Sakr SW, Eddy RJ, Barth H, Wang F, Greenberg S, Maxfield FR, Tabas I. The uptake and degradation of matrix-bound lipoproteins by macrophages require an intact actin Cytoskeleton, Rho family GTPases, and myosin ATPase activity. J Biol Chem 2001; 276:37649-58. [PMID: 11477084 DOI: 10.1074/jbc.m105129200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A key cellular event in atherogenesis is the interaction of macrophages with lipoproteins in the subendothelium. In vivo, these lipoproteins are bound to matrix and often aggregated, yet most cell-culture experiments explore these events using soluble monomeric lipoproteins. We hypothesized that the internalization and degradation of matrix-retained and aggregated low density lipoprotein (LDL) by macrophages may involve the actin-myosin cytoskeleton in a manner that distinguishes this process from the endocytosis of soluble LDL. To explore these ideas, we plated macrophages on sphingomyelinase-aggregated LDL bound to smooth muscle cell-derived matrix in the presence of lipoprotein lipase. The macrophages internalized and degraded the LDL, which was mediated partially by the LDL receptor-related protein. Cytochalasin D and latrunculin A, which block actin polymerization, markedly inhibited the uptake and degradation of matrix-retained LDL but not soluble LDL. Inhibition of Rho family GTPases by Clostridium difficile toxin B blocked the degradation of matrix-retained and aggregated LDL by >90% without any inhibition of soluble LDL degradation. However, specific inhibition of Rho had no effect, suggesting the importance of Rac1 and Cdc42. Degradation of matrix-retained, but not soluble, LDL was also blocked by inhibitors of tyrosine kinase, phosphatidylinositol 3-kinase, and myosin ATPase. These findings define fundamental cytoskeletal pathways that may be involved in macrophage foam cell formation in vivo but have been missed by the use of previous cell culture models.
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Affiliation(s)
- S W Sakr
- Department of Medicine, Columbia University, New York, New York 10032, USA
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20
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Latham VM, Yu EH, Tullio AN, Adelstein RS, Singer RH. A Rho-dependent signaling pathway operating through myosin localizes beta-actin mRNA in fibroblasts. Curr Biol 2001; 11:1010-6. [PMID: 11470405 DOI: 10.1016/s0960-9822(01)00291-3] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND The sorting of mRNA is a determinant of cell asymmetry. The cellular signals that direct specific RNA sequences to a particular cellular compartment are unknown. In fibroblasts, beta-actin mRNA has been shown to be localized toward the leading edge, where it plays a role in cell motility and asymmetry. RESULTS We demonstrate that a signaling pathway initiated by extracellular receptors acting through Rho GTPase and Rho-kinase regulates this spatial aspect of gene expression in fibroblasts by localizing beta-actin mRNA via actomyosin interactions. Consistent with the role of Rho as an activator of myosin, we found that inhibition of myosin ATPase, myosin light chain kinase (MLCK), and the knockout of myosin II-B in mouse embryonic fibroblasts all inhibited beta-actin mRNA from localizing in response to growth factors. CONCLUSIONS We therefore conclude that the sorting of beta-actin mRNA in fibroblasts requires a Rho mediated pathway operating through a myosin II-B-dependent step and postulate that polarized actin bundles direct the mRNA to the leading edge of the cell.
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Affiliation(s)
- V M Latham
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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21
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Wicki A, Niggli V. The Rho/Rho-kinase and the phosphatidylinositol 3-kinase pathways are essential for spontaneous locomotion of Walker 256 carcinosarcoma cells. Int J Cancer 2001; 91:763-71. [PMID: 11275977 DOI: 10.1002/1097-0215(200102)9999:9999<::aid-ijc1128>3.0.co;2-b] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Signal transduction pathways controlling spontaneous locomotion of Walker carcinosarcoma cells are not well understood. We have therefore investigated the role of signalling proteins in development of polarity and locomotion of these cells. Treatment of the cells with 100 ng/ml pertussis toxin had no significant effect on the percentage of polarized cells. In contrast, 2 different phosphatidylinositol 3-kinase inhibitors (wortmannin and LY-294002) markedly reduced the proportion of polarized cells. Spontaneous locomotion of the cells was also significantly inhibited by these two inhibitors. In agreement with these data, we observed localization of the p85alpha subunit of phosphatidylinositol 3-kinase predominantly in the membrane fraction of Walker carcinosarcoma cells, indicating constitutive activation of this enzyme. We also investigated a role of Rho family proteins. Spontaneous development of polarity was almost completely suppressed by electroporation of the cells in the presence of 4 microg/ml C(3) exoenzyme, which specifically ADP-ribosylates and inactivates Rho. Two downstream targets of Rho, the Rho-activated kinases I and II, were also detected predominantly in the particulate membrane fraction, suggesting constitutive activation. A specific Rho-kinase inhibitor (Y-27632) blocked spontaneous polarization and migration in a concentration-dependent manner. Our results indicate that constitutive activation of the Rho/Rho-kinase pathway and of phosphatidylinositol 3-kinase plays an essential part in spontaneous development of polarity and cell locomotion of these cells.
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Affiliation(s)
- A Wicki
- Department of Pathology, University of Bern, Murtenstrasse 31, CH-3010 Bern, Switzerland
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22
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Stein J, Bauske R, Gerhard R. Analysis of low-molecular-weight GTP-binding proteins in two functionally different intestinal epithelial cell lines. Ann N Y Acad Sci 2001; 915:223-30. [PMID: 11193579 DOI: 10.1111/j.1749-6632.2000.tb05245.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Low molecular weight GTP-binding proteins are molecular switches that are believed to play pivotal roles in cell growth, differentiation, cytoskeletal organization, and vesicular trafficking. In this study, for the first time, members of this family of proteins in two functionally different intestinal epithelial cell lines are identified and characterized. [alpha-32P]GTP blot overlay assays of cytosolic and membranous fractions revealed the presence of specific GTP-binding proteins in the range of 20-30 kDa (small GTPases) in both fractions, with considerably higher amounts in the membranous insoluble fraction. Analysis by two-dimensional electrophoresis, immunoprecipitation using monoclonal and sequence-specific polyclonal antibodies, and C3 exoenzyme-mediated ADP ribosylation demonstrated the presence of Ras, Rap, Rho, Rac, Rab, and several other small GTPases. The pattern of small GTP-binding proteins corresponded to the characteristics of the cell lines. Caco-2 cells showed a Rab5 protein that is known to be involved in endocytosis but was not found in T84 cells. On the contrary Rab3 has been shown to participate in secretory processes. It is highly expressed in T84 cells (sixfold compared to Caco-2 cells).
