The Experts below are selected from a list of 2358 Experts worldwide ranked by ideXlab platform
Sen-itiroh Hakomori - One of the best experts on this subject based on the ideXlab platform.
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Synthetic carbohydrate vaccines: Synthesis and immunogenicity of Tn Antigen conjugates
Bioorganic & Medicinal Chemistry, 1994Co-Authors: Tatsushi Toyokuni, Sen-itiroh Hakomori, Anil K. SinghalAbstract:A tumor-associated carbohydrate Antigen, Tn Antigen (GalNAc alpha 1-->O-Ser), was synthesized with a spacer arm, and assembled to dimeric and trimeric structures using N-tert-butyloxycarbonyl-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-alpha- D-galactopyranosyl)-L-serine as a key building block. The synthetic Antigens were conjugated with OSA and their immunogenicity examined in mice. Mice immunized with dimeric or trimeric Tn Antigen showed a stronger antibody (IgM) response to a Tn-glycoprotein (asialo-ovine submaxillary mucin) than mice immunized with monomeric Tn Antigen. The dimeric and trimeric Tn Antigens also induced measurable IgG responses. The dimeric Tn Antigen was further coupled to a Starburst dendrimer (5th generation) and to tripalmitoyl-S-glycerylcysteinyl-serine, a synthetic lipopeptide of the active moiety of a major lipoprotein of Escherichia coli. Unexpectedly, the Starburst dendrimer conjugate did not stimulate any immune response specific to Tn Antigen. On the other hand, immunization of mice with the lipopeptide conjugate produced not only a high IgM response but also significant IgG anti-Tn response without any carrier molecules or additional adjuvants. The production of IgG antibody is quite significant since carbohydrate Antigens are in general known to produce only IgM antibody response. Being a totally synthetic, low-molecular weight, and carrier-free immunogen, the lipopeptide conjugate could be a prototype of synthetic carbohydrate vaccines.
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induction of alpha n acetylgalactosamine o serine threonine Tn Antigen mediated cellular immune response for active immunotherapy in mice
Cancer Research, 1991Co-Authors: Anil K. Singhal, Melinda Fohn, Sen-itiroh HakomoriAbstract:Abstract A block in carbohydrate chain elongation of O -glycosylated mucins results in accumulation of α-GalNAc O linked to serine or threonine (Tn Antigen) in a large percentage of human adenocarcinomas. Immunization of mice with desialylated ovine submaxillary mucin (A-OSM), which contains a large concentration of Tn Antigen, provided protection against challenge of a highly invasive Tn expressing syngeneic mouse mammary tumor, TA3-Ha. A similar protective effect was not observed in mice immunized with the deglycosylated mucin or irridiated TA3-Ha cells. Immunization with A-OSM but not with deglycosylated mucin resulted in high anti-Tn antibody response in mice. A-OSM induced in vitro proliferation of T-lymphocytes obtained from mice preimmunized with A-OSM or irradiated TA3-Ha cells. This Antigen-specific T-cell response was significantly lower if lymphocytes were stimulated with either the deglycosylated or sialylated form of mucin. A-OSM stimulation induced primarily a CD4 + T-cell population, and these cells secreted interleukin 2 in a dose-dependent fashion. A-OSM was also able to induce delayedtype hypersensitivity in mice in response to footpad injections with irradiated TA3-Ha cells. These studies indicate that Tn Antigen presented on a protein backbone is capable of providing cellular immunity and protection against tumor in mice.
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Induction of alpha-N-acetylgalactosamine-O-serine/threonine (Tn) Antigen-mediated cellular immune response for active immunotherapy in mice.
Cancer research, 1991Co-Authors: Anil K. Singhal, Melinda Fohn, Sen-itiroh HakomoriAbstract:Abstract A block in carbohydrate chain elongation of O -glycosylated mucins results in accumulation of α-GalNAc O linked to serine or threonine (Tn Antigen) in a large percentage of human adenocarcinomas. Immunization of mice with desialylated ovine submaxillary mucin (A-OSM), which contains a large concentration of Tn Antigen, provided protection against challenge of a highly invasive Tn expressing syngeneic mouse mammary tumor, TA3-Ha. A similar protective effect was not observed in mice immunized with the deglycosylated mucin or irridiated TA3-Ha cells. Immunization with A-OSM but not with deglycosylated mucin resulted in high anti-Tn antibody response in mice. A-OSM induced in vitro proliferation of T-lymphocytes obtained from mice preimmunized with A-OSM or irradiated TA3-Ha cells. This Antigen-specific T-cell response was significantly lower if lymphocytes were stimulated with either the deglycosylated or sialylated form of mucin. A-OSM stimulation induced primarily a CD4 + T-cell population, and these cells secreted interleukin 2 in a dose-dependent fashion. A-OSM was also able to induce delayedtype hypersensitivity in mice in response to footpad injections with irradiated TA3-Ha cells. These studies indicate that Tn Antigen presented on a protein backbone is capable of providing cellular immunity and protection against tumor in mice.
