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Müller GA, Müller TD. (Patho)Physiology of Glycosylphosphatidylinositol-Anchored Proteins II: Intercellular Transfer of Matter (Inheritance?) That Matters. Biomolecules 2023; 13:994. [PMID: 37371574 DOI: 10.3390/biom13060994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 06/12/2023] [Accepted: 06/13/2023] [Indexed: 06/29/2023] Open
Abstract
Glycosylphosphatidylinositol (GPI)-anchored proteins (APs) are anchored at the outer leaflet of the plasma membrane (PM) bilayer by covalent linkage to a typical glycolipid and expressed in all eukaryotic organisms so far studied. Lipolytic release from PMs into extracellular compartments and intercellular transfer are regarded as the main (patho)physiological roles exerted by GPI-APs. The intercellular transfer of GPI-APs relies on the complete GPI anchor and is mediated by extracellular vesicles such as microvesicles and exosomes and lipid-free homo- or heteromeric aggregates, and lipoprotein-like particles such as prostasomes and surfactant-like particles, or lipid-containing micelle-like complexes. In mammalian organisms, non-vesicular transfer is controlled by the distance between donor and acceptor cells/tissues; intrinsic conditions such as age, metabolic state, and stress; extrinsic factors such as GPI-binding proteins; hormones such as insulin; and drugs such as anti-diabetic sulfonylureas. It proceeds either "directly" upon close neighborhood or contact of donor and acceptor cells or "indirectly" as a consequence of the induced lipolytic release of GPI-APs from PMs. Those displace from the serum GPI-binding proteins GPI-APs, which have retained the complete anchor, and become assembled in aggregates or micelle-like complexes. Importantly, intercellular transfer of GPI-APs has been shown to induce specific phenotypes such as stimulation of lipid and glycogen synthesis, in cultured human adipocytes, blood cells, and induced pluripotent stem cells. As a consequence, intercellular transfer of GPI-APs should be regarded as non-genetic inheritance of (acquired) features between somatic cells which is based on the biogenesis and transmission of matter such as GPI-APs and "membrane landscapes", rather than the replication and transmission of information such as DNA. Its operation in mammalian organisms remains to be clarified.
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Affiliation(s)
- Günter A Müller
- Institute for Diabetes and Obesity (IDO), Helmholtz Diabetes Center (HDC) and German Center for Diabetes Research (DZD) at the Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstraße 1, 85764 Neuherberg, Germany
| | - Timo D Müller
- Institute for Diabetes and Obesity (IDO), Helmholtz Diabetes Center (HDC) and German Center for Diabetes Research (DZD) at the Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstraße 1, 85764 Neuherberg, Germany
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Müller GA, Ussar S, Tschöp MH, Müller TD. Age-dependent membrane release and degradation of full-length glycosylphosphatidylinositol-anchored proteins in rats. Mech Ageing Dev 2020; 190:111307. [PMID: 32628941 DOI: 10.1016/j.mad.2020.111307] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 06/18/2020] [Accepted: 06/29/2020] [Indexed: 01/28/2023]
Abstract
Glycosylphosphatidylinositol (GPI)-anchored proteins (GPI-APs) are associated with the surface of eucaryotic cells only through a covalently coupled carboxy-terminal GPI glycolipid structure which is anchored at the outer leaflet of plasma membranes. This mode of membrane association may be responsible for the recent observations that full-length GPI-APs harbouring the complete GPI anchor are (i) released from isolated rat adipocytes in vitro and (ii) expressed in rat and human serum. The upregulation of the adipocyte release in response to increased cell size and blood glucose/insulin levels of the donor rats and downregulation of the expression in serum of insulin resistant and diabetic rats have been reconciled with enhanced degradation of the full-length GPI-APs released into micelle-like complexes together with (lyso) phospholipids and cholesterol by serum GPI-specific phospholipase D (GPI-PLD). Here by using a sensitive and reliable sensing method for full-length GPI-APs, which relies on surface acoustic waves propagating over microfluidic chips, the upregulation of (i) the release of the full-length GPI-APs CD73, alkaline phosphatase and CD55 from isolated adipocyte plasma membranes monitored in a "lab-on-the-chip" configuration, (ii) their release from isolated rat adipocytes into the incubation medium and (iii) the lipolytic cleavage of their GPI anchors in serum was demonstrated to increase with age (3-16 weeks) and body weight (87-477 g) of (healthy) donor rats. In contrast, the amount of full-length GPI-APs in rat serum, as determined by chip-based sensing, turned out to decline with age/body weight. These correlations suggest that age-/weight-induced alterations (in certain biophysical/biochemical characteristics) of plasma membranes are responsible for the release of full-length GPI-APs which becomes counteracted by elevated GPI-PLD activity in serum. Thus, sensitive and specific measurement of these GPI-AP-relevant parameters may be useful for monitoring of age-related cell surface changes, in general, and diseases, in particular.
