1
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Garber JM, Fordwour OB, Zandberg WF. A Rapid Protocol for Preparing 8-Aminopyrene-1,3,6-Trisulfonate-Labeled Glycans for Capillary Electrophoresis-Based Enzyme Assays. Methods Mol Biol 2023; 2657:223-239. [PMID: 37149535 DOI: 10.1007/978-1-0716-3151-5_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Purified glycan standards are required for glycan arrays, characterizing substrate specificities of glycan-active enzymes, and to serve as retention-time or mobility standards for various separation techniques. This chapter describes a method for the rapid separation, and subsequent desalting, of glycans labeled with the highly fluorescent fluorophore 8-aminopyrene-1,3,6-trisulfonate (APTS). By using fluorophore-assisted carbohydrate electrophoresis (FACE) on polyacrylamide gels, a technique amenable to equipment readily available in most molecular biology laboratories, many APTS-labeled glycans can be simultaneously resolved. Excising specific gel bands containing the desired APTS-labeled glycans, followed by glycan elution from the gel by simple diffusion and subsequent solid-phase extraction (SPE)-based desalting, affords a single glycan species free of excess labeling reagents and buffer components. The described protocol also offers a simple, rapid method for the simultaneous removal of excess APTS and unlabeled glycan material from reaction mixtures. This chapter describes a FACE/SPE procedure ideal for preparing glycans for capillary electrophoresis (CE)-based enzyme assays, as well as for the purification of rare, commercially unavailable glycans from tissue culture samples.
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Affiliation(s)
- Jolene M Garber
- Department of Chemistry, The University of British Columbia, Kelowna, BC, Canada
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, AB, Canada
| | - Osei B Fordwour
- Department of Chemistry, The University of British Columbia, Kelowna, BC, Canada
| | - Wesley F Zandberg
- Department of Chemistry, The University of British Columbia, Kelowna, BC, Canada.
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2
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Klaver EJ, Dukes-Rimsky L, Kumar B, Xia ZJ, Dang T, Lehrman MA, Angel P, Drake RR, Freeze HH, Steet R, Flanagan-Steet H. Protease-dependent defects in N-cadherin processing drive PMM2-CDG pathogenesis. JCI Insight 2021; 6:153474. [PMID: 34784297 PMCID: PMC8783681 DOI: 10.1172/jci.insight.153474] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 11/10/2021] [Indexed: 11/17/2022] Open
Abstract
The genetic bases for the congenital disorders of glycosylation (CDG) continue to expand, but how glycosylation defects cause patient phenotypes remains largely unknown. Here, we combined developmental phenotyping and biochemical studies in a potentially new zebrafish model (pmm2sa10150) of PMM2-CDG to uncover a protease-mediated pathogenic mechanism relevant to craniofacial and motility phenotypes in mutant embryos. Mutant embryos had reduced phosphomannomutase activity and modest decreases in N-glycan occupancy as detected by matrix-assisted laser desorption ionization mass spectrometry imaging. Cellular analyses of cartilage defects in pmm2sa10150 embryos revealed a block in chondrogenesis that was associated with defective proteolytic processing, but seemingly normal N-glycosylation, of the cell adhesion molecule N-cadherin. The activities of the proconvertases and matrix metalloproteinases responsible for N-cadherin maturation were significantly altered in pmm2sa10150 mutant embryos. Importantly, pharmacologic and genetic manipulation of proconvertase activity restored matrix metalloproteinase activity, N-cadherin processing, and cartilage pathology in pmm2sa10150 embryos. Collectively, these studies demonstrate in CDG that targeted alterations in protease activity create a pathogenic cascade that affects the maturation of cell adhesion proteins critical for tissue development.
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Affiliation(s)
- Elsenoor J Klaver
- Complex Carbohydrate Research Center, University of Georgia, Athens, United States of America
| | - Lynn Dukes-Rimsky
- Research Department, Greenwood Genetic Center, Greenwood, United States of America
| | - Brijesh Kumar
- Research Department, Greenwood Genetic Center, Greenwood, United States of America
| | - Zhi-Jie Xia
- Human Genetics Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, United States of America
| | - Tammie Dang
- Department of Pharmacology, UT Southwestern Medical Center, Dallas, United States of America
| | - Mark A Lehrman
- Department of Pharmacology, UT Southwestern Medical Center, Dallas, United States of America
| | - Peggi Angel
- Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, United States of America
| | - Richard R Drake
- Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, United States of America
| | - Hudson H Freeze
- Human Genetics Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, United States of America
| | - Richard Steet
- Research Department, Greenwood Genetic Center, Greenwood, United States of America
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3
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Lu H, Lehrman MA, Pfeiffer JK. Use of a Glycan Library Reveals a New Model for Enteric Virus Oligosaccharide Binding and Virion Stabilization. J Virol 2020; 94:e01894-19. [PMID: 31852778 PMCID: PMC7158723 DOI: 10.1128/jvi.01894-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 12/09/2019] [Indexed: 02/08/2023] Open
Abstract
Enteric viruses infect the gastrointestinal tract, and bacteria can promote replication and transmission of several enteric viruses. Viruses can be inactivated by exposure to heat or bleach, but poliovirus, coxsackievirus B3, and reovirus can be stabilized by bacteria or bacterial polysaccharides, limiting inactivation and aiding transmission. We previously demonstrated that certain N-acetylglucosamine (GlcNAc)-containing polysaccharides can stabilize poliovirus. However, the detailed virus-glycan binding specificity and glycan chain length requirements, and thus the mechanism of virion stabilization, have been unclear. A previous limitation was our lack of defined-length glycans to probe mechanisms and consequences of virus-glycan interactions. Here, we generated a panel of polysaccharides and oligosaccharides to determine the properties required for binding and stabilization of poliovirus. Poliovirus virions are nonenveloped icosahedral 30-nm particles with 60 copies of each of four capsid proteins, VP1 to VP4. VP1 surrounds the 5-fold axis, and our past work indicates that this region likely contains the glycan binding site. We found that relatively short GlcNAc oligosaccharides, such as a six-unit GlcNAc oligomer, can bind poliovirus but fail to enhance virion stability. Virion stabilization required binding of long GlcNAc polymers of greater than 20 units. Our data suggest a model where GlcNAc polymers of greater than 20 units bind and bridge adjacent 5-fold axes, thus aiding capsid rigidity and stability. This study provides a deeper understanding of enteric virus-bacterial glycan interactions, which are important for virion environmental stability and transmission.IMPORTANCE Enteric viruses are transmitted through the fecal-oral route, but how enteric viruses survive in the environment is unclear. Previously, we found that bacterial polysaccharides enhance poliovirus stability against heat or bleach inactivation, but the specific molecular requirements have been unknown. Here, we showed that certain short-chain oligosaccharides can bind to poliovirus but do not increase virion stability. Long-chain polysaccharides bind and may bridge adjacent sites on the viral surface, thus increasing capsid rigidity and stability. This work defines the unique interactions of poliovirus and glycans, which provides insight into virion environmental stability and transmission.
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Affiliation(s)
- Hua Lu
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Mark A Lehrman
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Julie K Pfeiffer
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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4
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Lu H, Cherepanova NA, Gilmore R, Contessa JN, Lehrman MA. Targeting STT3A-oligosaccharyltransferase with NGI-1 causes herpes simplex virus 1 dysfunction. FASEB J 2019; 33:6801-6812. [PMID: 30811219 DOI: 10.1096/fj.201802044rr] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Herpes simplex virus 1 (HSV-1) is a contagious neurotropic herpesvirus responsible for oral lesions and herpesviral encephalitis. The HSV-1 envelope contains N-glycosylated proteins involved in infection and that are candidate drug targets. NGI-1 is a small-molecule inhibitor of oligosaccharyltransferase (OST) complexes STT3A-OST and STT3B-OST, which catalyze cotranslational and post-translational N-glycosylation, respectively. Because host OSTs attach HSV-1 glycans, NGI-1 might have anti-HSV-1 activity. We evaluated HSV-1 function using NGI-1 and human embryonic kidney 293 knockout lines for OST isoform-specific catalytic and accessory subunits. N-glycosylation of 2 representative envelope proteins (gC and gD) was primarily dependent upon STT3A-OST, but to a large extent replaceable by STT3B-OST. Knockouts impairing STT3A- or STT3B-OST activity, by themselves, did not appreciably affect HSV-1 function (plaque-forming units, normalized to viral particles measured by unglycosylated capsid protein VP5 content). However, with cells lacking STT3B-OST activity (missing the catalytic subunit STT3B or the oxidoreductase subunits magnesium transporter 1/tumor suppressor candidate 3) and thus solely dependent upon STT3A-OST for N-glycosylation, NGI-1 treatment resulted in HSV-1 having cell type-dependent dysfunction (affecting infectivity with Vero cells much more than with the 293 lines). Ablation of post-translational N-glycosylation can therefore make HSV-1 infectivity, and possibly masking of immunogenic peptide epitopes by glycans, highly sensitive to pharmacological inhibition of cotranslational N-glycosylation.-Lu, H., Cherepanova, N. A., Gilmore, R., Contessa, J. N., Lehrman, M. A. Targeting STT3A-oligosaccharyltransferase with NGI-1 causes herpes simplex virus 1 dysfunction.
