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White ES, Muro AF. Fibronectin splice variants: understanding their multiple roles in health and disease using engineered mouse models. IUBMB Life 2012; 63:538-46. [PMID: 21698758 DOI: 10.1002/iub.493] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The extracellular matrix (ECM) is a highly dynamic network of proteins, glycoproteins, and proteoglycans. Numerous diseases result from mutation in genes coding for ECM proteins, but only recently it has been reported that mutations in the fibronectin (FN) gene were associated with a human disorder. FN is one of the main components of the ECM. It generates protein diversity through alternative splicing of a single pre-mRNA, having at least 20 different isoforms in humans. The precise function of these protein isoforms has remained obscure in most cases. Only in the recent few years, it was possible to shed light on the multiple roles of the alternatively spliced FN isoforms. This substantial progress was achieved basically with the knowledge derived from engineered mouse models bearing subtle mutations in specific FN domains. These data, together with a recent report associating mutations in the FN gene to a form of glomerulopathy, clearly show that mutations in constitutive exons or misregulation of alternatively spliced domains of the FN gene may have nonlethal pathological consequences. In this review, we focus on the pathological consequences of mutations in the FN gene, by connecting the function of alternatively spliced isoforms of fibronectin to human diseases.
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Affiliation(s)
- Eric S White
- Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
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102
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Larjava H, Koivisto L, Häkkinen L, Heino J. Epithelial integrins with special reference to oral epithelia. J Dent Res 2011; 90:1367-76. [PMID: 21441220 PMCID: PMC3215754 DOI: 10.1177/0022034511402207] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Revised: 02/07/2011] [Accepted: 02/07/2011] [Indexed: 01/15/2023] Open
Abstract
Adhesion of epithelium to the extracellular matrix is crucial for the maintenance of systemic and oral health. In the oral cavity, teeth or artificial dental implants penetrate the soft tissue of the gingiva. In this interface, gingival soft tissue needs to be well attached via the epithelial seal to the tooth or implant surface to maintain health. After injury or wounding, epithelial tissue rapidly migrates to form the initial epithelial cover to restore the barrier against infection. These events are crucially dependent on deposition of extracellular matrix and proper activation and function of integrin receptors in the epithelial cells. Recent experimental evidence suggests that epithelial integrins also participate in the regulation of periodontal inflammation. In this review, we will discuss the structure and function of epithelial integrins and their extracellular ligands and elaborate on their potential role in disease and repair processes in the oral cavity.
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Affiliation(s)
- H Larjava
- Laboratory of Periodontal Biology, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, BC, Canada.
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103
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Kawelke N, Vasel M, Sens C, von Au A, Dooley S, Nakchbandi IA. Fibronectin protects from excessive liver fibrosis by modulating the availability of and responsiveness of stellate cells to active TGF-β. PLoS One 2011; 6:e28181. [PMID: 22140539 PMCID: PMC3225392 DOI: 10.1371/journal.pone.0028181] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 11/02/2011] [Indexed: 12/22/2022] Open
Abstract
Fibrotic tissue in the liver is mainly composed of collagen. Fibronectin, which is also present in fibrotic matrices, is required for collagen matrix assembly in vitro. It also modulates the amount of growth factors and their release from the matrix. We therefore examined the effects of the absence of fibronectin on the development of fibrosis in mice. Conditional deletion of fibronectin in the liver using the Mx promoter to drive cre expression resulted in increased collagen production and hence a more pronounced fibrosis in response to dimethylnitrosamine in mice. Exclusive deletion of fibronectin in hepatocytes or normalization of circulating fibronectin in Mx-cKO mice did not affect the development of fibrosis suggesting a role for fibronectin production by other liver cell types. The boosted fibrosis in fibronectin-deficient mice was associated with enhanced stellate cell activation and proliferation, elevated concentrations of active TGF-β, and increased TGF-β-mediated signaling. In vitro experiments revealed that collagen-type-I production by fibronectin-deficient hepatic stellate cells stimulated with TGF-β was more pronounced, and was associated with augmented Smad3-mediated signaling. Interfering with TGF-β signaling using SB431542 normalized collagen-type-I production in fibronectin-deficient hepatic stellate cells. Furthermore, precoating culture plates with fibronectin, but not collagen, or providing fibronectin fibrils unable to interact with RGD binding integrins via the RGD domain significantly diminished the amount of active TGF-β in fibronectin-deficient stellate cells and normalized collagen-type-I production in response to TGF-β stimulation. Thus, excessive stellate cell activation and production of collagen results from increased active TGF-β and TGF-β signaling in the absence of fibronectin. In conclusion, our data indicate that fibronectin controls the availability of active TGF-β in the injured liver, which impacts the severity of the resulting fibrosis. We therefore propose a novel role for locally produced fibronectin in protecting the liver from an excessive TGF-β-mediated response.
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Affiliation(s)
- Nina Kawelke
- Translational Medicine, Max-Planck Institute for Biochemistry, Martinsried, Germany
- Institute for Immunology, University of Heidelberg, Heidelberg, Germany
| | - Matthaeus Vasel
- Translational Medicine, Max-Planck Institute for Biochemistry, Martinsried, Germany
- Institute for Immunology, University of Heidelberg, Heidelberg, Germany
| | - Carla Sens
- Translational Medicine, Max-Planck Institute for Biochemistry, Martinsried, Germany
- Institute for Immunology, University of Heidelberg, Heidelberg, Germany
| | - Anja von Au
- Translational Medicine, Max-Planck Institute for Biochemistry, Martinsried, Germany
- Institute for Immunology, University of Heidelberg, Heidelberg, Germany
| | - Steven Dooley
- Department of Medicine II, University of Heidelberg at Mannheim, Mannheim, Germany
| | - Inaam A. Nakchbandi
- Translational Medicine, Max-Planck Institute for Biochemistry, Martinsried, Germany
- Institute for Immunology, University of Heidelberg, Heidelberg, Germany
- * E-mail:
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104
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Deng Z, Cheng Z, Xiang X, Yan J, Zhuang X, Liu C, Jiang H, Ju S, Zhang L, Grizzle W, Mobley J, Roman J, Miller D, Zhang HG. Tumor cell cross talk with tumor-associated leukocytes leads to induction of tumor exosomal fibronectin and promotes tumor progression. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 180:390-8. [PMID: 22067905 DOI: 10.1016/j.ajpath.2011.09.023] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 09/08/2011] [Accepted: 09/27/2011] [Indexed: 01/05/2023]
Abstract
Exosomes participate in intercellular communication, but most data published are based on exosomes released from in vitro cultured cells that do not communicate with neighboring cells located in the same microenvironment as the exosomal-producing cells in vivo. In this study, our data show that co-culture of leukocytes isolated from breast tumor tissue leads to uptake of fibronectin (FN) on or in the tumor exosomes (Exo(fib+)). The induction of FN and exosomal uptake is tumor tissue derived and leukocyte specific, because leukocytes isolated from the peripheral blood of naïve mice failed to induce FN uptake by tumor exosomes. Furthermore, depletion of both CD25(+) cells and Gr-1(+) cells from tumor-associated leukocytes causes a reduction of Exo(fib+), suggesting that tumor-associated CD25(+) cells and Gr-1(+) cells participate in FN production and uptake by tumor exosomes, resulting in Exo(fib+). As a result of tumor cells absorbing Exo(fib+), two major events are induced: focal adhesion kinase/Src-dependent signaling pathways are activated, and the production of proinflammatory cytokines and metalloproteinase 9 is enhanced in response to absorbing exosomes. This, in turn, enhances tumor cell invasion in vitro and in vivo. Collectively, our findings provide evidence that exosomes released from freshly excised tumor tissue cells that have communicated/interacted with immune cells gain new immune evasion capacity.
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Affiliation(s)
- ZhongBin Deng
- Department of Research & Development, Robley Rex Medical Center, Louisville, Kentucky, USA
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105
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Danussi C, Petrucco A, Wassermann B, Pivetta E, Modica TME, Del Bel Belluz L, Colombatti A, Spessotto P. EMILIN1-α4/α9 integrin interaction inhibits dermal fibroblast and keratinocyte proliferation. ACTA ACUST UNITED AC 2011; 195:131-45. [PMID: 21949412 PMCID: PMC3187715 DOI: 10.1083/jcb.201008013] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The α4/α9 integrins directly engage the ECM glycoprotein EMILIN1 to inhibit skin cell proliferation upstream of TGF-β signaling. EMILIN1 promotes α4β1 integrin–dependent cell adhesion and migration and reduces pro–transforming growth factor–β processing. A knockout mouse model was used to unravel EMILIN1 functions in skin where the protein was abundantly expressed in the dermal stroma and where EMILIN1-positive fibrils reached the basal keratinocyte layer. Loss of EMILIN1 caused dermal and epidermal hyperproliferation and accelerated wound closure. We identified the direct engagement of EMILIN1 to α4β1 and α9β1 integrins as the mechanism underlying the homeostatic role exerted by EMILIN1. The lack of EMILIN1–α4/α9 integrin interaction was accompanied by activation of PI3K/Akt and Erk1/2 pathways as a result of the reduction of PTEN. The down-regulation of PTEN empowered Erk1/2 phosphorylation that in turn inhibited Smad2 signaling by phosphorylation of residues Ser245/250/255. These results highlight the important regulatory role of an extracellular matrix component in skin proliferation. In addition, EMILIN1 is identified as a novel ligand for keratinocyte α9β1 integrin, suggesting prospective roles for this receptor–ligand pair in skin homeostasis.
