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Bedi A, Choi K, Keane C, Bolger-Munro M, Ambrose AR, Gold MR. WAVE2 Regulates Actin-Dependent Processes Induced by the B Cell Antigen Receptor and Integrins. Cells 2023; 12:2704. [PMID: 38067132 PMCID: PMC10705906 DOI: 10.3390/cells12232704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 11/22/2023] [Accepted: 11/22/2023] [Indexed: 12/18/2023] Open
Abstract
B cell antigen receptor (BCR) signaling induces actin cytoskeleton remodeling by stimulating actin severing, actin polymerization, and the nucleation of branched actin networks via the Arp2/3 complex. This enables B cells to spread on antigen-bearing surfaces in order to increase antigen encounters and to form an immune synapse (IS) when interacting with antigen-presenting cells (APCs). Although the WASp, N-WASp, and WAVE nucleation-promoting factors activate the Arp2/3 complex, the role of WAVE2 in B cells has not been directly assessed. We now show that both WAVE2 and the Arp2/3 complex localize to the peripheral ring of branched F-actin when B cells spread on immobilized anti-Ig antibodies. The siRNA-mediated depletion of WAVE2 reduced and delayed B cell spreading on immobilized anti-Ig, and this was associated with a thinner peripheral F-actin ring and reduced actin retrograde flow compared to control cells. Depleting WAVE2 also impaired integrin-mediated B cell spreading on fibronectin and the LFA-1-induced formation of actomyosin arcs. Actin retrograde flow amplifies BCR signaling at the IS, and we found that depleting WAVE2 reduced microcluster-based BCR signaling and signal amplification at the IS, as well as B cell activation in response to antigen-bearing cells. Hence, WAVE2 contributes to multiple actin-dependent processes in B lymphocytes.
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Affiliation(s)
- Abhishek Bedi
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T1Z3, Canada
| | - Kate Choi
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T1Z3, Canada
| | - Connor Keane
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T1Z3, Canada
| | - Madison Bolger-Munro
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T1Z3, Canada
| | - Ashley R Ambrose
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T1Z3, Canada
| | - Michael R Gold
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T1Z3, Canada
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2
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del Rio ML, Perez-Simon JA, Rodriguez-Barbosa JI. Differential Engraftment of Parental A20 PD-L1 WT and PD-L1 KO Leukemia Cells in Semiallogeneic Recipients in the Context of PD-L1/PD-1 Interaction and NK Cell-Mediated Hybrid Resistance. Front Immunol 2022; 13:887348. [PMID: 35795681 PMCID: PMC9251058 DOI: 10.3389/fimmu.2022.887348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 05/19/2022] [Indexed: 11/29/2022] Open
Abstract
The contribution of natural killer (NK) cells to tumor rejection in the context of programmed death-ligand 1/programmed death 1 (PD-L1/PD-1) blockade is a matter of intense debate. To elucidate the role of PD-L1 expression on tumor cells and the functional consequences of engaging PD-1 receptor on cytotoxic cells, PD-L1 expression was genetically inactivated and WT or PD-L1-deficient parental tumor cells were adoptively transferred intravenously into F1 recipients. The engraftment of PD-L1-deficient A20 tumor cells in the spleen and liver of F1 recipients was impaired compared with A20 PD-L1 WT tumor counterparts. To elucidate the mechanism responsible for this differential tumor engraftment and determine the relevance of the role of the PD-L1/PD-1 pathway in the interplay of tumor cells/NK cells, a short-term competitive tumor implantation assay in the peritoneal cavity of semiallogeneic F1 recipients was designed. The results presented herein showed that NK cells killed target tumor cells with similar efficiency regardless of PD-L1 expression, whereas PD-L1 expression on A20 tumor cells conferred significant tumor protection against rejection by CD8 T cells confirming the role of the co-inhibitory receptor PD-1 in the modulation of their cytotoxic activity. In summary, PD-L1 expression on A20 leukemia tumor cells modulates CD8 T-cell-mediated responses to tumor-specific antigens but does not contribute to inhibit NK cell-mediated hybrid resistance, which correlates with the inability to detect PD-1 expression on NK cells neither under steady-state conditions nor under inflammatory conditions.