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Affiliation(s)
- J Stein
- Medizinische Klinik II, Johann-Wolfgang-Goethe-University, Theodor-Stern-Kai 7, 60950 Frankfurt, Germany.
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23
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Verma A, Davis GE, Ihler GM. Infection of human endothelial cells with Bartonella bacilliformis is dependent on Rho and results in activation of Rho. Infect Immun 2000; 68:5960-9. [PMID: 10992508 PMCID: PMC101560 DOI: 10.1128/iai.68.10.5960-5969.2000] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bartonella bacilliformis was continuously internalized into human endothelial cells beginning shortly after addition of the bacteria and continuing for at least 24 h after infection in vitro, with a major increase in uptake occurring between 16 and 24 h. Preincubation of endothelial cells with C3 exoenzyme, which inactivated intracellular Rho-GTPase, blocked internalization of the bacteria. Addition of C3 exoenzyme at any time after addition of the bacteria blocked further internalization of bacteria, including the major uptake of bacteria internalized at 16 to 24 h. Rho, a key signaling protein in pathways involving actin organization, was directly shown to be activated in endothelial cells undergoing infection with B. bacilliformis, with maximal activation and translocation to the plasma membrane at 12 to 16 h. At late times of infection, most of the bacteria were found in a perinuclear location. Staining of the Golgi complex with specific markers, anti-human Golgin-97, anti-KDEL receptor, and BODIPY-TR ceramide, showed colocalization of bacteria in the Golgi complex region. Disruption of the Golgi complex with brefeldin A scattered the bacteria from this perinuclear location and resulted in inhibition of internalization of the bacteria in endothelial cells.
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Affiliation(s)
- A Verma
- Department of Medical Biochemistry and Genetics, Texas A&M University System, Health Science Center, College of Medicine, College Station, Texas 77843-1114, USA
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24
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Djouder N, Prepens U, Aktories K, Cavalie A. Inhibition of calcium release-activated calcium current by Rac/Cdc42-inactivating clostridial cytotoxins in RBL cells. J Biol Chem 2000; 275:18732-8. [PMID: 10749865 DOI: 10.1074/jbc.m001425200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Using large clostridial cytotoxins as tools, the role of Rho GTPases in activation of RBL 2H3 hm1 cells was studied. Clostridium difficile toxin B, which glucosylates Rho, Rac, and Cdc42 and Clostridium sordellii lethal toxin, which glucosylates Rac and Cdc42 but not Rho, inhibited the release of hexosaminidase from RBL cells mediated by the high affinity antigen receptor (FcepsilonRI). Additionally, toxin B and lethal toxin inhibited the intracellular Ca(2+) mobilization induced by FcepsilonRI-stimulation and thapsigargin, mainly by reducing the influx of extracellular Ca(2+). In patch clamp recordings, toxin B and lethal toxin inhibited the calcium release-activated calcium current by about 45%. Calcium release-activated calcium current, the receptor-stimulated Ca(2+) influx, and secretion were inhibited neither by the Rho-ADP-ribosylating C3-fusion toxin C2IN-C3 nor by the actin-ADP-ribosylating Clostridium botulinum C2 toxin. The data indicate that Rac and Cdc42 but not Rho are not only involved in late exocytosis events but are also involved in Ca(2+) mobilization most likely by regulating the Ca(2+) influx through calcium release-activated calcium channels activated via FcepsilonRI receptor in RBL cells.
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Affiliation(s)
- N Djouder
- Institut für Pharmakologie und Toxikologie der Universität Freiburg, D-79104 Freiburg, Germany
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25
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Yamakawa T, Tanaka S, Numaguchi K, Yamakawa Y, Motley ED, Ichihara S, Inagami T. Involvement of Rho-kinase in angiotensin II-induced hypertrophy of rat vascular smooth muscle cells. Hypertension 2000; 35:313-8. [PMID: 10642317 DOI: 10.1161/01.hyp.35.1.313] [Citation(s) in RCA: 138] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Angiotensin II (Ang II) is now believed to play a critical role in the pathogenesis of hypertrophy and/or hyperplasia of vascular smooth muscle cells (VSMCs). Several G(i)- and G(q)-coupled receptors, including the Ang II type 1 (AT(1)) receptor, activate Rho and Rho-associated kinase in Swiss 3T3 cells and cardiac myocytes. However, little is known about the role of Rho-kinase in Ang II-induced vascular hypertrophy in VSMCs. In the present study, we explored the role of Rho and Rho-kinase in Ang II-induced protein synthesis in VSMCs. In unstimulated cells, RhoA was observed predominantly in the cytosolic fraction, but it was translocated in part to the particulate fraction in response to Ang II (100 nmol/L). This effect was completely blocked by the AT(1) receptor blocker candesartan but not by the Ang II type 2 (AT(2)) receptor antagonist PD123319. Botulinum C(3) exoenzyme, which inactivated RhoA, attenuated Ang II-induced [(3)H]leucine incorporation. The specific Rho-kinase inhibitor, Y-27632, dose-dependently abolished Ang II-induced protein synthesis and also suppressed Ang II-induced c-fos mRNA expression. On the other hand, Y-27632 had no effect on Ang II-stimulated phosphorylation of p70 S6 kinase and extracellular signal-regulated kinase 1/2, which are reported to be involved in Ang II-induced protein synthesis, nor had it any effect on the Ang II-induced phosphorylation of PHAS-I, a heat- and acid-stable eIF-4E-binding protein. The phosphorylation of PHAS-I is regulating for translation initiation. These observations suggest that the Rho, Rho-kinase, and c-fos pathways may play a role in Ang II-induced hypertrophic changes of VSMCs through a novel pathway.