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Affiliation(s)
- Carla Danussi
- Division of Experimental Oncology 2, Centro di Riferimento Oncologico, Istituto di Ricovero e Cura a Carattere Scientifico, National Cancer Institute, 33081 Aviano, Italy
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106
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To WS, Midwood KS. Plasma and cellular fibronectin: distinct and independent functions during tissue repair. FIBROGENESIS & TISSUE REPAIR 2011; 4:21. [PMID: 21923916 PMCID: PMC3182887 DOI: 10.1186/1755-1536-4-21] [Citation(s) in RCA: 385] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Accepted: 09/16/2011] [Indexed: 01/01/2023]
Abstract
Fibronectin (FN) is a ubiquitous extracellular matrix (ECM) glycoprotein that plays vital roles during tissue repair. The plasma form of FN circulates in the blood, and upon tissue injury, is incorporated into fibrin clots to exert effects on platelet function and to mediate hemostasis. Cellular FN is then synthesized and assembled by cells as they migrate into the clot to reconstitute damaged tissue. The assembly of FN into a complex three-dimensional matrix during physiological repair plays a key role not only as a structural scaffold, but also as a regulator of cell function during this stage of tissue repair. FN fibrillogenesis is a complex, stepwise process that is strictly regulated by a multitude of factors. During fibrosis, there is excessive deposition of ECM, of which FN is one of the major components. Aberrant FN-matrix assembly is a major contributing factor to the switch from normal tissue repair to misregulated fibrosis. Understanding the mechanisms involved in FN assembly and how these interplay with cellular, fibrotic and immune responses may reveal targets for the future development of therapies to regulate aberrant tissue-repair processes.
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Affiliation(s)
- Wing S To
- Department of Matrix Biology, Kennedy Institute of Rheumatology Division, Nuffield Department of Orthopedic Rheumatology and Musculoskeletal Sciences, Oxford University, 65 Aspenlea Road, London, W6 8LH, UK.
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107
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Abstract
Integrin-mediated cell adhesion is involved in many essential normal cellular and pathological functions including cell survival, growth, differentiation, migration, inflammatory responses, platelet aggregation, tissue repair and tumor invasion. 24 different heterodimerized transmembrane integrin receptors are combined from 18 different α and 8 different β subunits. Each integrin subunit contains a large extracellular domain, a single transmembrane domain and a usually short cytoplasmic domain. Integrins bind extracellular matrix (ECM) proteins through their large extracellular domain, and engage the cytoskeleton via their short cytoplasmic tails. These integrin-mediated linkages on either side of the plasma membrane are dynamically linked. Thus, integrins communicate over the plasma membrane in both directions, i.e., outside-in and inside-out signaling. In outside-in signaling through integrins, conformational changes of integrin induced by ligand binding on the extracellular domain altered the cytoplasmic domain structures to elicit various intracellular signaling pathways. Inside-out signaling originates from non-integrin cell surface receptors or cytoplasmic molecules and it activates signaling pathways inside the cells, ultimately resulting in the activation/deactivation of integrins. Integrins are one of key family proteins for cell adhesion regulation through binding to a large number of ECM molecules and cell membrane proteins. Lack of expression of integrins may result in a wide variety of effects ranging from blockage in pre-implantation to embryonic or perinatal lethality and developmental defects. Based on both the key role they played in angiogenesis, leukocytes function and tumor development and easy accessibility as cell surface receptors interacting with extracellular ligands, the integrin superfamily represents the best opportunity of targeting both antibodies and small-molecule antagonists for both therapeutic and diagnostic utility in various key diseases so far.
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108
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Schwarzbauer JE, DeSimone DW. Fibronectins, their fibrillogenesis, and in vivo functions. Cold Spring Harb Perspect Biol 2011; 3:cshperspect.a005041. [PMID: 21576254 DOI: 10.1101/cshperspect.a005041] [Citation(s) in RCA: 289] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Fibronectin (FN) is a multidomain protein with the ability to bind simultaneously to cell surface receptors, collagen, proteoglycans, and other FN molecules. Many of these domains and interactions are also involved in the assembly of FN dimers into a multimeric fibrillar matrix. When, where, and how FN binds to its various partners must be controlled and coordinated during fibrillogenesis. Steps in the process of FN fibrillogenesis including FN self-association, receptor activities, and intracellular pathways have been under intense investigation for years. In this review, the domain organization of FN including the extra domains and variable region that are controlled by alternative splicing are described. We discuss how FN-FN and cell-FN interactions play essential roles in the initiation and progression of matrix assembly using complementary results from cell culture and embryonic model systems that have enhanced our understanding of this process.
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Affiliation(s)
- Jean E Schwarzbauer
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, USA.
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109
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Bielefeld KA, Amini-Nik S, Whetstone H, Poon R, Youn A, Wang J, Alman BA. Fibronectin and beta-catenin act in a regulatory loop in dermal fibroblasts to modulate cutaneous healing. J Biol Chem 2011; 286:27687-97. [PMID: 21652705 DOI: 10.1074/jbc.m111.261677] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
β-Catenin is an important regulator of dermal fibroblasts during cutaneous wound repair. However, the factors that modulate β-catenin activity in this process are not completely understood. We investigated the role of the extracellular matrix in regulating β-catenin and found an increase in β-catenin-mediated Tcf-dependent transcriptional activity in fibroblasts exposed to various extracellular matrix components. This occurs through an integrin-mediated GSK3β-dependent pathway. The physiologic role of this mechanism was demonstrated during wound repair in extra domain A-fibronectin-deficient mice, which exhibited decreased β-catenin-mediated signaling during the proliferative phase of healing. Extra domain A-fibronectin-deficient mice have wounds that fail at a lower tensile strength and contain fewer fibroblasts compared with wild type mice. This phenotype was rescued by genetic or pharmacologic activation of β-catenin signaling. Because fibronectin is a transcriptional target of β-catenin, this suggests the existence of a feedback loop between these two molecules that regulates dermal fibroblast cell behavior during wound repair.
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Affiliation(s)
- Kirsten A Bielefeld
- Program in Developmental and Stem Cell Biology, Hospital for Sick Children Research Institute, Toronto, Ontario M5G 1L7, Canada
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110
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Peters JH, Grote MN, Lane NE, Maunder RJ. Changes in plasma fibronectin isoform levels predict distinct clinical outcomes in critically ill patients. Biomark Insights 2011; 6:59-68. [PMID: 21695089 PMCID: PMC3115635 DOI: 10.4137/bmi.s7204] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
INTRODUCTION Concentrations of the total pool of fibronectin in plasma (TFN), and the subset of this pool that contains the alternatively spliced EDA segment (A(+)FN), are both affected by disease processes, and the latter pool has gained a reputation as a biomarker for vascular injury. We therefore wished to determine if changes in either FN pool correlate with clinical outcomes in critically ill individuals. METHODS We analyzed a database for 57 patients with major trauma (n = 33) or sepsis syndrome (n = 24) in which plasma levels of TFN and A(+)FN had been measured at intervals, along with clinical parameters. Logistic regression analysis was performed to detect associations between predictive variables and three clinical outcomes: 1) the acute respiratory distress syndrome (ARDS), 2) milder acute lung injury designated acute hypoxemic respiratory failure (AHRF), and 3) survival to hospital discharge. RESULTS An increase in plasma TFN during the first 24 hours of intensive care unit (ICU) observation was negatively associated with progression to ARDS (odds ratio 0.98 per 1 microgram (μg)/ml increase, 95% CI (0.97, 1.00)) and AHRF (OR 0.97 per 1 μg/ml increase, (0.95, 0.99)), whereas an increase in A(+)FN over the first 24 hours was positively associated with progression to AHRF (OR 1.65 per 1 μg/ml increase, (1.04, 2.62)). Additionally, the ratio of the partial pressure of oxygen in arterial blood (PaO(2)) to the percentage of oxygen in inspired air (FIO(2)) after 24 hours was positively associated with survival (OR 1.01 per 1 unit increase in ratio, (1.00, 1.03)), along with change in A(+)FN (OR 1.30 per 1 μg/ml increase, (0.90, 1.88)). CONCLUSIONS Different FN isoforms may constitute predictive covariate markers for distinct clinical outcomes in critically ill patients. The data also suggest that early TFN accumulation in the circulation may confer a clinical benefit to patients at risk for acute lung injury.
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Affiliation(s)
- John H Peters
- Department of Medicine, Sacramento Medical Center, VA Northern California Health Care System, Mather, CA 95655
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111
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Abstract
Despite advances in treatment of patients who suffer from ischemic heart disease, morbidity related to myocardial infarction is increasing in Western societies. Acute and chronic immune responses elicited by myocardial ischemia have an important role in the functional deterioration of the heart. Research on modulation of the inflammatory responses was focused on effector mediators such as leukocytes. However, increasing evidence indicates that various endogenous ligands that act as 'danger signals', also called danger-associated molecular patterns (DAMPs), are released upon injury and modulate inflammation. Originally described as part of the first-line defense against invading microorganisms, several Toll-like receptors (TLRs) on leukocytes and parenchymal cells have now been shown to respond to such signals and to have a pivotal role in noninfectious pathological cardiovascular conditions, such as ischemia-reperfusion injury and heart failure. From a therapeutic perspective, DAMPs are attractive targets owing to their specific induction after injury. In this Review, we will discuss innate immune activation through TLRs in cardiac ischemia mediated by DAMPs.
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Affiliation(s)
- Fatih Arslan
- University Medical Center Utrecht, Laboratory of Experimental Cardiology, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
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112
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Barnes RM, Firulli BA, VanDusen NJ, Morikawa Y, Conway SJ, Cserjesi P, Vincentz JW, Firulli AB. Hand2 loss-of-function in Hand1-expressing cells reveals distinct roles in epicardial and coronary vessel development. Circ Res 2011; 108:940-9. [PMID: 21350214 DOI: 10.1161/circresaha.110.233171] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
RATIONALE The basic helix-loop-helix (bHLH) transcription factors Hand1 and Hand2 are essential for embryonic development. Given their requirement for cardiogenesis, it is imperative to determine their impact on cardiovascular function. OBJECTIVE To deduce the role of Hand2 within the epicardium. METHOD AND RESULTS We engineered a Hand1 allele expressing Cre recombinase. Cardiac Hand1 expression is largely limited to cells of the primary heart field, overlapping little with Hand2 expression. Hand1 is expressed within the septum transversum, and the Hand1 lineage marks the proepicardial organ and epicardium. To examine Hand factor functional overlap, we conditionally deleted Hand2 from Hand1-expressing cells. Hand2 mutants display defective epicardialization and fail to form coronary arteries, coincident with altered extracellular matrix deposition and Pdgfr expression. CONCLUSIONS These data demonstrate a hierarchal relationship whereby transient Hand1 septum transversum expression defines epicardial precursors that are subsequently dependent on Hand2 function.