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Affiliation(s)
- Maria-Luisa del Rio
- Transplantation Immunobiology and Immunotherapy Section, Institute of Molecular Biology, University of Leon, Leon, Spain
- CIBERONC Consortium, Accion Estrategica en Salud, Spain
| | - Jose-Antonio Perez-Simon
- CIBERONC Consortium, Accion Estrategica en Salud, Spain
- Department of Hematology, University Hospital Virgen del Rocio/Institute of Biomedicine [Instituto de Biomedicina de Sevilla (IBIS)/Centro Superior de Investigaciones Científicas (CSIC)/Centro de Investigación Biomédica en Red Cáncer (CIBERONC)], Seville, Spain
| | - Jose-Ignacio Rodriguez-Barbosa
- Transplantation Immunobiology and Immunotherapy Section, Institute of Molecular Biology, University of Leon, Leon, Spain
- CIBERONC Consortium, Accion Estrategica en Salud, Spain
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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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Sia KCS, Zhong L, Mayoh C, Norris MD, Haber M, Marshall GM, Raftery MJ, Lock RB. Targeting TSLP-Induced Tyrosine Kinase Signaling Pathways in CRLF2-Rearranged Ph-like ALL. Mol Cancer Res 2020; 18:1767-1776. [PMID: 32801162 DOI: 10.1158/1541-7786.mcr-19-1098] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 06/30/2020] [Accepted: 08/04/2020] [Indexed: 11/16/2022]
Abstract
Philadelphia (Ph)-like acute lymphoblastic leukemia (ALL) is characterized by aberrant activation of signaling pathways and high risk of relapse. Approximately 50% of Ph-like ALL cases overexpress cytokine receptor-like factor 2 (CRLF2) associated with gene rearrangement. Activated by its ligand thymic stromal lymphopoietin (TSLP), CRLF2 signaling is critical for the development, proliferation, and survival of normal lymphocytes. To examine activation of tyrosine kinases regulated by TSLP/CRLF2, phosphotyrosine (P-Tyr) profiling coupled with stable isotope labeling of amino acids in cell culture (SILAC) was conducted using two CRLF2-rearranged (CRLF2r) Ph-like ALL cell lines stimulated with TSLP. As a result, increased P-Tyr was detected in previously reported TSLP-activated tyrosine kinases and substrates, including JAK1, JAK2, STAT5, and ERK1/2. Interestingly, TSLP also increased P-Tyr of insulin growth factor 1 receptor (IGF1R) and fibroblast growth factor receptor 1 (FGFR1), both of which can be targeted with small-molecule inhibitors. Fixed-ratio combination cytotoxicity assays using the tyrosine kinase inhibitors BMS-754807 and ponatinib that target IGF1R and FGFR1, respectively, revealed strong synergy against both cell line and patient-derived xenograft (PDX) models of CRLF2r Ph-like ALL. Further analyses also indicated off-target effects of ponatinib in the synergy, and novel association of the Ras-associated protein-1 (Rap1) signaling pathway with TSLP signaling in CRLF2r Ph-like ALL. When tested in vivo, the BMS-754807/ponatinib combination exerted minimal efficacy against 2 Ph-like ALL PDXs, associated with low achievable plasma drug concentrations. Although this study identified potential new targets in CRLF2r Ph-like ALL, it also highlights that in vivo validation of synergistic drug interactions is essential. IMPLICATION: Quantitative phosphotyrosine profiling identified potential therapeutic targets for high-risk CRLF2-rearranged Ph-like ALL.
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Affiliation(s)
- Keith C S Sia
- Children's Cancer Institute, School of Women's and Children's Health, UNSW Sydney, Sydney, Australia
| | - Ling Zhong
- Bioanalytical Mass Spectrometry Facility, Mark Wainwright Analytical Centre, UNSW Sydney, Sydney, Australia
| | - Chelsea Mayoh
- Children's Cancer Institute, School of Women's and Children's Health, UNSW Sydney, Sydney, Australia
| | - Murray D Norris
- Children's Cancer Institute, School of Women's and Children's Health, UNSW Sydney, Sydney, Australia.,UNSW Centre for Childhood Cancer Research, UNSW Sydney, Sydney, Australia
| | - Michelle Haber
- Children's Cancer Institute, School of Women's and Children's Health, UNSW Sydney, Sydney, Australia
| | - Glenn M Marshall
- Children's Cancer Institute, School of Women's and Children's Health, UNSW Sydney, Sydney, Australia.,Kids Cancer Centre, Sydney Children's Hospital, Randwick, Australia
| | - Mark J Raftery
- Bioanalytical Mass Spectrometry Facility, Mark Wainwright Analytical Centre, UNSW Sydney, Sydney, Australia
| | - Richard B Lock
- Children's Cancer Institute, School of Women's and Children's Health, UNSW Sydney, Sydney, Australia. .,UNSW Centre for Childhood Cancer Research, UNSW Sydney, Sydney, Australia
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5
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Wang X, Wang C, Xi L, Yu Z. Rap2c as a Novel Biomarker for Predicting Poor Prognosis in Glioma. Onco Targets Ther 2020; 13:3073-3083. [PMID: 32341653 PMCID: PMC7166057 DOI: 10.2147/ott.s247731] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 03/26/2020] [Indexed: 02/02/2023] Open
Abstract
Objective Rap2c is a member of the Ras superfamily that has been implicated in various types of cancers. However, its role in glioma remains elusive. This study aimed to elucidate the role of Rap2c in glioma and its specific molecular mechanism. Methods We determined the expression of Rap2c in glioma tissues by Western blotting and immunohistochemistry (IHC) assays. The proliferation and apoptosis of cells were explored using CCK-8 and flow cytometry assay, whereas the migration and invasion of glioma cells were determined using transwell assay. The potential mechanism of Rap2c in the migration of glioma cell lines was investigated through Western blotting analysis and transwell assay. BALB/c nude mice were used to establish tumor models to test the effect of Rap2c on cancer metastasis in vivo. Results Our data showed that the protein expression of Rap2c was significantly up-regulated in glioma tissues compared with normal brain tissues, and Rap2c overexpression negatively correlated with 5-year overall survival rate. However, there was no correlation between Rap2c expression and clinicopathological parameters of glioma patients. Overexpression of Rap2c promoted the migration and invasion abilities of glioma cells but had no significant effect on the proliferation of glioma cells. Western blotting analysis revealed that Rap2c overexpression increased the phosphorylation level of extracellular signal-related kinase1/2 (ERK1/2), and this effect was abolished with U0126, a selective MEK inhibitor. Furthermore, overexpression of Rap2c induced lung metastasis of glioma cells in xenograft models. Conclusion These findings indicate that high Rap2c expression predicts poor prognosis in glioma. Rap2c-mediated ERK1/2 phosphorylation initiates EMT cascade and promotes migration and invasion of glioma cells. Thus, targeting Rap2c and ERK signaling pathway could be a novel treatment modality for glioma.
