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Borza CM, Bolas G, Pozzi A. Genetic and pharmacological tools to study the role of discoidin domain receptors in kidney disease. Front Pharmacol 2022; 13:1001122. [PMID: 36249782 PMCID: PMC9554349 DOI: 10.3389/fphar.2022.1001122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 08/29/2022] [Indexed: 11/13/2022] Open
Abstract
Following injury the kidney undergoes a repair process, which results in replacement of the injured tissue with little evidence of damage. However, repetitive injuries or inability of the kidney to stop the repair process result in abnormal deposition of extracellular matrix (ECM) components leading to fibrosis and organ dysfunction. The synthesis/degradation of ECM components is finely regulated by several factors, including discoidin domain receptors (DDRs). These are receptor tyrosine kinases that are activated by collagens. Upon activation, DDRs control several cell functions that, when exacerbated, contribute to kidney injury and fibrosis. DDRs are undetectable in healthy kidney, but become rapidly upregulated in several kidney fibrotic conditions, thus making them attractive anti-fibrotic targets. DDRs contribute to kidney injury and fibrosis by promoting apoptosis of injured kidney cells, stimulating the production of pro-inflammatory cytokines, and regulating the production of ECM components. They achieve these effects by activating canonical intracellular molecules or by directly interacting with nuclear chromatin and promoting the transcription of pro-fibrotic genes. The goal of this review is to highlight canonical and non-canonical mechanisms whereby DDRs contribute to kidney injury/fibrosis. This review will summarize key findings obtained using cells and mice lacking DDRs and it will discuss the discovery and development of targeted DDR small molecule- and antisense-based inhibitors. Understanding the molecular mechanisms whereby DDRs control kidney injury and fibrosis might enable us to not only develop more selective and potent inhibitors, but to also determine when DDR inhibition needs to be achieved to prevent and/or halt the development of kidney fibrosis.
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Affiliation(s)
- Corina M. Borza
- Department of Medicine (Division of Nephrology), Vanderbilt University School of Medicine, Nashville, TN, United States
| | - Gema Bolas
- Department of Medicine (Division of Nephrology), Vanderbilt University School of Medicine, Nashville, TN, United States
| | - Ambra Pozzi
- Department of Medicine (Division of Nephrology), Vanderbilt University School of Medicine, Nashville, TN, United States
- Veterans Affairs Hospitals, Nashville, TN, United States
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2
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Borza CM, Bolas G, Zhang X, Browning Monroe MB, Zhang MZ, Meiler J, Skwark MJ, Harris RC, Lapierre LA, Goldenring JR, Hook M, Rivera J, Brown KL, Leitinger B, Tyska MJ, Moser M, Böttcher RT, Zent R, Pozzi A. The Collagen Receptor Discoidin Domain Receptor 1b Enhances Integrin β1-Mediated Cell Migration by Interacting With Talin and Promoting Rac1 Activation. Front Cell Dev Biol 2022; 10:836797. [PMID: 35309920 PMCID: PMC8928223 DOI: 10.3389/fcell.2022.836797] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 02/04/2022] [Indexed: 01/17/2023] Open
Abstract
Integrins and discoidin domain receptors (DDRs) 1 and 2 promote cell adhesion and migration on both fibrillar and non fibrillar collagens. Collagen I contains DDR and integrin selective binding motifs; however, the relative contribution of these two receptors in regulating cell migration is unclear. DDR1 has five isoforms (DDR1a-e), with most cells expressing the DDR1a and DDR1b isoforms. We show that human embryonic kidney 293 cells expressing DDR1b migrate more than DDR1a expressing cells on DDR selective substrata as well as on collagen I in vitro. In addition, DDR1b expressing cells show increased lung colonization after tail vein injection in nude mice. DDR1a and DDR1b differ from each other by an extra 37 amino acids in the DDR1b cytoplasmic domain. Interestingly, these 37 amino acids contain an NPxY motif which is a central control module within the cytoplasmic domain of β integrins and acts by binding scaffold proteins, including talin. Using purified recombinant DDR1 cytoplasmic tail proteins, we show that DDR1b directly binds talin with higher affinity than DDR1a. In cells, DDR1b, but not DDR1a, colocalizes with talin and integrin β1 to focal adhesions and enhances integrin β1-mediated cell migration. Moreover, we show that DDR1b promotes cell migration by enhancing Rac1 activation. Mechanistically DDR1b interacts with the GTPase-activating protein (GAP) Breakpoint cluster region protein (BCR) thus reducing its GAP activity and enhancing Rac activation. Our study identifies DDR1b as a major driver of cell migration and talin and BCR as key players in the interplay between integrins and DDR1b in regulating cell migration.