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Affiliation(s)
- Ralston M Barnes
- Riley Heart Research Center, Wells Center for Pediatric Research, Division of Pediatric Cardiology, Departments of Anatomy and Medical and Molecular Genetics, Indiana Medical School, Indianapolis, 46202-5225, USA
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113
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Arslan F, Smeets MB, Riem Vis PW, Karper JC, Quax PH, Bongartz LG, Peters JH, Hoefer IE, Doevendans PA, Pasterkamp G, de Kleijn DP. Lack of fibronectin-EDA promotes survival and prevents adverse remodeling and heart function deterioration after myocardial infarction. Circ Res 2011; 108:582-92. [PMID: 21350212 DOI: 10.1161/circresaha.110.224428] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE The extracellular matrix may induce detrimental inflammatory responses on degradation, causing adverse cardiac remodeling and heart failure. The extracellular matrix protein fibronectin-EDA (EIIIA; EDA) is upregulated after tissue injury and may act as a "danger signal" for leukocytes to cause adverse cardiac remodeling after infarction. OBJECTIVE In the present study, we evaluated the role of EDA in regulation of postinfarct inflammation and repair after myocardial infarction. METHODS AND RESULTS Wild-type and EDA(-/-) mice underwent permanent ligation of the left anterior coronary artery. Despite equal infarct size between groups (38.2±4.6% versus 38.2±2.9% of left ventricle; P=0.985), EDA(-/-) mice exhibited less left ventricular dilatation and enhanced systolic performance compared with wild-type mice as assessed by serial cardiac MRI measurements. In addition, EDA(-/-) mice exhibited reduced fibrosis of the remote area without affecting collagen production, cross-linking, and deposition in the infarct area. Subsequently, ventricular contractility and relaxation was preserved in EDA(-/-). At tissue level, EDA(-/-) mice showed reduced inflammation, metalloproteinase 2 and 9 activity, and myofibroblast transdifferentiation. Bone marrow transplantation experiments revealed that myocardium-induced EDA and not EDA from circulating cells regulates postinfarct remodeling. Finally, the absence of EDA reduced monocyte recruitment as well as monocytic Toll-like receptor 2 and CD49d expression after infarction. CONCLUSIONS Our study demonstrated that parenchymal fn-EDA plays a critical role in adverse cardiac remodeling after infarction. Absence of fn-EDA enhances survival and cardiac performance by modulating matrix turnover and inflammation via leukocytes and fibroblasts after infarction.
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Affiliation(s)
- Fatih Arslan
- Laboratory of Experimental Cardiology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
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114
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Cseh B, Fernandez-Sauze S, Grall D, Schaub S, Doma E, Van Obberghen-Schilling E. Autocrine fibronectin directs matrix assembly and crosstalk between cell–matrix and cell–cell adhesion in vascular endothelial cells. J Cell Sci 2010; 123:3989-99. [DOI: 10.1242/jcs.073346] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Cellular fibronectin (cFN) variants harboring extra FN type 3 repeats, namely extra domains B and A, are major constituents of the extracellular matrix around newly forming blood vessels during development and angiogenesis. Their expression is induced by angiogenic stimuli and their assembly into fibrillar arrays is driven by cell-generated tension at α5β1 integrin-based adhesions. Here, we examined the role and functional redundancy of cFN variants in cultured endothelial cells by isoform-selective RNA interference. We show that FN fibrillogenesis is a cell-autonomous process whereby basally directed secretion and assembly of cellular FN are tightly coupled events that play an important role not only in signaling at cell–matrix adhesions but also at cell–cell contacts. Silencing of cFN variants differentially affects integrin usage, cell spreading, motility and capillary morphogenesis in vitro. cFN-deficient cells undergo a switch from α5β1- to αvβ3-based adhesion, accompanied by a Src-regulated disruption of adherens junctions. These studies identify a crucial role for autocrine FN in subendothelial matrix assembly and junctional integrity that provides spatially and temporally restricted control of endothelial plasticity during angiogenic blood vessel remodeling.
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Affiliation(s)
- Botond Cseh
- University of Nice-Sophia Antipolis, CNRS UMR 6543, Centre Antoine Lacassagne, 33 Avenue de Valombrose, 06189 Nice, France
| | - Samantha Fernandez-Sauze
- University of Nice-Sophia Antipolis, CNRS UMR 6543, Centre Antoine Lacassagne, 33 Avenue de Valombrose, 06189 Nice, France
| | - Dominique Grall
- University of Nice-Sophia Antipolis, CNRS UMR 6543, Centre Antoine Lacassagne, 33 Avenue de Valombrose, 06189 Nice, France
| | - Sébastien Schaub
- University of Nice-Sophia Antipolis, CNRS UMR 6543, Centre Antoine Lacassagne, 33 Avenue de Valombrose, 06189 Nice, France
| | - Eszter Doma
- University of Nice-Sophia Antipolis, CNRS UMR 6543, Centre Antoine Lacassagne, 33 Avenue de Valombrose, 06189 Nice, France
| | - Ellen Van Obberghen-Schilling
- University of Nice-Sophia Antipolis, CNRS UMR 6543, Centre Antoine Lacassagne, 33 Avenue de Valombrose, 06189 Nice, France
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115
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Wiig H, Keskin D, Kalluri R. Interaction between the extracellular matrix and lymphatics: consequences for lymphangiogenesis and lymphatic function. Matrix Biol 2010; 29:645-56. [PMID: 20727409 PMCID: PMC3992865 DOI: 10.1016/j.matbio.2010.08.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Revised: 08/03/2010] [Accepted: 08/03/2010] [Indexed: 12/19/2022]
Abstract
The lymphatic system is important for body fluid balance as well as immunological surveillance. Due to the identification of new molecular markers during the last decade, there has been a recent dramatic increase in our knowledge on the molecular mechanisms involved in lymphatic vessel growth (lymphangiogenesis) and lymphatic function. Here we review data showing that although it is often overlooked, the extracellular matrix plays an important role in the generation of new lymphatic vessels as a response to physiological and pathological stimuli. Extracellular matrix-lymphatic interactions as well as biophysical characteristics of the stroma have consequences for tumor formation, growth and metastasis. During the recent years, anti-lymphangiogenesis has emerged as an additional therapeutic modality to the clinically applied anti-angiogenesis strategy. Oppositely, enhancement of lymphangiogenesis in situations of lymph accumulation is seen as a promising strategy to a set of conditions where few therapeutic avenues are available. Knowledge on the interaction between the extracellular matrix and the lymphatics may enhance our understanding of the underlying mechanisms and may ultimately lead to better therapies for conditions where reduced or increased lymphatic function is the therapeutic target.
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Affiliation(s)
- Helge Wiig
- Division of Matrix Biology, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, United States
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116
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Carey WA, Taylor GD, Dean WB, Bristow JD. Tenascin-C deficiency attenuates TGF-ß-mediated fibrosis following murine lung injury. Am J Physiol Lung Cell Mol Physiol 2010; 299:L785-93. [PMID: 20833777 DOI: 10.1152/ajplung.00385.2009] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Tenascin-C (TNC) is an extracellular matrix glycoprotein of unknown function that is highly expressed in adult lung parenchyma following acute lung injury (ALI). Here we report that mice lacking TNC are protected from interstitial fibrosis in the bleomycin model of ALI. Three weeks after exposure to bleomycin, TNC-null mice had accumulated 85% less lung collagen than wild-type mice. The lung interstitium of TNC-null mice also appeared to contain fewer myofibroblasts and fewer cells with intranuclear Smad-2/3 staining, suggesting impaired TGF-β activation or signaling. In vitro, TNC-null lung fibroblasts exposed to constitutively active TGF-β expressed less α-smooth muscle actin and deposited less collagen I into the matrix than wild-type cells. Impaired TGF-β responsiveness was correlated with dramatically reduced Smad-3 protein levels and diminished nuclear translocation of Smad-2 and Smad-3 in TGF-β-exposed TNC-null cells. Reduced Smad-3 in TNC-null cells reflects both decreased transcript abundance and enhanced ubiquitin-proteasome-mediated protein degradation. Together, these studies suggest that TNC is essential for maximal TGF-β action after ALI. The clearance of TNC that normally follows ALI may restrain TGF-β action during lung healing, whereas prolonged or exaggerated TNC expression may facilitate TGF-β action and fibrosis after ALI.
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Affiliation(s)
- William A Carey
- Cardiovascular Research Institute, University of California, San Francisco, USA.
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117
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Kohan M, Muro AF, White ES, Berkman N. EDA-containing cellular fibronectin induces fibroblast differentiation through binding to alpha4beta7 integrin receptor and MAPK/Erk 1/2-dependent signaling. FASEB J 2010; 24:4503-12. [PMID: 20643910 DOI: 10.1096/fj.10-154435] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Fibroblast differentiation is an essential step during wound healing and fibrosis. Fibronectin (FN) is a major component of the extracellular matrix and occurs in two main forms: plasma and cellular FN. The latter includes the alternatively spliced domain A (EDA). Although EDA-containing cellular fibronectin (EDA-FN) is associated with fibroblast differentiation, how EDA-FN promotes differentiation is incompletely understood. In this study, we investigate the mechanism by which EDA-FN contributes to fibroblast differentiation with emphasis on the characterization of the EDA-FN receptor. We show that EDA-FN increases α-SMA expression (immunofluorescence), collagen deposition, cell contractility, and focal adhesion kinase (FAK) activation (immunoblotting); whereas plasma FN, a form lacking EDA, shows no effect. Primary lung fibroblasts constitutively express α(4)β(7) integrin receptor (FACS and RT-PCR). Blocking of α(4)β(7) reduces fibroblast adhesion to EDA-FN and inhibits α-SMA expression, collagen deposition, and FAK activation induced by EDA-FN. Using recombinant EDA-containing peptides, we demonstrate that the EDA segment is sufficient to induce fibroblast differentiation via binding to α(4)β(7). EDA-FN induces MAPK-Erk1/2 activation and inhibition of MEK1/2 attenuates EDA-FN-induced α-SMA expression. Our findings demonstrate that EDA-FN induces fibroblast differentiation by a mechanism that involves binding of EDA to α(4)β(7) integrin followed by activation of FAK and MAPK-associated signaling pathways.
