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Zhang Q, Higginbotham JN, Jeppesen DK, Yang YP, Li W, McKinley ET, Graves-Deal R, Ping J, Britain CM, Dorsett KA, Hartman CL, Ford DA, Allen RM, Vickers KC, Liu Q, Franklin JL, Bellis SL, Coffey RJ. Transfer of Functional Cargo in Exomeres. Cell Rep 2019; 27:940-954.e6. [PMID: 30956133 PMCID: PMC6559347 DOI: 10.1016/j.celrep.2019.01.009] [Citation(s) in RCA: 240] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 11/02/2018] [Accepted: 01/02/2019] [Indexed: 01/01/2023] Open
Abstract
Exomeres are a recently discovered type of extracellular nanoparticle with no known biological function. Herein, we describe a simple ultracentrifugation-based method for separation of exomeres from exosomes. Exomeres are enriched in Argonaute 1-3 and amyloid precursor protein. We identify distinct functions of exomeres mediated by two of their cargo, the β-galactoside α2,6-sialyltransferase 1 (ST6Gal-I) that α2,6- sialylates N-glycans, and the EGFR ligand, amphiregulin (AREG). Functional ST6Gal-I in exomeres can be transferred to cells, resulting in hypersialylation of recipient cell-surface proteins including β1-integrin. AREG-containing exomeres elicit prolonged EGFR and downstream signaling in recipient cells, modulate EGFR trafficking in normal intestinal organoids, and dramatically enhance the growth of colonic tumor organoids. This study provides a simplified method of exomere isolation and demonstrates that exomeres contain and can transfer functional cargo. These findings underscore the heterogeneity of nanoparticles and should accelerate advances in determining the composition and biological functions of exomeres.
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Affiliation(s)
- Qin Zhang
- Department of Medicine/Gastroenterology and Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - James N Higginbotham
- Department of Medicine/Gastroenterology and Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Dennis K Jeppesen
- Department of Medicine/Gastroenterology and Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Yu-Ping Yang
- Department of Medicine/Gastroenterology and Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Wei Li
- Department of Medicine/Gastroenterology and Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Eliot T McKinley
- Department of Medicine/Gastroenterology and Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Ramona Graves-Deal
- Department of Medicine/Gastroenterology and Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Jie Ping
- Department of Biostatistics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Colleen M Britain
- Cell, Developmental and Integrative Biology (CDIB), School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Kaitlyn A Dorsett
- Cell, Developmental and Integrative Biology (CDIB), School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Celine L Hartman
- Edward A. Doisy Department of Biochemistry and Molecular Biology and Center for Cardiovascular Research, Saint Louis University School of Medicine, St. Louis, MO 63104, USA
| | - David A Ford
- Edward A. Doisy Department of Biochemistry and Molecular Biology and Center for Cardiovascular Research, Saint Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Ryan M Allen
- Department of Cardiology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Kasey C Vickers
- Department of Cardiology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Qi Liu
- Department of Biostatistics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Jeffrey L Franklin
- Department of Medicine/Gastroenterology and Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37235, USA; Department of Veterans Affairs Medical Center, Nashville, Vanderbilt University, TN 37212, USA
| | - Susan L Bellis
- Cell, Developmental and Integrative Biology (CDIB), School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35233, USA.
| | - Robert J Coffey
- Department of Medicine/Gastroenterology and Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37235, USA; Department of Veterans Affairs Medical Center, Nashville, Vanderbilt University, TN 37212, USA.
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2
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Miyagi T, Kikuchi K, Tamura S. Shigeru Tsuiki: a pioneer in the research fields of complex carbohydrates and protein phosphatases. J Biochem 2011; 150:483-90. [PMID: 22039278 DOI: 10.1093/jb/mvr045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Dr Tsuiki made three major contributions during his illustrious career as a biochemist. First, he developed the procedure for mucin isolation from bovine submaxillary glands. His work became the basis for mucin biochemistry. Second, he identified four distinct molecular species of mammalian sialidase. Subsequent studies based on his work led to the discovery that sialidase plays a unique role as an intracellular signalling factor involved in the regulation of a variety of cellular functions. Finally, he established the molecular basis for the diversity of mammalian protein phosphatases through protein purification and molecular cloning. His work prompted the functional studies of protein phosphatases.
