1
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Koh AEH, Subbiah SK, Farhana A, Alam MK, Mok PL. Mitigation of Sodium Iodate-Induced Cytotoxicity in Retinal Pigment Epithelial Cells in vitro by Transgenic Erythropoietin-Expressing Mesenchymal Stem Cells. Front Cell Dev Biol 2021; 9:652065. [PMID: 33937251 PMCID: PMC8082501 DOI: 10.3389/fcell.2021.652065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 03/15/2021] [Indexed: 12/20/2022] Open
Abstract
Mesenchymal stem cells (MSC) have shown promise in restoring the vision of patients in clinical trials. However, this therapeutic effect is not observed in every treated patient and is possibly due to the inefficacies of cell delivery and high cell death following transplantation. Utilizing erythropoietin can significantly enhance the regenerative properties of MSCs and hence improve retinal neuron survivability in oxidative stress. Hence, this study aimed to investigate the efficacy of conditioned medium (CM) obtained from transgenic human erythropoietin-expressing MSCs (MSC EPO ) in protecting human retinal pigment epithelial cells from sodium iodate (NaIO3)-induced cell death. Human MSC and MSC EPO were first cultured to obtain conditioned media (CM). The IC50 of NaIO3 in the ARPE-19 culture was then determined by an MTT assay. After that, the efficacy of both MSC-CM and MSC-CM EPO in ARPE-19 cell survival were compared at 24 and 48 h after NaIO3 treatment with MTT. The treatment effects on mitochondrial membrane potential was then measured by a JC-1 flow cytometric assay. The MTT results indicated a corresponding increase in cell survivability (5-58%) in the ARPE-19 cell cultures. In comparison to MSC-CM, the use of conditioned medium collected from the MSC-CM EPO further enhanced the rate of ARPE-19 survivability at 24 h (P < 0.05) and 48 h (P < 0.05) in the presence of NaIO3. Furthermore, more than 90% were found viable with the JC-1 assay after MSC-CM EPO treatment, showing a positive implication on the mitochondrial dynamics of ARPE-19. The MSC-CM EPO provided an enhanced mitigating effect against NaIO3-induced ARPE-19 cell death over that of MSC-CM alone during the early phase of the treatment, and it may act as a future therapy in treating retinal degenerative diseases.
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Affiliation(s)
- Avin Ee-Hwan Koh
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, UPM, Seri Kembangan, Malaysia
| | - Suresh Kumar Subbiah
- Department of Medical Microbiology and Parasitology, Universiti Putra Malaysia, UPM, Seri Kembangan, Malaysia.,Genetics and Regenerative Medicine Research Group, Universiti Putra Malaysia, UPM, Seri Kembangan, Malaysia.,Department of Biotechnology, Bharath Institute of Higher Education and Research, Chennai, India
| | - Aisha Farhana
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Jouf University, Sakaka, Saudi Arabia
| | | | - Pooi Ling Mok
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, UPM, Seri Kembangan, Malaysia.,Genetics and Regenerative Medicine Research Group, Universiti Putra Malaysia, UPM, Seri Kembangan, Malaysia.,Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Jouf University, Sakaka, Saudi Arabia
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2
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Luinenburg DG, Dinitzen AB, Flohr Svendsen A, Cengiz R, Ausema A, Weersing E, Bystrykh L, de Haan G. Persistent expression of microRNA-125a targets is required to induce murine hematopoietic stem cell repopulating activity. Exp Hematol 2021; 94:47-59.e5. [PMID: 33333212 DOI: 10.1016/j.exphem.2020.12.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 12/10/2020] [Accepted: 12/11/2020] [Indexed: 01/17/2023]
Abstract
MicroRNAs (miRs) are small noncoding RNAs that regulate gene expression posttranscriptionally by binding to the 3' untranslated regions of their target mRNAs. The evolutionarily conserved microRNA-125a (miR-125a) is highly expressed in both murine and human hematopoietic stem cells (HSCs), and previous studies have found that miR-125 strongly enhances self-renewal of HSCs and progenitors. In this study we explored whether temporary overexpression of miR-125a would be sufficient to permanently increase HSC self-renewal or, rather, whether persistent overexpression of miR-125a is required. We used three complementary in vivo approaches to reversibly enforce expression of miR-125a in murine HSCs. Additionally, we interrogated the underlying molecular mechanisms responsible for the functional changes that occur in HSCs on overexpression of miR-125a. Our data indicate that continuous expression of miR-125a is required to enhance HSC activity. Our molecular analysis confirms changes in pathways that explain the characteristics of miR-125a overexpressing HSCs. Moreover, it provides several novel putative miR-125a targets, but also highlights the complex molecular changes that collectively lead to enhanced HSC function.
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Affiliation(s)
- Daniëlle G Luinenburg
- European Research Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Alexander Bak Dinitzen
- European Research Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Arthur Flohr Svendsen
- European Research Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Roza Cengiz
- European Research Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Albertina Ausema
- European Research Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Ellen Weersing
- European Research Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Leonid Bystrykh
- European Research Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Gerald de Haan
- European Research Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
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3
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Carabias A, Gómez-Hernández M, de Cima S, Rodríguez-Blázquez A, Morán-Vaquero A, González-Sáenz P, Guerrero C, de Pereda JM. Mechanisms of autoregulation of C3G, activator of the GTPase Rap1, and its catalytic deregulation in lymphomas. Sci Signal 2020; 13:13/647/eabb7075. [PMID: 32873726 DOI: 10.1126/scisignal.abb7075] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
C3G is a guanine nucleotide exchange factor (GEF) that regulates cell adhesion and migration by activating the GTPase Rap1. The GEF activity of C3G is stimulated by the adaptor proteins Crk and CrkL and by tyrosine phosphorylation. Here, we uncovered mechanisms of C3G autoinhibition and activation. Specifically, we found that two intramolecular interactions regulate the activity of C3G. First, an autoinhibitory region (AIR) within the central domain of C3G binds to and blocks the catalytic Cdc25H domain. Second, the binding of the protein's N-terminal domain to its Ras exchanger motif (REM) is required for its GEF activity. CrkL activated C3G by displacing the AIR/Cdc25HD interaction. Two missense mutations in the AIR found in non-Hodgkin's lymphomas, Y554H and M555K, disrupted the autoinhibitory mechanism. Expression of C3G-Y554H or C3G-M555K in Ba/F3 pro-B cells caused constitutive activation of Rap1 and, consequently, the integrin LFA-1. Our findings suggest that sustained Rap1 activation by deregulated C3G might promote progression of lymphomas and that designing therapeutics to target C3G might treat these malignancies.
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Affiliation(s)
- Arturo Carabias
- Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, 37007 Salamanca, Spain
| | - María Gómez-Hernández
- Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, 37007 Salamanca, Spain
| | - Sergio de Cima
- Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, 37007 Salamanca, Spain
| | - Antonio Rodríguez-Blázquez
- Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, 37007 Salamanca, Spain
| | - Alba Morán-Vaquero
- Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, 37007 Salamanca, Spain
| | - Patricia González-Sáenz
- Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, 37007 Salamanca, Spain
| | - Carmen Guerrero
- Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, 37007 Salamanca, Spain.,Departamento de Medicina, Facultad de Medicina, Universidad de Salamanca, Instituto de Investigación Biomédica de Salamanca (IBSAL), 37007 Salamanca, Spain
| | - José M de Pereda
- Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, 37007 Salamanca, Spain.
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4
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Edelmann B, Gupta N, Schnoeder TM, Oelschlegel AM, Shahzad K, Goldschmidt J, Philipsen L, Weinert S, Ghosh A, Saalfeld FC, Nimmagadda SC, Müller P, Braun-Dullaeus R, Mohr J, Wolleschak D, Kliche S, Amthauer H, Heidel FH, Schraven B, Isermann B, Müller AJ, Fischer T. JAK2-V617F promotes venous thrombosis through β1/β2 integrin activation. J Clin Invest 2018; 128:4359-4371. [PMID: 30024857 DOI: 10.1172/jci90312] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 07/03/2018] [Indexed: 12/18/2022] Open
Abstract
JAK2-V617F-positive chronic myeloproliferative neoplasia (CMN) commonly displays dysfunction of integrins and adhesion molecules expressed on platelets, erythrocytes, and leukocytes. However, the mechanism by which the 2 major leukocyte integrin chains, β1 and β2, may contribute to CMN pathophysiology remained unclear. β1 (α4β1; VLA-4) and β2 (αLβ2; LFA-1) integrins are essential regulators for attachment of leukocytes to endothelial cells. We here showed enhanced adhesion of granulocytes from mice with JAK2-V617F knockin (JAK2+/VF mice) to vascular cell adhesion molecule 1- (VCAM1-) and intercellular adhesion molecule 1-coated (ICAM1-coated) surfaces. Soluble VCAM1 and ICAM1 ligand binding assays revealed increased affinity of β1 and β2 integrins for their respective ligands. For β1 integrins, this correlated with a structural change from the low- to the high-affinity conformation induced by JAK2-V617F. JAK2-V617F triggered constitutive activation of the integrin inside-out signaling molecule Rap1, resulting in translocation toward the cell membrane. Employing a venous thrombosis model, we demonstrated that neutralizing anti-VLA-4 and anti-β2 integrin antibodies suppress pathologic thrombosis as observed in JAK2+/VF mice. In addition, aberrant homing of JAK2+/VF leukocytes to the spleen was inhibited by neutralizing anti-β2 antibodies and by pharmacologic inhibition of Rap1. Thus, our findings identified cross-talk between JAK2-V617F and integrin activation promoting pathologic thrombosis and abnormal trafficking of leukocytes to the spleen.