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Affiliation(s)
- Günter A Müller
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center (HDC) at Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Oberschleissheim, Germany; German Center for Diabetes Research (DZD), Oberschleissheim, Germany; Department Biology I, Genetics, Ludwig-Maximilians-Universität München, Planegg, Martinsried, Germany.
| | - Siegfried Ussar
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center (HDC) at Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Oberschleissheim, Germany; German Center for Diabetes Research (DZD), Oberschleissheim, Germany; Division of Metabolic Diseases, Department of Medicine, Technische Universität München, München, Germany
| | - Matthias H Tschöp
- German Center for Diabetes Research (DZD), Oberschleissheim, Germany; Division of Metabolic Diseases, Department of Medicine, Technische Universität München, München, Germany; Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Oberschleissheim, Germany
| | - Timo D Müller
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center (HDC) at Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Oberschleissheim, Germany; German Center for Diabetes Research (DZD), Oberschleissheim, Germany; Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, Tübingen, Germany
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Müller GA, Herling AW, Stemmer K, Lechner A, Tschöp MH. Chip-based sensing for release of unprocessed cell surface proteins in vitro and in serum and its (patho)physiological relevance. Am J Physiol Endocrinol Metab 2019; 317:E212-E233. [PMID: 31039006 DOI: 10.1152/ajpendo.00079.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
To study the possibility that certain components of eukaryotic plasma membranes are released under certain (patho)physiological conditions, a chip-based sensor was developed for the detection of cell surface proteins, which are anchored at the outer leaflet of eukaryotic plasma membranes by a covalently attached glycolipid, exclusively, and might be prone to spontaneous or regulated release on the basis of their amphiphilic character. For this, unprocessed, full-length glycosylphosphatidylinositol-anchored proteins (GPI-AP), together with associated phospholipids, were specifically captured and detected by a chip- and microfluidic channel-based sensor, leading to changes in phase and amplitude of surface acoustic waves (SAW) propagating over the chip surface. Unprocessed GPI-AP in complex with lipids were found to be released from rat adipocyte plasma membranes immobilized on the chip, which was dependent on the flow rate and composition of the buffer stream. The complexes were identified in the incubation medium of primary rat adipocytes, in correlation to the cell size, and in rat as well as human serum. With rats, the measured changes in SAW phase shift, reflecting specific mass/size or amount of the unprocessed GPI-AP in complex with lipids, and SAW amplitude, reflecting their viscoelasticity, enabled the differentiation between the lean and obese (high-fat diet) state, and the normal (Wistar) and hyperinsulinemic (Zucker fatty) as well as hyperinsulinemic hyperglycemic (Zucker diabetic fatty) state. Thus chip-based sensing for complexes of unprocessed GPI-AP and lipids reveals the inherently labile anchorage of GPI-AP at plasma membranes and their susceptibility for release in response to (intrinsic/extrinsic) cues of metabolic relevance and may, therefore, be useful for monitoring of (pre-)diabetic disease states.
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Affiliation(s)
- Günter A Müller
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München , Neuherberg , Germany
| | - Andreas W Herling
- Sanofi Deutschland GmbH, Diabetes Research Division , Frankfurt am Main , Germany
| | - Kerstin Stemmer
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München , Neuherberg , Germany
| | - Andreas Lechner
- Diabetes Research Group, Medizinische Klinik IV, Medical Center, Ludwig-Maximilians-Universität München (Klinikum der Universität München) , München , Germany
- Clinical Cooperation Group Type 2 Diabetes, Helmholtz Zentrum München, Oberschleissheim/Neuherberg, Germany
| | - Matthias H Tschöp
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München , Neuherberg , Germany
- Division of Metabolic Diseases, Department of Medicine, Technische Universität München , München , Germany
- German Center for Diabetes Research, Oberschleissheim/Neuherberg, Germany
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Müller GA. The release of glycosylphosphatidylinositol-anchored proteins from the cell surface. Arch Biochem Biophys 2018; 656:1-18. [DOI: 10.1016/j.abb.2018.08.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/07/2018] [Accepted: 08/14/2018] [Indexed: 12/15/2022]
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Bouwens EAM, Stavenuiter F, Mosnier LO. Cell painting with an engineered EPCR to augment the protein C system. Thromb Haemost 2015; 114:1144-55. [PMID: 26272345 DOI: 10.1160/th15-01-0079] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 06/28/2015] [Indexed: 11/05/2022]
Abstract
The protein C (PC) system conveys beneficial anticoagulant and cytoprotective effects in numerous in vivo disease models. The endothelial protein C receptor (EPCR) plays a central role in these pathways as cofactor for PC activation and by enhancing activated protein C (APC)-mediated protease-activated receptor (PAR) activation. During inflammatory disease, expression of EPCR on cell membranes is often diminished thereby limiting PC activation and APC's effects on cells. Here a caveolae-targeting glycosylphosphatidylinositol (GPI)-anchored EPCR (EPCR-GPI) was engineered to restore EPCR's bioavailability via "cell painting." The painting efficiency of EPCR-GPI on EPCR-depleted endothelial cells was time- and dose-dependent. The EPCR-GPI bioavailability after painting was long lasting since EPCR surface levels reached 400 % of wild-type cells after 2 hours and remained > 200 % for 24 hours. EPCR-GPI painting conveyed APC binding to EPCR-depleted endothelial cells where EPCR was lost due to shedding or shRNA. EPCR painting normalised PC activation on EPCR-depleted cells indicating that EPCR-GPI is functional active on painted cells. Caveolin-1 lipid rafts were enriched in EPCR after painting due to the GPI-anchor targeting caveolae. Accordingly, EPCR painting supported PAR1 and PAR3 cleavage by APC and augmented PAR1-dependent Akt phosphorylation by APC. Thus, EPCR-GPI painting achieved physiological relevant surface levels on endothelial cells, restored APC binding to EPCR-depleted cells, supported PC activation, and enhanced APC-mediated PAR cleavage and cytoprotective signalling. Therefore, EPCR-GPI provides a novel tool to restore the bioavailability and functionality of EPCR on EPCR- depleted and -deficient cells.
