1
|
Xu X, Yin K, Wu R. Systematic Investigation of the Trafficking of Glycoproteins on the Cell Surface. Mol Cell Proteomics 2024; 23:100761. [PMID: 38593903 PMCID: PMC11087972 DOI: 10.1016/j.mcpro.2024.100761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 03/30/2024] [Accepted: 04/03/2024] [Indexed: 04/11/2024] Open
Abstract
Glycoproteins located on the cell surface play a pivotal role in nearly every extracellular activity. N-glycosylation is one of the most common and important protein modifications in eukaryotic cells, and it often regulates protein folding and trafficking. Glycosylation of cell-surface proteins undergoes meticulous regulation by various enzymes in the endoplasmic reticulum (ER) and the Golgi, ensuring their proper folding and trafficking to the cell surface. However, the impacts of protein N-glycosylation, N-glycan maturity, and protein folding status on the trafficking of cell-surface glycoproteins remain to be explored. In this work, we comprehensively and site-specifically studied the trafficking of cell-surface glycoproteins in human cells. Integrating metabolic labeling, bioorthogonal chemistry, and multiplexed proteomics, we investigated 706 N-glycosylation sites on 396 cell-surface glycoproteins in monocytes, either by inhibiting protein N-glycosylation, disturbing N-glycan maturation, or perturbing protein folding in the ER. The current results reveal their distinct impacts on the trafficking of surface glycoproteins. The inhibition of protein N-glycosylation dramatically suppresses the trafficking of many cell-surface glycoproteins. The N-glycan immaturity has more substantial effects on proteins with high N-glycosylation site densities, while the perturbation of protein folding in the ER exerts a more pronounced impact on surface glycoproteins with larger sizes. Furthermore, for N-glycosylated proteins, their trafficking to the cell surface is related to the secondary structures and adjacent amino acid residues of glycosylation sites. Systematic analysis of surface glycoprotein trafficking advances our understanding of the mechanisms underlying protein secretion and surface presentation.
Collapse
Affiliation(s)
- Xing Xu
- School of Chemistry and Biochemistry and the Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Kejun Yin
- School of Chemistry and Biochemistry and the Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Ronghu Wu
- School of Chemistry and Biochemistry and the Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia, USA.
| |
Collapse
|
2
|
Akram M, Hameed S, Hassan A, Khan KM. Development in the Inhibition of Dengue Proteases as Drug Targets. Curr Med Chem 2024; 31:2195-2233. [PMID: 37723635 DOI: 10.2174/0929867331666230918110144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 06/24/2023] [Accepted: 08/04/2023] [Indexed: 09/20/2023]
Abstract
BACKGROUND Viral infections continue to increase morbidity and mortality severely. The flavivirus genus has fifty different species, including the dengue, Zika, and West Nile viruses that can infect 40% of individuals globally, who reside in at least a hundred different countries. Dengue, one of the oldest and most dangerous human infections, was initially documented by the Chinese Medical Encyclopedia in the Jin period. It was referred to as "water poison," connected to flying insects, i.e., Aedes aegypti and Aedes albopictus. DENV causes some medical expressions like dengue hemorrhagic fever, acute febrile illness, and dengue shock syndrome. OBJECTIVE According to the World Health Organization report of 2012, 2500 million people are in danger of contracting dengue fever worldwide. According to a recent study, 96 million of the 390 million dengue infections yearly show some clinical or subclinical severity. There is no antiviral drug or vaccine to treat this severe infection. It can be controlled by getting enough rest, drinking plenty of water, and using painkillers. The first dengue vaccine created by Sanofi, called Dengvaxia, was previously approved by the USFDA in 2019. All four serotypes of the DENV1-4 have shown re-infection in vaccine recipients. However, the usage of Dengvaxia has been constrained by its adverse effects. CONCLUSION Different classes of compounds have been reported against DENV, such as nitrogen-containing heterocycles (i.e., imidazole, pyridine, triazoles quinazolines, quinoline, and indole), oxygen-containing heterocycles (i.e., coumarins), and some are mixed heterocyclic compounds of S, N (thiazole, benzothiazine, and thiazolidinediones), and N, O (i.e., oxadiazole). There have been reports of computationally designed compounds to impede the molecular functions of specific structural and non-structural proteins as potential therapeutic targets. This review summarized the current progress in developing dengue protease inhibitors.
Collapse
Affiliation(s)
- Muhammad Akram
- Department of Chemistry, Quaid-i-Azam University, Islamabad, 45320, Pakistan
| | - Shehryar Hameed
- H.E.J. Research Institute of Chemistry, International Centre for Chemical and Biological Sciences, University of Karachi, Karachi, 75720, Pakistan
| | - Abbas Hassan
- Department of Chemistry, Quaid-i-Azam University, Islamabad, 45320, Pakistan
| | - Khalid Mohammed Khan
- H.E.J. Research Institute of Chemistry, International Centre for Chemical and Biological Sciences, University of Karachi, Karachi, 75720, Pakistan
| |
Collapse
|
3
|
Almahayni K, Spiekermann M, Fiore A, Yu G, Pedram K, Möckl L. Small molecule inhibitors of mammalian glycosylation. Matrix Biol Plus 2022; 16:100108. [PMID: 36467541 PMCID: PMC9713294 DOI: 10.1016/j.mbplus.2022.100108] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 02/10/2022] [Accepted: 03/10/2022] [Indexed: 01/06/2023] Open
Abstract
Glycans are one of the fundamental biopolymers encountered in living systems. Compared to polynucleotide and polypeptide biosynthesis, polysaccharide biosynthesis is a uniquely combinatorial process to which interdependent enzymes with seemingly broad specificities contribute. The resulting intracellular cell surface, and secreted glycans play key roles in health and disease, from embryogenesis to cancer progression. The study and modulation of glycans in cell and organismal biology is aided by small molecule inhibitors of the enzymes involved in glycan biosynthesis. In this review, we survey the arsenal of currently available inhibitors, focusing on agents which have been independently validated in diverse systems. We highlight the utility of these inhibitors and drawbacks to their use, emphasizing the need for innovation for basic research as well as for therapeutic applications.
Collapse
Affiliation(s)
- Karim Almahayni
- Max Planck Institute for the Science of Light, 91058 Erlangen, Germany
| | - Malte Spiekermann
- Max Planck Institute for the Science of Light, 91058 Erlangen, Germany
| | - Antonio Fiore
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Guoqiang Yu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Kayvon Pedram
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA,Corresponding authors.
| | - Leonhard Möckl
- Max Planck Institute for the Science of Light, 91058 Erlangen, Germany,Corresponding authors.
| |
Collapse
|
4
|
Laine RA. The case for re-examining glycosylation inhibitors, mimetics, primers and glycosylation decoys as antivirals and anti-inflammatories in COVID19. Glycobiology 2020; 30:763-767. [PMID: 32829416 PMCID: PMC7499584 DOI: 10.1093/glycob/cwaa083] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/20/2020] [Indexed: 12/17/2022] Open
Affiliation(s)
- Roger A Laine
- Departments of Biological Sciences and Chemistry, Louisiana State University and A&M College, Baton Rouge, LA 70803, USA
| |
Collapse
|
5
|
α-glucosidase inhibitors as host-directed antiviral agents with potential for the treatment of COVID-19. Biochem Soc Trans 2020; 48:1287-1295. [PMID: 32510142 DOI: 10.1042/bst20200505] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 04/28/2020] [Accepted: 05/11/2020] [Indexed: 01/12/2023]
Abstract
The ongoing COVID-19 pandemic, caused by SARS-CoV-2, has pushed the health systems of many countries to breaking point and precipitated social distancing measures that have crippled economic activities across the globe. A return to normality is unlikely until effective therapeutics and a vaccine are available. The immediacy of this problem suggests that drug strategies should focus on repurposing approved drugs or late-stage clinical candidates, as these have the shortest path to use in the clinic. Here, we review and discuss the role of host cell N-glycosylation pathways to virus replication and the drugs available to disrupt these pathways. In particular, we make a case for evaluation of the well-tolerated drugs miglitol, celgosivir and especially miglustat for the treatment of COVID-19.