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Affiliation(s)
- T Yamakawa
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA.
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26
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Barth H, Olenik C, Sehr P, Schmidt G, Aktories K, Meyer DK. Neosynthesis and activation of Rho by Escherichia coli cytotoxic necrotizing factor (CNF1) reverse cytopathic effects of ADP-ribosylated Rho. J Biol Chem 1999; 274:27407-14. [PMID: 10488072 DOI: 10.1074/jbc.274.39.27407] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Clostridium botulinum exoenzyme C3 inactivates the small GTPase Rho by ADP-ribosylation. We used a C3 fusion toxin (C2IN-C3) with high cell accessibility to study the kinetics of Rho inactivation by ADP-ribosylation. In primary cultures of rat astroglial cells and Chinese hamster ovary cells, C2IN-C3 induced the complete ADP-ribosylation of RhoA and concomitantly the disassembly of stress fibers within 3 h. Removal of C2IN-C3 from the medium caused the recovery of stress fibers and normal cell morphology within 4 h. The regeneration was preceded by the appearance of non-ADP-ribosylated RhoA. Recovery of cell morphology was blocked by the proteasome inhibitor lactacystin and by the translation inhibitors cycloheximide and puromycin, indicating that intracellular degradation of the C3 fusion toxin and the neosynthesis of Rho were required for reversal of cell morphology. Escherichia coli cytotoxic necrotizing factor CNF1, which activates Rho by deamidation of Gln(63), caused reconstitution of stress fibers and cell morphology in C2IN-C3-treated cells within 30-60 min. The effect of CNF1 was independent of RhoA neosynthesis and occurred in the presence of completely ADP-ribosylated RhoA. The data show three novel findings; 1) the cytopathic effects of ADP-ribosylation of Rho are rapidly reversed by neosynthesis of Rho, 2) CNF1-induced deamidation activates ADP-ribosylated Rho, and 3) inhibition of Rho activation but not inhibition of Rho-effector interaction is a major mechanism underlying inhibition of cellular functions of Rho by ADP-ribosylation.
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Affiliation(s)
- H Barth
- Institut für Pharmakologie und Toxikologie der Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Strasse 5, D-79104 Freiburg, Germany
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27
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Numaguchi K, Eguchi S, Yamakawa T, Motley ED, Inagami T. Mechanotransduction of rat aortic vascular smooth muscle cells requires RhoA and intact actin filaments. Circ Res 1999; 85:5-11. [PMID: 10400905 DOI: 10.1161/01.res.85.1.5] [Citation(s) in RCA: 156] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The growth-promoting effect of mechanical stress on vascular smooth muscle cells (VSMCs) has been implicated in the progress of vascular disease in hypertension. Extracellular signal-regulated kinases (ERKs) have been implicated in cellular responses, such as vascular remodeling, induced by mechanical stretch. However, it remains to be determined how mechanical stretch activates ERKs. The cytoskeleton seems the most likely candidate for force transmission into the interior of the cell. Therefore, we examined (1) whether the cytoskeleton involves mechanical stretch-induced signaling, (2) whether Rho is activated by stretch, and (3) whether Rho mediates the stretch-induced signaling in rat cultured VSMCs. Mechanical stretch activated ERKs, with a peak response observed at 20 minutes, followed by a significant increase in DNA synthesis. Treatment with the ERK kinase-1 inhibitor, PD98059, inhibited the stretch-induced increase in DNA synthesis. Cytochalasin D, which selectively disrupts the network of actin filaments, markedly inhibited stretch-induced ERK activation. In the control state, RhoA was observed predominantly in the cytosolic fraction, but it was translocated in part to the particulate fraction in response to mechanical stretch. Botulinum C3 exoenzyme, which inactivates Rho p21 (known to participate in the reorganization of the actin cytoskeleton), attenuated stretch-induced ERK activation. Inhibition of Rho kinase (p160ROCK) also suppressed stretch-induced ERK activation dose dependently. Our results suggest that mechanotransduction in VSMCs is dependent on intact actin filaments, that Rho is activated by stretch, and that Rho/p160ROCK mediates stretch-induced ERK activation and vascular hyperplasia.
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Affiliation(s)
- K Numaguchi
- Department of Biochemistry, Vanderbilt University School of Medicine, Meharry Medical College, Nashville, TN, USA
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28
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Raman N, Atkinson SJ. Rho controls actin cytoskeletal assembly in renal epithelial cells during ATP depletion and recovery. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:C1312-24. [PMID: 10362594 DOI: 10.1152/ajpcell.1999.276.6.c1312] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Actin cytoskeletal disruption is a hallmark of ischemic injury and ATP depletion in a number of cell types, including renal epithelial cells. We manipulated Rho GTPase signaling by transfection and microinjection in LLC-PK proximal tubule epithelial cells and observed actin cytoskeletal organization following ATP depletion or recovery by confocal microscopy and quantitative image analysis. ATP depletion resulted in disruption of stress fibers, cortical F-actin, and apical actin bundles. Constitutively active RhoV14 prevented disruption of stress fibers and cortical F-actin during ATP depletion and enhanced the rate of stress fiber reassembly during recovery. Conversely, the Rho inhibitor C3 or dominant negative RhoN19 prevented recovery of F-actin assemblies upon repletion. Actin bundles in the apical microvilli and cytosolic F-actin were not affected by Rho signaling. Assembly of vinculin and paxillin into focal adhesions was disrupted by ATP depletion, and constitutively active RhoV14, although protecting stress fibers from disassembly, did not prevent dispersion of vinculin and paxillin, resulting in uncoupling of stress fiber and focal adhesion assembly. We propose that ATP depletion causes Rho inactivation during ischemia and that recovery of normal cellular architecture and function requires Rho.