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Affiliation(s)
- Taeko Miyagi
- Department of Cancer Glycosylation Research, Institute of Molecular Biomembrane and Glycobiology, Tohoku Pharmaceutical University, Komatsushima, Aoba-ku, Sendai, Japan
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3
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Maksimovic J, Sharp JA, Nicholas KR, Cocks BG, Savin K. Conservation of the ST6Gal I gene and its expression in the mammary gland. Glycobiology 2010; 21:467-81. [PMID: 21098517 DOI: 10.1093/glycob/cwq185] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Milk sialoglycoconjugates can protect the gastrointestinal tract of the suckling neonate by competitively binding to invading pathogens and promoting growth of beneficial flora, and their potential role in postnatal brain development is of particular interest in human infant nutrition. Although the concentration and the distribution of sialoglycoconjugates have been extensively studied in the milk of various species, the investigation of sialyltransferase gene expression in the mammary gland, in the context of lactation, has been limited. The sialyltransferase enzyme ST6Gal I transfers sialic acid from CMP-sialic acid to type 2 (Galβ1,4GlcNAc) free disaccharides or the termini of N- or O-linked oligosaccharides using an α2,6-linkage. Expression of the ST6Gal I gene is primarily regulated at the level of transcription through the use of several cell and development-specific promoters, producing transcripts with divergent 5' untranslated regions (UTR). In the mouse mammary gland, the novel 5'UTR exon (L) appears to be associated with a drastic increase in ST6Gal I gene expression during lactation. We find that rats also possess an exon (L), suggesting conservation of this regulatory mechanism in rodents. In contrast, an exon (L)-containing transcript was not detected in the lactating bovine or human mammary gland. We also observed a trend of increasing ST6Gal I gene expression in the bovine mammary gland, culminating in involution. This is in contrast to species such as mice where the greatest change in ST6Gal I gene expression occurs between pregnancy and lactation, suggesting different roles in rodents vs. other mammals for α2,6-sialylated oligosaccharides present in milk.
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Affiliation(s)
- Jovana Maksimovic
- Centre for Reproduction and Development, Monash Institute of Medical Research, Clayton 3168, Australia.
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4
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Shimura N, Sogawa Y, Kawakita Y, Ikekita M, Yamazaki N, Kojima S. Radioiodination of glycoprotein-conjugated liposomes by using the Bolton-Hunter reagent and biodistribution in tumor-bearing mice. Nucl Med Biol 2002; 29:491-6. [PMID: 12031885 DOI: 10.1016/s0969-8051(02)00297-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We have developed a suitable radiolabeling method for our new type of glycoprotein-liposome conjugate (GCL), in order to investigate its potential utility as a drug carrier that can target the cellular functions of carbohydrate-binding proteins. In order to obtain radiolabeled GCL with high labeling efficiency, we introduced p-hydroxyphenylpropyl groups into the liposome membrane through the amine moiety of a constitutive phospholipid, dipalmitoylphosphatidylethanolamine (DPPE) by using Bolton-Hunter reagent (BHR). Radioiodination of the introduced tyrosyl groups was performed by the Chloramine-T method. The labeling efficiency of the BHR-treated liposome conjugate was high in comparison with that of the BHR-untreated liposome conjugate. An in vitro inhibition study showed that the binding affinity of 125I-labeled BHR-treated GCL (125I-F3S-BH) with lectin was twice as high as that of untreated conjugate (125I-F3S). The biodistribution of 125I-F3S-BH in mice was considerably different from that of 125I-F3S. 125I-F3S-BH was more rapidly taken up by the liver and was more rapidly excreted from the liver than 125I-F3S. Moreover, 125I-F3S-BH accumulated more rapidly into the kidneys, which resulted a lower radioactivity in the blood circulation at an earlier time point than in the case of 125I-F3S. The characteristics of tumor accumulation of 125I-F3S-BH and 125I-F3S were similar to those in blood. If F3S is to be employed as an in vivo targeting ligand in biodistribution studies, BHR would be a suitable tool for radiolabeling because it allows GCL to retain the biological activity and characteristics of the unmodified conjugate.