Collapse
|
6
|
Thompson AJ, Cao L, Ma Y, Wang X, Diedrich JK, Kikuchi C, Willis S, Worth C, McBride R, Yates JR, Paulson JC. Human Influenza Virus Hemagglutinins Contain Conserved Oligomannose N-Linked Glycans Allowing Potent Neutralization by Lectins. Cell Host Microbe 2020; 27:725-735.e5. [PMID: 32298658 PMCID: PMC7158820 DOI: 10.1016/j.chom.2020.03.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 02/13/2020] [Accepted: 03/17/2020] [Indexed: 12/12/2022]
Abstract
Hemagglutinins (HAs) from human influenza viruses adapt to bind α2-6-linked sialosides, overcoming a receptor-defined species barrier distinct from the α2-3 specificity of avian virus progenitors. Additionally, human-adapted HAs gain glycosylation sites over time, although their biological function is poorly defined. Using quantitative glycomic analysis, we show that HAs from human pandemic viruses exhibit significant proportions of high-mannose type N-linked glycans throughout the head domain. By contrast, poorly adapted avian-origin HAs contain predominately complex-type glycans, which have greater structural diversity. Although oligomannose levels vary, they are present in all tested recombinant HAs and whole viruses and can be specifically targeted for universal detection. The positions of high-mannose glycosites on the HA of human H1N1 and H3N2 strains are conserved. Additionally, high-mannose-binding lectins possess a broad capacity to neutralize and prevent infection with contemporary H3N2 strains. These findings reveal the biological significance of HA glycosylation and therapeutic potential of targeting these structures.
Collapse
Affiliation(s)
- Andrew J Thompson
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA
| | - Liwei Cao
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA
| | - Yuanhui Ma
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA
| | - Xiaoning Wang
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA
| | - Jolene K Diedrich
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA
| | - Chika Kikuchi
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA
| | - Shelby Willis
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA
| | - Charli Worth
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA
| | - Ryan McBride
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA
| | - John R Yates
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA
| | - James C Paulson
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA; Department of Immunology & Microbiology, Scripps Research, La Jolla, CA 92037, USA.
| |
Collapse
|
7
|
O’Keefe S, Roebuck QP, Nakagome I, Hirono S, Kato A, Nash R, High S. Characterizing the selectivity of ER α-glucosidase inhibitors. Glycobiology 2019; 29:530-542. [PMID: 30976784 PMCID: PMC6583763 DOI: 10.1093/glycob/cwz029] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 03/15/2019] [Accepted: 04/08/2019] [Indexed: 02/06/2023] Open
Abstract
The endoplasmic reticulum (ER) contains both α-glucosidases and α-mannosidases which process the N-linked oligosaccharides of newly synthesized glycoproteins and thereby facilitate polypeptide folding and glycoprotein quality control. By acting as structural mimetics, iminosugars can selectively inhibit these ER localized α-glycosidases, preventing N-glycan trimming and providing a molecular basis for their therapeutic applications. In this study, we investigate the effects of a panel of nine iminosugars on the actions of ER luminal α-glucosidase I and α-glucosidase II. Using ER microsomes to recapitulate authentic protein N-glycosylation and oligosaccharide processing, we identify five iminosugars that selectively inhibit N-glycan trimming. Comparison of their inhibitory activities in ER microsomes against their effects on purified ER α-glucosidase II, suggests that 3,7a-diepi-alexine acts as a selective inhibitor of ER α-glucosidase I. The other active iminosugars all inhibit α-glucosidase II and, having identified 1,4-dideoxy-1,4-imino-D-arabinitol (DAB) as the most effective of these compounds, we use in silico modeling to understand the molecular basis for this enhanced activity. Taken together, our work identifies the C-3 substituted pyrrolizidines casuarine and 3,7a-diepi-alexine as promising "second-generation" iminosugar inhibitors.
Collapse
Affiliation(s)
- Sarah O’Keefe
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Quentin P Roebuck
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Izumi Nakagome
- School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan
| | - Shuichi Hirono
- School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan
| | - Atsushi Kato
- Department of Hospital Pharmacy, University of Toyama, 2630 Sugitani, Toyama, Japan
| | - Robert Nash
- PhytoQuest Ltd, Plas Gogerddan, Aberystwyth, Ceredigion, UK
| | - Stephen High
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| |
Collapse
|
8
|
Gonda J, Široký M, Martinková M, Homolya S, Vilková M, Pilátová MB, Šesták S. Synthesis and biological activity of diastereoisomeric octahydro-1H-indole-5,6,7-triols, analogues of castanospermine. Tetrahedron 2019. [DOI: 10.1016/j.tet.2018.12.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
9
|
Schröder SP, Kallemeijn WW, Debets MF, Hansen T, Sobala LF, Hakki Z, Williams SJ, Beenakker TJM, Aerts JMFG, van der Marel GA, Codée JDC, Davies GJ, Overkleeft HS. Spiro-epoxyglycosides as Activity-Based Probes for Glycoside Hydrolase Family 99 Endomannosidase/Endomannanase. Chemistry 2018; 24:9983-9992. [PMID: 29797675 PMCID: PMC6055899 DOI: 10.1002/chem.201801902] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 05/23/2018] [Indexed: 11/06/2022]
Abstract
N-Glycans direct protein function, stability, folding and targeting, and influence immunogenicity. While most glycosidases that process N-glycans cleave a single sugar residue at a time, enzymes from glycoside hydrolase family 99 are endo-acting enzymes that cleave within complex N-glycans. Eukaryotic Golgi endo-1,2-α-mannosidase cleaves glucose-substituted mannose within immature glucosylated high-mannose N-glycans in the secretory pathway. Certain bacteria within the human gut microbiota produce endo-1,2-α-mannanase, which cleaves related structures within fungal mannan, as part of nutrient acquisition. An unconventional mechanism of catalysis was proposed for enzymes of this family, hinted at by crystal structures of imino/azasugars complexed within the active site. Based on this mechanism, we developed the synthesis of two glycosides bearing a spiro-epoxide at C-2 as electrophilic trap, to covalently bind a mechanistically important, conserved GH99 catalytic residue. The spiro-epoxyglycosides are equipped with a fluorescent tag, and following incubation with recombinant enzyme, allow concentration, time and pH dependent visualization of the bound enzyme using gel electrophoresis.
Collapse
Affiliation(s)
- Sybrin P. Schröder
- Department of Bioorganic ChemistryLeiden Institute of ChemistryEinsteinweg 552333 CCLeidenThe Netherlands
| | - Wouter W. Kallemeijn
- Department of Medical BiochemistryLeiden Institute of ChemistryEinsteinweg 552333 CCLeidenThe Netherlands
| | - Marjoke F. Debets
- Department of Bioorganic ChemistryLeiden Institute of ChemistryEinsteinweg 552333 CCLeidenThe Netherlands
| | - Thomas Hansen
- Department of Bioorganic ChemistryLeiden Institute of ChemistryEinsteinweg 552333 CCLeidenThe Netherlands
| | - Lukasz F. Sobala
- Department of Chemistry, York Structural Biology LaboratoryUniversity of YorkHeslingtonYorkYO10 5DDUK
| | - Zalihe Hakki
- School of Chemistry and Bio21 Molecular Science and Biotechnology InstituteUniversity of MelbourneParkvilleVictoriaAustralia
| | - Spencer J. Williams
- School of Chemistry and Bio21 Molecular Science and Biotechnology InstituteUniversity of MelbourneParkvilleVictoriaAustralia
| | - Thomas J. M. Beenakker
- Department of Bioorganic ChemistryLeiden Institute of ChemistryEinsteinweg 552333 CCLeidenThe Netherlands
| | - Johannes M. F. G. Aerts
- Department of Medical BiochemistryLeiden Institute of ChemistryEinsteinweg 552333 CCLeidenThe Netherlands
| | - Gijsbert A. van der Marel
- Department of Bioorganic ChemistryLeiden Institute of ChemistryEinsteinweg 552333 CCLeidenThe Netherlands
| | - Jeroen D. C. Codée
- Department of Bioorganic ChemistryLeiden Institute of ChemistryEinsteinweg 552333 CCLeidenThe Netherlands
| | - Gideon J. Davies
- Department of Chemistry, York Structural Biology LaboratoryUniversity of YorkHeslingtonYorkYO10 5DDUK
| | - Herman S. Overkleeft
- Department of Bioorganic ChemistryLeiden Institute of ChemistryEinsteinweg 552333 CCLeidenThe Netherlands
| |
Collapse
|
10
|
Tyrrell BE, Sayce AC, Warfield KL, Miller JL, Zitzmann N. Iminosugars: Promising therapeutics for influenza infection. Crit Rev Microbiol 2017; 43:521-545. [PMID: 27931136 PMCID: PMC5470110 DOI: 10.1080/1040841x.2016.1242868] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 09/02/2016] [Accepted: 09/27/2016] [Indexed: 01/11/2023]
Abstract
Influenza virus causes three to five million severe respiratory infections per year in seasonal epidemics, and sporadic pandemics, three of which occurred in the twentieth century and are a continuing global threat. Currently licensed antivirals exclusively target the viral neuraminidase or M2 ion channel, and emerging drug resistance necessitates the development of novel therapeutics. It is believed that a host-targeted strategy may combat the development of antiviral drug resistance. To this end, a class of molecules known as iminosugars, hydroxylated carbohydrate mimics with the endocyclic oxygen atom replaced by a nitrogen atom, are being investigated for their broad-spectrum antiviral potential. The influenza virus glycoproteins, hemagglutinin and neuraminidase, are susceptible to inhibition of endoplasmic reticulum α-glucosidases by certain iminosugars, leading to reduced virion production or infectivity, demonstrated by in vitro and in vivo studies. In some experiments, viral strain-specific effects are observed. Iminosugars may also inhibit other host and virus targets with antiviral consequences. While investigations of anti-influenza iminosugar activities have been conducted since the 1980s, recent successes of nojirimycin derivatives have re-invigorated investigation of the therapeutic potential of iminosugars as orally available, low cytotoxicity, effective anti-influenza drugs.