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Affiliation(s)
- Bärbel Edelmann
- Department of Hematology and Oncology, Medical Center, Otto-von-Guericke University, Magdeburg, Germany.,Gesundheitscampus Immunologie, Infektiologie und Inflammation (GCI3), Medical Center, Otto-von-Guericke University, Magdeburg, Germany
| | - Nibedita Gupta
- Department of Hematology and Oncology, Medical Center, Otto-von-Guericke University, Magdeburg, Germany.,Gesundheitscampus Immunologie, Infektiologie und Inflammation (GCI3), Medical Center, Otto-von-Guericke University, Magdeburg, Germany
| | - Tina M Schnoeder
- Department of Hematology and Oncology, Medical Center, Otto-von-Guericke University, Magdeburg, Germany.,Internal Medicine II, Hematology and Oncology, University Hospital Jena, Jena, Germany.,Leibniz Institute on Aging, Fritz-Lipmann-Institute, Jena, Germany
| | - Anja M Oelschlegel
- Leibniz Institute for Neurobiology, Magdeburg, Germany.,Institute of Anatomy
| | | | | | - Lars Philipsen
- Gesundheitscampus Immunologie, Infektiologie und Inflammation (GCI3), Medical Center, Otto-von-Guericke University, Magdeburg, Germany.,Institute of Molecular and Clinical Immunology, and
| | - Soenke Weinert
- Gesundheitscampus Immunologie, Infektiologie und Inflammation (GCI3), Medical Center, Otto-von-Guericke University, Magdeburg, Germany.,Department of Cardiology and Angiology, Medical Center, Otto-von-Guericke University, Magdeburg, Germany
| | - Aniket Ghosh
- Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Felix C Saalfeld
- Department of Hematology and Oncology, Medical Center, Otto-von-Guericke University, Magdeburg, Germany.,Gesundheitscampus Immunologie, Infektiologie und Inflammation (GCI3), Medical Center, Otto-von-Guericke University, Magdeburg, Germany
| | - Subbaiah Chary Nimmagadda
- Department of Hematology and Oncology, Medical Center, Otto-von-Guericke University, Magdeburg, Germany.,Gesundheitscampus Immunologie, Infektiologie und Inflammation (GCI3), Medical Center, Otto-von-Guericke University, Magdeburg, Germany
| | - Peter Müller
- Department of Hematology and Oncology, Medical Center, Otto-von-Guericke University, Magdeburg, Germany.,Gesundheitscampus Immunologie, Infektiologie und Inflammation (GCI3), Medical Center, Otto-von-Guericke University, Magdeburg, Germany
| | - Rüdiger Braun-Dullaeus
- Gesundheitscampus Immunologie, Infektiologie und Inflammation (GCI3), Medical Center, Otto-von-Guericke University, Magdeburg, Germany.,Department of Cardiology and Angiology, Medical Center, Otto-von-Guericke University, Magdeburg, Germany
| | - Juliane Mohr
- Gesundheitscampus Immunologie, Infektiologie und Inflammation (GCI3), Medical Center, Otto-von-Guericke University, Magdeburg, Germany.,Institute of Molecular and Clinical Immunology, and
| | - Denise Wolleschak
- Department of Hematology and Oncology, Medical Center, Otto-von-Guericke University, Magdeburg, Germany.,Gesundheitscampus Immunologie, Infektiologie und Inflammation (GCI3), Medical Center, Otto-von-Guericke University, Magdeburg, Germany
| | - Stefanie Kliche
- Gesundheitscampus Immunologie, Infektiologie und Inflammation (GCI3), Medical Center, Otto-von-Guericke University, Magdeburg, Germany.,Institute of Molecular and Clinical Immunology, and
| | - Holger Amthauer
- Department of Radiology and Nuclear Medicine, University Hospital, Magdeburg, Germany
| | - Florian H Heidel
- Department of Hematology and Oncology, Medical Center, Otto-von-Guericke University, Magdeburg, Germany.,Internal Medicine II, Hematology and Oncology, University Hospital Jena, Jena, Germany.,Leibniz Institute on Aging, Fritz-Lipmann-Institute, Jena, Germany
| | - Burkhart Schraven
- Gesundheitscampus Immunologie, Infektiologie und Inflammation (GCI3), Medical Center, Otto-von-Guericke University, Magdeburg, Germany.,Institute of Molecular and Clinical Immunology, and.,Helmholtz Centre for Infection Research, Department of Immune Control, Braunschweig, Germany
| | - Berend Isermann
- Gesundheitscampus Immunologie, Infektiologie und Inflammation (GCI3), Medical Center, Otto-von-Guericke University, Magdeburg, Germany.,Institute of Clinical Chemistry and Pathobiochemistry
| | - Andreas J Müller
- Gesundheitscampus Immunologie, Infektiologie und Inflammation (GCI3), Medical Center, Otto-von-Guericke University, Magdeburg, Germany.,Institute of Molecular and Clinical Immunology, and.,Helmholtz Centre for Infection Research, Department of Immune Control, Braunschweig, Germany
| | - Thomas Fischer
- Department of Hematology and Oncology, Medical Center, Otto-von-Guericke University, Magdeburg, Germany.,Gesundheitscampus Immunologie, Infektiologie und Inflammation (GCI3), Medical Center, Otto-von-Guericke University, Magdeburg, Germany
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5
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Janapati S, Wurtzel J, Dangelmaier C, Manne BK, Bhavanasi D, Kostyak JC, Kim S, Holinstat M, Kunapuli SP, Goldfinger LE. TC21/RRas2 regulates glycoprotein VI-FcRγ-mediated platelet activation and thrombus stability. J Thromb Haemost 2018; 16:S1538-7836(22)02217-6. [PMID: 29883056 PMCID: PMC6286703 DOI: 10.1111/jth.14197] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Indexed: 12/27/2022]
Abstract
Essentials RAS proteins are expressed in platelets but their functions are largely uncharacterized. TC21/RRas2 is required for glycoprotein VI-induced platelet responses and for thrombus stability in vivo. TC21 regulates platelet aggregation by control of αIIb β3 integrin activation, via crosstalk with Rap1b. This is the first indication of functional importance of a proto-oncogenic RAS protein in platelets. SUMMARY Background Many RAS family small GTPases are expressed in platelets, including RAC, RHOA, RAP, and HRAS/NRAS/RRAS1, but most of their signaling and cellular functions remain poorly understood. Like RRAS1, TC21/RRAS2 reverses HRAS-induced suppression of integrin activation in CHO cells. However, a role for TC21 in platelets has not been explored. Objectives To determine TC21 expression in platelets, TC21 activation in response to platelet agonists, and roles of TC21 in platelet function in in vitro and in vivo thrombosis. Results We demonstrate that TC21 is expressed in human and murine platelets, and is activated in response to agonists for the glycoprotein (GP) VI-FcRγ immunoreceptor tyrosine-based activation motif (ITAM)-containing collagen receptor, in an Src-dependent manner. GPVI-induced platelet aggregation, integrin αIIb β3 activation, and α-granule and dense granule secretion, as well as phosphorylation of Syk, phospholipase Cγ2, AKT, and extracellular signal-regulated kinase, were inhibited in TC21-deficient platelets ex vivo. In contrast, these responses were normal in TC21-deficient platelets following stimulation with P2Y, protease-activated receptor 4 and C-type lectin receptor 2 receptor agonists, indicating that the function of TC21 in platelets is GPVI-FcRγ-ITAM-specific. TC21 was required for GPVI-induced activation of Rap1b. TC21-deficient mice did not show a significant delay in injury-induced thrombosis as compared with wild-type controls; however, thrombi were unstable. Hemostatic responses showed similar effects. Conclusions TC21 is essential for GPVI-FcRγ-mediated platelet activation and for thrombus stability in vivo via control of Rap1b and integrins.
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Affiliation(s)
- S Janapati
- The Sol Sherry Thrombosis Research Center and Department of Pharmacology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - J Wurtzel
- The Sol Sherry Thrombosis Research Center and Department of Anatomy & Cell Biology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - C Dangelmaier
- The Sol Sherry Thrombosis Research Center and Department of Pharmacology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - B K Manne
- The Sol Sherry Thrombosis Research Center and Department of Pharmacology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - D Bhavanasi
- The Sol Sherry Thrombosis Research Center and Department of Pharmacology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - J C Kostyak
- The Sol Sherry Thrombosis Research Center and Department of Pharmacology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - S Kim
- The Sol Sherry Thrombosis Research Center and Department of Pharmacology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - M Holinstat
- Department of Pharmacology, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI, USA
| | - S P Kunapuli
- The Sol Sherry Thrombosis Research Center and Department of Pharmacology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - L E Goldfinger
- The Sol Sherry Thrombosis Research Center and Department of Anatomy & Cell Biology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
- Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, PA, USA
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6
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Sequera C, Manzano S, Guerrero C, Porras A. How Rap and its GEFs control liver physiology and cancer development. C3G alterations in human hepatocarcinoma. Hepat Oncol 2018; 5:HEP05. [PMID: 30302196 PMCID: PMC6168044 DOI: 10.2217/hep-2017-0026] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 03/20/2018] [Indexed: 02/08/2023] Open
Abstract
Rap proteins regulate liver physiopathology. For example, Rap2B promotes hepatocarcinoma (HCC) growth, while Rap1 might play a dual role. The RapGEF, Epac1, activates Rap upon cAMP binding, regulating metabolism, survival, and liver regeneration. A liver specific Epac2 isoform lacking cAMP-binding domain also activates Rap1, promoting fibrosis in alcoholic liver disease. C3G (RapGEF1) is also present in the liver, but mainly as shorter isoforms. Its function in the liver remains unknown. Information from different public genetic databases revealed that C3G mRNA levels increase in HCC, although they decrease in metastatic stages. In addition, several mutations in RapGEF1 gene are present, associated with a reduced patient survival. Based on this, C3G might represent a new HCC diagnostic and prognostic marker, and a therapeutic target.
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Affiliation(s)
- Celia Sequera
- Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain.,Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
| | - Sara Manzano
- Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain.,Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
| | - Carmen Guerrero
- Instituto de Biología Molecular y Celular del Cáncer, USAL-CSIC, Salamanca, Spain.,Instituto de Investigación Biomédica de Salamanca (IBSAL), Salamanca, Spain.,Departamento de Medicina, Universidad de Salamanca, Salamanca, Spain.,Instituto de Biología Molecular y Celular del Cáncer, USAL-CSIC, Salamanca, Spain.,Instituto de Investigación Biomédica de Salamanca (IBSAL), Salamanca, Spain.,Departamento de Medicina, Universidad de Salamanca, Salamanca, Spain
| | - Almudena Porras
- Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain.,Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
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7
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Umezawa Y, Akiyama H, Okada K, Ishida S, Nogami A, Oshikawa G, Kurosu T, Miura O. Molecular mechanisms for enhancement of stromal cell-derived factor 1-induced chemotaxis by platelet endothelial cell adhesion molecule 1 (PECAM-1). J Biol Chem 2017; 292:19639-19655. [PMID: 28974577 DOI: 10.1074/jbc.m117.779603] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 09/26/2017] [Indexed: 01/16/2023] Open
Abstract
Platelet endothelial cell adhesion molecule 1 (PECAM-1) is a cell adhesion protein involved in the regulation of cell adhesion and migration. Interestingly, several PECAM-1-deficient hematopoietic cells exhibit impaired chemotactic responses to stromal cell-derived factor 1 (SDF-1), a chemokine essential for B lymphopoiesis and bone marrow myelopoiesis. However, whether PECAM-1 is involved in SDF-1-regulated chemotaxis is unknown. We report here that SDF-1 induces tyrosine phosphorylation of PECAM-1 at its immunoreceptor tyrosine-based inhibition motifs in several hematopoietic cell lines via the Src family kinase Lyn, Bruton's tyrosine kinase, and JAK2 and that inhibition of these kinases reduced chemotaxis. Overexpression and knockdown of PECAM-1 enhanced and down-regulated, respectively, SDF-1-induced Gαi-dependent activation of the PI3K/Akt/mTORC1 pathway and small GTPase Rap1 in hematopoietic 32Dcl3 cells, and these changes in activation correlated with chemotaxis. Furthermore, pharmacological or genetic inhibition of the PI3K/Akt/mTORC1 pathway or Rap1, respectively, revealed that these pathways are independently activated and required for SDF-1-induced chemotaxis. When coexpressed in 293T cells, PECAM-1 physically associated with the SDF-1 receptor CXCR4. Moreover, PECAM-1 overexpression and knockdown reduced and enhanced SDF-1-induced endocytosis of CXCR4, respectively. Furthermore, when expressed in 32Dcl3 cells, an endocytosis-defective CXCR4 mutant, CXCR4-S324A/S325A, could activate the PI3K/Akt/mTORC1 pathway as well as Rap1 and induce chemotaxis in a manner similar to PECAM-1 overexpression. These findings suggest that PECAM-1 enhances SDF-1-induced chemotaxis by augmenting and prolonging activation of the PI3K/Akt/mTORC1 pathway and Rap1 and that PECAM-1, at least partly, exerts its activity by inhibiting SDF-1-induced internalization of CXCR4.