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Affiliation(s)
- N Shimura
- Faculty of Pharmaceutical Sciences, Science University of Tokyo, Tokyo, Japan
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5
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Abstract
Protein glycosylation, which is a key post-translational event, is catalysed by the glycosyltransferase family of enzymes. There is an increasing body of evidence to suggest that these enzymes may themselves be glycosylated, possibly as an autocatalytic event. Using a novel in vitro system, we have investigated the role of enzyme glycosylation in sialyltransferase catalytic activity. The enzyme activity is glycosylation dependent, with the penultimate galactose residue on complex N-linked oligosaccharides playing a pivotal role. These results serve to underline the complexity of the glycosylation process.
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Affiliation(s)
- Kieran C Breen
- Department of Psychiatry, University of Dundee, Ninewells Hospital Medical School, Dundee, UK.
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6
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Williams MA, Kitagawa H, Datta AK, Paulson JC, Jamieson JC. Large-scale expression of recombinant sialyltransferases and comparison of their kinetic properties with native enzymes. Glycoconj J 1995; 12:755-61. [PMID: 8748151 DOI: 10.1007/bf00731235] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Values of Km were determined for three purified sialyltransferases and the corresponding recombinant enzymes. The enzymes were Gal beta 1-4GlcNAc alpha 2-6 sialyltransferase and Gal beta 1-3(4)GlcNAc alpha 2-3 sialyltransferase from rat liver; these enzymes are responsible for the attachment of sialic acid to N-linked oligosaccharide chains; and the Gal beta 1-3GalNAc alpha 2-3 sialyltransferase from porcine submaxillary gland that is responsible for the attachment of sialic acid to O-linked glycoproteins and glycolipids. A procedure for the large scale expression of active sialyltransferases from recombinant baculovirus-infected insect cells is described. For the liver enzymes values of Km were determined using rat and human asialo alpha 1 acid glycoprotein and N-acetyllactosamine as variable substrates; lacto-N-tetraose was also used with the Gal beta 1-3(4)GlcNAc alpha 2-3 sialyltransferases. Antifreeze glycoprotein was used as the macromolecular acceptor for the porcine enzyme. Values for Km were also determined using CMP-NeuAc as the variable substrate.
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Affiliation(s)
- M A Williams
- Cytel Corporation, San Diego, California 92121, USA
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7
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Miyagi T, Sato K, Hata K, Taniguchi S. Metastatic potential of transformed rat 3Y1 cell lines is inversely correlated with lysosomal-type sialidase activity. FEBS Lett 1994; 349:255-9. [PMID: 8050577 DOI: 10.1016/0014-5793(94)00682-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We have investigated sialidase activities in transformed rat 3Y1 cells of different metastatic potential. Only lysosome-type sialidase was apparent in the particulate fractions of 3Y1 cells and their transformants. As compared with control 3Y1 cells, src-transformed cells exhibited decreased sialidase activity, and v-fos transfer to these latter induced even more severe decrease in the sialidase activity with acquisition of high lung metastatic ability. Various lysosomal enzymes other than sialidase were hardly affected by the transformation. Sialic acid transfer to N-linked glycoproteins was slightly elevated in the transformants, but not in parallel with their metastatic potential.