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Synthetic vaccines: I. Synthesis of multivalent Tn Antigen cluster-lysyllysine conjugates
Tetrahedron Letters, 1990Co-Authors: Tatsushi Toyokuni, Barbara Dean, Sen-itiroh HakomoriAbstract:Monomer, dimer, and trimer of Tn Antigen (GalNAcα1→O-Ser) were coupled to L-lysyllysine to construct multivalent and clustering structures of Tn Antigen. The method has made it possible to provide pertinent carbohydrate Antigens for the development of synthetic vaccines against tumors.
Anil K. Singhal - One of the best experts on this subject based on the ideXlab platform.
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Synthetic carbohydrate vaccines: Synthesis and immunogenicity of Tn Antigen conjugates
Bioorganic & Medicinal Chemistry, 1994Co-Authors: Tatsushi Toyokuni, Sen-itiroh Hakomori, Anil K. SinghalAbstract:A tumor-associated carbohydrate Antigen, Tn Antigen (GalNAc alpha 1-->O-Ser), was synthesized with a spacer arm, and assembled to dimeric and trimeric structures using N-tert-butyloxycarbonyl-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-alpha- D-galactopyranosyl)-L-serine as a key building block. The synthetic Antigens were conjugated with OSA and their immunogenicity examined in mice. Mice immunized with dimeric or trimeric Tn Antigen showed a stronger antibody (IgM) response to a Tn-glycoprotein (asialo-ovine submaxillary mucin) than mice immunized with monomeric Tn Antigen. The dimeric and trimeric Tn Antigens also induced measurable IgG responses. The dimeric Tn Antigen was further coupled to a Starburst dendrimer (5th generation) and to tripalmitoyl-S-glycerylcysteinyl-serine, a synthetic lipopeptide of the active moiety of a major lipoprotein of Escherichia coli. Unexpectedly, the Starburst dendrimer conjugate did not stimulate any immune response specific to Tn Antigen. On the other hand, immunization of mice with the lipopeptide conjugate produced not only a high IgM response but also significant IgG anti-Tn response without any carrier molecules or additional adjuvants. The production of IgG antibody is quite significant since carbohydrate Antigens are in general known to produce only IgM antibody response. Being a totally synthetic, low-molecular weight, and carrier-free immunogen, the lipopeptide conjugate could be a prototype of synthetic carbohydrate vaccines.
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induction of alpha n acetylgalactosamine o serine threonine Tn Antigen mediated cellular immune response for active immunotherapy in mice
Cancer Research, 1991Co-Authors: Anil K. Singhal, Melinda Fohn, Sen-itiroh HakomoriAbstract:Abstract A block in carbohydrate chain elongation of O -glycosylated mucins results in accumulation of α-GalNAc O linked to serine or threonine (Tn Antigen) in a large percentage of human adenocarcinomas. Immunization of mice with desialylated ovine submaxillary mucin (A-OSM), which contains a large concentration of Tn Antigen, provided protection against challenge of a highly invasive Tn expressing syngeneic mouse mammary tumor, TA3-Ha. A similar protective effect was not observed in mice immunized with the deglycosylated mucin or irridiated TA3-Ha cells. Immunization with A-OSM but not with deglycosylated mucin resulted in high anti-Tn antibody response in mice. A-OSM induced in vitro proliferation of T-lymphocytes obtained from mice preimmunized with A-OSM or irradiated TA3-Ha cells. This Antigen-specific T-cell response was significantly lower if lymphocytes were stimulated with either the deglycosylated or sialylated form of mucin. A-OSM stimulation induced primarily a CD4 + T-cell population, and these cells secreted interleukin 2 in a dose-dependent fashion. A-OSM was also able to induce delayedtype hypersensitivity in mice in response to footpad injections with irradiated TA3-Ha cells. These studies indicate that Tn Antigen presented on a protein backbone is capable of providing cellular immunity and protection against tumor in mice.
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Induction of alpha-N-acetylgalactosamine-O-serine/threonine (Tn) Antigen-mediated cellular immune response for active immunotherapy in mice.
Cancer research, 1991Co-Authors: Anil K. Singhal, Melinda Fohn, Sen-itiroh HakomoriAbstract:Abstract A block in carbohydrate chain elongation of O -glycosylated mucins results in accumulation of α-GalNAc O linked to serine or threonine (Tn Antigen) in a large percentage of human adenocarcinomas. Immunization of mice with desialylated ovine submaxillary mucin (A-OSM), which contains a large concentration of Tn Antigen, provided protection against challenge of a highly invasive Tn expressing syngeneic mouse mammary tumor, TA3-Ha. A similar protective effect was not observed in mice immunized with the deglycosylated mucin or irridiated TA3-Ha cells. Immunization with A-OSM but not with deglycosylated mucin resulted in high anti-Tn antibody response in mice. A-OSM induced in vitro proliferation of T-lymphocytes obtained from mice preimmunized with A-OSM or irradiated TA3-Ha cells. This Antigen-specific T-cell response was significantly lower if lymphocytes were stimulated with either the deglycosylated or sialylated form of mucin. A-OSM stimulation induced primarily a CD4 + T-cell population, and these cells secreted interleukin 2 in a dose-dependent fashion. A-OSM was also able to induce delayedtype hypersensitivity in mice in response to footpad injections with irradiated TA3-Ha cells. These studies indicate that Tn Antigen presented on a protein backbone is capable of providing cellular immunity and protection against tumor in mice.
