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Yang SNY, Maher B, Wang C, Wagstaff KM, Fraser JE, Jans DA. High Throughput Screening Targeting the Dengue NS3-NS5 Interface Identifies Antivirals against Dengue, Zika and West Nile Viruses. Cells 2022; 11:730. [PMID: 35203378 PMCID: PMC8870125 DOI: 10.3390/cells11040730] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 02/03/2022] [Accepted: 02/11/2022] [Indexed: 12/04/2022] Open
Abstract
Dengue virus (DENV) threatens almost 70% of the world's population, with no effective therapeutic currently available and controversy surrounding the one approved vaccine. A key factor in dengue viral replication is the interaction between DENV nonstructural proteins (NS) 5 and 3 (NS3) in the infected cell. Here, we perform a proof-of-principle high-throughput screen to identify compounds targeting the NS5-NS3 binding interface. We use a range of approaches to show for the first time that two small molecules-repurposed drugs I-OMe tyrphostin AG538 (I-OMe-AG238) and suramin hexasodium (SHS)-inhibit NS5-NS3 binding at low μM concentration through direct binding to NS5 that impacts thermostability. Importantly, both have strong antiviral activity at low μM concentrations against not only DENV-2, but also Zika virus (ZIKV) and West Nile virus (WNV). This work highlights the NS5-NS3 binding interface as a viable target for the development of anti-flaviviral therapeutics.
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Affiliation(s)
| | | | | | | | | | - David A. Jans
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Monash, VIC 3800, Australia; (S.N.Y.Y.); (B.M.); (C.W.); (K.M.W.); (J.E.F.)
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2
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Joglekar MV, Sahu S, Wong WKM, Satoor SN, Dong CX, Farr RJ, Williams MD, Pandya P, Jhala G, Yang SNY, Chew YV, Hetherington N, Thiruchevlam D, Mitnala S, Rao GV, Reddy DN, Loudovaris T, Hawthorne WJ, Elefanty AG, Joglekar VM, Stanley EG, Martin D, Thomas HE, Tosh D, Dalgaard LT, Hardikar AA. A Pro-Endocrine Pancreatic Islet Transcriptional Program Established During Development Is Retained in Human Gallbladder Epithelial Cells. Cell Mol Gastroenterol Hepatol 2022; 13:1530-1553.e4. [PMID: 35032693 PMCID: PMC9043310 DOI: 10.1016/j.jcmgh.2022.01.008] [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] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Revised: 01/06/2022] [Accepted: 01/06/2022] [Indexed: 12/10/2022]
Abstract
BACKGROUND & AIMS Pancreatic islet β-cells are factories for insulin production; however, ectopic expression of insulin also is well recognized. The gallbladder is a next-door neighbor to the developing pancreas. Here, we wanted to understand if gallbladders contain functional insulin-producing cells. METHODS We compared developing and adult mouse as well as human gallbladder epithelial cells and islets using immunohistochemistry, flow cytometry, enzyme-linked immunosorbent assays, RNA sequencing, real-time polymerase chain reaction, chromatin immunoprecipitation, and functional studies. RESULTS We show that the epithelial lining of developing, as well as adult, mouse and human gallbladders naturally contain interspersed cells that retain the capacity to actively transcribe, translate, package, and release insulin. We show that human gallbladders also contain functional insulin-secreting cells with the potential to naturally respond to glucose in vitro and in situ. Notably, in a non-obese diabetic (NOD) mouse model of type 1 diabetes, we observed that insulin-producing cells in the gallbladder are not targeted by autoimmune cells. Interestingly, in human gallbladders, insulin splice variants are absent, although insulin splice forms are observed in human islets. CONCLUSIONS In summary, our biochemical, transcriptomic, and functional data in mouse and human gallbladder epithelial cells collectively show the evolutionary and developmental similarities between gallbladder and the pancreas that allow gallbladder epithelial cells to continue insulin production in adult life. Understanding the mechanisms regulating insulin transcription and translation in gallbladder epithelial cells would help guide future studies in type 1 diabetes therapy.