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Affiliation(s)
- Corina M. Borza
- Department of Medicine, Division of Nephrology, Vanderbilt University, Nashville, TN, United States
| | - Gema Bolas
- Department of Medicine, Division of Nephrology, Vanderbilt University, Nashville, TN, United States
| | - Xiuqi Zhang
- Department of Medicine, Division of Nephrology, Vanderbilt University, Nashville, TN, United States
| | | | - Ming-Zhi Zhang
- Department of Medicine, Division of Nephrology, Vanderbilt University, Nashville, TN, United States
| | - Jens Meiler
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
- Leipzig University Medical School, Institute for Drug Discovery, Leipzig, Germany
| | - Marcin J. Skwark
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
| | - Raymond C. Harris
- Department of Medicine, Division of Nephrology, Vanderbilt University, Nashville, TN, United States
| | - Lynne A. Lapierre
- Department of Surgery, Vanderbilt University, Nashville, TN, United States
- Veterans Affairs Hospital, Nashville, TN, United States
| | - James R. Goldenring
- Department of Surgery, Vanderbilt University, Nashville, TN, United States
- Veterans Affairs Hospital, Nashville, TN, United States
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, United States
| | - Magnus Hook
- Texas A&M Health Science Center Institute of Biosciences and Technology, Houston, TX, United States
| | - Jose Rivera
- Texas A&M Health Science Center Institute of Biosciences and Technology, Houston, TX, United States
| | - Kyle L. Brown
- Department of Medicine, Division of Nephrology, Vanderbilt University, Nashville, TN, United States
| | - Birgit Leitinger
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Matthew J. Tyska
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, United States
| | - Markus Moser
- Department for Molecular Medicine, Max-Planck-Institute of Biochemistry, Martinsried, Germany
| | - Ralph T. Böttcher
- Department for Molecular Medicine, Max-Planck-Institute of Biochemistry, Martinsried, Germany
| | - Roy Zent
- Department of Medicine, Division of Nephrology, Vanderbilt University, Nashville, TN, United States
- Veterans Affairs Hospital, Nashville, TN, United States
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, United States
| | - Ambra Pozzi
- Department of Medicine, Division of Nephrology, Vanderbilt University, Nashville, TN, United States
- Veterans Affairs Hospital, Nashville, TN, United States
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Borza CM, Bolas G, Bock F, Zhang X, Akabogu FC, Zhang MZ, de Caestecker M, Yang M, Yang H, Lee E, Gewin L, Fogo AB, McDonald WH, Zent R, Pozzi A. DDR1 contributes to kidney inflammation and fibrosis by promoting the phosphorylation of BCR and STAT3. JCI Insight 2021; 7:150887. [PMID: 34941574 PMCID: PMC8855801 DOI: 10.1172/jci.insight.150887] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 12/21/2021] [Indexed: 11/25/2022] Open
Abstract
Discoidin domain receptor 1 (DDR1), a receptor tyrosine kinase activated by collagen, contributes to chronic kidney disease. However, its role in acute kidney injury and subsequent development of kidney fibrosis is not clear. Thus, we performed a model of severe ischemia/reperfusion-induced acute kidney injury that progressed to kidney fibrosis in WT and Ddr1-null mice. We showed that Ddr1-null mice had reduced acute tubular injury, inflammation, and tubulointerstitial fibrosis with overall decreased renal monocyte chemoattractant protein (MCP-1) levels and STAT3 activation. We identified breakpoint cluster region (BCR) protein as a phosphorylated target of DDR1 that controls MCP-1 production in renal proximal tubule epithelial cells. DDR1-induced BCR phosphorylation or BCR downregulation increased MCP-1 secretion, suggesting that BCR negatively regulates the levels of MCP-1. Mechanistically, phosphorylation or downregulation of BCR increased β-catenin activity and in turn MCP-1 production. Finally, we showed that DDR1-mediated STAT3 activation was required to stimulate the secretion of TGF-β. Thus, DDR1 contributes to acute and chronic kidney injury by regulating BCR and STAT3 phosphorylation and in turn the production of MCP-1 and TGF-β. These findings identify DDR1 an attractive therapeutic target for ameliorating both proinflammatory and profibrotic signaling in kidney disease.
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Affiliation(s)
- Corina M. Borza
- Department of Medicine, Division of Nephrology and Hypertension, and
| | - Gema Bolas
- Department of Medicine, Division of Nephrology and Hypertension, and
| | - Fabian Bock
- Department of Medicine, Division of Nephrology and Hypertension, and
| | - Xiuqi Zhang
- Department of Medicine, Division of Nephrology and Hypertension, and
| | - Favour C. Akabogu
- Department of Medicine, Division of Nephrology and Hypertension, and
| | - Ming-Zhi Zhang
- Department of Medicine, Division of Nephrology and Hypertension, and
| | | | - Min Yang
- Department of Medicine, Division of Nephrology and Hypertension, and
| | - Haichun Yang
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Ethan Lee
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Leslie Gewin
- Division of Nephrology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Agnes B. Fogo
- Department of Medicine, Division of Nephrology and Hypertension, and
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - W. Hayes McDonald
- Proteomics Laboratory, Mass Spectrometry Research Center, Vanderbilt University, Nashville, Tennessee, USA
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Roy Zent
- Department of Medicine, Division of Nephrology and Hypertension, and
- Department of Veterans Affairs, Nashville, Nashville, Tennessee, USA
| | - Ambra Pozzi
- Department of Medicine, Division of Nephrology and Hypertension, and
- Department of Veterans Affairs, Nashville, Nashville, Tennessee, USA
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Jeffries DE, Borza CM, Blobaum AL, Pozzi A, Lindsley CW. Discovery of VU6015929: A Selective Discoidin Domain Receptor 1/2 (DDR1/2) Inhibitor to Explore the Role of DDR1 in Antifibrotic Therapy. ACS Med Chem Lett 2020; 11:29-33. [PMID: 31938459 DOI: 10.1021/acsmedchemlett.9b00382] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 11/25/2019] [Indexed: 01/07/2023] Open
Abstract
Herein, we report the discovery of a potent and selective dual DDR1/2 inhibitor, 7e (VU6015929), displaying low cytotoxicity, good kinome selectivity, and possessing an acceptable in vitro DMPK profile with good rodent in vivo pharmacokinetics. VU6015929 potently blocks collagen-induced DDR1 activation and collagen-IV production, suggesting DDR1 inhibition as an exciting target for antifibrotic therapy.