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Affiliation(s)
- Yoshihiro Umezawa
- From the Department of Hematology, Graduate School of Medical and Dental Sciences Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyoku, Tokyo 113-8519, Japan
| | - Hiroki Akiyama
- From the Department of Hematology, Graduate School of Medical and Dental Sciences Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyoku, Tokyo 113-8519, Japan
| | - Keigo Okada
- From the Department of Hematology, Graduate School of Medical and Dental Sciences Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyoku, Tokyo 113-8519, Japan
| | - Shinya Ishida
- From the Department of Hematology, Graduate School of Medical and Dental Sciences Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyoku, Tokyo 113-8519, Japan
| | - Ayako Nogami
- From the Department of Hematology, Graduate School of Medical and Dental Sciences Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyoku, Tokyo 113-8519, Japan
| | - Gaku Oshikawa
- From the Department of Hematology, Graduate School of Medical and Dental Sciences Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyoku, Tokyo 113-8519, Japan
| | - Tetsuya Kurosu
- From the Department of Hematology, Graduate School of Medical and Dental Sciences Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyoku, Tokyo 113-8519, Japan
| | - Osamu Miura
- From the Department of Hematology, Graduate School of Medical and Dental Sciences Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyoku, Tokyo 113-8519, Japan
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8
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Mazel T. Crosstalk of cell polarity signaling pathways. PROTOPLASMA 2017; 254:1241-1258. [PMID: 28293820 DOI: 10.1007/s00709-017-1075-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 01/02/2017] [Indexed: 06/06/2023]
Abstract
Cell polarity, the asymmetric organization of cellular components along one or multiple axes, is present in most cells. From budding yeast cell polarization induced by pheromone signaling, oocyte polarization at fertilization to polarized epithelia and neuronal cells in multicellular organisms, similar mechanisms are used to determine cell polarity. Crucial role in this process is played by signaling lipid molecules, small Rho family GTPases and Par proteins. All these signaling circuits finally govern the cytoskeleton, which is responsible for oriented cell migration, cell shape changes, and polarized membrane and organelle trafficking. Thus, typically in the process of cell polarization, most cellular constituents become polarized, including plasma membrane lipid composition, ion concentrations, membrane receptors, and proteins in general, mRNA, vesicle trafficking, or intracellular organelles. This review gives a brief overview how these systems talk to each other both during initial symmetry breaking and within the signaling feedback loop mechanisms used to preserve the polarized state.
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Affiliation(s)
- Tomáš Mazel
- Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, Albertov 4, 128 00, Prague 2, Czech Republic.
- State Institute for Drug Control, Šrobárova 48, 100 41, Prague 10, Czech Republic.
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9
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JAK2-V617F activates β1-integrin-mediated adhesion of granulocytes to vascular cell adhesion molecule 1. Leukemia 2017; 31:1223-1226. [PMID: 28096537 PMCID: PMC5420787 DOI: 10.1038/leu.2017.26] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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10
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The Rap1-RIAM-talin axis of integrin activation and blood cell function. Blood 2016; 128:479-87. [PMID: 27207789 DOI: 10.1182/blood-2015-12-638700] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 05/07/2016] [Indexed: 12/14/2022] Open
Abstract
Integrin adhesion receptors mediate the adhesion of blood cells, such as leukocytes, to other cells, such as endothelial cells. Integrins also are critical for anchorage of hematopoietic precursors to the extracellular matrix. Blood cells can dynamically regulate the affinities of integrins for their ligands ("activation"), an event central to their functions. Here we review recent progress in understanding the mechanisms of integrin activation with a focus on the functions of blood cells. We discuss how talin binding to the integrin β cytoplasmic domain, in conjunction with the plasma membrane, induces long-range allosteric rearrangements that lead to integrin activation. Second, we review our understanding of how signaling events, particularly those involving Rap1 small guanosine triphosphate (GTP)hydrolases, can regulate the talin-integrin interaction and resulting activation. Third, we review recent findings that highlight the role of the Rap1-GTP-interacting adapter molecule (RIAM), encoded by the APBB1IP gene, in leukocyte integrin activation and consequently in leukocyte trafficking.
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11
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Magliozzi R, Low TY, Weijts BGMW, Cheng T, Spanjaard E, Mohammed S, van Veen A, Ovaa H, de Rooij J, Zwartkruis FJT, Bos JL, de Bruin A, Heck AJR, Guardavaccaro D. Control of epithelial cell migration and invasion by the IKKβ- and CK1α-mediated degradation of RAPGEF2. Dev Cell 2013; 27:574-85. [PMID: 24290981 DOI: 10.1016/j.devcel.2013.10.023] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 10/04/2013] [Accepted: 10/29/2013] [Indexed: 10/26/2022]
Abstract
Epithelial cell migration is crucial for the development and regeneration of epithelial tissues. Aberrant regulation of epithelial cell migration has a major role in pathological processes such as the development of cancer metastasis and tissue fibrosis. Here, we report that in response to factors that promote cell motility, the Rap guanine exchange factor RAPGEF2 is rapidly phosphorylated by I-kappa-B-kinase-β and casein kinase-1α and consequently degraded by the proteasome via the SCF(βTrCP) ubiquitin ligase. Failure to degrade RAPGEF2 in epithelial cells results in sustained activity of Rap1 and inhibition of cell migration induced by HGF, a potent metastatic factor. Furthermore, expression of a degradation-resistant RAPGEF2 mutant greatly suppresses dissemination and metastasis of human breast cancer cells. These findings reveal a molecular mechanism regulating migration and invasion of epithelial cells and establish a key direct link between IKKβ and cell motility controlled by Rap-integrin signaling.
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Affiliation(s)
- Roberto Magliozzi
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Teck Yew Low
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands; The Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Bart G M W Weijts
- Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands
| | - Tianhong Cheng
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Emma Spanjaard
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Shabaz Mohammed
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands; The Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Anouk van Veen
- Department of Physiological Chemistry and Center for Biomedical Genetics, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - Huib Ovaa
- Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Johan de Rooij
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Fried J T Zwartkruis
- Department of Physiological Chemistry and Center for Biomedical Genetics, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - Johannes L Bos
- Department of Physiological Chemistry and Center for Biomedical Genetics, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - Alain de Bruin
- Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands
| | - Albert J R Heck
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands; The Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Daniele Guardavaccaro
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands.
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12
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JAK2V617F activates Lu/BCAM-mediated red cell adhesion in polycythemia vera through an EpoR-independent Rap1/Akt pathway. Blood 2013; 121:658-65. [DOI: 10.1182/blood-2012-07-440487] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Abstract
Polycythemia vera (PV) is characterized by an increased RBC mass, spontaneous erythroid colony formation, and the JAK2V617F mutation. PV is associated with a high risk of mesenteric and cerebral thrombosis. PV RBC adhesion to endothelial laminin is increased and mediated by phosphorylated erythroid Lu/BCAM. In the present work, we investigated the mechanism responsible for Lu/BCAM phosphorylation in the presence of JAK2V617F using HEL and BaF3 cell lines as well as RBCs from patients with PV. High levels of Rap1-GTP were found in HEL and BaF3 cells expressing JAK2V617F compared with BaF3 cells with wild-type JAK2. This finding was associated with increased Akt activity, Lu/BCAM phosphorylation, and cell adhesion to laminin that were inhibited by the dominant-negative Rap1S17N or by the specific Rap1 inhibitor GGTI-298. Surprisingly, knocking-down EpoR in HEL cells did not alter Akt activity or cell adhesion to laminin. Our findings reveal a novel EpoR-independent Rap1/Akt signaling pathway that is activated by JAK2V617F in circulating PV RBCs and responsible for Lu/BCAM activation. This new characteristic of JAK2V617F could play a critical role in initiating abnormal interactions among circulating and endothelial cells in patients with PV.
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13
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Wu N, Kurosu T, Oshikawa G, Nagao T, Miura O. PECAM-1 is involved in BCR/ABL signaling and may downregulate imatinib-induced apoptosis of Philadelphia chromosome-positive leukemia cells. Int J Oncol 2012; 42:419-28. [PMID: 23233201 PMCID: PMC3583636 DOI: 10.3892/ijo.2012.1729] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Accepted: 11/16/2012] [Indexed: 01/10/2023] Open
Abstract
PECAM-1 (CD31) is an immunoreceptor tyrosine-based inhibitory motif (ITIM)-containing surface glycoprotein expressed on various hematopoietic cells as well as on endothelial cells. PECAM-1 has been shown to play roles in regulation of adhesion, migration and apoptosis. The BCR/ABL fusion tyrosine kinase is expressed in chronic myeloid leukemia and Philadelphia-positive (Ph+) acute lymphoblastic leukemia cells, and its inhibition by the clinically used tyrosine kinase inhibitors imatinib or dasatinib induces apoptosis of these cells. In the present study, we demonstrate that PECAM-1 is tyrosine phospho rylated in its ITIM motifs in various BCR/ABL-expressing cells including primary leukemia cells. Studies using imatinib and dasatinib as well as transient expression experiments in 293T cells revealed that PECAM-1 was phosphorylated directly by BCR/ABL, which was enhanced by the imatinib-resistant E255K and T315I mutations, or partly by the Src family tyrosine kinases, including Lyn, which were activated dependently or independently on BCR/ABL. We also demonstrate by using a substrate trapping mutant of SHP2 that tyrosine phosphorylated PECAM-1 binds SHP2 and is a major substrate for this tyrosine phosphatase in BCR/ABL-expressing cells. Overexpression of PECAM-1 in BCR/ABL-expressing cells, including K562 human leukemia cells, enhanced cell adhesion and partially inhibited imatinib-induced apoptosis involving mitochondria depolarization and caspase-3 cleavage, at least partly, in an ITIM-independent manner. These data suggest that PECAM-1 may play a role in regulation of apoptosis as well as adhesion of BCR/ABL-expressing cells to modulate their imatinib sensitivity and would be a possible candidate for therapeutic target in Ph+ leukemias.
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Affiliation(s)
- Nan Wu
- Department of Hematology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyoku, Tokyo 113-8519, Japan
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14
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Liu L, Aerbajinai W, Ahmed SM, Rodgers GP, Angers S, Parent CA. Radil controls neutrophil adhesion and motility through β2-integrin activation. Mol Biol Cell 2012; 23:4751-65. [PMID: 23097489 PMCID: PMC3521683 DOI: 10.1091/mbc.e12-05-0408] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Various agonists trigger β2-integrin activation in neutrophils, yet the mechanisms that regulate β2-integrin inside-out signaling remain obscure. Radil, a novel Rap downstream effector, is an important adapter in the pathway that links G protein–coupled chemoattractant receptors to adhesion complexes during neutrophil chemotaxis. Integrin activation is required to facilitate multiple adhesion-dependent functions of neutrophils, such as chemotaxis, which is critical for inflammatory responses to injury and pathogens. However, little is known about the mechanisms that mediate integrin activation in neutrophils. We show that Radil, a novel Rap1 effector, regulates β1- and β2-integrin activation and controls neutrophil chemotaxis. On activation and chemotactic migration of neutrophils, Radil quickly translocates from the cytoplasm to the plasma membrane in a Rap1a-GTP–dependent manner. Cells overexpressing Radil show a substantial increase in cell adhesion, as well as in integrin/focal adhesion kinase (FAK) activation, and exhibit an elongated morphology, with severe tail retraction defects. This phenotype is effectively rescued by treatment with either β2-integrin inhibitory antibodies or FAK inhibitors. Conversely, knockdown of Radil causes severe inhibition of cell adhesion, β2-integrin activation, and chemotaxis. Furthermore, we found that inhibition of Rap activity by RapGAP coexpression inhibits Radil-mediated integrin and FAK activation, decreases cell adhesion, and abrogates the long-tail phenotype of Radil cells. Overall, these studies establish that Radil regulates neutrophil adhesion and motility by linking Rap1 to β2-integrin activation.