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Affiliation(s)
| | | | - Laurent O Mosnier
- Laurent O. Mosnier, Department of Molecular and Experimental Medicine (MEM-180), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA, 92037, USA, Tel.: +1 858 784 8220, Fax: +1 858 784 2243, E-mail:
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Catherman AD, Durbin KR, Ahlf DR, Early BP, Fellers RT, Tran JC, Thomas PM, Kelleher NL. Large-scale top-down proteomics of the human proteome: membrane proteins, mitochondria, and senescence. Mol Cell Proteomics 2013; 12:3465-73. [PMID: 24023390 PMCID: PMC3861700 DOI: 10.1074/mcp.m113.030114] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 09/05/2013] [Indexed: 01/25/2023] Open
Abstract
Top-down proteomics is emerging as a viable method for the routine identification of hundreds to thousands of proteins. In this work we report the largest top-down study to date, with the identification of 1,220 proteins from the transformed human cell line H1299 at a false discovery rate of 1%. Multiple separation strategies were utilized, including the focused isolation of mitochondria, resulting in significantly improved proteome coverage relative to previous work. In all, 347 mitochondrial proteins were identified, including ~50% of the mitochondrial proteome below 30 kDa and over 75% of the subunits constituting the large complexes of oxidative phosphorylation. Three hundred of the identified proteins were found to be integral membrane proteins containing between 1 and 12 transmembrane helices, requiring no specific enrichment or modified LC-MS parameters. Over 5,000 proteoforms were observed, many harboring post-translational modifications, including over a dozen proteins containing lipid anchors (some previously unknown) and many others with phosphorylation and methylation modifications. Comparison between untreated and senescent H1299 cells revealed several changes to the proteome, including the hyperphosphorylation of HMGA2. This work illustrates the burgeoning ability of top-down proteomics to characterize large numbers of intact proteoforms in a high-throughput fashion.
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Affiliation(s)
- Adam D. Catherman
- From the ‡Departments of Chemistry and Molecular Biosciences, the Chemistry of Life Processes Institute, the Proteomics Center of Excellence, and the Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Evanston, Illinois 60208
| | - Kenneth R. Durbin
- From the ‡Departments of Chemistry and Molecular Biosciences, the Chemistry of Life Processes Institute, the Proteomics Center of Excellence, and the Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Evanston, Illinois 60208
| | - Dorothy R. Ahlf
- From the ‡Departments of Chemistry and Molecular Biosciences, the Chemistry of Life Processes Institute, the Proteomics Center of Excellence, and the Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Evanston, Illinois 60208
| | - Bryan P. Early
- From the ‡Departments of Chemistry and Molecular Biosciences, the Chemistry of Life Processes Institute, the Proteomics Center of Excellence, and the Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Evanston, Illinois 60208
| | - Ryan T. Fellers
- From the ‡Departments of Chemistry and Molecular Biosciences, the Chemistry of Life Processes Institute, the Proteomics Center of Excellence, and the Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Evanston, Illinois 60208
| | - John C. Tran
- From the ‡Departments of Chemistry and Molecular Biosciences, the Chemistry of Life Processes Institute, the Proteomics Center of Excellence, and the Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Evanston, Illinois 60208
| | - Paul M. Thomas
- From the ‡Departments of Chemistry and Molecular Biosciences, the Chemistry of Life Processes Institute, the Proteomics Center of Excellence, and the Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Evanston, Illinois 60208
| | - Neil L. Kelleher
- From the ‡Departments of Chemistry and Molecular Biosciences, the Chemistry of Life Processes Institute, the Proteomics Center of Excellence, and the Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Evanston, Illinois 60208