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Affiliation(s)
- Daniel E. Jeffries
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Corina M. Borza
- Department of Medicine, Division of Nephrology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Anna L. Blobaum
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | - Ambra Pozzi
- Department of Medicine, Division of Nephrology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Veterans Affairs Medical Center, Nashville, Nashville, Tennessee 37232, United States
| | - Craig W. Lindsley
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37232, United States
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
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5
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Chiusa M, Hu W, Liao HJ, Su Y, Borza CM, de Caestecker MP, Skrypnyk NI, Fogo AB, Pedchenko V, Li X, Zhang MZ, Hudson BG, Basak T, Vanacore RM, Zent R, Pozzi A. The Extracellular Matrix Receptor Discoidin Domain Receptor 1 Regulates Collagen Transcription by Translocating to the Nucleus. J Am Soc Nephrol 2019; 30:1605-1624. [PMID: 31383731 PMCID: PMC6727269 DOI: 10.1681/asn.2018111160] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Accepted: 05/20/2019] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND The discoidin domain receptor 1 (DDR1) is activated by collagens, upregulated in injured and fibrotic kidneys, and contributes to fibrosis by regulating extracellular matrix production, but how DDR1 controls fibrosis is poorly understood. DDR1 is a receptor tyrosine kinase (RTK). RTKs can translocate to the nucleus via a nuclear localization sequence (NLS) present on the receptor itself or a ligand it is bound to. In the nucleus, RTKs regulate gene expression by binding chromatin directly or by interacting with transcription factors. METHODS To determine whether DDR1 translocates to the nucleus and whether this event is mediated by collagen-induced DDR1 activation, we generated renal cells expressing wild-type or mutant forms of DDR1 no longer able to bind collagen. Then, we determined the location of the DDR1 upon collagen stimulation. Using both biochemical assays and immunofluorescence, we analyzed the steps involved in DDR1 nuclear translocation. RESULTS We show that although DDR1 and its natural ligand, collagen, lack an NLS, DDR1 is present in the nucleus of injured human and mouse kidney proximal tubules. We show that DDR1 nuclear translocation requires collagen-mediated receptor activation and interaction of DDR1 with SEC61B, a component of the Sec61 translocon, and nonmuscle myosin IIA and β-actin. Once in the nucleus, DDR1 binds to chromatin to increase the transcription of collagen IV, a major collagen upregulated in fibrosis. CONCLUSIONS These findings reveal a novel mechanism whereby activated DDR1 translates to the nucleus to regulate synthesis of profibrotic molecules.
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Affiliation(s)
- Manuel Chiusa
- Division of Nephrology and Hypertension, Department of Medicine, and
| | - Wen Hu
- Division of Nephrology and Hypertension, Department of Medicine, and
| | - Hong-Jun Liao
- Division of Nephrology and Hypertension, Department of Medicine, and
| | - Yan Su
- Division of Nephrology and Hypertension, Department of Medicine, and
| | - Corina M Borza
- Division of Nephrology and Hypertension, Department of Medicine, and
| | | | | | - Agnes B Fogo
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee; and
| | - Vadim Pedchenko
- Division of Nephrology and Hypertension, Department of Medicine, and
| | - Xiyue Li
- Division of Nephrology and Hypertension, Department of Medicine, and
| | - Ming-Zhi Zhang
- Division of Nephrology and Hypertension, Department of Medicine, and
| | - Billy G Hudson
- Division of Nephrology and Hypertension, Department of Medicine, and
| | - Trayambak Basak
- Division of Nephrology and Hypertension, Department of Medicine, and
| | | | - Roy Zent
- Division of Nephrology and Hypertension, Department of Medicine, and
- Department of Veterans Affairs, Nashville, Tennessee
| | - Ambra Pozzi
- Division of Nephrology and Hypertension, Department of Medicine, and
- Department of Veterans Affairs, Nashville, Tennessee
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6
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Affiliation(s)
- Corina M Borza
- 1 Department of Medicine Vanderbilt University Medical Center Nashville, Tennessee
| | - Ambra Pozzi
- 2 Veterans Affairs Hospitals Nashville, Tennessee and
| | - Erin J Plosa
- 3 Department of Pediatrics Vanderbilt University Medical Center Nashville, Tennessee
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7
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Borza CM, Su Y, Tran TL, Yu L, Steyns N, Temple KJ, Skwark MJ, Meiler J, Lindsley CW, Hicks BR, Leitinger B, Zent R, Pozzi A. Discoidin domain receptor 1 kinase activity is required for regulating collagen IV synthesis. Matrix Biol 2017; 57-58:258-271. [PMID: 27915093 PMCID: PMC5329129 DOI: 10.1016/j.matbio.2016.11.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 11/21/2016] [Accepted: 11/22/2016] [Indexed: 01/29/2023]
Abstract
Discoidin domain receptor 1 (DDR1) is a receptor tyrosine kinase that binds to and is activated by collagens. DDR1 expression increases following kidney injury and accumulating evidence suggests that it contributes to the progression of injury. To this end, deletion of DDR1 is beneficial in ameliorating kidney injury induced by angiotensin infusion, unilateral ureteral obstruction, or nephrotoxic nephritis. Most of the beneficial effects observed in the DDR1-null mice are attributed to reduced inflammatory cell infiltration to the site of injury, suggesting that DDR1 plays a pro-inflammatory effect. The goal of this study was to determine whether, in addition to its pro-inflammatory effect, DDR1 plays a deleterious effect in kidney injury by directly regulating extracellular matrix production. We show that DDR1-null mice have reduced deposition of glomerular collagens I and IV as well as decreased proteinuria following the partial renal ablation model of kidney injury. Using mesangial cells isolated from DDR1-null mice, we show that these cells produce significantly less collagen compared to DDR1-null cells reconstituted with wild type DDR1. Moreover, mutagenesis analysis revealed that mutations in the collagen binding site or in the kinase domain significantly reduce DDR1-mediated collagen production. Finally, we provide evidence that blocking DDR1 kinase activity with an ATP-competitive small molecule inhibitor reduces collagen production. In conclusion, our studies indicate that the kinase activity of DDR1 plays a key role in DDR1-induced collagen synthesis and suggest that blocking collagen-mediated DDR1 activation may be beneficial in fibrotic diseases.