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Affiliation(s)
- Lunhua Liu
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
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15
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Zhang G, Xiang B, Ye S, Chrzanowska-Wodnicka M, Morris AJ, Gartner TK, Whiteheart SW, White GC, Smyth SS, Li Z. Distinct roles for Rap1b protein in platelet secretion and integrin αIIbβ3 outside-in signaling. J Biol Chem 2011; 286:39466-77. [PMID: 21940635 DOI: 10.1074/jbc.m111.239608] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Rap1b is activated by platelet agonists and plays a critical role in integrin α(IIb)β(3) inside-out signaling and platelet aggregation. Here we show that agonist-induced Rap1b activation plays an important role in stimulating secretion of platelet granules. We also show that α(IIb)β(3) outside-in signaling can activate Rap1b, and integrin outside-in signaling-mediated Rap1b activation is important in facilitating platelet spreading on fibrinogen and clot retraction. Rap1b-deficient platelets had diminished ATP secretion and P-selectin expression induced by thrombin or collagen. Importantly, addition of low doses of ADP and/or fibrinogen restored aggregation of Rap1b-deficient platelets. Furthermore, we found that Rap1b was activated by platelet spreading on immobilized fibrinogen, a process that was not affected by P2Y(12) or TXA(2) receptor deficiency, but was inhibited by the selective Src inhibitor PP2, the PKC inhibitor Ro-31-8220, or the calcium chelator demethyl-1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis. Clot retraction was abolished, and platelet spreading on fibrinogen was diminished in Rap1b-deficient platelets compared with wild-type controls. The defects in clot retraction and spreading on fibrinogen of Rap1b-deficient platelets were not rescued by addition of MnCl(2), which elicits α(IIb)β(3) outside-in signaling in the absence of inside-out signaling. Thus, our results reveal two different activation mechanisms of Rap1b as well as novel functions of Rap1b in platelet secretion and in integrin α(IIb)β(3) outside-in signaling.
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Affiliation(s)
- Guoying Zhang
- Division of Cardiovascular Medicine, The Gill Heart Institute, University of Kentucky, Lexington, Kentucky 40536, USA
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16
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Signalling to actin: role of C3G, a multitasking guanine-nucleotide-exchange factor. Biosci Rep 2011; 31:231-44. [PMID: 21366540 DOI: 10.1042/bsr20100094] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
C3G (Crk SH3-domain-binding guanine-nucleotide-releasing factor) is a ubiquitously expressed member of a class of molecules called GEFs (guanine-nucleotide-exchange factor) that activate small GTPases and is involved in pathways triggered by a variety of signals. It is essential for mammalian embryonic development and many cellular functions in adult tissues. C3G participates in regulating functions that require cytoskeletal remodelling such as adhesion, migration, maintenance of cell junctions, neurite growth and vesicle traffic. C3G is spatially and temporally regulated to act on Ras family GTPases Rap1, Rap2, R-Ras, TC21 and Rho family member TC10. Increased C3G protein levels are associated with differentiation of various cell types, indicating an important role for C3G in cellular differentiation. In signalling pathways, C3G serves functions dependent on catalytic activity as well as protein interaction and can therefore integrate signals necessary for the execution of more than one cellular function. This review summarizes our current knowledge of the biology of C3G with emphasis on its role as a transducer of signals to the actin cytoskeleton. Deregulated C3G may also contribute to pathogenesis of human disorders and therefore could be a potential therapeutic target.
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17
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Weigel-Van Aken KAK. Pharmacological activation of guanine nucleotide exchange factors for the small GTPase Rap1 recruits high-affinity beta1 integrins as coreceptors for parvovirus B19: improved ex vivo gene transfer to human erythroid progenitor cells. Hum Gene Ther 2010; 20:1665-78. [PMID: 19702438 DOI: 10.1089/hum.2009.123] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Parvovirus B19 has potential as a gene therapy vector because of its restricted tropism for human erythroid progenitor cells in the bone marrow. B19 binds to the cell surface through P antigen and we identified activated beta(1) integrins as coreceptors for internalization. Because differentiation with phorbol ester induces beta(1) integrin coreceptor activity, but cell differentiation is not desirable in gene transfer to human progenitor cells and one of the downstream effectors of phorbol esters is the small GTPase Rap1, the role of Rap1 in the recruitment of beta(1) integrins on hematopoietic cells was examined. Expression of a constitutively active Rap1 (63E) was sufficient to recruit beta(1) integrin coreceptors in erythroleukemic K562 cells by inducing high-affinity integrin conformation. A crucial role of actin polymerization in Rap1-mediated beta(1) integrin recruitment was documented by complete inhibition of the 63E Rap1 effect with low-dose cytochalasin D and by the ability of a constitutively active mutant of the actin cytoskeleton regulator Rac1 to sensitize K562 cells to the pharmacological activation of endogenous Rap1, using the Rap1 exchange factor-specific 8-pCPT-2'-O-Me-cAMP [8-(4-chlorophenylthio)-2'-O-methyladenosine-3',5'-cyclic monophosphate]. Interestingly, in primary human erythroid progenitor cells, 8-pCPT-2'-O-Me-cAMP was sufficient to significantly increase B19-mediated gene transfer, suggesting that these cells possess the cytoskeleton organization capacity required for efficient recruitment of beta(1) integrins by brief pharmacological stimulation of Rap1 GTP loading. Because 8-pCPT-2'-O-Me-cAMP has been implicated in enhanced homing of progenitor cells, these results identify a novel tool with which to optimize ex vivo B19-mediated gene transfer and potentially improve homing of transduced cells by Rap1-beta(1) integrin activation with 8-pCPT-2'-O-Me-cAMP.
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Affiliation(s)
- Kirsten A K Weigel-Van Aken
- Division of Cellular and Molecular Therapy, Department of Pediatrics, Powell Gene Therapy Center, University of Florida College of Medicine, Gainesville, FL 32610, USA.
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18
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Yassin ER, Sarma NJ, Abdul-Nabi AM, Dombrowski J, Han Y, Takeda A, Yaseen NR. Dissection of the transformation of primary human hematopoietic cells by the oncogene NUP98-HOXA9. PLoS One 2009; 4:e6719. [PMID: 19696924 PMCID: PMC2725295 DOI: 10.1371/journal.pone.0006719] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2009] [Accepted: 07/28/2009] [Indexed: 11/18/2022] Open
Abstract
NUP98-HOXA9 is the prototype of a group of oncoproteins associated with acute myeloid leukemia. It consists of an N-terminal portion of NUP98 fused to the homeodomain of HOXA9 and is believed to act as an aberrant transcription factor that binds DNA through the homeodomain. Here we show that NUP98-HOXA9 can regulate transcription without binding to DNA. In order to determine the relative contributions of the NUP98 and HOXA9 portions to the transforming ability of NUP98-HOXA9, the effects of NUP98-HOXA9 on primary human CD34+ cells were dissected and compared to those of wild-type HOXA9. In contrast to previous findings in mouse cells, HOXA9 had only mild effects on the differentiation and proliferation of primary human hematopoietic cells. The ability of NUP98-HOXA9 to disrupt the differentiation of primary human CD34+ cells was found to depend primarily on the NUP98 portion, whereas induction of long-term proliferation required both the NUP98 moiety and an intact homeodomain. Using oligonucleotide microarrays in primary human CD34+ cells, a group of genes was identified whose dysregulation by NUP98-HOXA9 is attributable primarily to the NUP98 portion. These include RAP1A, HEY1, and PTGS2 (COX-2). Their functions may reflect the contribution of the NUP98 moiety of NUP98-HOXA9 to leukemic transformation. Taken together, these results suggest that the effects of NUP98-HOXA9 on gene transcription and cell transformation are mediated by at least two distinct mechanisms: one that involves promoter binding through the homeodomain with direct transcriptional activation, and another that depends predominantly on the NUP98 moiety and does not involve direct DNA binding.
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Affiliation(s)
- Enas R. Yassin
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Nayan J. Sarma
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Anmaar M. Abdul-Nabi
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - James Dombrowski
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Ye Han
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Akiko Takeda
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Nabeel R. Yaseen
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
- * E-mail:
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19
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Dao VT, Dupuy AG, Gavet O, Caron E, de Gunzburg J. Dynamic changes in Rap1 activity are required for cell retraction and spreading during mitosis. J Cell Sci 2009; 122:2996-3004. [PMID: 19638416 DOI: 10.1242/jcs.041301] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
At the onset of mitosis, most adherent cells undergo cell retraction characterised by the disassembly of focal adhesions and actin stress fibres. Mitosis takes place in rounded cells, and the two daughter cells spread again after cytokinesis. Because of the well-documented ability of the small GTPase Rap1 to stimulate integrin-dependent adhesion and spreading, we assessed its role during mitosis. We show that Rap1 activity is regulated during this process. Changes in Rap1 activity play an essential role in regulating cell retraction and spreading, respectively, before and after mitosis of HeLa cells. Indeed, endogenous Rap1 is inhibited at the onset of mitosis; conversely, constitutive activation of Rap1 inhibits the disassembly of premitotic focal adhesions and of the actin cytoskeleton, leading to delayed mitosis and to cytokinesis defects. Rap1 activity slowly increases after mitosis ends; inhibition of Rap1 activation by the ectopic expression of the dominant-negative Rap1[S17A] mutant prevents the rounded cells from spreading after mitosis. For the first time, we provide evidence for the direct regulation of adhesion processes during mitosis via the activity of the Rap1 GTPase.
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Affiliation(s)
- Vi Thuy Dao
- Institut Curie, Centre de Recherche, Inserm U528, 26 rue d'Ulm, 75248 Paris, France
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20
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Severson EA, Parkos CA. Structural determinants of Junctional Adhesion Molecule A (JAM-A) function and mechanisms of intracellular signaling. Curr Opin Cell Biol 2009; 21:701-7. [PMID: 19608396 DOI: 10.1016/j.ceb.2009.06.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Revised: 06/01/2009] [Accepted: 06/17/2009] [Indexed: 10/20/2022]
Abstract
Junctional Adhesion Molecule A (JAM-A) is a multifunctional cell surface protein that has multiple evolutionarily conserved structural features. There is now conclusive evidence that discrete structural elements on JAM-A mediate intracellular signaling events that alter cell migration and paracellular permeability. Specifically, self-dimerization between extracellular Ig-like loops and close apposition of PDZ-dependent, JAM-A-associated intracellular scaffold proteins such as Afadin and guanine-nucleotide exchange factors mediate activation of Rap1 and modulation of epithelial cell migration by effects on beta1 integrin. While the same JAM-A structural features also modulate migration of other cell types and paracellular permeability in epithelia/endothelia, additional signaling proteins/mechanisms are probably involved. Recent insights into JAM-A outside-in signaling events that regulate these cellular functions are discussed.
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Affiliation(s)
- Eric A Severson
- Department of Pathology and Laboratory Medicine, Emory University, 615 Michael Street, Atlanta, GA 30322, USA
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21
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Borland G, Smith BO, Yarwood SJ. EPAC proteins transduce diverse cellular actions of cAMP. Br J Pharmacol 2009; 158:70-86. [PMID: 19210747 DOI: 10.1111/j.1476-5381.2008.00087.x] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
It has now been over 10 years since efforts to completely understand the signalling actions of cAMP (3'-5'-cyclic adenosine monophosphate) led to the discovery of exchange protein directly activated by cAMP (EPAC) proteins. In the current review we will highlight important advances in the understanding of EPAC structure and function and demonstrate that EPAC proteins mediate multiple actions of cAMP in cells, revealing future targets for pharmaceutical intervention. It has been known for some time that drugs that elevate intracellular cAMP levels have proven therapeutic benefit for diseases ranging from depression to inflammation. The challenge now is to determine which of these positive actions of cAMP involve activation of EPAC-regulated signal transduction pathways. EPACs are specific guanine nucleotide exchange factors for the Ras GTPase homologues, Rap1 and Rap2, which they activate independently of the classical routes for cAMP signalling, cyclic nucleotide-gated ion channels and protein kinase A. Rather, EPAC activation is triggered by internal conformational changes induced by direct interaction with cAMP. Leading from this has been the development of EPAC-specific agonists, which has helped to delineate numerous cellular actions of cAMP that rely on subsequent activation of EPAC. These include regulation of exocytosis and the control of cell adhesion, growth, division and differentiation. Recent work also implicates EPAC in the regulation of anti-inflammatory signalling in the vascular endothelium, namely negative regulation of pro-inflammatory cytokine signalling and positive support of barrier function. Further elucidation of these important signalling mechanisms will no doubt support the development of the next generation of anti-inflammatory drugs.