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Müller G. Novel applications for glycosylphosphatidylinositol-anchored proteins in pharmaceutical and industrial biotechnology. Mol Membr Biol 2011; 28:187-205. [PMID: 21413835 DOI: 10.3109/09687688.2011.562557] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Glycosylphosphatidylinositol (GPI)-anchored proteins have been regarded as typical cell surface proteins found in most eukaryotic cells from yeast to man. They are embedded in the outer plasma membrane leaflet via a carboxy-terminally linked complex glycolipid GPI structure. The amphiphilic nature of the GPI anchor, its compatibility with the function of the attached protein moiety and the capability of GPI-anchored proteins for spontaneous insertion into and transfer between artificial and cellular membranes initially suggested their potential for biotechnological applications. However, these expectations have been hardly fulfilled so far. Recent developments fuel novel hopes with regard to: (i) Automated online expression, extraction and purification of therapeutic proteins as GPI-anchored proteins based on their preferred accumulation in plasma membrane lipid rafts, (ii) multiplex custom-made protein chips based on GPI-anchored cell wall proteins in yeast, (iii) biomaterials and biosensors with films consisting of sets of distinct GPI-anchored binding-proteins or enzymes for sequential or combinatorial catalysis, and (iv) transport of therapeutic proteins across or into relevant tissue cells, e.g., enterocytes or adipocytes. Latter expectations are based on the demonstrated translocation of GPI-anchored proteins from plasma membrane lipid rafts to cytoplasmic lipid droplets and eventually further into microvesicles which upon release from donor cells transfer their GPI-anchored proteins to acceptor cells. The value of these technologies, which are all based on the interaction of GPI-anchored proteins with membranes and surfaces, for the engineering, production and targeted delivery of biomolecules for a huge variety of therapeutic and biotechnological purposes should become apparent in the near future.
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Affiliation(s)
- Günter Müller
- Department Biology I, Genetics, Biocenter, Ludwig-Maximilians-University Munich, 82152 Martinsried near Munich, Germany.
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Müller G, Jung C, Wied S, Biemer-Daub G, Frick W. Transfer of the glycosylphosphatidylinositol-anchored 5'-nucleotidase CD73 from adiposomes into rat adipocytes stimulates lipid synthesis. Br J Pharmacol 2010; 160:878-91. [PMID: 20590586 PMCID: PMC2935995 DOI: 10.1111/j.1476-5381.2010.00724.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2009] [Revised: 11/13/2009] [Accepted: 12/13/2009] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND AND PURPOSE In addition to predominant localization at detergent-insoluble, glycolipid-enriched plasma membrane microdomains (DIGs), glycosylphosphatidylinositol (GPI)-anchored proteins (GPI-proteins) have been found associated with lipid droplets (LDs) and adiposomes. Adiposomes are vesicles that are released from adipocytes in response to anti-lipolytic and lipogenic signals, such as H(2)O(2), palmitate and the antidiabetic sulfonylurea drug, glimepiride, and harbour (c)AMP-degrading GPI-proteins, among them the 5-nucleotidase CD73. Here the role of adiposomes in GPI-protein-mediated information transfer was studied. EXPERIMENTAL APPROACH Adiposomes were incubated with isolated rat adipocytes under various conditions. Trafficking of CD73 and lipid synthesis were analysed. KEY RESULTS Upon blockade of GPI-protein trafficking, CD73 specifically associated with DIGs of small, and to a lower degree, large, adipocytes. On reversal of the blockade, CD73 appeared at cytosolic LD in time- adiposome concentration- and signal (H(2)O(2) > glimepiride > palmitate)-dependent fashion. The salt- and carbonate-resistant association of CD73 with structurally intact DIGs and LD was dependent on its intact GPI anchor. Upon incubation with small and to a lower degree, large adipocytes, adiposomes increased lipid synthesis in the absence or presence of H(2)O(2), glimepiride and palmitate and improved the sensitivity toward these signals. Upregulation of lipid synthesis by adiposomes was dependent on the translocation of CD73 with intact GPI anchors from DIGs to LD. CONCLUSIONS The signal-induced transfer of GPI-anchored CD73 from adiposomes via DIGs to LD of adipocytes mediates paracrine upregulation of lipid synthesis within the adipose tissue.
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Affiliation(s)
- G Müller
- Sanofi-Aventis Germany GmbH, Research & Development, Therapeutic Department Metabolism, Frankfurt am Main, Germany.
