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Procknow SS, Kozel BA. Emerging mechanisms of elastin transcriptional regulation. Am J Physiol Cell Physiol 2022; 323:C666-C677. [PMID: 35816641 PMCID: PMC9448287 DOI: 10.1152/ajpcell.00228.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 07/06/2022] [Accepted: 07/06/2022] [Indexed: 11/22/2022]
Abstract
Elastin provides recoil to tissues that stretch such as the lung, blood vessels, and skin. It is deposited in a brief window starting in the prenatal period and extending to adolescence in vertebrates, and then slowly turns over. Elastin insufficiency is seen in conditions such as Williams-Beuren syndrome and elastin-related supravalvar aortic stenosis, which are associated with a range of vascular and connective tissue manifestations. Regulation of the elastin (ELN) gene occurs at multiple levels including promoter activation/inhibition, mRNA stability, interaction with microRNAs, and alternative splicing. However, these mechanisms are incompletely understood. Better understanding of the processes controlling ELN gene expression may improve medicine's ability to intervene in these rare conditions, as well as to replace age-associated losses by re-initiating elastin production. This review describes what is known about the ELN gene promoter structure, transcriptional regulation by cytokines and transcription factors, and posttranscriptional regulation via mRNA stability and micro-RNA and highlights new approaches that may influence regenerative medicine.
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Affiliation(s)
- Sara S Procknow
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri
| | - Beth A Kozel
- Translational Vascular Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
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Tatler AL, Habgood A, Porte J, John AE, Stavrou A, Hodge E, Kerama-Likoko C, Violette SM, Weinreb PH, Knox AJ, Laurent G, Parfrey H, Wolters PJ, Wallace W, Alberti S, Nordheim A, Jenkins G. Reduced Ets Domain-containing Protein Elk1 Promotes Pulmonary Fibrosis via Increased Integrin αvβ6 Expression. J Biol Chem 2016; 291:9540-53. [PMID: 26861876 PMCID: PMC4850293 DOI: 10.1074/jbc.m115.692368] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 02/09/2016] [Indexed: 12/20/2022] Open
Abstract
Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease with high mortality. Active TGFβ1 is considered central to the pathogenesis of IPF. A major mechanism of TGFβ1 activation in the lung involves the epithelially restricted αvβ6 integrin. Expression of the αvβ6 integrin is dramatically increased in IPF. How αvβ6 integrin expression is regulated in the pulmonary epithelium is unknown. Here we identify a region in the β6 subunit gene (ITGB6) promoter acting to markedly repress basal gene transcription, which responds to both the Ets domain-containing protein Elk1 (Elk1) and the glucocorticoid receptor (GR). Both Elk1 and GR can regulate αvβ6 integrin expression in vitro We demonstrate Elk1 binding to the ITGB6 promoter basally and that manipulation of Elk1 or Elk1 binding alters ITGB6 promoter activity, gene transcription, and αvβ6 integrin expression. Crucially, we find that loss of Elk1 causes enhanced Itgb6 expression and exaggerated lung fibrosis in an in vivo model of fibrosis, whereas the GR agonist dexamethasone inhibits Itgb6 expression. Moreover, Elk1 dysregulation is present in epithelium from patients with IPF. These data reveal a novel role for Elk1 regulating ITGB6 expression and highlight how dysregulation of Elk1 can contribute to human disease.
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Affiliation(s)
- Amanda L Tatler
- From the Division of Respiratory Medicine, University of Nottingham, Nottingham University Hospitals, City Campus, Nottingham NG5 1PB, United Kingdom,
| | - Anthony Habgood
- From the Division of Respiratory Medicine, University of Nottingham, Nottingham University Hospitals, City Campus, Nottingham NG5 1PB, United Kingdom
| | - Joanne Porte
- From the Division of Respiratory Medicine, University of Nottingham, Nottingham University Hospitals, City Campus, Nottingham NG5 1PB, United Kingdom
| | - Alison E John
- From the Division of Respiratory Medicine, University of Nottingham, Nottingham University Hospitals, City Campus, Nottingham NG5 1PB, United Kingdom
| | - Anastasios Stavrou
- From the Division of Respiratory Medicine, University of Nottingham, Nottingham University Hospitals, City Campus, Nottingham NG5 1PB, United Kingdom
| | - Emily Hodge
- From the Division of Respiratory Medicine, University of Nottingham, Nottingham University Hospitals, City Campus, Nottingham NG5 1PB, United Kingdom
| | - Cheryl Kerama-Likoko
- From the Division of Respiratory Medicine, University of Nottingham, Nottingham University Hospitals, City Campus, Nottingham NG5 1PB, United Kingdom
| | | | | | - Alan J Knox