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Affiliation(s)
- Xiucun Wang
- Department of Neurosurgery, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215006, People's Republic of China.,Department of Neurosurgery, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221002, People's Republic of China
| | - Cheng Wang
- Department of Neurosurgery, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221002, People's Republic of China
| | - Lin Xi
- Department of Neurosurgery, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221002, People's Republic of China
| | - Zhengquan Yu
- Department of Neurosurgery, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215006, People's Republic of China
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6
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Bastidas Torres AN, Cats D, Mei H, Fanoni D, Gliozzo J, Corti L, Paulli M, Vermeer MH, Willemze R, Berti E, Tensen CP. Whole-genome analysis uncovers recurrent IKZF1 inactivation and aberrant cell adhesion in blastic plasmacytoid dendritic cell neoplasm. Genes Chromosomes Cancer 2019; 59:295-308. [PMID: 31846142 PMCID: PMC7079160 DOI: 10.1002/gcc.22831] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 12/04/2019] [Accepted: 12/12/2019] [Indexed: 01/29/2023] Open
Abstract
Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and highly aggressive hematological malignancy with a poorly understood pathobiology and no effective therapeutic options. Despite a few recurrent genetic defects (eg, single nucleotide changes, indels, large chromosomal aberrations) have been identified in BPDCN, none are disease‐specific, and more importantly, none explain its genesis or clinical behavior. In this study, we performed the first high resolution whole‐genome analysis of BPDCN with a special focus on structural genomic alterations by using whole‐genome sequencing and RNA sequencing. Our study, the first to characterize the landscape of genomic rearrangements and copy number alterations of BPDCN at nucleotide‐level resolution, revealed that IKZF1, a gene encoding a transcription factor required for the differentiation of plasmacytoid dendritic cell precursors, is focally inactivated through recurrent structural alterations in this neoplasm. In concordance with the genomic data, transcriptome analysis revealed that conserved IKZF1 target genes display a loss‐of‐IKZF1 expression pattern. Furthermore, up‐regulation of cellular processes responsible for cell‐cell and cell‐ECM interactions, which is a hallmark of IKZF1 deficiency, was prominent in BPDCN. Our findings suggest that IKZF1 inactivation plays a central role in the pathobiology of the disease, and consequently, therapeutic approaches directed at reestablishing the function of this gene might be beneficial for patients.
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Affiliation(s)
| | - Davy Cats
- Sequencing Analysis Support Core, Leiden University Medical Center, Leiden, The Netherlands
| | - Hailiang Mei
- Sequencing Analysis Support Core, Leiden University Medical Center, Leiden, The Netherlands
| | - Daniele Fanoni
- Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Jessica Gliozzo
- Department of Dermatology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Laura Corti
- Department of Dermatology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Marco Paulli
- Unit of Anatomic Pathology, Department of Molecular Medicine, University of Pavia and Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
| | - Maarten H Vermeer
- Department of Dermatology, Leiden University Medical Center, Leiden, The Netherlands
| | - Rein Willemze
- Department of Dermatology, Leiden University Medical Center, Leiden, The Netherlands
| | - Emilio Berti
- Department of Dermatology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Cornelis P Tensen
- Department of Dermatology, Leiden University Medical Center, Leiden, The Netherlands
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7
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Mele S, Devereux S, Pepper AG, Infante E, Ridley AJ. Calcium-RasGRP2-Rap1 signaling mediates CD38-induced migration of chronic lymphocytic leukemia cells. Blood Adv 2018; 2:1551-1561. [PMID: 29970392 PMCID: PMC6039665 DOI: 10.1182/bloodadvances.2017014506] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 05/24/2018] [Indexed: 01/08/2023] Open
Abstract
CD38 is a transmembrane exoenzyme that is associated with poor prognosis in chronic lymphocytic leukemia (CLL). High CD38 levels in CLL cells are linked to increased cell migration, but the molecular basis is unknown. CD38 produces nicotinic acid adenine dinucleotide phosphate and adenosine 5'-diphosphate-ribose, both of which can act to increase intracellular Ca2+ levels. Here we show that CD38 expression increases basal intracellular Ca2+ levels and stimulates CLL cell migration both with and without chemokine stimulation. We find that CD38 acts via intracellular Ca2+ to increase the activity of the Ras family GTPase Rap1, which is in turn regulated by the Ca2+-sensitive Rap1 guanine-nucleotide exchange factor RasGRP2. Both Rap1 and RasGRP2 are required for CLL cell migration, and RasGRP2 is polarized in primary CLL cells with high CD38 levels. These results indicate that CD38 promotes RasGRP2/Rap1-mediated CLL cell adhesion and migration by increasing intracellular Ca2+ levels.