Collapse
Affiliation(s)
- Beatrice Ellen Tyrrell
- Department of Biochemistry, University of Oxford Medical Sciences DivisionOxfordUnited Kingdom of Great Britain and Northern Ireland
| | - Andrew Cameron Sayce
- Department of Biochemistry, University of Oxford Medical Sciences DivisionOxfordUnited Kingdom of Great Britain and Northern Ireland
| | - Kelly Lyn Warfield
- Antiviral Research and Development, Emergent BioSolutions IncGaithersburgMDUnited States
| | - Joanna Louise Miller
- Department of Biochemistry, University of Oxford Medical Sciences DivisionOxfordUnited Kingdom of Great Britain and Northern Ireland
| | - Nicole Zitzmann
- Department of Biochemistry, University of Oxford Medical Sciences DivisionOxfordUnited Kingdom of Great Britain and Northern Ireland
| |
Collapse
|
11
|
Cheng B, Hirokami Y, Li YX, Kato A, Jia YM, Yu CY. Synthesis and glycosidase inhibition of C-7 modified casuarine derivatives. CHINESE CHEM LETT 2017. [DOI: 10.1016/j.cclet.2017.06.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
12
|
|
13
|
Srinivasan B, Zhou H, Mitra S, Skolnick J. Novel small molecule binders of human N-glycanase 1, a key player in the endoplasmic reticulum associated degradation pathway. Bioorg Med Chem 2016; 24:4750-4758. [PMID: 27567076 DOI: 10.1016/j.bmc.2016.08.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 08/08/2016] [Accepted: 08/12/2016] [Indexed: 12/30/2022]
Abstract
Peptide:N-glycanase (NGLY1) is an enzyme responsible for cleaving oligosaccharide moieties from misfolded glycoproteins to enable their proper degradation. Deletion and truncation mutations in this gene are responsible for an inherited disorder of the endoplasmic reticulum-associated degradation pathway. However, the literature is unclear whether the disorder is a result of mutations leading to loss-of-function, loss of substrate specificity, loss of protein stability or a combination of these factors. In this communication, without burdening ourselves with the mechanistic underpinning of disease causation because of mutations on the NGLY1 protein, we demonstrate the successful application of virtual ligand screening (VLS) combined with experimental high-throughput validation to the discovery of novel small-molecules that show binding to the transglutaminase domain of NGLY1. Attempts at recombinant expression and purification of six different constructs led to successful expression of five, with three constructs purified to homogeneity. Most mutant variants failed to purify possibly because of misfolding and the resultant exposure of surface hydrophobicity that led to protein aggregation. For the purified constructs, our threading/structure-based VLS algorithm, FINDSITE(comb), was employed to predict ligands that may bind to the protein. Then, the predictions were assessed by high-throughput differential scanning fluorimetry. This led to the identification of nine different ligands that bind to the protein of interest and provide clues to the nature of pharmacophore that facilitates binding. This is the first study that has identified novel ligands that bind to the NGLY1 protein as a possible starting point in the discovery of ligands with potential therapeutic applications in the treatment of the disorder caused by NGLY1 mutants.
Collapse
Affiliation(s)
- Bharath Srinivasan
- Center for the Study of Systems Biology, School of Biology, Georgia Institute of Technology, 950, Atlantic Drive, Atlanta, GA 30332, United States.
| | - Hongyi Zhou
- Center for the Study of Systems Biology, School of Biology, Georgia Institute of Technology, 950, Atlantic Drive, Atlanta, GA 30332, United States
| | - Sreyoshi Mitra
- Center for the Study of Systems Biology, School of Biology, Georgia Institute of Technology, 950, Atlantic Drive, Atlanta, GA 30332, United States
| | - Jeffrey Skolnick
- Center for the Study of Systems Biology, School of Biology, Georgia Institute of Technology, 950, Atlantic Drive, Atlanta, GA 30332, United States.
| |
Collapse
|
14
|
Taylor DL, Nash R, Fellows LE, Kang MS, Tyms AS. Naturally Occurring Pyrrolizidines: Inhibition of α-Glucosidase 1 and Anti-HIV Activity of One Stereoisomer. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/095632029200300504] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Alexine, a naturally occurring pyrrolizidine alkaloid, isolated from Alexa leiopetala, and four stereoisomers, isolated from Castanospermum australe, were investigated for inhibitory activity against the growth of HIV-1. Only treatment with the 7,7a-diepialexine restricted virus growth (IC50 0.38 mm) although it was less active than the indolizidine alkaloid castanospermine (IC50 0.02 mm). The antiviral effects of 7,7a-diepialexine, like castanospermine, correlated with the inhibitory activity against purified pig kidney α-glucosidase 1 of the glycoprotein processing enzymes and the reduced cleavage of the precursor HIV-1 glycoprotein gp160.
Collapse
Affiliation(s)
- D. L. Taylor
- MRC Collaborative Centre, 1-3 Burtonhole Lane, Mill Hill, London NW7 1AD, UK
| | - R. Nash
- Royal Botanic Gardens, Kew, Surrey TW9 3DS, UK
| | | | - M. S. Kang
- Marion Merrell Dow Research Institute, Cincinnati, OH, USA
| | - A. S. Tyms
- MRC Collaborative Centre, 1-3 Burtonhole Lane, Mill Hill, London NW7 1AD, UK
| |
Collapse
|
15
|
Sayce AC, Alonzi DS, Killingbeck SS, Tyrrell BE, Hill ML, Caputo AT, Iwaki R, Kinami K, Ide D, Kiappes JL, Beatty PR, Kato A, Harris E, Dwek RA, Miller JL, Zitzmann N. Iminosugars Inhibit Dengue Virus Production via Inhibition of ER Alpha-Glucosidases--Not Glycolipid Processing Enzymes. PLoS Negl Trop Dis 2016; 10:e0004524. [PMID: 26974655 PMCID: PMC4790851 DOI: 10.1371/journal.pntd.0004524] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 02/17/2016] [Indexed: 11/18/2022] Open
Abstract
It has long been thought that iminosugar antiviral activity is a function of inhibition of endoplasmic reticulum-resident α-glucosidases, and on this basis, many iminosugars have been investigated as therapeutic agents for treatment of infection by a diverse spectrum of viruses, including dengue virus (DENV). However, iminosugars are glycomimetics possessing a nitrogen atom in place of the endocyclic oxygen atom, and the ubiquity of glycans in host metabolism suggests that multiple pathways can be targeted via iminosugar treatment. Successful treatment of patients with glycolipid processing defects using iminosugars highlights the clinical exploitation of iminosugar inhibition of enzymes other than ER α-glucosidases. Evidence correlating antiviral activity with successful inhibition of ER glucosidases together with the exclusion of alternative mechanisms of action of iminosugars in the context of DENV infection is limited. Celgosivir, a bicyclic iminosugar evaluated in phase Ib clinical trials as a therapeutic for the treatment of DENV infection, was confirmed to be antiviral in a lethal mouse model of antibody-enhanced DENV infection. In this study we provide the first evidence of the antiviral activity of celgosivir in primary human macrophages in vitro, in which it inhibits DENV secretion with an EC50 of 5 μM. We further demonstrate that monocyclic glucose-mimicking iminosugars inhibit isolated glycoprotein and glycolipid processing enzymes and that this inhibition also occurs in primary cells treated with these drugs. By comparison to bicyclic glucose-mimicking iminosugars which inhibit glycoprotein processing but do not inhibit glycolipid processing and galactose-mimicking iminosugars which do not inhibit glycoprotein processing but do inhibit glycolipid processing, we demonstrate that inhibition of endoplasmic reticulum-resident α-glucosidases, not glycolipid processing, is responsible for iminosugar antiviral activity against DENV. Our data suggest that inhibition of ER α-glucosidases prevents release of virus and is the primary antiviral mechanism of action of iminosugars against DENV. Current treatment of dengue virus infection is supportive; however, iminosugars have been widely investigated as an antiviral strategy. The means by which these molecules are thought to exert their antiviral effects is through inhibition of host-resident glycoprotein processing enzymes, the endoplasmic reticulum-resident α-glucosidases, but many iminosugars are also capable of inhibiting host glycolipid processing and are utilized clinically for the treatment of lysosomal storage disorders such as Gaucher’s and Niemann-Pick type C diseases. The work presented here is the first to conclusively differentiate the antiviral properties of these two major mechanisms of action of iminosugars, and our data support the long-standing hypothesis that inhibition of glycoprotein processing is the essential antiviral property of iminosugars in the case of dengue virus infection. These results indicate that further development of iminosugars as dengue antivirals should focus on optimization of glycoprotein inhibition efficacy with reduction or elimination of glycolipid modulating properties to minimize off-target effects. These results are supported by the in vitro and in vivo efficacy of the bicyclic iminosugar, celgosivir, which we demonstrate to lack capacity for inhibition of glycosphingolipid processing.