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Affiliation(s)
- Martin Kohan
- Institute of Pulmonology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
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118
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Nakayama Y, Kon S, Kurotaki D, Morimoto J, Matsui Y, Uede T. Blockade of interaction of alpha9 integrin with its ligands hinders the formation of granulation in cutaneous wound healing. J Transl Med 2010; 90:881-94. [PMID: 20308983 DOI: 10.1038/labinvest.2010.69] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The wound healing is a complex process consisting of inflammatory reaction, proliferation of mesenchymal cells, and formation and contraction of granulation tissue. The integrin receptors have crucial roles in this process. Recently, alpha9 integrin has also been detected on keratinocytes within wound sites. However, its functional significance at various wound healing processes was not fully elucidated. To address the role of alpha9 integrin in wound healing process, we made a full-thickness skin excisional wound and treated mice with anti-alpha9 integrin antibody. It has been shown that wound healing process was divided into three distinct phases: first, the re-epithelialization phase, second, the phase of granulation tissue formation, and finally the phase of contraction of granulation tissue. We found that contraction of granulation tissue was not impaired by blocking the interaction of alpha9 integrin with its ligands, indicating that alpha9 integrin is not involved in myofibroblast differentiation. It is noteworthy that the formation of granulation tissue, as characterized by dense vimentin and CD31-positive area, was impaired. The hindrance of granulation tissue formation is because of the inhibition of adhesion and migration of alpha9 integrin-positive dermal fibroblasts. In conclusion, alpha9 integrin is involved in the formation of granulation tissue through regulating migration and adhesion of dermal fibroblasts in the full-thickness skin excisional wound model.
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Affiliation(s)
- Yosuke Nakayama
- Division of Molecular Immunology, Institute for Genetic Medicine, Hokkaido University, Kita-ku, Sapporo, Japan
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119
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Zhou Y, Hagood JS, Lu B, Merryman WD, Murphy-Ullrich JE. Thy-1-integrin alphav beta5 interactions inhibit lung fibroblast contraction-induced latent transforming growth factor-beta1 activation and myofibroblast differentiation. J Biol Chem 2010; 285:22382-93. [PMID: 20463011 DOI: 10.1074/jbc.m110.126227] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Myofibroblasts, key effector cells in tissue fibrosis, are specialized contractile cells. Lung myofibroblast contraction induces integrin alpha(v)beta(5)-dependent latent transforming growth factor (TGF)-beta1 activation suggests that myofibroblast contractility may be a driving force for the persistent myofibroblast differentiation observed in fibrotic lungs. Understanding the mechanisms that regulate fibroblast contraction and mechanotransduction will add new insights into the pathogenesis of lung fibrosis and may lead to new therapeutic approaches for treating fibrotic lung diseases. We and others previously demonstrated that lung fibroblast expression of Thy-1 prevents lung fibrosis. The mechanisms underlying the anti-fibrotic effect of Thy-1 are not well understood. In this study, we showed that Thy-1 interacts with integrin alpha(v)beta(5), both in a cell-free system and on the cell surface of rat lung fibroblasts. Thy-1-integrin alpha(v)beta(5) interactions are RLD-dependent because mutated Thy-1, in which RLD is replaced by RLE, loses the ability to bind the integrin. Furthermore, Thy-1 expression prevents fibroblast contraction-induced, integrin alpha(v)beta(5)-dependent latent TGF-beta1 activation and TGF-beta1-dependent lung myofibroblast differentiation. In contrast, lack of Thy-1 expression or disruption of Thy-1-alpha(v)beta(5) interactions renders lung fibroblasts susceptible to contraction-induced latent TGF-beta1 activation and myofibroblast differentiation. These data suggest that Thy-1-integrin alpha(v)beta(5) interactions inhibit contraction-induced latent TGF-beta1 activation, presumably by blocking the binding of extracellular matrix-bound latent TGF-beta1 with integrin alpha(v)beta(5). Our studies suggest that targeting key mechanotransducers to inhibit mechanotransduction might be an effective approach to inhibit the deleterious effects of myofibroblast contraction on lung fibrogenesis.
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Affiliation(s)
- Yong Zhou
- Department of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
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120
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Schwinn MK, Gonzalez JM, Gabelt BT, Sheibani N, Kaufman PL, Peters DM. Heparin II domain of fibronectin mediates contractility through an alpha4beta1 co-signaling pathway. Exp Cell Res 2010; 316:1500-12. [PMID: 20302860 DOI: 10.1016/j.yexcr.2010.03.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Revised: 02/26/2010] [Accepted: 03/10/2010] [Indexed: 01/12/2023]
Abstract
In the trabecular meshwork (TM) of the eye, regulation of tissue contractility by the PPRARI sequence within the Heparin II (HepII) domain of fibronectin is believed to control the movement of aqueous humor and dictate the level of intraocular pressure. This study shows that the HepII domain utilizes activated alpha4beta1 integrin and collagen to mediate a co-signaling pathway that down-regulates contractility in TM cells. siRNA silencing of alpha4beta1 integrin blocked the actin disrupting effects of both PPRARI and the HepII domain. The down-regulation of the actin cytoskeleton and contractility did not involve syndecan-4 or other heparan sulfate proteoglycans (HSPGs) since siRNA silencing of syndecan-4 expression or heparitinase removal of cell surface HSPGs did not prevent the HepII-mediated disruption of the actin cytoskeleton. HepII-mediated disruption of the cytoskeleton depended upon the presence of collagen in the extracellular matrix, and cell binding studies indicated that HepII signaling involved cross-talk between alpha4beta1 and alpha1/alpha2beta1 integrins. This is the first time that the PPRARI sequence in the HepII domain has been shown to serve as a physiological alpha4beta1 ligand, suggesting that alpha4beta1 integrin may be a key regulator of tissue contractility.
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Affiliation(s)
- Marie K Schwinn
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53706, USA
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121
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Fernandez C, Jami S, Loredo G, Ko F, Hahn T, McDougall S, Peters JH. Recognition of the alternatively spliced segments of fibronectin by the RCJ 3.1C5.18 chondrocytic rat cell line. Osteoarthritis Cartilage 2010; 18:228-39. [PMID: 19822234 DOI: 10.1016/j.joca.2009.09.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Revised: 08/24/2009] [Accepted: 09/09/2009] [Indexed: 02/02/2023]
Abstract
OBJECTIVES To define, for the C5.18 chondrocyte-restricted rat cell line, (1) the capacities for recognition of alternatively spliced segments of the adhesion protein fibronectin (FN), (2) the integrin subunits required for such recognition, and (3) differences in such FN recognition vs the multipotential chondroprogenitor line, RCJ 3.1. METHODS C5.18 and RCJ 3.1 cells were tested for their capacities to adhere to recombinant alternatively spliced segments of rat FN, presented on plastic surfaces either in isolation or in partial FNs spanning the 7th through 15th type III repeats (III7-15 FNs). The effects on such adhesion of cations and integrin subunit-specific antibodies were tested. RESULTS Despite significant augmentation in chondrocyte-specific gene expression in C5.18 relative to the RCJ 3.1 cells, the two lines exhibited similar recognition of FN spliced segments and partial isoforms. Specifically, both lines adhered to the extra type III repeat A (EIIIA) and V, but not extra type III repeat B (EIIIB), segments. There were different cation and integrin subunit requirements for adhesion to EIIIA vs V segments, and only the V segment was recognized in the context of a III7-15 FN. Such recognition was mediated via a "second" arginine-glycine-aspartic acid (RGD) sequence that is present in the V95 subsegment in rat, but not human, FN. CONCLUSION The chondrocyte lineage-committed C5.18 cell line, similar to its multipotential chondroprogenitor, RCJ 3.1, recognizes the "cartilage-restricted" EIIIA and V segments of FN with cation, integrin, and molecular context requirements that are specific to each of these segments.
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Affiliation(s)
- C Fernandez
- Center for Healthy Aging, Department of Internal Medicine, UC Davis School of Medicine, Sacramento, CA 95817, USA
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122
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Bazigou E, Xie S, Chen C, Weston A, Miura N, Sorokin L, Adams R, Muro AF, Sheppard D, Makinen T. Integrin-alpha9 is required for fibronectin matrix assembly during lymphatic valve morphogenesis. Dev Cell 2009; 17:175-86. [PMID: 19686679 PMCID: PMC2747264 DOI: 10.1016/j.devcel.2009.06.017] [Citation(s) in RCA: 263] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Revised: 06/01/2009] [Accepted: 06/30/2009] [Indexed: 01/17/2023]
Abstract
Dysfunction of lymphatic valves underlies human lymphedema, yet the
process of valve morphogenesis is poorly understood. Here, we show that during
embryogenesis lymphatic valve leaflet formation is initiated by upregulation of
integrin-α9 expression and deposition of its ligand, fibronectin-EIIIA
(FN-EIIIA), in the extracellular matrix. Endothelial cell specific deletion of
Itga9 (encoding integrin-α9) in mouse embryos
results in the development of rudimentary valve leaflets, characterized by
disorganized FN matrix, short cusps and retrograde lymphatic flow. Similar
morphological and functional defects are observed in mice lacking the EIIIA
domain of FN. Mechanistically, we demonstrate that in primary human lymphatic
endothelial cells the integrin-α9-EIIIA interaction directly regulates
FN fibril assembly, which is essential for the formation of the extracellular
matrix core of valve leaflets. Our findings reveal an important role for
integrin-α9 signaling during lymphatic valve morphogenesis and implicate
it as a candidate gene for primary lymphedema caused by valve defects.