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Affiliation(s)
- Corina M Borza
- Department of Medicine (Division of Nephrology), Vanderbilt University, Nashville, TN, United States
| | - Yan Su
- Department of Medicine (Division of Nephrology), Vanderbilt University, Nashville, TN, United States
| | - Truc-Linh Tran
- Department of Medicine (Division of Nephrology), Vanderbilt University, Nashville, TN, United States
| | - Ling Yu
- Department of Medicine (Division of Nephrology), Vanderbilt University, Nashville, TN, United States
| | - Nick Steyns
- Department Chemistry, Pharmacology, Vanderbilt University, Nashville, TN, United States
| | - Kayla J Temple
- Department Chemistry, Pharmacology, Vanderbilt University, Nashville, TN, United States
| | - Marcin J Skwark
- Department Chemistry, Pharmacology, Vanderbilt University, Nashville, TN, United States
| | - Jens Meiler
- Department Chemistry, Pharmacology, Vanderbilt University, Nashville, TN, United States
| | - Craig W Lindsley
- Department Chemistry, Pharmacology, Vanderbilt University, Nashville, TN, United States
| | - Brennan R Hicks
- Department of Medicine (Division of Nephrology), Vanderbilt University, Nashville, TN, United States
| | - Birgit Leitinger
- National Heart and Lung Institute, Imperial College of London, London, UK
| | - Roy Zent
- Department of Medicine (Division of Nephrology), Vanderbilt University, Nashville, TN, United States; Cell and Developmental Biology, Vanderbilt University, Nashville, TN, United States; Veterans Affairs Hospitals, Nashville, TN, United States
| | - Ambra Pozzi
- Department of Medicine (Division of Nephrology), Vanderbilt University, Nashville, TN, United States; Veterans Affairs Hospitals, Nashville, TN, United States.
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8
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Kothiwale S, Borza CM, Lowe EW, Pozzi A, Meiler J. Discoidin domain receptor 1 (DDR1) kinase as target for structure-based drug discovery. Drug Discov Today 2015; 20:255-61. [PMID: 25284748 PMCID: PMC4336622 DOI: 10.1016/j.drudis.2014.09.025] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2014] [Revised: 08/08/2014] [Accepted: 09/26/2014] [Indexed: 11/18/2022]
Abstract
Discoidin domain receptor (DDR) 1 and 2 are transmembrane receptors that belong to the family of receptor tyrosine kinases (RTK). Upon collagen binding, DDRs transduce cellular signaling involved in various cell functions, including cell adhesion, proliferation, differentiation, migration, and matrix homeostasis. Altered DDR function resulting from either mutations or overexpression has been implicated in several types of disease, including atherosclerosis, inflammation, cancer, and tissue fibrosis. Several established inhibitors, such as imatinib, dasatinib, and nilotinib, originally developed as Abelson murine leukemia (Abl) kinase inhibitors, have been found to inhibit DDR kinase activity. As we review here, recent discoveries of novel inhibitors and their co-crystal structure with the DDR1 kinase domain have made structure-based drug discovery for DDR1 amenable.
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Affiliation(s)
| | - Corina M Borza
- Department of Medicine, Division of Nephrology, Vanderbilt University, Nashville, TN 37232, USA
| | - Edward W Lowe
- Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA
| | - Ambra Pozzi
- Department of Medicine, Division of Nephrology, Vanderbilt University, Nashville, TN 37232, USA; Department of Medicine, Veterans Affairs Hospital, Nashville, TN 37232, USA
| | - Jens Meiler
- Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA.
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Abstract
Cell-extracellular matrix (ECM) interactions are essential for tissue development, homeostasis, and response to injury. Basement membranes (BMs) are specialized ECMs that separate epithelial or endothelial cells from stromal components and interact with cells via cellular receptors, including integrins and discoidin domain receptors. Disruption of cell-BM interactions due to either injury or genetic defects in either the ECM components or cellular receptors often lead to irreversible tissue injury and loss of organ function. Animal models that lack specific BM components or receptors either globally or in selective tissues have been used to help with our understanding of the molecular mechanisms whereby cell-BM interactions regulate organ function in physiological and pathological conditions. We review recently published works on animal models that explore how cell-BM interactions regulate kidney homeostasis in both health and disease.
