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Peng X, Pentassuglia L, Sawyer DB. Emerging anticancer therapeutic targets and the cardiovascular system: is there cause for concern? Circ Res 2010; 106:1022-34. [PMID: 20360265 DOI: 10.1161/circresaha.109.211276] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The race for a cure to cancer continues, fueled by unprecedented discoveries of fundamental biology underlying carcinogenesis and tumorigenesis. The expansion of the target list and tools to approach them is moving the oncology community extraordinarily rapidly to clinical trials, bringing new hope for cancer patients. This effort is also propelling biological discoveries in cardiovascular research, because many of the targets being explored in cancer play fundamental roles in the heart and vasculature. The combined efforts of cardiovascular and cancer biologists, along with clinical investigators in these fields, will be needed to understand how to safely exploit these efforts. Here, we discuss a few of the many research foci in oncology where we believe such collaboration will be particularly important.
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Affiliation(s)
- Xuyang Peng
- Cardiovascular Medicine, Vanderbilt University Medical Center, PRB 359B Pierce Ave., Nashville, TN 37232, USA.
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2
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Hofmann C, Lippert E, Falk W, Schölmerich J, Rogler G, Obermeier F. Primary human colonic epithelial cells are transiently protected from anoikis by a Src-dependent mechanism. Biochem Biophys Res Commun 2009; 390:908-14. [PMID: 19852943 DOI: 10.1016/j.bbrc.2009.10.075] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Accepted: 10/16/2009] [Indexed: 12/19/2022]
Abstract
Complete loss of cell anchorage triggers apoptosis in primary human colonic epithelial cells (CEC), a phenomenon known as anoikis. Besides the induction of pro-apoptotic events, activation of survival pathways was observed in detached intestinal epithelial cell lines, providing a transient apoptosis protection. However, nothing is known about molecular mechanisms protecting primary CEC from anoikis. In this study intact CEC crypts were isolated and kept in suspension, a condition which leads to the loss of cell-cell anchorage and induces anoikis. To reconstitute cell-cell contacts, cells were centrifuged to form cell aggregates. Induction of apoptosis was assessed by caspase-3 activity assay; activation of survival pathways was analyzed by Western blot. Immediately after loss of cell anchorage a rapid activation of survival proteins was observed before active caspase-3 could be detected. Src hyperactivation significantly contributed to transient protection from anoikis in CEC because its inhibition reversed the protecting effect of re-establishment of cell contacts. Basal levels of active Src in CEC from patients with inflammatory bowel disease were markedly reduced compared to control patients. These results demonstrate that loss of cell anchorage activates survival pathways in primary human CEC providing transient anoikis protection. Src is an important mediator of this mechanism and therefore constitutes a key regulatory molecule coordinating survival signals mediated by cell adhesion in primary human CEC.
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Affiliation(s)
- Claudia Hofmann
- Department of Internal Medicine I, Regensburg University Medical Center, 93042 Regensburg, Germany.
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3
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Delbaldo C, Raymond E, Vera K, Hammershaimb L, Kaucic K, Lozahic S, Marty M, Faivre S. Phase I and pharmacokinetic study of etaracizumab (Abegrin), a humanized monoclonal antibody against alphavbeta3 integrin receptor, in patients with advanced solid tumors. Invest New Drugs 2007; 26:35-43. [PMID: 17876527 DOI: 10.1007/s10637-007-9077-0] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Accepted: 08/03/2007] [Indexed: 12/01/2022]
Abstract
This study assessed the safety, immunogenicity, and pharmacokinetics of etaracizumab, a monoclonal antibody directed against the alphavbeta3 integrin, in patients with advanced malignancies. Four cohorts of four patients received escalating dose of etaracizumab as a 30-min intravenous infusion, first as a single test dose, followed-up 2-5 weeks later by weekly doses. Sixteen patients with advanced solid tumors received a total of 309 cycles of etaracizumab at doses ranging 1-6 mg/kg. The mean number of weekly infusions was 19 (ranging 5-53). Frequently reported adverse events were grades 1-2 asthenia (15 patients) and infusion reactions (9 patients). At 1 mg/kg, one patient experienced grade 3 chills with the first infusion. Other grade 3 toxicities included reversible hyponatremia, hypophosphatemia and hyponatremia in one patient each at 1, 4 and 6 mg/kg, respectively. No patient experienced treatment delay/discontinuation due to an adverse event. The half-life of etaracizumab ranged 49-180 h with a nonlinear increase in terminal half-life with increasing doses. There was no objective response but five patients experienced a stable disease of >6-month duration. Etaracizumab was well-tolerated at doses up to 6 mg/kg with no evidence of immunogenicity. The safety profile of etaracizumab warrants further exploration in ongoing phase I/II trials.
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Affiliation(s)
- Catherine Delbaldo
- Department of Medical Oncology, Beaujon University Hospital, Clichy, France
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4
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Hofmann C, Obermeier F, Artinger M, Hausmann M, Falk W, Schoelmerich J, Rogler G, Grossmann J. Cell-cell contacts prevent anoikis in primary human colonic epithelial cells. Gastroenterology 2007; 132:587-600. [PMID: 17258732 DOI: 10.1053/j.gastro.2006.11.017] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2005] [Accepted: 10/26/2006] [Indexed: 12/13/2022]
Abstract
BACKGROUND & AIMS Colonic epithelial cells (CECs) receive important survival signals from the extracellular matrix and undergo detachment-induced apoptosis (anoikis) as soon as they lose their cell-matrix anchorage. In contrast to the established role of cell-matrix contact, the role of cell-cell contacts as a physiologic survival factor for CECs is less clear. METHODS Intact CEC crypts gently centrifuged to form a cell aggregate in which cell-cell contacts were maintained. Induction of apoptosis was assessed by Western Blot analysis, colorimetric assays, DNA electrophoresis, 4',6-diamidino-2-phenylindole staining, and flow cytometry. Activation of survival pathways was analyzed by Western blot. The role of mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK)/extracellular signal-regulated kinase (Erk)1/2, epidermal growth factor receptor, phosphatidylinositol 3-kinase (PI3-K), and Src signaling was investigated using specific inhibitors. RESULTS Despite a complete loss of cell-matrix adhesion after CEC isolation, activation of caspases was blocked and anoikis was prevented when cell-cell contacts were preserved. CECs with preserved cell-cell contacts exhibited a rapid dephosphorylation of focal adhesion kinase. Aggregated CECs had stable levels of active beta-catenin and phosphorylated Akt, Erk1/2, and epidermal growth factor receptor, but CECs undergoing anoikis rapidly degraded beta-catenin and dephosphorylated Akt. Inhibition of Src- and PI3-K-dependent signaling reversed the antiapoptotic effect of cell-cell contact preservation, while inhibition of the MEK pathway had no effect. CONCLUSIONS Integrity of cell-cell contacts compensates for the loss of cell-matrix contact-mediated survival signals in CECs and prevents apoptosis. Cell-cell contact-triggered CEC survival involves antiapoptotic signaling through beta-catenin-, Src-, and PI3-K/Akt- but not through MEK- and focal adhesion kinase-dependent pathways.
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Affiliation(s)
- Claudia Hofmann
- Department of Internal Medicine I, University of Regensburg, Regensburg, Germany
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5
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Defilippi P, Rosso A, Dentelli P, Calvi C, Garbarino G, Tarone G, Pegoraro L, Brizzi MF. {beta}1 Integrin and IL-3R coordinately regulate STAT5 activation and anchorage-dependent proliferation. ACTA ACUST UNITED AC 2005; 168:1099-108. [PMID: 15795318 PMCID: PMC2171831 DOI: 10.1083/jcb.200405116] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We previously demonstrated that integrin-dependent adhesion activates STAT5A, a well known target of IL-3–mediated signaling. Here, we show that in endothelial cells the active β1 integrin constitutively associates with the unphosphorylated IL-3 receptor (IL-3R) β common subunit. This association is not sufficient for activating downstream signals. Indeed, only upon fibronectin adhesion is Janus Kinase 2 (JAK2) recruited to the β1 integrin–IL-3R complex and triggers IL-3R β common phosphorylation, leading to the formation of docking sites for activated STAT5A. These events are IL-3 independent but require the integrity of the IL-3R β common. IL-3 treatment increases JAK2 activation and STAT5A and STAT5B tyrosine and serine phosphorylation and leads to cell cycle progression in adherent cells. Expression of an inactive STAT5A inhibits cell cycle progression upon IL-3 treatment, identifying integrin-dependent STAT5A activation as a priming event for IL-3–mediated S phase entry. Consistently, overexpression of a constitutive active STAT5A leads to anchorage-independent cell cycle progression. Therefore, these data provide strong evidence that integrin-dependent STAT5A activation controls IL-3–mediated proliferation.
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Affiliation(s)
- Paola Defilippi
- Department of Genetics, Biology and Biochemistry, University of Torino, 10126, Torino, Italy.