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Affiliation(s)
- Hua Lu
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Natalia A Cherepanova
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Reid Gilmore
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Joseph N Contessa
- Department of Therapeutic Radiology and Pharmacology, Yale School of Medicine, New Haven, Connecticut, USA.,Department of Pharmacology, Yale School of Medicine, New Haven, Connecticut, USA
| | - Mark A Lehrman
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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5
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Lu H, Sathe AA, Xing C, Lehrman MA. The Lec5 glycosylation mutant links homeobox genes with cholesterol and lipid-linked oligosaccharides. Glycobiology 2019; 29:106-109. [PMID: 30388226 PMCID: PMC6330018 DOI: 10.1093/glycob/cwy103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 11/01/2018] [Indexed: 11/12/2022] Open
Abstract
Discovered 40 years ago, the Lec5 glycosylation mutant cell line has a complex recessive genotype and is characterized by accumulation of lipid-linked oligosaccharide assembly intermediates, reduced conversion of polyprenols to dolichols, and an unusual phenotypic dependence upon cell culture conditions such as temperature, plating density and medium quality. The heritable defect in Lec5 is unknown. Here we demonstrate an unexpected epigenetic basis for Lec5, with a surprising linkage to increased expression of homeobox genes, which in turn is associated with increased transcription of cholesterol biosynthesis genes. These results suggest testable hypotheses for the biochemical abnormalities of the Lec5 mutant.
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Affiliation(s)
- Hua Lu
- Department of Pharmacology, UT Southwestern Medical Center, 6001 Forest Park Rd., Dallas, TX, USA
| | - Adwait Amod Sathe
- Eugene McDermott Center for Human Growth & Development, UT Southwestern Medical Center, 6001 Forest Park Rd., Dallas, TX, USA
| | - Chao Xing
- Eugene McDermott Center for Human Growth & Development, UT Southwestern Medical Center, 6001 Forest Park Rd., Dallas, TX, USA
- Department of Bioinformatics, UT Southwestern Medical Center, 6001 Forest Park Rd., Dallas, TX, USA
- Department of Clinical Sciences, UT Southwestern Medical Center, 6001 Forest Park Rd., Dallas, TX, USA
| | - Mark A Lehrman
- Department of Pharmacology, UT Southwestern Medical Center, 6001 Forest Park Rd., Dallas, TX, USA
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Obregón A, Flores MS, Rangel R, Arévalo K, Maldonado G, Quintero I, Galán L. Characterization of N-glycosylations in Entamoeba histolytica ubiquitin. Exp Parasitol 2019; 196:38-47. [DOI: 10.1016/j.exppara.2018.11.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Revised: 11/10/2018] [Accepted: 11/13/2018] [Indexed: 12/30/2022]
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7
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Mammalian STT3A/B oligosaccharyltransferases segregate N-glycosylation at the translocon from lipid-linked oligosaccharide hydrolysis. Proc Natl Acad Sci U S A 2018; 115:9557-9562. [PMID: 30181269 DOI: 10.1073/pnas.1806034115] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Oligosaccharyltransferases (OSTs) N-glycosylate proteins by transferring oligosaccharides from lipid-linked oligosaccharides (LLOs) to asparaginyl residues of Asn-Xaa-Ser/Thr acceptor sequons. Mammals have OST isoforms with STT3A or STT3B catalytic subunits for cotranslational or posttranslational N-glycosylation, respectively. OSTs also hydrolyze LLOs, forming free oligosaccharides (fOSs). It has been unclear whether hydrolysis is due to one or both OSTs, segregated from N-glycosylation, and/or regulated. Transfer and hydrolysis were assayed in permeabilized HEK293 kidney and Huh7.5.1 liver cells lacking STT3A or STT3B. Transfer by both STT3A-OST and STT3B-OST with synthetic acceptors was robust. LLO hydrolysis by STT3B-OST was readily detected and surprisingly modulated: Without acceptors, STT3B-OST hydrolyzed Glc3Man9GlcNAc2-LLO but not Man9GlcNAc2-LLO, yet it hydrolyzed both LLOs with acceptors present. In contrast, LLO hydrolysis by STT3A-OST was negligible. STT3A-OST however may be regulatory, because it suppressed STT3B-OST-dependent fOSs. TREX1, a negative innate immunity factor that diminishes immunogenic fOSs derived from LLOs, acted through STT3B-OST as well. In summary, only STT3B-OST hydrolyzes LLOs, depending upon LLO quality and acceptor site occupancy. TREX1 and STT3A suppress STT3B-OST-dependent fOSs. Without strict kinetic limitations during posttranslational N-glycosylation, STT3B-OST can thus moonlight for LLO hydrolysis. In contrast, the STT3A-OST/translocon complex preserves LLOs for temporally fastidious cotranslational N-glycosylation.
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8
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Glasscock CJ, Yates LE, Jaroentomeechai T, Wilson JD, Merritt JH, Lucks JB, DeLisa MP. A flow cytometric approach to engineering Escherichia coli for improved eukaryotic protein glycosylation. Metab Eng 2018; 47:488-495. [DOI: 10.1016/j.ymben.2018.04.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 04/17/2018] [Accepted: 04/19/2018] [Indexed: 12/31/2022]
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9
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Hamilton BS, Wilson JD, Shumakovich MA, Fisher AC, Brooks JC, Pontes A, Naran R, Heiss C, Gao C, Kardish R, Heimburg-Molinaro J, Azadi P, Cummings RD, Merritt JH, DeLisa MP. A library of chemically defined human N-glycans synthesized from microbial oligosaccharide precursors. Sci Rep 2017; 7:15907. [PMID: 29162910 PMCID: PMC5698433 DOI: 10.1038/s41598-017-15891-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 11/01/2017] [Indexed: 12/12/2022] Open
Abstract
Synthesis of homogenous glycans in quantitative yields represents a major bottleneck to the production of molecular tools for glycoscience, such as glycan microarrays, affinity resins, and reference standards. Here, we describe a combined biological/enzymatic synthesis that is capable of efficiently converting microbially-derived precursor oligosaccharides into structurally uniform human-type N-glycans. Unlike starting material obtained by chemical synthesis or direct isolation from natural sources, which can be time consuming and costly to generate, our approach involves precursors derived from renewable sources including wild-type Saccharomyces cerevisiae glycoproteins and lipid-linked oligosaccharides from glycoengineered Escherichia coli. Following deglycosylation of these biosynthetic precursors, the resulting microbial oligosaccharides are subjected to a greatly simplified purification scheme followed by structural remodeling using commercially available and recombinantly produced glycosyltransferases including key N-acetylglucosaminyltransferases (e.g., GnTI, GnTII, and GnTIV) involved in early remodeling of glycans in the mammalian glycosylation pathway. Using this approach, preparative quantities of hybrid and complex-type N-glycans including asymmetric multi-antennary structures were generated and subsequently used to develop a glycan microarray for high-throughput, fluorescence-based screening of glycan-binding proteins. Taken together, these results confirm our combined synthesis strategy as a new, user-friendly route for supplying chemically defined human glycans simply by combining biosynthetically-derived precursors with enzymatic remodeling.
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Affiliation(s)
- Brian S Hamilton
- Glycobia, Inc., 33 Thornwood Drive, Suite 104, Ithaca, New York, 14850, USA
| | - Joshua D Wilson
- Glycobia, Inc., 33 Thornwood Drive, Suite 104, Ithaca, New York, 14850, USA
| | | | - Adam C Fisher
- Glycobia, Inc., 33 Thornwood Drive, Suite 104, Ithaca, New York, 14850, USA
| | - James C Brooks
- Glycobia, Inc., 33 Thornwood Drive, Suite 104, Ithaca, New York, 14850, USA
| | - Alyssa Pontes
- Glycobia, Inc., 33 Thornwood Drive, Suite 104, Ithaca, New York, 14850, USA
| | - Radnaa Naran
- Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Road, Athens, GA, 30602, USA
| | - Christian Heiss
- Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Road, Athens, GA, 30602, USA
| | - Chao Gao
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Robert Kardish
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Jamie Heimburg-Molinaro
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Parastoo Azadi
- Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Road, Athens, GA, 30602, USA
| | - Richard D Cummings
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Judith H Merritt
- Glycobia, Inc., 33 Thornwood Drive, Suite 104, Ithaca, New York, 14850, USA
| | - Matthew P DeLisa
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York, 14853, USA.