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Müller G, Wied S, Jung C, Frick W, Biemer-Daub G. Inhibition of lipolysis by adiposomes containing glycosylphosphatidylinositol-anchored Gce1 protein in rat adipocytes. Arch Physiol Biochem 2010; 116:28-41. [PMID: 20053127 DOI: 10.3109/13813450903508812] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Small membrane vesicles released from large adipocytes and harbouring the glycosylphosphatidylinositol-anchored (GPI-) AMP-degrading protein CD73 have previously been demonstrated to stimulate the signal-induced esterification of free fatty acids into neutral lipids suggesting a role of these so-called adiposomes (ADIP) in the paracrine regulation of lipid metabolism in the adipose tissue. Here the involvement of another constituent GPI-protein of ADIP, the cAMP-degrading protein Gce1 in the signal-induced inhibition of lipolysis was investigated in primary rat adipocytes. Incubation of small, and to a lower degree, large adipocytes with ADIP inhibited lipolysis and increased its sensitivity toward inhibition by H(2)O(2), the anti-diabetic drug glimepiride and palmitate. This was accompanied by the transfer of Gce1 from the ADIP to detergent-insoluble glycolipid-enriched plasma membrane microdomains (DIGs) and its subsequent translocation to cytoplasmic lipid droplets (LD) of the acceptor adipocytes. The translocation from DIGs to LD rather than the transfer from ADIP to DIGs of Gce1 was stimulated by H(2)O(2) > glimepiride > palmitate. Both transfer and translocation led to salt- and carbonate-resistant association of Gce1 with DIGs and LD, respectively, and relied on the structural integrity of the DIGs and GPI anchor of Gce1. In conclusion, the trafficking of GPI-proteins from ADIP of donor adipocytes via DIGs to LD of acceptor adipocytes mediates paracrine regulation of lipolysis within adipose tissue.
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Abstract
Transmissible spongiform encephalopathies (TSEs) are inevitably lethal neurodegenerative diseases that affect humans and a large variety of animals. The infectious agent responsible for TSEs is the prion, an abnormally folded and aggregated protein that propagates itself by imposing its conformation onto the cellular prion protein (PrPC) of the host. PrPCis necessary for prion replication and for prion-induced neurodegeneration, yet the proximal causes of neuronal injury and death are still poorly understood. Prion toxicity may arise from the interference with the normal function of PrPC, and therefore, understanding the physiological role of PrPCmay help to clarify the mechanism underlying prion diseases. Here we discuss the evolution of the prion concept and how prion-like mechanisms may apply to other protein aggregation diseases. We describe the clinical and the pathological features of the prion diseases in human and animals, the events occurring during neuroinvasion, and the possible scenarios underlying brain damage. Finally, we discuss potential antiprion therapies and current developments in the realm of prion diagnostics.
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Notohamiprodjo M, Djafarzadeh R, Mojaat A, von Lüttichau I, Gröne HJ, Nelson PJ. Generation of GPI-linked CCL5 based chemokine receptor antagonists for the suppression of acute vascular damage during allograft transplantation. Protein Eng Des Sel 2005; 19:27-35. [PMID: 16251221 DOI: 10.1093/protein/gzi072] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Limiting the acute vascular damage associated with leukocyte infiltration is a central issue in solid organ transplantation. The family of chemotactic cytokines (chemokines) helps to regulate leukocyte recruitment. Systemic treatment with the chemokine ligand-5 (CCL5) based antagonist Met-RANTES has previously shown to suppress acute damage to transplanted kidneys by blocking effector cell recruitment. To address problems associated with systemic long-term administration of chemokine receptor antagonists, a chemokine based reagent was designed to be integrated into endothelial surfaces of the organ just before transplantation. Proteins anchored by glycosylphosphatidylinositol (GPI), when purified and added to cells, are efficiently incorporated into their cell surface membranes. A series of modifications were introduced into the CCL5 protein to generate a functional antagonist. These included the addition of an N-terminal methionine group, a mutation to render the protein a dimer and a GPI signal sequence for surface expression. The resultant protein was stably expressed in CHO cells, GPI anchorage was confirmed and the protein purified by FPLC. Exogenously administered Met-CCL5(dimer)-GPI was efficiently inserted into the membrane of microvascular endothelial cells. The reagent is being tested in murine models of renal transplantation. The effect on subsequent immune induced damage will be assessed.
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Affiliation(s)
- Mike Notohamiprodjo
- Medizinische Poliklinik, Schillerstrasse 42, 80336 Ludwig-Maximilians-University of Munich, Kölnerplatz 1, 80803 Munich, German Cancer Research Center, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
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Prion diseases. NEURODEGENER DIS 2005. [DOI: 10.1017/cbo9780511544873.037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Roucou X, LeBlanc AC. Cellular prion protein neuroprotective function: implications in prion diseases. J Mol Med (Berl) 2004; 83:3-11. [PMID: 15645198 DOI: 10.1007/s00109-004-0605-5] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2004] [Accepted: 09/10/2004] [Indexed: 10/26/2022]
Abstract
Prion protein can display two conformations: a normal cellular conformation (PrP) and a pathological conformation associated with prion diseases (PrP(Sc)). Three complementary strategies are used by researchers investigating how PrP is involved in the pathogenesis of prion diseases: elucidation of the normal function of PrP, determination of how PrP(Sc) is toxic to neurons, and unraveling the mechanism for the conversion of PrP to PrP(Sc). We review the normal function of PrP as an antioxidant and an antiapoptotic protein in vivo and in vitro. This review also addresses contrasting evidence that PrP is cytotoxic. Finally, we discuss the implication of the neuroprotective role of PrP in prion diseases.