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Affiliation(s)
- Mugdha V Joglekar
- Diabetes and Islet Biology Group, School of Medicine, Western Sydney University, Campbelltown, New South Wales, Australia
| | - Subhshri Sahu
- Diabetes and Islet Biology Group, School of Medicine, Western Sydney University, Campbelltown, New South Wales, Australia
| | - Wilson K M Wong
- Diabetes and Islet Biology Group, School of Medicine, Western Sydney University, Campbelltown, New South Wales, Australia
| | - Sarang N Satoor
- Diabetes and Islet Biology Group, School of Medicine, Western Sydney University, Campbelltown, New South Wales, Australia
| | - Charlotte X Dong
- Diabetes and Islet Biology Group, School of Medicine, Western Sydney University, Campbelltown, New South Wales, Australia
| | - Ryan J Farr
- Diabetes and Islet Biology Group, School of Medicine, Western Sydney University, Campbelltown, New South Wales, Australia
| | - Michael D Williams
- Diabetes and Islet Biology Group, School of Medicine, Western Sydney University, Campbelltown, New South Wales, Australia
| | - Prapti Pandya
- Diabetes and Islet Biology Group, School of Medicine, Western Sydney University, Campbelltown, New South Wales, Australia
| | - Gaurang Jhala
- Immunology and Diabetes Group, St. Vincent's Institute for Medical Research, Victoria, Australia
| | - Sundy N Y Yang
- Diabetes and Islet Biology Group, School of Medicine, Western Sydney University, Campbelltown, New South Wales, Australia
| | - Yi Vee Chew
- The Westmead Institute for Medical Research, Westmead Millenium Institute, University of Sydney, Westmead, New South Wales, Australia
| | - Nicola Hetherington
- Diabetes and Islet Biology Group, School of Medicine, Western Sydney University, Campbelltown, New South Wales, Australia
| | - Dhan Thiruchevlam
- Department of Gastroenterology, St. Vincent's Hospital, Melbourne, Victoria, Australia
| | - Sasikala Mitnala
- Surgical Gastroenterology Research, Asian Institute of Gastroenterology, Hyderabad, India
| | - Guduru V Rao
- Surgical Gastroenterology Research, Asian Institute of Gastroenterology, Hyderabad, India
| | | | - Thomas Loudovaris
- Immunology and Diabetes Group, St. Vincent's Institute for Medical Research, Victoria, Australia
| | - Wayne J Hawthorne
- The Westmead Institute for Medical Research, Westmead Millenium Institute, University of Sydney, Westmead, New South Wales, Australia
| | - Andrew G Elefanty
- Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | | | - Edouard G Stanley
- Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - David Martin
- Upper Gastrointestinal Surgery, Strathfield Hospital, Strathfield, New South Wales, Australia
| | - Helen E Thomas
- Immunology and Diabetes Group, St. Vincent's Institute for Medical Research, Victoria, Australia
| | - David Tosh
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | - Louise T Dalgaard
- Section of Eukaryotic Cell Biology, Department of Science and Environment, Roskilde University, Roskilde, Denmark
| | - Anandwardhan A Hardikar
- Diabetes and Islet Biology Group, School of Medicine, Western Sydney University, Campbelltown, New South Wales, Australia.
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3
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Yang SNY, Atkinson SC, Wang C, Lee A, Bogoyevitch MA, Borg NA, Jans DA. The broad spectrum antiviral ivermectin targets the host nuclear transport importin α/β1 heterodimer. Antiviral Res 2020; 177:104760. [PMID: 32135219 DOI: 10.1016/j.antiviral.2020.104760] [Citation(s) in RCA: 193] [Impact Index Per Article: 48.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 02/28/2020] [Accepted: 02/28/2020] [Indexed: 12/11/2022]
Abstract
Infection by RNA viruses such as human immunodeficiency virus (HIV)-1, influenza, and dengue virus (DENV) represent a major burden for human health worldwide. Although RNA viruses replicate in the infected host cell cytoplasm, the nucleus is central to key stages of the infectious cycle of HIV-1 and influenza, and an important target of DENV nonstructural protein 5 (NS5) in limiting the host antiviral response. We previously identified the small molecule ivermectin as an inhibitor of HIV-1 integrase nuclear entry, subsequently showing ivermectin could inhibit DENV NS5 nuclear import, as well as limit infection by viruses such as HIV-1 and DENV. We show here that ivermectin's broad spectrum antiviral activity relates to its ability to target the host importin (IMP) α/β1 nuclear transport proteins responsible for nuclear entry of cargoes such as integrase and NS5. We establish for the first time that ivermectin can dissociate the preformed IMPα/β1 heterodimer, as well as prevent its formation, through binding to the IMPα armadillo (ARM) repeat domain to impact IMPα thermal stability and α-helicity. We show that ivermectin inhibits NS5-IMPα interaction in a cell context using quantitative bimolecular fluorescence complementation. Finally, we show for the first time that ivermectin can limit infection by the DENV-related West Nile virus at low (μM) concentrations. Since it is FDA approved for parasitic indications, ivermectin merits closer consideration as a broad spectrum antiviral of interest.