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10
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Beriault DR, Dang VT, Zhong LH, Petlura CI, McAlpine CS, Shi Y, Werstuck GH. Glucosamine induces ER stress by disrupting lipid-linked oligosaccharide biosynthesis and N-linked protein glycosylation. Am J Physiol Endocrinol Metab 2017; 312:E48-E57. [PMID: 27879249 DOI: 10.1152/ajpendo.00275.2016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 10/28/2016] [Accepted: 11/15/2016] [Indexed: 11/22/2022]
Abstract
Glucosamine is an essential substrate for N-linked protein glycosylation. However, elevated levels of glucosamine can induce endoplasmic reticulum (ER) stress. Glucosamine-induced ER stress has been implicated in the development of diabetic complications, including atherosclerosis and hepatic steatosis. In this study, we investigate the potential relationship between the effects of glucosamine on lipid-linked oligosaccharide (LLO) biosynthesis, N-linked glycosylation, and ER homeostasis. Mouse embryonic fibroblasts (MEFs) were cultured in the presence of 0-5 mM glucosamine for up to 18 h, and LLO biosynthesis was monitored by fluorescence-assisted carbohydrate electrophoresis. ER stress was determined by quantification of unfolded protein response (UPR) gene expression. We found that exposure of MEFs to ≥1 mM glucosamine significantly impaired the biosynthesis of mature (Glc3Man9GlcNAc2) LLOs before the activation of the UPR, which resulted in the accumulation of an LLO intermediate (Man3GlcNAc2). The addition of 4-phenylbutyric acid (4-PBA), a chemical chaperone, was able to alleviate ER stress but did not rescue LLO biosynthesis. Other ER stress-inducing agents, including dithiothreitol and thapsigargin, had no effect on LLO levels. Together, these data suggest that elevated concentrations of glucosamine induce ER stress by interfering with lipid-linked oligosaccharide biosynthesis and N-linked glycosylation. We hypothesize that this pathway represents a causative link between hyperglycemia and the development of diabetic complications.
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Affiliation(s)
- Daniel R Beriault
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
- Thrombosis and Atherosclerosis Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Vi T Dang
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario, Canada
- Thrombosis and Atherosclerosis Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Lexy H Zhong
- Thrombosis and Atherosclerosis Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Christina I Petlura
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario, Canada
- Thrombosis and Atherosclerosis Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Cameron S McAlpine
- Department of Medicine McMaster University, Hamilton, Ontario, Canada; and
- Thrombosis and Atherosclerosis Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Yuanyuan Shi
- Thrombosis and Atherosclerosis Research Institute, McMaster University, Hamilton, Ontario, Canada
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11
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Danyluk HJ, Shum LK, Zandberg WF. A Rapid Procedure for the Purification of 8-Aminopyrene Trisulfonate (APTS)-Labeled Glycans for Capillary Electrophoresis (CE)-Based Enzyme Assays. Methods Mol Biol 2017; 1588:223-236. [PMID: 28417373 DOI: 10.1007/978-1-4939-6899-2_18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Purified glycan standards are required for glycan arrays, characterizing substrate specificities of glycan-active enzymes, and to serve as retention-time or mobility standards for various separation techniques. This chapter describes a method for the rapid separation, and subsequent desalting, of glycans labeled with the highly fluorescent fluorophore 8-aminopyrene 1,3,6-trisulfonate (APTS). By using fluorophore-assisted carbohydrate electrophoresis (FACE) on polyacrylamide gels, which utilizes equipment readily available in most molecular biology laboratories, many APTS-labeled glycans can be simultaneously resolved. Excising specific gel bands containing the desired APTS-labeled glycans, followed by glycan elution from the gel and subsequent solid-phase extraction (SPE), yields single glycan species free of excess labeling reagents and buffer components. This chapter describes a FACE/SPE procedure ideal for preparing glycans for capillary electrophoresis (CE)-based enzyme assays, as well as for the purification of rare, commercially unavailable glycans from tissue culture samples.
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Affiliation(s)
- Hayden J Danyluk
- Simon Fraser University, Department of Molecular Biology and Biochemistry, 8888 University Drive, Burnaby, BC, Canada, V5A 1S6
| | - Leona K Shum
- Department of Chemistry, The University of British Columbia, Okanagan, Kelowna, BC, Canada
| | - Wesley F Zandberg
- Department of Chemistry, The University of British Columbia, Okanagan, Kelowna, BC, Canada.
- Department of Chemistry, Science Building, 1177 Research Road, Kelowna, BC, Canada, V1M 1V7.
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12
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Hasan M, Fermaintt CS, Gao N, Sakai T, Miyazaki T, Jiang S, Li QZ, Atkinson JP, Morse HC, Lehrman MA, Yan N. Cytosolic Nuclease TREX1 Regulates Oligosaccharyltransferase Activity Independent of Nuclease Activity to Suppress Immune Activation. Immunity 2015; 43:463-74. [PMID: 26320659 DOI: 10.1016/j.immuni.2015.07.022] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 06/04/2015] [Accepted: 06/19/2015] [Indexed: 01/01/2023]
Abstract
TREX1 is an endoplasmic reticulum (ER)-associated negative regulator of innate immunity. TREX1 mutations are associated with autoimmune and autoinflammatory diseases. Biallelic mutations abrogating DNase activity cause autoimmunity by allowing immunogenic self-DNA to accumulate, but it is unknown how dominant frameshift (fs) mutations that encode DNase-active but mislocalized proteins cause disease. We found that the TREX1 C terminus suppressed immune activation by interacting with the ER oligosaccharyltransferase (OST) complex and stabilizing its catalytic integrity. C-terminal truncation of TREX1 by fs mutations dysregulated the OST complex, leading to free glycan release from dolichol carriers, as well as immune activation and autoantibody production. A connection between OST dysregulation and immune disorders was demonstrated in Trex1(-/-) mice, TREX1-V235fs patient lymphoblasts, and TREX1-V235fs knock-in mice. Inhibiting OST with aclacinomycin corrects the glycan and immune defects associated with Trex1 deficiency or fs mutation. This function of the TREX1 C terminus suggests a potential therapeutic option for TREX1-fs mutant-associated diseases.
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Affiliation(s)
- Maroof Hasan
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Charles S Fermaintt
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Ningguo Gao
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Tomomi Sakai
- Virology and Cellular Immunology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, NIH, Rockville, MD 20852, USA
| | - Takuya Miyazaki
- Virology and Cellular Immunology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, NIH, Rockville, MD 20852, USA
| | - Sixin Jiang
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Quan-Zhen Li
- Department of Immunology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - John P Atkinson
- Department of Medicine, Division of Rheumatology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Herbert C Morse
- Virology and Cellular Immunology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, NIH, Rockville, MD 20852, USA
| | - Mark A Lehrman
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Nan Yan
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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13
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Sharma V, Ichikawa M, Freeze HH. Mannose metabolism: more than meets the eye. Biochem Biophys Res Commun 2014; 453:220-8. [PMID: 24931670 PMCID: PMC4252654 DOI: 10.1016/j.bbrc.2014.06.021] [Citation(s) in RCA: 141] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 06/04/2014] [Indexed: 12/29/2022]
Abstract
Mannose is a simple sugar with a complex life. It is a welcome therapy for genetic and acquired human diseases, but it kills honeybees and blinds baby mice. It could cause diabetic complications. Mannose chemistry, metabolism, and metabolomics in cells, tissues and mammals can help explain these multiple systemic effects. Mannose has good, bad or ugly outcomes depending on its steady state levels and metabolic flux. This review describes the role of mannose at cellular level and its impact on organisms.