Collapse
Affiliation(s)
- Andrew C. Sayce
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Dominic S. Alonzi
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Sarah S. Killingbeck
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California-Berkeley, Berkeley, California, United States of America
| | - Beatrice E. Tyrrell
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Michelle L. Hill
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Alessandro T. Caputo
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Ren Iwaki
- Department of Hospital Pharmacy, University of Toyama, Toyama, Japan
| | - Kyoko Kinami
- Department of Hospital Pharmacy, University of Toyama, Toyama, Japan
| | - Daisuke Ide
- Department of Hospital Pharmacy, University of Toyama, Toyama, Japan
| | - J. L. Kiappes
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - P. Robert Beatty
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California-Berkeley, Berkeley, California, United States of America
| | - Atsushi Kato
- Department of Hospital Pharmacy, University of Toyama, Toyama, Japan
| | - Eva Harris
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California-Berkeley, Berkeley, California, United States of America
| | - Raymond A. Dwek
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Joanna L. Miller
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, Oxford, United Kingdom
- * E-mail: (JLM); (NZ)
| | - Nicole Zitzmann
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, Oxford, United Kingdom
- * E-mail: (JLM); (NZ)
| |
Collapse
|
16
|
Warfield KL, Barnard DL, Enterlein SG, Smee DF, Khaliq M, Sampath A, Callahan MV, Ramstedt U, Day CW. The Iminosugar UV-4 is a Broad Inhibitor of Influenza A and B Viruses ex Vivo and in Mice. Viruses 2016; 8:71. [PMID: 27072420 PMCID: PMC4810261 DOI: 10.3390/v8030071] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 02/11/2016] [Accepted: 02/16/2016] [Indexed: 12/02/2022] Open
Abstract
Iminosugars that are competitive inhibitors of endoplasmic reticulum (ER) α-glucosidases have been demonstrated to have antiviral activity against a diverse set of viruses. A novel iminosugar, UV-4B, has recently been shown to provide protection against lethal infections with dengue and influenza A (H1N1) viruses in mice. In the current study, the breadth of activity of UV-4B against influenza was examined ex vivo and in vivo. Efficacy of UV-4B against influenza A and B viruses was shown in primary human bronchial epithelial cells, a principal target tissue for influenza. Efficacy of UV-4B against influenza A (H1N1 and H3N2 subtypes) and influenza B was demonstrated using multiple lethal mouse models with readouts including mortality and weight loss. Clinical trials are ongoing to demonstrate safety of UV-4B and future studies to evaluate antiviral activity against influenza in humans are planned.
Collapse
Affiliation(s)
| | - Dale L Barnard
- Institute for Antiviral Research, Utah State University, Logan, UT 84322-5600, USA.
| | | | - Donald F Smee
- Institute for Antiviral Research, Utah State University, Logan, UT 84322-5600, USA.
| | | | | | - Michael V Callahan
- Division of Infectious Diseases, Massachusetts General Hospital/Harvard Medical School, Boston, MA 02114, USA.
- Unither Virology, LLC, Silver Spring, MD 20910, USA.
| | | | - Craig W Day
- Institute for Antiviral Research, Utah State University, Logan, UT 84322-5600, USA.
| |
Collapse
|
17
|
Warfield KL, Plummer E, Alonzi DS, Wolfe GW, Sampath A, Nguyen T, Butters TD, Enterlein SG, Stavale EJ, Shresta S, Ramstedt U. A Novel Iminosugar UV-12 with Activity against the Diverse Viruses Influenza and Dengue (Novel Iminosugar Antiviral for Influenza and Dengue). Viruses 2015; 7:2404-27. [PMID: 25984714 PMCID: PMC4452912 DOI: 10.3390/v7052404] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 05/07/2015] [Indexed: 12/30/2022] Open
Abstract
Iminosugars are capable of targeting the life cycles of multiple viruses by blocking host endoplasmic reticulum α-glucosidase enzymes that are required for competent replication of a variety of enveloped, glycosylated viruses. Iminosugars as a class are approved for use in humans with diseases such as diabetes and Gaucher’s disease, providing evidence for safety of this class of compounds. The in vitro antiviral activity of iminosugars has been described in several publications with a subset of these demonstrating in vivo activity against flaviviruses, herpesviruses, retroviruses and filoviruses. Although there is compelling non-clinical in vivo evidence of antiviral efficacy, the efficacy of iminosugars as antivirals has yet to be demonstrated in humans. In the current study, we report a novel iminosugar, UV-12, which has efficacy against dengue and influenza in mouse models. UV-12 exhibits drug-like properties including oral bioavailability and good safety profile in mice and guinea pigs. UV-12 is an example of an iminosugar with activity against multiple virus families that should be investigated in further safety and efficacy studies and demonstrates potential value of this drug class as antiviral therapeutics.
Collapse
Affiliation(s)
| | - Emily Plummer
- La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037, USA.
| | | | | | | | - Tam Nguyen
- Tam Nguyen LLC, Gaithersburg, MD 20879, USA.
| | | | | | - Eric J Stavale
- Integrated Biotherapeutics, Gaithersburg, MD 20878, USA.
| | - Sujan Shresta
- La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037, USA.
| | | |
Collapse
|
18
|
In vivo therapeutic protection against influenza A (H1N1) oseltamivir-sensitive and resistant viruses by the iminosugar UV-4. PLoS One 2015; 10:e0121662. [PMID: 25786028 PMCID: PMC4364785 DOI: 10.1371/journal.pone.0121662] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 02/02/2015] [Indexed: 01/26/2023] Open
Abstract
Our lead iminosugar analog called UV-4 or N-(9-methoxynonyl)-1-deoxynojirimycin inhibits activity of endoplasmic reticulum (ER) α-glucosidases I and II and is a potent, host-targeted antiviral candidate. The mechanism of action for the antiviral activity of iminosugars is proposed to be inhibition of ER α-glucosidases leading to misfolding of critical viral glycoproteins. These misfolded glycoproteins would then be incorporated into defective virus particles or targeted for degradation resulting in a reduction of infectious progeny virions. UV-4, and its hydrochloride salt known as UV-4B, is highly potent against dengue virus in vitro and promotes complete survival in a lethal dengue virus mouse model. In the current studies, UV-4 was shown to be highly efficacious via oral gavage against both oseltamivir-sensitive and -resistant influenza A (H1N1) infections in mice even if treatment was initiated as late as 48-72 hours after infection. The minimal effective dose was found to be 80-100 mg/kg when administered orally thrice daily. UV-4 treatment did not affect the development of protective antibody responses after either influenza infection or vaccination. Therefore, UV-4 is a promising candidate for further development as a therapeutic intervention against influenza.
Collapse
|
19
|
Kato A, Hirokami Y, Kinami K, Tsuji Y, Miyawaki S, Adachi I, Hollinshead J, Nash RJ, Kiappes JL, Zitzmann N, Cha JK, Molyneux RJ, Fleet GWJ, Asano N. Isolation and SAR studies of bicyclic iminosugars from Castanospermum australe as glycosidase inhibitors. PHYTOCHEMISTRY 2015; 111:124-131. [PMID: 25583438 DOI: 10.1016/j.phytochem.2014.12.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 12/04/2014] [Accepted: 12/11/2014] [Indexed: 06/04/2023]
Abstract
We report the isolation and structural determination of fourteen iminosugars, containing five pyrrolizidines and five indolizidines, from Castanospermum australe. The structure of a new alkaloid was elucidated by spectroscopic methods as 6,8-diepi-castanospermine (13). Our side-by-side comparison between bicyclic and corresponding monocyclic iminosugars revealed that inhibition potency and spectrum against each enzyme are clearly changed by their core structures. Castanospermine (10) and 1-deoxynojirimycin (DNJ) have a common d-gluco configuration, and they showed the expected similar inhibition potency and spectrum. In sharp contrast, 6-epi-castanospermine (12) and 1-deoxymannojirimycin (manno-DNJ) both have the d-manno configuration but the α-mannosidase inhibition of 6-epi-castanospermine (12) was much better than that of manno-DNJ. 6,8-Diepi-castanospermine (13) could be regarded as a bicyclic derivative of talo-DNJ, but it showed a complete loss of α-galactosidase A inhibition. This behavior against α-galactosidase A is similar to that observed for 1-epi-australine (6) and altro-DMDP.