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Affiliation(s)
- T Miyagi
- Division of Biochemistry, Miyagi Cancer Center, Japan
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8
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Novel purification of the catalytic domain of Golgi alpha-mannosidase II. Characterization and comparison with the intact enzyme. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)55384-9] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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9
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Sticher U, Gross HJ, Brossmer R. Purification and characterization of alpha (2-6)-sialyltransferase from human liver. Glycoconj J 1991; 8:45-54. [PMID: 1823612 DOI: 10.1007/bf00731642] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A Gal beta 1-4GlcNAc alpha (2-6)-sialyltransferase from human liver was purified 34,340-fold with 18% yield by dye chromatography on Cibacron Blue F3GA and cation exchange FPLC. The enzyme preparation was free of other sialyltransferases. It did not contain CMP-NeuAc hydrolase, protease, or sialidase activity, and was stable at -20 degrees C for at least eight months. The donor substrate specificity was examined with CMP-NeuAc analogues modified at C-5 or C-9 of the N-acetylneuraminic acid moiety. Affinity of the human enzyme for parent CMP-NeuAc and each CMP-NeuAc analogue was substantially higher than the corresponding Gal beta 1-4GlcNAc alpha (2-6)-sialyltransferase from rat liver.
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Affiliation(s)
- U Sticher
- Institut für Biochemie II, Universität Heidelberg, FRG
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10
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Broquet P, Baubichon-Cortay H, George P, Louisot P. Glycoprotein sialyltransferases in eucaryotic cells. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1991; 23:385-9. [PMID: 2015947 DOI: 10.1016/0020-711x(91)90164-i] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- P Broquet
- INSERM U.189, Faculté de Médecine Lyon-Sud, Oullins, France
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11
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Miyagi T, Sagawa J, Kuroki T, Matsuya Y, Tsuiki S. Tumor-promoting phorbol ester induces alterations of sialidase and sialyltransferase activities of JB6 cells. Jpn J Cancer Res 1990; 81:1286-92. [PMID: 2125997 PMCID: PMC5918020 DOI: 10.1111/j.1349-7006.1990.tb02692.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Sialidase and sialyltransferase activities were studied in JB6 mouse epidermal cells before and after exposure to phorbol ester, 12-O-tetradecanoyl phorbol-13-acetate (TPA), which irreversibly induces anchorage-independent growth and tumorigenicity. JB6 cells exhibited sialidase activities toward 4-methylumbelliferyl-alpha-D-N-acetylneuraminic acid (4MU-NeuAc) and gangliosides at pH 4.5 in the particulate fraction but apparently not in the cytosol at pH 4.5 or 6.0. In JB6 cells exposed to TPA and in the anchorage-independent transformants, the sialidase activity toward 4MU-NeuAc was decreased and the activity toward gangliosides was increased compared with those in untreated JB6 cells. Immunological analysis with antisera against membrane-associated sialidases I and II revealed that plasma membrane-associated sialidase I was increased and lysosomal membrane-associated sialidase II was decreased under these conditions. TPA treatment also affected the sialyltransferase activities of JB6 cells: and elevation of the transfer activities toward asialo-orosomucoid and asialo-porcine submaxillary mucin but a reduction of GM3 and GD3 synthase activities were observed on exposure to TPA and in cells transformed by TPA to retain anchorage-independency. These results suggest that an increase in sialic acid bound to glycoproteins and a decrease in that bound to glycolipids may occur in JB6 cells exposed to TPA and in the anchorage-independent transformants.
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Affiliation(s)
- T Miyagi
- Laboratory of Biochemistry, Tohoku University, Sendai
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12
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Abstract
The cell surface is involved in cell growth and division, cell-cell interaction, communication, differentiation and migration, and other processes likely to be involved in malignant transformation and/or the metastatic spread of cancer. Although there are many alterations of glycoproteins and glycolipids on the malignant cell surface, it is unclear whether these alterations are epiphenomena or an integral part of the malignancy process. This article reviews the recent literature and some earlier studies relevant for understanding emerging concepts and trends with respect to malignant cell glycoconjugates. Emphasis is on structural alterations of the carbohydrate portions of malignant cell glycoproteins and glycolipids and on the enzymes (glycosyltransferases and glycosidases) involved in their metabolism. Practical applications derived from malignant cell glycoconjugate studies are discussed briefly with respect to the diagnosis, staging, monitoring, and treatment of malignant disease. The review concludes by indicating which research areas on malignant cell glycoconjugates are likely to be fruitful in increasing our basic understanding of, and ability to deal effectively with, malignant disease.