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Affiliation(s)
- Vandana Sharma
- Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA.
| | - Mie Ichikawa
- Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
| | - Hudson H Freeze
- Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
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14
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Srichaisupakit A, Ohashi T, Misaki R, Fujiyama K. Production of initial-stage eukaryotic N-glycan and its protein glycosylation in Escherichia coli. J Biosci Bioeng 2014; 119:399-405. [PMID: 25449758 DOI: 10.1016/j.jbiosc.2014.09.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Revised: 09/13/2014] [Accepted: 09/17/2014] [Indexed: 11/20/2022]
Abstract
N-Glycosylation is a ubiquitous protein post-translational modification mechanism in eukaryotes. In this work, a synthetic pathway containing glycosyltransferases from Saccharomyces cerevisiae was introduced to Escherichia coli to synthesize lipid-linked mannosyl-chitobiose (Man-GlcNAc2) and trimannosyl-chitobiose (Man3-GlcNAc2). Transfer of Man3-GlcNAc2 onto a model periplasmic protein occurred in the engineered E. coli cell using oligosaccharyltransferase PglB from Campylobacter jejuni. Mass spectrometric analysis of the fluorescently labeled N-glycan indicated a glycan signal composed of 2 HexNAc and 3 Hex residues. The reversed-phase HPLC analysis suggested that the Hex residues were α1,3-, α1,6- and β1,4-linked mannoses. These results indicated that the constructed system synthesizes a Man3-GlcNAc2, identical to that observed in an early eukaryotic dolichol pathway. Finally, glycopeptide mass spectrometry confirmed the transfer of the assembled glycan moiety onto an engineered glycosylation motif of recombinant maltose binding protein. Surprisingly, the Man3-GlcNAc2 structure but not Man-GlcNAc2 was transferred onto maltose binding protein. This work showed that PglB protein might be able to accommodate the transfer of the further engineered glycan with greater complexity.
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Affiliation(s)
| | - Takao Ohashi
- International Center for Biotechnology, Osaka University, Suita, Osaka 565-0871, Japan
| | - Ryo Misaki
- International Center for Biotechnology, Osaka University, Suita, Osaka 565-0871, Japan
| | - Kazuhito Fujiyama
- International Center for Biotechnology, Osaka University, Suita, Osaka 565-0871, Japan.
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15
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Wang ZV, Deng Y, Gao N, Pedrozo Z, Li DL, Morales CR, Criollo A, Luo X, Tan W, Jiang N, Lehrman MA, Rothermel BA, Lee AH, Lavandero S, Mammen PPA, Ferdous A, Gillette TG, Scherer PE, Hill JA. Spliced X-box binding protein 1 couples the unfolded protein response to hexosamine biosynthetic pathway. Cell 2014; 156:1179-1192. [PMID: 24630721 DOI: 10.1016/j.cell.2014.01.014] [Citation(s) in RCA: 296] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Revised: 11/22/2013] [Accepted: 01/07/2014] [Indexed: 12/20/2022]
Abstract
The hexosamine biosynthetic pathway (HBP) generates uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) for glycan synthesis and O-linked GlcNAc (O-GlcNAc) protein modifications. Despite the established role of the HBP in metabolism and multiple diseases, regulation of the HBP remains largely undefined. Here, we show that spliced X-box binding protein 1 (Xbp1s), the most conserved signal transducer of the unfolded protein response (UPR), is a direct transcriptional activator of the HBP. We demonstrate that the UPR triggers HBP activation via Xbp1s-dependent transcription of genes coding for key, rate-limiting enzymes. We further establish that this previously unrecognized UPR-HBP axis is triggered in a variety of stress conditions. Finally, we demonstrate a physiologic role for the UPR-HBP axis by showing that acute stimulation of Xbp1s in heart by ischemia/reperfusion confers robust cardioprotection in part through induction of the HBP. Collectively, these studies reveal that Xbp1s couples the UPR to the HBP to protect cells under stress.
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Affiliation(s)
- Zhao V Wang
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Yingfeng Deng
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Ningguo Gao
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Zully Pedrozo
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Advanced Center for Chronic Diseases (ACCDiS) and Centro Estudios Moleculares de la Celula, Facultad Ciencias Quimicas y Farmaceuticas and Facultad Medicina, Universidad de Chile, Santiago, Chile; Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Dan L Li
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Cyndi R Morales
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Alfredo Criollo
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Advanced Center for Chronic Diseases (ACCDiS) and Centro Estudios Moleculares de la Celula, Facultad Ciencias Quimicas y Farmaceuticas and Facultad Medicina, Universidad de Chile, Santiago, Chile; Dental Science Research Institute, Facultad de Odontologia, Universidad de Chile, Santiago, Chile
| | - Xiang Luo
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Wei Tan
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Nan Jiang
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Mark A Lehrman
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Beverly A Rothermel
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Ann-Hwee Lee
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY 10065, USA
| | - Sergio Lavandero
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Advanced Center for Chronic Diseases (ACCDiS) and Centro Estudios Moleculares de la Celula, Facultad Ciencias Quimicas y Farmaceuticas and Facultad Medicina, Universidad de Chile, Santiago, Chile; Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Pradeep P A Mammen
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Anwarul Ferdous
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Thomas G Gillette
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Philipp E Scherer
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Joseph A Hill
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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16
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Gao N, Holmes J, Lehrman MA. Letter to the Glycoforum: Improved protocols for preparing lipid-linked and related saccharides for Fluorophore-Assisted Carbohydrate Electrophoresis (FACE). Glycobiology 2014; 23:1111. [PMID: 24014203 DOI: 10.1093/glycob/cwt067] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Ningguo Gao
- Department of Pharmacology, UT Southwestern Medical Center at Dallas, 6001 Forest Park Rd. Dallas, TX 75390-9041
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17
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Philips KB, Kurtoglu M, Leung HJ, Liu H, Gao N, Lehrman MA, Murray TG, Lampidis TJ. Increased sensitivity to glucose starvation correlates with downregulation of glycogen phosphorylase isoform PYGB in tumor cell lines resistant to 2-deoxy-D-glucose. Cancer Chemother Pharmacol 2014; 73:349-61. [PMID: 24292700 PMCID: PMC4570497 DOI: 10.1007/s00280-013-2358-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Accepted: 11/11/2013] [Indexed: 12/11/2022]
Abstract
BACKGROUND As tumors evolve, they upregulate glucose metabolism while also encountering intermittent periods of glucose deprivation. Here, we investigate mechanisms by which pancreatic cancer cells respond to therapeutic (2-deoxy-D-glucose, 2-DG) and physiologic (glucose starvation, GS) forms of glucose restriction. METHODS From a tumor cell line (1420) that is unusually sensitive to 2-DG under normoxia, low (14DG2)- and high (14DG5)-dose resistant cell lines were selected and used to probe the metabolic pathways involved with their response to different forms of glucose deprivation. RESULTS Muted induction of the unfolded protein response was found to correlate with resistance to 2-DG. Additionally, 14DG2 displayed reduced 2-DG uptake, while 14DG5 was cross-resistant to tunicamycin, suggesting it has enhanced ability to manage glycosylation defects. Conversely, 2-DG-resistant cell lines were more sensitive than their parental cell line to GS, which coincided with lowered levels of glycogen phosphorylase (PYGB) and reduced breakdown of glycogen to glucose in the 2-DG-resistant cell lines. Moreover, by inhibiting PYGB in the parental cell line, sensitivity to GS was increased. CONCLUSIONS Overall, the data demonstrate that the manner in which glucose is restricted in tumor cells, i.e., therapeutic or physiologic, leads to differential biological responses involving distinct glucose metabolic pathways. Moreover, in evolving tumors where glucose restriction occurs, the identification of PYGB as a metabolic target may have clinical application.