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6
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Sharma M, Sharma R, McCarthy ET, Savin VJ. The focal segmental glomerulosclerosis permeability factor: biochemical characteristics and biological effects. Exp Biol Med (Maywood) 2004; 229:85-98. [PMID: 14709781 DOI: 10.1177/153537020422900111] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) is characterized by steroid resistant nephrotic syndrome and progression to end-stage renal disease. Proteinuria in certain patients with FSGS may be caused by a circulating factor (FSGS permeability factor [FSPF]). The current report documents the biochemical characteristics and the biological and molecular effects of 70% ammonium sulfate supernatant of plasma from patients with recurrence of FSGS after transplantation (FSGS 70% supernatant). FS permeability activity, defined as the capacity of plasma from patients with FSGS to increase albumin permeability (P(alb)) of isolated glomeruli, was assessed in vitro. Permeability activity was not affected by lyophilization. FSPF bound strongly to matrices containing Mono-Q anion exchanger or protein A. It eluted from matrix-bound Cibacron blue F3GA over a wide range of salt concentrations, indicating a potential binding with other proteins, such as albumin. FSPF caused a maximal increase in P(alb) within 2 mins of incubation in vitro. Cellular proteins isolated from glomeruli with increased P(alb) showed decreased tyrosine phosphorylation of focal adhesion kinase, paxillin, and other proteins. Tyrosine phosphatase ]inhibition prevented the increase in P(alb). Intravenous administration of as little as 3 mg protein in FSGS 70% supernatant increased P(alb), while 9 mg or more were required to produce proteinuria. We conclude that FSPF is a low-molecular-weight protein, carries an anionic charge, and binds to protein A. Effects of FSPF on the glomerular permeability barrier are rapid and dose dependent and involve signaling through altered phosphorylation of cellular proteins. Identification of these biochemical and biological characteristics may be used to design strategies for removing FSPF from circulation and for purification and identification of this factor.
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Affiliation(s)
- Mukut Sharma
- Nephrology Division, Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
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7
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Baronas-Lowell D, Lauer-Fields JL, Fields GB. Induction of Endothelial Cell Activation by a Triple Helical α2β1 Integrin Ligand, Derived from Type I Collagen α1(I)496–507. J Biol Chem 2004; 279:952-62. [PMID: 14581484 DOI: 10.1074/jbc.m305989200] [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] [Indexed: 11/06/2022] Open
Abstract
Endothelial cell activation involves the elevated expression of cell adhesion molecules, chemoattractants, chemokines, and cytokines. These expression profiles may be regulated by integrin-mediated cell signaling pathways. In the current study, an alpha2beta1 integrin triple helical peptide ligand derived from type I collagen residues alpha1(I)496-507 was examined for induction of human aortic endothelial cell (HAEC) activation. In addition, a "miniextracellular matrix" composed of a mixture of the alpha1(I)496-507 ligand and a second, alpha-helical ligand incorporating the endothelial cell proliferating region of SPARC (secreted protein acidic and rich in cysteine) was studied for induction of HAEC activation. Following HAEC adhesion to alpha1(I)496-507, mRNA expression of E-selectin-1, vascular and intercellular cell adhesion molecules-1, and monocytic chemoattractant protein-1 was stimulated, whereas that of endothelin-1 was inhibited. Enzyme-linked immunosorbent assay analysis demonstrated that E-selectin-1 and monocytic chemoattractant protein-1 expression was also stimulated, whereas endothelin-1 protein expression diminished. Engagement of the alpha2beta1 integrin initiated a HAEC response similar to that of tumor necrosis factor-alpha-induced HAECs but was not sufficient to induce an inflammatory response. Addition of the SPARC119-122 region had only a slight effect on HAEC activation. Other cell-extracellular matrix interactions appear to be required to elicit an inflammatory response. The alpha2beta1 integrin specific triple helical peptide ligand described herein represents a more general in vitro model system by which gene expression and protein production profiles induced by binding to a single cellular receptor type can be quantified.
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Affiliation(s)
- Diane Baronas-Lowell
- Department of Chemistry and Biochemistry, Florida Atlantic University, Boca Raton, Florida 33431-0991, USA
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8
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Di Stefano P, Cabodi S, Boeri Erba E, Margaria V, Bergatto E, Giuffrida MG, Silengo L, Tarone G, Turco E, Defilippi P. P130Cas-associated protein (p140Cap) as a new tyrosine-phosphorylated protein involved in cell spreading. Mol Biol Cell 2003; 15:787-800. [PMID: 14657239 PMCID: PMC329393 DOI: 10.1091/mbc.e03-09-0689] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Integrin-mediated cell adhesion stimulates a cascade of signaling pathways that control cell proliferation, migration, and survival, mostly through tyrosine phosphorylation of signaling molecules. p130Cas, originally identified as a major substrate of v-Src, is a scaffold molecule that interacts with several proteins and mediates multiple cellular events after cell adhesion and mitogen treatment. Here, we describe a novel p130Cas-associated protein named p140Cap (Cas-associated protein) as a new tyrosine phosphorylated molecule involved in integrin- and epidermal growth factor (EGF)-dependent signaling. By affinity chromatography of human ECV304 cell extracts on a MBP-p130Cas column followed by mass spectrometry matrix-assisted laser desorption ionization/time of flight analysis, we identified p140Cap as a protein migrating at 140 kDa. We detected its expression in human, mouse, and rat cells and in different mouse tissues. Endogenous and transfected p140Cap proteins coimmunoprecipitate with p130Cas in ECV304 and in human embryonic kidney 293 cells and associate with p130Cas through their carboxy-terminal region. By immunofluorescence analysis, we demonstrated that in ECV304 cells plated on fibronectin, the endogenous p140Cap colocalizes with p130Cas in the perinuclear region as well as in lamellipodia. In addition p140Cap codistributes with cortical actin and actin stress fibers but not with focal adhesions. We also show that p140Cap is tyrosine phosphorylated within 15 min of cell adhesion to integrin ligands. p140Cap tyrosine phosphorylation is also induced in response to EGF through an EGF receptor dependent-mechanism. Interestingly expression of p140Cap in NIH3T3 and in ECV304 cells delays the onset of cell spreading in the early phases of cell adhesion to fibronectin. Therefore, p140Cap is a novel protein associated with p130Cas and actin cytoskeletal structures. Its tyrosine phosphorylation by integrin-mediated adhesion and EGF stimulation and its involvement in cell spreading on matrix proteins suggest that p140Cap plays a role in controlling actin cytoskeleton organization in response to adhesive and growth factor signaling.
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Affiliation(s)
- Paola Di Stefano
- Dipartimento di Genetica, Biologia e Biochimica, Università di Torino, 10126 Turin, Italy
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9
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Abstract
The article is a comprehensive review of the occurrence of hormetic dose-response relationships induced by inorganic agents, including toxic agents, of significant environmental and public health interest (e.g., arsenic, cadmium, lead, mercury, selenium, and zinc). Hormetic responses occurred in a wide range of biological models (i.e., plants, invertebrate and vertebrate animals) for a large and diverse array of endpoints. Particular attention was given to providing an assessment of the quantitative features of the dose-response relationships and underlying mechanisms that could account for the biphasic nature of the hormetic response. These findings indicate that hormetic responses commonly occur in appropriately designed experiments and are highly generalizeable with respect to biological model responses. The hormetic dose response should be seen as a reliable feature of the dose response for inorganic agents and will have an important impact on the estimated effects of such agents on environmental and human receptors.
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Affiliation(s)
- Edward J Calabrese
- Department of Environmental Health Sciences, Morrill Science Center, University of Massachusetts, Amherst, MA 01003, USA.
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10
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Wang Z, Newman WH. Smooth muscle cell migration stimulated by interleukin 6 is associated with cytoskeletal reorganization. J Surg Res 2003; 111:261-6. [PMID: 12850472 DOI: 10.1016/s0022-4804(03)00087-8] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
BACKGROUND Interleukin 6 (IL-6) is elevated in the arterial wall in atherosclerosis and restenosis after angioplasty. An important contributor to these pathologies is migration of vascular smooth muscle cells (VSMC), which is often associated with cytoskeletal reorganization initiated by growth factors and chemokines. We recently reported that IL-6 stimulated migration of VSMC. Here, we examined the cytoskeleton of VSMC and cytoskeletal associated proteins to determine potential mechanisms associated with IL-6 induced migration. MATERIALS AND METHODS Studies were performed in VSMC cultured from rat aortas. RESULTS IL-6 significantly stimulated VSMC migration. IL-6 induced actin polymerization, and tyrosine phosphorylation of focal adhesion-associated cytoskeletal proteins including focal adhesion kinase (FAK) and paxillin. Cytochalasin D, an inhibitor of actin polymerization, blocked phosphorylation of FAK and paxillin as well as cell motility induced by the cytokine. CONCLUSIONS Collectively, these data demonstrate for the first time that IL-6 stimulates VSMC motility which correlated with induction of actin cytoskeletal reorganization and tyrosine phosphorylation of FAK and paxillin.
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Affiliation(s)
- Zhongbiao Wang
- Division of Basic Medical Science and Department of Anesthesiology, Mercer Universtiy School of Medicine and Medical Center of Central Georgia, Macon, 31207, USA.