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Affiliation(s)
- Sundy N Y Yang
- Nuclear Signalling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic, 3800, Australia
| | - Sarah C Atkinson
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic, 3800, Australia
| | - Chunxiao Wang
- Nuclear Signalling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic, 3800, Australia
| | - Alexander Lee
- Nuclear Signalling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic, 3800, Australia
| | - Marie A Bogoyevitch
- Department of Biochemistry and Molecular Biology, University of Melbourne, Melbourne, Australia
| | - Natalie A Borg
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic, 3800, Australia
| | - David A Jans
- Nuclear Signalling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic, 3800, Australia.
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Heaton SM, Atkinson SC, Sweeney MN, Yang SNY, Jans DA, Borg NA. Exportin-1-Dependent Nuclear Export of DEAD-box Helicase DDX3X is Central to its Role in Antiviral Immunity. Cells 2019; 8:E1181. [PMID: 31575075 PMCID: PMC6848931 DOI: 10.3390/cells8101181] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 09/16/2019] [Accepted: 09/28/2019] [Indexed: 12/14/2022] Open
Abstract
DEAD-box helicase 3, X-linked (DDX3X) regulates the retinoic acid-inducible gene I (RIG-I)-like receptor (RLR)-mediated antiviral response, but can also be a host factor contributing to the replication of viruses of significance to human health, such as human immunodeficiency virus type 1 (HIV-1). These roles are mediated in part through its ability to actively shuttle between the nucleus and the cytoplasm to modulate gene expression, although the trafficking mechanisms, and impact thereof on immune signaling and viral infection, are incompletely defined. We confirm that DDX3X nuclear export is mediated by the nuclear transporter exportin-1/CRM1, dependent on an N-terminal, leucine-rich nuclear export signal (NES) and the monomeric guanine nucleotide binding protein Ran in activated GTP-bound form. Transcriptome profiling and ELISA show that exportin-1-dependent export of DDX3X to the cytoplasm strongly impacts IFN-β production and the upregulation of immune genes in response to infection. That this is key to DDX3X's antiviral role was indicated by enhanced infection by human parainfluenza virus-3 (hPIV-3)/elevated virus production when the DDX3X NES was inactivated. Our results highlight a link between nucleocytoplasmic distribution of DDX3X and its role in antiviral immunity, with strong relevance to hPIV-3, as well as other viruses such as HIV-1.
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Affiliation(s)
- Steven M Heaton
- Infection & Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia.
| | - Sarah C Atkinson
- Infection & Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia.
| | - Melissa N Sweeney
- Infection & Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia.
| | - Sundy N Y Yang
- Nuclear Signaling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia.
| | - David A Jans
- Nuclear Signaling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia.
| | - Natalie A Borg
- Infection & Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia.