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Affiliation(s)
- Corina M. Borza
- Department of Medicine, Division of Nephrology, Vanderbilt University Medical Center, Nashville, TN, 37232
- Vanderbilt Center for Kidney Disease, Vanderbilt University Medical Center, Nashville, TN, 37232
| | - Xiwu Chen
- Department of Medicine, Division of Nephrology, Vanderbilt University Medical Center, Nashville, TN, 37232
| | - Roy Zent
- Department of Medicine, Division of Nephrology, Vanderbilt University Medical Center, Nashville, TN, 37232
- Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, TN, 37232
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN, 37232
- Vanderbilt Center for Kidney Disease, Vanderbilt University Medical Center, Nashville, TN, 37232
- Department of Medicine, Veterans Administration Hospital, Nashville, TN, 37232
| | - Ambra Pozzi
- Department of Medicine, Division of Nephrology, Vanderbilt University Medical Center, Nashville, TN, 37232
- Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, TN, 37232
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, 37232
- Vanderbilt Center for Kidney Disease, Vanderbilt University Medical Center, Nashville, TN, 37232
- Department of Medicine, Veterans Administration Hospital, Nashville, TN, 37232
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Borza CM, Su Y, Chen X, Yu L, Mont S, Chetyrkin S, Voziyan P, Hudson BG, Billings PC, Jo H, Bennett JS, Degrado WF, Eckes B, Zent R, Pozzi A. Inhibition of integrin α2β1 ameliorates glomerular injury. J Am Soc Nephrol 2012; 23:1027-38. [PMID: 22440900 DOI: 10.1681/asn.2011040367] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Mesangial cells and podocytes express integrins α1β1 and α2β1, which are the two major collagen receptors that regulate multiple cellular functions, including extracellular matrix homeostasis. Integrin α1β1 protects from glomerular injury by negatively regulating collagen production, but the role of integrin α2β1 in renal injury is unclear. Here, we subjected wild-type and integrin α2-null mice to injury with adriamycin or partial renal ablation. In both of these models, integrin α2-null mice developed significantly less proteinuria and glomerulosclerosis. In addition, selective pharmacological inhibition of integrin α2β1 significantly reduced adriamycin-induced proteinuria, glomerular injury, and collagen deposition in wild-type mice. This inhibitor significantly reduced collagen synthesis in wild-type, but not integrin α2-null, mesangial cells in vitro, demonstrating that its effects are integrin α2β1-dependent. Taken together, these results indicate that integrin α2β1 contributes to glomerular injury by positively regulating collagen synthesis and suggest that its inhibition may be a promising strategy to reduce glomerular injury and proteinuria.
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Affiliation(s)
- Corina M Borza
- Departments of Medicine and Cancer Biology, Division of Nephrology and Hypertension, Vanderbilt University, Medical Center North, Nashville, TN 37232, USA
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Abstract
Glomerulosclerosis is characterized by excessive deposition of extracellular matrix within the glomeruli of the kidney, glomerular cell death, and subsequent loss of functional glomeruli. While in physiological situations the levels of extracellular matrix components are kept constant by a tight balance between formation and degradation, in the case of injury that results in fibrosis there is increased matrix deposition relative to its breakdown. Multiple factors control matrix synthesis and degradation, thus contributing to the development of glomerulosclerosis. This review focuses primarily on the role of cell-matrix interactions, which play a critical role in governing glomerular cell cues in both healthy and diseased kidneys. Cell-extracellular matrix interactions are made possible by various cellular receptors including integrins, discoidin domain receptors, and dystroglycan. Upon binding to a selective extracellular matrix protein, these receptors activate intracellular signaling pathways that can either downregulate or upregulate matrix synthesis and deposition. This, together with the observation that changes in the expression levels of matrix receptors have been documented in glomerular disease, clearly emphasizes the contribution of cell-matrix interactions in glomerular injury. Understanding the molecular mechanisms whereby extracellular matrix receptors regulate matrix homeostasis in the course of glomerular injury is therefore critical for devising more effective therapies to treat and ideally prevent glomerulosclerosis.
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Affiliation(s)
- Corina M Borza
- Department of Medicine, Division of Nephrology, Vanderbilt University, Nashville, TN 37232, USA.
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12
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Borza CM, Chen X, Mathew S, Mont S, Sanders CR, Zent R, Pozzi A. Integrin {alpha}1{beta}1 promotes caveolin-1 dephosphorylation by activating T cell protein-tyrosine phosphatase. J Biol Chem 2010; 285:40114-24. [PMID: 20940300 DOI: 10.1074/jbc.m110.156729] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Integrin α1β1 is a collagen receptor that down-regulates collagen and reactive oxygen species (ROS) production, and mice lacking this receptor show increased ROS levels and exacerbated glomerular sclerosis following injury. Caveolin-1 (Cav-1) is a multifunctional protein that is tyrosine-phosphorylated in response to injury and has been implicated in ROS-mediated injury. Cav-1 interacts with integrins, and integrin α1β1 binds/activates T cell protein-tyrosine phosphatase (TCPTP), which is homologous to the tyrosine phosphatase PTP1B known to dephosphorylate Cav-1. In this study, we analyzed whether phosphorylated Cav-1 (pCav-1) is a substrate of TCPTP and if integrin α1β1 is essential for promoting TCPTP-mediated Cav-1 dephosphorylation. We found that Cav-1 phosphorylation is significantly higher in cells lacking integrin α1β1 at base line and following oxidative stress. Overexpression of TCPTP leads to reduced pCav-1 levels only in cells expressing integrin α1β1. Using solid phase binding assays, we demonstrated that 1) purified Cav-1 directly interacts with TCPTP and the integrin α1 subunit, 2) pCav-1 is a substrate of TCPTP, and 3) TCPTP-mediated Cav-1 dephosphorylation is highly increased by the addition of purified integrin α1β1 or an integrin α1 cytoplasmic peptide to which TCPTP has been shown to bind. Thus, our results demonstrate that pCav-1 is a new substrate of TCPTP and that integrin α1β1 acts as a negative regulator of Cav-1 phosphorylation by activating TCPTP. This could explain the protective function of integrin α1β1 in oxidative stress-mediated damage and why integrin α1-null mice are more susceptible to fibrosis following injury.
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Affiliation(s)
- Corina M Borza
- Department of Medicine, Division of Nephrology, Vanderbilt University, Nashville, Tennessee 37212-2372, USA.