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11
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Bass MD, Humphries MJ. Cytoplasmic interactions of syndecan-4 orchestrate adhesion receptor and growth factor receptor signalling. Biochem J 2002; 368:1-15. [PMID: 12241528 PMCID: PMC1222989 DOI: 10.1042/bj20021228] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2002] [Revised: 09/19/2002] [Accepted: 09/20/2002] [Indexed: 12/23/2022]
Abstract
Syndecan-4 is a ubiquitous transmembrane proteoglycan that localizes to the focal adhesions of adherent cells and binds to a range of extracellular ligands, including growth factors and extracellular-matrix proteins. Engagement of syndecan-4 is essential for adhesion formation in cells adhering via certain integrins, and for cell proliferation and migration in response to growth factors. The cytoplasmic domain of syndecan-4 interacts with a number of signalling and structural proteins, and both extracellular and cytoplasmic domains are necessary for regulated activation of associated transmembrane receptors. PDZ domain-containing scaffold proteins (syntenin and CASK) bind to the C-terminus of the syndecan-4 cytoplasmic domain and co-ordinate clustering of receptors and connection to the actin cytoskeleton. Syndecan-4 also binds and activates protein kinase Calpha in the presence of phosphatidylinositol 4,5-bisphosphate, and regulates signalling by Rho-family GTPases and focal adhesion kinase. This review discusses the cytoplasmic interactions of syndecan-4 and how they affect cell behaviour as a consequence of the interaction with extracellular ligands. These conclusions also offer an insight into the role of syndecan-4 in vivo, and are consistent with phenotypes generated as a consequence of abnormal syndecan-4 expression in pathologies and gene disruption studies.
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Affiliation(s)
- Mark D Bass
- Wellcome Trust Centre for Cell-Matrix Research, School of Biological Sciences, University of Manchester, Manchester M13 9PT, U.K
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12
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Windham TC, Parikh NU, Siwak DR, Summy JM, McConkey DJ, Kraker AJ, Gallick GE. Src activation regulates anoikis in human colon tumor cell lines. Oncogene 2002; 21:7797-807. [PMID: 12420216 DOI: 10.1038/sj.onc.1205989] [Citation(s) in RCA: 153] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2002] [Revised: 08/20/2002] [Accepted: 08/20/2002] [Indexed: 12/18/2022]
Abstract
Src is a non-receptor protein tyrosine kinase, the expression and activity of which is increased in >80% of human colon cancers with respect to normal colonic epithelium. Previous studies from this and other laboratories have demonstrated that Src activity contributes to tumorigenicity of established colon adenocarcinoma cell lines. Src participates in the regulation of many signal transduction pathways, among which are those leading to cellular survival. In this study, we addressed the potential role of Src activation to a specific aspect of tumor cell survival, resistance to detachment-induced apoptosis (anoikis). Using five colon tumor cell lines with different biologic properties and genetic alterations, we demonstrate that expression and activity of Src corresponds with resistance to anoikis. Enforced expression of activated Src in subclones of SW480 cells (of low intrinsic Src expression and activity) increases resistance to anoikis; whereas decreased Src expression in HT29 cells (of high Src expression and activity) by transfection with anti-sense Src expression vectors increases susceptibility to anoikis. In contrast, increasing or decreasing Src expression had no effect on susceptibility to staurosporine-induced apoptosis in attached cells. PD173955, a Src family-specific tyrosine kinase inhibitor, increases the susceptibility of HT29 cells to anoikis in a dose- and time-dependent manner. Increasing Src expression and activity led to increased phosphorylation of Akt, a mediator of cellular survival pathways, whereas decreasing Src activity led to decreased Akt phosphorylation. In colon tumor cells with high Src activity, the PI3 kinase inhibitor LY 294002 sensitized cells to anoikis. These results suggest that Src activation may contribute to colon tumor progression and metastasis in part by activating Akt-mediated survival pathways that decrease sensitivity of detached cells to anoikis.
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Affiliation(s)
- T Christopher Windham
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, Texas, TX 77030, USA
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13
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Rigacci S, Rovida E, Dello Sbarba P, Berti A. Low Mr phosphotyrosine protein phosphatase associates and dephosphorylates p125 focal adhesion kinase, interfering with cell motility and spreading. J Biol Chem 2002; 277:41631-6. [PMID: 12055185 DOI: 10.1074/jbc.m201709200] [Citation(s) in RCA: 37] [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
Low M(r) phosphotyrosine protein phosphatase interferes in vivo with the activation of several growth factor receptors and is transiently redistributed, following cell stimulation with platelet-derived growth factor, from the cytosol to the cytoskeleton. We demonstrate here that this phosphatase also participates in the regulation of cell spreading and migration, pointing to its involvement in cytoskeleton organization. Low M(r) phosphotyrosine protein phosphatase-overexpressing fibroblasts are, indeed, less spread than controls and display a significantly decreased number of focal adhesions and increased cell motility. Furthermore, p125 focal adhesion kinase is associated to, and dephosphorylated by, low M(r) phosphotyrosine protein phosphatase both in vitro and in vivo. This event is consistent with an altered association of pp60(src) with focal adhesion kinase. The activation of extracellular signal-regulated kinase, another well known event downstream of the focal adhesion kinase, is also affected. On the other hand, cells overexpressing the dominant-negative form of low M(r) phosphotyrosine protein phosphatase exhibit hyperphosphorylated focal adhesion kinase, reduced motility, and an increased number of focal adhesions, which are distributed all over the ventral cell surface. Taken together, the results reported here are in keeping with low M(r) phosphotyrosine protein phosphatase participation in FAK-mediated focal adhesion remodeling.
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Affiliation(s)
- Stefania Rigacci
- Department of Biochemical Sciences, University of Florence, Viale Morgagni 50, Italy
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14
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Santoni G, Lucciarini R, Amantini C, Jacobelli J, Spreghini E, Ballarini P, Piccoli M, Gismondi A. Candida albicans expresses a focal adhesion kinase-like protein that undergoes increased tyrosine phosphorylation upon yeast cell adhesion to vitronectin and the EA.hy 926 human endothelial cell line. Infect Immun 2002; 70:3804-15. [PMID: 12065524 PMCID: PMC128043 DOI: 10.1128/iai.70.7.3804-3815.2002] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The signaling pathways triggered by adherence of Candida albicans to the host cells or extracellular matrix are poorly understood. We provide here evidence in C. albicans yeasts of a p105 focal adhesion kinase (Fak)-like protein (that we termed CaFak), antigenically related to the vertebrate p125Fak, and its involvement in integrin-like-mediated fungus adhesion to vitronectin (VN) and EA.hy 926 human endothelial cell line. Biochemical analysis with different anti-chicken Fak antibodies identified CaFak as a 105-kDa protein and immunofluorescence and cytofluorimetric analysis on permeabilized cells specifically stain C. albicans yeasts; moreover, confocal microscopy evidences CaFak as a cytosolic protein that colocalizes on the membrane with the integrin-like VN receptors upon yeast adhesion to VN. The protein tyrosine kinase (PTK) inhibitors genistein and herbimycin A strongly inhibited C. albicans yeast adhesion to VN and EA.hy 926 endothelial cells. Moreover, engagement of alpha v beta 3 and alpha v beta 5 integrin-like on C. albicans either by specific monoclonal antibodies or upon adhesion to VN or EA.hy 926 endothelial cells stimulates CaFak tyrosine phosphorylation that is blocked by PTK inhibitor. A role for CaFak in C. albicans yeast adhesion was also supported by the failure of VN to stimulate its tyrosine phosphorylation in a C. albicans mutant showing normal levels of CaFak and VNR-like integrins but displaying reduced adhesiveness to VN and EA.hy 926 endothelial cells. Our results suggest that C. albicans Fak-like protein is involved in the control of yeast cell adhesion to VN and endothelial cells.
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Affiliation(s)
- Giorgio Santoni
- Department of Pharmacological Sciences and Experimental Medicine, University of Camerino, 62032 Camerino, Italy.
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15
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Moro L, Dolce L, Cabodi S, Bergatto E, Boeri Erba E, Smeriglio M, Turco E, Retta SF, Giuffrida MG, Venturino M, Godovac-Zimmermann J, Conti A, Schaefer E, Beguinot L, Tacchetti C, Gaggini P, Silengo L, Tarone G, Defilippi P. Integrin-induced epidermal growth factor (EGF) receptor activation requires c-Src and p130Cas and leads to phosphorylation of specific EGF receptor tyrosines. J Biol Chem 2002; 277:9405-14. [PMID: 11756413 DOI: 10.1074/jbc.m109101200] [Citation(s) in RCA: 283] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Integrin-mediated cell adhesion cooperates with growth factor receptors in the control of cell proliferation, cell survival, and cell migration. One mechanism to explain these synergistic effects is the ability of integrins to induce phosphorylation of growth factor receptors, for instance the epidermal growth factor (EGF) receptor. Here we define some aspects of the molecular mechanisms regulating integrin-dependent EGF receptor phosphorylation. We show that in the early phases of cell adhesion integrins associate with EGF receptors on the cell membrane in a macromolecular complex including the adaptor protein p130Cas and the c-Src kinase, the latter being required for adhesion-dependent assembly of the macromolecular complex. We also show that the integrin cytoplasmic tail, c-Src kinase, and the p130Cas adaptor protein are required for phosphorylation of EGF receptor in response to integrin-mediated adhesion. We show that integrins induce phosphorylation of EGF receptor on tyrosine residues 845, 1068, 1086, and 1173, but not on residue 1148, a major site of phosphorylation in response to EGF. In addition we find that integrin-mediated adhesion increases the amount of EGF receptor expressed on the cell surface. Therefore these data indicate that integrin-mediated adhesion induces assembly of a macromolecular complex containing c-Src and p130Cas and leads to phosphorylation of specific EGF receptor tyrosine residues.