Collapse
Affiliation(s)
- Atsushi Kato
- Department of Hospital Pharmacy, University of Toyama, Toyama 930-0194, Japan.
| | - Yuki Hirokami
- Department of Hospital Pharmacy, University of Toyama, Toyama 930-0194, Japan
| | - Kyoko Kinami
- Department of Hospital Pharmacy, University of Toyama, Toyama 930-0194, Japan
| | - Yutaro Tsuji
- Department of Hospital Pharmacy, University of Toyama, Toyama 930-0194, Japan
| | - Shota Miyawaki
- Department of Hospital Pharmacy, University of Toyama, Toyama 930-0194, Japan
| | - Isao Adachi
- Department of Hospital Pharmacy, University of Toyama, Toyama 930-0194, Japan
| | - Jackie Hollinshead
- Institute of Biological, Environmental and Rural Sciences/Phytoquest Limited, Plas Gogerddan, Aberystwyth, Ceredigion SY23 3EB, United Kingdom
| | - Robert J Nash
- Institute of Biological, Environmental and Rural Sciences/Phytoquest Limited, Plas Gogerddan, Aberystwyth, Ceredigion SY23 3EB, United Kingdom
| | - J L Kiappes
- Oxford Glycobiology Institute, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Nicole Zitzmann
- Oxford Glycobiology Institute, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Jin K Cha
- Department of Chemistry, Wayne State University, 5101 Cass Ave, Detroit, MI 48202, United States
| | - Russell J Molyneux
- Daniel K. Inouye College of Pharmacy, University of Hawaii at Hilo, 34 Rainbow Drive, Hilo, HI 96720, United States
| | - George W J Fleet
- Oxford Glycobiology Institute, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom; Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom.
| | - Naoki Asano
- BioApply Co., Ltd., 1-95 Tsuchishimizu, Kanazawa 920-0955, Japan
| |
Collapse
|
20
|
Martinez JP, Sasse F, Brönstrup M, Diez J, Meyerhans A. Antiviral drug discovery: broad-spectrum drugs from nature. Nat Prod Rep 2015; 32:29-48. [PMID: 25315648 DOI: 10.1039/c4np00085d] [Citation(s) in RCA: 128] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Covering: up to April 2014. The development of drugs with broad-spectrum antiviral activities is a long pursued goal in drug discovery. It has been shown that blocking co-opted host-factors abrogates the replication of many viruses, yet the development of such host-targeting drugs has been met with scepticism mainly due to toxicity issues and poor translation to in vivo models. With the advent of new and more powerful screening assays and prediction tools, the idea of a drug that can efficiently treat a wide range of viral infections by blocking specific host functions has re-bloomed. Here we critically review the state-of-the-art in broad-spectrum antiviral drug discovery. We discuss putative targets and treatment strategies, with particular focus on natural products as promising starting points for antiviral lead development.
Collapse
Affiliation(s)
- J P Martinez
- Infection Biology Group, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain.
| | | | | | | | | |
Collapse
|
21
|
Tiwari DK, Bharadwaj KC, Puranik VG, Tiwari DK. Divergent total synthesis of 1,6,8a-tri-epi-castanospermine and 1-deoxy-6,8a-di-epi-castanospermine from substituted azetidin-2-one (β-lactam), involving a cascade sequence of reactions as a key step. Org Biomol Chem 2014; 12:7389-96. [PMID: 25134486 DOI: 10.1039/c4ob00948g] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A divergent, short, and novel total synthesis of 1,6,8a-tri-epi-castanospermine (7) and 1-deoxy-6,8a-di-epi-castanospermine (8) has been developed via a common precursor, 15, obtained from D-mannitol derived β-lactam. The key step involves a one pot cascade sequence of trimethyl sulfoxonium ylide based cyclization of epoxy sulfonamide 14via epoxide ring opening, one carbon homologation followed by intramolecular cyclization.
Collapse
Affiliation(s)
- Dipak Kumar Tiwari
- Division of Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology, Tarnaka, Hyderabad-500007, India.
| | | | | | | |
Collapse
|
22
|
Hussain S, Miller JL, Harvey DJ, Gu Y, Rosenthal PB, Zitzmann N, McCauley JW. Strain-specific antiviral activity of iminosugars against human influenza A viruses. J Antimicrob Chemother 2014; 70:136-52. [PMID: 25223974 PMCID: PMC4267503 DOI: 10.1093/jac/dku349] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Objectives Drugs that target host cell processes can be employed to complement drugs that specifically target viruses, and iminosugar compounds that inhibit host α-glucosidases have been reported to show antiviral activity against multiple viruses. Here the effect and mechanism of two iminosugar α-glucosidase inhibitors, N-butyl-deoxynojirimycin (NB-DNJ) and N-nonyl-deoxynojirimycin (NN-DNJ), on human influenza A viruses was examined. Methods The viruses examined were a recently circulating seasonal influenza A(H3N2) virus strain A/Brisbane/10/2007, an older H3N2 strain A/Udorn/307/72, and A/Lviv/N6/2009, a strain representative of the currently circulating pandemic influenza A(H1N1)pdm09 virus. Results The inhibitors had the strongest effect on Brisbane/10 and NN-DNJ was more potent than NB-DNJ. Both compounds showed antiviral activity in cell culture against three human influenza A viruses in a strain-specific manner. Consistent with its action as an α-glucosidase inhibitor, NN-DNJ treatment resulted in an altered glycan processing of influenza haemagglutinin (HA) and neuraminidase (NA), confirmed by MS. NN-DNJ treatment was found to reduce the cell surface expression of the H3 subtype HA. The level of sialidase activity of NA was reduced in infected cells, but the addition of exogenous sialidase to the cells did not complement the NN-DNJ-mediated inhibition of virus replication. Using reassortant viruses, the drug susceptibility profile was determined to correlate with the origin of the HA. Conclusions NN-DNJ inhibits influenza A virus replication in a strain-specific manner that is dependent on the HA.
Collapse
Affiliation(s)
- S Hussain
- Division of Virology, Medical Research Council National Institute for Medical Research, Mill Hill, London NW7 1AA, UK Division of Physical Biochemistry, Medical Research Council National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - J L Miller
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - D J Harvey
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK Department of Biological Sciences, Gibbet Hill Campus, University of Warwick, Coventry CV4 7AL, UK
| | - Y Gu
- Confocal Imaging and Analysis Laboratory, Medical Research Council National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - P B Rosenthal
- Division of Physical Biochemistry, Medical Research Council National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - N Zitzmann
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - J W McCauley
- Division of Virology, Medical Research Council National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| |
Collapse
|
23
|
Castanospermine-a plant growth regulator. J Chem Ecol 2013; 14:1467-73. [PMID: 24276397 DOI: 10.1007/bf01012418] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/1987] [Accepted: 08/17/1987] [Indexed: 10/25/2022]
Abstract
Castanospermine, 1,6,7,8-tetrahydroxyoctahydroindolizine, has been shown to be a potent dicot phytotoxin. The effective concentration to inhibit root length elongation of dicot roots by 50% is 300 ppb, while the effective concentration against monocot roots is 200 ppm, i.e., 10(3) times less effective. In contrast swainsonine, 1,2,8-trihydroxyoctahydroindolizidine, is ineffective as an inhibitor of root length elongation.
Collapse
|
24
|
Poncet-Montange G, St Martin SJ, Bogatova OV, Prusiner SB, Shoichet BK, Ghaemmaghami S. A survey of antiprion compounds reveals the prevalence of non-PrP molecular targets. J Biol Chem 2011; 286:27718-28. [PMID: 21610081 DOI: 10.1074/jbc.m111.234393] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Prion diseases are fatal neurodegenerative diseases caused by the accumulation of the misfolded isoform (PrP(Sc)) of the prion protein (PrP(C)). Cell-based screens have identified several compounds that induce a reduction in PrP(Sc) levels in infected cultured cells. However, the molecular targets of most antiprion compounds remain unknown. We undertook a large-scale, unbiased, cell-based screen for antiprion compounds and then investigated whether a representative subset of the active molecules had measurable affinity for PrP, increased the susceptibility of PrP(Sc) to proteolysis, or altered the cellular localization or expression level of PrP(C). None of the antiprion compounds showed in vitro affinity for PrP or had the ability to disaggregate PrP(Sc) in infected brain homogenates. These observations suggest that most antiprion compounds identified in cell-based screens deploy their activity via non-PrP targets in the cell. Our findings indicate that in comparison to PrP conformers themselves, proteins that play auxiliary roles in prion propagation may be more effective targets for future drug discovery efforts.