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Affiliation(s)
- N Raman
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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29
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Beltman J, Erickson JR, Martin GA, Lyons JF, Cook SJ. C3 toxin activates the stress signaling pathways, JNK and p38, but antagonizes the activation of AP-1 in rat-1 cells. J Biol Chem 1999; 274:3772-80. [PMID: 9920930 DOI: 10.1074/jbc.274.6.3772] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lysophosphatidic acid (LPA) stimulates the c-Fos serum response element (SRE) by activating two distinct signal pathways regulated by the small GTPases, Ras and RhoA. Ras activates the ERK cascade leading to phosphorylation of the transcription factors Elk-1 and Sap1a at the Ets/TCF site. RhoA regulates an undefined pathway required for the activation of the SRF/CArG site. Here we have examined the role of the Ras and RhoA pathways in activation of the SRE and c-Fos expression in Rat-1 cells. Pertussis toxin and PD98059 strongly inhibited LPA-stimulated c-Fos expression and activation of a SRE:Luc reporter. C3 toxin completely inhibited RhoA function, partially inhibited SRE:Luc activity, but had no effect on LPA-stimulated c-Fos expression. Thus, in a physiological context the Ras-Raf-MEK-ERK pathway, but not RhoA, is required for LPA-stimulated c-Fos expression in Rat-1 cells. C3 toxin stimulated the stress-activated protein kinases JNK and p38 and potentiated c-Jun expression and phosphorylation; these properties were shared by another cellular stress agonist the protein kinase C inhibitor Ro-31-8220. However, C3 toxin alone or in combination with growth factors did not stimulate AP-1:Luc activity and actually antagonized the synergistic activation of AP-1:Luc observed in response to co-stimulation with growth factors and Ro-31-8220. These data indicate that C3 toxin is a cellular stress which antagonizes activation of AP-1 at a point downstream of stress-activated kinase activation or immediate-early gene induction.
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Affiliation(s)
- J Beltman
- ONYX Pharmaceuticals, Richmond, California 94806, USA
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30
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Xiong M, Elson G, Legarda D, Leibovich SJ. Production of vascular endothelial growth factor by murine macrophages: regulation by hypoxia, lactate, and the inducible nitric oxide synthase pathway. THE AMERICAN JOURNAL OF PATHOLOGY 1998; 153:587-98. [PMID: 9708818 PMCID: PMC1852978 DOI: 10.1016/s0002-9440(10)65601-5] [Citation(s) in RCA: 229] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/16/1998] [Indexed: 02/08/2023]
Abstract
Murine thioglycolate-induced peritoneal macrophages (MPMs) and the murine RAW264.7 macrophage-like cell line (RAW cells) constitutively produce vascular endothelial growth factor (VEGF). VEGF production is increased under hypoxic conditions or after cell activation with interferon-gamma (IFNgamma) and endotoxin (lipopolysaccharide, LPS). In contrast, tumor necrosis factor-alpha is produced only by IFNgamma/LPS-activated cells. Lactate (25 mmol/L) does not increase VEGF production by these cells. However, hypoxia, lactate, and IFNgamma/LPS-activated MPMs express angiogenic activity, whereas normoxic, nonactivated MPMs do not. Lack of angiogenic activity is not due to an antiangiogenic factor(s) in the medium of these cells. Angiogenic activity produced by hypoxia and lactate-treated MPMs is neutralized by anti-VEGF antibody, which also neutralizes most of the angiogenic activity produced by IFNgamma/LPS-activated MPMs. The inducible nitric oxide synthase inhibitors Ng-nitro-L-arginine-methyl ester (1.5 mmol/L) and aminoguanidine (1 mmol/L) block production of angiogenic activity by MPMs and RAW cells. In RAW cells, Ng-nitro-L-arginine-methyl ester and AG block IFNgamma/LPS-activated, but not constitutive, VEGF production, whereas in MPMs, neither constitutive nor IFNgamma/LPS-activated VEGF synthesis is affected. Synthesis of tumor necrosis factor-alpha is also unaffected. In contrast to normoxic, nonactivated MPMs, inducible nitric oxide synthase-inhibited, IFNgamma/LPS-activated MPMs produce an antiangiogenic factor(s). We conclude that VEGF is a major contributor to macrophage-derived angiogenic activity, and that activation by hypoxia, lactate, or IFNgamma/LPS switches macrophage-derived VEGF from a nonangiogenic to an angiogenic state. This switch may involve a posttranslational modification of VEGF, possibly by the process of ADP-ribosylation. ADP-ribosylation by MPM cytosolic extracts or by cholera toxin switches rVEGF165 from an angiogenic to a nonangiogenic state. In IFNgamma/LPS-activated MPMs, the inducible nitric oxide synthase-dependent pathway also regulates the expression of an antiangiogenic factor(s) that antagonizes the bioactivity of VEGF and provides an additional regulatory pathway controlling the angiogenic phenotype of macrophages.