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Affiliation(s)
- Laura Moro
- Dipartimento di Scienze Mediche, Università del Piemonte Orientale, Novara 28100, Italy
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16
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Interaction of endostatin with integrins implicated in angiogenesis. Proc Natl Acad Sci U S A 2001. [PMID: 11158588 PMCID: PMC14702 DOI: 10.1073/pnas.031564998] [Citation(s) in RCA: 165] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Endostatin, a fragment of collagen XVIII, is a potent antagonist of angiogenesis and inhibitor of tumor growth in mouse models. At present, the mechanism of action of endostatin is unknown. We show here that recombinantly produced human endostatin interacts with alpha(5)- and alpha(v)-integrins on the surface of human endothelial cells. We further demonstrate that the endostatin-integrin interaction is of functional significance in vitro, as we found that immobilized endostatin supports endothelial cell survival and migration in an integrin-dependent manner. Soluble endostatin in turn inhibits integrin-dependent endothelial cell functions, such as cell migration. Taken together, these results implicate integrins as potential targets for endostatin function and support the importance of integrins in endothelial cell biology and angiogenesis.
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17
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Rehn M, Veikkola T, Kukk-Valdre E, Nakamura H, Ilmonen M, Lombardo C, Pihlajaniemi T, Alitalo K, Vuori K. Interaction of endostatin with integrins implicated in angiogenesis. Proc Natl Acad Sci U S A 2001; 98:1024-9. [PMID: 11158588 PMCID: PMC14702 DOI: 10.1073/pnas.98.3.1024] [Citation(s) in RCA: 269] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Endostatin, a fragment of collagen XVIII, is a potent antagonist of angiogenesis and inhibitor of tumor growth in mouse models. At present, the mechanism of action of endostatin is unknown. We show here that recombinantly produced human endostatin interacts with alpha(5)- and alpha(v)-integrins on the surface of human endothelial cells. We further demonstrate that the endostatin-integrin interaction is of functional significance in vitro, as we found that immobilized endostatin supports endothelial cell survival and migration in an integrin-dependent manner. Soluble endostatin in turn inhibits integrin-dependent endothelial cell functions, such as cell migration. Taken together, these results implicate integrins as potential targets for endostatin function and support the importance of integrins in endothelial cell biology and angiogenesis.
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Affiliation(s)
- M Rehn
- Cancer Research Center, The Burnham Institute, La Jolla, CA 92037, USA
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18
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Fields GB, Lauer JL, Dori Y, Forns P, Yu YC, Tirrell M. Protein-like molecular architecture: biomaterial applications for inducing cellular receptor binding and signal transduction. Biopolymers 2000; 47:143-51. [PMID: 9703769 DOI: 10.1002/(sici)1097-0282(1998)47:2<143::aid-bip3>3.0.co;2-u] [Citation(s) in RCA: 139] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The development of biomaterials with desirable biocompatibility has presented a difficult challenge for tissue engineering researchers. First and foremost, materials themselves tend to be hydrophobic and/or thrombogenic in nature, and face compatibility problems upon implantation. To mediate this problem, researchers have attempted to graft protein fragments onto biomaterial surfaces to promote endothelial cell attachment and minimize thrombosis. We envisioned a novel approach, based on the capability of biomolecules to self-assemble into well-defined and intricate structures, for creating biomimetic biomaterials that promote cell adhesion and proliferation. One of the most intriguing self-assembly processes is the folding of peptide chains into native protein structures. We have developed a method for building protein-like structural motifs that incorporate sequences of biological interest. A lipophilic moiety is attached onto a N alpha-amino group of peptide chain, resulting in a "peptide-amphiphile." The alignment of amphiphilic compounds at the lipid-solvent interface is used to facilitate peptide alignment and structure initiation and propagation, while the lipophilic region absorbs to hydrophobic surfaces. Peptide-amphiphiles containing potentially triple-helical or alpha-helical structural motifs have been synthesized. The resultant head group structures have been characterized by CD spectroscopy and found to be thermally stable over physiological temperature ranges. Triple-helical peptide-amphiphiles have been applied to studies of surface modification and cell receptor binding. Cell adhesion and spreading was promoted by triple-helical peptide-amphiphiles. Cellular interaction with the type IV collagen sequence alpha 1(IV) 1263-1277 increased signal transduction, with both the time and level of induction dependent upon triple-helical conformation. Collectively, these results suggest that peptide-amphiphiles may be used to form stable molecular structure on biomaterial surfaces that promote cellular activities and improve biocompatibility.
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Affiliation(s)
- G B Fields
- Department of Chemistry and Biochemistry, Florida Atlantic University, Boca Raton 33431, USA
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19
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Zhou L, Cheng EL, Rege P, Yue BY. Signal transduction mediated by adhesion of human trabecular meshwork cells to extracellular matrix. Exp Eye Res 2000; 70:457-65. [PMID: 10865994 DOI: 10.1006/exer.1999.0806] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In this study we investigated the signaling event induced by adhesion of human trabecular meshwork (TM) cells to extracellular matrix (ECM) elements such as fibronectin. The role of tyrosine phosphorylation in adhesion was evaluated. A number of intracellular entities involved in the adhesion-mediated pathways were identified. For the experiments, human TM cells were seeded onto fibronectin- or polylysine (negative control)-coated plates. Fifteen, 30, 90 and 240 min after the seeding, cell lysates were collected. Immunoblotting analysis revealed that tyrosine phosphorylation occurred within 15 min of adhesion of TM cells to fibronectin and the level increased with time. The phosphotyrosyl proteins had molecular masses 25-220 kDa. A much lower level of tyrosine phosphorylation was observed when cells were plated on polylysine. Immunoprecipitation experiments indicated that the phosphotyrosine-containing proteins included focal adhesion kinase, paxillin, phosphatidylinositol 3-kinase and mitogen activated protein kinase. Within 30 min of adherence to fibronectin, human TM cells immunostained for paxillin and phosphotyrosine and exhibited prominent focal contacts. When treated with tyrosine kinase inhibitors genistein and herbimycin A and a protein kinase C (PKC) pseudosubstrate peptide inhibitor, cell adhesion to fibronectin was compromised and focal contact formation was limited. These results demonstrated that in human TM cells, tyrosine kinase was activated upon their adherence to fibronectin. PKC also appeared to play a role in modulation of the cell-matrix adhesion process. The current study provides insight into the signaling pathways that are linked to the ECM-induced events in TM cells. Elucidation of the hierarchy of signal responses may help develop strategies manipulating the cell-matrix interactions in the TM system.
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Affiliation(s)
- L Zhou
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago College of Medicine, USA
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20
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Belisario MA, Tafuri S, Di Domenico C, Squillacioti C, Della Morte R, Lucisano A, Staiano N. H(2)O(2) activity on platelet adhesion to fibrinogen and protein tyrosine phosphorylation. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1495:183-93. [PMID: 10656975 DOI: 10.1016/s0167-4889(99)00160-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Platelets represent a target of reactive oxygen species produced under oxidative stress conditions. Controversial data on the effect of these species on platelet functions have been reported so far. In this study we evaluated the effect of a wide range of H(2)O(2) concentrations on platelet adhesion to immobilized fibrinogen and on pp72(syk) and pp125(FAK) tyrosine phosphorylation. Our results demonstrate that: (1) H(2)O(2) does not affect the adhesion of unstimulated or apyrase-treated platelets to immobilized fibrinogen; (2) H(2)O(2) does not affect pp72(syk) phosphorylation induced by platelet adhesion to fibrinogen-coated dishes; (3) H(2)O(2) reduces, in a dose-dependent fashion, pp125(FAK) phosphorylation of fibrinogen-adherent platelets; (4) concentrations of H(2)O(2) near to physiological values (10-12 microM) are able to strengthen the subthreshold activation of pp125(FAK) induced by epinephrine in apyrase-treated platelets; (5) H(2)O(2) doses higher than 0.1 mM inhibit ADP-induced platelet aggregation and dense granule secretion. The ability of H(2)O(2) to modulate pp125(FAK) phosphorylation suggests a role of this molecule in physiological hemostasis as well as in thrombus generation.
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Affiliation(s)
- M A Belisario
- Dipartimento di Biochimica e Biotecnologie Mediche, Università di Napoli Federico II, Via S. Pansini 5, 80131, Naples, Italy.