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Affiliation(s)
- Silvia Mele
- Randall Centre for Cell and Molecular Biophysics, and
- School of Cancer Sciences, King's College London, London, United Kingdom
| | - Stephen Devereux
- School of Cancer Sciences, King's College London, London, United Kingdom
| | - Andrea G Pepper
- School of Cancer Sciences, King's College London, London, United Kingdom
- Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom; and
| | | | - Anne J Ridley
- Randall Centre for Cell and Molecular Biophysics, and
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom
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8
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Wang JC, Bolger-Munro M, Gold MR. Visualizing the Actin and Microtubule Cytoskeletons at the B-cell Immune Synapse Using Stimulated Emission Depletion (STED) Microscopy. J Vis Exp 2018. [PMID: 29683438 DOI: 10.3791/57028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
B cells that bind to membrane-bound antigens (e.g., on the surface of an antigen-presenting cell) form an immune synapse, a specialized cellular structure that optimizes B-cell receptor (BCR) signaling and BCR-mediated antigen acquisition. Both the remodeling of the actin cytoskeleton and the reorientation of the microtubule network towards the antigen contact site are essential for immune synapse formation. Remodeling of the actin cytoskeleton into a dense peripheral ring of F-actin is accompanied by polarization of the microtubule-organizing center towards the immune synapse. Microtubule plus-end binding proteins, as well as cortical plus-end capture proteins mediate physical interactions between the actin and microtubule cytoskeletons, which allow them to be reorganized in a coordinated manner. Elucidating the mechanisms that control this cytoskeletal reorganization, as well as understanding how these cytoskeletal structures shape immune synapse formation and BCR signaling, can provide new insights into B cell activation. This has been aided by the development of super-resolution microscopy approaches that reveal new details of cytoskeletal network organization. We describe here a method for using stimulated emission depletion (STED) microscopy to simultaneously image actin structures, microtubules, and transfected GFP-tagged microtubule plus-end binding proteins in B cells. To model the early events in immune synapse formation, we allow B cells to spread on coverslips coated with anti-immunoglobulin (anti-Ig) antibodies, which initiate BCR signaling and cytoskeleton remodeling. We provide step-by-step protocols for expressing GFP fusion proteins in A20 B-lymphoma cells, for anti-Ig-induced cell spreading, and for subsequent cell fixation, Immunostaining, image acquisition, and image deconvolution steps. The high-resolution images obtained using these procedures allow one to simultaneously visualize actin structures, microtubules, and the microtubule plus-end binding proteins that may link these two cytoskeletal networks.
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Affiliation(s)
- Jia C Wang
- Department of Microbiology and Immunology, University of British Columbia
| | | | - Michael R Gold
- Department of Microbiology and Immunology, University of British Columbia;
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9
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Guerrero-Martínez JA, Reyes JC. High expression of SMARCA4 or SMARCA2 is frequently associated with an opposite prognosis in cancer. Sci Rep 2018; 8:2043. [PMID: 29391527 PMCID: PMC5794756 DOI: 10.1038/s41598-018-20217-3] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 01/16/2018] [Indexed: 12/21/2022] Open
Abstract
The gene encoding the ATPase of the chromatin remodeling SWI/SNF complexes SMARCA4 (BRG1) is often mutated or silenced in tumors, suggesting a role as tumor suppressor. Nonetheless, recent reports show requirement of SMARCA4 for tumor cells growth. Here, we performed a computational meta-analysis using gene expression, prognosis, and clinicopathological data to clarify the role of SMARCA4 and the alternative SWI/SNF ATPase SMARCA2 (BRM) in cancer. We show that while the SMARCA4 gene is mostly overexpressed in tumors, SMARCA2 is almost invariably downexpressed in tumors. High SMARCA4 expression was associated with poor prognosis in many types of tumors, including liver hepatocellular carcinoma (LIHC), and kidney renal clear cell carcinoma (KIRC). In contrast, high SMARCA2 expression was associated with good prognosis. We compared tumors with high versus low expression of SMARCA4 or SMARCA2 in LIHC and KIRC cohorts from The Cancer Genome Atlas. While a high expression of SMARCA4 is associated with aggressive tumors, a high expression of SMARCA2 is associated with benign differentiated tumors, suggesting that SMARCA4 and SMARCA2 play opposite roles in cancer. Our results demonstrate that expression of SMARCA4 and SMARCA2 have a high prognostic value and challenge the broadly accepted general role of SMARCA4 as a tumor suppressor.
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Affiliation(s)
- Jose A Guerrero-Martínez
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla-Universidad Pablo de Olavide (CSIC-USE-UPO). Av. Americo Vespucio 24, 41092, Seville, Spain
| | - Jose C Reyes
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla-Universidad Pablo de Olavide (CSIC-USE-UPO). Av. Americo Vespucio 24, 41092, Seville, Spain.
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10
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Li Y, Li S, Huang L. Knockdown of Rap2B, a Ras Superfamily Protein, Inhibits Proliferation, Migration, and Invasion in Cervical Cancer Cells via Regulating the ERK1/2 Signaling Pathway. Oncol Res 2017; 26:123-130. [PMID: 28390112 PMCID: PMC7844554 DOI: 10.3727/096504017x14912172235777] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Rap2B, belonging to the Ras superfamily, has been implicated in cancer development and functions as a tumor promoter. However, the role of Rap2B in cervical cancer is unknown. In this study, we investigated the expression pattern and biological functions of Rap2B in cervical cancer. The results showed that Rap2B was overexpressed in cervical cancer tissues and cell lines. Knockdown of Rap2B inhibited the proliferation, migration, and invasion of cervical cancer cells. In addition, our tumorigenesis assay showed that Rap2B knockdown suppressed cervical cancer cell growth and metastasis in vivo. We also found that the ERK1/2 signaling pathway is involved in the inhibitory effect of Rap2B knockdown on cervical cancer development. In conclusion, we suggest that Rap2B is an oncogene and may be a promising therapeutic target for cervical cancer.