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Affiliation(s)
- Katherine B. Philips
- Sheila and David Fuente Graduate Program in Cancer Biology, University of Miami Miller School of Medicine, 1550 NW 10th Avenue, Fox Building #406, Miami, FL 33136, USA,
| | - Metin Kurtoglu
- Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, PAP Building, Room 115, 1550 NW 10th Ave, Miami, FL 33136, USA,
| | - Howard J. Leung
- Sheila and David Fuente Graduate Program in Cancer Biology, University of Miami Miller School of Medicine, 1550 NW 10th Avenue, Fox Building #406, Miami, FL 33136, USA,
| | - Huaping Liu
- Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, PAP Building, Room 115, 1550 NW 10th Ave, Miami, FL 33136, USA,
| | - Ningguo Gao
- Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park Rd., Dallas, TX 75390-9041, USA,
| | - Mark A. Lehrman
- Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park Rd., Dallas, TX 75390-9041, USA,
| | - Timothy G. Murray
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami, 900 NW 17th St., Miami, FL 33136, USA,
| | - Theodore J. Lampidis
- Department of Cell Biology (R-124), University of Miami Miller School of Medicine, 1600 NW 10th Avenue, Rosenstiel Medical Sciences Building #4026/4027, P.O. Box 016960, Miami, FL 33101, USA,
- Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, 1475 NW 12th Avenue, P.O. Box 016960, Miami, FL 33101, USA
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18
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Liu B, Villacres-Barragan C, Lattova E, Spearman M, Butler M. Differential affects of low glucose on the macroheterogeneity and microheterogeneity of glycosylation in CHO-EG2 camelid monoclonal antibodies. BMC Proc 2013. [PMCID: PMC3980241 DOI: 10.1186/1753-6561-7-s6-p112] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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19
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Liu B, Spearman M, Doering J, Lattová E, Perreault H, Butler M. The availability of glucose to CHO cells affects the intracellular lipid-linked oligosaccharide distribution, site occupancy and the N-glycosylation profile of a monoclonal antibody. J Biotechnol 2013; 170:17-27. [PMID: 24286971 DOI: 10.1016/j.jbiotec.2013.11.007] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 11/05/2013] [Accepted: 11/07/2013] [Indexed: 12/16/2022]
Abstract
The glycosylation pattern of a chimeric heavy chain antibody (EG2) produced from CHO cells was affected by the glucose concentration (0-25mM) of cultures established at high density (>10(6)ml(-1)) over 24h. The resulting proportion of non-glycosylated Mab was directly correlated to the exposure time of cells to media depleted of glucose. Deprivation of glucose for the full 24h resulted in a 45% non-glycosylated Mab fraction. Analysis of steady state levels of intracellular lipid-linked oligosaccharides (LLOs) showed that under glucose limitation there was a reduction in the amount of full length LLO (Glc3Man9GlcNac2), with a concomitant increase in the smaller mannosyl-glycans (Man2-5GlcNAc2). Glycan microheterogeneity was quantified by galactosylation and sialylation indices (GI and SI) which showed a direct correlation to the cell specific glucose uptake. The GI increased to 0.83 following media supplementation with a cocktail of uridine, manganese and galactose. This is significantly higher than for a fully humanized antibody (DP12) produced under the similar conditions or for similar antibodies reported in the literature. The high GI of the chimeric antibody (EG2) may be due to its low molecular weight and unusual structure. These findings are important in relation to the low substrate that may occur in fed-batch cultures for Mab production.
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Affiliation(s)
- Bo Liu
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2
| | - Maureen Spearman
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2
| | - John Doering
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2
| | - Erica Lattová
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2
| | - Hélène Perreault
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2
| | - Michael Butler
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2.
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20
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Jelk J, Gao N, Serricchio M, Signorell A, Schmidt RS, Bangs JD, Acosta-Serrano A, Lehrman MA, Bütikofer P, Menon AK. Glycoprotein biosynthesis in a eukaryote lacking the membrane protein Rft1. J Biol Chem 2013; 288:20616-23. [PMID: 23720757 PMCID: PMC3711325 DOI: 10.1074/jbc.m113.479642] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 05/21/2013] [Indexed: 12/13/2022] Open
Abstract
Mature dolichol-linked oligosaccharides (mDLOs) needed for eukaryotic protein N-glycosylation are synthesized by a multistep pathway in which the biosynthetic lipid intermediate Man5GlcNAc2-PP-dolichol (M5-DLO) flips from the cytoplasmic to the luminal face of the endoplasmic reticulum. The endoplasmic reticulum membrane protein Rft1 is intimately involved in mDLO biosynthesis. Yeast genetic analyses implicated Rft1 as the M5-DLO flippase, but because biochemical tests challenged this assignment, the function of Rft1 remains obscure. To understand the role of Rft1, we sought to analyze mDLO biosynthesis in vivo in the complete absence of the protein. Rft1 is essential for yeast viability, and no Rft1-null organisms are currently available. Here, we exploited Trypanosoma brucei (Tb), an early diverging eukaryote whose Rft1 homologue functions in yeast. We report that TbRft1-null procyclic trypanosomes grow nearly normally. They have normal steady-state levels of mDLO and significant N-glycosylation, indicating robust M5-DLO flippase activity. Remarkably, the mutant cells have 30-100-fold greater steady-state levels of M5-DLO than wild-type cells. All N-glycans in the TbRft1-null cells originate from mDLO indicating that the M5-DLO excess is not available for glycosylation. These results suggest that rather than facilitating M5-DLO flipping, Rft1 facilitates conversion of M5-DLO to mDLO by another mechanism, possibly by acting as an M5-DLO chaperone.
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Affiliation(s)
- Jennifer Jelk
- the Institute of Biochemistry and Molecular Medicine,
University of Bern, 3012 Bern, Switzerland
| | - Ningguo Gao
- the Department of Pharmacology, University of Texas
Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Mauro Serricchio
- the Institute of Biochemistry and Molecular Medicine,
University of Bern, 3012 Bern, Switzerland
| | - Aita Signorell
- From the Department of Biochemistry, Weill Cornell Medical
College, New York, New York 10065
| | - Remo S. Schmidt
- the Institute of Biochemistry and Molecular Medicine,
University of Bern, 3012 Bern, Switzerland
| | - James D. Bangs
- the Department of Microbiology and Immunology, School of
Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York 14214,
and
| | - Alvaro Acosta-Serrano
- the Parasitology and Vector Biology Departments,
Liverpool School of Tropical Medicine, Liverpool L3 5QA, United Kingdom
| | - Mark A. Lehrman
- the Department of Pharmacology, University of Texas
Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Peter Bütikofer
- the Institute of Biochemistry and Molecular Medicine,
University of Bern, 3012 Bern, Switzerland
| | - Anant K. Menon
- From the Department of Biochemistry, Weill Cornell Medical
College, New York, New York 10065
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21
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Xiang Y, Zhang X, Nix DB, Katoh T, Aoki K, Tiemeyer M, Wang Y. Regulation of protein glycosylation and sorting by the Golgi matrix proteins GRASP55/65. Nat Commun 2013; 4:1659. [PMID: 23552074 PMCID: PMC3620728 DOI: 10.1038/ncomms2669] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Accepted: 02/27/2013] [Indexed: 12/27/2022] Open
Abstract
The Golgi receives the entire output of newly synthesized cargo from the endoplasmic reticulum, processes it in the stack largely through modification of bound oligosaccharides, and sorts it in the trans-Golgi network. GRASP65 and GRASP55, two proteins localized to the Golgi stack and early secretory pathway, mediate processes including Golgi stacking, Golgi ribbon linking and unconventional secretion. Previously, we have shown that GRASP depletion in cells disrupts Golgi stack formation. Here we report that knockdown of the GRASP proteins, alone or combined, accelerates protein trafficking through the Golgi membranes but also has striking negative effects on protein glycosylation and sorting. These effects are not caused by Golgi ribbon unlinking, unconventional secretion or endoplasmic reticulum stress. We propose that GRASP55/65 are negative regulators of exocytic transport and that this slowdown helps to ensure more complete protein glycosylation in the Golgi stack and proper sorting at the trans-Golgi network.
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Affiliation(s)
- Yi Xiang
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, 830 North University Avenue, Ann Arbor, MI 48109-1048, USA
| | - Xiaoyan Zhang
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, 830 North University Avenue, Ann Arbor, MI 48109-1048, USA
| | - David B. Nix
- The Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602-4712, USA
- The Department of Biochemistry and Molecular Biology, B122 Life Sciences Building, University of Georgia, Athens, GA 30602-5016, USA
| | - Toshihiko Katoh
- The Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602-4712, USA
| | - Kazuhiro Aoki
- The Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602-4712, USA
| | - Michael Tiemeyer
- The Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602-4712, USA
- The Department of Biochemistry and Molecular Biology, B122 Life Sciences Building, University of Georgia, Athens, GA 30602-5016, USA
| | - Yanzhuang Wang
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, 830 North University Avenue, Ann Arbor, MI 48109-1048, USA
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22
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Deng Y, Wang ZV, Tao C, Gao N, Holland WL, Ferdous A, Repa JJ, Liang G, Ye J, Lehrman MA, Hill JA, Horton JD, Scherer PE. The Xbp1s/GalE axis links ER stress to postprandial hepatic metabolism. J Clin Invest 2012; 123:455-68. [PMID: 23257357 DOI: 10.1172/jci62819] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Accepted: 10/25/2012] [Indexed: 12/21/2022] Open
Abstract
Postprandially, the liver experiences an extensive metabolic reprogramming that is required for the switch from glucose production to glucose assimilation. Upon refeeding, the unfolded protein response (UPR) is rapidly, though only transiently, activated. Activation of the UPR results in a cessation of protein translation, increased chaperone expression, and increased ER-mediated protein degradation, but it is not clear how the UPR is involved in the postprandial switch to alternate fuel sources. Activation of the inositol-requiring enzyme 1 (IRE1) branch of the UPR signaling pathway triggers expression of the transcription factor Xbp1s. Using a mouse model with liver-specific inducible Xbp1s expression, we demonstrate that Xbp1s is sufficient to provoke a metabolic switch characteristic of the postprandial state, even in the absence of caloric influx. Mechanistically, we identified UDP-galactose-4-epimerase (GalE) as a direct transcriptional target of Xbp1s and as the key mediator of this effect. Our results provide evidence that the Xbp1s/GalE pathway functions as a novel regulatory nexus connecting the UPR to the characteristic postprandial metabolic changes in hepatocytes.