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Affiliation(s)
- Gillian Borland
- Division of Molecular and Cellular Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow, UK
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22
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Role of the small GTPase Rap1 for integrin activity regulation in endothelial cells and angiogenesis. Blood 2009; 113:488-97. [DOI: 10.1182/blood-2008-02-138438] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Abstract
Ras-associated protein 1 (Rap1), a small GTPase, attracted attention because of its involvement in several aspects of cell adhesion, including integrin- and cadherin-mediated adhesion. Yet, the role of Rap1 genes and of Rap1 effectors for angiogenesis has not been investigated. Human umbilical vein endothelial cells (HUVECs) express Rap1a and Rap1b mRNA. To determine the contribution of Rap1 activity for angiogenesis, we overexpressed Rap1GAP1, a GTPase-activating protein that inhibits Rap1 activity. Overexpression of Rap1GAP1 significantly blocked angiogenic sprouting and tube-forming activity of HUVECs as well as migration and integrin-dependent adhesion. Silencing of Rap1a, Rap1b, or both significantly blocked HUVECs sprouting under basal and basic fibroblast growth factor-stimulated conditions and reduced HUVEC migration and integrin-dependent adhesion. We found that Rap1a and Rap1b are essential for the conformational activation of β1-integrins in endothelial cells. Furthermore, silencing of Rap1a and Rap1b prevented phosphorylation of tyrosine 397 in focal adhesion kinase (FAK) and vascular endothelial growth factor-induced Akt1-activation. Rap1a−/−-deficient and Rap1a+/− heterozygote mice displayed reduced neovascularization after hind limb ischemia compared with wild-type mice. Silencing of RAPL significantly blocked the Rap1-induced sprouting of HUVECs, suggesting that the angiogenic activity of Rap1 is partly mediated by RAPL. Our data demonstrate a critical role of Rap1 in the regulation of β1-integrin affinity, adhesion, and migration in endothelial cells and in postnatal neovascularization.
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Voss AK, Britto JM, Dixon MP, Sheikh BN, Collin C, Tan SS, Thomas T. C3G regulates cortical neuron migration, preplate splitting and radial glial cell attachment. Development 2008; 135:2139-49. [PMID: 18506028 DOI: 10.1242/dev.016725] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Neuronal migration is integral to the development of the cerebral cortex and higher brain function. Cortical neuron migration defects lead to mental disorders such as lissencephaly and epilepsy. Interaction of neurons with their extracellular environment regulates cortical neuron migration through cell surface receptors. However, it is unclear how the signals from extracellular matrix proteins are transduced intracellularly. We report here that mouse embryos lacking the Ras family guanine nucleotide exchange factor, C3G (Rapgef1, Grf2), exhibit a cortical neuron migration defect resulting in a failure to split the preplate into marginal zone and subplate and a failure to form a cortical plate. C3G-deficient cortical neurons fail to migrate. Instead, they arrest in a multipolar state and accumulate below the preplate. The basement membrane is disrupted and radial glial processes are disorganised and lack attachment in C3G-deficient brains. C3G is activated in response to reelin in cortical neurons, which, in turn, leads to activation of the small GTPase Rap1. In C3G-deficient cells, Rap1 GTP loading in response to reelin stimulation is reduced. In conclusion, the Ras family regulator C3G is essential for two aspects of cortex development, namely radial glial attachment and neuronal migration.
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Affiliation(s)
- Anne K Voss
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3050, Australia.
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24
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Ulfman LH, Kamp VM, van Aalst CW, Verhagen LP, Sanders ME, Reedquist KA, Buitenhuis M, Koenderman L. Homeostatic intracellular-free Ca2+ is permissive for Rap1-mediated constitutive activation of alpha4 integrins on eosinophils. THE JOURNAL OF IMMUNOLOGY 2008; 180:5512-9. [PMID: 18390735 DOI: 10.4049/jimmunol.180.8.5512] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Although much progress has been made in understanding the molecular mechanisms underlying agonist-induced "inside-out" activation of integrins, little is known about how basal levels of integrin function are maintained. This is particularly important for nonactivated eosinophils, where intermediate activation of alpha(4)beta(1) integrin supports recruitment to endothelial cells under flow conditions. Depletion of intracellular Ca(2+) and pharmacological inhibition of phospholipase C (but not other intracellular signaling molecules, including PI3K, ERK1/2, p38 MAPK, and tyrosine kinase activity) abrogated basal alpha(4) integrin activity in nonactivated eosinophils. Basal alpha(4) integrin activation was associated with activation of the small GTPase Rap1, a known regulator of agonist-induced integrin function. Basal Rap activation was dependent upon phospholipase C, but not intracellular Ca(2+). However, depletion of intracellular Ca(2+) in CD34(+) hematopoietic progenitor cells abolished RapV12-mediated induction of alpha(4) integrin activity. Thus, residual Rap activity or constitutively active Rap activity in Ca(2+)-depleted cells is not sufficient to induce alpha(4) integrin activation. These data suggest that activation of functional alpha(4) integrin activity in resting eosinophils is mediated by Rap1 provided that the intracellular-free Ca(2+) is at a normal homeostatic concentration.
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Affiliation(s)
- Laurien H Ulfman
- Department of Respiratory Medicine, University Medical Center Utrecht, Utrecht, The Netherlands.
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25
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Hamadmad SN, Hohl RJ. Erythropoietin stimulates cancer cell migration and activates RhoA protein through a mitogen-activated protein kinase/extracellular signal-regulated kinase-dependent mechanism. J Pharmacol Exp Ther 2007; 324:1227-33. [PMID: 18079357 DOI: 10.1124/jpet.107.129643] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Erythropoietin (Epo) receptor (EpoR) is expressed in several cancer cell lines, and the functional consequence of this expression is under extensive study. In this study, we used a cervical cancer cell line in which EpoR was first found to be expressed and to correlate with the severity of the disease. We demonstrate that Epo is a chemoattractant for these cancer cells, enhancing their migration under serum-starved conditions. Using a Transwell migration system, we show that Epo enhances cancer cell migration in a dose- and time-dependent manner. The effect of Epo is dependent on the activity of two signaling pathways: the mitogen-activated protein kinase (MAPK) pathway and the RhoA GTPase pathway. We show that Epo activates both pathways in a Janus kinase-dependent manner and that this activation is required for Epo effects on cell migration. Furthermore, we use both pharmacological and genetic inhibitors to demonstrate that the activation of RhoA GTPase is dependent on the activity of the MAPK pathway, providing the first evidence for interaction between these two signaling cascades.
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Affiliation(s)
- Sumaya N Hamadmad
- Department of Internal Medicine, SE 313 GH, University of Iowa, Iowa City, IA 52242, USA
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Lafuente EM, Iwamoto Y, Carman CV, van Puijenbroek AAFL, Constantine E, Li L, Boussiotis VA. Active Rap1, a small GTPase that induces malignant transformation of hematopoietic progenitors, localizes in the nucleus and regulates protein expression. Leuk Lymphoma 2007; 48:987-1002. [PMID: 17487743 DOI: 10.1080/10428190701242341] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Rap1, a member of the Ras superfamily, regulates cytoskeletal changes in lower eukaryots and integrin-mediated adhesion in hematopoietic cells. Sustained activation of Rap1 in mouse hematopoietic stem cells causes expansion of hematopoietic progenitors, followed by a myeloproliferative disorder mimicking chronic myeloid leukemia. Moreover, these mice develop a B-cell lymphoproliferative disorder resembling chronic lymphocytic leukemia. Here, we used HEK 293 cells as a tool to examine the molecular effects of Rap1. We observed that a constitutively active Rap1 mutant localized predominantly in the nucleus. Nuclear localization of endogenous Rap1-GTP was also detected upon physiologic activation. A potential consequence of nuclear localization of Rap1-GTP is the regulation of gene expression. We used a high throughput proteomic approach to identify gene products potentially modulated by Rap1-GTP. Out of 1000 proteins examined, 64 proteins were upregulated and 66 proteins were downregulated. The differentially expressed gene products belong to cytoskeletal regulator proteins, signaling molecules, transcription factors, viability regulators, and protein transporters. This analysis provides the first fingerprint of gene product expression regulated by Rap1 and may contribute to our understanding of malignant transformation mechanisms regulated by this small GTPase.
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Affiliation(s)
- Esther M Lafuente
- Transplantation Biology Research Center, Massachusetts General Hospital, Boston, MA 02129, USA
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27
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Abstract
The Ras superfamily consists of over 50 low-molecular-weight proteins that cycle between an inactive guanosine diphosphate-bound state and an active guanosine triphosphate (GTP)-bound state. They are involved in a variety of signal transduction pathways that regulate cell growth, intracellular trafficking, cell migration, and apoptosis. Several methods have been devised to measure the activation state of Ras proteins, defined as the percent of Ras molecules in the active GTP-bound state. We have previously developed a quantitative biochemical method that can be applied to animal and human tissues and have used it to measure the activation state of Ras, Rap1, Rheb, and Rho proteins in cultured cells and in animal and human tumors. Ras, Rac, and Rho all play roles in regulating the functions of T and B lymphocytes and dendritic cells, and these proteins are clearly important in maintaining normal immune system function.
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Affiliation(s)
- Juergen S Scheele
- Co-ordinating Center for Clinical Trials, Martin Luther University, Halle, Germany
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Martín-Encabo S, Santos E, Guerrero C. C3G mediated suppression of malignant transformation involves activation of PP2A phosphatases at the subcortical actin cytoskeleton. Exp Cell Res 2007; 313:3881-91. [PMID: 17825818 DOI: 10.1016/j.yexcr.2007.07.036] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2007] [Revised: 07/09/2007] [Accepted: 07/27/2007] [Indexed: 11/26/2022]
Abstract
In previous work, we demonstrated that C3G suppresses Ras oncogenic transformation by a mechanism involving inhibition of ERK phosphorylation. Here we present evidences indicating that this suppression mechanism is mediated, at least in part, by serine/threonine phosphatases of the PP2A family. Thus: (i) ectopic expression of C3G or C3GDeltaCat (mutant lacking the GEF activity) increases specific ERK-associated PP2A phosphatase activities; (ii) C3G and PP2A interact, as demonstrated by immunofluorescence and co-immunoprecipitation experiments; (iii) association between PP2A and MEK or ERK increases in C3G overexpressing cells; (iv) phosphorylated-inactive PP2A level decreases in C3G expressing clones and, most importantly, (v) okadaic acid reverts the inhibitory effect of C3G on ERK phosphorylation. Moreover, C3G interacts with Ksr-1, a scaffold protein of the Ras-ERK pathway that also associates with PP2A. The fraction of C3G involved in transformation suppression is restricted to the subcortical actin cytoskeleton where it interacts with actin. Furthermore, the association between C3G and PP2A remains stable even after cytoskeleton disruption with cytochalasin D, suggesting that the three proteins form a complex at this subcellular compartment. Finally, C3G- and C3GDeltaCat-mediated inhibition of ERK phosphorylation is reverted by incubation with cytochalasin D. We hypothesize that C3G triggers PP2A activation and binding to MEK and ERK at the subcortical actin cytoskeleton, thus favouring ERK dephosphorylation.