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21
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Klein-Soyer C, Azorsa DO, Cazenave JP, Lanza F. CD9 participates in endothelial cell migration during in vitro wound repair. Arterioscler Thromb Vasc Biol 2000; 20:360-9. [PMID: 10669631 DOI: 10.1161/01.atv.20.2.360] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
CD9, a widely expressed membrane protein of the tetraspanin family, has been implicated in diverse functions, such as signal transduction, cell adhesion, and cell motility. We tested the effects of an anti-CD9 monoclonal antibody (ALMA.1) on the migration and proliferation of human vascular endothelial cells (ECs) during repair of an in vitro mechanical wound mimicking angiogenic processes. ALMA.1 induced dose-dependent inhibition of wound repair with a 35+/-1.5% decrease at 20 microg/mL. Only cell migration was affected, because the rate of proliferation of ECs at the lesion margin was not modified and because the inhibition of repair was also observed for nonproliferating irradiated ECs. Monoclonal antibodies against CD63 tetraspanin (H5C6) and control mouse IgG (MOPC-21) were inactive. CD9, one of the most abundant proteins at the surface of ECs, colocalized with beta(1) or beta(3) integrins on EC membranes in double-labeling immunofluorescence experiments with ALMA.1 and an anti-beta(1) (4B4) or anti-beta(3) (SDF.3) monoclonal antibody. Moreover, ALMA.1 and 4B4 had additive inhibitory effects on lesion repair, whereas 4B4 alone also inhibited EC proliferation. In transmembrane Boyden-type assays, ALMA.1 induced dose-dependent inhibition of EC migration toward fibronectin and vitronectin with 45+/-6% and 31+/-10% inhibition, respectively, at 100 microg/mL. 4B4 inhibited migration toward fibronectin at 10 microg/mL but had no effect in the case of vitronectin. Adhesion of ECs to immobilized anti-CD9 monoclonal antibodies induced tyrosine-phosphorylated protein levels similar to those observed during interactions with beta(1) or beta(3) integrins. These results point to the involvement of CD9 in EC adhesion and migration during lesion repair and angiogenesis, probably through cooperation with integrins. As such, CD9 is a potential target to inhibit angiogenesis in metastatic and atherosclerotic processes.
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Affiliation(s)
- C Klein-Soyer
- INSERM U. 311, Etablissement de Transfusion Sanguine de Strasbourg Strasbourg, France.
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22
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Petit V, Boyer B, Thiery JP, Vallés AM. Characterization of the signaling pathways regulating alpha2beta1 integrin-mediated events by a pharmacological approach. CELL ADHESION AND COMMUNICATION 2000; 7:151-65. [PMID: 10626901 DOI: 10.3109/15419069909010799] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
In certain instances of developing and adult organism, epithelial cells can change morphology and transform into mesenchymal-like type in order to move through the extracellular matrix. However, because of the multiplicity and complexity of signaling pathways that contribute to these processes, their molecular dissection has remained difficult. By using a pharmacological approach on the rat bladder carcinoma cell line NBT-II dispersion system, we have identified distinct signaling events for adhesion and motility in response to collagen, both activities depending on alpha2beta1 integrin. Treatment of cells with PKC inhibitors markedly impaired initial attachment on collagen without affecting the capacity of cells to move, suggesting that PKC activity is required for initial adhesion strength during cell translocation. Both adhesion and motility were diminished by tyrosine kinase inhibitors herbimycin and tyrphostin whereas tyrosine phosphatase inhibitors amplified cell scattering. The collagen-induced dispersion was insensitive to genistein which we previously showed to abrogate growth factor-induced scattering, thus demonstrating inducer specificity. Finally. Ras inhibitors and expression of a dominant negative form of Ras (N17Ras) while affecting initial cell attachment, did not prevent cell migration, and instead favored the dissociated state on collagen. The specific signaling pathways identified for adhesion and motility should help to understand the sequential processes associated with cell migration.
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Affiliation(s)
- V Petit
- UMR 144, CNRS, Subcellular Structure and Cellular Dynamics, Institut Curie Research Division, Paris, France
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23
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Defilippi P, Olivo C, Venturino M, Dolce L, Silengo L, Tarone G. Actin cytoskeleton organization in response to integrin-mediated adhesion. Microsc Res Tech 1999; 47:67-78. [PMID: 10506763 DOI: 10.1002/(sici)1097-0029(19991001)47:1<67::aid-jemt7>3.0.co;2-p] [Citation(s) in RCA: 131] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Cell matrix adhesion regulates actin cytoskeleton organization through distinct steps, from formation of filopodia and lamellipodia in the early phases of cell adhesion to organization of focal adhesions and stress fibers in fully adherent cells. In this review, we follow the events induced by integrin-mediated adhesion, such as activation of GTPases Cdc42 and Rac and their effectors and their role in actin polymerization leading to formation of lamellipodia and filopodia and cell spreading. We also show that actin stress fiber and focal adhesion formation following adhesion requires cooperation between integrin-mediated signaling and additional stimuli, including activation of PKC, Rho GTPases, and PTKs such as p125Fak and Src.
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Affiliation(s)
- P Defilippi
- Dipartimento di Genetica, Biologia e Biochimica, Università di Torino, Torino, Italy.
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24
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Brizzi MF, Defilippi P, Rosso A, Venturino M, Garbarino G, Miyajima A, Silengo L, Tarone G, Pegoraro L. Integrin-mediated adhesion of endothelial cells induces JAK2 and STAT5A activation: role in the control of c-fos gene expression. Mol Biol Cell 1999; 10:3463-71. [PMID: 10512880 PMCID: PMC25616 DOI: 10.1091/mbc.10.10.3463] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Integrin-mediated adhesion induces several signaling pathways leading to regulation of gene transcription, control of cell cycle entry and survival from apoptosis. Here we investigate the involvement of the Janus kinase (JAK)/signal transducers and activators of transcription (STAT) pathway in integrin-mediated signaling. Plating primary human endothelial cells from umbilical cord and the human endothelial cell line ECV304 on matrix proteins or on antibody to beta1- or alphav-integrin subunits induces transient tyrosine phosphorylation of JAK2 and STAT5A. Consistent with a role for the JAK/STAT pathway in regulation of gene transcription, adhesion to matrix proteins leads to the formation of STAT5A-containing complexes with the serum-inducible element of c-fos promoter. Stable expression of a dominant negative form of STAT5A in NIH3T3 cells reduces fibronectin-induced c-fos mRNA expression, indicating the involvement of STAT5A in integrin-mediated c-fos transcription. Thus these data present a new integrin-dependent signaling mechanism involving the JAK/STAT pathway in response to cell-matrix interaction.
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Affiliation(s)
- M F Brizzi
- Department of Internal Medicine, Biology, and Biochemistry, University of Torino, 10126 Torino, Italy
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25
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Hassid A, Yao J, Huang S. NO alters cell shape and motility in aortic smooth muscle cells via protein tyrosine phosphatase 1B activation. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:H1014-26. [PMID: 10484424 DOI: 10.1152/ajpheart.1999.277.3.h1014] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cell motility is an important determinant of vascular disease. We examined mechanisms underlying the effect of nitric oxide (NO) on motility in cultured primary aortic smooth muscle cells from newborn rats. The NO donor S-nitroso-N-acetyl-penicillamine (SNAP) increased the activity of protein tyrosine phosphatase 1B (PTP-1B). This effect was mimicked by a cGMP analog and blocked by the guanyl cyclase antagonist 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, indicating the involvement of cGMP. Treatment of cells with antisense, but not control oligodeoxynucleotide (ODN), against PTP-1B attenuated the inhibitory effect of NO on cell motility. Cell shape and adhesion are important determinants of cell motility. We report that SNAP induced cell rounding and reduced adhesion and caused dissociation of actin stress fibers. Moreover, SNAP reduced phosphotyrosine levels in focal adhesion proteins, paxillin, and focal adhesion kinase. The PTP inhibitor phenylarsine oxide or decrease of PTP-1B protein levels via the use of antisense ODN prevented NO-induced cell-shape change, altered adhesion, and migration. These results indicate that NO regulates cell shape, adhesion, and migration by dephosphorylation of focal adhesion proteins via a mechanism that requires PTP-1B activity.
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Affiliation(s)
- A Hassid
- Department of Physiology, University of Tennessee, Memphis, Tennessee 38163, USA.
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26
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Berge N, Loganadane LD, Vassy J, Monnet E, Legrand C, Fauvel-Lafeve F. Adhesion-induced intracellular signalling in endothelial cells depends on the nature of the matrix. CELL ADHESION AND COMMUNICATION 1999; 7:29-41. [PMID: 10228733 DOI: 10.3109/15419069909034390] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The adhesion of a human microvascular endothelial cell line to its own matrix was studied in comparison with adhesion of the same cells to fibronectin or thrombospondin-1. These endothelial cells adhered preferentially to their matrix whereas an equal cell number was attached to fibronectin or thrombospondin-1. The adhesion of cells to thrombospondin-1 was mediated by the N-terminal heparin binding domain of thrombospondin-1 as shown by the use of a recombinant fragment, N18. Cells adhering to their matrix displayed a morphology and a cytoskeleton organization very similar to that observed in vivo with an apical immunostaining for actin stress fibers and a fine basal labeling for vinculin. Cells on fibronectin were extensively spread and rapidly assembled stress fibers and focal contacts. Cells adherent to thrombospondin-1 presented large lamellae rich in actin but devoid of vinculin and only few actin fibers were observed. Depending on the substratum used, adhering endothelial cells displayed also different tyrosine phosphorylation patterns on electrophoresis. Our observations indicate that endothelial cells adhering to their matrix present an activation state intermediate between that induced by a "hyperadhesive" protein like fibronectin and that generated by a moderate, indeed anti-adhesive, protein like thrombospondin-1.