- From the Division of Respiratory Medicine, University of Nottingham, Nottingham University Hospitals, City Campus, Nottingham NG5 1PB, United Kingdom
| | - Geoffrey Laurent
- the Centre for Respiratory Research, University College London, London WC1E 6JF, United Kingdom, the Centre for Cell Therapy and Regenerative Medicine, University of Western Australia, Crawley WA 6009, Australia
| | - Helen Parfrey
- the Department of Medicine, University of Cambridge and Papworth Hospital NHSFT, Cambridge CB2 0SP, United Kingdom
| | - Paul John Wolters
- the Department of Medicine, University of California, San Francisco, San Francisco, California 94143
| | - William Wallace
- the Division of Pathology, University of Edinburgh, Edinburgh EH4 2XR, United Kingdom, and
| | - Siegfried Alberti
- the Interfaculty Institute of Cell Biology, Tübingen University, Tübingen 72076, Germany
| | - Alfred Nordheim
- the Interfaculty Institute of Cell Biology, Tübingen University, Tübingen 72076, Germany
| | - Gisli Jenkins
- From the Division of Respiratory Medicine, University of Nottingham, Nottingham University Hospitals, City Campus, Nottingham NG5 1PB, United Kingdom
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3
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Lannoy M, Slove S, Louedec L, Choqueux C, Journé C, Michel JB, Jacob MP. Inhibition of ERK1/2 Phosphorylation: A New Strategy to Stimulate Elastogenesis in the Aorta. Hypertension 2014; 64:423-30. [DOI: 10.1161/hypertensionaha.114.03352] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Morgane Lannoy
- From INSERM, U1148, Hôpital Bichat, Paris F-75018, France (M.L., S.S., L.L., C.C., C.J., J.-B.M., M.-P.J.); Univ Paris Diderot, Sorbonne Paris Cité, Paris F-75018, France (M.L., S.S., C.C., C.J., J.-B.M.); and Fédération de Recherche en Imagerie Multimodalité, Paris F-75018, France (C.J.)
| | - Séverin Slove
- From INSERM, U1148, Hôpital Bichat, Paris F-75018, France (M.L., S.S., L.L., C.C., C.J., J.-B.M., M.-P.J.); Univ Paris Diderot, Sorbonne Paris Cité, Paris F-75018, France (M.L., S.S., C.C., C.J., J.-B.M.); and Fédération de Recherche en Imagerie Multimodalité, Paris F-75018, France (C.J.)
| | - Liliane Louedec
- From INSERM, U1148, Hôpital Bichat, Paris F-75018, France (M.L., S.S., L.L., C.C., C.J., J.-B.M., M.-P.J.); Univ Paris Diderot, Sorbonne Paris Cité, Paris F-75018, France (M.L., S.S., C.C., C.J., J.-B.M.); and Fédération de Recherche en Imagerie Multimodalité, Paris F-75018, France (C.J.)
| | - Christine Choqueux
- From INSERM, U1148, Hôpital Bichat, Paris F-75018, France (M.L., S.S., L.L., C.C., C.J., J.-B.M., M.-P.J.); Univ Paris Diderot, Sorbonne Paris Cité, Paris F-75018, France (M.L., S.S., C.C., C.J., J.-B.M.); and Fédération de Recherche en Imagerie Multimodalité, Paris F-75018, France (C.J.)
| | - Clément Journé
- From INSERM, U1148, Hôpital Bichat, Paris F-75018, France (M.L., S.S., L.L., C.C., C.J., J.-B.M., M.-P.J.); Univ Paris Diderot, Sorbonne Paris Cité, Paris F-75018, France (M.L., S.S., C.C., C.J., J.-B.M.); and Fédération de Recherche en Imagerie Multimodalité, Paris F-75018, France (C.J.)
| | - Jean-Baptiste Michel
- From INSERM, U1148, Hôpital Bichat, Paris F-75018, France (M.L., S.S., L.L., C.C., C.J., J.-B.M., M.-P.J.); Univ Paris Diderot, Sorbonne Paris Cité, Paris F-75018, France (M.L., S.S., C.C., C.J., J.-B.M.); and Fédération de Recherche en Imagerie Multimodalité, Paris F-75018, France (C.J.)
| | - Marie-Paule Jacob
- From INSERM, U1148, Hôpital Bichat, Paris F-75018, France (M.L., S.S., L.L., C.C., C.J., J.-B.M., M.-P.J.); Univ Paris Diderot, Sorbonne Paris Cité, Paris F-75018, France (M.L., S.S., C.C., C.J., J.-B.M.); and Fédération de Recherche en Imagerie Multimodalité, Paris F-75018, France (C.J.)
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Abstract
Underlying the dynamic regulation of tropoelastin expression and elastin formation in development and disease are transcriptional and post-transcriptional mechanisms that have been the focus of much research. Of particular importance is the cytokine-governed elastin regulatory axis in which the pro-elastogenic activities of transforming growth factor β-1 (TGFβ1) and insulin-like growth factor-I (IGF-I) are opposed by anti-elastogenic activities of basic fibroblast growth factor (bFGF/FGF-2), heparin-binding epidermal growth factor-like growth factor (HB-EGF), EGF, PDGF-BB, TGFα, tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β and noncanonical TGFβ1 signaling. A key mechanistic feature of the regulatory axis is that cytokines influence elastin formation through effects on the cell cycle involving control of cyclin-cyclin dependent kinase complexes and activation of the Ras/MEK/ERK signaling pathway. In this article we provide an overview of the major cytokines/growth factors that modulate elastogenesis and describe the underlying molecular mechanisms for their action on elastin production.