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Affiliation(s)
- Yingfeng Deng
- Touchstone Diabetes Center, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas 75390, USA
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23
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Cline A, Gao N, Flanagan-Steet H, Sharma V, Rosa S, Sonon R, Azadi P, Sadler KC, Freeze HH, Lehrman MA, Steet R. A zebrafish model of PMM2-CDG reveals altered neurogenesis and a substrate-accumulation mechanism for N-linked glycosylation deficiency. Mol Biol Cell 2012; 23:4175-87. [PMID: 22956764 PMCID: PMC3484097 DOI: 10.1091/mbc.e12-05-0411] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
PMM2-CDG patients have phosphomannomutase (Pmm2) deficiency, with developmental and N-linked glycosylation defects attributed to depletion of mannose-1-phosphate and downstream lipid-linked oligosaccharides (LLOs). This, the first PMM2-CDG zebrafish model, shows, unexpectedly, that accumulation of the Pmm2 substrate mannose-6-phosphate explains LLO deficiency. Congenital disorder of glycosylation (PMM2-CDG) results from mutations in pmm2, which encodes the phosphomannomutase (Pmm) that converts mannose-6-phosphate (M6P) to mannose-1-phosphate (M1P). Patients have wide-spectrum clinical abnormalities associated with impaired protein N-glycosylation. Although it has been widely proposed that Pmm2 deficiency depletes M1P, a precursor of GDP-mannose, and consequently suppresses lipid-linked oligosaccharide (LLO) levels needed for N-glycosylation, these deficiencies have not been demonstrated in patients or any animal model. Here we report a morpholino-based PMM2-CDG model in zebrafish. Morphant embryos had developmental abnormalities consistent with PMM2-CDG patients, including craniofacial defects and impaired motility associated with altered motor neurogenesis within the spinal cord. Significantly, global N-linked glycosylation and LLO levels were reduced in pmm2 morphants. Although M1P and GDP-mannose were below reliable detection/quantification limits, Pmm2 depletion unexpectedly caused accumulation of M6P, shown earlier to promote LLO cleavage in vitro. In pmm2 morphants, the free glycan by-products of LLO cleavage increased nearly twofold. Suppression of the M6P-synthesizing enzyme mannose phosphate isomerase within the pmm2 background normalized M6P levels and certain aspects of the craniofacial phenotype and abrogated pmm2-dependent LLO cleavage. In summary, we report the first zebrafish model of PMM2-CDG and uncover novel cellular insights not possible with other systems, including an M6P accumulation mechanism for underglycosylation.
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Affiliation(s)
- Abigail Cline
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
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24
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Chu J, Mir A, Gao N, Rosa S, Monson C, Sharma V, Steet R, Freeze HH, Lehrman MA, Sadler KC. A zebrafish model of congenital disorders of glycosylation with phosphomannose isomerase deficiency reveals an early opportunity for corrective mannose supplementation. Dis Model Mech 2012; 6:95-105. [PMID: 22899857 PMCID: PMC3529342 DOI: 10.1242/dmm.010116] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Individuals with congenital disorders of glycosylation (CDG) have recessive mutations in genes required for protein N-glycosylation, resulting in multi-systemic disease. Despite the well-characterized biochemical consequences in these individuals, the underlying cellular defects that contribute to CDG are not well understood. Synthesis of the lipid-linked oligosaccharide (LLO), which serves as the sugar donor for the N-glycosylation of secretory proteins, requires conversion of fructose-6-phosphate to mannose-6-phosphate via the phosphomannose isomerase (MPI) enzyme. Individuals who are deficient in MPI present with bleeding, diarrhea, edema, gastrointestinal bleeding and liver fibrosis. MPI-CDG patients can be treated with oral mannose supplements, which is converted to mannose-6-phosphate through a minor complementary metabolic pathway, restoring protein glycosylation and ameliorating most symptoms, although liver disease continues to progress. Because Mpi deletion in mice causes early embryonic lethality and thus is difficult to study, we used zebrafish to establish a model of MPI-CDG. We used a morpholino to block mpi mRNA translation and established a concentration that consistently yielded 13% residual Mpi enzyme activity at 4 days post-fertilization (dpf), which is within the range of MPI activity detected in fibroblasts from MPI-CDG patients. Fluorophore-assisted carbohydrate electrophoresis detected decreased LLO and N-glycans in mpi morphants. These deficiencies resulted in 50% embryonic lethality by 4 dpf. Multi-systemic abnormalities, including small eyes, dysmorphic jaws, pericardial edema, a small liver and curled tails, occurred in 82% of the surviving larvae. Importantly, these phenotypes could be rescued with mannose supplementation. Thus, parallel processes in fish and humans contribute to the phenotypes caused by Mpi depletion. Interestingly, mannose was only effective if provided prior to 24 hpf. These data provide insight into treatment efficacy and the broader molecular and developmental abnormalities that contribute to disorders associated with defective protein glycosylation.
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Affiliation(s)
- Jaime Chu
- Division of Pediatric Hepatology/Department of Pediatrics, Mount Sinai School of Medicine, New York, NY 10029, USA
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25
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Zandberg WF, Gao N, Kumarasamy J, Lehrman MA, Seidah NG, Pinto BM. 5-thiomannosides block the biosynthesis of dolichol-linked oligosaccharides and mimic class I congenital disorders of glycosylation. Chembiochem 2012; 13:392-401. [PMID: 22262650 PMCID: PMC3433809 DOI: 10.1002/cbic.201100647] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2011] [Indexed: 01/05/2023]
Abstract
In a cell-based assay for novel inhibitors, we have discovered that two glycosides of 5-thiomannose, each containing an interglycosidic nitrogen atom, prevented the correct zymogen processing of the prohormone proopiomelanocortinin (POMC) and the transcription factor sterol-regulatory element-binding protein-2 (SREBP-2) in mouse pituitary cells and Chinese hamster ovary (CHO) cells, respectively. In the case of SREBP-2, these effects were correlated with the altered N-linked glycosylation of subtilisin/kexin-like isozyme-1 (SKI-1), the protease responsible for SREBP-2 processing under sterol-limiting conditions. Further examination of the effects of these compounds in CHO cells showed that they cause extensive protein hypoglycosylation in a manner similar to type I congenital disorders of glycosylation (CDGs) since the remaining N-glycans in treated cells were complete (normal) structures. The under-glycosylation of glycoproteins in 5-thiomannoside-treated cells is now shown to be caused by the compromised biosynthesis of the dolichol-linked oligosaccharide (DLO) N-glycosylation donor, although the nucleotide sugars required for the synthesis of DLOs were neither reduced under these conditions, nor were their effects reversed upon the addition of exogenous mannose. Analysis of DLO intermediates by fluorophore-assisted carbohydrate electrophoresis demonstrated that 5-thiomannose-containing glycosides block DLO biosynthesis most likely at a stage prior to the GlcNAc(2) Man(3) intermediate, on the cytosolic face of the endoplasmic reticulum.