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5
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Yang SNY, Atkinson SC, Fraser JE, Wang C, Maher B, Roman N, Forwood JK, Wagstaff KM, Borg NA, Jans DA. Novel Flavivirus Antiviral That Targets the Host Nuclear Transport Importin α/β1 Heterodimer. Cells 2019; 8:cells8030281. [PMID: 30909636 PMCID: PMC6468590 DOI: 10.3390/cells8030281] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 03/19/2019] [Accepted: 03/20/2019] [Indexed: 12/20/2022] Open
Abstract
Dengue virus (DENV) threatens almost 70% of the world’s population, with no effective vaccine or therapeutic currently available. A key contributor to infection is nuclear localisation in the infected cell of DENV nonstructural protein 5 (NS5) through the action of the host importin (IMP) α/β1 proteins. Here, we used a range of microscopic, virological and biochemical/biophysical approaches to show for the first time that the small molecule GW5074 has anti-DENV action through its novel ability to inhibit NS5–IMPα/β1 interaction in vitro as well as NS5 nuclear localisation in infected cells. Strikingly, GW5074 not only inhibits IMPα binding to IMPβ1, but can dissociate preformed IMPα/β1 heterodimer, through targeting the IMPα armadillo (ARM) repeat domain to impact IMPα thermal stability and α-helicity, as shown using analytical ultracentrifugation, thermostability analysis and circular dichroism measurements. Importantly, GW5074 has strong antiviral activity at low µM concentrations against not only DENV-2, but also zika virus and West Nile virus. This work highlights DENV NS5 nuclear targeting as a viable target for anti-flaviviral therapeutics.
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Affiliation(s)
- Sundy N Y Yang
- Nuclear Signaling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic. 3800, Australia.
| | - Sarah C Atkinson
- Infection & Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic. 3800, Australia.
| | - Johanna E Fraser
- Nuclear Signaling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic. 3800, Australia.
| | - Chunxiao Wang
- Nuclear Signaling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic. 3800, Australia.
| | - Belinda Maher
- Nuclear Signaling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic. 3800, Australia.
| | - Noelia Roman
- School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, NSW 2650, Australia.
| | - Jade K Forwood
- School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, NSW 2650, Australia.
| | - Kylie M Wagstaff
- Nuclear Signaling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic. 3800, Australia.
| | - Natalie A Borg
- Infection & Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic. 3800, Australia.
| | - David A Jans
- Nuclear Signaling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic. 3800, Australia.
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Wang C, Yang SNY, Smith K, Forwood JK, Jans DA. Nuclear import inhibitor N-(4-hydroxyphenyl) retinamide targets Zika virus (ZIKV) nonstructural protein 5 to inhibit ZIKV infection. Biochem Biophys Res Commun 2017; 493:1555-1559. [PMID: 28988109 DOI: 10.1016/j.bbrc.2017.10.016] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 10/03/2017] [Indexed: 12/31/2022]
Abstract
In the absence of approved therapeutics, Zika virus (ZIKV)'s recent prolific outbreaks in the Americas, together with impacts on unborn fetuses of infected mothers, make it a pressing human health concern worldwide. Although a key player in viral replication in the infected host cell cytoplasm, ZIKV non-structural protein 5 (NS5) appears to contribute integrally to pathogenesis by localising in the host cell nucleus, in similar fashion to NS5 from Dengue virus (DENV). We show here for the first time that ZIKV NS5 is recognized with high nanomolar affinity by the host cell importin α/β1 heterodimer, and that this interaction can be blocked by the novel DENV NS5 targeting inhibitor N-(4-hydroxyphenyl) retinamide (4-HPR). Importantly, we show that 4-HPR has potent anti-ZIKV activity at low μM concentrations. With an established safety profile for human use, 4-HPR represents an exciting possibility as an anti-ZIKV agent.
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Affiliation(s)
- Chunxiao Wang
- Nuclear Signaling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic. 3800, Australia
| | - Sundy N Y Yang
- Nuclear Signaling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic. 3800, Australia
| | - Kate Smith
- School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, NSW 2650, Australia
| | - Jade K Forwood
- School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, NSW 2650, Australia
| | - David A Jans
- Nuclear Signaling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic. 3800, Australia.