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Affiliation(s)
- M Xiong
- Department of Anatomy, Cell Biology & Injury Sciences, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark 07103, USA
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Nobes CD, Lauritzen I, Mattei MG, Paris S, Hall A, Chardin P. A new member of the Rho family, Rnd1, promotes disassembly of actin filament structures and loss of cell adhesion. J Cell Biol 1998; 141:187-97. [PMID: 9531558 PMCID: PMC2132722 DOI: 10.1083/jcb.141.1.187] [Citation(s) in RCA: 284] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Members of the Rho GTPase family regulate the organization of the actin cytoskeleton in response to extracellular growth factors. We have identified three proteins that form a distinct branch of the Rho family: Rnd1, expressed mostly in brain and liver; Rnd2, highly expressed in testis; and Rnd3/RhoE, showing a ubiquitous low expression. At the subcellular level, Rnd1 is concentrated at adherens junctions both in confluent fibroblasts and in epithelial cells. Rnd1 has a low affinity for GDP and spontaneously exchanges nucleotide rapidly in a physiological buffer. Furthermore, Rnd1 lacks intrinsic GTPase activity suggesting that in vivo, it might be constitutively in a GTP-bound form. Expression of Rnd1 or Rnd3/RhoE in fibroblasts inhibits the formation of actin stress fibers, membrane ruffles, and integrin-based focal adhesions and induces loss of cell-substrate adhesion leading to cell rounding (hence Rnd for "round"). We suggest that these proteins control rearrangements of the actin cytoskeleton and changes in cell adhesion.
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Affiliation(s)
- C D Nobes
- Medical Research Council Laboratory for Molecular Cell Biology, Cancer Research Campaign Oncogene and Signal Transduction Group and Department of Biochemistry, University College London, London WC1E 7BT, United Kingdom.
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Aoki H, Izumo S, Sadoshima J. Angiotensin II activates RhoA in cardiac myocytes: a critical role of RhoA in angiotensin II-induced premyofibril formation. Circ Res 1998; 82:666-76. [PMID: 9546375 DOI: 10.1161/01.res.82.6.666] [Citation(s) in RCA: 163] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The organization of actin into striated fibers (myofibrils) is one of the major features of cardiac hypertrophy. However, its signal transduction mechanism is not well understood. Although Rho-family small G proteins have been implicated in actin organization in many cell types, it is not fully elucidated whether Rho mediates the organization of actin fibers by hypertrophic stimuli in cardiac myocytes. Therefore, we examined (1) whether Rho is activated by the hypertrophic stimulus, angiotensin II (Ang II), and (2) whether Rho mediates the Ang II-induced organization of actin fibers in cultured neonatal rat cardiac myocytes. Treatment of myocytes with Ang II caused a rapid formation of both striated (mature myofibrils) and nonstriated (premyofibrils) actin fibers within 30 minutes, as determined by phalloidin stainings of the polymerized actin and troponin T stainings. Immunoblot analyses and immunostainings have indicated that cardiac myocytes express RhoA, but RhoB is undetectable. In the control state, RhoA was observed predominantly in the cytosolic fraction, but it was translocated in part to the particulate fraction in response to Ang II, consistent with activation of RhoA by Ang II. Incubation of myocytes with exoenzyme C3 for 48 hours completely ADP-ribosylated Rho in vivo. The C3 treatment abolished formation of premyofibrils induced by Ang II, suggesting that Ang II causes premyofibril formation via a Rho-dependent mechanism. The Ang II-induced mature myofibril formation was only partly abolished by C3. Expression of constitutively active RhoA (V14RhoA) caused the formation of premyofibrils but not mature myofibrils. The C3 treatment inhibited Ang II-induced atrial natriuretic factor induction, whereas it had no effect on c-fos induction. These results indicate that RhoA is activated by Ang II and mediates the Ang II-induced formation of premyofibrils and induction of a subset of genes. Distinct signaling mechanisms seem to be responsible for striated mature myofibril formation by Ang II.
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Affiliation(s)
- H Aoki
- Cardiovascular Research Center, Division of Cardiology, University of Michigan Medical Center, Ann Arbor, USA
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Barth H, Hofmann F, Olenik C, Just I, Aktories K. The N-terminal part of the enzyme component (C2I) of the binary Clostridium botulinum C2 toxin interacts with the binding component C2II and functions as a carrier system for a Rho ADP-ribosylating C3-like fusion toxin. Infect Immun 1998; 66:1364-9. [PMID: 9529054 PMCID: PMC108061 DOI: 10.1128/iai.66.4.1364-1369.1998] [Citation(s) in RCA: 142] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The binary actin-ADP-ribosylating Clostridium botulinum C2 toxin consists of the enzyme component C2I and the binding component C2II, which are separate proteins. The active component C2I enters cells through C2II by receptor-mediated endocytosis and membrane translocation. The N-terminal part of C2I (C2IN), which consists of 225 amino acid residues but lacks ADP-ribosyltransferase activity, was identified as the C2II contact site. A fusion protein (C2IN-C3) of C2IN and the full-length C3-like ADP-ribosyltransferase from Clostridium limosum was constructed. The fusion protein C2IN-C3 ADP-ribosylated Rho but not actin in CHO cell lysates. Together with C2II, C2IN-C3 induced complete rounding up of CHO and HeLa cells after incubation for 3 h. No cell rounding was observed without C2II or with the original C3-like transferase from C. limosum. The data indicate that the N-terminal 225 amino acid residues of C2I are sufficient to cause the cellular uptake of C. limosum transferase via the binding component of C2II, thereby increasing the cytotoxicity of the C3-like exoenzyme several hundred-fold.