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Affiliation(s)
- Eleni Bazigou
- Lymphatic Development Laboratory, Cancer Research UK London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
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123
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Sandig H, McDonald J, Gilmour J, Arno M, Lee TH, Cousins DJ. Fibronectin is a TH1-specific molecule in human subjects. J Allergy Clin Immunol 2009; 124:528-35, 535.e1-5. [PMID: 19541353 DOI: 10.1016/j.jaci.2009.04.036] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2008] [Revised: 04/28/2009] [Accepted: 04/28/2009] [Indexed: 12/26/2022]
Abstract
BACKGROUND T(H)1 cell-mediated immunity is essential for host defense against a variety of intracellular pathogens, such as mycobacteria, salmonella, and Leishmania species. A major T(H)1-mediated effector mechanism involves the IFN-gamma-induced killing of the pathogen by infected macrophages. OBJECTIVES The range of known T(H)1-specific effector molecules is limited, especially in human subjects. We sought to identify novel effector molecules that might be involved in T(H)1-mediated pathogen clearance. METHODS We performed microarray-based analysis of human T(H)1 and T(H)2 cells to identify T(H)1-specific molecules. These analyses identified the extracellular matrix molecule fibronectin as a highly expressed T(H)1-specific molecule. We examined the expression of fibronectin in a variety of human cell types by using real-time RT-PCR, ELISA, and Western blotting. We also studied the role of fibronectin in modulating monocyte phenotype using in vitro culture. RESULTS We show that human T(H)1 cells constitutively express and secrete fibronectin after in vitro differentiation from naive precursors. Furthermore, we demonstrate that ex vivo human T(H)1 cells selectively express fibronectin when compared with T(H)2 cells. The predominant isoform of fibronectin expressed by T(H)1 cells contains additional domains of the protein responsible for alpha4beta1 integrin binding and activation of Toll-like receptor 4. We show that treatment of monocytes with T(H)1 cell-derived fibronectin induces expression of the proinflammatory cytokine IL-6 while inhibiting IL-10 expression. CONCLUSIONS Because fibronectin also plays a major role in the attachment and opsonization of numerous intracellular pathogens, we propose that it might be a critical molecule produced by T(H)1 cells involved in pathogen eradication.
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Affiliation(s)
- Hilary Sandig
- Medical Research Council and Asthma UK Centre in Allergic Mechanisms of Asthma, King's College London, Guy's Hospital, London, United Kingdom
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124
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Alpha9 integrin promotes neurite outgrowth on tenascin-C and enhances sensory axon regeneration. J Neurosci 2009; 29:5546-57. [PMID: 19403822 DOI: 10.1523/jneurosci.0759-09.2009] [Citation(s) in RCA: 127] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Damaged CNS axons are prevented from regenerating by an environment containing many inhibitory factors. They also lack an integrin that interacts with tenascin-C, the main extracellular matrix glycoprotein of the CNS, which is upregulated after injury. The alpha9beta1 integrin heterodimer is a receptor for the nonalternatively spliced region of tenascin-C, but the alpha9 subunit is absent in adult neurons. In this study, we show that PC12 cells and adult rat dorsal root ganglion (DRG) neurons do not extend neurites on tenascin-C. However, after forced expression of alpha9 integrin, extensive neurite outgrowth from PC12 cells and adult rat DRG neurons occurs. Moreover, both DRG neurons and PC12 cells secrete tenascin-C, enabling alpha9-transfected cells to grow axons on tissue culture plastic. Using adeno-associated viruses to express alpha9 integrin in vivo in DRGs, we examined axonal regeneration after cervical dorsal rhizotomy or dorsal column crush in the adult rat. After rhizotomy, significantly more dorsal root axons regrew into the dorsal root entry zone at 6 weeks after injury in alpha9 integrin-expressing animals than in green fluorescent protein (GFP) controls. Similarly, after a dorsal column crush injury, there was significantly more axonal growth into the lesion site compared with GFP controls at 6 weeks after injury. Behavioral analysis after spinal cord injury revealed that both experimental and control groups had an increased withdrawal latency in response to mechanical stimulation when compared with sham controls; however, in response to heat stimulation, normal withdrawal latencies returned after alpha9 integrin treatment but remained elevated in control groups.
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125
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Contois L, Akalu A, Brooks PC. Integrins as "functional hubs" in the regulation of pathological angiogenesis. Semin Cancer Biol 2009; 19:318-28. [PMID: 19482089 DOI: 10.1016/j.semcancer.2009.05.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Accepted: 05/20/2009] [Indexed: 02/07/2023]
Abstract
It is well accepted that complex biological processes such as angiogenesis are not controlled by a single family of molecules or individually isolated signaling pathways. In this regard, new insight into the interconnected mechanisms that regulate angiogenesis might be gained by examining this process from a more global network perspective. The coordination of signaling cues from both outside and inside many different cell types is required for the successful completion of angiogenesis. Evidence is accumulating that the multifunctional integrin family of cell adhesion receptors represent an important group of molecules that play active roles in sensing, integrating, and distributing a diverse set of signals that regulate many cellular events required for angiogenesis. Given the ability of integrins to bind numerous extracellular ligands and transmit signals in a bi-directional fashion, we will discuss the multiple ways by which integrins may serve as a functional hub during pathological angiogenesis. In addition, we will highlight potential imaging and therapeutic strategies based on the expanding new insight into integrin function.
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Affiliation(s)
- Liangru Contois
- Maine Medical Center Research Institute, Center for Molecular Medicine, 81 Research Drive, Scarborough, ME 04074, United States
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126
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A novel fibronectin binding motif in MSCRAMMs targets F3 modules. PLoS One 2009; 4:e5412. [PMID: 19404402 PMCID: PMC2671840 DOI: 10.1371/journal.pone.0005412] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Accepted: 03/26/2009] [Indexed: 11/19/2022] Open
Abstract
Background BBK32 is a surface expressed lipoprotein and fibronectin (Fn)-binding microbial surface component recognizing adhesive matrix molecule (MSCRAMM) of Borrelia burgdorferi, the causative agent of Lyme disease. Previous studies from our group showed that BBK32 is a virulence factor in experimental Lyme disease and located the Fn-binding region to residues 21–205 of the lipoprotein. Methodology/Principal Findings Studies aimed at identifying interacting sites between BBK32 and Fn revealed an interaction between the MSCRAMM and the Fn F3 modules. Further analysis of this interaction showed that BBK32 can cause the aggregation of human plasma Fn in a similar concentration-dependent manner to that of anastellin, the superfibronectin (sFn) inducing agent. The resulting Fn aggregates are conformationally distinct from plasma Fn as indicated by a change in available thermolysin cleavage sites. Recombinant BBK32 and anastellin affect the structure of Fn matrices formed by cultured fibroblasts and inhibit endothelial cell proliferation similarly. Within BBK32, we have located the sFn-forming activity to a region between residues 160 and 175 which contains two sequence motifs that are also found in anastellin. Synthetic peptides mimicking these motifs induce Fn aggregation, whereas a peptide with a scrambled sequence motif was inactive, suggesting that these motifs represent the sFn-inducing sequence. Conclusions/Significance We conclude that BBK32 induces the formation of Fn aggregates that are indistinguishable from those formed by anastellin. The results of this study provide evidence for how bacteria can target host proteins to manipulate host cell activities.
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127
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Garmy-Susini B, Varner JA. Roles of integrins in tumor angiogenesis and lymphangiogenesis. Lymphat Res Biol 2009; 6:155-63. [PMID: 19093788 DOI: 10.1089/lrb.2008.1011] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The lifelong dedication of Dr. Judah Folkman to understand how tumors co-opt vasculature to promote tumor growth and spread resulted in the development of an astounding body of knowledge and development of new clinical therapeutics for cancer. Angiogenesis is a critical point in the development and dissemination of most human tumors. Tumor-associated lymphangiogenesis also plays an important role in mediating tumor spread to lymph nodes. The molecular regulations of these processes are complex, and many key molecular families have been implicated in the regulation of angiogenesis and lymphangiogenesis. By regulating cell-cell and cell-matrix contacts, integrins participate in blood and lymphatic vessel growth by promoting endothelial cell migration and survival. Understanding the underlying mechanisms by which integrins promote tumor-associated blood and lymphatic vessel development might provide important modalities for the therapeutic intervention of metastatic spread. This review focuses on the role of integrins in angiogenesis and lymphangiogenesis. Integrins represent potential targets for pharmacological agents and open new avenues for the control of metastatic spread in the treatment of malignancies. This article is dedicated to the memory of Dr. Judah Folkman, an amazing and caring teacher, scientist, physician, and friend.
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128
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Astrof S, Hynes RO. Fibronectins in vascular morphogenesis. Angiogenesis 2009; 12:165-75. [PMID: 19219555 DOI: 10.1007/s10456-009-9136-6] [Citation(s) in RCA: 186] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Accepted: 01/30/2009] [Indexed: 11/28/2022]
Abstract
Fibronectin is an extracellular matrix protein found only in vertebrate organisms containing endothelium-lined vasculature and is required for cardiovascular development in fish and mice. Fibronectin and its splice variants containing EIIIA and EIIIB domains are highly upregulated around newly developing vasculature during embryogenesis and in pathological conditions including atherosclerosis, cardiac hypertrophy, and tumorigenesis. However, their molecular roles in these processes are not entirely understood. We review genetic studies examining functions of fibronectin and its splice variants during embryonic cardiovascular development, and discuss potential roles of fibronectin in vascular disease and tumor angiogenesis.
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Affiliation(s)
- Sophie Astrof
- Greenberg Division of Cardiology, Department of Medicine, Weill Medical College of Cornell University, New York, NY 10065, USA.