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Affiliation(s)
- Xavier Roucou
- Bloomfield Center for Research in Aging, Lady Davis Institute for Medical Research, 3755 Ch. Cote Ste-Catherine, Montreal, QC, H3T 1E2, Canada
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Abstract
Thy-1 (CD90) is a small GPI-anchored protein that is particularly abundant on the surface of mouse thymocytes and peripheral T cells. T cell proliferation and cytokine synthesis in response to Thy-1 cross-linking by specific mAb suggests a role for Thy-1 in mouse T lymphocyte activation. However, a physiological ligand or counterreceptor for murine Thy-1 in the lymphoid compartment has not yet been identified. Thy-1 cross-linking, in the context of strong costimulatory signaling through CD28, results in an activating signal that can at least partially substitute for TCR signaling during mouse T cell activation. Remarkably, Thy-1 cross-linking also results in the potent costimulation of T cells activated through the TCR. This novel dual signaling capacity suggests a possible role for Thy-1 in the maintenance of T cell homeostasis in the absence of TCR triggering, as well as potentiating Ag-induced T cell responses.
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Affiliation(s)
- S M Mansour Haeryfar
- Cellular Biology and Viral Immunology Sections, Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD 20892, USA.
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Eisenhaber B, Maurer-Stroh S, Novatchkova M, Schneider G, Eisenhaber F. Enzymes and auxiliary factors for GPI lipid anchor biosynthesis and post-translational transfer to proteins. Bioessays 2003; 25:367-85. [PMID: 12655644 DOI: 10.1002/bies.10254] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
GPI lipid anchoring is an important post-translational modification of eukaryote proteins in the endoplasmic reticulum. In total, 19 genes have been directly implicated in the anchor synthesis and the substrate protein modification pathway. Here, the molecular functions of the respective proteins and their evolution are analyzed in the context of reported literature data and sequence analysis studies for the complete pathway (http://mendel.imp.univie.ac.at/SEQUENCES/gpi-biosynthesis/) and questions for future experimental investigation are discussed. Studies of two of these proteins have provided new mechanistic insights. The cytosolic part of PIG-A/GPI3 has a two-domain alpha/beta/alpha-layered structure; it is suggested that its C-terminal subsegment binds UDP-GlcNAc whereas the N-terminal domain interacts with the phosphatidylinositol moiety. The lumenal part of PIG-T/GPI16 apparently consists of a beta-propeller with a central hole that regulates the access of substrate protein C termini to the active site of the cysteine protease PIG-K/GPI8 (gating mechanism) as well as of a polypeptide hook that embraces PIG-K/GPI8. This structural proposal would explain the paradoxical properties of the GPI lipid anchor signal motif and of PIG-K/GPI8 orthologs without membrane insertion regions in some species.
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Affiliation(s)
- Birgit Eisenhaber
- Research Institute of Molecular Pathology, Dr. Bohr-Gasse 7, A-1030 Vienna, Republic Austria
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Abstract
For more than two decades it has been contended that prion infection does not elicit immune responses: transmissible spongiform encephalopathies do not go along with conspicuous inflammatory infiltrates, and antibodies to the prion protein are typically undetectable. Why is it, then, that prions accumulate in lymphoid organs, and that various states of immune deficiency prevent peripheral prion infection? This review revisits the current evidence of the involvement of the immune system in prion diseases, while attempting to trace the elaborate mechanisms by which peripherally administered prions invade the brain and ultimately cause damage. The investigation of these questions leads to unexpected detours, including the neurophysiology of lymphoid organs, and even the function of a prion protein homolog in male fertility.
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Affiliation(s)
- Adriano Aguzzi
- Institute of Neuropathology, Universitätsspital Zürich, Schmelzbergstrasse 12, CH-8091 Zürich, Switzerland.
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Aguzzi A, Heppner FL, Heikenwalder M, Prinz M, Mertz K, Seeger H, Glatzel M. Immune system and peripheral nerves in propagation of prions to CNS. Br Med Bull 2003; 66:141-59. [PMID: 14522856 DOI: 10.1093/bmb/66.1.141] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Prions are not only unique in the way they replicate. Also the sequence of events triggered by peripheral prion infection, generically termed 'peripheral pathogenesis', sets prions aside from all other known pathogens. Whereas most bacteria, parasites, and viruses trigger innate and adaptive immune responses, the mammalian immune system appears to be remarkably oblivious to prions. Transmissible spongiform encephalopathies (TSEs) do not go along with inflammatory infiltrates, and antibodies to the prion protein are not typically raised during the course of the disease. On the other hand, there is conspicuous involvement of lymphoid organs, which accumulate sizeable concentrations of the infectious agent early during disease. Moreover, various states of immune deficiency can abolish peripheral pathogenesis and prevent 'take' of infection when prions are administered to peripheral sites. Here, we critically re-visit the current evidence for an involvement of the immune system in prion diseases, and will attempt to trace the elaborate mechanisms by which prions, upon entry into the body from peripheral sites, reach the brain.