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Affiliation(s)
- Yinghua Li
- Department of Gynecology and Obstetrics, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, P.R. China
| | - Songyi Li
- Department of Gynecology and Obstetrics, Women's Hospital of Hangzhou City, Hangzhou, P.R. China
| | - Lili Huang
- Department of Gynecology and Obstetrics, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, P.R. China
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11
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Abstract
Ras-associated protein-1 (Rap1), a small GTPase in the Ras-related protein family, is an important regulator of basic cellular functions (e.g., formation and control of cell adhesions and junctions), cellular migration, and polarization. Through its interaction with other proteins, Rap1 plays many roles during cell invasion and metastasis in different cancers. The basic function of Rap1 is straightforward; it acts as a switch during cellular signaling transduction and regulated by its binding to either guanosine triphosphate (GTP) or guanosine diphosphate (GDP). However, its remarkably diverse function is rendered by its interplay with a large number of distinct Rap guanine nucleotide exchange factors and Rap GTPase activating proteins. This review summarizes the mechanisms by which Rap1 signaling can regulate cell invasion and metastasis, focusing on its roles in integrin and cadherin regulation, Rho GTPase control, and matrix metalloproteinase expression.
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Affiliation(s)
- Yi-Lei Zhang
- Key Laboratory of Molecular Biophysics of Ministry of Education, School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Ruo-Chen Wang
- Key Laboratory of Molecular Biophysics of Ministry of Education, School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Ken Cheng
- Sun Yat-sen University, Guangzhou 510275, China
| | - Brian Z Ring
- Key Laboratory of Molecular Biophysics of Ministry of Education, School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Li Su
- Key Laboratory of Molecular Biophysics of Ministry of Education, School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China.,Research Institute of Huazhong University of Science and Technology in Shenzhen, Shenzhen 518063, China
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12
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Gera N, Swanson KD, Jin T. β-Arrestin 1-dependent regulation of Rap2 is required for fMLP-stimulated chemotaxis in neutrophil-like HL-60 cells. J Leukoc Biol 2016; 101:239-251. [PMID: 27493245 DOI: 10.1189/jlb.2a1215-572r] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 06/13/2016] [Accepted: 07/15/2016] [Indexed: 01/14/2023] Open
Abstract
β-Arrestins have emerged as key regulators of cytoskeletal rearrangement that are required for directed cell migration. Whereas it is known that β-arrestins are required for formyl-Met-Leu-Phe receptor (FPR) recycling, less is known about their role in regulating FPR-mediated neutrophil chemotaxis. Here, we show that β-arrestin 1 (ArrB1) coaccumulated with F-actin within the leading edge of neutrophil-like HL-60 cells during chemotaxis, and its knockdown resulted in markedly reduced migration within fMLP gradients. The small GTPase Ras-related protein 2 (Rap2) was found to bind ArrB1 under resting conditions but dissociated upon fMLP stimulation. The FPR-dependent activation of Rap2 required ArrB1 but was independent of Gαi activity. Significantly, depletion of either ArrB1 or Rap2 resulted in reduced chemotaxis and defects in cellular repolarization within fMLP gradients. These data strongly suggest a model in which FPR is able to direct ArrB1 and other bound proteins that are required for lamellipodial extension to the leading edge in migrating neutrophils, thereby orientating and directing cell migration.
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Affiliation(s)
- Nidhi Gera
- Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA; and
| | - Kenneth D Swanson
- Department of Neurology, Division of Neuro-Oncology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Tian Jin
- Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA; and
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13
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Wu J, Sang M, Cao W, Zheng J, Pei D. [Identification analysis of eukaryotic expression plasmid Rap2a and its effect on the migration of lung cancer cells]. ZHONGGUO FEI AI ZA ZHI = CHINESE JOURNAL OF LUNG CANCER 2016; 17:643-8. [PMID: 25248704 PMCID: PMC6000507 DOI: 10.3779/j.issn.1009-3419.2014.09.01] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
背景与目的 小G蛋白家族成员Rap2a可调控内皮素和细胞粘附从而影响细胞运动及细胞与基质间相互作用,但其在肿瘤发生发展中的作用仍属未知。克隆人Ras家族小G蛋白Rap2a的cDNA,构建其真核表达质粒并在肺癌细胞表达,初步探讨Rap2a在肺癌发生发展中的作用。 方法 Western blot检测Rap2a在肺癌细胞中的内源性表达。人骨肉瘤细胞株U2OS提取细胞总RNA,经逆转录聚合酶链式反应逆转录成cDNA,PCR扩增Rap2a基因,酶切后插入pcDNA3.1(+)构建真核表达质粒pcDNA3.1(+)-Rap2a,采用酶切及测序鉴定。重组质粒转染H1299和A549细胞,Western blot检测目的基因表达。Transwell小室迁移实验观察Rap2a对肺癌细胞迁移能力的影响。明胶酶谱实验检测Rap2a对细胞分泌基质金属蛋白酶(matrix metalloproteinase, MMP)2的影响。 结果 与正常细胞相比,肺癌细胞中Rap2a基础表达水平明显增高。双酶切及测序结果显示重组质粒pcDNA3.1(+)-Rap2a成功构建,Werstern blot检测到H1299和A549细胞有相应蛋白表达。迁移实验结果显示转染Rap2a基因后肿瘤细胞迁移能力明显增加。明胶酶谱实验结果显示Rap2a过表达后肺癌细胞分泌MMP2的量随之增加。 结论 人Rap2a真核表达质粒成功构建,Rap2a基因在肺癌细胞株成功表达并能促进肺癌细胞的迁移能力。
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Affiliation(s)
- Jinxia Wu
- Department of Physiology, Xuzhou Medical College, Xuzhou 221002, China;Research Institute of Cancer Prevention and Therapy, Xuzhou Medical College, Xuzhou 221002, China
| | - Miaomiao Sang
- Research Institute of Cancer Prevention and Therapy, Xuzhou Medical College, Xuzhou 221002, China
| | - Wenjia Cao
- Research Institute of Cancer Prevention and Therapy, Xuzhou Medical College, Xuzhou 221002, China