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7
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Yang SNY, Burch ML, Tannock LR, Evanko S, Osman N, Little PJ. Transforming growth factor-β regulation of proteoglycan synthesis in vascular smooth muscle: contribution to lipid binding and accelerated atherosclerosis in diabetes. J Diabetes 2010; 2:233-42. [PMID: 20923499 DOI: 10.1111/j.1753-0407.2010.00089.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Atherosclerosis is accelerated in the setting of diabetes, but the factors driving this phenomenon remain elusive. Hyperglycemia leads to elevated levels of transforming growth factor (TGF)-β and TGF-β has been implicated as a factor in atherosclerosis. Given the established association between hyperglycemia and elevated TGF-β, it is plausible that elevated TGF-β levels in diabetes play a pathogenic role in the development of accelerated atherosclerosis. TGF-β is a potent regulator of extracellular matrix synthesis, including many actions on proteoglycan synthesis that lead to increased binding to low-density lipoprotein and therefore potentially increased lipid retention in the vessel wall and accelerated atherosclerosis. TGF-β signals through the canonical TGF-β receptor I-mediated phosphorylation of Smad transcription factors and TGF-β signaling is also known to involve, positively and negatively, interactions with the mitogen-activated protein kinase pathways. The focus of the present review is on the effects of TGF-β on proteoglycan synthesis in vascular smooth muscle and particularly the signaling pathways through which TGF-β exerts its effects, because those pathways may be therapeutic targets for the prevention of pathological modifications in the proteoglycan component of the vessel wall in the vascular diseases of diabetes.
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Affiliation(s)
- Sundy N Y Yang
- Diabetes and Cell Biology Laboratory, Baker IDI Heart and Diabetes Institute, Monash University School of Medicine (Alfred Hospital), Faculty of Medicine, Nursing and Health Sciences, Melbourne, Victoria, Australia
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Burch ML, Ballinger ML, Yang SNY, Getachew R, Itman C, Loveland K, Osman N, Little PJ. Thrombin stimulation of proteoglycan synthesis in vascular smooth muscle is mediated by protease-activated receptor-1 transactivation of the transforming growth factor beta type I receptor. J Biol Chem 2010; 285:26798-26805. [PMID: 20571025 DOI: 10.1074/jbc.m109.092767] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [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
Growth factors modify the structure of the glycosaminoglycan (GAG) chains on biglycan leading to enhanced LDL binding. G-protein receptor-coupled agonists such as thrombin, signal changes the structure of proteoglycans produced by vascular smooth muscle cells (VSMCs). One component of classical G-protein-coupled receptor (GPCR) signaling invokes transactivation of protein tyrosine kinase receptors such as the epidermal growth factor receptor. Serine/threonine receptor growth factors such as transforming growth factor-(TGF)-beta are potent activators of proteoglycan synthesis. We have used the model of proteoglycan synthesis to demonstrate that the signaling paradigm of GPCR signaling can be extended to include the transactivation of serine/threonine receptor, specifically the TGF-beta type I receptor (TbetaRI) also known as activin-like kinase (ALK) V. Thrombin stimulated elongation of GAG chains and increased proteoglycan core protein expression and these responses were blocked by the TbetaRI antagonist, SB431542 and TbetaRI siRNA knockdown, as well as several protease-activated receptor (PAR)-1 antagonists. The canonical downstream response to TGF-beta is increased C-terminal phosphorylation of the transcription factor Smad2 generating phospho-Smad2C (phosphorylation of Smad2 C-terminal region). Thrombin stimulated increased phospho-Smad2C levels, and the response was blocked by SB431542 and JNJ5177094. The proteolytically inactive thrombin mimetic thrombin-receptor activating peptide also stimulated an increase in cytosolic phospho-Smad2C. Signaling pathways for growth factor regulated proteoglycan synthesis represent therapeutic targets for the prevention of atherosclerosis, but the novel finding of a GPCR-mediated transactivation of a serine/threonine growth factor receptor almost certainly has implications well beyond the synthesis of proteoglycans.