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Affiliation(s)
- H Barth
- Institut für Pharmakologie und Toxikologie der Albert-Ludwigs-Universität Freiburg, Germany
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Boukharov AA, Cohen CM. Guanine nucleotide-dependent translocation of RhoA from cytosol to high affinity membrane binding sites in human erythrocytes. Biochem J 1998; 330 ( Pt 3):1391-8. [PMID: 9494111 PMCID: PMC1219287 DOI: 10.1042/bj3301391] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The translocation of the small GTP-binding protein Rho from the cytosolic to membrane-bound form is an early step in many cellular signal-transduction events, but little is known regarding the mechanism of Rho association with the plasma membrane. We have used membranes from human erythrocytes to uncover a novel class of integral membrane components involved in the Rho-membrane association. Membranes of human erythrocytes contain several proteins of the Ras superfamily. Using specific antibodies and C3 exoenzyme of Clostridium botulinum we have identified one of them as RhoA. This protein was detected in both cytosol and membrane fractions of hypotonically lysed erythrocytes. We found that cytosolic Rho bound specifically to the cytoplasmic surface of the erythrocyte membrane and that the translocation of Rho to the membrane was absolutely dependent on the prior incubation of the cytosol with guanosine 5'--gamma-thio-triphosphate (1-50 microM) at low Mg2+ concentration. Rho binding sites could not be extracted from the membrane using conditions that extracted all other peripheral proteins and were unaffected by heat treatment and protease digestion. Rho binding was saturable, with a Kd in the range 1-5.0 nM, and the number of binding sites was estimated to be approx. (1-2) x 10(3) sites per cell. This is the first report of Rho binding to integral membrane components. The identity of these components may reveal novel aspects of the mechanism by which Rho exerts its multiple biochemical effects.
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Affiliation(s)
- A A Boukharov
- Department of Biomedical Research, St. Elizabeth's Medical Center of Boston, Boston, MA 02135, USA
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35
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6.10 Bacterial Exotoxins. J Microbiol Methods 1998. [DOI: 10.1016/s0580-9517(08)70291-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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36
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Aepfelbacher M, Essler M, Huber E, Sugai M, Weber PC. Bacterial toxins block endothelial wound repair. Evidence that Rho GTPases control cytoskeletal rearrangements in migrating endothelial cells. Arterioscler Thromb Vasc Biol 1997; 17:1623-9. [PMID: 9327754 DOI: 10.1161/01.atv.17.9.1623] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We investigated the effect of bacterial toxins that modify and inactivate Rho GTP-binding proteins on the migratory response of endothelial cells to wounding. C3-transferase from Clostridium botulinum, EDIN from Staphylococcus aureus, and toxin A from Clostridium difficile blocked migration of human umbilical vein endothelial cells (HUVECs) in an in vitro wound repair assay. Migrating HUVECs expressed actin microspikes (maximum at 10 minutes after wounding), ruffles (maximum at 12 hours), and fibers (maximum at 24 hours), and within these actin structures, vinculin-containing focal complexes/adhesions were formed. C3-Transferase ADP ribosylated RhoA, RhoB, and RhoC in HUVECs and abolished the formation of actin stress fibers/focal adhesions but had no effect on expression of microspikes, ruffles, or the associated vinculin-containing focal complexes. Similar results were obtained with EDIN and toxin A. These results indicate that endothelial cells migrating into a wounded area express distinct combinations of actin/vinculin structures in a spatially and temporally coordinated manner. The GTPase Rho selectively controls the formation of actin fibers/focal adhesions that occurs 2 to 24 hours after wounding. A mechanism is proposed by which Rho-specific bacterial toxins could influence vascular repair, angiogenesis, or atherosclerosis.
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Affiliation(s)
- M Aepfelbacher
- Institut für Prophylaxe und Epidemiologie der Kreislaufkrankheiten, University of Munich, Germany
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37
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Mackay DJ, Esch F, Furthmayr H, Hall A. Rho- and rac-dependent assembly of focal adhesion complexes and actin filaments in permeabilized fibroblasts: an essential role for ezrin/radixin/moesin proteins. J Cell Biol 1997; 138:927-38. [PMID: 9265657 PMCID: PMC2138043 DOI: 10.1083/jcb.138.4.927] [Citation(s) in RCA: 252] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/1997] [Revised: 06/06/1997] [Indexed: 02/05/2023] Open
Abstract
The small GTPases Rho and Rac regulate actin filament assembly and the formation of integrin adhesion complexes to produce stress fibers and lamellipodia, respectively, in mammalian cells. Although numerous candidate effectors that might mediate these responses have been identified using the yeast two-hybrid and affinity purification techniques, their cellular roles remain unclear. We now describe a biological assay that allows components of the Rho and Rac signaling pathways to be identified. Permeabilization of serum-starved Swiss 3T3 cells with digitonin in the presence of guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS) induces both actin filament and focal adhesion complex assembly through activation of endogenous Rho and Rac. These responses are lost when GTPgammaS is added 6 min after permeabilization, but can be reconstituted using concentrated cytosolic extracts. We have achieved a 10,000-fold purification of the activity present in pig brain cytosol and protein sequence analysis shows it to contain moesin. Using recombinant proteins, we show that moesin and its close relatives ezrin and radixin can reconstitute stress fiber assembly, cortical actin polymerization and focal complex formation in response to activation of Rho and Rac.
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Affiliation(s)
- D J Mackay
- MRC Laboratory for Molecular Cell Biology, University College London, United Kingdom
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38
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Zhang Q, Magnusson MK, Mosher DF. Lysophosphatidic acid and microtubule-destabilizing agents stimulate fibronectin matrix assembly through Rho-dependent actin stress fiber formation and cell contraction. Mol Biol Cell 1997; 8:1415-25. [PMID: 9285815 PMCID: PMC276166 DOI: 10.1091/mbc.8.8.1415] [Citation(s) in RCA: 167] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Fibronectin (FN) matrix assembly is a cell-dependent process mediated by cell surface-binding sites for the 70-kDa amino-terminal region of FN. We have shown recently that lysophosphatidic acid (LPA) is a stimulator of FN matrix assembly. Disruption of microtubules has been shown to mimic some of the intracellular effects of LPA including the formation of actin stress fibers and myosin light chain phosphorylation. We compared the effects of microtubule disruption and LPA on FN binding and actin cytoskeleton organization. The disruption of microtubules by nocodazole or vinblastine increased FN binding to adherent cells. The modulation of binding sites was rapid, dynamic, and reversible. Enhanced binding was due to increases in both the number and affinity of binding sites. These effects are similar to the effects of LPA on FN binding. Binding induced by nocodazole was inhibited by the microtubule-stabilizing agent Taxol but not by pretreatment with a concentration of phospholipase B that totally abolished the stimulatory effect of LPA. Fluorescence microscopy revealed a close correlation among actin stress fiber formation, cell contraction, and FN binding. Blockage of the small GTP binding protein Rho or actin-myosin interactions inhibited the effects of both nocodazole and LPA on FN binding. These observations demonstrate that Rho-dependent actin stress fiber formation and cell contraction induce increased FN binding and represent a rapid labile way that cells can modulate FN matrix assembly.