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129
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Differences between the early and advanced stages of rheumatoid arthritis in the expression of EDA-containing fibronectin. Rheumatol Int 2009; 29:1397-401. [DOI: 10.1007/s00296-009-0866-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Accepted: 01/09/2009] [Indexed: 11/25/2022]
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130
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Ambesi A, McKeown-Longo PJ. Anastellin, the angiostatic fibronectin peptide, is a selective inhibitor of lysophospholipid signaling. Mol Cancer Res 2009; 7:255-65. [PMID: 19208746 DOI: 10.1158/1541-7786.mcr-08-0195] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Angiogenesis is regulated by integrin-dependent cell adhesion and the activation of specific cell surface receptors on vascular endothelial cells by angiogenic factors. Lysophosphatidic acid (LPA) and sphingosine-1 phosphate (S1P) are bioactive lysophospholipids that activate G protein-coupled receptors that stimulate phosphatidylinositol 3-kinase (PI3K), Ras, and Rho effector pathways involved in vascular cell survival, proliferation, adhesion, and migration. Previous studies have shown that anastellin, a fragment of the first type III module of fibronectin, functions as an antiangiogenic peptide suppressing tumor growth and metastasis. We have previously shown that anastellin blocks serum-dependent proliferation of microvessel endothelial cells (MVEC) by affecting extracellular signal-regulated kinase (ERK)-dependent G(1)-S transition. However, the mechanism by which anastellin regulates endothelial cell function remains unclear. In the present study, we mapped several lysophospholipid-mediated signaling pathways in MVEC and examined the effects of anastellin on LPA- and S1P-induced MVEC proliferation, migration, and cytoskeletal organization. Both LPA and S1P activated PI3K, Ras/ERK, and Rho/Rho kinase pathways, leading to migration, G(1)-S cell cycle progression, and stress fiber formation, respectively. Stimulation of proliferation by LPA/S1P occurred through a G(i)-dependent Ras/ERK pathway, which was independent of growth factor receptors and PI3K and Rho/Rho kinase signaling. Although LPA and S1P activated both PI3K/Akt and Ras/ERK signaling through G(i), anastellin inhibited only the Ras/ERK pathway. Stress fiber formation in response to LPA was dependent on Rho/Rho kinase but independent of G(i) and unaffected by anastellin. These results suggest that lysophospholipid mediators of G(i) activation leading to PI3K/Akt and Ras/ERK signaling bifurcate downstream of G(i) and that anastellin selectively inhibits the Ras/ERK arm of the pathway.
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Affiliation(s)
- Anthony Ambesi
- Center for Cell Biology and Cancer Research (MC-165), Albany Medical College, Albany, NY 12208, USA
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131
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White ES, Baralle FE, Muro AF. New insights into form and function of fibronectin splice variants. J Pathol 2008; 216:1-14. [PMID: 18680111 DOI: 10.1002/path.2388] [Citation(s) in RCA: 233] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The extracellular matrix (ECM) is a highly dynamic structure that not only provides a physical framework for cells within connective tissues, but also imparts instructive signals for development, tissue homeostasis and basic cell functions through its composition and ability to exert mechanical forces. The ECM of tissues is composed of, in addition to proteoglycans and hyaluronic acid, a number of proteins, most of which are generated after alternative splicing of their pre-mRNA. However, the precise function of these protein isoforms is still obscure in most cases. Fibronectin (FN), one of the main components of the ECM, is also one of the best-known examples of a family of proteins generated by alternative splicing, having at least 20 different isoforms in humans. Over the last few years, considerable progress on elucidating the functions of the alternatively spliced FN isoforms has been achieved with the essential development of key engineered mouse strains. Here we summarize the phenotypes of the mouse strains having targeted mutations in the FN gene, which may lead to novel insights linking function of alternatively spliced isoforms of fibronectin to human pathologies.
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Affiliation(s)
- E S White
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
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132
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Leiss M, Beckmann K, Girós A, Costell M, Fässler R. The role of integrin binding sites in fibronectin matrix assembly in vivo. Curr Opin Cell Biol 2008. [DOI: 10.1016/j.ceb.2008.06.001 doi:dx.doi.org] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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133
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134
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Abstract
Blood vessels promote tumour growth, and both blood and lymphatic vessels facilitate tumour metastasis by serving as conduits for the transport of tumour cells to new sites. Angiogenesis and lymphangiogenesis are regulated by integrins, which are members of a family of cell surface receptors whose ligands are extracellular matrix proteins and immunoglobulin superfamily molecules. Select integrins promote endothelial cell migration and survival during angiogenesis and lymphangiogenesis, whereas other integrins promote pro-angiogenic macrophage trafficking to tumours. Several integrin-targeted therapeutic agents are currently in clinical trials for cancer therapy. Here, we review the evidence implicating integrins as a family of fundamental regulators of angiogenesis and lymphangiogenesis.
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Affiliation(s)
- Christie J Avraamides
- Moores UCSD Cancer Center, 3,855 Health Sciences Drive, La Jolla, California 92092-0819, USA
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135
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Leiss M, Beckmann K, Girós A, Costell M, Fässler R. The role of integrin binding sites in fibronectin matrix assembly in vivo. Curr Opin Cell Biol 2008; 20:502-7. [PMID: 18586094 DOI: 10.1016/j.ceb.2008.06.001] [Citation(s) in RCA: 195] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Revised: 05/26/2008] [Accepted: 06/04/2008] [Indexed: 11/16/2022]
Abstract
The extracellular matrix (ECM) glycoprotein fibronectin (FN) requires the help of cells to assemble into a functional fibrillar matrix, which then orchestrates the assembly of other ECM proteins and promotes cell adhesion, migration and signalling. Fibrillogenesis is initiated and governed by cell surface integrins that bind to specific sites in the FN molecule. Recent studies identified novel integrin binding sites in FN that can also participate in FN fibril formation and in morphogenetic events during development.
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Affiliation(s)
- Michael Leiss
- Max Planck Institute of Biochemistry, Department of Molecular Medicine, 82152 Martinsried, Germany
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136
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Singh P, Chen C, Pal-Ghosh S, Stepp MA, Sheppard D, Van De Water L. Loss of integrin alpha9beta1 results in defects in proliferation, causing poor re-epithelialization during cutaneous wound healing. J Invest Dermatol 2008; 129:217-28. [PMID: 18633440 DOI: 10.1038/jid.2008.201] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The wound microenvironment comprises constituents, such as the extracellular matrix (ECM), that regulate with temporal and spatial precision, the migratory, proliferative, and contractility of wound cells. Prompt closure of the wound is an early and critical phase of healing and beta1 integrins are important in this process. We previously reported a marked increase in integrin alpha9beta1 expression in epidermal keratinocytes in cutaneous and corneal wounds. However, the functional role of keratinocyte alpha9beta1 during re-epithelialization is unknown and analysis has been precluded by the lethal phenotype of integrin alpha9beta1 knockout mice. We now report that in conditional integrin alpha9 knockout (K14-alpha9 null) mice, normal proliferation occurs in epidermal keratinocytes and corneal basal cells. Normal epidermal keratinocyte morphology is also retained. However, corneal basal cell morphology and epithelial thickness are altered, suggesting that loss of integrin alpha9beta1 results in abnormal corneal differentiation. In cutaneous wounds, the number of proliferating epidermal keratinocytes is significantly reduced in K14-alpha9 null mice compared with alpha9(fl/-) mice, but not in Cre (control) mice. The decreased keratinocyte proliferation observed in K14-alpha9 null mice negatively impacts healing, resulting in a thinner migrating epithelium, demonstrating that alpha9beta1 is crucial for efficient and proper re-epithelialization during cutaneous wound healing.
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Affiliation(s)
- Purva Singh
- Center for Cell Biology and Cancer Research, Albany Medical College, Albany, New York 12208, USA
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137
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Shinde AV, Bystroff C, Wang C, Vogelezang MG, Vincent PA, Hynes RO, Van De Water L. Identification of the Peptide Sequences within the EIIIA (EDA) Segment of Fibronectin That Mediate Integrin α9β1-dependent Cellular Activities. J Biol Chem 2008; 283:2858-70. [DOI: 10.1074/jbc.m708306200] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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138
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Babaev VR, Porro F, Linton MF, Fazio S, Baralle FE, Muro AF. Absence of regulated splicing of fibronectin EDA exon reduces atherosclerosis in mice. Atherosclerosis 2007; 197:534-40. [PMID: 17897651 PMCID: PMC2358924 DOI: 10.1016/j.atherosclerosis.2007.08.015] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Revised: 07/19/2007] [Accepted: 08/02/2007] [Indexed: 11/16/2022]
Abstract
Atherosclerotic lesions are characterized by a profound alteration in the architecture of the arterial intima, with a marked increase of fibronectin (FN) and the appearance of the alternatively spliced FN variant containing the extra domain A (EDA). To analyze the role of FN isoforms in atherosclerotic lesion formation we utilized mouse strains devoid of EDA exon regulated splicing, which constitutively include (EDA(+/+)) or exclude (EDA(-/-)) the exon. Both mutant mice had a 40% reduction in atherosclerotic lesions after the atherogenic-diet treatment (mean+/-S.E., microm(2); 22969+/-2185; 13660+/-1533; 14260+/-2501 for EDA(wt/wt), EDA(+/+) and EDA(-/-), respectively; p< or =0.01 ANOVA test) associated to a lower capacity of macrophages to uptake modified LDL and undergo foam-cell formation. Lesions in control mice were more numerous and bigger, with augmented and deeper macrophage infiltration, and increased FN expression in the sub-endothelial area. Previous experiments have shown that apoE(-/-)EDA(-/-) mice have a decreased number and size of atherosclerotic lesions and, on this basis, it has been proposed that the EDA domain has a pro-atherogenic role. Our data with the EDA(+/+) mice rules out this hypothesis and suggest that regulated splicing of the EDA exon of the FN gene is involved in progression of atherosclerosis, highlighting the importance of alternative splicing in regulating cellular processes.
