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Gardner DR, Lee ST, Molyneux RJ, Edgar JA. Preparative isolation of swainsonine from locoweed: extraction and purification procedures. PHYTOCHEMICAL ANALYSIS : PCA 2003; 14:259-266. [PMID: 12892424 DOI: 10.1002/pca.713] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The trihydroxy indolizidine alkaloid swainsonine, a plant toxin with potent alpha-mannosidase-inhibitory activity and chemotherapeutic potential, was isolated in gram quantities from locoweed (Astragalus lentiginosus). The key isolation and purification step was a continuous liquid/liquid extraction procedure using dichloromethane to extract a basified aqueous methanol solution obtained after isolation of the polar base fraction by ion-exchange. The concentration of swainsonine was increased from ca. 7% in the polar base material to 68% using the liquid/liquid extraction procedure. Pure swainsonine was then obtained by recrystallisation from ammonia-saturated chloroform or by sublimation. Small samples of swainsonine were also purified by formation of the chloroform-soluble methylboronate derivative, from which the alkaloid could be regenerated easily by hydrolysis.
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Affiliation(s)
- Dale R Gardner
- Poisonous Plant Research Laboratory, Agricultural Research Service, USDA,1150 E. 1400 N., Logan, UT 84341, USA.
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2
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Elbein AD. The Use of Glycosylation Inhibitors to Study Glycoconjugate Function. CELL SURFACE AND EXTRACELLULAR GLYCOCONJUGATES 1993. [PMCID: PMC7155559 DOI: 10.1016/b978-0-12-589630-6.50009-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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3
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Overdijk B, Beem EP, Van der Wal CJ, Jongenelen CA. Lysosomal beta-hexosaminidase is highly resistant towards proteolytic degradation in vitro. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1992; 24:1793-800. [PMID: 1451915 DOI: 10.1016/0020-711x(92)90130-s] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
1. A partially purified enzyme preparation of beta-hexosaminidase from human fibroblasts was treated with proteases and the effect on its molecular weight and enzymatic activity was studied. 2. Both the forms A and B of the enzyme appeared to be resistant to a protease treatment that degraded the majority of the contaminating proteins to a large extent. 3. The same result was obtained with enzyme preparations from cells treated with tunicamycin. 4. Also the molecular weights of the individual polypeptide chains of the enzyme were not decreased, as was shown by SDS-PAGE, followed by immuno-blotting.
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Affiliation(s)
- B Overdijk
- Department of Medical Chemistry, Faculty of Medicine, Vrije Universiteit, Amsterdam, The Netherlands
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Jans DA, Jans P, Luzius H, Fahrenholz F. N-glycosylation plays a role in biosynthesis and internalization of the adenylate cyclase stimulating vasopressin V2-receptor of LLC-PK1 renal epithelial cells: an effect of concanavalin A on binding and expression. Arch Biochem Biophys 1992; 294:64-9. [PMID: 1532296 DOI: 10.1016/0003-9861(92)90137-l] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The role of N-glycosylation in the function and biosynthesis of the vasopressin V2-receptor in LLC-PK1 renal epithelial cells was examined using various lectins and inhibitors operating at different steps of the glycosidic pathway. Tunicamycin, which blocks all N-glycosylation, and castanospermine, which inhibits glycosidase I and hence blocks formation of high-mannose-type N-glycosylated intermediates, resembled one another in affecting V2-receptor biosynthesis and internalization in a concentration-dependent manner. In contrast, swainsonine, an inhibitor of mannosidase II and hence of complex-type oligosaccharide formation, had no effect. Interestingly, the alpha-D-mannose/alpha-D-glucose-specific lectin concanavalin A, (Con A), in contrast to the beta-D-galactose-specific lectin ricin, had a marked effect on the V2-receptor in LLC-PK1 cells, increasing both receptor numbers up to twofold in vivo and specific [3H]AVP binding up to 50% in vitro in a concentration-dependent manner. The concentrations inducing half-maximal response were about 0.2 and 20 micrograms/ml for the in vivo and in vitro responses, respectively, implying distinct effects on V2-expression and ligand binding. That the in vitro effect on binding was due to a direct effect on the V2-receptor could be shown by the lack of a Con A effect on [3H]AVP binding in membranes prepared from LLC-PK1 cells down-regulated for the V2-receptor or from cells of the LLC-PK1 V2-receptor deficient mutant M18. All results were consistent with a functional role for N-glycosylation of the V2-receptor in LLC-PK1 cells.