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13
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Borza CM, Borza DB, Pedchenko V, Saleem MA, Mathieson PW, Sado Y, Hudson HM, Pozzi A, Saus J, Abrahamson DR, Zent R, Hudson BG. Human podocytes adhere to the KRGDS motif of the alpha3alpha4alpha5 collagen IV network. J Am Soc Nephrol 2008; 19:677-84. [PMID: 18235087 DOI: 10.1681/asn.2007070793] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Podocyte adhesion to the glomerular basement membrane is required for proper function of the glomerular filtration barrier. However, the mechanism whereby podocytes adhere to collagen IV networks, a major component of the glomerular basement membrane, is poorly understood. The predominant collagen IV network is composed of triple helical protomers containing the alpha3alpha4alpha5 chains. The protomers connect via the trimeric noncollagenous (NC1) domains to form hexamers at the interface. Because the NC1 domains of this network can potentially support integrin-dependent cell adhesion, it was determined whether individual NC1 monomers or alpha3alpha4alpha5 hexamers support podocyte adhesion. It was found that, although human podocytes did not adhere to NC1 domains proper, they did adhere via integrin alphavbeta3 to a KRGDS motif located adjacent to alpha3NC1 domains. Because the KRGDS motif is a site of phosphorylation, its interactions with integrin alphavbeta3 may play a critical role in cell signaling in physiologic and pathologic states.
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14
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Borza CM, Pozzi A, Borza DB, Pedchenko V, Hellmark T, Hudson BG, Zent R. Integrin alpha3beta1, a novel receptor for alpha3(IV) noncollagenous domain and a trans-dominant Inhibitor for integrin alphavbeta3. J Biol Chem 2006; 281:20932-20939. [PMID: 16731529 DOI: 10.1074/jbc.m601147200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Exogenous soluble human alpha3 noncollagenous (NC1) domain of collagen IV inhibits angiogenesis and tumor growth. These biological functions are attributed to the binding of alpha3NC1 to integrin alphavbeta3. However, in some tumor cells that express integrin alphavbeta3, the alpha3NC1 domain does not inhibit proliferation, suggesting that integrin alphavbeta3 expression is not sufficient to mediate the anti-tumorigenic activity of this domain. Therefore, in the present study, we searched for novel binding receptors for the soluble alpha3NC1 domain in cells lacking alphavbeta3 integrin. In these cells, soluble alpha3NC1 bound integrin alpha3beta1; however, unlike alphavbeta3, alpha3beta1 integrin did not mediate cell adhesion to immobilized alpha3NC1 domain. Interestingly, in cells lacking integrin alpha3beta1, adhesion to the alpha3NC1 domain was enhanced due to activation of integrin alphavbeta3. These findings indicate that integrin alpha3beta1 is a receptor for the alpha3NC1 domain and transdominantly inhibits integrin alphavbeta3 activation. Thus integrin alpha3beta1, in conjunction with integrin alphavbeta3, modulates cellular responses to the alpha3NC1 domain, which may be pivotal in the mechanism underpinning its anti-angiogenic and anti-tumorigenic activities.
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Affiliation(s)
- Corina M Borza
- Division of Nephrology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2372.
| | - Ambra Pozzi
- Division of Nephrology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2372; Department of Research Medicine, Veterans Affairs Hospital, Nashville, Tennessee 37232-2372
| | - Dorin-Bogdan Borza
- Division of Nephrology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2372
| | - Vadim Pedchenko
- Division of Nephrology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2372
| | - Thomas Hellmark
- Kidney Research Laboratory, Lund University, S-22185 Lund, Sweden
| | - Billy G Hudson
- Division of Nephrology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2372.
| | - Roy Zent
- Division of Nephrology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2372; Department of Research Medicine, Veterans Affairs Hospital, Nashville, Tennessee 37232-2372.
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15
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Abstract
The core fusion machinery of all herpesviruses consists of three conserved glycoproteins, gB and gHgL, suggesting a common mechanism for virus cell fusion, but fusion of Epstein-Barr virus (EBV) with B cells and epithelial cells is initiated differently. Fusion with B cells requires a fourth protein, gp42, which complexes with gHgL and interacts with HLA class II, the B-cell coreceptor. Fusion with an epithelial cell does not require gp42 but requires interaction of gHgL with a novel epithelial cell coreceptor. Epithelial cell fusion can be inhibited by gp42 binding to gHgL and by antibodies to gH that fail to block B-cell fusion. This suggests that regions of gHgL initiating fusion with each cell are separable from each other and from regions involved in fusion itself. To address this possibility we mapped the region of gH recognized by a monoclonal antibody to gH that blocks EBV fusion with epithelial cells but not B cells by making a series of chimeras with the gH homolog of rhesus lymphocryptovirus. Proteins with mutations engineered within this region included those that preferentially mediate fusion with B cells, those that preferentially mediate fusion with epithelial cells, and those that mediate fusion with neither cell type. These results support the hypothesis that the core fusion function of gH is the same for B cells and epithelial cells and that it differs only in the way in which it is triggered into a functionally active state.
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Affiliation(s)
- Liguo Wu
- School of Biological Sciences, University of Missouri--Kansas City, USA
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16
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Abstract
Epstein-Barr virus (EBV) is a lymphotropic herpesvirus. However, access to B lymphocytes during primary infection may be facilitated by replication in mucosal epithelial cells. Attachment and penetration of EBV into these two cell types are fundamentally different. Both the distribution of receptors and the cellular origin of the virus impact the efficiency of infection. Epithelial cells potentially offer a wide range of receptors with which virus can interact. We report here on analyses of epithelial cells expressing different combinations of receptors. We find that the stoichiometry of the virus glycoprotein complex that includes gHgL and gp42 affects the use of gHgL not just for entry into epithelial cells but also for attachment. Penetration can be mediated efficiently with either a coreceptor for gp42 or gHgL, but the use of gHgL for attachment as well as penetration greatly compromises its ability to mediate entry.
