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Gu Y, Verghese S, Mishra RS, Xu X, Shi Y, Singh N. Mutant prion protein-mediated aggregation of normal prion protein in the endoplasmic reticulum: implications for prion propagation and neurotoxicity. J Neurochem 2003; 84:10-22. [PMID: 12485397 DOI: 10.1046/j.1471-4159.2003.01255.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Familial prion disorders are believed to result from spontaneous conversion of mutant prion protein (PrPM) to the pathogenic isoform (PrPSc). While most familial cases are heterozygous and thus express the normal (PrPC) and mutant alleles of PrP, the role of PrPC in the pathogenic process is unclear. Plaques from affected cases reveal a heterogeneous picture; in some cases only PrPM is detected, whereas in others both PrPC and PrPM are transformed to PrPSc. To understand if the coaggregation of PrPC is governed by PrP mutations or is a consequence of the cellular compartment of PrPM aggregation, we coexpressed PrPM and PrPC in neuroblastoma cells, the latter tagged with green fluorescent protein (PrPC-GFP) for differentiation. Two PrPM forms (PrP231T, PrP217R/231T) that aggregate spontaneously in the endoplasmic reticulum (ER) were generated for this analysis. We report that PrPC-GFP aggregates when coexpressed with PrP231T or PrP217R/231T, regardless of sequence homology between the interacting forms. Furthermore, intracellular aggregates of PrP231T induce the accumulation of a C-terminal fragment of PrP, most likely derived from a potentially neurotoxic transmembrane form of PrP (CtmPrP) in the ER. These findings have implications for prion pathogenesis in familial prion disorders, especially in cases where transport of PrPM from the ER is blocked by the cellular quality control.
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Affiliation(s)
- Yaping Gu
- Institute of Pathology, Case Western Reserve University, Cleveland, Ohio 44106, USA
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2
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Nelson KL, Brodsky RA, Buckley JT. Channels formed by subnanomolar concentrations of the toxin aerolysin trigger apoptosis of T lymphomas. Cell Microbiol 1999; 1:69-74. [PMID: 11207542 DOI: 10.1046/j.1462-5822.1999.00009.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Aerolysin is a channel-forming toxin that binds to glycosylphosphatidylinositol (GPI)-anchored proteins, such as Thy-1, on target cells. Here, we show that subnanomolar concentrations of aerolysin trigger apoptosis of T lymphomas. Using inactive aerolysin variants, we determined that apoptosis was not directly triggered by binding to GPI-anchored receptors, nor was it caused by receptor clustering induced by toxin oligomerization. Apoptosis was caused by the production of a small number of channels in the cell membrane. Channel formation resulted in a rapid increase in intracellular calcium, which may have been the signal for apoptosis. Overexpression of the antiapoptotic protein bcl-2 blocked aerolysin-induced apoptosis, although this effect was overcome at higher toxin concentrations.
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Affiliation(s)
- K L Nelson
- Department of Biochemistry and Microbiology, University of Victoria, BC, Canada
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3
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Tiede A, Bastisch I, Schubert J, Orlean P, Schmidt RE. Biosynthesis of glycosylphosphatidylinositols in mammals and unicellular microbes. Biol Chem 1999; 380:503-23. [PMID: 10384957 DOI: 10.1515/bc.1999.066] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Membrane anchoring of cell surface proteins via glycosylphosphatidylinositol (GPI) occurs in all eukaryotic organisms. In addition, GPI-related glycophospholipids are important constituents of the glycan coat of certain protozoa. Defects in GPI biosynthesis can retard, if not abolish growth of these organisms. In humans, a defect in GPI biosynthesis can cause paroxysmal nocturnal hemoglobinuria (PNH), a severe acquired bone marrow disorder. Here, we review advances in the characterization of GPI biosynthesis in parasitic protozoa, yeast and mammalian cells. The GPI core structure as well as the major steps in its biosynthesis are conserved throughout evolution. However, there are significant biosynthetic differences between mammals and microbes. First indications are that these differences could be exploited as targets in the design of novel pharmacotherapeutics that selectively inhibit GPI biosynthesis in unicellular microbes.
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Affiliation(s)
- A Tiede
- Department of Clinical Immunology, Hannover Medical School, Germany
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4
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Nosjean O, Briolay A, Roux B. Mammalian GPI proteins: sorting, membrane residence and functions. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1331:153-86. [PMID: 9325440 DOI: 10.1016/s0304-4157(97)00005-1] [Citation(s) in RCA: 156] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- O Nosjean
- Université Claude Bernard--Lyon 1, Laboratoire de Physico-chimie Biologique--UPRESA CNRS 5013, Villeurbanne, France.