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Affiliation(s)
- D A Jans
- Max-Planck-Institut für Biophysik, Frankfurt am Main, FRG
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Glycosidase and Glycosyltransferase Inhibitors. ACTA ACUST UNITED AC 1992. [DOI: 10.1016/b978-0-444-89558-5.50038-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
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6
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Sano A, Taylor ME, Leaning MS, Summerfield JA. Uptake and processing of glycoproteins by isolated rat hepatic endothelial and Kupffer cells. J Hepatol 1990; 10:211-6. [PMID: 2332592 DOI: 10.1016/0168-8278(90)90054-u] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Mannose-(Man) and N-acetylglucosamine- (GlcNAc)-terminated glycoproteins are cleared from blood by carbohydrate-specific receptors present on both hepatic endothelial and Kupffer cells. It is not known whether the same receptors are present on each cell type or the relative contributions to glycoprotein metabolism made by Kupffer and endothelial cells. Here we report experiments where data from glycoprotein metabolism by purified populations of isolated rat hepatic endothelial and Kupffer cells have been analyzed by mathematical modelling and parameter estimation. Kupffer cells had significantly higher binding rate constants (k'21) than endothelial cells for agalactoorosomucoid (AGOR) and hyaluronidase, but lower k12 ('off-rate') indicating that Kupffer cells had higher affinities for Man/GlcNAc-terminated glycoproteins than endothelial receptors. Furthermore, although endothelial cells had similar affinities (k'21 and k12) for AGOR and hyaluronidase, the 'off-rate' of Kupffer cells was significantly greater for AGOR than for hyaluronidase, indicating that Kupffer cell receptors have lower affinity for AGOR. Internalization and ligand catabolic rates also differed between the two cell types. The data indicate that Kupffer and endothelial cells appear to have different Man/GlcNAc receptors and that the destination of a glycoprotein and its subsequent processing is determined by the structure of a glycoprotein's oligosaccharide.
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Affiliation(s)
- A Sano
- Medical Unit, St Marys Hospital Medical School, London, U.K
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Mareel MM, De Mets M. Anti-invasive activities of experimental chemotherapeutic agents. Crit Rev Oncol Hematol 1989; 9:263-303. [PMID: 2686699 DOI: 10.1016/s1040-8428(89)80004-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
We have discussed a number of agents that affect invasion and we have grouped them according to their most probable targets. This strategy is based on the following hypothesis. Invasion is the result of cellular responses to extracellular signals. Candidate signals are components of the extracellular matrix, which are rendered inactive by the flavonoid (+)-catechin (see Section III). Signals are recognized by receptors on the plasma membrane, possibly glycoproteins, that may lose their recognition function through alteration of the oligosaccharide side chains by inhibitors of protein glycosylation (see Section IV) and possibly also by alkyllysophospholipids (see Section V). Synthetic oligopeptides reflecting sequences from cell-binding domains of extracellular matrix molecules are also effective tools for blocking specific receptors (see Section VI). GTP-binding proteins (G proteins) act as signal transducers and can be inactivated by pertussis toxin (see Section VII). An intriguing aspect of both alkyllysophospholipids and pertussis toxin is that they can either inhibit the invasion of constitutively invasive cells or induce invasion of constitutively noninvasive cells. Without doubt, cellular responses implicated in invasion are many-fold. Discussed here are cell motility and directional migration with inhibition through dipyridamole and its analogs and through microtubule inhibitors, respectively (see Section VIII). Alternative hypotheses and alternative strategies for the dissection of the invasion process do exist, and alternative cellular and molecular mechanisms of action may explain the anti-invasive activity of the agents discussed earlier. The latter are mentioned in each section. It is the authors' opinion that the possibilities for exploiting the battery of anti-invasive agents have by no means been exhausted. Introducing researchers to experiments that may lead to an understanding of the mechanisms of invasion and metastasis and to new rationales for cancer treatment has been the purpose of our review.
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Affiliation(s)
- M M Mareel
- Department of Radiotherapy and Nuclear Medicine, University Hospital, Ghent, Belgium
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Caro LH, Plomp PJ, Wolvetang EJ, Kerkhof C, Meijer AJ. 3-Methyladenine, an inhibitor of autophagy, has multiple effects on metabolism. EUROPEAN JOURNAL OF BIOCHEMISTRY 1988; 175:325-9. [PMID: 3402459 DOI: 10.1111/j.1432-1033.1988.tb14200.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
3-Methyladenine is generally used as an inhibitor of autophagy [P. O. Seglen & P. B. Gordon (1982) Proc. Natl Acad. Sci. USA 79, 1889-1892]. Using isolated hepatocytes, we observed that 3-methyladenine has other effects as well. 1. 3-Methyladenine promoted glycogen breakdown and inhibited flux through phosphofructokinase and pyruvate kinase. These effects proved to be unrelated to inhibition of autophagic proteolysis and were caused by cAMP, which slightly increased in the presence of 3-methyladenine. 2. Addition of 3-methyladenine to intact hepatocytes increased the intralysosomal pH and caused a lower density of the lysosomal population upon centrifugation in a Percoll density gradient. No increase in the intralysosomal pH was effected by 3-methyladenine in isolated lysosomes.