Collapse
|
25
|
|
26
|
|
27
|
Bowen EG, Wardrop DJ. Diastereoselective nitrenium ion-mediated cyclofunctionalization: total synthesis of (+)-castanospermine. Org Lett 2010; 12:5330-3. [PMID: 20964285 DOI: 10.1021/ol102371x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The asymmetric total synthesis of the α-glucosidase inhibitor (+)-castanospermine is reported. The central theme in our approach to this polyhydroxylated alkaloid is the simultaneous generation of the piperidine ring and the C-1/8a erythro stereodiad through the diastereoselective, oxamidation of an unsaturated O-alkyl hydroxamate. This process is believed to proceed sequentially via singlet acylnitrenium and aziridinium ion intermediates.
Collapse
Affiliation(s)
- Edward G Bowen
- Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607-7061, United States
| | | |
Collapse
|
28
|
Ge H, Wang YF, Xu J, Gu Q, Liu HB, Xiao PG, Zhou J, Liu Y, Yang Z, Su H. Anti-influenza agents from Traditional Chinese Medicine. Nat Prod Rep 2010; 27:1758-80. [PMID: 20941447 DOI: 10.1039/c0np00005a] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Hu Ge
- Research Center for Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-Sen University, 132 East Circle Road at University City, Guangzhou, 510006, China
| | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
|
30
|
Yi-Ming X, Wei-Shan Z. Asymmetric total synthesis of (+)-1-deoxy-6-epi-castanospermine. CHINESE J CHEM 2010. [DOI: 10.1002/cjoc.19980160107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
31
|
Ghaemmaghami S, Ullman J, Ahn M, St Martin S, Prusiner SB. Chemical induction of misfolded prion protein conformers in cell culture. J Biol Chem 2009; 285:10415-23. [PMID: 19955177 DOI: 10.1074/jbc.m109.045112] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Prion-infected cells accumulate a heterogeneous population of aberrantly folded PrP conformers, including the disease-causing isoform (PrP(Sc)). We found that specific chemicals can modulate the levels of various PrP conformers in cultured cells. Positively charged polyamidoamines (dendrimers) eliminated protease-resistant (r) PrP(Sc) from prion-infected cells and induced the formation of insoluble, protease-sensitive PrP aggregates (designated PrP(A)). Larger, positively charged polyamidoamines more efficaciously induced the formation of PrP(A) and cleared rPrP(Sc), whereas negatively charged polyamidoamines neither induced PrP(A) nor cleared rPrP(Sc). Although the biochemical properties of PrP(A) were shown to be similar to protease-sensitive (s) PrP(Sc), bioassays of PrP(A) indicated that it is not infectious. Our studies argue that PrP(A) represents an aggregated PrP species that is off-pathway relative to the formation of rPrP(Sc). It remains to be established whether the formation of PrP(A) inhibits the formation of rPrP(Sc) by sequestering PrP(C) in the form of benign, insoluble aggregates.
Collapse
Affiliation(s)
- Sina Ghaemmaghami
- Institute for Neurodegenerative Diseases, University of California, San Francisco, California 94143, USA
| | | | | | | | | |
Collapse
|
32
|
Promotion of IL-4- and IL-5-dependent differentiation of anti-mu-primed B cells by ascorbic acid 2-glucoside. Immunol Lett 2009; 122:219-26. [PMID: 19201381 DOI: 10.1016/j.imlet.2009.01.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Revised: 01/05/2009] [Accepted: 01/18/2009] [Indexed: 11/23/2022]
Abstract
The stable ascorbic acid derivative 2-O-alpha-D-glucopyranosyl-L-ascorbic acid (AA-2G) was used to investigate the role of ascorbic acid (AA) in B cell differentiation in vitro. AA-2G is stable in a solution unlike AA but is hydrolyzed by cellular alpha-glucosidase to release AA. Mouse spleen B cells were primed for 2 days with an anti-mu antibody in the presence of interleukin (IL)-4 and IL-5 and then washed and recultured with AA-2G in the presence of IL-4 and IL-5. AA-2G, but not AA, dose-dependently increased IgM production, the greatest enhancement being 150% at concentrations of more than 0.5mM. In the absence of IL-4 and IL-5, primed B cells produced a negligible amount of IgM, and AA-2G had no effect. AA-2G-induced IgM production in the presence of IL-4 and IL-5 was inhibited by the alpha-glucosidase inhibitor castanospermine. Intracellular AA content, depleted during the priming period, increased by adding AA-2G at the start of reculture. Treatment of B cells with AA-2G resulted in an increase in the number of IgM-secreting cells, CD138-positive cells and CD45R/B220-negative cells. The number of viable cells in untreated cultures decreased gradually, but the decrease was significantly attenuated by AA-2G, resulting in about 70% more viable cells in AA-2G-treated cultures. AA-2G caused a slight but reproducible enhancement of DNA synthesis and a slight decrease in the number of cells with a sub-G1 DNA content. These results demonstrated that AA released from AA-2G enhanced cytokine-dependent IgM production in anti-mu-primed B cells and suggest that its effect is caused through promoting the differentiation of B cells to plasma cells and attenuating the gradual decrease in the number of viable cells.
Collapse
|
33
|
Abstract
Treatment of cells with inhibitors of the enzymes that synthesize N-linked oligosaccharide chains results in production of glycoproteins containing missing or altered chains. This approach is useful for examining potential functional role(s) of this class of oligosaccharides on specific proteins or intact cells. This unit describes the use of inhibitors to prevent N-linked glycosylation of proteins in cultured cells. First, the optimal concentration of inhibitor for the experiment (i.e., highest nontoxic concentration) is determined by monitoring [(35)S]methionine incorporation as a measure of protein biosynthesis. The ability of the inhibitor to hinder oligosaccharide processing is then determined by analyzing cells labeled with [(3)H]mannose using TCA precipitation or endo H digestion. Further suggestions are given on how to use methods for identifying a specific glycoprotein (if available) to measure the effect of the inhibitor on its N-linked oligosaccharide chains. A Support Protocol details a method for concentrating proteins by acetone precipitation.
Collapse
Affiliation(s)
- L D Powell
- University of California San Diego, La Jolla, California, USA
| |
Collapse
|
34
|
|
35
|
Abstract
Treatment of cells with inhibitors of the enzymes that synthesize N-linked oligosaccharide chains results in production of glycoproteins containing missing or altered chains. This approach is useful for examining potential functional role(s) of this class of oligosaccharides on specific proteins or intact cells. This unit describes the use of inhibitors to prevent N-linked glycosylation of proteins in cultured cells. First, the optimal concentration of inhibitor for the experiment (i.e., highest nontoxic concentration) is determined by monitoring [35S]methionine incorporation as a measure of protein biosynthesis. The inhibitor's ability to inhibit oligosaccharide processing is then determined by analyzing cells labeled with [(H)H]mannose using TCA precipitation or endo H digestion (UNIT 13). Further suggestions are given on how to use methods for identifying a specific glycoprotein (if available) to measure the effect of the inhibitor on its N-linked oligosaccharide chains. A support protocol details a method for concentrating proteins by acetone precipitation.
Collapse
Affiliation(s)
- L D Powell
- University of California San Diego, La Jolla, California, USA
| |
Collapse
|
36
|
Abstract
The phenotypic effect of prions on host cells is influenced by the physical properties of the prion strain and its level of accumulation. In mammalian cell cultures, prion accumulation is determined by the interplay between de novo prion formation, catabolism, cell division, and horizontal cell-to-cell transmission. Understanding this dynamic enables the analytical modeling of protein-based heritability and infectivity. Here, we quantitatively measured these competing effects in a subline of neuroblastoma (N2a) cells and propose a concordant reaction mechanism to explain the kinetics of prion propagation. Our results show that cell division leads to a predictable reduction in steady-state prion levels but not to complete clearance. Scrapie-infected N2a cells were capable of accumulating different steady-state levels of prions, dictated partly by the rate of cell division. We also show that prions in this subline of N2a cells are transmitted primarily from mother to daughter cells, rather than horizontal cell-to-cell transmission. We quantitatively modeled our kinetic results based on a mechanism that assumes a subpopulation of prions is capable of self-catalysis, and the levels of this subpopulation reach saturation in fully infected cells. Our results suggest that the apparent effectiveness of antiprion compounds in culture may be strongly influenced by the growth phase of the target cells.