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Affiliation(s)
- Wesley F Zandberg
- Department of Chemistry, Simon Fraser University, Burnaby, BC, Canada, V5A 1S6
| | - Ningguo Gao
- Department of Pharmacology, UT-Southwestern Medical Center, Dallas, Texas, USA, 75390-9041
| | | | - Mark A Lehrman
- Department of Pharmacology, UT-Southwestern Medical Center, Dallas, Texas, USA, 75390-9041
| | - Nabil G Seidah
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, 110 Pine Avenue West Montreal, QC H2W 1R7, Canada
| | - B Mario Pinto
- Department of Chemistry, Simon Fraser University, Burnaby, BC, Canada, V5A 1S6
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26
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Gao N, Shang J, Huynh D, Manthati VL, Arias C, Harding HP, Kaufman RJ, Mohr I, Ron D, Falck JR, Lehrman MA. Mannose-6-phosphate regulates destruction of lipid-linked oligosaccharides. Mol Biol Cell 2011; 22:2994-3009. [PMID: 21737679 PMCID: PMC3164449 DOI: 10.1091/mbc.e11-04-0286] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Revised: 06/08/2011] [Accepted: 06/28/2011] [Indexed: 12/22/2022] Open
Abstract
Mannose-6-phosphate (M6P) is an essential precursor for mannosyl glycoconjugates, including lipid-linked oligosaccharides (LLO; glucose(3)mannose(9)GlcNAc(2)-P-P-dolichol) used for protein N-glycosylation. In permeabilized mammalian cells, M6P also causes specific LLO cleavage. However, the context and purpose of this paradoxical reaction are unknown. In this study, we used intact mouse embryonic fibroblasts to show that endoplasmic reticulum (ER) stress elevates M6P concentrations, leading to cleavage of the LLO pyrophosphate linkage with recovery of its lipid and lumenal glycan components. We demonstrate that this M6P originates from glycogen, with glycogenolysis activated by the kinase domain of the stress sensor IRE1-α. The apparent futility of M6P causing destruction of its LLO product was resolved by experiments with another stress sensor, PKR-like ER kinase (PERK), which attenuates translation. PERK's reduction of N-glycoprotein synthesis (which consumes LLOs) stabilized steady-state LLO levels despite continuous LLO destruction. However, infection with herpes simplex virus 1, an N-glycoprotein-bearing pathogen that impairs PERK signaling, not only caused LLO destruction but depleted LLO levels as well. In conclusion, the common metabolite M6P is also part of a novel mammalian stress-signaling pathway, responding to viral stress by depleting host LLOs required for N-glycosylation of virus-associated polypeptides. Apparently conserved throughout evolution, LLO destruction may be a response to a variety of environmental stresses.
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Affiliation(s)
- Ningguo Gao
- Departments of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390
| | - Jie Shang
- Departments of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390
| | - Dang Huynh
- Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390
| | - Vijaya L. Manthati
- Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390
| | - Carolina Arias
- Department of Microbiology, New York University School of Medicine, New York, NY 10016
| | - Heather P. Harding
- University of Cambridge Metabolic Research Laboratories, Cambridge CB2 0QQ, United Kingdom
| | - Randal J. Kaufman
- Departments of Internal Medicine and Biological Chemistry, University of Michigan Medical Center, Ann Arbor, MI 48109
| | - Ian Mohr
- Department of Microbiology, New York University School of Medicine, New York, NY 10016
| | - David Ron
- University of Cambridge Metabolic Research Laboratories, Cambridge CB2 0QQ, United Kingdom
| | - John R. Falck
- Departments of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390
- Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390
| | - Mark A. Lehrman
- Departments of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390
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27
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Harrison KD, Park EJ, Gao N, Kuo A, Rush JS, Waechter CJ, Lehrman MA, Sessa WC. Nogo-B receptor is necessary for cellular dolichol biosynthesis and protein N-glycosylation. EMBO J 2011; 30:2490-500. [PMID: 21572394 DOI: 10.1038/emboj.2011.147] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 04/13/2011] [Indexed: 11/09/2022] Open
Abstract
Dolichol monophosphate (Dol-P) functions as an obligate glycosyl carrier lipid in protein glycosylation reactions. Dol-P is synthesized by the successive condensation of isopentenyl diphosphate (IPP), with farnesyl diphosphate catalysed by a cis-isoprenyltransferase (cis-IPTase) activity. Despite the recognition of cis-IPTase activity 40 years ago and the molecular cloning of the human cDNA encoding the mammalian enzyme, the molecular machinery responsible for regulating this activity remains incompletely understood. Here, we identify Nogo-B receptor (NgBR) as an essential component of the Dol-P biosynthetic machinery. Loss of NgBR results in a robust deficit in cis-IPTase activity and Dol-P production, leading to diminished levels of dolichol-linked oligosaccharides and a broad reduction in protein N-glycosylation. NgBR interacts with the previously identified cis-IPTase hCIT, enhances hCIT protein stability, and promotes Dol-P production. Identification of NgBR as a component of the cis-IPTase machinery yields insights into the regulation of dolichol biosynthesis.
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Affiliation(s)
- Kenneth D Harrison
- Department of Pharmacology and Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT, USA
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28
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Abstract
When the homeostasis of endoplasmic reticulum (ER) is disturbed by the accumulation of unfolded or misfolded proteins, a series of signaling responses collectively called the unfolded protein response (UPR) is triggered. UPR transducers IRE1, PERK, ATF6, and UPR-responsive genes such as GRP78/BiP, ERAD genes such as EDEM, and synthesis of the protein N-linked glycosylation donor lipid-linked oligosaccharides (LLOs) are mobilized. This chapter provides methods used in our laboratory to quantitatively measure the accumulation of mRNAs encoding BiP and EDEM, splicing of XBP1, cleavage of ATF6, inhibition of protein synthesis by PERK, and extension of LLOs under control and stress conditions.
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Affiliation(s)
- Jie Shang
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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29
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Jones MB, Tomiya N, Betenbaugh MJ, Krag SS. Analysis and metabolic engineering of lipid-linked oligosaccharides in glycosylation-deficient CHO cells. Biochem Biophys Res Commun 2010; 395:36-41. [PMID: 20331963 DOI: 10.1016/j.bbrc.2010.03.117] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Accepted: 03/17/2010] [Indexed: 11/26/2022]
Abstract
Glycosylation-deficient Chinese Hamster Ovary (CHO) cell lines can be used to expand our understanding of N-glycosylation pathways and to study Congenital Disorders of Glycosylation, diseases caused by defects in the synthesis of N-glycans. The mammalian N-glycosylation pathway involves the step-wise assembly of sugars onto a dolichol phosphate (P-Dol) carrier, forming a lipid-linked oligosaccharide (LLO), followed by the transfer of the completed oligosaccharide onto the protein of interest. In order to better understand how deficiencies in this pathway affect the availability of the completed LLO donor for use in N-glycosylation, we used a non-radioactive, HPLC-based assay to examine the intermediates in the LLO synthesis pathway for CHO-K1 cells and for three different glycosylation-deficient CHO cell lines. B4-2-1 cells, which have a mutation in the dolichol phosphate-mannose synthase (DPM2) gene, accumulated LLO with the structure Man(5)GlcNAc(2)-P-P-Dol, while MI8-5 cells, which lack glucosyltransferase I (ALG6) activity, accumulated Man(9)GlcNAc(2)-P-P-Dol. CHO-K1 and MI5-4 cells both produced primarily the complete LLO, Glc(3)Man(9)GlcNAc(2)-P-P-Dol, though the relative quantity was lower in MI5-4. MI5-4 cells have reduced hexokinase activity which could affect the availability of many of the substrates required for LLO synthesis and, consequently, impair production of the final LLO donor. Increasing hexokinase activity by overexpressing hexokinase II in MI5-4 caused a decrease in the relative quantities of the incomplete LLO intermediates from Man(5)GlcNAc(2)-PP-Dol through Glc(1)Man(9)GlcNAc(2)-PP-Dol, and an increase in the relative quantity of the final LLO donor, Glc(3)Man(9)GlcNAc(2)-P-P-Dol. This study suggests that metabolic engineering may be a useful strategy for improving LLO availability for use in N-glycosylation.
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Affiliation(s)
- Meredith B Jones
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, 3400 North Charles Street, Maryland Hall 221, Baltimore, MD 21218, USA.
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30
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Whitworth GE, Zandberg WF, Clark T, Vocadlo DJ. Mammalian Notch is modified by D-Xyl-alpha1-3-D-Xyl-alpha1-3-D-Glc-beta1-O-Ser: implementation of a method to study O-glucosylation. Glycobiology 2009; 20:287-99. [PMID: 19907056 DOI: 10.1093/glycob/cwp173] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Notch is a key cell surface protein receptor that is a vital component of intercellular signaling occurring during development. The O-glucosylation of the extracellular Notch epidermal growth factor-like (EGF) repeats has recently been found to play an important role in the proper functioning of Notch in Drosophila. Previous efforts to identify the fine structure of the O-glucose-containing glycan of mammalian Notch have been hindered by limitations associated with approaches used to date. Here, we report the development of an alternative strategy that can be used to study this modification from a range of different tissues. To implement this approach, we have generated standards of the D-Xyl-alpha1-3-D-Xyl-alpha1-3-D-Glc trisaccharide, isomers of this structure, as well as the d-Xyl-alpha1-3-d-Glc disaccharide found previously on secreted EGF-containing proteins of the blood coagulation cascade. Following derivatization with 8-aminopyrene-1,3,6-trisulfonate (APTS), we use these standards in capillary electrophoretic analyses of O-glycans released from Notch1 EGF repeats in conjunction with exo-alpha-xylosidase digestion. These studies collectively reveal that the O-glucose-containing glycan decorating mammalian Notch is the D-Xyl-alpha1-3-D-Xyl-alpha1-3-D-Glc trisaccharide; an assignment in accord with previous predictions. Given the demonstrated importance of this modification in the function of Notch in Drosophila, we expect that the identification of this glycan decorating mammalian Notch1 should aid studies into the functional role of O-glycosylation of mammalian Notch isoforms. Wider application of this approach should facilitate identification of other EGF-containing proteins bearing this O-glycan and aid in their study.