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Affiliation(s)
- Q Zhang
- Department of Medicine, University of Wisconsin-Madison 53706, USA
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39
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Santos MF, McCormack SA, Guo Z, Okolicany J, Zheng Y, Johnson LR, Tigyi G. Rho proteins play a critical role in cell migration during the early phase of mucosal restitution. J Clin Invest 1997; 100:216-25. [PMID: 9202074 PMCID: PMC508182 DOI: 10.1172/jci119515] [Citation(s) in RCA: 140] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
In the intestine, several growth factors stimulate migration of epithelial cells, contributing to the maintenance of tissue integrity. The Ras-like GTPase Rho regulates a signal transduction pathway linking growth factor receptors to the formation of actin stress fibers and focal adhesions, presumed to be important for motility. Using an in vitro wound-induced migration assay, we have examined the role of Rho GTPases in the migration of IEC-6 and Caco-2 cells, and provide evidence that the Rho GTPases play an essential role in the initial phase of mucosal wound healing. Treatment of the cells with Clostridium difficile toxins A and B, inhibitors of the Rho family GTPases inhibited migration in a dose-dependent fashion. Microinjection of the inhibitory exchange factor Rho-guanine nucleotide dissociation inhibitor (GDI), or Clostridium botulinum C3 ADP-ribosyl transferase (C3) toxin, a Rho-ADP-ribosylating exoenzyme, potently inhibited migration. Microinjection of RhoT19N, a dominant negative form of RhoA, or in vitro ADP-ribosylated RhoA impaired the ability of cells to migrate. Rho-GDI and C3 exoenzyme also inhibited EGF-induced migration of IEC-6 cells. These results demonstrate that Rho is required for endogenous and EGF-induced migration of small intestinal crypt cells, and that Rho proteins are essential elements of a mechanism by which growth factors induce cell migration to restitute mucosal integrity.
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Affiliation(s)
- M F Santos
- Department of Physiology and Biophysics, University of Tennessee, College of Medicine, Memphis, Tennessee 38163, USA
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40
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Schmidt G, Sehr P, Wilm M, Selzer J, Mann M, Aktories K. Gln 63 of Rho is deamidated by Escherichia coli cytotoxic necrotizing factor-1. Nature 1997; 387:725-9. [PMID: 9192900 DOI: 10.1038/42735] [Citation(s) in RCA: 463] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The actin cytoskeleton is regulated by GTP-hydrolysing proteins, the Rho GTPases, which act as molecular switches in diverse signal-transduction processes. Various bacterial toxins can inactivate Rho GTPases by ADP-ribosylation or glucosylation. Previous research has identified Rho proteins as putative targets for Escherichia coli cytotoxic necrotizing factors 1 and 2 (CNF1 and 2). These toxins induce actin assembly and multinucleation in culture cells. Here we show that treatment of RhoA with CNF1 inhibits the intrinsic GTPase activity of RhoA and completely blocks GTPase activity stimulated by the Rho-GTPase-activating protein (rhoGAP). Analysis by mass spectrometry and amino-acid sequencing of proteolytic peptides derived from CNF1-treated RhoA indicate that CNF1 induces deamidation of a glutamine residue at position 63 (Gln 63) to give constitutively active Rho protein.
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Affiliation(s)
- G Schmidt
- Institut für Pharmakologie und Toxikologie der Albert-Ludwigs-Universität Freiburg, Germany
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41
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Karnam P, Standaert ML, Galloway L, Farese RV. Activation and translocation of Rho (and ADP ribosylation factor) by insulin in rat adipocytes. Apparent involvement of phosphatidylinositol 3-kinase. J Biol Chem 1997; 272:6136-40. [PMID: 9045624 DOI: 10.1074/jbc.272.10.6136] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Insulin reportedly (Standaert, M. L., Avignon, A., Yamada, K., Bandyopadhyay, G., and Farese, R. V. (1996) Biochem. J. 313, 1039-1046) activates phospholipase D (PLD)-dependent hydrolysis of phosphatidylcholine (PC) in plasma membranes of rat adipocytes by a mechanism that may involve wortmannin-sensitive phosphatidylinositol (PI) 3-kinase. Because Rho and ADP ribosylation factor (ARF) activate PC-PLD, we questioned whether these small G-proteins are regulated by insulin and PI 3-kinase. We found that insulin provoked a rapid translocation of both Rho and ARF to the plasma membrane and increased GTP loading of Rho. Wortmannin and LY294002 inhibited Rho translocation in intact adipocytes, and the polyphosphoinositide, PI 4,5-(PO4)2, stimulated Rho translocation in adipocyte homogenates. On the other hand, wortmannin did not block GTP loading of Rho. Guanosine 5'-3-O-(thio)triphosphate stimulated both Rho and ARF translocation and activated PC-PLD in homogenates. C3 transferase, which inhibits and depletes Rho, inhibited PC-PLD activation by insulin in intact adipocytes. C3 transferase also inhibited insulin stimulation of [3H]2-deoxyglucose uptake. Our findings suggest that: (a) insulin translocates Rho by a PI 3-kinase-dependent mechanism, but another factor is responsible for GTP loading of Rho; (b) both Rho and ARF may contribute to PC-PLD activation during insulin action; and (c) Rho may be required for insulin stimulation of glucose transport.