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Affiliation(s)
- Erin P Sproul
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC 29425, USA.
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Chaturvedi S, Hass R. Extracellular signals in young and aging breast epithelial cells and possible connections to age-associated breast cancer development. Mech Ageing Dev 2011; 132:213-9. [PMID: 21507328 DOI: 10.1016/j.mad.2011.04.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Revised: 02/07/2011] [Accepted: 04/02/2011] [Indexed: 12/28/2022]
Abstract
Aging of human breast tissue is accompanied by certain structural and functional variations and several studies suggest a possible contribution of these changes to an aging-related breast cancer development. At the cellular level, aging of human mammary epithelial cells is associated with significant morphological and functional alterations such as an increased cell size and a reduced proliferation. Cellular senescence of HMEC cannot be explained by a single mechanism but represents an interaction of numerous extra- and intracellular events and the complexity of such orchestrating pathways is still hardly understood. Besides the contribution of reactive oxygen species and telomere dysfunction to aging, it is the aim of this mini-review, to compare distinct changes to extracellular signals by certain matrix metalloproteinases including MMP-7 and associated growth factor pathways mediated by HB-EGF activation in young and aging HMEC. Such changes can alter hormone receptor levels within aged HMEC, induce tissue fibrosis and promote epithelial-to-mesenchymal transition as a potential prerequisite for breast cancer development. Moreover, an accumulation of aging cells during the normal life span of the breast tissue may also substantially effect and interact with adjacent neighboring populations in the local microenvironment to provide optimized growth conditions which would also support neoplastic cells.
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Affiliation(s)
- Sukhada Chaturvedi
- Department of Gynecology, Biochemistry and Tumor Biology Lab (OE 6411), Medical School Hannover, Germany.
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6
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Im HJ, Sharrocks AD, Lin X, Yan D, Kim J, van Wijnen AJ, Hipskind RA. Basic fibroblast growth factor induces matrix metalloproteinase-13 via ERK MAP kinase-altered phosphorylation and sumoylation of Elk-1 in human adult articular chondrocytes. Open Access Rheumatol 2009; 1:151-161. [PMID: 27789988 PMCID: PMC5074718 DOI: 10.2147/oarrr.s7527] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Degradation of the extracellular matrix (ECM) by matrix metalloproteinases (MMPs) and release of basic fibroblast growth factor (bFGF) are principal aspects of the pathology of osteoarthritis (OA). ECM disruption leads to bFGF release, which activates the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) pathway and its downstream target the Ets-like transcription factor Elk-1. Previously we demonstrated that the bFGF-ERK-Elk-1 signaling axis is responsible for the potent induction of MMP-13 in human primary articular chondrocytes. Here we report that, in addition to phosphorylation of Elk-1, dynamic posttranslational modification of Elk-1 by small ubiquitin-related modifier (SUMO) serves as an important mechanism through which MMP-13 gene expression is regulated. We show that bFGF activates Elk-1 mainly through the ERK pathway and that increased phosphorylation of Elk-1 is accompanied by decreased conjugation of SUMO to Elk-1. Reporter gene assays reveal that phosphorylation renders Elk-1 competent for induction of MMP-13 gene transcription, while sumoylation has the opposite effect. Furthermore, we demonstrate that the SUMO-conjugase Ubc9 acts as a key mediator for Elk-1 sumoylation. Taken together, our results suggest that sumoylation antagonizes the phosphorylation-dependent transactivation capacity of Elk-1. This attenuates transcription of its downstream target gene MMP-13 to maintain the integrity of cartilage ECM homeostasis.
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Affiliation(s)
- Hee-Jeong Im
- Departments of Biochemistry
- Internal Medicine
- Section of Rheumatology, Orthopedic Surgery
- Rush University Medical Center, and Department of Bioengineering, University of Illinois at Chicago, IL USA
| | - Andrew D Sharrocks
- Faculty of Life Sciences, University of Manchester, Oxford Rd, Manchester, UK
| | - Xia Lin
- Michael E DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas, USA
| | | | | | - Andre J van Wijnen
- Department of Cell Biology, University of Massachusetts Medical School, Worcester, MA, USA
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7
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Abstract
The co-chaperone protein, BAG3, which belongs to the BAG protein family, has an established antiapoptotic function in different tumor cell lines. Here we demonstrated that treatment of the human neuroblastoma cell line, SK-N-MC, with fibroblast growth factor-2 (FGF-2) results in induction of BAG3 expression. Induction of BAG3 protein by FGF-2 occurs at the transcriptional level; it requires the extracellular regulated kinase1/2 pathway and is dependent on the activity of Egr-1 upon the BAG3 promoter. Targeted suppression of BAG3 by small-interfering RNA results in dysregulation of cell-cycle progression most notably at S and G(2) phases, which corroborates the decreased level of cyclin B1 expression. These observations suggest a new role for BAG3 in regulation of the cell cycle.