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Affiliation(s)
- Vladimir R Babaev
- Department of Medicine, Vanderbilt University Medical Center, TN, USA
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139
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Astrof S, Crowley D, Hynes RO. Multiple cardiovascular defects caused by the absence of alternatively spliced segments of fibronectin. Dev Biol 2007; 311:11-24. [PMID: 17706958 PMCID: PMC2080666 DOI: 10.1016/j.ydbio.2007.07.005] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2007] [Revised: 07/06/2007] [Accepted: 07/06/2007] [Indexed: 10/23/2022]
Abstract
Alternatively spliced variants of fibronectin (FN) containing exons EIIIA and EIIIB are expressed around newly forming vessels in development and disease but are downregulated in mature vasculature. The sequences and patterns of expression of these splice variants are highly conserved among vertebrates, suggestive of their biological importance; however the functions of EIIIA and EIIIB-containing FNs are unknown. To understand the role(s) of these splice variants, we deleted both EIIIA and EIIIB exons from the FN gene and observed embryonic lethality with incomplete penetrance by embryonic day 10.5. Deletion of both EIIIA and EIIIB exons did not affect synthesis or cell surface deposition of FN, indicating that embryonic lethality was due specifically to the absence of EIIIA and EIIIB exons from FN. EIIIA/EIIIB double-null embryos displayed multiple embryonic cardiovascular defects, including vascular hemorrhage, failure of remodeling embryonic and yolk sac vasculature, defective placental angiogenesis and heart defects. In addition, we observed defects in coverage and association with dorsal aortae of alpha-smooth-muscle-actin-positive cells. Our studies indicate that the presence or absence of EIIIA and EIIIB exons alters the function of FN and demonstrate the requirement for these alternatively spliced exons in cardiovascular development.
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Affiliation(s)
- Sophie Astrof
- Howard Hughes Medical Institute, Center for Cancer Research, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
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140
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Abstract
Vascular development requires correct interactions among endothelial cells, pericytes and surrounding cells. These interactions involve many cell adhesion interactions, including cell-matrix interactions both with basement membranes and with surrounding extracellular matrices. Investigations of the contributions of these various interactions in vascular development and angiogenesis have been rather uneven and incomplete over the past 10-15 years. There has been considerable concentration on a few receptors, matrix proteins and proteolytic fragments with the goal of finding means to control angiogenesis. Many other potential contributors have received much less attention. Even for those molecules that have been subject to intensive investigation, our knowledge is incomplete. This review will survey the spectrum of extracellular matrix (ECM) proteins and cell-matrix adhesion receptors (particularly integrins) that are likely to contribute to angiogenesis and discuss what is known and not known about the roles of each of them.
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Affiliation(s)
- R O Hynes
- Howard Hughes Medical Institute, Center for Cancer Research, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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141
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Keselowsky BG, Bridges AW, Burns KL, Tate CC, Babensee JE, LaPlaca MC, García AJ. Role of plasma fibronectin in the foreign body response to biomaterials. Biomaterials 2007; 28:3626-31. [PMID: 17521718 PMCID: PMC1950471 DOI: 10.1016/j.biomaterials.2007.04.035] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Accepted: 04/13/2007] [Indexed: 11/28/2022]
Abstract
Host responses to biomaterials control the biological performance of implanted medical devices. Upon implantation, synthetic materials adsorb biomolecules, which trigger an inflammatory cascade comprising coagulation, leukocyte recruitment/adhesion, and foreign body reaction. The foreign body reaction and ensuing fibrous encapsulation severely limit the in vivo performance of numerous biomedical devices. While it is well established that plasma fibrinogen and secreted cytokines modulate leukocyte recruitment and maturation into foreign body giant cells, mediators of chronic inflammation and fibrous encapsulation of implanted biomaterials remain poorly understood. Using plasma fibronectin (pFN) conditional knock-out mice, we demonstrate that pFN modulates the foreign body response to polyethylene terephthalate disks implanted subcutaneously. Fibrous collagenous capsules were two-fold thicker in mice depleted of pFN compared to controls. In contrast, deletion of pFN did not alter acute leukocyte recruitment to the biomaterial, indicating that pFN modulates chronic fibrotic responses. The number of foreign body giant cells associated with the implant was three times higher in the absence of pFN while macrophage numbers were not different, suggesting that pFN regulates the formation of biomaterial-associated foreign body giant cells. Interestingly, cellular FN (cFN) was present in the capsules of both normal and pFN-depleted mice, suggesting that cFN could not compensate for the loss of pFN. These results implicate pFN in the host response to implanted materials and identify a potential target for therapeutic intervention to enhance the biological performance of biomedical devices.
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Affiliation(s)
- Benjamin G. Keselowsky
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta GA 30332
- Department of Biomedical Engineering, University of Florida, Gainesville FL 32611
| | - Amanda W. Bridges
- Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta GA 30332
| | - Kellie L. Burns
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta GA 30332
| | - Ciara C. Tate
- Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta GA 30332
| | - Julia E. Babensee
- Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta GA 30332
| | - Michelle C. LaPlaca
- Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta GA 30332
| | - Andrés J. García
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta GA 30332
- Corresponding author: Andrés J. García, Ph.D., Petit Institute for Bioengineering and Bioscience, 315 Ferst Drive, 2314 IBB, Atlanta, GA 30332-0363, Tel: 404-894-9384; Fax: 404-385-1397;
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142
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Horowitz JC, Rogers DS, Sharma V, Vittal R, White ES, Cui Z, Thannickal VJ. Combinatorial activation of FAK and AKT by transforming growth factor-beta1 confers an anoikis-resistant phenotype to myofibroblasts. Cell Signal 2006; 19:761-71. [PMID: 17113264 PMCID: PMC1820832 DOI: 10.1016/j.cellsig.2006.10.001] [Citation(s) in RCA: 195] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2006] [Revised: 09/18/2006] [Accepted: 10/01/2006] [Indexed: 10/23/2022]
Abstract
Transforming growth factor-beta (TGF-beta) is a prototypical tumour-suppressor cytokine with cytostatic and pro-apoptotic effects on most target cells; however, mechanisms of its pro-survival/anti-apoptotic signalling in certain cell types and contexts remain unclear. In human lung fibroblasts, TGF-beta1 is known to induce myofibroblast differentiation in association with the delayed activation of focal adhesion kinase (FAK) and protein kinase B (PKB/AKT). Here, we demonstrate that FAK and AKT are independently regulated by early activation of SMAD3 and p38 MAPK, respectively. Pharmacologic or genetic approaches that disrupt SMAD3 signalling block TGF-beta1-induced activation of FAK, but not AKT; in contrast, disruption of early p38 MAPK signalling abrogates AKT activation, but does not alter FAK activation. TGF-beta1 is able to activate AKT in cells expressing mutant FAK or in cells treated with an RGD-containing peptide that interferes with integrin signalling, inhibits FAK activation and induces anoikis (apoptosis induced by loss of adhesion signalling). TGF-beta1 protects myofibroblasts from anoikis, in part, by activation of the PI3K-AKT pathway. Thus, TGF-beta1 co-ordinately and independently activates the FAK and AKT protein kinase pathways to confer an anoikis-resistant phenotype to myofibroblasts. Activation of these pro-survival/anti-anoikis pathways in myofibroblasts likely contributes to essential roles of TGF-beta1 in tissue fibrosis and tumour-promotion.
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Affiliation(s)
| | | | | | | | | | | | - Victor J. Thannickal
- *Corresponding author. Tel.: +1 734 936 9371; fax: +1 734 764 2655. E-mail address: (V.J. Thannickal)
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143
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Pajoohesh-Ganji A, Pal-Ghosh S, Simmens SJ, Stepp MA. Integrins in slow-cycling corneal epithelial cells at the limbus in the mouse. Stem Cells 2005; 24:1075-86. [PMID: 16282441 DOI: 10.1634/stemcells.2005-0382] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Adult corneal epithelial stem cells (CESCs) have been shown to reside at the periphery of the cornea at a site called the corneoscleral junction or limbus. Although studies have shown that these cells are slow cycling, their molecular characteristics are not well understood. Using a whole-mount procedure, we show that whereas alpha9-integrin is present in a subset of the basal cells at the corneal limbus and absent in the central cornea, beta1-, beta4-, alpha3-, and alpha6-integrins are more highly expressed overall in central corneal basal cells. To characterize CESCs based on their slow-cycling nature, we simultaneously evaluated 5-bromo-2-deoxyuridine (BrdU) label-retaining cells (LRCs) and integrin expression (alpha9, beta1, and beta4) in a total of 1,889 cells at the limbus of adult mice that had been injected as neonates with BrdU. Whereas the LRCs were usually observed adjacent to alpha9-integrin-positive cells, most LRCs were alpha9-integrin-negative and expressed high levels of beta1- and beta4-integrin. In addition, we observed more BrdU-positive LRCs at the superior and inferior quadrants of adult mouse corneas than at the nasal and temporal quadrants, and determined that 0.94 to 3.6% of the limbal basal cells were slow cycling. We conclude from these data that the slow-cycling LRCs in the adult mouse cornea are enriched in cells that express high levels of beta1- and beta4-integrin and little alpha9-integrin.