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5
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Kinoshita T, Inoue N, Takeda J. Defective glycosyl phosphatidylinositol anchor synthesis and paroxysmal nocturnal hemoglobinuria. Adv Immunol 1995; 60:57-103. [PMID: 8607375 DOI: 10.1016/s0065-2776(08)60584-2] [Citation(s) in RCA: 122] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- T Kinoshita
- Department of Immunoregulation, Osaka University, Japan
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6
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Stevens VL, Zhang H. Coenzyme A dependence of glycosylphosphatidylinositol biosynthesis in a mammalian cell-free system. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(18)31707-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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7
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Field M, Moran P, Li W, Keller G, Caras I. Retention and degradation of proteins containing an uncleaved glycosylphosphatidylinositol signal. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)34134-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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8
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Characterization of abnormal free glycophosphatidylinositols accumulating in mutant lymphoma cells of classes B, E, F, and H. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)53166-5] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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9
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Tartakoff AM. Biological functions and biosynthesis of glycolipid-anchored membrane proteins. Subcell Biochem 1993; 21:81-93. [PMID: 8256275 DOI: 10.1007/978-1-4615-2912-5_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Affiliation(s)
- A M Tartakoff
- Institute of Pathology, Case Western Reserve University, Cleveland, Ohio 44106
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10
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Puoti A, Conzelmann A. Structural characterization of free glycolipids which are potential precursors for glycophosphatidylinositol anchors in mouse thymoma cell lines. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)41724-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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11
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Abstract
Essentially all eukaryotic cells express proteins on their surface that are anchored by a glycoinositol phospholipid. This anchor moiety may endow such proteins with unusual properties. The definition of the biosynthetic path that constructs these anchors is now in its final stages. Mutations that interrupt this path are, remarkably, compatible with survival of cells in culture, but are associated with at least one human disease.
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Affiliation(s)
- A M Tartakoff
- Institute of Pathology, Case Western Reserve University, Cleveland, OH 44106
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12
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Affiliation(s)
- D M Lublin
- Department of Pathology, Washington University School of Medicine, St. Louis, MO 63110
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13
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Einhorn GP, Qin L, Soloski MJ. Biosynthesis of glycophospholipid bound and secreted murine class I Qa-2 polypeptides. Mol Immunol 1991; 28:1299-310. [PMID: 1961202 DOI: 10.1016/0161-5890(91)90017-e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Murine T cells synthesize and express a cell-surface glycophospholipid anchored 40 kDa and a secreted water-soluble 39 kDa Qa-2 polypeptide. We have examined the biosynthetic pathways which lead to the production of the membrane-bound and water-soluble isoforms of the Qa-2 molecule. Using the detergent TX-114, both detergent (membrane)-bound and soluble Qa-2 polypeptides can be identified in cell lysates and can be distinguished by charge and molecular weight. Two membrane-bound forms, a 40-kDa Endo H resistant cell-surface form and a 38 kDa-Endo H sensitive form can be identified, both of which can be biosynthetically labeled with 3H-ethanolamine and can be converted to water soluble forms by digestion with a phosphatidylinositol specific phospholipase C. In addition, several water soluble polypeptides at 39, 37, 35 kDa, and a minor species at 33 kDa were identified, none of which radiolabel with 3H-ethanolamine. While the 39-kDa polypeptide was Endo H resistant, the other isoforms were sensitive to Endo H digestion. Pulse chase experiments and molecular weights of the deglycosylated core polypeptides suggest a precursor to product relationship between the intracellular water-soluble species and the mature 39-kDa secreted Qa-2 molecule. This relationship is supported by the observation that murine L cells transfected with the Qa-2 encoding class I gene Q7 fail to express membrane-bound Qa-2 molecules yet synthesize both intracellular water-soluble and secreted Qa-2 molecules. These findings argue for a pathway in which secreted soluble Qa-2 molecules are derived from intracellular precursors.