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Affiliation(s)
- Susana Martín-Encabo
- Centro de Investigación del Cáncer, IBMCC, Universidad de Salamanca-CSIC, 37007-Salamanca, Spain
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Arai A, Aoki M, Weihua Y, Jin A, Miura O. CrkL plays a role in SDF-1-induced activation of the Raf-1/MEK/Erk pathway through Ras and Rac to mediate chemotactic signaling in hematopoietic cells. Cell Signal 2006; 18:2162-71. [PMID: 16781119 DOI: 10.1016/j.cellsig.2006.05.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2006] [Revised: 04/27/2006] [Accepted: 05/04/2006] [Indexed: 12/22/2022]
Abstract
Intracellular signaling mechanisms regulating SDF-1-induced chemotaxis of hematopoietic cells have remained elusive. Here we demonstrate that overexpression of the adaptor molecule CrkL enhances SDF-1-induced chemotaxis of hematopoietic BaF3 and 32Dcl3 cells. Overexpression of CrkL also enhanced SDF-1-induced activation of the Raf-1/MEK/Erk signaling pathway as well as that of the small GTPases Ras, Rap1, and Rac, while a dominant negative mutant of Ras or Rac suppressed CrkL-enhanced Erk activation. SDF-1 stimulation induced tyrosine phosphorylation of CrkL, which was inhibited by the Src family kinase inhibitor PP1 or by dominant negative mutants of Lyn, thus indicating that Lyn mediated SDF-1-induced phosphorylation of CrkL. However, inhibition of the Lyn kinase activity failed to affect SDF-1-induced activation of the small GTPases and Erk. On the other hand, SDF-1-induced activation of the Erk signaling pathway as well as chemotaxis was inhibited by overexpression of a CrkL mutant lacking the N-terminal SH3 domain, which mediates interaction with various signaling molecules including guanine nucleotide exchange factors for the Ras and Rho family GTPases. SDF-1-induced chemotaxis was also inhibited by the dominant negative Ras or Rac mutant as well as by the MEK inhibitor PD98059. These results indicate that CrkL mediates SDF-1-induced activation of the Raf-1/MEK/Erk signaling pathway through Ras as well as Rac in hematopoietic cells and, thereby, plays important roles in the induction of chemotactic response.
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Affiliation(s)
- Ayako Arai
- Department of Hematology, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
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Jin A, Kurosu T, Tsuji K, Mizuchi D, Arai A, Fujita H, Hattori M, Minato N, Miura O. BCR/ABL and IL-3 activate Rap1 to stimulate the B-Raf/MEK/Erk and Akt signaling pathways and to regulate proliferation, apoptosis, and adhesion. Oncogene 2006; 25:4332-40. [PMID: 16518411 DOI: 10.1038/sj.onc.1209459] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The Ras family small GTPase Rap1 is activated by hematopoietic cytokines, such as interleukin (IL)-3, to induce beta1 integrin-mediated cell adhesion or by the BCR/ABL fusion tyrosine kinase to stimulate the MEK/Erk signaling pathway. Here, we demonstrate that the abrogation of Rap1 activation by SPA-1, a Rap1-specific GAP, inhibits activation of B-Raf, MEK, Erk, and Akt in a murine hematopoietic cell line, Ton.B210, stimulated with IL-3 or inducibly expressing BCR/ABL. Furthermore, Rap1 inactivation had an inhibitory effects on proliferation and survival of Ton.B210 cells, which were more remarkable when cells were stimulated by BCR/ABL than by IL-3. Induction of BCR/ABL expression increased adhesion of Ton.B210 cells to fibronectin in a manner at least partly dependent on its kinase activity, and Rap1 inhibition by SPA-1 partially inhibited BCR/ABL-induced adhesion of cells. Thus, IL-3- or BCR/ABL-induced activation of Rap1 may play important roles in regulation of cell proliferation and survival through activation of the B-Raf/MEK/Erk and Akt signaling pathways and in induction of integrin-mediated cell adhesion. Furthermore, as compared with IL-3, BCR/ABL is more dependent on Rap1-mediated signaling to induce cell proliferation and survival and, thus, Rap1 may represent an attractive target for novel therapies for leukemias caused by BCR/ABL.
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Affiliation(s)
- A Jin
- Department of Hematology, Tokyo Medical and Dental University, Japan
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31
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Gutiérrez-Berzal J, Castellano E, Martín-Encabo S, Gutiérrez-Cianca N, Hernández JM, Santos E, Guerrero C. Characterization of p87C3G, a novel, truncated C3G isoform that is overexpressed in chronic myeloid leukemia and interacts with Bcr-Abl. Exp Cell Res 2006; 312:938-48. [PMID: 16443220 DOI: 10.1016/j.yexcr.2005.12.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2005] [Revised: 12/05/2005] [Accepted: 12/06/2005] [Indexed: 11/17/2022]
Abstract
A novel C3G isoform, designated p87C3G, lacking the most amino terminal region of the cognate protein has been found to be overexpressed in two CML cell lines, K562 and Boff 210, both expressing Bcr-Abl p210. p87C3G expression is also highly augmented in patients diagnosed with chronic myeloid leukemia (CML) Ph+, in comparison with healthy individuals, and returns to basal levels after treatment with STI571. p87C3G co-immunoprecipitates with both CrkL and Bcr-Abl in CML cell lines and co-immunoprecipitation between p87C3G and Bcr-Abl was also detected in primary cells from CML patients. These interactions have been confirmed by in vitro pull down experiments. The interaction between p87C3G and Bcr-Abl involves the SH3-binding domain of p87C3G and the SH3 domain of Abl and depends mostly on the first polyproline region of p87C3G. Furthermore, we also demonstrated that p87C3G is phosphorylated in vitro by a Bcr-Abl-dependent mechanism. These results indicate that p87C3G overexpression is linked to CML phenotype and that p87C3G may exert productive functional interactions with Bcr-Abl signaling components suggesting the implication of this C3G isoform in the pathogenesis of chronic myeloid leukemia.
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MESH Headings
- Adaptor Proteins, Signal Transducing/metabolism
- Cell Line, Tumor
- Cloning, Molecular
- Fusion Proteins, bcr-abl
- Gene Expression Regulation, Leukemic
- Genes, abl/genetics
- Guanine Nucleotide-Releasing Factor 2/genetics
- Guanine Nucleotide-Releasing Factor 2/metabolism
- Humans
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/metabolism
- Leukocytes, Mononuclear/cytology
- Leukocytes, Mononuclear/metabolism
- Nuclear Proteins/metabolism
- Phosphorylation
- Protein Isoforms/genetics
- Protein Isoforms/metabolism
- Protein Structure, Tertiary
- Protein-Tyrosine Kinases/metabolism
- src Homology Domains
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Affiliation(s)
- Javier Gutiérrez-Berzal
- Centro de Investigación del Cáncer, IBMCC, Universidad de Salamanca-CSIC, Campus Miguel de Unamuno, 37007 Salamanca, Spain
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32
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Abstract
The small GTPase Rap1 has been involved in different cellular processes. Rap1 is known to increase cell adhesion by means of integrin activation, to induce cell spreading, and to regulate adherent junctions at cell-cell contacts. How Rap1 mediates these cell responses is poorly known, but currently developing evidence points to the involvement of different effector pathways. Recently, we described RIAM, a Rap1 interacting adaptor protein that regulates integrin activation and hence cell adhesion. RIAM is required for Rap1-induced adhesion and seems to control Rap1 localization at the plasma membrane, where Rap1 regulates integrin activation. In this chapter, we focus in the role of RIAM in regulating Rap1-mediated cell adhesion. We describe the method for studying the Rap1-RIAM interaction using in vitro and in vivo approaches such as yeast two hybrids, pull-down assays. and coimmunoprecipitation. The role of Rap1 and RIAM in integrin-mediated adhesion is studied by cell adhesion assays to immobilized integrin substrates and by changes in integrin activation as determined by activation epitope exposure. Finally, we describe an approach to determine the role of RIAM in regulating intracellular localization of active Rap1.
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Affiliation(s)
- Esther Lafuente
- Transplantation Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
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Cho YJ, Hemmeryckx B, Groffen J, Heisterkamp N. Interaction of Bcr/Abl with C3G, an exchange factor for the small GTPase Rap1, through the adapter protein Crkl. Biochem Biophys Res Commun 2005; 333:1276-83. [PMID: 15982636 DOI: 10.1016/j.bbrc.2005.06.030] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2005] [Accepted: 06/08/2005] [Indexed: 11/22/2022]
Abstract
The Bcr/Abl oncoprotein is directly responsible for the development of chronic myelogenous leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia in humans. The adapter protein Crkl is one of the most prominently tyrosine-phosphorylated substrates of Bcr/Abl in cells and tissues isolated from such patients. The guanine nucleotide exchange factor for the small GTPase Rap1, C3G, binds constitutively to Crkl. Here, we report that Crkl mediates the formation of protein complexes that include C3G and Bcr/Abl. These complexes contain highly elevated levels of tyrosine-phosphorylated C3G and P130Cas, a scaffolding protein. Moreover, the presence of Rap1 further promoted tyrosine phosphorylation of C3G and Cas. Co-expression of Crkl and C3G with Bcr/Abl generated increased levels of activated Rap1. In addition, lysates from leukemic cells of P190 BCR/ABL transgenic mice and of the myelogenous leukemia cell line K562 contained tyrosine-phosphorylated C3G and activated Rap1. These data suggest a role for C3G-mediated Rap1 activation in Bcr/Abl-induced leukemia development.
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Affiliation(s)
- Young Jin Cho
- Section of Molecular Carcinogenesis, Division of Hematology/Oncology, Childrens Hospital Los Angeles Saban Research Institute, 4650 Sunset Boulevard, Los Angeles, CA 90027, USA
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Li L, Greenwald RJ, Lafuente EM, Tzachanis D, Berezovskaya A, Freeman GJ, Sharpe AH, Boussiotis VA. Rap1-GTP Is a Negative Regulator of Th Cell Function and Promotes the Generation of CD4+CD103+ Regulatory T Cells In Vivo. THE JOURNAL OF IMMUNOLOGY 2005; 175:3133-9. [PMID: 16116203 DOI: 10.4049/jimmunol.175.5.3133] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The small GTPase Rap1 is transiently activated during TCR ligation and regulates integrin-mediated adhesion. To understand the in vivo functions of Rap1 in regulating T cell immune responses, we generated transgenic (Tg) mice, which express the active GTP-bound mutant Rap1E63 in their T lymphocytes. Although Rap1E63-Tg T cells exhibited increased LFA-1-mediated adhesion, ERK1/2 activation and proliferation of Rap1E63-Tg CD4+ T cells were defective. Rap1E63-Tg T cells primed in vivo and restimulated with specific Ag in vitro, exhibited reduced proliferation and produced reduced levels of IL-2. Rap1E63-Tg mice had severely deficient T cell-dependent B cell responses, as determined by impaired Ig class switching. Rap1E63-Tg mice had an increased fraction of CD4+CD103+ regulatory T cells (Treg), which exhibited enhanced suppressive efficiency as compared with CD4+CD103+ Treg from normal littermate control mice. Depletion of CD103+ Treg significantly restored the impaired responses of Rap1E63-Tg CD4+ T cells. Thus Rap1-GTP is a negative regulator of Th cell responses and one mechanism responsible for this effect involves the increase of CD103+ Treg cell fraction. Our results show that Rap1-GTP promotes the generation of CD103+ Treg and may have significant implications in the development of strategies for in vitro generation of Treg for the purpose of novel immunotherapeutic approaches geared toward tolerance induction.