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Affiliation(s)
- N Berge
- U353 INSERM: Protéines Adhésives et Protéases des Cellules Vasculaires et Sanguines, Hôpital Saint-Louis, Paris, France
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27
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Moro L, Venturino M, Bozzo C, Silengo L, Altruda F, Beguinot L, Tarone G, Defilippi P. Integrins induce activation of EGF receptor: role in MAP kinase induction and adhesion-dependent cell survival. EMBO J 1998; 17:6622-32. [PMID: 9822606 PMCID: PMC1171008 DOI: 10.1093/emboj/17.22.6622] [Citation(s) in RCA: 441] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Adhesion of human primary skin fibroblasts and ECV304 endothelial cells to immobilized matrix proteins, beta1 or alphav integrin antibodies stimulates tyrosine phosphorylation of the epidermal growth factor (EGF) receptor. This tyrosine phosphorylation is transiently induced, reaching maximal levels 30 min after adhesion, and it occurs in the absence of receptor ligands. Similar results were observed with EGF receptor-transfected NIH-3T3 cells. Use of a kinase-negative EGF receptor mutant demonstrates that the integrin-stimulated tyrosine phosphorylation is due to activation of the receptor's intrinsic kinase activity. Integrin-mediated EGF receptor activation leads to Erk-1/MAP kinase induction, as shown by treatment with the specific inhibitor tyrphostin AG1478 and by expression of a dominant-negative EGF receptor mutant. EGF receptor and Erk-1/MAP kinase activation by integrins does not lead per se to cell proliferation, but is important for entry into S phase in response to EGF or serum. EGF receptor activation is also required for extracellular matrix-mediated cell survival. Adhesion-dependent MAP kinase activation and survival are regulated through EGF receptor activation in cells expressing this molecule above a threshold level (5x10(3) receptors per cell). These results demonstrate that integrin-dependent EGF receptor activation is a novel signaling mechanism involved in cell survival and proliferation in response to extracellular matrix.
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Affiliation(s)
- L Moro
- Dipartimento di Scienze Mediche, Biochimica, Universitá di Torino, Italy
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28
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Motamed K, Sage EH. SPARC inhibits endothelial cell adhesion but not proliferation through a tyrosine phosphorylation-dependent pathway. J Cell Biochem 1998; 70:543-52. [PMID: 9712151 DOI: 10.1002/(sici)1097-4644(19980915)70:4<543::aid-jcb10>3.0.co;2-i] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
SPARC, a counteradhesive matricellular protein, inhibits endothelial cell adhesion and proliferation, but the pathways through which these activities are blocked are not known. In this study, we used inhibitors of major signaling proteins to identify mediators through which SPARC exerts its counteradhesive and antiproliferative functions. Pretreatments with the general protein tyrosine kinase (PTK) inhibitors, herbimycin A and genistein, protected against the inhibitory effect of SPARC on bovine aortic endothelial (BAE) cell spreading by more than 60%. Similar pretreatments with PTK inhibitors significantly blocked the diminishment of focal adhesions by SPARC in confluent BAE cell monolayers, as determined by the formation of actin stress-fibers and the distribution of vinculin in focal adhesion plaques. Inhibition of endothelial cell cycle progression by SPARC and a calcium-binding SPARC peptide, however, was not affected by PTK inhibitors. Inhibition of DNA synthesis by SPARC was not reversed by inhibitors of the activity of protein kinase C (PKC), or of cAMP-dependent protein kinase (PKA), but was sensitive to pertussis (and to a lesser extent, cholera) toxin. The counteradhesive effect of SPARC on endothelial cells is, therefore, mediated through a tyrosine phosphorylation-dependent pathway, whereas its antiproliferative function is dependent, in part, on signal transduction via a G protein-coupled receptor.
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Affiliation(s)
- K Motamed
- Department of Biological Structure, School of Medicine, University of Washington, Seattle 98195-7420, USA
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29
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Daly N, Meleady P, Walsh D, Clynes M. Regulation of keratin and integrin gene expression in cancer and drug resistance. Cytotechnology 1998; 27:321-44. [PMID: 19002802 PMCID: PMC3449561 DOI: 10.1023/a:1008066216490] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Affiliation(s)
- N Daly
- National Cell and Tissue Culture Centre, BioResearch Ireland, Dublin City University, Glasnevin, Dublin 9, Ireland.,
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30
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Vilgrain I, Chinn A, Gaillard I, Chambaz EM, Feige JJ. Hormonal regulation of focal adhesions in bovine adrenocortical cells: induction of paxillin dephosphorylation by adrenocorticotropic hormone. Biochem J 1998; 332 ( Pt 2):533-40. [PMID: 9601084 PMCID: PMC1219510 DOI: 10.1042/bj3320533] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A study of bovine adrenocortical cell shape on adrenocorticotropic hormone (ACTH) challenge showed that the cells round up and develop arborized processes. This effect was found to be (1) specific for ACTH because angiotensin II and basic fibroblast growth factor have no effect; (2) mediated by a cAMP-dependent pathway because forskolin reproduces the effect of the hormone; (3) inhibited by sodium orthovanadate, a phosphotyrosine phosphatase inhibitor, but unchanged by okadaic acid, a serine/threonine phosphatase inhibitor; and (4) correlated with a complete loss of focal adhesions. Biochemical studies of the focal-adhesion-associated proteins showed that pp125fak, vinculin (110 kDa) and paxillin (70 kDa) were detected in the Triton X-100-insoluble fraction from adrenocortical cells. During cell adhesion on fibronectin as substratum, two major phosphotyrosine-containing proteins of molecular masses 125 and 68 kDa were immunodetected in the same fraction. A dramatic decrease in the extent of tyrosine phosphorylation of these proteins was observed within 60 min after treatment with ACTH. No change in pp125fak tyrosine phosphorylation nor in Src activity was detected. In contrast, paxillin was found to be tyrosine-dephosphorylated in a time-dependent manner in ACTH-treated cells. Sodium orthovanadate completely prevented the effect of ACTH. These observations suggest a possible role for phosphotyrosine phosphatases in hormone-dependent cellular regulatory processes.
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Affiliation(s)
- I Vilgrain
- Unité INSERM 244, Biochimie des Régulations Cellulaires Endocrines, Département de Biologie Moléculaire et Structurale, CEA, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France.
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31
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Schneider GB, Gilmore AP, Lohse DL, Romer LH, Burridge K. Microinjection of protein tyrosine phosphatases into fibroblasts disrupts focal adhesions and stress fibers. CELL ADHESION AND COMMUNICATION 1998; 5:207-19. [PMID: 9686318 DOI: 10.3109/15419069809040292] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Microinjection and scrape-loading have been used to load cells in culture with soluble protein tyrosine phosphatases (PTPs). The introduction of protein tyrosine phosphatases into cells caused a rapid (within 5 minutes) decrease in tyrosine phosphorylation of major tyrosine phosphorylated substrates, including the focal adhesion kinase and paxillin. This decrease was detected both by blotting whole cell lysates with anti-phosphotyrosine antibodies and visualizing the phosphotyrosine in focal adhesions by immunofluorescence microscopy. After 30 minutes, many of the cells injected with tyrosine phosphatases revealed disruption of focal adhesions and stress fibers. To determine whether this disruption was due to the dephosphorylation of FAK and its substrates in focal adhesions, we have compared the effects of protein tyrosine phosphatase microinjection with the effects of displacing FAK from focal adhesions by microinjection of a dominant negative FAK construct. Although both procedures resulted in a marked decrease in the level of phosphotyrosine in focal adhesions, disruption of focal adhesions and stress fibers only occurred in cells loaded with exogenous protein tyrosine phosphatases. These results lead us to conclude that although tyrosine phosphorylation regulates focal adhesion and stress fiber stability, this does not involve FAK nor does it appear to involve tyrosine-phosphorylated proteins within focal adhesions. The critical tyrosine phosphorylation event is upstream of focal adhesions, a likely target being in the Rho pathway that regulates the formation of stress fibers and focal adhesions.
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Affiliation(s)
- G B Schneider
- Department of Prosthodontics, School of Dentistry, University of North Carolina, Chapel Hill 27599, USA.
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32
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Abstract
The integrins are a family of cell surface receptors which mediate cellular adhesion and signalling events. Our goal was to evaluate integrin function and signalling pathways in ovarian cancer cells. Ovarian cancer cell lines, NIH:OVCAR-3 and NIH:OVCAR-5, exhibited distinct extracellular matrix (ECM) binding preferences which were mediated primarily through beta1 integrin interactions. Western blot analysis was used to identify changes in cellular phosphotyrosine, focal adhesion kinase (FAK) and mitogen activated protein (MAP) kinase. Tyrosine phosphorylation of integrin-associated phosphoproteins was not enhanced in either cell type in response to adhesion onto ECM components or receptor crosslinking. FAK expression was greater in NIH:OVCAR-5 cells while MAP kinase activity was higher in NIH:OVCAR-3 cells. The data suggest that these two ovarian cancer cell lines exhibit specific ECM binding preferences and distinct differences in phosphotyrosine, focal adhesion and MAP kinase expression profiles.