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Affiliation(s)
- Adriano Aguzzi
- Institute of Neuropathology, Universitätsspital Zürich, Switzerland
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Gatti JL, Métayer S, Moudjou M, Andréoletti O, Lantier F, Dacheux JL, Sarradin P. Prion protein is secreted in soluble forms in the epididymal fluid and proteolytically processed and transported in seminal plasma. Biol Reprod 2002; 67:393-400. [PMID: 12135872 DOI: 10.1095/biolreprod67.2.393] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The presence of prion protein in sperm and fluids collected from different parts of the ram genital tract was investigated by immunoblotting with monoclonal antibodies. A slightly immunoreactive 25- to 30-kDa protein was recognized on Western blots of testicular and epididymal sperm extracts. Immunoreactivity increased on ejaculated sperm extracts and 2 other bands at 35 and 43 kDa also reacted. Seminal plasma showed several immunoreactive bands, the main bands being detected at 43 and 35 kDa, whereas less reactive bands were observed at 30, 25, 20, and <14 kDa. All these bands strongly decreased in the seminal plasma after vasectomy, indicating a testicular or an epididymal origin. Testicular fluid showed almost no reactivity, whereas caudal epididymal fluid contained the 2 strong immunoreactive bands at 43 and 35 kDa and in some cases a faint 30-kDa band. The 43-kDa band was also found in the fluid from the proximal caput, whereas the 35-kDa band appeared in the distal caput. Immunoprecipitation of (35)S-labeled proteins secreted in the epididymal fluid indicated that the 43-kDa form was synthesized in caput and caudal regions and the 35-kDa form in the distal caput to the distal corpus. Treatment of caudal fluid and seminal plasma by N-glycosidase resulted in the formation of 3 bands: 1 highly reactive at about 25 kDa, a second less reactive at about 28 kDa, and a third at approximately 20 kDa. The pattern of prion protein distribution in epididymal fluids was found to be similar in scrapie-infected rams to that of healthy rams. Cauda epididymal fluid and seminal plasma from infected animals could not be treated directly with proteinase K, because of the presence of protease inhibitors. However, the prion protein immunoprecipitated from these fluids was completely cleaved by proteinase K, whereas in the same conditions this from an infected sheep brain gave the usual resistant band pattern.
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Affiliation(s)
- Jean-Luc Gatti
- Equipe Spermatozoïdes, Station de Pathologie Infectieuse et Immunologie, Institut National de la Recherche Agronomique, INRA Nouzilly, 37380 Monnaie, France.
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Hiscox S, Hallett MB, Morgan BP, van den Berg CW. GPI-anchored GFP signals Ca2+ but is homogeneously distributed on the cell surface. Biochem Biophys Res Commun 2002; 293:714-21. [PMID: 12054528 DOI: 10.1016/s0006-291x(02)00280-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Glycosyl-phosphatidylinositol (GPI)-anchored proteins are unique in that they penetrate only the outer leaflet of the plasma membrane but are still able to mediate intracellular signalling events following antibody-induced ligation. Detergent solubilisation studies suggest that microdomains exist at the cell surface within which are sequestered GPI-linked proteins. Here we report the construction and expression of a fluorescent GPI anchor on the surface of CHO, EL4, and U937 cells by fusing green fluorescent protein (GFP) to the GPI-attachment site of CD59. The resultant GFP-GPI has properties comparable to that of endogenously expressed GPI-anchored molecules as shown by Triton X-114 partitioning. However, sucrose gradient floatation showed that GFP-GPI was only partially resistant to detergent solubilisation. Furthermore confocal scanning laser microscopy revealed a homogeneous distribution of GFP-GPI at the cell surface, which only became clustered following cross-linking of the GPI anchor via an anti-GFP antibody. Surprisingly, GFP-GPI signalled Ca2+ change upon cross-linking demonstrating its signalling competence. Our results suggest that the GPI-anchor itself does not confer a clustered distribution to molecules but that clustering occurs following ligation with antibody, which allows the protein to become Ca2+ signalling competent.