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8
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Ellman MB, An HS, Muddasani P, Im HJ. Biological impact of the fibroblast growth factor family on articular cartilage and intervertebral disc homeostasis. Gene 2008; 420:82-9. [PMID: 18565695 DOI: 10.1016/j.gene.2008.04.019] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Revised: 04/09/2008] [Accepted: 04/17/2008] [Indexed: 01/08/2023]
Abstract
Two members of the fibroblast growth factor (FGF) family, basic FGF (bFGF) and FGF-18, have been implicated in the regulation of articular and intervertebral disc (IVD) cartilage homeostasis. Studies on bFGF from a variety of species have yielded contradictory results with regards to its precise role in cartilage matrix synthesis and degradation. In contrast, FGF-18 is a well-known anabolic growth factor involved in chondrogenesis and articular cartilage repair. In this review, we examined the biological actions of bFGF and FGF-18 in articular and IVD cartilage, the specific cell surface receptors bound by each factor, and the unique signaling cascades and molecular pathways utilized to exert their biological effects. Evidence suggests that bFGF selectively activates FGF receptor 1 (FGFR1) to exert degradative effects in both human articular chondrocytes and IVD tissue via upregulation of matrix-degrading enzyme activity, inhibition of matrix production, and increased cell proliferation resulting in clustering of cells seen in arthritic states. FGF-18, on the other hand, most likely exerts anabolic effects in human articular chondrocytes by activating FGFR3, increasing matrix formation and cell differentiation while inhibiting cell proliferation, leading to dispersed cells surrounded by abundant matrix. The results from in vitro and in vivo studies suggest the potential usefulness of bFGF and FGFR1 antagonists, as well as FGF-18 and FGFR3 agonists, as potential therapies to prevent cartilage degeneration and/or promote cartilage regeneration and repair in the future.
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Affiliation(s)
- Michael B Ellman
- Department of Biochemistry, Rush University Medical Center, Chicago, IL 60612 USA
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Yang S, Nugent MA, Panchenko MP. EGF antagonizes TGF-beta-induced tropoelastin expression in lung fibroblasts via stabilization of Smad corepressor TGIF. Am J Physiol Lung Cell Mol Physiol 2008; 295:L143-51. [PMID: 18441095 DOI: 10.1152/ajplung.00289.2007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We previously reported that neutrophil elastase (NE) downregulates transforming growth factor-beta (TGF-beta)-maintained tropoelastin mRNA levels in lung fibroblasts through transactivation of the epidermal growth factor (EGF) receptor (EGFR)/Mek/Erk pathway, which is dependent on the NE-initiated release of soluble EGFR ligands. In the present study, we investigated the mechanism by which EGF downregulates tropoelastin expression. We found that EGF downregulates tropoelastin expression through inhibition of TGF-beta signaling. We show that EGF does not prevent the TGF-beta-induced nuclear accumulation of Smad2/3; rather, EGF stabilizes the short-lived Smad transcriptional corepressor TG-interacting factor (TGIF) via EGFR/Mek/Erk-mediated phosphorylation of TGIF. Elevation of TGIF levels, either by TGIF overexpression or prevention of TGIF degradation, is sufficient to inhibit TGF-beta-induced tropoelastin expression. Moreover, TGIF is essential for EGF-mediated downregulation of tropoelastin expression, inasmuch as small interfering RNA knockdown of TGIF blocked EGF-induced downregulation of tropoelastin. Finally, we demonstrated that NE treatment, which releases EGF-like growth factors, causes stabilization of TGIF through the EGFR/Mek/Erk pathway. These results suggest that EGFR/Mek/Erk signaling specifically antagonizes the proelastogenic action of TGF-beta in lung fibroblasts by stabilizing the Smad transcriptional corepressor TGIF.