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Affiliation(s)
- Corina M Borza
- School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri, USA
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17
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Abstract
Epstein-Barr virus is ubiquitous and is causally implicated in lymphoid and epithelial malignancies. Virus invades oropharyngeal mucosa and establishes latency in B lymphocytes. Reactivating lymphocytes shed virus into saliva for spread to new hosts. A complex of three virus glycoproteins, gH, gL and gp42, is essential for entry. B-cell entry requires binding of gp42 to human leukocyte antigen (HLA) class II whereas entry into epithelial cells lacking HLA class II requires complexes without gp42. To accommodate infection of each, the virus carries both three-part and two-part complexes. We show here that HLA class II in the virus-producing cell alters the ratio of three-part to two-part complexes. As a consequence, virus originating in epithelial cells efficiently infects B cells whereas B-cell derived virus better infects epithelial cells. This molecular switch is a novel strategy that could alter tropism of virus from epithelium to B cells and then back to epithelium in a new host.
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Affiliation(s)
- Corina M Borza
- School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri, USA.
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18
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Ruf IK, Rhyne PW, Yang H, Borza CM, Hutt-Fletcher LM, Cleveland JL, Sample JT. EBV regulates c-MYC, apoptosis, and tumorigenicity in Burkitt's lymphoma. Curr Top Microbiol Immunol 2002; 258:153-60. [PMID: 11443860 DOI: 10.1007/978-3-642-56515-1_10] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Affiliation(s)
- I K Ruf
- Program in Viral Oncogenesis and Tumor Immunology, Department of Virology and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
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19
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Molesworth SJ, Lake CM, Borza CM, Turk SM, Hutt-Fletcher LM. Epstein-Barr virus gH is essential for penetration of B cells but also plays a role in attachment of virus to epithelial cells. J Virol 2000; 74:6324-32. [PMID: 10864642 PMCID: PMC112138 DOI: 10.1128/jvi.74.14.6324-6332.2000] [Citation(s) in RCA: 194] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Entry of Epstein-Barr virus (EBV) into B cells is initiated by attachment of glycoprotein gp350 to the complement receptor type 2 (CR2). A complex of three glycoproteins, gH, gL, and gp42, is subsequently required for penetration. Gp42 binds to HLA class II, which functions as an entry mediator or coreceptor and, by analogy with other herpesviruses, gH is then thought to be involved virus-cell fusion. However, entry of virus into epithelial cells is thought to be different. It can be initiated by attachment by an unknown glycoprotein in the absence of CR2. There is no interaction between gp42 and HLA class II and instead a distinct complex of only the two glycoproteins gH and gL interacts with a novel entry mediator. Again, by analogy with other viruses gH is thought to be critical to fusion. To investigate further the different roles of gH in infection of the two cell types and to examine its influence on the assembly of the gH-gL-gp42 complex, we constructed two viruses, one in which the gH open reading frame was interrupted by a cassette expressing a neomycin resistance gene and the gene for green fluorescent protein and one as a control in which the neighboring nonessential thymidine kinase gene was interrupted with the same cassette. Virus lacking gH exited from cells normally, although loss of gH resulted in rapid turnover of gL and gp42 as well. The virus bound normally to B lymphocytes but could not infect them unless cells and bound virus were treated with polyethylene glycol to induce fusion. In contrast, virus that lacked the gH complex was impaired in attachment to epithelial cells and the effects of monoclonal antibodies to gH implied that this resulted from loss of gH rather than other members of the complex. These results suggest a role for gH in both attachment and penetration into epithelial cells.
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MESH Headings
- Animals
- B-Lymphocytes/virology
- Blotting, Southern
- Blotting, Western
- Cell Line
- Epithelial Cells/virology
- Glycoproteins/genetics
- Glycoproteins/metabolism
- Hemagglutinins, Viral/genetics
- Hemagglutinins, Viral/metabolism
- Herpesvirus 4, Human/genetics
- Herpesvirus 4, Human/metabolism
- Herpesvirus 4, Human/pathogenicity
- Herpesvirus 4, Human/physiology
- Humans
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/metabolism
- Molecular Chaperones/genetics
- Molecular Chaperones/metabolism
- Mutagenesis, Site-Directed
- Open Reading Frames
- Polyethylene Glycols/pharmacology
- Receptors, Complement 3d/metabolism
- Recombination, Genetic
- Sheep
- Viral Proteins/genetics
- Viral Proteins/metabolism
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Affiliation(s)
- S J Molesworth
- School of Biological Science, University of Missouri-Kansas City, Kansas City, Missouri 64110, USA
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20
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Ruf IK, Rhyne PW, Yang H, Borza CM, Hutt-Fletcher LM, Cleveland JL, Sample JT. Epstein-barr virus regulates c-MYC, apoptosis, and tumorigenicity in Burkitt lymphoma. Mol Cell Biol 1999; 19:1651-60. [PMID: 10022853 PMCID: PMC83959 DOI: 10.1128/mcb.19.3.1651] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Loss of the Epstein-Barr virus (EBV) genome from Akata Burkitt lymphoma (BL) cells is coincident with a loss of malignant phenotype, despite the fact that Akata and other EBV-positive BL cells express a restricted set of EBV gene products (type I latency) that are not known to overtly affect cell growth. Here we demonstrate that reestablishment of type I latency in EBV-negative Akata cells restores tumorigenicity and that tumorigenic potential correlates with an increased resistance to apoptosis under growth-limiting conditions. The antiapoptotic effect of EBV was associated with a higher level of Bcl-2 expression and an EBV-dependent decrease in steady-state levels of c-MYC protein. Although the EBV EBNA-1 protein is expressed in all EBV-associated tumors and is reported to have oncogenic potential, enforced expression of EBNA-1 alone in EBV-negative Akata cells failed to restore tumorigenicity or EBV-dependent down-regulation of c-MYC. These data provide direct evidence that EBV contributes to the tumorigenic potential of Burkitt lymphoma and suggest a novel model whereby a restricted latency program of EBV promotes B-cell survival, and thus virus persistence within an immune host, by selectively targeting the expression of c-MYC.