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Affiliation(s)
- J A Buczek-Thomas
- Wellman Laboratories of Photomedicine, Massachusetts General Hospital, Boston 02114, USA
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33
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Schaphorst KL, Pavalko FM, Patterson CE, Garcia JG. Thrombin-mediated focal adhesion plaque reorganization in endothelium: role of protein phosphorylation. Am J Respir Cell Mol Biol 1997; 17:443-55. [PMID: 9376119 DOI: 10.1165/ajrcmb.17.4.2502] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Endothelial cell (EC) gap formation and barrier function are subject to dual regulation by (1) axial contractile forces, regulated by myosin light chain kinase activity, and (2) tethering forces, represented by cell-cell and cell-substratum adhesions. We examined whether focal adhesion plaque proteins (vinculin and talin) and focal adhesion kinase, p125FAK (FAK), represent target regulatory sites involved in thrombin-mediated EC barrier dysfunction. Histologically, thrombin produced dramatic rearrangement of EC actin, vinculin, and FAK in parallel with the evolution of gap formation and barrier dysfunction. Vinculin and talin were in vitro substrates for phosphorylation by EC PKC, a key effector enzyme involved in thrombin-induced EC barrier dysfunction. Although vinculin and talin were phosphorylated in situ under basal conditions in 32P-labeled EC, thrombin failed to alter the basal level of phosphorylation of these proteins. Phosphotyrosine immunoblotting showed that neither vinculin nor talin was significantly phosphorylated in situ on tyrosine residues in unstimulated ECs, and this was not further increased after thrombin. In contrast, both thrombin and the thrombin receptor-activating peptide (TRAP) produced an increase in FAK phosphotyrosine levels (corrected for immunoreactive FAK content) present in EC immunoprecipitates. Ionomycin, which produces EC barrier dysfunction in a myosin light chain kinase-independent manner, was used to increase intracellular Ca2+ and evaluate the Ca2+ sensitivity of this observation. In contrast to thrombin, ionomycin effected a dramatic decrease in the phosphotyrosine-to-immunoreactive FAK ratios, suggesting distinct effects of the two agents on FAK phosphorylation and function. These data indicate that modulation of cell tethering via phosphorylation of focal adhesion proteins is complex, agonist-specific, and may be a relevant mechanism of EC barrier dysfunction in permeability models that do not depend on an increase in myosin 20-kD regulatory light chain phosphorylation.
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Affiliation(s)
- K L Schaphorst
- Department of Pulmonary and Critical Care Medicine, Indiana University Medical Center, Indianapolis 46202, USA
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Lyman S, Gilmore A, Burridge K, Gidwitz S, White GC. Integrin-mediated activation of focal adhesion kinase is independent of focal adhesion formation or integrin activation. Studies with activated and inhibitory beta3 cytoplasmic domain mutants. J Biol Chem 1997; 272:22538-47. [PMID: 9278407 DOI: 10.1074/jbc.272.36.22538] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Integrin alphaIIbbeta3 functions as the fibrinogen receptor on platelets and mediates platelet aggregation and clot retraction. Among the events that occur during either "inside-out" or "outside-in" signaling through alphaIIbbeta3 is the phosphorylation of focal adhesion kinase (pp125(FAK)) and the association of pp125(FAK) with cytoskeletal components. To examine the role of pp125(FAK) in these integrin-mediated events, pp125(FAK) phosphorylation and association with the cytoskeleton was determined in cells expressing two mutant forms of alphaIIbbeta3: alphaIIbbeta3(D723A/E726A), a constitutively active integrin in which the putative binding site for pp125(FAK) is altered, and alphaIIbbeta3(F727A/K729E/F730A), in which the putative binding site for alpha-actinin is altered. Both mutants were expressed on the cell surface and were able to bind ligand, either spontaneously or upon activation. Whereas cells expressing alphaIIbbeta3(D723A/E726A) were able to form focal adhesions and stress fibers upon adherence to fibrinogen, cells expressing alphaIIbbeta3(F727A/K729E/F730A) adhere to fibrinogen, but had reduced focal adhesions and stress fibers. pp125(FAK) is recruited to focal adhesions in adherent cells expressing alphaIIbbeta3(D723A/E726A) and is phosphorylated in adherent cells or in cells in suspension in the presence of fibrinogen. In adherent cells expressing alphaIIbbeta3(F727A/K729E/F730A), pp125(FAK) was phosphorylated despite reduced formation of focal adhesions and stress fibers. We conclude that activation of pp125(FAK) can be dissociated from two important events in integrin signaling, the assembly of focal adhesions in adherent cells and integrin activation following ligand occupation.
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Affiliation(s)
- S Lyman
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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Defilippi P, Venturino M, Gulino D, Duperray A, Boquet P, Fiorentini C, Volpe G, Palmieri M, Silengo L, Tarone G. Dissection of pathways implicated in integrin-mediated actin cytoskeleton assembly. Involvement of protein kinase C, Rho GTPase, and tyrosine phosphorylation. J Biol Chem 1997; 272:21726-34. [PMID: 9268301 DOI: 10.1074/jbc.272.35.21726] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
A panel of antibodies to the alphaIIbbeta3 integrin was used to promote adhesion of Chinese hamster ovary cells transfected with the alphaIIbbeta3 fibrinogen receptor. While some alphaIIbbeta3 antibodies were not able to induce p125 focal adhesion kinase (p125FAK) tyrosine phosphorylation, all the antibodies equally support cell adhesion but not spreading and assembly of actin stress fibers. Absence of stress fibers was also obtained by plating on antibodies directed to the hamster beta1 integrin. In contrast, cells plated on matrix proteins spread organizing actin stress fibers. Treatment with phorbol esters phorbol 12-myristate 13-acetate (PMA) induced cells to spread on antibodies-coated dishes but not to organize actin in stress fibers. The combination of PMA and cytotoxic necrotizing factor 1 (CNF1), a specific Rho activator, induced cell spreading and organization of stress fibers. PMA or the combination of PMA and CNF1 also increases tyrosine phosphorylation of p125FAK in response to antibodies that were otherwise unable to trigger this response. These data show that: 1) matrix proteins and antibodies differ in their ability to induce integrin-dependent actin cytoskeleton organization (while matrix induced stress fibers formation, antibodies did not); 2) p125FAK tyrosine phosphorylation is insufficient per se to trigger actin stress fibers formation since antibodies that activate p125FAK tyrosine phosphorylation did not lead to actin stress fibers assembly; and 3) the inability of anti-integrin antibodies to trigger stress fibers organization is overcome by concomitant activation of the protein kinase C (PKC) and Rho pathways; PKC activation leads to cell spreading and Rho activation is required to organize actin stress fibers.
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Affiliation(s)
- P Defilippi
- Dipartimento di Genetica, Biologia e Chimica Medica, Universita' di Torino, 10126 Torino, Italy.
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Iwaki K, Ohashi K, Ikeda M, Tsujioka K, Kajiya F, Kurimoto M. Decrease in the amount of focal adhesion kinase (p125(FAK)) in interleukin-1beta-stimulated human umbilical vein endothelial cells by binding of human monocytic cell lines. J Biol Chem 1997; 272:20665-70. [PMID: 9252385 DOI: 10.1074/jbc.272.33.20665] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Monocytes in the blood circulation migrate across endothelial cell monolayers lining the blood vessels and infiltrate into the underlying tissues in inflammation. However, little is known about the mechanisms by which leukocytes migrate across the endothelial barrier after binding and what molecules participate in the process. Addition of the human monocytic cell line THP-1 to interleukin-1beta (IL-1beta)-stimulated human umbilical vein endothelial cells (HUVEC) induced a decrease in the amount of focal adhesion kinase (p125(FAK)) protein, a tyrosine kinase localized at focal contacts and essential for cell attachment to the extracellular matrix, whereas little change was observed in the amount of other molecules associated with cell adhesion such as vascular cell adhesion molecule-1, alpha-catenin, and talin. A maximum decrease in the amount of p125(FAK) was observed 15-30 min after addition of THP-1 cells to HUVEC, after which the level of p125(FAK) gradually recovered. A reduction in the density of actin stress fibers in IL-1beta-activated HUVEC was observed in parallel with the decrease in p125(FAK). The p125(FAK) decrease was partially inhibited by preventing THP-1 binding to HUVEC using a mixture of antibodies to adhesion molecules. We suggest that the decrease in p125(FAK) triggered by binding of monocytes in inflammation facilitates the transendothelial migration of the monocytes by altering the adhesiveness of endothelial cells to the extracellular matrix.