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Affiliation(s)
- J A Alhadeff
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania
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13
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Miyagi T, Koseki M, Tsuiki S. Comparative study of the levels of sialyltransferases responsible for the formation of sugar chains in glycoproteins and gangliosides in rat liver and hepatomas. Jpn J Cancer Res 1988; 79:742-9. [PMID: 3137201 PMCID: PMC5917584 DOI: 10.1111/j.1349-7006.1988.tb02231.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Sialyltransferases responsible for the formation of sugar chains in glycoproteins were studied in rat hepatoma in comparison with rat liver. Hepatoma induced by feeding Wistar rats with 3'-methyl-4-dimethylaminoazobenzene (MeDAB) was more active than Wistar liver in sialylating asialo-orosomucoid, and this was due to an increased activity of Gal(beta 1----4)GlcNAc (alpha 2----6) sialyltransferase, the major sialyltransferase in these tissues. Gal(beta 1----3,4)GlcNAc (alpha 2----3) sialyltransferase and the sialyltransferase acting on asialo-bovine submaxillary mucin were, however, decreased in the hepatoma. A similar pattern of sialyltransferase alterations was observed in regenerating liver and other tumors such as AH-109A hepatoma and Sato lung cancer, both of which had been inoculated into Donryu rats. In contrast to these sialyltransferases, the activities of the sialyltransferases responsible for the formation of gangliosides were markedly different even between Wistar and Donryu livers. When compared with Wistar liver, MeDAB-induced hepatoma was higher in lactosylceramide- and lower in GM3-sialyltransferase activity, but these two activities were both lower in AH-109A compared with Donryu liver.
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Affiliation(s)
- T Miyagi
- Research Institute for Tuberculosis and Cancer, Tohoku University, Sendai
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Imai Y, Yamashita Y, Osawa T. Enhancement of the activities of glycosyltransferases involved in the biosynthesis of mucin-type sugar chains in autoimmune MRL lpr/lpr mouse T cells. Mol Immunol 1988; 25:419-28. [PMID: 3137457 DOI: 10.1016/0161-5890(88)90161-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Lymph node (LN) T cells from autoimmune MRL/MpJ-lpr/lpr (lpr) mice and control MRL/MpJ-+/+ (+/+) mice were compared as to their cell surface lectin-binding sites and glycosyltransferase activities. T cells from enlarged LN of lpr mice expressed a higher amount of binding sites for lectins reactive to mucin-type sugar chains than normal +/+ mouse T cells. Correspondingly, glycosyltransferase activities involved in the biosynthesis of mucin-type sugar chains were higher in lpr mouse T cells than in +/+ T cells. The activities of UDP-N-acetylgalactosamine (GalNAc):polypeptide GalNAc transferase and UDP-galactose (Gal):asialo bovine submaxillary mucin (BSM) Gal transferase were found to be elevated. The activity of UDP-Gal:asialo-agalacto transferrin Gal transferase, which is involved in the biosynthesis of complex type sugar chains, was also increased in lpr mice but to a smaller extent than the mucin-type Gal transferase activities. An abnormality in sialyltransferase activity was also found in lpr T cells.
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Affiliation(s)
- Y Imai
- Division of Chemical Toxicology and Immunochemistry, Faculty of Pharmaceutical Sciences, University of Tokyo, Japan
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15
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Abstract
Using the particulate fraction of tissue homogenate, plasma membrane-associated sialidase was assayed at pH 4.5 with bovine brain mixed gangliosides as the substrate. The activity was lower in rat hepatoma induced by 3'-methyl-4-dimethylaminoazobenzene (MeDAB) and transplantable AH-109A rat hepatoma than in normal rat liver. The enzyme was almost quantitatively solubilized from liver particulate fraction by using 0.5% (w/v) sodium deoxycholate plus 0.2% (w/v) Triton X-100. When chromatographed on DEAE-cellulose, the solubilized activity emerged as a single peak. The enzyme thus obtained was maximally active at pH 4.5, and readily hydrolyzed mixed gangliosides but was less active toward 4-methylumbelliferyl-alpha-N-acetylneuraminic acid, 3'-sialyllactose and fetuin. The corresponding enzyme from MeDAB-induced hepatoma was indistinguishable from the liver enzyme in terms of ease of solubilization, pH-activity relationship, chromatographic behavior and substrate preference. It therefore appears that the plasma membrane-associated sialidase of hepatomas differs from that of liver only in the tissue level of activity.