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Affiliation(s)
- P Karnam
- J. A. Haley Veterans' Hospital Research Service and the Departments of Internal Medicine and Biochemistry/Molecular Biology, University of South Florida, Tampa, Florida 33612, USA
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42
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Tilly BC, Edixhoven MJ, Tertoolen LG, Morii N, Saitoh Y, Narumiya S, de Jonge HR. Activation of the osmo-sensitive chloride conductance involves P21rho and is accompanied by a transient reorganization of the F-actin cytoskeleton. Mol Biol Cell 1996; 7:1419-27. [PMID: 8885236 PMCID: PMC275991 DOI: 10.1091/mbc.7.9.1419] [Citation(s) in RCA: 132] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Hypo-osmotic stimulation of human Intestine 407 cells rapidly activated compensatory CL- and K+ conductances that limited excessive cell swelling and, finally, restored the original cell volume. Osmotic cell swelling was accompanied by a rapid and transient reorganization of the F-actin cytoskeleton, affecting both stress fibers as well as apical ruffles. In addition, an increase in total cellular F-actin was observed. Pretreatment of the cells with recombinant Clostridium botulinum C3 exoenzyme, but not with mutant enzyme (C3-E173Q) devoid of ADP-ribosyltransferase activity, greatly reduced the activation of the osmo-sensitive anion efflux, suggesting a role for the ras-related GTPase p21rho. In contrast, introducing dominant negative N17-p21rac into the cells did not affect the volume-sensitive efflux. Cell swelling-induced reorganization of F-actin coincided with a transient, C3 exoenzyme-sensitive tyrosine phosphorylation of p125 focal adhesion kinase (p125FAK) as well as with an increase in phosphatidylinositol-3-kinase (PtdIns-3-kinase) activity. Pretreatment of the cells with wortmannin, a specific inhibitor of PtdIns-3-kinase, largely inhibited the volume-sensitive ion efflux. Taken together, our results indicate the involvement of a p21rho signaling cascade and actin filaments in the activation of volume-sensitive chloride channels.
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Affiliation(s)
- B C Tilly
- Department of Biochemistry, Cardiovascular Research Institute COEUR, Medical Faculty, Erasmus University, Rotterdam, The Netherlands
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43
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Malcolm KC, Elliott CM, Exton JH. Evidence for Rho-mediated agonist stimulation of phospholipase D in rat1 fibroblasts. Effects of Clostridium botulinum C3 exoenzyme. J Biol Chem 1996; 271:13135-9. [PMID: 8662844 DOI: 10.1074/jbc.271.22.13135] [Citation(s) in RCA: 122] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Small GTP-binding proteins of the Rho family are implicated in the in vitro regulation of phosphatidylcholine hydrolysis by phospholipase D (PLD). However, their role in agonist-stimulated PLD activity in whole cells is not clear. The ribosyltransferase C3 from Clostridium botulinum modifies Rho proteins and inhibits their function. When introduced into rat1 fibroblasts by scrape-loading, C3 inhibited PLD activity stimulated by lysophosphatidic acid (LPA), endothelin-1, or phorbol ester. Neither the time course nor agonist dose response for LPA-stimulated PLD activity was altered in C3-treated cells. In contrast to the effects of C3 on PLD activity, agonist-stimulated phosphatidylinositol-phospholipase C activity was not altered in C3-treated cells. Surprisingly, C3 treatment led to a decrease in the amount of RhoA protein, indicating that the loss of PLD activity in response to agonist was partly due to the loss of Rho proteins. As described previously, C3 treatment led to the inhibition of LPA-stimulated actin filament formation. However, disruption of actin filaments with cytochalasin D caused only a minor inhibition of LPA-stimulated PLD activity. Interestingly, stimulation of cells with LPA caused a rapid enrichment of RhoA in the particulate fraction of cell lysates. These data support an in vivo role for RhoA in agonist-stimulated PLD activity that is separate from its role in actin fiber formation.
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Affiliation(s)
- K C Malcolm
- Howard Hughes Medical Institute and the Departments of Molecular Physiology and Biophysics and Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0295, USA
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Prepens U, Just I, von Eichel-Streiber C, Aktories K. Inhibition of Fc epsilon-RI-mediated activation of rat basophilic leukemia cells by Clostridium difficile toxin B (monoglucosyltransferase). J Biol Chem 1996; 271:7324-9. [PMID: 8631752 DOI: 10.1074/jbc.271.13.7324] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Treatment of rat basophilic leukemia (RBL) 2H3-hm1 cells with Clostridium difficile toxin B (2 ng/ml), which reportedly depolymerizes the actin cytoskeleton, blocked [3H]serotonin release induced by 2,4-dinitrophenyl-bovine serum albumin, carbachol, mastoparan, and reduced ionophore A23187-stimulated degranulation by about 55-60%. In lysates of RBL cells, toxin B 14C-glucosylated two major and one minor protein. By using two-dimensional gel electrophoresis and immunoblotting, RhoA and Cdc42 were identified as protein substrates of toxin B. In contrast to toxin B, Clostridium botulinum transferase C3 that selectively inactivates RhoA by ADP-ribosylation did not inhibit degranulation up to a concentration of 150 microg/ml. Antigen-stimulated tyrosine phosphorylation of a 110-kDa protein was inhibited by toxin B as well as by the phosphatidylinositol 3-kinase inhibitor wortmannin. Depolymerization of the microfilament cytoskeleton of RBL cells by C. botulinum C2 toxin or cytochalasin D resulted in an increased [3H]serotonin release induced by antigen, carbachol, mastoparan, or by calcium ionophore A23187, but without affecting toxin B-induced inhibition of degranulation. The data indicate that toxin B inhibits activation of RBL cells by glucosylation of low molecular mass GTP-binding proteins of the Rho subfamily (most likely Cdc42) by a mechanism not involving the actin cytoskeleton.
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Affiliation(s)
- U Prepens
- Institut für Pharmakologie und Toxikologie der Albert-Ludwigs-Universität Freiburg, Germany
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