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Affiliation(s)
- L H Caro
- Laboratory of Biochemistry, University of Amsterdam, The Netherlands
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Tropea JE, Swank RT, Segal HL. Effect of swainsonine on the processing and turnover of lysosomal beta-galactosidase and beta-glucuronidase from mouse peritoneal macrophages. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)68926-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Taylor ME, Leaning MS, Summerfield JA. Uptake and processing of glycoproteins by rat hepatic mannose receptor. THE AMERICAN JOURNAL OF PHYSIOLOGY 1987; 252:E690-8. [PMID: 3578517 DOI: 10.1152/ajpendo.1987.252.5.e690] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A linear compartmental model has been developed for the in vivo metabolism of glycoproteins. The model is applied to the interpretation of dynamic data from the rat on agalactoorosomucoid (AGOR), an N-acetylglucosamine (GlcNAc-)-terminated glycoprotein, and three neoglycoproteins terminating in mannose [mannose36-bovine serum albumin (Man-BSA)] or glucose [maltose29-BSA (Mal29-BSA) and maltose8-BSA (Mal8-BSA)]. All of these proteins are taken up by the Man/GlcNAc receptor on hepatic sinusoidal cells. The rate of uptake was found to be determined by sugar type (Man-BSA, 0.78 min-1 greater than Mal29-BSA, 0.13 min-1), sugar density (Mal29-BSA greater than Mal8-BSA), and the geometry of the sugar display (AGOR, 0.51 min-1 greater than Mal29-BSA). Intracellular transport from the cell membrane to the lysosomes was slower for Man-BSA (approximately 3 min) than for the other ligands (approximately 0 min), suggesting that receptor-ligand uncoupling was slower for Man-BSA for which the receptor had the highest affinity or that extralysosomal catabolism of the other ligands occurred. Catabolism was also determined by the carbohydrate moiety of the ligand; it was greater for Mal29-BSA and Mal8-BSA (greater than or equal to 0.8 min-1) than for Man-BSA (0.27 min-1), and AGOR, with a complex oligosaccharide, was most resistant to degradation (0.14 min-1). An understanding of these structural features of glycoproteins that influence hepatic uptake, transport, and catabolism will be of value in drug targeting and for enzyme replacement in lysosomal storage disorders.(ABSTRACT TRUNCATED AT 250 WORDS)
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Grimes HD, Watanabe NM, Breidenbach R. Plasma membrane isolated with a defined orientation used to investigate protein topography. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 1986. [DOI: 10.1016/0005-2736(86)90480-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Howard AS, Michael JP. Chapter 3 Simple Indolizidine and Quinolizidine Alkaloids. ACTA ACUST UNITED AC 1986. [DOI: 10.1016/s0099-9598(08)60115-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
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Abstract
Autophagy is defined as any process whereby cellular macromolecules destined for degradation gain access to the lysosomes. A review is presented on the physiological significance, mechanisms and regulation of autophagy in hepatocytes, concentrating on the issue of regulation. The article ends by discussing techniques available for future research.
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Fuhrmann U, Bause E, Ploegh H. Inhibitors of oligosaccharide processing. BIOCHIMICA ET BIOPHYSICA ACTA 1985; 825:95-110. [PMID: 3159432 DOI: 10.1016/0167-4781(85)90095-8] [Citation(s) in RCA: 179] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Kuranda MJ, Aronson NN. Use of active site-directed inhibitors to study in situ degradation of glycoproteins by the perfused rat liver. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(18)89672-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Olden K, Bernard BA, Humphries MJ, Yeo TK, Yeo KT, White SL, Newton SA, Bauer HC, Parent J. Function of glycoprotein glycans. Trends Biochem Sci 1985. [DOI: 10.1016/0968-0004(85)90238-5] [Citation(s) in RCA: 100] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Abstract
Altogether 30 different sugar analogues have been tested in a cell free system from rat liver or, in part, in freshly prepared hepatocytes. It is our aim to find suitable compounds which are able either to interfere with the metabolization of L-fucose, galactose and N-acetylmannosamine or, alternatively, to block the attachment of these sugars to the nascent oligosaccharide chain. 1-Methylfucoside inhibits the fucokinase by a competitive mode (Ki = 1.1 mmol/l). Both the fucokinase and fucose-1-phosphate pyrophosphorylase activity are impaired by Clobenoside, a chloro-containing glucofuranoside (Ki values between 5 to 10 mmol/l). In hepatocytes this inhibition leads to a drastic reduction of fucoprotein biosynthesis and secretion. 1-Methylenegalactose proved to be a promising competitive inhibitor of the galactokinase (Ki = 4.1 mmol/l), while the efficacy of 2-deoxy-2-fluoro-galactose and 6-deoxy-6-fluoro-galactose is less pronounced. Part of these sugar analogues could become a suitable tool in order to elucidate the biological significance of terminal and subterminal sugars.
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Winkler JR, Segal HL. Swainsonine inhibits glycoprotein degradation by isolated rat liver lysosomes. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(17)42558-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Breitfeld PP, Rup D, Schwartz AL. Influence of the N-linked oligosaccharides on the biosynthesis, intracellular routing, and function of the human asialoglycoprotein receptor. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(18)90980-4] [Citation(s) in RCA: 67] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Segal HL, Winkler JR. Mechanism and regulation of protein turnover: effect of the alpha-mannosidase inhibitor, swainsonine, on glycoprotein degradation. CURRENT TOPICS IN CELLULAR REGULATION 1984; 24:229-49. [PMID: 6209068 DOI: 10.1016/b978-0-12-152824-9.50029-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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