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Affiliation(s)
- K Iwaki
- Fujisaki Institute, Hayashibara Biochemical Laboratories, Inc., 675-1 Fujisaki, Okayama 702, Japan
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Lin CS, Chen Y, Huynh T, Kramer R. Identification of the human alpha6 integrin gene promoter. DNA Cell Biol 1997; 16:929-37. [PMID: 9303435 DOI: 10.1089/dna.1997.16.929] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The alpha6 integrin subunit couples with either the beta1 or the beta4 subunit to form a laminin receptor. alpha6 expression is cell-type-specific and generally is present at high levels in epithelial and endothelial cells. To study its gene regulation, we isolated a genomic clone containing the human alpha6 integrin gene promoter. It includes 3 kb of the upstream flanking region, the first exon (385 bp), and 9 kb of the first intron. The alpha6 promoter directs transcription initiation from a primary site 202 nucleotides from the translation initiation codon. Unlike most other integrin gene promoters, the alpha6 promoter has a TATA box (GATAAA), which is located 22 nucleotides upstream from the primary transcription initiation site. A 190-bp region upstream from the TATA box is highly rich (78%) in C and G nucleotides and contains several Sp1 and AP2 binding sequences. However, full promoter activity (in the presence of the SV40 enhancer) requires only 78 bp of this C/G-rich sequence upstream from the TATA box. Slightly upstream from the C/G-rich region are a steroid receptor binding homolog and an epithelial-cell-specific E-pal sequence. Another possible epithelial cell-specific binding sequence (Ker1) is found immediately downstream from the TATA box. Cell-type-specific activities of the promoter paralleled the alpha6 mRNA levels in four tested cell lines. In the presence of the SV40 enhancer, alpha6 promoter activity increased approximately four-fold in primary keratinocytes and in HT1080 fibrosarcoma cells and 30-fold in T47D breast carcinoma cells, but remained undetectable in K562 leukemia cells. Genomic analysis that compared alpha6-expressing with non-alpha6-expressing cells suggested that DNA methylation is not involved in the silencing of the alpha6 gene in alpha6-negative cells. DNase I footprint analysis confirmed the binding of Sp1 and AP2 to their cognate sequences. A nuclear extract of high-alpha6-expressing HBL-100 cells also produced significant binding to these sites, suggesting that the two transcription factors are probably involved in the positive regulation of the alpha6 promoter.
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Affiliation(s)
- C S Lin
- Department of Stomatology, University of California, San Francisco 94143-0512, USA
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Bellis SL, Perrotta JA, Curtis MS, Turner CE. Adhesion of fibroblasts to fibronectin stimulates both serine and tyrosine phosphorylation of paxillin. Biochem J 1997; 325 ( Pt 2):375-81. [PMID: 9230116 PMCID: PMC1218570 DOI: 10.1042/bj3250375] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Tyrosine phosphorylation of paxillin by the focal adhesion kinase (FAK) has been implicated as a signal transduction mechanism associated with cell adhesion and cytoskeletal reorganization. The potential role of serine phosphorylation of paxillin in these events has not been well characterized. In this study we have examined the phosphorylation profile of paxillin both in vitro and in vivo. By using glutathione S-transferase-paxillin fusion proteins in precipitation-kinase assays in vitro we observed that a fusion protein spanning amino acid residues 54-313 of paxillin, and containing a FAK-binding site, precipitated substantial serine kinase activity as well as FAK activity from a smooth-muscle lysate. Together these kinases phosphorylated paxillin on tyrosine residue 118, a site that has been identified previously as a target for FAK phosphorylation, and on serine residues 188 and/or 190. The binding site for the serine kinase, the identity of which is currently unknown, was further mapped to residues 168-191 of paxillin. To assess the physiological relevance of these sites phosphorylated in vitro, the profile of paxillin phosphorylation in vivo stimulated by seeding fibroblasts on fibronectin was characterized. As expected, plating cells on fibronectin enhanced the tyrosine phosphorylation of paxillin. However, 96% of the phosphorylation of paxillin occurred on serine residues. Comparison by two-dimensional phosphopeptide analyses indicated that the major sites of tyrosine and serine phosphorylation detected in the assays in vitro co-migrate with phosphopeptides derived from paxillin phosphorylated in vivo in response to plating cells on fibronectin. These findings support a role for both tyrosine and serine kinases in the signal transduction pathway linking integrin activation to paxillin phosphorylation.
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Affiliation(s)
- S L Bellis
- Department of Anatomy and Cell Biology, State University of New York Health Science Center, 750 E. Adams Street, Syracuse, NY 13210, USA
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Abstract
Focal adhesions are sites of tight adhesion to the underlying extracellular matrix developed by cells in culture. They provided a structural link between the actin cytoskeleton and the extracellular matrix and are regions of signal transduction that relate to growth control. The assembly of focal adhesions is regulated by the GTP-binding protein Rho. Rho stimulates contractility which, in cells that are tightly adherent to the substrate, generates isometric tension. In turn, this leads to the bundling of actin filaments and the aggregation of integrins (extracellular matrix receptors) in the plane of the membrane. The aggregation of integrins activates the focal adhesion kinase and leads to the assembly of a multicomponent signaling complex.
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Affiliation(s)
- K Burridge
- Department of Cell Biology and Anatomy, University of North Carolina at Chapel Hill 27599-7090, USA
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Abstract
Adhesive interactions play critical roles in directing the migration, proliferation, and differentiation of cells; aberrations in such interactions can lead to pathological disorders. These adhesive interactions, mediated by cell surface receptors that bind to ligands on adjacent cells or in the extracellular matrix, also regulate intracellular signal transduction pathways that control adhesion-induced changes in cell physiology. Though the extracellular molecular interactions involving many adhesion receptors have been well characterized, the adhesion-dependent intracellular signaling events that regulate these physiological alterations have only begun to be elucidated. This article will focus on recent advances in our understanding of intracellular signal transduction pathways regulated by the integrin family of adhesion receptors.
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Affiliation(s)
- E A Clark
- ARIAD Pharmaceuticals, Cambridge, MA 02139, USA
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Miyamoto S, Akiyama SK, Yamada KM. Synergistic roles for receptor occupancy and aggregation in integrin transmembrane function. Science 1995; 267:883-5. [PMID: 7846531 DOI: 10.1126/science.7846531] [Citation(s) in RCA: 683] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Integrin receptors mediate cell adhesion, signal transduction, and cytoskeletal organization. How a single transmembrane receptor can fulfill multiple functions was clarified by comparing roles of receptor occupancy and aggregation. Integrin occupancy by monovalent ligand induced receptor redistribution, but minimal tyrosine phosphorylation signaling or cytoskeletal protein redistribution. Aggregation of integrins by noninhibitory monoclonal antibodies on beads induced intracellular accumulations of pp125FAK and tensin, as well as phosphorylation, but no accumulation of other cytoskeletal proteins such as talin. Combining antibody-mediated clustering with monovalent ligand occupancy induced accumulation of seven cytoskeletal proteins, including alpha-actinin, talin, and F-actin, thereby mimicking multivalent interactions with fibronectin or polyvalent peptides. Integrins therefore mediate a complex repertoire of functions through the distinct effects of receptor aggregation, receptor occupancy, or both together.
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Affiliation(s)
- S Miyamoto
- Laboratory of Developmental Biology, National Institute of Dental Research, National Institutes of Health, Bethesda, MD 20892-4370
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Brooks PC, Montgomery AM, Rosenfeld M, Reisfeld RA, Hu T, Klier G, Cheresh DA. Integrin alpha v beta 3 antagonists promote tumor regression by inducing apoptosis of angiogenic blood vessels. Cell 1994; 79:1157-64. [PMID: 7528107 DOI: 10.1016/0092-8674(94)90007-8] [Citation(s) in RCA: 1672] [Impact Index Per Article: 55.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A single intravascular injection of a cyclic peptide or monoclonal antibody antagonist of integrin alpha v beta 3 disrupts ongoing angiogenesis on the chick chorioallantoic membrane (CAM). This leads to the rapid regression of histologically distinct human tumors transplanted onto the CAM. Induction of angiogenesis by a tumor or cytokine promotes vascular cell entry into the cell cycle and expression of integrin alpha v beta 3. After angiogenesis is initiated, antagonists of this integrin induce apoptosis of the proliferative angiogenic vascular cells, leaving preexisting quiescent blood vessels unaffected. We demonstrate therefore that ligation of integrin alpha v beta 3 is required for the survival and maturation of newly forming blood vessels, an event essential for the proliferation of tumors.
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Affiliation(s)
- P C Brooks
- Department of Immunology, Scripps Research Institute, La Jolla, California 92037
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Balzac F, Retta SF, Albini A, Melchiorri A, Koteliansky VE, Geuna M, Silengo L, Tarone G. Expression of beta 1B integrin isoform in CHO cells results in a dominant negative effect on cell adhesion and motility. J Cell Biol 1994; 127:557-65. [PMID: 7523423 PMCID: PMC2120206 DOI: 10.1083/jcb.127.2.557] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The integrin subunit beta 1B, a beta 1 isoform with a unique sequence at the cytoplasmic domain, forms heterodimers with integrin alpha chains and binds fibronectin, but it does not localize to focal adhesion sites (Balzac, F., A. Belkin, V. Koteliansky, Y. Balabanow, F. Altruda, L. Silengo, and G. Tarone. 1993. J. Cell Biol. 121:171-178). Here we analyze the functional properties of human beta 1B by expressing it in hamster CHO cells. When stimulated by specific antibodies, beta 1B does not trigger tyrosine phosphorylation of a 125-kD cytosolic protein, an intracellular signalling pathway that is activated both by the endogenous hamster or the transfected human beta 1A. Moreover, expression of beta 1B results in reduced spreading on fibronectin and laminin, but not on vitronectin. Expression of beta 1B also results in severe reduction of cell motility in the Boyden chamber assay. Reduced cell spreading and motility could not be accounted for by preferential association of beta 1B with a given integrin alpha subunit. These data, together with our previous results, indicate that beta 1B interferes with beta 1A function when expressed in CHO cells resulting in a dominant negative effect on cell adhesion and migration.
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Affiliation(s)
- F Balzac
- Department of Genetics, Biology and Medical Chemistry, University of Torino, Italy
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