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Affiliation(s)
- Lequn Li
- Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115, USA
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Stork PJS, Dillon TJ. Multiple roles of Rap1 in hematopoietic cells: complementary versus antagonistic functions. Blood 2005; 106:2952-61. [PMID: 16076873 PMCID: PMC1895320 DOI: 10.1182/blood-2005-03-1062] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Small G proteins serve as critical control points in signal transduction, integrating a wide range of stimuli to dictate discrete cellular outcomes. The outcomes of small G-protein signaling can both potentiate and antagonize one another. Studies in hematopoietic cells have uncovered multiple functions for the small G protein, Rap1 (Ras-proximate-1). Because Rap1 can regulate cell proliferation, differentiation, and adhesion through distinct mechanisms, it serves as a paradigm for the need for tight cellular control of small G-protein function. Rap1 has received recent attention for its role in enhancing integrin-dependent signals. This action of Rap1 augments a variety of processes that characterize hematopoietic-cell function, including aggregation, migration, extravasation, and homing to target tissues. Rap1 may also regulate cellular differentiation and proliferation via pathways that are distinct from those mediating adhesion, and involve regulation of the mitogen-activated protein (MAP) kinase or ERK (extracellular signal-regulated kinase) cascade. These actions of Rap1 occur in selected cell types to enhance or diminish ERK signaling, depending on the expression pattern of the MAP kinase kinase kinases of the Raf family: Raf-1 and B-Raf. This review will examine the functions of Rap1 in hematopoietic cells, and focus on 3 cellular scenarios where the multiple actions of Rap1 function have been proposed. Recent studies implicating Rap1 in the maturation of megakaryocytes, the pathogenesis of chronic myelogenous leukemia (CML), and activation of peripheral T cells will receive particular attention.
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Affiliation(s)
- Philip J S Stork
- Vollum Institute, L474, Oregon Health & Sciences University, 3181 SW Sam Jackson Park Rd, Portland, OR 97239, USA.
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Arai A, Jin A, Yan W, Mizuchi D, Yamamoto K, Nanki T, Miura O. SDF-1 synergistically enhances IL-3-induced activation of the Raf-1/MEK/Erk signaling pathway through activation of Rac and its effector Pak kinases to promote hematopoiesis and chemotaxis. Cell Signal 2005; 17:497-506. [PMID: 15601627 DOI: 10.1016/j.cellsig.2004.09.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2004] [Accepted: 09/10/2004] [Indexed: 11/23/2022]
Abstract
Stromal cell-derived factor 1 (SDF-1) cooperates with cytokines to promote hematopoiesis. Here we demonstrate that SDF-1 activates Erk synergistically with interleukin-3 (IL-3) in hematopoietic cells. Small GTPases Ras and Rac were prominently activated by IL-3 and SDF-1, respectively. In accordance with this, Raf-1 was significantly activated by IL-3 but not by SDF-1. SDF-1 strongly induced phosphorylation of Raf-1 on S338, the target site for the Rac effector Paks, and enhanced the IL-3-induced activation of Raf-1 and MEK. Furthermore, the synergistic activation of Erk was inhibited by expression of a dominant-negative mutant of Pak1 or that of Rac and was enhanced by an activated mutant of Pak1. SDF-1 and IL-3 also showed synergistic effects on expansion of hematopoietic cells and on induction of chemotaxis, which were both inhibited by the MEK inhibitor PD98059. These results suggest that SDF-1 synergistically enhances IL-3-induced Erk activation by up-regulating Raf-1 activity through the Rac effector Pak kinases to promote hematopoiesis.
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Affiliation(s)
- Ayako Arai
- Department of Hematology, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan.
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Raychaudhuri R, Batjer HH, Awad IA. Intracranial cavernous angioma: a practical review of clinical and biological aspects. ACTA ACUST UNITED AC 2005; 63:319-28; discussion 328. [PMID: 15808709 DOI: 10.1016/j.surneu.2004.05.032] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2003] [Accepted: 05/17/2004] [Indexed: 10/25/2022]
Abstract
BACKGROUND Cavernomas are an uncommon lesion seen in neurosurgical practice that can occasionally rupture. Recent developments in neurosurgical technique and microbiology have brought greater insight into the treatment and molecular pathogenesis of cavernoma. In this review, a historical overview of cavernous angioma, a current paradigm for treatment, promising new molecular biological developments, and suggestions for future directions in neurosurgical research are presented, with emphasis on practical clinical applications. METHODS A survey of the literature on cavernous angioma and consultation with the Department of Neurosurgery at Northwestern Memorial Hospital was conducted by the authors to gain greater insight regarding this lesion. Papers and consultation revealed the importance of careful evaluation of this lesion, new techniques such as functional magnetic resonance imaging and frameless stereotaxy that simplify clinical management of cavernomas, and potential mechanisms by which to tackle this lesion in the future. New basic knowledge on disease biology is summarized with practical applications in the clinical arena. RESULTS There appear to be a number of controversies regarding management of this lesion. These include risk factors faced by the patient, controversy over the importance of resection, and modality through which the treatment should occur. An algorithm is presented to aid the neurosurgeon in management of these lesions. CONCLUSIONS Exciting developments in neurosurgery and molecular biology will continue to have a major impact on clinical treatment of this disease. Unresolved issues regarding the importance of certain risk factors, the role for radiotherapy in treatments, and the underlying molecular abnormalities must be tackled to gain greater clarity in treatment of this lesion.
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Affiliation(s)
- Ratul Raychaudhuri
- Department of Neurological Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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Mizuchi D, Kurosu T, Kida A, Jin ZH, Jin A, Arai A, Miura O. BCR/ABL activates Rap1 and B-Raf to stimulate the MEK/Erk signaling pathway in hematopoietic cells. Biochem Biophys Res Commun 2005; 326:645-51. [PMID: 15596148 DOI: 10.1016/j.bbrc.2004.11.086] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2004] [Indexed: 11/17/2022]
Abstract
The BCR/ABL fusion tyrosine kinase activates various intracellular signaling pathways, thus causing chronic myeloid leukemia (CML). Here we demonstrate that the inducible expression of BCR/ABL in a murine hematopoietic cell line, TonB210, leads to the activation of the Ras family small GTPase Rap1, which is inhibited by the ABL kinase inhibitor imatinib. The Rap1 activity in a CML cell line, K562, was also inhibited by imatinib. Inhibition of Rap1 activation by a dominant negative mutant of Rap1, Rap1-N17, or SPA-1 inhibited the BCR/ABL-induced activation of Elk-1. BCR/ABL also activated in a kinase activity-dependent manner the B-Raf kinase, which is an effector molecule of Rap1 and a potent activator of the MEK/Erk/Elk-1 signaling pathway. Together, these data suggest that, in addition to the well-established Ras/Raf-1 pathway, BCR/ABL activates the alternative signaling pathway involving Rap1 and B-Raf to activate Erk, which may play important roles in leukemogenesis.
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Affiliation(s)
- Daisuke Mizuchi
- Department of Hematology, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
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Sakamoto H, Zhang XQ, Suenobu S, Ohbo K, Ogawa M, Suda T. Cell adhesion to ephrinb2 is induced by EphB4 independently of its kinase activity. Biochem Biophys Res Commun 2004; 321:681-7. [PMID: 15358160 DOI: 10.1016/j.bbrc.2004.07.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2004] [Indexed: 11/30/2022]
Abstract
Cell to cell interaction in bone marrow is crucial for differentiation of hematopoietic cells. We have shown that EphB4 receptor is expressed in erythroid progenitor and its activation accelerates erythroid differentiation. To elucidate the role of EphB4 activation in erythropoiesis, we analyzed effects of EphB4 on cell adhesive pathways. Cell adhesion with the extension of filopodial pseudopod was observed by EphB4 activation. EphB4 activation also enhanced an effect of fibronectin-mediated adhesive pathway along with formation of the c-Cbl/CrkL complex. The tyrosine kinase activity of EphB4 was dispensable for those phenomena. These results suggest that activation of EphB4 participates in adhesive but not repulsive signals independently of its tyrosine kinase activity in hematopoietic cells.
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Affiliation(s)
- Hiroshi Sakamoto
- The Sakaguchi Laboratory of Developmental Biology, School of Medicine, Keio University, Tokyo 160-8582, Japan
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Guerrero C, Martín-Encabo S, Fernández-Medarde A, Santos E. C3G-mediated suppression of oncogene-induced focus formation in fibroblasts involves inhibition of ERK activation, cyclin A expression and alterations of anchorage-independent growth. Oncogene 2004; 23:4885-93. [PMID: 15077165 DOI: 10.1038/sj.onc.1207622] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We showed previously that exogenous overexpression of C3G, a guanine nucleotide releasing factor (GEF) for Rap1 and R-Ras proteins, blocks the focus-forming activity of cotransfected, activated, sis, ras and v-raf oncogenes in NIH 3T3 cells. In this report, we show that C3G also interferes with dbl and R-Ras focus-forming activity and demonstrate that the transformation suppressor ability of C3G maps to its Crk-binding region (SH3-b domain). Using full-length C3G and C3GDeltaCat mutant, lacking catalytic domain, we showed here that overexpression of cotransfected C3G or C3GDeltaCat inhibited oncogenic Hraslys12-mediated phosphorylation of ERK, without altering Ras and Raf-1 kinase activation. We also showed that, overexpressed C3G and C3GdeltaCat inhibited the viability of oncogenic Ras-induced colonies in soft agar, indicating that C3G interferes with the anchorage-independent growth of Ras-transformed cells in a Rap1-independent manner. Consistent with both observations, overexpression of exogenous C3G and C3GDeltaCat also caused downregulation of Ras-induced cyclin A expression. Altogether, our results indicate that C3G interferes with at least two separate aspects of oncogenic transformation - cell cycle progression and loss of contact inhibition - and that these inhibitory effects probably account for its transformation suppressor activity.
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Affiliation(s)
- Carmen Guerrero
- Centro de Investigación del Cáncer, IBMCC, Universidad de Salamanca-CSIC, 37007-Salamanca, Spain
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McLeod SJ, Shum AJ, Lee RL, Takei F, Gold MR. The Rap GTPases regulate integrin-mediated adhesion, cell spreading, actin polymerization, and Pyk2 tyrosine phosphorylation in B lymphocytes. J Biol Chem 2003; 279:12009-19. [PMID: 14701796 DOI: 10.1074/jbc.m313098200] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Integrin-mediated adhesion plays an important role in B cell development and activation. Signaling initiated by antigens, chemokines, or phorbol esters can rapidly convert integrins to an activated adhesion-competent state. The binding of integrins to their ligands can then induce actin-dependent cell spreading, which can facilitate cell-cell adhesion or cell migration on extracellular matrices. The signaling pathways involved in integrin activation and post-adhesion events in B cells are not completely understood. We have previously shown that anti-Ig antibodies, the chemokine stromal cell-derived factor-1 (SDF-1; CXCL12), and phorbol esters activate the Rap1 and Rap2 GTPases in B cells and that Rap activation is essential for SDF-1-induced B cell migration (McLeod, S. J., Li, A. H. Y., Lee, R. L., Burgess, A. E., and Gold, M. R. (2002) J. Immunol. 169, 1365-1371; Christian, S. L., Lee, R. L., McLeod, S. J., Burgess, A. E., Li, A. H. Y., Dang-Lawson, M., Lin, K. B. L., and Gold, M. R. (2003) J. Biol. Chem. 278, 41756-41767). We show here that preventing Rap activation by expressing Rap-specific GTPase-activating protein II (RapGAPII) significantly decreased lymphocyte function-associated antigen-1- and alpha(4) integrin-dependent binding of murine B cell lines to purified adhesion molecules and to other cells. Conversely, augmenting Rap activation by expressing a constitutively active form of Rap2 enhanced B cell adhesion, showing for the first time that Rap2 can promote integrin activation. We also show that blocking Rap activation inhibited anti-Ig-induced cell spreading and phorbol ester-induced actin polymerization as well as anti-Ig- and SDF-1-induced phosphorylation of Pyk2, a tyrosine kinase involved in morphological changes and chemokine-induced B cell migration. Thus, the Rap GTPases regulate integrin-mediated B cell adhesion as well as processes that control B cell morphology and migration.