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Affiliation(s)
- Shenghong Yang
- Department of Biochemistry, Boston University School of Medicine, 715 Albany St, Boston, Massachusetts 02118, USA
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Im HJ, Li X, Muddasani P, Kim GH, Davis F, Rangan J, Forsyth CB, Ellman M, Thonar EJMA. Basic fibroblast growth factor accelerates matrix degradation via a neuro-endocrine pathway in human adult articular chondrocytes. J Cell Physiol 2008; 215:452-63. [PMID: 17960584 DOI: 10.1002/jcp.21317] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Pain-related neuropeptides released from synovial fibroblasts, such as substance P, have been implicated in joint destruction. Substance P-induced inflammatory processes are mediated via signaling through a G-protein-coupled receptor, that is, neurokinin-1 tachykinin receptor (NK(1)-R). We determined the pathophysiological link between substance P and its receptor in human adult articular cartilage homeostasis. We further examined if catabolic growth factors such as basic fibroblast growth factor (bFGF or FGF-2) or IL-1beta accelerate matrix degradation via a neural pathway upregulation of substance P and NK(1)-R. We show here that substance P stimulates the production of cartilage-degrading enzymes, such as matrix metalloproteinase-13 (MMP-13), and suppresses proteoglycan deposition in human adult articular chondrocytes via NK(1)-R. Furthermore, we have demonstrated that substance P negates proteoglycan stimulation promoted by bone morphogenetic protein-7, suggesting the dual role of substance P as both a pro-catabolic and anti-anabolic mediator of cartilage homeostasis. We report that bFGF-mediated stimulation of substance P and its receptor NK(1)-R is, in part, through an IL-1beta-dependent pathway.
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Affiliation(s)
- Hee-Jeong Im
- Department of Biochemistry, Rush University Medical Center, Cohn Research BD, Chicago, Illinois 60612, USA.
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Im HJ, Muddasani P, Natarajan V, Schmid TM, Block JA, Davis F, van Wijnen AJ, Loeser RF. Basic fibroblast growth factor stimulates matrix metalloproteinase-13 via the molecular cross-talk between the mitogen-activated protein kinases and protein kinase Cdelta pathways in human adult articular chondrocytes. J Biol Chem 2007; 282:11110-21. [PMID: 17311929 PMCID: PMC2895271 DOI: 10.1074/jbc.m609040200] [Citation(s) in RCA: 141] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Excessive release of basic fibroblast growth factor (bFGF) during loading and/or injury of the cartilage matrix may contribute to the onset or progression of osteoarthritis. This pathological role may be related to the ability of bFGF to decrease proteoglycan synthesis and to antagonize the activity of anabolic growth factors in cartilage such as insulin-like growth factor-1 and bone morphogenetic protein 7 (BMP7 or OP-1). Matrix metalloproteinase-13 (MMP-13), a catabolic cartilage-degrading enzyme, is dramatically up-regulated by inflammatory cytokines or by fibronectin fragments in articular chondrocytes. In this study, we investigated MMP-13 production by bFGF using human articular chondrocytes. Endogenous concentration of bFGF in synovial fluids collected from arthritis patients and asymptomatic subjects showed a good linear correlation with the endogenous levels of MMP-13. bFGF stimulation of MMP-13 was mediated at the transcriptional level and, at least in part, by stimulation of interleukin-1 production. Also, our findings suggest that bFGF stimulation of MMP-13 required the activation of multiple MAPKs (ERK, p38, and JNK) by bFGF, and more importantly, bFGF activation of protein kinase C (PKC) delta played a key role in the MMP-13 stimulation. Indeed, PKCdelta is the only isoform associated with MMP-13 stimulation among the PKC isoforms tested. PKCdelta controls the bFGF response by regulating multiple MAPK pathways. Our results suggest that PKCdelta activation is a principal rate-limiting event in the bFGF-dependent stimulation of MMP-13 in human adult articular chondrocytes. We propose that deregulation of cross-talk between MAPK and PKCdelta signaling may contribute to the etiology of osteoarthritis in human patients.
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Affiliation(s)
- Hee-Jeong Im
- Department of Biochemistry, Rush University Medical Center, Chicago, Illinois 60612, USA.
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12
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Intensity-based hierarchical Bayes method improves testing for differentially expressed genes in microarray experiments. BMC Bioinformatics 2006; 7:538. [PMID: 17177995 PMCID: PMC1781470 DOI: 10.1186/1471-2105-7-538] [Citation(s) in RCA: 201] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2006] [Accepted: 12/19/2006] [Indexed: 01/11/2023] Open
Abstract
Background The small sample sizes often used for microarray experiments result in poor estimates of variance if each gene is considered independently. Yet accurately estimating variability of gene expression measurements in microarray experiments is essential for correctly identifying differentially expressed genes. Several recently developed methods for testing differential expression of genes utilize hierarchical Bayesian models to "pool" information from multiple genes. We have developed a statistical testing procedure that further improves upon current methods by incorporating the well-documented relationship between the absolute gene expression level and the variance of gene expression measurements into the general empirical Bayes framework. Results We present a novel Bayesian moderated-T, which we show to perform favorably in simulations, with two real, dual-channel microarray experiments and in two controlled single-channel experiments. In simulations, the new method achieved greater power while correctly estimating the true proportion of false positives, and in the analysis of two publicly-available "spike-in" experiments, the new method performed favorably compared to all tested alternatives. We also applied our method to two experimental datasets and discuss the additional biological insights as revealed by our method in contrast to the others. The R-source code for implementing our algorithm is freely available at . Conclusion We use a Bayesian hierarchical normal model to define a novel Intensity-Based Moderated T-statistic (IBMT). The method is completely data-dependent using empirical Bayes philosophy to estimate hyperparameters, and thus does not require specification of any free parameters. IBMT has the strength of balancing two important factors in the analysis of microarray data: the degree of independence of variances relative to the degree of identity (i.e. t-tests vs. equal variance assumption), and the relationship between variance and signal intensity. When this variance-intensity relationship is weak or does not exist, IBMT reduces to a previously described moderated t-statistic. Furthermore, our method may be directly applied to any array platform and experimental design. Together, these properties show IBMT to be a valuable option in the analysis of virtually any microarray experiment.