Collapse
|
37
|
Carroll JD, Pastuszak I, Edavana VK, Pan YT, Elbein AD. A novel trehalase from Mycobacterium smegmatis − purification, properties, requirements. FEBS J 2007; 274:1701-14. [PMID: 17319935 DOI: 10.1111/j.1742-4658.2007.05715.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Trehalose is a nonreducing disaccharide of glucose (alpha,alpha-1,1-glucosyl-glucose) that is essential for growth and survival of mycobacteria. These organisms have three different biosynthetic pathways to produce trehalose, and mutants devoid of all three pathways require exogenous trehalose in the medium in order to grow. Mycobacterium smegmatis and Mycobacterium tuberculosis also have a trehalase that may be important in controlling the levels of intracellular trehalose. In this study, we report on the purification and characterization of the trehalase from M. smegmatis, and its comparison to the trehalase from M. tuberculosis. Although these two enzymes have over 85% identity throughout their amino acid sequences, and both show an absolute requirement for inorganic phosphate for activity, the enzyme from M. smegmatis also requires Mg(2+) for activity, whereas the M. tuberculosis trehalase does not require Mg(2+). The requirement for phosphate is unusual among glycosyl hydrolases, but we could find no evidence for a phosphorolytic cleavage, or for any phosphorylated intermediates in the reaction. However, as inorganic phosphate appears to bind to, and also to greatly increase the heat stability of, the trehalase, the function of the phosphate may involve stabilizing the protein conformation and/or initiating protein aggregation. Sodium arsenate was able to substitute to some extent for the sodium phosphate requirement, whereas inorganic pyrophosphate and polyphosphates were inhibitory. The purified trehalase showed a single 71 kDa band on SDS gels, but active enzyme eluted in the void volume of a Sephracryl S-300 column, suggesting a molecular mass of about 1500 kDa or a multimer of 20 or more subunits. The trehalase is highly specific for alpha,alpha-trehalose and did not hydrolyze alpha,beta-trelalose or beta,beta-trehalose, trehalose dimycolate, or any other alpha-glucoside or beta-glucoside. Attempts to obtain a trehalase-negative mutant of M. smegmatis have been unsuccessful, although deletions of other trehalose metabolic enzymes have yielded viable mutants. This suggests that trehalase is an essential enzyme for these organisms. The enzyme has a pH optimum of 7.1, and is active in various buffers, as long as inorganic phosphate and Mg(2+) are present. Glucose was the only product produced by the trehalase in the presence of either phosphate or arsenate.
Collapse
Affiliation(s)
- J David Carroll
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | | | | | | | | |
Collapse
|
38
|
|
39
|
Napier SL, Healy ZR, Schnaar RL, Konstantopoulos K. Selectin Ligand Expression Regulates the Initial Vascular Interactions of Colon Carcinoma Cells. J Biol Chem 2007; 282:3433-41. [PMID: 17135256 DOI: 10.1074/jbc.m607219200] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Selectin-mediated binding of tumor cells to platelets, leukocytes, and vascular endothelium may regulate their hematogenous spread in the microvasculature. We recently reported that CD44 variant isoforms (CD44v) on LS174T colon carcinoma cells possess selectin binding activity. Here we extended those findings by showing that T84 and Colo205 colon carcinoma cells bind selectins via sialidase-sensitive O-linked glycans presented on CD44v, independent of heparan and chondroitin sulfate. To assess the functional role of CD44v in selectin-mediated binding, we quantified the adhesion to selectins of T84 cell subpopulations sorted based on their CD44 expression levels and stable LS174T cell lines generated using CD44 short hairpin RNA. High versus low CD44-expressing T84 cells tethered more efficiently to P- and L-selectin, but not E-selectin, and rolled more slowly on P- and E-selectin. Knocking down CD44 expression on LS174T cells inhibited binding to P-selectin and increased rolling velocities over P- and L-selectin relative to control-transfected cells, without affecting tethering and rolling on E-selectin, however. Blot rolling analysis revealed the presence of alternative sialylated glycoproteins with molecular masses of approximately 170 and approximately 130 kDa, which can mediate selectin binding in CD44-knockdown cells. Heparin diminishes the avidity of colon carcinoma cells for P- and L-selectin, which may compromise integrin-mediated firm adhesion to host cells and mitigate metastasis. Our finding that CD44v is a functional P-selectin ligand on colon carcinoma provides a novel perspective on the enhanced metastatic potential associated with tumor CD44v overexpression and the role of selectins in metastasis.
Collapse
Affiliation(s)
- Susan L Napier
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | | | | | | |
Collapse
|
40
|
G. West F, A. Vanecko J. Survey of Chemical Syntheses of the Pyrrolizidine Alkaloids Turneforcidine and Platynecine. HETEROCYCLES 2007. [DOI: 10.3987/rev-07-sr(w)5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
41
|
|
42
|
Whitby K, Pierson TC, Geiss B, Lane K, Engle M, Zhou Y, Doms RW, Diamond MS. Castanospermine, a potent inhibitor of dengue virus infection in vitro and in vivo. J Virol 2005; 79:8698-706. [PMID: 15994763 PMCID: PMC1168722 DOI: 10.1128/jvi.79.14.8698-8706.2005] [Citation(s) in RCA: 210] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Previous studies have suggested that alpha-glucosidase inhibitors such as castanospermine and deoxynojirimycin inhibit dengue virus type 1 infection by disrupting the folding of the structural proteins prM and E, a step crucial to viral secretion. We extend these studies by evaluating the inhibitory activity of castanospermine against a panel of clinically important flaviviruses including all four serotypes of dengue virus, yellow fever virus, and West Nile virus. Using in vitro assays we demonstrated that infections by all serotypes of dengue virus were inhibited by castanospermine. In contrast, yellow fever virus and West Nile virus were partially and almost completely resistant to the effects of the drug, respectively. Castanospermine inhibited dengue virus infection at the level of secretion and infectivity of viral particles. Importantly, castanospermine prevented mortality in a mouse model of dengue virus infection, with doses of 10, 50, and 250 mg/kg of body weight per day being highly effective at promoting survival (P < or = 0.0001). Correspondingly, castanospermine had no adverse or protective effect on West Nile virus mortality in an analogous mouse model. Overall, our data suggest that castanospermine has a strong antiviral effect on dengue virus infection and warrants further development as a possible treatment in humans.
Collapse
Affiliation(s)
- Kevin Whitby
- Department of Medicine, Washington University School of Medicine, 660 South Euclid Avenue, Box 8051, St. Louis, MO 63110, USA
| | | | | | | | | | | | | | | |
Collapse
|
43
|
Zheng X, Feng CG, Ye JL, Huang PQ. Samarium Diiodide Promoted Generation and Asymmetric Hydroxyalkylation of N,O-Diprotected (3S)-3-Pyrrolidinol 2-Carbanions. Org Lett 2005; 7:553-6. [PMID: 15704892 DOI: 10.1021/ol047733z] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The N,O-diprotected chiral nonracemic 2-pyridyl 3-pyrrolidinol-2-yl sulfide 5a undergoes efficient SmI(2) mediated reduction to give the N,O-diprotected 3-pyrrolidinol 2-carbanion intermediate D, which reacted under Barbier-type conditions with ketones and aldehydes to afford the protected N-alpha-hydroxyalkyl-3-pyrrolidines 10b-h with excellent diastereoselectivity at the newly formed chiral center in the pyrrolidine ring. Application of the present method led to the formal asymmetric syntheses of (2R,3S)-2-hydroxymethyl-3-pyrrolidinol (2) and (2S,3S)-3-hydroxyproline (12). [reaction: see text]
Collapse
Affiliation(s)
- Xiao Zheng
- Department of Chemistry and The Key Laboratory for Chemical Biology of Fujian Province, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, P. R. China
| | | | | | | |
Collapse
|
44
|
Vathipadiekal V, Rao M. Inhibition of 1,4-beta-D-xylan xylanohydrolase by the specific aspartic protease inhibitor pepstatin: probing the two-step inhibition mechanism. J Biol Chem 2004; 279:47024-33. [PMID: 15317808 DOI: 10.1074/jbc.m407866200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
This is the first report that describes the inhibition mechanism of xylanase from Thermomonospora sp. by pepstatin A, a specific inhibitor toward aspartic proteases. The kinetic analysis revealed competitive inhibition of xylanase by pepstatin A with an IC50 value 3.6 +/- 0.5 microm. The progress curves were time-depended, consistent with a two-step slow tight binding inhibition. The inhibition followed a rapid equilibrium step to form a reversible enzyme-inhibitor complex (EI), which isomerizes to the second enzyme-inhibitor complex (EI*), which dissociated at a very slow rate. The rate constants determined for the isomerization of EI to EI* and the dissociation of EI* were 15 +/- 1 x 10(-5) and 3.0 +/- 1 x 10(-8) s(-1), respectively. The Ki value for the formation of EI complex was 1.5 +/- 0.5 microm, whereas the overall inhibition constant Ki* was 28.0 +/- 1 nm. The conformational changes induced in Xyl I by pepstatin A were monitored by fluorescence spectroscopy, and the rate constants derived were in agreement with the kinetic data. Thus, the conformational alterations were correlated to the isomerization of EI to EI*. Pepstatin A binds to the active site of the enzyme and disturbs the native interaction between the histidine and lysine, as demonstrated by the abolished isoindole fluorescence of o-phthalaldehyde-labeled xylanase. Our results revealed that the inactivation of xylanase is due to the interference in the electronic microenvironment and disruption of the hydrogen-bonding network between the essential histidine and other residues involved in catalysis, and a model depicting the probable interaction between pepstatin A with xylanase has been proposed.