| | - Junnian Zheng
- Research Institute of Cancer Prevention and Therapy, Xuzhou Medical College, Xuzhou 221002, China;Center of Clinical Oncology, Affiliated Hospital of Xuzhou Medical College,
Xuzhou 221002, China
| | - Dongsheng Pei
- Research Institute of Cancer Prevention and Therapy, Xuzhou Medical College, Xuzhou 221002, China
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14
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Wu JX, Zhang DG, Zheng JN, Pei DS. Rap2a is a novel target gene of p53 and regulates cancer cell migration and invasion. Cell Signal 2015; 27:1198-207. [PMID: 25728512 DOI: 10.1016/j.cellsig.2015.02.026] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 02/06/2015] [Accepted: 02/23/2015] [Indexed: 02/08/2023]
Abstract
The p53 transcription factor is a critical regulator of the cell cycle, DNA repair, and apoptosis. Recent evidences suggest that p53 may contribute to the regulation of cell invasion and migration. Rap2a, a member of the small GTPase superfamily, mediates diverse cellular events such as cell adhesion, migration and proliferation through various signaling pathways. In this study, we identify that Rap2a is a novel target of p53 and is induced upon DNA damage in a p53-dependent manner. Upon DNA damage, p53 directly binds to the promoter of Rap2a and activates its transcription. We show that Rap2a is significantly upregulated in many types of tumors. In addition, the ectopic expression of Rap2a enhances the migration and invasive ability of cancer cells and increases activities of matrix metalloproteinase MMP2 and MMP9. In contrast, the inactivation of Rap2a inhibits cell invasion and activities of MMP2 and MMP9. We also show that Rap2a regulates the phosphorylation level of Akt. Collectively, our results show that ectopic expression of Rap2a has a key role in enhancing migration, invasion and metastasis by upregulating p-Akt.
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Affiliation(s)
- Jin-Xia Wu
- Jiangsu Key Laboratory of Biological Cancer Therapy, Xuzhou Medical College, Xuzhou 221002, China
| | - Ding-Guo Zhang
- Jiangsu Key Laboratory of Biological Cancer Therapy, Xuzhou Medical College, Xuzhou 221002, China
| | - Jun-Nian Zheng
- Jiangsu Key Laboratory of Biological Cancer Therapy, Xuzhou Medical College, Xuzhou 221002, China; Center of Clinical Oncology, Affiliated Hospital of Xuzhou Medical College, Xuzhou 221002, China.
| | - Dong-Sheng Pei
- Jiangsu Key Laboratory of Biological Cancer Therapy, Xuzhou Medical College, Xuzhou 221002, China.
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15
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Mele S, Devereux S, Ridley AJ. Rho and Rap guanosine triphosphatase signaling in B cells and chronic lymphocytic leukemia. Leuk Lymphoma 2014; 55:1993-2001. [PMID: 24237579 DOI: 10.3109/10428194.2013.866666] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Chronic lymphocytic leukemia (CLL) cells proliferate predominantly in niches in the lymph nodes, where signaling from the B cell receptor (BCR) and the surrounding microenvironment are critical for disease progression. In addition, leukemic cells traffic constantly from the bloodstream into the lymph nodes, migrate within lymphatic tissues and egress back to the bloodstream. These processes are driven by chemokines and their receptors, and depend on changes in cell migration and integrin-mediated adhesion. Here we describe how Rho and Rap guanosine triphosphatases (GTPases) contribute to both BCR signaling and chemokine receptor signaling, particularly by regulating cytoskeletal dynamics and integrin activity. We propose that new inhibitors of BCR-activated kinases are likely to affect CLL cell trafficking via Rho and Rap GTPases, and that upstream regulators or downstream effectors could be good targets for therapeutic intervention in CLL.
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Affiliation(s)
- Silvia Mele
- Randall Division of Cell and Molecular Biophysics, King's College London , London , UK
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16
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Machtaler S, Choi K, Dang-Lawson M, Falk L, Pournia F, Naus CC, Matsuuchi L. The role of the gap junction protein connexin43 in B lymphocyte motility and migration. FEBS Lett 2014; 588:1249-58. [PMID: 24486015 DOI: 10.1016/j.febslet.2014.01.027] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 01/17/2014] [Accepted: 01/20/2014] [Indexed: 01/13/2023]
Abstract
The gap junction family of proteins is widely expressed in mammalian cells and form intercellular channels between adjacent cells, as well as hemichannels, for transport of molecules between the cell and the surrounding environment. In addition, gap junction proteins have recently been implicated as important for the regulation of cell adhesion and migration in a variety of cell types. The gap junction protein connexin43 (Cx43) regulates B lymphocyte adhesion, BCR- and LFA-1-mediated activation of the GTPase Rap1, and cytoskeletal rearrangements resulting in changes to cell shape and membrane spreading. We demonstrate here that the actin cytoskeleton is important for the distribution of Cx43 in the B cell plasma membrane and for other cell processes involving the cytoskeleton. Using shRNA knockdown of Cx43 in B lymphoma cells we show that Cx43 is also necessary for chemokine-mediated Rap 1 activation, motility, CXCL12-directed migration, and movement across an endothelial cell monolayer. These results demonstrate that in addition to its role in B cell spreading, Cx43 is an important regulator of B-cell motility and migration, processes essential for normal B-cell development and immune responses.