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Pierce RA, Moore CH, Arikan MC. Positive transcriptional regulatory element located within exon 1 of elastin gene. Am J Physiol Lung Cell Mol Physiol 2006; 291:L391-9. [PMID: 16899711 DOI: 10.1152/ajplung.00441.2004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Elastin gene transcription is cell type specific and developmentally regulated, but the promoter often exhibits relatively weak activity in transient transfections of cells that express elastin at high levels. To search for positive-acting regulatory sequences, we isolated genomic clones spanning the mouse elastin gene and extensive 5'- and 3'-flanking regions. Restriction fragments of potential regulatory regions were ligated 5' or 3' relative to the active promoter to test for enhancer activity in transient transfections of fetal rat lung fibroblasts, which express elastin at high levels, and distal lung epithelial cells, which do not express detectable elastin. Fragments of intron 1 did not exhibit significant enhancer activity. Inclusion of the 84-bp exon 1 and adjacent 5'-untranslated region increased activity of the elastin promoter approximately sixfold compared with parental constructs. Transfections with constructs of varying promoter length showed that as little as 40 bp of the 5' end of exon 1 confers enhanced activity in elastin-expressing rat lung fibroblasts, but these constructs had variable activity in lung epithelial cell lines. This region, localized between the transcription start site and extending into exon 1, binds Sp1 in nuclear extracts from elastin-expressing cells. These studies indicate a role for the 5' end of the first exon of the elastin gene in regulating strong transcriptional activity in elastogenic cells.
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Affiliation(s)
- Richard A Pierce
- Division of Pulmonary Medicine, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA.
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14
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Qi J, Chi L, Maloney M, Yang X, Bynum D, Banes AJ. Interleukin-1β Increases Elasticity of Human Bioartificial Tendons. ACTA ACUST UNITED AC 2006; 12:2913-25. [PMID: 17518659 DOI: 10.1089/ten.2006.12.2913] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Stiffness is an important mechanical property of connective tissues, especially for tissues subjected to cyclic strain in vivo, such as tendons. Therefore, modulation of material properties of native or engineered tissues is an important consideration for tissue repair. Interleukin 1-beta (IL-1beta) is a cytokine most often associated in connective tissues with induction of matrix metalloproteinases and matrix destruction. However, IL-1beta may also be involved in constructive remodeling and confer a cell survival value to tenocytes. In this study, we investigated the effects of IL-1beta on the properties of human tenocyte-populated bioartificial tendons (BATs) fabricated in a novel three-dimensional (3D) culture system. IL-1beta treatment reduced the ultimate tensile strength and elastic modulus of BATs and increased the maximum strain. IL-1beta at low doses (1, 10 pM) upregulated elastin expression and at a high dose (100 pM) downregulated type I collagen expression. Matrix metalloproteinases, which are involved in matrix remodeling, were also upregulated by IL-1beta. The increased elasticity prevented BATs from rupture caused by applied strain. The results in this study suggest that IL-1beta may act as a defense/survival factor in response to applied mechanical loading. The balance between cell intrinsic strain and external matrix strain is important for maintaining the integrity of tendons.
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Affiliation(s)
- Jie Qi
- Flexcell International Corp., Hillsborough, North Carolina, USA
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15
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Serlin DM, Kuang PP, Subramanian M, O'Regan A, Li X, Berman JS, Goldstein RH. Interleukin-1beta induces osteopontin expression in pulmonary fibroblasts. J Cell Biochem 2006; 97:519-29. [PMID: 16211580 DOI: 10.1002/jcb.20661] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Osteopontin is a multifunctional matricellular protein identified as one of the most upregulated genes in pulmonary fibrosis. Experimental animal models have identified early pro-fibrotic cytokines as essential to the pathogenesis of inflammation-induced pulmonary fibrosis. However, the principal sources of osteopontin in the fibroproliferative lung, and the factors responsible for its induction, have not been fully defined. We isolated primary rat lung fibroblasts in culture to examine the expression and regulation of lung fibroblast-derived osteopontin. Our results demonstrate a potent and dramatic increase in osteopontin expression induced by interleukin-1beta (IL-1beta), whereas tumor necrosis factor-alpha, transforming growth factor-beta, and angiotensin II had minimal effect. Stimulation with IL-1beta resulted in the secretion of soluble osteopontin protein. We found that osteopontin expression by IL-1beta was regulated via signaling primarily through the mitogen-activated protein kinase member ERK1/2, partially by p38 MAPK, but not at all by JNK. Finally, the mechanism of IL-1beta increase in osteopontin mRNA requires de novo transcription and translation. In conclusion, we find that osteopontin is expressed by primary lung fibroblasts and is potently upregulated by the early inflammatory and pro-fibrotic cytokine IL-1beta. Activated fibroblasts may be a significant source of osteopontin production during lung fibrogenesis.