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Affiliation(s)
- Sarah J McLeod
- Department of Microbiology and Immunology, University of British Columbia, 6174 University Boulevard, Vancouver, BC V6T 1Z3, Canada
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Kinbara K, Goldfinger LE, Hansen M, Chou FL, Ginsberg MH. Ras GTPases: integrins' friends or foes? Nat Rev Mol Cell Biol 2003; 4:767-76. [PMID: 14570053 DOI: 10.1038/nrm1229] [Citation(s) in RCA: 178] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Integrins are cell-surface receptors that mediate and coordinate cellular responses to the extracellular matrix (ECM). Cellular signalling pathways can regulate cell adhesion by altering the affinity and avidity of integrins for ECM. The Ras family of small G proteins, which includes H-ras, R-ras and Rap, are important elements in cellular signalling pathways that control integrin function.
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Affiliation(s)
- Kayoko Kinbara
- Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037, USA
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Boettner B, Harjes P, Ishimaru S, Heke M, Fan HQ, Qin Y, Van Aelst L, Gaul U. The AF-6 Homolog Canoe Acts as a Rap1 Effector During Dorsal Closure of the Drosophila Embryo. Genetics 2003; 165:159-69. [PMID: 14504224 PMCID: PMC1462758 DOI: 10.1093/genetics/165.1.159] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
Rap1 belongs to the highly conserved Ras subfamily of small GTPases. In Drosophila, Rap1 plays a critical role in many different morphogenetic processes, but the molecular mechanisms executing its function are unknown. Here, we demonstrate that Canoe (Cno), the Drosophila homolog of mammalian junctional protein AF-6, acts as an effector of Rap1 in vivo. Cno binds to the activated form of Rap1 in a yeast two-hybrid assay, the two molecules colocalize to the adherens junction, and they display very similar phenotypes in embryonic dorsal closure (DC), a process that relies on the elongation and migration of epithelial cell sheets. Genetic interaction experiments show that Rap1 and Cno act in the same molecular pathway during DC and that the function of both molecules in DC depends on their ability to interact. We further show that Rap1 acts upstream of Cno, but that Rap1, unlike Cno, is not involved in the stimulation of JNK pathway activity, indicating that Cno has both a Rap1-dependent and a Rap1-independent function in the DC process.
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Affiliation(s)
- Benjamin Boettner
- Laboratory of Developmental Neurogenetics, Rockefeller University, New York, New York 10021, USA
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Ling L, Zhu T, Lobie PE. Src-CrkII-C3G-dependent activation of Rap1 switches growth hormone-stimulated p44/42 MAP kinase and JNK/SAPK activities. J Biol Chem 2003; 278:27301-11. [PMID: 12734187 DOI: 10.1074/jbc.m302516200] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We demonstrate here that growth hormone (GH) stimulates the activation of Rap1 and Rap2 in NIH-3T3 cells. Full activation of Rap1 and Rap2 by GH necessitated the combined activity of both JAK2 and c-Src kinases, although c-Src was predominantly required. GH-stimulated Rap1 and Rap2 activity was also demonstrated to be CrkII-C3G-dependent. GH stimulated the tyrosine phosphorylation of C3G, which again required the combined activity of JAK2 and c-Src. C3G tyrosine residue 504 was required for GH-stimulated Rap activation. Activated Rap1 inhibited GH-stimulated activation of RalA and subsequent GH-stimulated p44/42 MAP kinase activity and Elk-1-mediated transcription. In addition, we demonstrated that C3G-Rap1 mediated CrkII enhancement of GH-stimulated JNK/SAPK activity. We have therefore identified a linear JAK2-independent pathway switching GH-stimulated p44/42 MAP kinase and JNK/SAPK activities.
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Affiliation(s)
- Ling Ling
- Institute of Molecular and Cell Biology, 30 Medical Drive, Singapore 117609
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45
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Ishida D, Kometani K, Yang H, Kakugawa K, Masuda K, Iwai K, Suzuki M, Itohara S, Nakahata T, Hiai H, Kawamoto H, Hattori M, Minato N. Myeloproliferative stem cell disorders by deregulated Rap1 activation in SPA-1-deficient mice. Cancer Cell 2003; 4:55-65. [PMID: 12892713 DOI: 10.1016/s1535-6108(03)00163-6] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
SPA-1 (signal-induced proliferation-associated gene-1) is a principal Rap1 GTPase-activating protein in hematopoietic progenitors. SPA-1-deficient mice developed a spectrum of myeloid disorders that resembled human chronic myelogenous leukemia (CML) in chronic phase, CML in blast crisis, and myelodysplastic syndrome as well as anemia. Preleukemic SPA-1-deficient mice revealed selective expansion of marrow pluripotential hematopoietic progenitors, which showed abnormal Rap1GTP accumulation. Overexpression of an active form of Rap1 promoted the proliferation of normal hematopoietic progenitors, while SPA-1 overexpression markedly suppressed it. Furthermore, restoring SPA-1 gene in a SPA-1-deficient leukemic blast cell line resulted in the dissolution of Rap1GTP accumulation and concomitant loss of the leukemogenicity in vivo. These results unveiled a role of Rap1 in myeloproliferative stem cell disorders and a tumor suppressor function of SPA-1.
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Affiliation(s)
- Daisuke Ishida
- Department of Immunology and Cell Biology, Graduate School of Biostudies, Kyoto University, 606-8501, Kyoto, Japan
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46
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Abstract
In the paper by Ishida et al. in this issue of Cancer Cell, the authors report the results of targeted inactivation of a Rap1-specific GTPase-activating protein (GAP) gene, called SPA-1, in mice. Rap1 hyperactivation was observed in hematopoietic cells, which led over time to features associated with symptoms typical of human myeloid dyslastic and myeloid proliferative diseases. The authors present additional data showing that the level of Rap1 activation is important for regulating myelopoiesis and that, in the right context, can deliver an oncogenic signal.
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Affiliation(s)
- David A Largaespada
- University of Minnesota Cancer Center, 6-160 Jackson Hall, 321 Church Street S.E., Minneapolis, MN 55455, USA.
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47
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Rehmann H, Rueppel A, Bos JL, Wittinghofer A. Communication between the regulatory and the catalytic region of the cAMP-responsive guanine nucleotide exchange factor Epac. J Biol Chem 2003; 278:23508-14. [PMID: 12707263 DOI: 10.1074/jbc.m301680200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Epac1 is a guanine nucleotide exchange factor (GEF) for the small GTPase Rap1 that is directly activated by cAMP. This protein consists of a regulatory region with a cAMP-binding domain and a catalytic region that mediates the GEF activity. Epac is inhibited by an intramolecular interaction between the cAMP-binding domain and the catalytic region in the absence of cAMP. cAMP binding is proposed to induce a conformational change, which allows a LID, an alpha-helix at the C-terminal end of the cAMP-binding site, to cover the cAMP-binding site (Rehmann, H., Prakash, B., Wolf, E., Rueppel, A., de Rooij, J., Bos, J. L., and Wittinghofer, A. (2003) Nat. Struct. Biol. 10, 26-32). Here we show that mutations of conserved residues in the LID region affect cAMP binding only marginally but have a drastic effect on cAMP-induced GEF activity. Surprisingly, some of the mutants have an increased maximal GEF activity compared with wild type. Furthermore, mutation of the conserved VLVLE sequence at the C-terminal end of the LID into five alanine residues makes Epac constitutively active. From these results we conclude that the LID region plays a pivotal role in the communication between the regulatory and catalytic part of Epac.
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Affiliation(s)
- Holger Rehmann
- Department of Physiological Chemistry and Centre of Biomedical Genetics, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
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48
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de Bruyn KMT, Zwartkruis FJT, de Rooij J, Akkerman JWN, Bos JL. The small GTPase Rap1 is activated by turbulence and is involved in integrin [alpha]IIb[beta]3-mediated cell adhesion in human megakaryocytes. J Biol Chem 2003; 278:22412-7. [PMID: 12690117 DOI: 10.1074/jbc.m212036200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The small GTPase Rap1, which is activated by a large variety of stimuli, functions in the control of integrin-mediated cell adhesion. Here we show that in human megakaryocytes and several other commonly used hematopoietic cell lines such as K562, Jurkat, and THP-1, stress induced by gentle tumbling of the samples resulted in rapid and strong activation of Rap1. This turbulence-induced activation could not be blocked by inhibitors previously shown to affect Rap1 activation in human platelets, such as the intracellular calcium chelator BAPTA-AM (1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid) and various protein kinase C inhibitors. Also inhibition of actin cytoskeleton dynamics did not influence this activation of Rap1, suggesting that this activation is mediated by cell surface receptors. Human platelets, however, were refractory to turbulence-induced activation of Rap1. To determine the consequences of Rap1 activation we measured adhesion of megakaryocytes to fibrinogen, which is mediated by the integrin alphaIIbbeta3, in the presence of inhibitors of Rap1 signaling. Introduction of both Rap1GAP and RalGDS-RBD in the megakaryoblastic cell line DAMI strongly reduced basal adhesion to immobilized fibrinogen. This inhibition was partially rescued by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate but not by alpha-thrombin. From these results we conclude that in megakaryocytes turbulence induces Rap1 activation that controls alphaIIbbeta3-mediated cell adhesion.
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Affiliation(s)
- Kim M T de Bruyn
- Department of Physiological Chemistry, University Medical Center, Utrecht, The Netherlands
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49
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Abstract
Previously, we and others have shown that RhoA and ROCK signaling are required for negatively regulating integrin-mediated adhesion and for tail retraction of migrating leukocytes. This study continues our investigation into the molecular mechanisms underlying RhoA/ROCK-regulated integrin adhesion. We show that inhibition of ROCK up-regulates integrin-mediated adhesion, which is accompanied by both increased phosphotyrosine signaling through Pyk-2 and paxillin and inappropriate membrane protrusions. We provide evidence that inhibition of ROCK induces integrin adhesion by promoting remodeling of the actin cytoskeleton. Furthermore, we find that ROCK regulates membrane activity through a pathway involving cofilin. Inhibition of RhoA signaling allows the formation of multiple competing lamellipodia that disrupt productive migration of monocytes. Together, our results show that RhoA/ROCK signaling promotes migration by restricting integrin activity and membrane protrusions to the leading edge.
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Affiliation(s)
- Rebecca A Worthylake
- Department of Cell and Developmental Biology, Lineberger Comprehensive Cancer Center and Comprehensive Center for Inflammatory Disorders, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
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50
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Abstract
Guanine nucleotide binding proteins rapidly cycle between a guanosine diphosphate (GDP)-bound and guanosine triphosphate (GTP)-bound state, and they operate as binary switches that control cell activation in response to environmental cues. GTPases adopt different conformations when binding GTP vs. GDP. The GTP-bound state is generally considered to be the active conformation that allows GTPases to interact with downstream effectors and thereby initiate downstream signaling pathways, which regulate many important biological processes. Many members of the Ras family of GTPases, notably Ras and Rap1A, and the Rho family GTPases, Cdc42Hs, Rac1, Rac2 and RhoA, are important components of signal transduction pathways used by antigen receptors, costimulatory, cytokine and chemokine receptors to regulate the immune response. This review discusses current knowledge and ideas about the regulation and function of these GTPases in lymphocytes.
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Affiliation(s)
- Doreen Ann Cantrell
- Division of Cell Biology and Immunology, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dundee, UK.
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