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14
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Puoti A, Desponds C, Fankhauser C, Conzelmann A. Characterization of glycophospholipid intermediate in the biosynthesis of glycophosphatidylinositol anchors accumulating in the Thy-1-negative lymphoma line SIA-b. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54819-5] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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15
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Sugiyama E, DeGasperi R, Urakaze M, Chang H, Thomas L, Hyman R, Warren C, Yeh E. Identification of defects in glycosylphosphatidylinositol anchor biosynthesis in the Thy-1 expression mutants. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)98865-4] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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16
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Stevens V, Raetz C. Defective glycosyl phosphatidylinositol biosynthesis in extracts of three Thy-1 negative lymphoma cell mutants. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)99182-9] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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17
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Déglon N, Krapp A, Bron C, Fasel N. Translocation of the yeast dolichol-phosphate-mannose synthase into microsomal membranes. Biochem Biophys Res Commun 1991; 174:1337-42. [PMID: 1996998 DOI: 10.1016/0006-291x(91)91569-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Dolichol-phosphate-mannose synthase catalyzes the formation of Dolichol-phosphate-mannose from Dolichol-phosphate and GDP-mannose. Analysis of the primary amino acid sequence of the yeast enzyme predicts a luminal orientation of the enzyme in the endoplasmic reticulum. We analysed the translocation of the Dolichol-phosphate-mannose synthase into dog pancreatic microsomal membranes: resistance to proteolytic attack provides evidence of its luminal orientation and asks for a reevaluation of the topology of the reaction.
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Affiliation(s)
- N Déglon
- Institute of Biochemistry, University of Lausanne, Epalinges, Switzerland
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18
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Kaetzel D, Singh N, Kennedy G, Virgin J, Farr G, Kitagawa Y, Nilson J, Tartakoff A. Complete and partial glycophospholipid anchors are found on a fusion protein consisting of luteinizing hormone beta subunit followed by a carboxyl-terminal domain of Thy-1. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)55487-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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19
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Stevens V, Raetz C. Class F Thy-1-negative murine lymphoma cells are deficient in ether lipid biosynthesis. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)55448-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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20
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Lisanti MP, Rodriguez-Boulan E, Saltiel AR. Emerging functional roles for the glycosyl-phosphatidylinositol membrane protein anchor. J Membr Biol 1990; 117:1-10. [PMID: 2144878 DOI: 10.1007/bf01871561] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- M P Lisanti
- Department of Cell Biology and Anatomy, Cornell University Medical College, New York, New York
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21
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Low MG. The glycosyl-phosphatidylinositol anchor of membrane proteins. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 988:427-54. [PMID: 2531614 DOI: 10.1016/0304-4157(89)90014-2] [Citation(s) in RCA: 383] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- M G Low
- Department of Physiology and Cellular Biophysics, College of Physicians and Surgeons, Columbia University, New York 10032
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22
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Rock KL, Reiser H, Bamezai A, McGrew J, Benacerraf B. The LY-6 locus: a multigene family encoding phosphatidylinositol-anchored membrane proteins concerned with T-cell activation. Immunol Rev 1989; 111:195-224. [PMID: 2697681 DOI: 10.1111/j.1600-065x.1989.tb00547.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- K L Rock
- Division of Lymphocyte Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115
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23
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Gupta D, Tartakoff A, Tisdale E. Metabolic correction of defects in the lipid anchoring of Thy-1 in lymphoma mutants. Science 1988; 242:1446-8. [PMID: 2904699 DOI: 10.1126/science.2904699] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Many plasma membrane proteins, including Thy-1, are anchored by a carboxyl terminal glycophospholipid. This unit is absent from the Thy-1 of several lymphoma mutants that synthesize the Thy-1 polypeptide but fail to express it at the cell surface. Recessive mutants of complementation groups A to C, E, and F contain Thy-1 mRNA of normal size, which suggests that their Thy-1 polypeptide is normal. To identify possible metabolic lesions, each mutant was grown with various supplements. The class F and B mutants exhibited a reversible induction of surface lipid anchored Thy-1 when grown with the aminoglycoside G418. Other aminoglycosides, sugars, and ethanolamine were inactive. These unexpected observations are discussed in the context of lipid anchor biosynthesis.
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Affiliation(s)
- D Gupta
- Department of Pathology, Case Western Reserve University, Cleveland, OH 44106
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24
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Tisdale EJ, Tartakoff AM. Extensive labeling with [3H]ethanolamine of a hydrophilic protein of animal cells. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)68470-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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25
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Abstract
Glycosylated forms of phosphatidylinositol, which have only recently been described in eukaryotic organisms, are now known to play important roles in biological membrane function. These molecules can serve as the sole means by which particular cell-surface proteins are anchored to the membrane. Lipids with similar structures may also be involved in signal transduction mechanisms for the hormone insulin. The utilization of this novel class of lipid molecules for these two distinct functions suggests new mechanisms for the regulation of proteins in biological membranes.
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Affiliation(s)
- M G Low
- Department of Physiology and Cellular Biophysics, College of Physicians and Surgeons of Columbia University, New York, NY 10032
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