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Affiliation(s)
- J Sagawa
- Biochemistry Laboratory, Tohoku University
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16
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Primary structure of beta-galactoside alpha 2,6-sialyltransferase. Conversion of membrane-bound enzyme to soluble forms by cleavage of the NH2-terminal signal anchor. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)45441-5] [Citation(s) in RCA: 308] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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17
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Miyagi T, Tsuiki S. Evidence for sialidase hydrolyzing gangliosides GM2 and GM1 in rat liver plasma membrane. FEBS Lett 1986; 206:223-8. [PMID: 3758350 DOI: 10.1016/0014-5793(86)80985-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Rat liver plasma membrane removed sialic acid from mixed bovine brain gangliosides more efficiently than from sialyllactose and orosomucoid with an optimal pH of 4.5. When individual gangliosides, each labeled with [14C]sialic acid or [3H]sphingosine, were tested, not only GD1a and GM3 but also GM2 and GM1, both of which had been considered to resist mammalian sialidases, were desialylated. The products of GM2 and GM1 hydrolysis were identified as asialo-GM2 and asialo-GM1, respectively, by thin-layer chromatography.
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19
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Purification of bovine colostrumβ-galactosideα(2–6)sialyltransferase to near homogeneity by affinity chromatography. Glycoconj J 1984. [DOI: 10.1007/bf01213727] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Miyagi T, Tsuiki S. Rat-liver lysosomal sialidase. Solubilization, substrate specificity and comparison with the cytosolic sialidase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1984; 141:75-81. [PMID: 6723666 DOI: 10.1111/j.1432-1033.1984.tb08159.x] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Purified liver lysosomes, prepared from rats previously injected with Triton WR-1339, exhibited sialidase activity towards sialyllactose, fetuin, submaxillary mucin (bovine) and gangliosides, and could be disrupted hypotonically with little loss in these activities. After centrifugation, the activities with sialyllactose and fetuin were largely recovered in the supernatant, demonstrating that they were originally in the intralysosomal space. The activities towards submaxillary mucin and gangliosides, on the other hand, remained in the pellet. In the supernatant, activity with fetuin or orosomucoid was markedly reduced by protease inhibitors, suggesting that proteolysis of these glycoproteins may be prerequisite to sialidase activity. The intralysosomal sialidase was solubilized from the mitochondrial-lysosomal fraction of rat liver and partially purified by Sephadex G-200, or Sephadex G-200 followed by CM-cellulose. The enzyme was maximally active at pH 4.7 with sialyllactose as substrate and had a minimum relative molecular mass of 60 000 +/- 5000 by gel filtration; it hydrolyzed a variety of sialooligosaccharides , those containing (alpha 2----3)sialyl linkages being better substrates than those with (alpha 2----6)sialyl linkages. The enzyme failed to attack submaxillary mucin and gangliosides. It was also inactive towards fetuin, orosomucoid and transferrin but capable of hydrolyzing glycopeptides from pronase digest of fetuin. In contrast to the intralysosomal sialidase, the sialidase partially purified from rat liver cytosol by (NH4)2SO4 fractionation followed by chromatography on DEAE-cellulose and CM-cellulose hydrolyzed fetuin and orosomucoid to the extent about half that for sialyllactose. The enzyme was maximally active at pH 5.8 and had a relative molecular mass of approximately 60 000. It also hydrolyzed gangliosides but not submaxillary mucin.
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