Collapse
Affiliation(s)
- Vinod Vathipadiekal
- Division of Biochemical Sciences, National Chemical Laboratory, Pune 411-008, India
| | | |
Collapse
|
45
|
Winklhofer KF, Heller U, Reintjes A, Tatzelt J. Inhibition of complex glycosylation increases the formation of PrPsc. Traffic 2003; 4:313-22. [PMID: 12713659 DOI: 10.1034/j.1600-0854.2003.00088.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
N-linked glycans with complex structure have a major role in the biological activity of a wide variety of cell surface and secreted glycoproteins. Here, we show that geldanamycin, an inhibitor of Hsp90, interferes with the formation of complex glycosylated mammalian prion protein (PrPC). Similarly to inhibitors of alpha-mannosidases, geldanamycin stabilized a high mannose PrPC glycoform and prevented the subsequent processing into complex structures. Moreover, a PrP/Grp94 complex could be isolated from geldanamycin-treated cells, suggesting that Grp94 might play a role in the processing of PrPC in the endoplasmic reticulum. Inhibition of complex glycosylation did not interfere with the glycosylphosphatidylinositol (GPI) anchor attachment and cellular trafficking of high mannose PrPC to the outer leaflet of the plasma membrane. In scrapie-infected neuroblastoma cells, however, high mannose PrPC glycoforms were preferred substrates for the formation of PrP-scrapie (PrPSc). Our study reveals that complex glycosylation is dispensable for the cellular trafficking of PrPC, but modulates the formation of PrPSc.
Collapse
Affiliation(s)
- Konstanze F Winklhofer
- Department of Cellular Biochemistry, Max-Planck-Institute for Biochemistry, 82152 Martinsried, Germany
| | | | | | | |
Collapse
|
46
|
Winklhofer KF, Heske J, Heller U, Reintjes A, Muranyi W, Moarefi I, Tatzelt J. Determinants of the in vivo folding of the prion protein. A bipartite function of helix 1 in folding and aggregation. J Biol Chem 2003; 278:14961-70. [PMID: 12556465 DOI: 10.1074/jbc.m209942200] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Misfolding of the mammalian prion protein (PrP) is implicated in the pathogenesis of prion diseases. We analyzed wild type PrP in comparison with different PrP mutants and identified determinants of the in vivo folding pathway of PrP. The complete N terminus of PrP including the putative transmembrane domain and the first beta-strand could be deleted without interfering with PrP maturation. Helix 1, however, turned out to be a major determinant of PrP folding. Disruption of helix 1 prevented attachment of the glycosylphosphatidylinositol (GPI) anchor and the formation of complex N-linked glycans; instead, a high mannose PrP glycoform was secreted into the cell culture supernatant. In the absence of a C-terminal membrane anchor, however, helix 1 induced the formation of unglycosylated and partially protease-resistant PrP aggregates. Moreover, we could show that the C-terminal GPI anchor signal sequence, independent of its role in GPI anchor attachment, mediates core glycosylation of nascent PrP. Interestingly, conversion of high mannose glycans to complex type glycans only occurred when PrP was membrane-anchored. Our study indicates a bipartite function of helix 1 in the maturation and aggregation of PrP and emphasizes a critical role of a membrane anchor in the formation of complex glycosylated PrP.
Collapse
Affiliation(s)
- Konstanze F Winklhofer
- Department of Cellular Biochemistry, Max-Planck-Institut für Biochemie, Am Klopferspitz 18A, D-82152 Martinsried, Germany
| | | | | | | | | | | | | |
Collapse
|
47
|
Serkedjieva J, Velcheva M. In vitro anti-influenza virus activity of the pavine alkaloid (-)-thalimonine isolated from Thalictrum simplex L. Antivir Chem Chemother 2003; 14:75-80. [PMID: 12856918 DOI: 10.1177/095632020301400202] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The pavine alkaloid (-)-thalimonine (Thl), isolated from the Mongolian plant Thalictrum simplex inhibited markedly the reproduction of influenza virus A/Germany/27, str. Weybridge (H7N7) and A/Germany/34, str. Rostock (H7N1) in cell cultures of chicken embryo fibroblasts. In a number of assays at a non-toxic concentration range of 0.1-6.4 microM the alkaloid inhibited viral reproduction in a selective and specific way (selectivity index = 640, 106.6, respectively). Expression of viral glycoproteins haemagglutinin (HA), neuraminidase (NA) and nucleoprotein (NP) on the surface of infected cells, virus-induced cytopathic effect, infectious virus yields, HA production and virus-specific protein synthesis were all reduced. The inhibition was dose-related and depended on virus inoculum. The time of addition experiments indicated that viral reproduction was markedly inhibited when Thl was added at 4-5 h of infection. No inactivating effect on extracellular virus was found.
Collapse
Affiliation(s)
- Julia Serkedjieva
- Institute of Microbiology, Centre of Phytochemistry, Bulgarian Academy of Sciences, Sofia, Bulgaria.
| | | |
Collapse
|
48
|
|
49
|
Takahashi H. [Synthetic studies on sugar-related bioactive substances based on the ring transformation]. YAKUGAKU ZASSHI 2002; 122:755-71. [PMID: 12400157 DOI: 10.1248/yakushi.122.755] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The development of two novel ring conversions of sugar derivatives is described. The first is an efficient conversion of 5-enopyranosides and 6-O-acetyl-5-enopyranosides to the corresponding substituted cyclohexanones mediated by a catalytic amount of palladium dichloride. After a survey of various substrates, the reaction was confirmed to be general and useful. Syntheses of bioactive compounds utilizing this method were therefore investigated. Cyclophellitol, which is a potent beta-glucoidase inhibitor, and its diastereoisomer were efficiently synthesized. Furthermore, novel synthesis of all enantiomerically pure diastereoisomers of inositol starting with 6-O-acetyl-5-enopyranosides was investigated. Good accessibility of these enantiomerically pure inositol diastereoisomers results in the efficient syntheses of D-myo-inositol 1,4,5-trisphosphate and D-myo-inositol 1,3,4,5-tetrakisphosphate. The second investigation involved novel and efficient conversion of D-glycono-1,5-lactones into the corresponding L-sugars. The important intermediate, delta-hydroxyalkoxamate, was provided by a practical alkoxyamination of D-glycono-1,5-lactones mediated by Me3Al. In contrast to the preparation of beta-lactam skeletons from beta-hydroxyalkoxamates, the cyclization of delta-hydroxyalkoxamates under Mitsunobu conditions resulted in O-alkylation rather than N-alkylation. It is noteworthy that delta-hydroxyalkoxamates derived from D-mannono-1,5-lactones afforded the O-alkylation product in 91% yield. No N-alkylation product was detected in this case. These O-cyclized oximes, in which the inversion of the configuration at C5 was secured, were efficiently converted into L-sugars.
Collapse
Affiliation(s)
- Hideyo Takahashi
- Faculty of Pharmaceutical Sciences, Teikyo University, Sagamiko, Kanagawa 199-0195.
| |
Collapse
|
50
|
White JD, Hrnciar P. Synthesis of polyhydroxylated pyrrolizidine alkaloids of the alexine family by tandem ring-closing metathesis-transannular cyclization. (+)-Australine. J Org Chem 2000; 65:9129-42. [PMID: 11149861 DOI: 10.1021/jo0012748] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Dienes 23 and 54, prepared from epoxy alcohol 9 via oxazolidinones 15 and 51, respectively, underwent ring-closing metathesis with Grubbs's catalyst to give azacyclooctenes 26 and 55. Treatment of each azacyclooctene with m-chloroperoxybenzoic acid afforded beta-epoxide 28 from 26 and alpha-epoxide 61 from 60. Basic hydrolysis of each of these oxazolidinones was accompanied by transannular attack at the epoxide by nitrogen, resulting in 2-(O-benzyl)-7-deoxyalexine (29) and 1,2-di-(O-benzyl)australine (62). The latter was converted to the alkaloid australine (3) upon hydrogenolysis. Attempts to effect ring-closing metathesis of dienes 37, 38, and 46 were unsuccessful, suggesting that, while one allylic oxygen substituent can be tolerated by Grubbs's catalyst, two cannot.
Collapse
Affiliation(s)
- J D White
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331-4003, USA.
| | | |
Collapse
|