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Affiliation(s)
- Stephen Hiscox
- Department of Pharmacology, Therapeutics and Toxicology, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN, UK
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Kanu N, Imokawa Y, Drechsel DN, Williamson RA, Birkett CR, Bostock CJ, Brockes JP. Transfer of scrapie prion infectivity by cell contact in culture. Curr Biol 2002; 12:523-30. [PMID: 11937020 DOI: 10.1016/s0960-9822(02)00722-4] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND When a cell is infected with scrapie prions, newly synthesized molecules of the prion protein PrP(C) are expressed at the cell surface and may subsequently be converted to the abnormal form PrP(Sc). In an experimental scrapie infection of an animal, the initial innoculum of PrP(Sc) is cleared relatively rapidly, and the subsequent propagation of the infection depends on the ability of infected cells to convert uninfected target cells to stable production of PrP(Sc). The mechanism of such cell-based infection is not understood. RESULTS We have established a system in dissociated cell culture in which scrapie-infected mouse SMB cells are able to stably convert genetically marked target cells by coculture. After coculture and rigorous removal of SMB cells, the target cells express PrP(Sc) and also incorporate [35S]methionine into PrP(Sc). The extent of conversion was sensitive to the ratio of the two cell types, and conversion by live SMB required 2500-fold less PrP(Sc) than conversion by a cell-free prion preparation. The conversion activity of SMB cells is not detectable in conditioned medium and apparently depends on close proximity or contact, as evidenced by culturing the SMB and target cells on neighboring but separate surfaces. SMB cells were killed by fixation in aldehydes, followed by washing, and were found to retain significant activity at conversion of target cells. CONCLUSIONS Cell-mediated infection of target cells in this culture system is effective and requires significantly less PrP(Sc) than infection by a prion preparation. Several lines of evidence indicate that it depends on cell contact, in particular, the activity of aldehyde-fixed infected cells.
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Affiliation(s)
- Nnennaya Kanu
- Department of Biochemistry and Molecular Biology, University College London, Gower Street, WC1E 6BT, London, United Kingdom
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Margos G, Navarette S, Butcher G, Davies A, Willers C, Sinden RE, Lachmann PJ. Interaction between host complement and mosquito-midgut-stage Plasmodium berghei. Infect Immun 2001; 69:5064-71. [PMID: 11447187 PMCID: PMC98601 DOI: 10.1128/iai.69.8.5064-5071.2001] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
After ingestion by mosquitoes, gametocytes of malaria parasites become activated and form extracellular gametes that are no longer protected by the red blood cell membrane against immune effectors of host blood. We have studied the action of complement on Plasmodium developmental stages in the mosquito blood meal using the rodent malaria parasite Plasmodium berghei and rat complement as a model. We have shown that in the mosquito midgut, rat complement components necessary to initiate the alternative pathway (factor B, factor D, and C3) as well as C5 are present for several hours following ingestion of P. berghei-infected rat blood. In culture, 30 to 50% of mosquito midgut stages of P. berghei survived complement exposure during the first 3 h of development. Subsequently, parasites became increasingly sensitive to complement lysis. To investigate the mechanisms involved in their protection, we tested for C3 deposition on parasite surfaces and whether host CD59 (a potent inhibitor of the complement membrane attack complex present on red blood cells) was taken up by gametes while emerging from the host cell. Between 0.5 and 22 h, 90% of Pbs21-positive parasites were positive for C3. While rat red and white blood cells stained positive for CD59, Pbs21-positive parasites were negative for CD59. In addition, exposure of parasites to rat complement in the presence of anti-rat CD59 antibodies did not increase lysis. These data suggest that parasite or host molecules other than CD59 are responsible for the protection of malaria parasites against complement-mediated lysis. Ongoing research aims to identify these molecules.
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Affiliation(s)
- G Margos
- Microbial Immunology Group, Centre for Veterinary Science, University of Cambridge, Cambridge CB3 0ES, United Kingdom.
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Jansen GH, Vogelaar CF, Elshof SM. Distribution of cellular prion protein in normal human cerebral cortex--does it have relevance to Creutzfeldt-Jakob disease? Clin Chem Lab Med 2001; 39:294-8. [PMID: 11388651 DOI: 10.1515/cclm.2001.045] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Creutzfeldt-Jakob disease and bovine spongiform encephalopathy are the best known forms of prion diseases. A basis for their pathogenesis is the transformation of normal prion protein to abnormal prion protein. This would mean that either loss of normal function or a gain of a toxic function of the prion protein would play a major role. Since the prime target for Creutzfeldt-Jakob disease in humans is the neocortex, and the intracortical distribution of the destructive process in prion diseases appears not to be haphazard, it may be that a clear cortical study of normal prion protein production in the premorbid human neocortex might contribute to insight in the pathogenesis of prion diseases. As no such study is available, we performed a detailed study in normal human cortex using immunohistochemistry for prion protein, in both frozen and vibratomised tissue, and in situ hybridisation for prion protein mRNA. We have found normal prion protein production mainly in the upper cortical neurons in neocortex and Purkinje cells in the cerebellum. This finding implicates that normal prion protein is more important as an anti-apoptotic signal in disease than abnormal prion protein is as a toxic substance.
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Affiliation(s)
- G H Jansen
- Department of Pathology, University Medical Center Utrecht, The Netherlands.
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