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Affiliation(s)
- David M Serlin
- Department of Medicine, Pulmonary Center, Boston University School of Medicine, 715 Albany Street R304, Boston, MA 02118, USA.
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16
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Liu J, Rich CB, Buczek-Thomas JA, Nugent MA, Panchenko MP, Foster JA. Heparin-binding EGF-like growth factor regulates elastin and FGF-2 expression in pulmonary fibroblasts. Am J Physiol Lung Cell Mol Physiol 2003; 285:L1106-15. [PMID: 12882762 DOI: 10.1152/ajplung.00180.2003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Elastase degradation of elastin within alveolar walls is an important event in the development of pulmonary emphysema. In addition to elastolytic activities, elastases release growth factors from extracellular matrices and interstitial cell surfaces that can regulate elastogenesis and other cellular responses. In the present study, we demonstrate that brief treatment of matrix-laden rat pulmonary fibroblast cultures with pancreatic elastase results in the release of soluble heparin-binding epidermal growth factor-like growth factor (HB-EGF) concomitant with a decrease in HB-EGF binding to both heparan sulfate proteoglycan and receptor sites on the cells. In undigested, matrix-laden fibroblasts, HB-EGF significantly downregulates elastin mRNA via activation of epidermal growth factor receptor. Results from nuclear run-on analyses show that HB-EGF downregulates elastin mRNA via transcriptional suppression. HBEGF treatment stimulates MAP or ERK kinase (MEK)-dependent ERK1/2 phosphorylation and leads to nuclear accumulation of Fra-1. Blocking ERK1/2 activation by MEK1/2 inhibitors (PD-98059 or U-0126) diminishes HB-EGF-induced Fra-1 accumulation and subsequent downregulation of elastin mRNA. Coaddition of two elastase-released growth factors, HB-EGF and FGF-2, results in an additive inhibitory effect on elastin mRNA levels. Furthermore, HB-EGF addition to pulmonary fibroblasts increases FGF-2 mRNA and protein levels. These data suggest that HB-EGF and FGF-2 act in concert to regulate the synthesis of elastin in injury/repair situations.
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Affiliation(s)
- Jianghuai Liu
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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17
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Rich CB, Carreras I, Lucey EC, Jaworski JA, Buczek-Thomas JA, Nugent MA, Stone P, Foster JA. Transcriptional regulation of pulmonary elastin gene expression in elastase-induced injury. Am J Physiol Lung Cell Mol Physiol 2003; 285:L354-62. [PMID: 12679320 DOI: 10.1152/ajplung.00026.2003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Previously we have shown that treatment of confluent, pulmonary fibroblast cultures with elastase results in upregulation of elastin mRNA and protein levels. In the present study we focused on determining the level at which elastin expression is upregulated after elastase exposure. We examined as models for this investigation elastin gene expression in primary pulmonary fibroblast cells during the transition from subconfluent to confluent cultures and in confluent, matrix-laden cultures treated briefly with elastase. In addition, we extended our studies to mice that were given an intratracheal dose of elastase; the effects on lung elastin mRNA and elastin promoter activity levels were measured and compared with results from in vitro cell models. The results demonstrate that upregulation of elastin gene expression during the transition of subconfluent to confluent cultures and after elastase injury is associated with an increase in the level of transcription both in vitro and in vivo. Furthermore, intratracheal administration of elastase to transgenic mice illustrates that the increased levels of elastin mRNA are accompanied by increased activity of the elastin gene promoter in cells spatially positioned near major sites of tissue injury.
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Affiliation(s)
- Celeste B Rich
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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18
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Abstract
In the airways of patients with cystic fibrosis, repeated cycles of infection and inflammation are responsible for bronchial wall thickening, a major determinant of loss of FEV(1) and progressive damage to the small and large airways. Proteolytic degradation of elastin, collagen and fibronectin fibrils in the tissue matrix leads to the loss of normal tissue architecture and the development of bronchiectasis, the most commonly observed morphological change on high-resolution computed tomography examination. We have reviewed the evidence for increased expression of growth factors (TGF, HGF, FGF, EGF, VEGF) and activation of tissue repair processes in cystic fibrosis. Significantly higher concentrations of the growth factors compared with normal do not appear to prevent or reverse structural remodelling in the airways. The reasons why this process appears to be ineffective are discussed and we speculate on alternative strategies that might have a significant impact on the observed structural changes.
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Affiliation(s)
- Janis Shute
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DT, UK.