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Affiliation(s)
- Garrett E Whitworth
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada
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31
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Rush JS, Gao N, Lehrman MA, Matveev S, Waechter CJ. Suppression of Rft1 expression does not impair the transbilayer movement of Man5GlcNAc2-P-P-dolichol in sealed microsomes from yeast. J Biol Chem 2009; 284:19835-42. [PMID: 19494107 DOI: 10.1074/jbc.m109.000893] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To further evaluate the role of Rft1 in the transbilayer movement of Man(5)GlcNAc(2)-P-P-dolichol (M5-DLO), a series of experiments was conducted with intact cells and sealed microsomal vesicles. First, an unexpectedly large accumulation (37-fold) of M5-DLO was observed in Rft1-depleted cells (YG1137) relative to Glc(3)Man(9)GlcNAc(2)-P-P-Dol in wild type (SS328) cells when glycolipid levels were compared by fluorophore-assisted carbohydrate electrophoresis analysis. When sealed microsomes from wild type cells and cells depleted of Rft1 were incubated with GDP-[(3)H]mannose or UDP-[(3)H]GlcNAc in the presence of unlabeled GDP-Man, no difference was observed in the rate of synthesis of [(3)H]Man(9)GlcNAc(2)-P-P-dolichol or Man(9)[(3)H]GlcNAc(2)-P-P-dolichol, respectively. In addition, no difference was seen in the level of M5-DLO flippase activity in sealed wild type and Rft1-depleted microsomal vesicles when the activity was assessed by the transport of GlcNAc(2)-P-P-Dol(15), a water-soluble analogue. The entry of the analogue into the lumenal compartment was confirmed by demonstrating that [(3)H]chitobiosyl units were transferred to endogenous peptide acceptors via the yeast oligosaccharyltransferase when sealed vesicles were incubated with [(3)H]GlcNAc(2)-P-P-Dol(15) in the presence of an exogenously supplied acceptor peptide. In addition, several enzymes involved in Dol-P and lipid intermediate biosynthesis were found to be up-regulated in Rft1-depleted cells. All of these results indicate that although Rft1 may play a critical role in vivo, depletion of this protein does not impair the transbilayer movement of M5-DLO in sealed microsomal fractions prepared from disrupted cells.
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Affiliation(s)
- Jeffrey S Rush
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky 40536, USA
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32
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Kurtoglu M, Gao N, Shang J, Maher JC, Lehrman MA, Wangpaichitr M, Savaraj N, Lane AN, Lampidis TJ. Under normoxia, 2-deoxy-D-glucose elicits cell death in select tumor types not by inhibition of glycolysis but by interfering with N-linked glycosylation. Mol Cancer Ther 2008; 6:3049-58. [PMID: 18025288 DOI: 10.1158/1535-7163.mct-07-0310] [Citation(s) in RCA: 184] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In tumor cells growing under hypoxia, inhibiting glycolysis with 2-deoxy-d-glucose (2-DG) leads to cell death, whereas under normoxic conditions cells similarly treated survive. Surprisingly, here we find that 2-DG is toxic in select tumor cell lines growing under normal oxygen tension. In contrast, a more potent glycolytic inhibitor, 2-fluorodeoxy-d-glucose, shows little or no toxicity in these cell types, indicating that a mechanism other than inhibition of glycolysis is responsible for their sensitivity to 2-DG under normoxia. A clue to this other mechanism comes from previous studies in which it was shown that 2-DG interferes with viral N-linked glycosylation and is reversible by exogenous addition of mannose. Similarly, we find that 2-DG interferes with N-linked glycosylation more potently in the tumor cell types that are sensitive to 2-DG under normoxia, which can be reversed by exogenous mannose. Additionally, 2-DG induces an unfolded protein response, including up-regulation of GADD153 (C/EBP-homologous protein), an unfolded protein response-specific mediator of apoptosis, more effectively in 2-DG-sensitive cells. We conclude that 2-DG seems to be toxic in select tumor cell types growing under normoxia by inhibition of N-linked glycosylation and not by glycolysis. Because in a phase I study 2-DG is used in combination with an anticancer agent to target hypoxic cells, our results raise the possibility that in certain cases, 2-DG could be used as a single agent to selectively kill both the aerobic (via interference with glycosylation) and hypoxic (via inhibition of glycolysis) cells of a solid tumor.
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Affiliation(s)
- Metin Kurtoglu
- Department of Cell Biologoy and Anatomy, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, USA
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33
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Rush JS, Gao N, Lehrman MA, Waechter CJ. Recycling of dolichyl monophosphate to the cytoplasmic leaflet of the endoplasmic reticulum after the cleavage of dolichyl pyrophosphate on the lumenal monolayer. J Biol Chem 2007; 283:4087-93. [PMID: 18077451 DOI: 10.1074/jbc.m707067200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
During protein N-glycosylation, dolichyl pyrophosphate (Dol-P-P) is discharged in the lumenal monolayer of the endoplasmic reticulum (ER). Dol-P-P is then cleaved to Dol-P by Dol-P-P phosphatase (DPPase). Studies with the yeast mutant cwh8Delta, lacking DPPase activity, indicate that recycling of Dol-P produced by DPPase contributes significantly to the pool of Dol-P utilized for lipid intermediate biosynthesis on the cytoplasmic leaflet. Whether Dol-P formed in the lumen diffuses directly back to the cytoplasmic leaflet or is first dephosphorylated to dolichol has not been determined. Incubation of sealed ER vesicles from calf brain with acetyl-Asn-Tyr-Thr-NH(2), an N-glycosylatable peptide, to generate Dol-P-P in the lumenal monolayer produced corresponding increases in the rates of Man-P-Dol, Glc-P-Dol, and GlcNAc-P-P-Dol synthesis in the absence of CTP. No changes in dolichol kinase activity were observed. When streptolysin-O permeabilized CHO cells were incubated with an acceptor peptide, N-glycopeptide synthesis, requiring multiple cycles of the dolichol pathway, occurred in the absence of CTP. The results obtained with sealed microsomes and CHO cells indicate that Dol-P, formed from Dol-P-P, returns to the cytoplasmic leaflet where it can be reutilized for lipid intermediate biosynthesis, and dolichol kinase is not required for recycling. It is possible that the flip-flopping of the carrier lipid is mediated by a flippase, which would provide a mechanism for the recycling of Dol-P derived from Man-P-Dol-mediated reactions in N-, O-, and C-mannosylation of proteins, GPI anchor assembly, and the three Glc-P-Dol-mediated reactions in Glc(3)Man(9)GlcNAc(2)-P-P-Dol (DLO) biosynthesis.
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Affiliation(s)
- Jeffrey S Rush
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky 40536, USA
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34
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Lehrman MA. Teaching dolichol-linked oligosaccharides more tricks with alternatives to metabolic radiolabeling. Glycobiology 2007; 17:75R-85R. [PMID: 17384121 DOI: 10.1093/glycob/cwm029] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The dolichol cycle involves synthesis of the lipid-linked oligosaccharide (LLO) Glc(3)Man(9)GlcNAc(2)-P-P-dolichol (G(3)M(9)Gn(2)-P-P-Dol), transfer of G(3)M(9)Gn(2) to asparaginyl residues of nascent endoplasmic reticulum (ER) polypeptides by oligosaccharyltransferase (OT), and recycling of the resultant Dol-P-P to Dol-P for new rounds of LLO synthesis. The importance of the dolichol cycle in secretory and membrane protein biosynthesis, ER function, and human genetic disease is now widely accepted. Elucidation of the fundamental properties of the dolichol cycle in intact cells was achieved through the use of radioactive sugar precursors, typically [(3)H]-labeled or [(14)C]-labeled d-mannose, d-galactose, or d-glucosamine. However, difficulties were encountered with cells or tissues not amenable to metabolic labeling, or in experiments influenced by isotope dilution, variable rates of LLO turnover, or special culture conditions required for the use of radioactive sugars. This article will review recently developed alternatives for LLO analysis that do not rely upon metabolic labeling with radioactive precursors, and thereby circumvent these problems. New information revealed by these methods with regard to regulation, genetic disorders, and evolution of the dolichol cycle, as well as caveats of radiolabeling techniques, will be discussed.
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Affiliation(s)
- Mark A Lehrman
- Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390-9041, USA.
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