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Affiliation(s)
- Steven Machtaler
- CELL and I(3) Research Groups, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada; Department of Zoology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Kate Choi
- CELL and I(3) Research Groups, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada; Department of Zoology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - May Dang-Lawson
- CELL and I(3) Research Groups, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada; Department of Zoology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Letitia Falk
- CELL and I(3) Research Groups, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada; Department of Zoology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Farnaz Pournia
- CELL and I(3) Research Groups, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada; Department of Zoology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Christian C Naus
- CELL and I(3) Research Groups, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada; Neuroscience Research Group, Life Sciences Institute, Dept of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Linda Matsuuchi
- CELL and I(3) Research Groups, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada; Department of Zoology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada.
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17
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Ras. Mol Oncol 2013. [DOI: 10.1017/cbo9781139046947.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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18
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Tsygankova OM, Wang H, Meinkoth JL. Tumor cell migration and invasion are enhanced by depletion of Rap1 GTPase-activating protein (Rap1GAP). J Biol Chem 2013; 288:24636-46. [PMID: 23864657 DOI: 10.1074/jbc.m113.464594] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The functional significance of the widespread down-regulation of Rap1 GTPase-activating protein (Rap1GAP), a negative regulator of Rap activity, in human tumors is unknown. Here we show that human colon cancer cells depleted of Rap1GAP are endowed with more aggressive migratory and invasive properties. Silencing Rap1GAP enhanced the migration of confluent and single cells. In the latter, migration distance, velocity, and directionality were increased. Enhanced migration was a consequence of increased endogenous Rap activity as silencing Rap expression selectively abolished the migration of Rap1GAP-depleted cells. ROCK-mediated cell contractility was suppressed in Rap1GAP-depleted cells, which exhibited a spindle-shaped morphology and abundant membrane protrusions. Tumor cells can switch between Rho/ROCK-mediated contractility-based migration and Rac1-mediated mesenchymal motility. Strikingly, the migration of Rap1GAP-depleted, but not control cells required Rac1 activity, suggesting that loss of Rap1GAP alters migratory mechanisms. Inhibition of Rac1 activity restored membrane blebbing and increased ROCK activity in Rap1GAP-depleted cells, suggesting that Rac1 contributes to the suppression of contractility. Collectively, these findings identify Rap1GAP as a critical regulator of aggressive tumor cell behavior and suggest that the level of Rap1GAP expression influences the migratory mechanisms that are operative in tumor cells.
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Affiliation(s)
- Oxana M Tsygankova
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6061, USA
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19
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Dong X, Tang W, Stopenski S, Brose MS, Korch C, Meinkoth JL. RAP1GAP inhibits cytoskeletal remodeling and motility in thyroid cancer cells. Endocr Relat Cancer 2012; 19:575-88. [PMID: 22696507 PMCID: PMC3531979 DOI: 10.1530/erc-12-0086] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The functional significance of decreased RAP1GAP protein expression in human tumors is unclear. To identify targets of RAP1GAP downregulation in the thyroid gland, RAP1 and RAP2 protein expression in human thyroid cells and in primary thyroid tumors were analyzed. RAP1GAP and RAP2 were co-expressed in normal thyroid follicular cells. Intriguingly, RAP1 was not detected in normal thyroid cells, although it was detected in papillary thyroid carcinomas, which also expressed RAP2. Both RAP proteins were detected at the membrane in papillary thyroid tumors, suggesting that they are activated when RAP1GAP is downregulated. To explore the functional significance of RAP1GAP depletion, RAP1GAP was transiently expressed at the lowest level that is sufficient to block endogenous RAP2 activity in papillary and anaplastic thyroid carcinoma cell lines. RAP1GAP impaired the ability of cells to spread and migrate on collagen. Although RAP1GAP had no effect on protein tyrosine phosphorylation in growing cells, RAP1GAP impaired phosphorylation of focal adhesion kinase and paxillin at sites phosphorylated by SRC in cells acutely plated on collagen. SRC activity was increased in suspended cells, where it was inhibited by RAP1GAP. Inhibition of SRC kinase activity impaired cell spreading and motility. These findings identify SRC as a target of RAP1GAP depletion and suggest that the downregulation of RAP1GAP in thyroid tumors enhances SRC-dependent signals that regulate cellular architecture and motility.
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Affiliation(s)
- Xiaoyun Dong
- Department of Pharmacology - Head and Neck Surgery, School of Medicine, University of Pennsylvania, 421 Curie Boulevard, BRB II/III, Philadelphia, PA 19104, USA
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20
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Machtaler S, Dang-Lawson M, Choi K, Jang C, Naus CC, Matsuuchi L. The gap junction protein Cx43 regulates B-lymphocyte spreading and adhesion. J Cell Sci 2011; 124:2611-21. [PMID: 21750189 DOI: 10.1242/jcs.089532] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The gap junction protein connexin43 (Cx43) is widely expressed in mammalian cells and forms intercellular channels for the transfer of small molecules between adjacent cells, as well as hemichannels that mediate bidirectional transport of molecules between the cell and the surrounding environment. Cx43 regulates cell adhesion and migration in neurons and glioma cells, and we now show that Cx43 influences BCR-, LFA-1- and CXCL12-mediated activation of the Rap1 GTPase. Using shRNA knockdown of Cx43 in WEHI 231 cells, we show that Cx43 is required for sustained Rap1 activation and BCR-mediated spreading. To determine the domains of Cx43 that are important for this effect, Cx43-null J558 μm3 B cells (which express a wild-type IgM BCR) were transfected with wild-type Cx43-GFP or a C-terminal-truncated Cx43 (Cx43ΔT-GFP). Expression of wild-type Cx43-GFP, but not Cx43ΔT-GFP, was sufficient to restore sustained, BCR-mediated Rap1 activation and cell spreading. Cx43, and specifically the C-terminal domain, was also important for LFA-1- and CXCL12-mediated Rap1 activation, spreading and adhesion to an endothelial cell monolayer. These data show that Cx43 has an important and previously unreported role in B-cell processes that are essential to normal B-cell development and immune responses.