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Affiliation(s)
- I K Ruf
- Program in Viral Oncogenesis and Tumor Immunology, Department of Virology and Molecular Biology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
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21
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Borza CM, Hutt-Fletcher LM. Epstein-Barr virus recombinant lacking expression of glycoprotein gp150 infects B cells normally but is enhanced for infection of epithelial cells. J Virol 1998; 72:7577-82. [PMID: 9696856 PMCID: PMC110006 DOI: 10.1128/jvi.72.9.7577-7582.1998] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Glycoprotein gp150 is a highly glycosylated protein encoded by the BDLF3 open reading frame of Epstein-Barr virus (EBV). It does not have a homolog in the alpha- and betaherpesviruses, and its function is not known. To determine whether the protein is essential for replication of EBV in vitro, a recombinant virus which lacked its expression was made. The recombinant virus had no defects in assembly, egress, binding, or infectivity for B cells or epithelial cells. Infection of epithelial cells was, however, enhanced. The glycoprotein was sensitive to digestion with a glycoprotease that digests sialomucins, but no adhesion to cells that express selectins that bind to sialomucin ligands could be detected.
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Affiliation(s)
- C M Borza
- School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri 64110, USA
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22
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Abstract
Heme-hemopexin supports and stimulates proliferation of human acute T-lymphoblastic (MOLT-3) cells, suggesting the participation of heme in cell growth and division. MOLT-3 cells express approximately 58,000 hemopexin receptors per cell (apparent Kd 20 nM), of which about 20% are on the cell surface. Binding is dose- and temperature-dependent, and growth in serum-free IMDM medium is stimulated by 100-1000 nM heme-hemopexin, consistent with the high affinity of the receptor for hemopexin, and maximal growth is seen in response to 500 nM complex. Growth was similar in defined minimal medium supplemented with either low concentrations of heme-hemopexin or iron-transferrin, and either of these complexes were about 80% as effective as a serum supplement. Heme-hemopexin, but not apo-hemopexin, reversed the growth inhibition caused by desferrioxamine showing that heme-iron derived from heme catabolism is used for cell growth. Cobalt-protoporphyrin (CoPP)-hemopexin, which binds to the receptor but is not transported intracellularly [Smith et al., (1993) J. Biol. Chem. 268, 7365], also stimulated cell proliferation in serum-free IMDM but did not "rescue" the cells from desferrioxamine. Furthermore, CoPP-hemopexin effectively competed for the hemopexin receptor with heme-hemopexin and diminished its growth stimulatory effects. In addition, protein kinase C (PKC) is translocated to the plasma membrane within 5 min after heme-hemopexin is added to the medium, reaches maximum activity within 5-10 min, and declines to unstimulated levels by 30 min. Heme-hemopexin and CoPP-hemopexin both augmented MOLT-3 cell growth stimulated by serum. Thus, heme-hemopexin not only functions as an iron source for T-cells but occupancy of the hemopexin receptor itself triggers signaling pathway(s) involved in the regulation of cell growth. The stimulation of growth of human T-lymphocytes by heme-hemopexin is likely to be a physiologically relevant mechanism at sites of injury, infection, and inflammation.
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Affiliation(s)
- A Smith
- Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City 64110-2499, USA.
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Waterborg JH, Robertson AJ, Tatar DL, Borza CM, Davie JR. Histones of Chlamydomonas reinhardtii. Synthesis, acetylation, and methylation. Plant Physiol 1995; 109:393-407. [PMID: 7480339 PMCID: PMC157602 DOI: 10.1104/pp.109.2.393] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Histones of the green alga Chlamydomonas reinhardtii were prepared by a new method and fractionated by reversed-phase high-performance liquid chromatography. Acid-urea-Triton gel analysis and tritiated acetate labeling demonstrated high levels of steady-state acetylation for the single histone H3 protein, in contrast to low levels on histones H4 and H2B. Twenty percent of histone H3 is subject to dynamic acetylation with, on average, three acetylated lysine residues per protein molecule. Histone synthesis in light-dark-synchronized cultures was biphasic with pattern differences between two histone H1 variants, between two H2A variants, and between H2B and ubiquitinated H2B. Automated protein sequence analysis of histone H3 demonstrated a site-specific pattern of steady-state acetylation between 7 and 17% at five of the six amino-terminal lysines and of monomethylation between 5 and 81% at five of the eight amino-terminal lysines in a pattern that may limit dynamic acetylation. An algal histone H3 sequence was confirmed by protein sequencing with a single threonine as residue 28 instead of the serine28-alanine29 sequence, present in all other known plant and animal H3 histones.
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Affiliation(s)
- J H Waterborg
- School of Biological Sciences, University of Missouri-Kansas City 64110-2499, USA
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