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Affiliation(s)
- Ahdeah Pajoohesh-Ganji
- Department of Anatomy and Cell Biology, The George Washington University Medical Center, 2300 I Street NW, Washington, DC 20037, USA
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144
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Fededa JP, Petrillo E, Gelfand MS, Neverov AD, Kadener S, Nogués G, Pelisch F, Baralle FE, Muro AF, Kornblihtt AR. A polar mechanism coordinates different regions of alternative splicing within a single gene. Mol Cell 2005; 19:393-404. [PMID: 16061185 DOI: 10.1016/j.molcel.2005.06.035] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2004] [Revised: 03/14/2005] [Accepted: 06/30/2005] [Indexed: 11/20/2022]
Abstract
Alternative splicing plays a key role in generating protein diversity. Transfections with minigenes revealed coordination between two distant, alternatively spliced exons in the same gene. Mutations that either inhibit or stimulate inclusion of the upstream alternative exon deeply affect inclusion of the downstream one. However, similar mutations at the downstream alternative exon have little effect on the upstream one. This polar effect is promoter specific and is enhanced by inhibition of transcriptional elongation. Consistently, cells from mutant mice with either constitutive or null inclusion of a fibronectin alternative exon revealed coordination with a second alternative splicing region, located far downstream. Using allele-specific RT-PCR, we demonstrate that this coordination occurs in cis and is also affected by transcriptional elongation rates. Bioinformatics supports the generality of these findings, indicating that 25% of human genes contain multiple alternative splicing regions and identifying several genes with nonrandom distribution of mRNA isoforms at two alternative regions.
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Affiliation(s)
- Juan P Fededa
- Laboratorio de Fisiología y Biología Molecular, Departamento de Fisiología, Biología Molecular y Celular, IFIBYNE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
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145
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Mao Y, Schwarzbauer JE. Fibronectin fibrillogenesis, a cell-mediated matrix assembly process. Matrix Biol 2005; 24:389-99. [PMID: 16061370 DOI: 10.1016/j.matbio.2005.06.008] [Citation(s) in RCA: 551] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2005] [Accepted: 06/21/2005] [Indexed: 11/21/2022]
Abstract
The extracellular matrix provides a framework for cell adhesion, supports cell movement, and serves to compartmentalize tissues into functional units. Fibronectin is a core component of many extracellular matrices where it regulates a variety of cell activities through direct interactions with cell surface integrin receptors. Fibronectin is synthesized by many adherent cells which then assemble it into a fibrillar network. The assembly process is integrin-dependent and fibronectin-integrin interactions initiate a step-wise process involving conformational activation of fibronectin outside and organization of the actin cytoskeleton inside. During assembly, fibronectin undergoes conformational changes that expose fibronectin-binding sites and promote intermolecular interactions needed for fibril formation. In this review, the main steps of fibronectin assembly are described and recent studies on fibronectin conformational changes are discussed.
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Affiliation(s)
- Yong Mao
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544-1014, United States
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146
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Abstract
Fibronectin is known to stimulate cell growth and migration, but research does not provide a complete picture of all the mechanisms involved. Further studies are needed before practitioners can apply in vitro results to in vivo environments.
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Affiliation(s)
- S L Briggs
- Royal Surrey County Hospital, Guildford, UK.
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147
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Pelisch F, Blaustein M, Kornblihtt AR, Srebrow A. Cross-talk between signaling pathways regulates alternative splicing: a novel role for JNK. J Biol Chem 2005; 280:25461-9. [PMID: 15886203 DOI: 10.1074/jbc.m412007200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The regulation of alternative splicing by extracellular signals represents a key event in the control of gene expression. There is increasing evidence showing that many extracellular cues regulate alternative splicing. Nevertheless, the broad picture regarding the role of different signaling pathways and their interaction remains incomplete. Using the fibronectin gene as a model, we show that a laminin-rich basement membrane regulates the alternative splicing of two out of three regions of the transcript (extra domain I and type III connecting segment) in mammary epithelial cells, through a non-stress c-Jun N-terminal kinase (JNK) signaling pathway. We propose that dephosphorylation of the extracellular signal-regulated kinase is involved in this regulatory process. Furthermore, the laminin-rich basement membrane blocks the effect of a mammary mesenchymal cell-conditioned medium, which stimulates the inclusion of extra domain I and type III connecting segment through a phosphatidylinositol3-kinase-dependent cascade, indicating that JNK signaling can inhibit the phosphatidylinositol 3-kinase-mediated splicing regulation. These results implicate JNK in the regulation of alternative splicing and provide new evidence on how extracellular stimuli are converted into changes in splicing patterns, strengthening the view that the control of alternative splicing is as complex and relevant as transcriptional control, together accounting for the spatiotemporal requirements of gene expression.
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Affiliation(s)
- Federico Pelisch
- Biología Molecular y Neurociencias-Consejo Nacional de Investigaciones Científicas y Técnicas, Departamento de Fisiología, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
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148
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Singh P, Reimer CL, Peters JH, Stepp MA, Hynes RO, Van De Water L. The Spatial and Temporal Expression Patterns of Integrin α9β1 and One of Its Ligands, the EIIIA Segment of Fibronectin, in Cutaneous Wound Healing. J Invest Dermatol 2004; 123:1176-81. [PMID: 15610531 DOI: 10.1111/j.0022-202x.2004.23485.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The fibronectins (FN) comprise a family of adhesive extracellular matrix proteins thought to mediate important functions in cutaneous wounds. Plasma fibronectin (pFN) extravasates for days from intact hyperpermeable vessels following injury whereas mRNAs encoding the cellular fibronectins (cFN) that include two segments, termed EIIIA (EDA) and EIIIB (EDB), are expressed by wound cells. Wounds in mice null for pFN appear to heal normally whereas those in EIIIA null mice exhibit defects, suggesting that cFN may play a role when pFN is missing. Integrin alpha9beta1, a receptor for several extracellular matrix proteins as well as the EIIIA segment, is expressed normally in the basal layer of squamous epithelia. We report results from immunohistochemistry on healing wounds demonstrating that EIIIA-containing cFN are deposited abundantly but transiently from day 4 to 7 whereas EIIIB-containing cFN persist at least through day 14. Elevated expression of alpha9beta1 is seen in basal and suprabasal epidermal keratinocytes in wounds. The spatial expression patterns of cFN and alpha9beta1 are distinct, but overlap in the dermal-epidermal junction, and both are expressed contemporaneously. These observations suggest a role for alpha9beta1-EIIIA interactions in wound keratinocyte function.
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Affiliation(s)
- Purva Singh
- Center for Cell Biology and Cancer Research, Albany Medical College, Albany, New York, USA
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149
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Chen C, Young BA, Coleman CS, Pegg AE, Sheppard D. Spermidine/spermine N1-acetyltransferase specifically binds to the integrin alpha9 subunit cytoplasmic domain and enhances cell migration. ACTA ACUST UNITED AC 2004; 167:161-70. [PMID: 15479742 PMCID: PMC2172529 DOI: 10.1083/jcb.200312166] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The integrin α9β1 is expressed on migrating cells, such as leukocytes, and binds to multiple ligands that are present at sites of tissue injury and inflammation. α9β1, like the structurally related integrin α4β1, mediates accelerated cell migration, an effect that depends on the α9 cytoplasmic domain. α4β1 enhances migration through reversible binding to the adapter protein, paxillin, but α9β1-dependent migration is paxillin independent. Using yeast two-hybrid screening, we identified the polyamine catabolizing enzyme spermidine/spermine N1-acetyltransferase (SSAT) as a specific binding partner of the α9 cytoplasmic domain. Overexpression of SSAT increased α9β1-mediated migration, and small interfering RNA knockdown of SSAT inhibited this migration without affecting cell adhesion or migration that was mediated by other integrin cytoplasmic domains. The enzyme activity of SSAT is critical for this effect, because a catalytically inactive version did not enhance migration. We conclude that SSAT directly binds to the α9 cytoplasmic domain and mediates α9-dependent enhancement of cell migration, presumably by localized effects on acetylation of polyamines or of unidentified substrates.
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Affiliation(s)
- Chun Chen
- Lung Biology Center, Department of Medicine, University of California-San Francisco, San Francisco, CA 94110, USA
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150
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Havrlikova K, Mellott M, Kaufman AH, Loredo GA, Peters JH, Colvin RB, Foster CS. Expression of Fibronectin Isoforms Bearing the Alternatively Spliced EIIIA, EIIIB, and V Segments in Corneal Alkali Burn and Keratectomy Wound Models in the Rat. Cornea 2004; 23:812-8. [PMID: 15502483 DOI: 10.1097/01.ico.0000133988.34274.24] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To better understand the healing process in the wounded cornea, fibronectin (FN) isoforms bearing the alternatively spliced EIIIA, EIIIB, and V segments (EIIIA+, EIIIB+, and V+ FNs) were evaluated in alkali burn and keratectomy wound models in the rat. METHODS Alkali burn or keratectomy wounds (both 2 mm) were created, and corneas were harvested at various time points and analyzed by indirect immunofluorescence using antibodies specific for the EIIIA, EIIIB, and V segments as well as for the total pool of FN (total FN). RESULTS There was minimal staining for any variety of FN in the epithelium or basement membrane zone (BMZ) in normal cornea, but each antibody produced granular staining in the stroma. Bright staining for V+ and total FNs was evident at the denuded stromal surface 1 day following keratectomy. In contrast, staining for EIIIA+ and EIIIB+ FNs was negligible at 24 hours but appeared on the wound surface under the migrating unstained epithelium by the second day. BMZ staining for FN then gradually subsided, such that there was little or no staining by 6 weeks. In contrast, alkali burn wounds exhibited very little BMZ staining throughout the time course. Although there was preferential staining of the anterior aspect of Descemet membrane by anti-EIIIA and anti-EIIIB antibodies under normal conditions, the staining intensity of the anterior and posterior aspects became similar following corneal wounding. CONCLUSION Deposition of EIIIA+ and EIIIB+ FNs in the BMZ of the keratectomy wound occurs more slowly than deposition of V+ and total FNs. EIIIA+ FN is expressed in a distribution that overlaps with that previously described for the alpha 9 integrin subunit following corneal debridement, suggesting that EIIIA-alpha 9 interactions could occur during corneal wound healing. In contrast, the relative lack of FN deposition in alkali burn wounds suggests that proteolytic degradation of FN may occur; and this, along with impairment of new FN synthesis because of cellular damage, could play a role in the high prevalence of recurrent epithelial erosions in alkali-wounded corneas.
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Affiliation(s)
- Katerina Havrlikova
- Hilles Immunology Laboratory, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA 02114, USA
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