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Affiliation(s)
- Micah L Burch
- Diabetes and Cell Biology Laboratory, BakerIDI Heart and Diabetes Institute, Melbourne, 3004 Victoria, Australia; Departments of Medicine and Immunology, Central and Eastern Clinical School, Alfred Hospital, Monash University, Melbourne, 3004 Victoria, Australia
| | - Mandy L Ballinger
- Diabetes and Cell Biology Laboratory, BakerIDI Heart and Diabetes Institute, Melbourne, 3004 Victoria, Australia
| | - Sundy N Y Yang
- Diabetes and Cell Biology Laboratory, BakerIDI Heart and Diabetes Institute, Melbourne, 3004 Victoria, Australia
| | - Robel Getachew
- Diabetes and Cell Biology Laboratory, BakerIDI Heart and Diabetes Institute, Melbourne, 3004 Victoria, Australia
| | - Catherine Itman
- Departments of Biochemistry & Molecular Biology and Anatomy & Developmental Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Kate Loveland
- Departments of Biochemistry & Molecular Biology and Anatomy & Developmental Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Narin Osman
- Diabetes and Cell Biology Laboratory, BakerIDI Heart and Diabetes Institute, Melbourne, 3004 Victoria, Australia; Departments of Medicine and Immunology, Central and Eastern Clinical School, Alfred Hospital, Monash University, Melbourne, 3004 Victoria, Australia
| | - Peter J Little
- Diabetes and Cell Biology Laboratory, BakerIDI Heart and Diabetes Institute, Melbourne, 3004 Victoria, Australia; Departments of Medicine and Immunology, Central and Eastern Clinical School, Alfred Hospital, Monash University, Melbourne, 3004 Victoria, Australia.
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9
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Yang SNY, Takeda AAS, Fontes MRM, Harris JM, Jans DA, Kobe B. Probing the specificity of binding to the major nuclear localization sequence-binding site of importin-alpha using oriented peptide library screening. J Biol Chem 2010; 285:19935-46. [PMID: 20406804 DOI: 10.1074/jbc.m109.079574] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Importin-alpha is the nuclear import receptor that recognizes the classic monopartite and bipartite nuclear localization sequences (cNLSs), which contain one or two clusters of basic amino acids, respectively. Different importin-alpha paralogs in a single organism are specific for distinct repertoires of cargos. Structural studies revealed that monopartite cNLSs and the C-terminal basic clusters of the bipartite cNLSs bind to the same site on importin-alpha, termed the major cNLS-binding site. We used an oriented peptide library approach with five degenerate positions to probe the specificity of the major cNLS-binding site in importin-alpha. We identified the sequences KKKRR, KKKRK, and KKRKK as the optimal sequences for binding to this site for mouse importin-alpha2, human importin-alpha1, and human importin-alpha5, respectively. The crystal structure of mouse importin-alpha2 with its optimal peptide confirmed the expected binding mode resembling the binding of simian virus 40 large tumor-antigen cNLS. Binding assays confirmed that the peptides containing these sequences bound to the corresponding proteins with low nanomolar affinities. Nuclear import assays showed that the sequences acted as functional cNLSs, with specificity for particular importin-alphas. This is the first time that structural information has been linked to an oriented peptide library screening approach for importin-alpha; the results will contribute to understanding of the sequence determinants of cNLSs, and may help identify as yet unidentified cNLSs in novel proteins.
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Affiliation(s)
- Sundy N Y Yang
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Centre for Infectious Disease Research, University of Queensland, Brisbane, Queensland 4072, Australia
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Yang SNY, Burch ML, Getachew R, Ballinger ML, Osman N, Little PJ. Growth factor-mediated hyper-elongation of glycosaminoglycan chains on biglycan requires transcription and translation. Arch Physiol Biochem 2009; 115:147-54. [PMID: 19580379 DOI: 10.1080/13813450903110754] [Citation(s) in RCA: 16] [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] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The mechanism through which growth factors cause glycosaminoglycan (GAG) hyper-elongation is unclear. We have investigated the role of transcription and translation on the GAG hyper-elongation effect of platelet-derived growth factor (PDGF) in human vascular smooth muscle cells (VSMCs). To determine if the response involves specific signalling pathways or the process of GAG hyper-elongation we have also investigated the effects of epidermal growth factor (EGF), transforming growth factor-beta (TGF-beta) and thrombin. We report that both actinomycin D and cycloheximide completely abolished the ability of PDGF to stimulate radiosulphate incorporation and GAG elongation into secreted proteoglycans, and to increase the size of xyloside GAGs. Blocking de novo protein synthesis completely prevented the action of all growth factors tested to elongate GAG chains. These results lay a foundation for further investigation into the genes and proteins implicated in this response.
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Affiliation(s)
- Sundy N Y Yang
- BakerIDI Heart and Diabetes Institute, Diabetes and Cell Biology Laboratory, Melbourne, VIC, 3004, Australia
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