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19
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Reddy SPM, Mossman BT. Role and regulation of activator protein-1 in toxicant-induced responses of the lung. Am J Physiol Lung Cell Mol Physiol 2002; 283:L1161-78. [PMID: 12424143 DOI: 10.1152/ajplung.00140.2002] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Aberrant cell proliferation and differentiation after toxic injury to airway epithelium can lead to the development of various lung diseases including cancer. The activator protein-1 (AP-1) transcription factor, composed of mainly Jun-Jun and Jun-Fos protein dimers, acts as an environmental biosensor to various external toxic stimuli and regulates gene expression involved in various biological processes. Gene disruption studies indicate that the AP-1 family members c-jun, junB, and fra1 are essential for embryonic development, whereas junD, c-fos, and fosB are required for normal postnatal growth. However, broad or target-specific transgenic overexpression of the some of these proteins gives very distinct phenotype(s), including tumor formation. This implies that, although they are required for normal cellular processes, their abnormal activation after toxic injury can lead to the pathogenesis of the lung disease. Consistent with this view, various environmental toxicants and carcinogens differentially regulate Jun and Fos expression in cells of the lung both in vivo and in vitro. Moreover, Jun and Fos proteins distinctly bind to the promoter regions of a wide variety of genes to differentially regulate their expression in epithelial injury, repair, and differentiation. Importantly, lung tumors induced by various carcinogens display a sustained expression of certain AP-1 family members. Therefore a better understanding of the mechanisms of regulation and functional role(s), as well as identification of target genes of members of the AP-1 family in airway epithelial cells, will provide additional insight into toxicant-induced lung diseases. These studies might offer a unique opportunity to use AP-1 family members and transactivation as potential diagnostic markers or drug targets for early detection and/or prevention of various lung diseases.
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Affiliation(s)
- Sekhar P M Reddy
- Department of Environmental Health Sciences and Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University, Baltimore, Maryland 21205, USA.
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20
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Carreras I, Rich CB, Panchenko MP, Foster JA. Basic fibroblast growth factor decreases elastin gene transcription in aortic smooth muscle cells. J Cell Biochem 2002; 85:592-600. [PMID: 11967999 DOI: 10.1002/jcb.10163] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The extracellular matrix (ECM) protein elastin plays an essential role in the cardiovascular system by imparting elasticity to blood vessel wall. In this study, we examined the effect of basic fibroblast growth factor (bFGF) on the expression of elastin in aortic smooth muscle cells (SMC) to gain insight into events associated with cardiovascular diseases. The results show that bFGF treatment of SMC causes a significant decrease in elastin mRNA and secreted tropoelastin levels. Nuclear run-on analyses demonstrate that the downregulation is due to a decrease in the level of elastin gene transcription. Transient transfections of SMC with wild-type and mutated elastin gene promoter/chloramphenicol acetyl transferase (CAT) constructs show that a previously identified activator protein-1-cAMP response element (AP1/CRE) (-564 to -558-bp) within the elastin promoter mediates the bFGF-dependent downregulation of elastin gene transcription in SMC. Addition of bFGF to SMC activates the extracellular signal-regulated kinases 1/2 (ERK1/2) resulting in their translocation into the nucleus and subsequent induction of Fra-1. The addition of PD-98059, an inhibitor of ERK1/2 kinase, abrogates the bFGF-dependent decrease of elastin mRNA in SMC. The described inhibitory effect of bFGF on elastin gene expression in SMC may significantly contribute to the inefficient repair of elastin in early stages of vascular wall injury.
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MESH Headings
- Animals
- Aorta/cytology
- Aorta/metabolism
- Cells, Cultured
- Cyclic AMP/metabolism
- Down-Regulation/drug effects
- Elastin/drug effects
- Elastin/genetics
- Elastin/metabolism
- Enzyme Inhibitors/pharmacology
- Fibroblast Growth Factor 2/metabolism
- Fibroblast Growth Factor 2/pharmacology
- Flavonoids/pharmacology
- Mitogen-Activated Protein Kinase 1/antagonists & inhibitors
- Mitogen-Activated Protein Kinase 1/drug effects
- Mitogen-Activated Protein Kinase 1/metabolism
- Mitogen-Activated Protein Kinase 3
- Mitogen-Activated Protein Kinases/antagonists & inhibitors
- Mitogen-Activated Protein Kinases/drug effects
- Mitogen-Activated Protein Kinases/metabolism
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Promoter Regions, Genetic/physiology
- Proto-Oncogene Proteins c-fos/drug effects
- Proto-Oncogene Proteins c-fos/metabolism
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Response Elements/physiology
- Signal Transduction
- Transcription Factor AP-1/metabolism
- Transcription, Genetic/drug effects
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Affiliation(s)
- Isabel Carreras
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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21
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Stenmark KR. Cell-, age-, and phenotype-dependent differences in the control of gene expression. Am J Physiol Lung Cell Mol Physiol 2001; 281:L762-5. [PMID: 11557579 DOI: 10.1152/ajplung.2001.281.4.l762] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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