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Affiliation(s)
- Steven Machtaler
- CELL and I³ Research Group, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
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21
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Vuchak LA, Tsygankova OM, Meinkoth JL. Rap1GAP impairs cell-matrix adhesion in the absence of effects on cell-cell adhesion. Cell Adh Migr 2011; 5:323-31. [PMID: 21785277 DOI: 10.4161/cam.5.4.17041] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The significance of the widespread downregulation of Rap1GAP in human tumors is unknown. In previous studies we demonstrated that silencing Rap1GAP expression in human colon cancer cells resulted in sustained increases in Rap activity, enhanced spreading on collagen and the weakening of cell-cell contacts. The latter finding was unexpected based on the role of Rap1 in strengthening cell-cell adhesion and reports that Rap1GAP impairs cell-cell adhesion. We now show that Rap1GAP is a more effective inhibitor of cell-matrix compared to cell-cell adhesion. Overexpression of Rap1GAP in human colon cancer cells impaired Rap2 activity and the ability of cells to spread and migrate on collagen IV. Under the same conditions, Rap1GAP had no effect on cell-cell adhesion. Overexpression of Rap1GAP did not enhance the dissociation of cell aggregates nor did it impair the accumulation of β-catenin and E-cadherin at cell-cell contacts. To further explore the role of Rap1GAP in the regulation of cell-cell adhesion, Rap1GAP was overexpressed in non-transformed thyroid epithelial cells. Although the formation of cell-cell contacts required Rap1, overexpression of Rap1GAP did not impair cell-cell adhesion. These data indicate that transient, modest expression of Rap1GAP is compatible with cell-cell adhesion and that the role of Rap1GAP in the regulation of cell-cell adhesion may be more complex than is currently appreciated.
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Affiliation(s)
- Lisa A Vuchak
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
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22
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Dong X, Korch C, Meinkoth JL. Histone deacetylase inhibitors upregulate Rap1GAP and inhibit Rap activity in thyroid tumor cells. Endocr Relat Cancer 2011; 18:301-10. [PMID: 21367844 PMCID: PMC3531977 DOI: 10.1530/erc-10-0320] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Increases in Rap activity have been associated with tumor progression. Although activating mutations in Rap have not been described, downregulation of Rap1GAP is frequent in human tumors including thyroid carcinomas. In this study, we explored whether endogenous Rap1GAP expression could be restored to thyroid tumor cells. The effects of deacetylase inhibitors and a demethylating agent, individually and in combination, were examined in four differentiated and six anaplastic thyroid carcinoma (ATC) cell lines. Treatment with the structurally distinct histone deacetylase (HDAC) inhibitors, sodium butyrate and trichostatin A, increased Rap1GAP expression in all the differentiated thyroid carcinoma cell lines and in four of the six ATC cell lines. The demethylating agent, 5-aza-deoxycytidine, restored Rap1GAP expression in one anaplastic cell line and enhanced the effects of HDAC inhibitors in a second anaplastic cell line. Western blotting indicated that Rap2 was highly expressed in human thyroid cancer cells. Importantly, treatment with HDAC inhibitors impaired Rap2 activity in both differentiated and anaplastic tumor cell lines. The mechanism through which Rap activity is repressed appears to entail effects on the expression of multiple Rap regulators, including RapGEFs and RapGAPs. These results suggest that HDAC inhibitors may provide a tractable approach to impair Rap activity in human tumor cells.
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Affiliation(s)
- Xiaoyun Dong
- Department of Pharmacology, School of Medicine, University of Pennsylvania, Philadelphia, 19104 Pennsylvania, USA
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23
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Lin KBL, Freeman SA, Gold MR. Rap GTPase-mediated adhesion and migration: A target for limiting the dissemination of B-cell lymphomas? Cell Adh Migr 2010; 4:327-32. [PMID: 20212359 DOI: 10.4161/cam.4.3.11114] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
B-cell lymphomas, which arise in lymphoid organs, can spread rapidly via the circulatory system and form solid tumors within multiple organs. Rate-limiting steps in this metastatic process may be the adhesion of lymphoma cells to vascular endothelial cells, their exit from the vasculature and their migration to tissue sites that will support tumor growth. Thus proteins that control B cell adhesion and migration are likely to be key factors in lymphoma dissemination, and hence potential targets for therapeutic intervention. The Rap GTPases are master regulators of integrin activation, cell motility and the underlying cytoskeletal, adhesion and membrane dynamics. We have recently shown that Rap activation is critical for B-lymphoma cells to undergo transendothelial migration in vitro and in vivo. As a consequence, suppressing Rap activation impairs the ability of intravenously injected B-lymphoma cells to form solid tumors in the liver and other organs. We discuss this work in the context of targeting Rap, its downstream effectors, or other regulators of B cell adhesion and migration as an approach for limiting the dissemination of B-lymphoma cells and the development of secondary tumors.
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Affiliation(s)
- Kevin B L Lin
- Department of Microbiology and Immunology and Life Sciences Institute I3 and CELL research groups, University of British Columbia, Vancouver, BC, Canada
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