Ikuo Yamashina - One of the best experts on this subject based on the ideXlab platform.
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Developmental expression of a unique carbohydrate Antigen, Tn Antigen, in mouse central nervous tissues
Journal of Neuroscience Research, 2001Co-Authors: Kaoru Akita, Mizue Inoue, Ikuo Yamashina, Shinji Fushiki, Takahiro Fujimoto, Kayoko Oguri, Minoru Okayama, Hiroshi NakadaAbstract:Using an anti-Tn monoclonal antibody, the Tn Antigen was detected immunohistochemically in prenatal and early posTnatal central nervous tissues. On embryonic day 9 (E9), the Antigen was distributed throughout the single neuroepithelial layer in the neocortex and then became more prominent in the preplate than in the ventricular zone along with formation of the preplate. Following division of the preplate and concomitant formation of the cortical plate, distinct labeling of the neocortex occurred in the marginal, subplate and intermediate zones, whereas in the cortical plate and ventricular zone were virtually not immunostained. It is notable that thalamocortical afferent fibers were also immunostained specifically on E14. After birth, the localization of the Antigen became less noticeable and by 3 weeks after birth, the Antigen had substantially disappeared. In the developing cerebellum, prominent labeling was also observed in the molecular layer and outskirts of the cerebellar nuclei on early posTnatal days. To characterize the glycoprotein bearing the Tn Antigen biochemically, immunoblot analysis was performed. The glycoprotein, most of which was extracted with a salt solution, migrated as a broad smeared band corresponding to a molecular weight of about 250 kDa on SDS-PAGE. Among the various tissues examined, this glycoprotein was only detected in the brain and its amount increased until an early posTnatal stage with a peak on posTnatal day 3 (P3), and then decreased gradually with age. This spatially and developmentally regulated expression of the Tn Antigen suggests that this Antigen plays a significant role in brain development. J. Neurosci. Res. 65:595–603, 2001. © 2001 Wiley-Liss, Inc.
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Identification of the core protein carrying the Tn Antigen in mouse brain: specific expression on syndecan-3.
Cell Structure and Function, 2001Co-Authors: Kaoru Akita, Mizue Inoue, Ikuo Yamashina, Shinji Fushiki, Takahiro Fujimoto, Seiichi Munesue, Kayoko Oguri, Minoru Okayama, Hiroshi NakadaAbstract:We isolated glycoproteins carrying the Tn Antigen, which was expressed spatiotemporally in the developing mouse brain. The Tn Antigen was expressed on two molecular species with a molecular weight from 200 to 350 kDa and 110 to 160 kDa, as judged on SDS-PAGE. Although the two glycoproteins showed different susceptibilities to heparitinase I and solubilities in a salt solution, after treatment with V8 protease they showed the same mobility corresponding to a molecular weight of 90 kDa on SDS-PAGE, suggesting that these two molecules shared a common core protein. Partial N-terminal sequences of the glycoproteins were determined, i.e. AQRXRNENFERPV and ALAAPXAPAMLP, which were identified as the sequences of the N-terminal and central portions of syndecan-3, respectively. Both glycoproteins were reactive to anti-mouse syndecan-3 antibody. These results suggest that one is a soluble syndecan-3 cleaved between mucin-like domain and transmembrane domain, and the other is a membrane-bound syndecan-3 lacking N-terminal glycosaminoglycan attachment sites, and that both glycoproteins have a mucin-like domain characteristic of syndecan-3, in which the Tn Antigen may be expressed.
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Distribution of Tn Antigen recognized by an anti-Tn monoclonal antibody (MLS128) in normal and malignant tissues of the digestive tract
Journal of Cancer Research and Clinical Oncology, 1995Co-Authors: Gakuji Ohshio, Hiroshi Nakada, Harumi Sakahara, Hirohiko Yamabe, Masayuki Imamura, Takashi Imamura, Ikuo YamashinaAbstract:Alterations in the normal glycosylation process are often associated with oncogenic transformation. Using an anti-Tn monoclonal antibody, MLS128, we have investigated the immunohistochemical localization of Tn Antigen in normal and malignant tissues of the digestive tract. In normal tissues, MLS128 was immunoreactive with the squamous epithelium of the esophagus and was weakly reactive with the columnar epithelia of the stomach, duodenum, colon, bile duct and pancreatic duct. In malignant, tissues, positive immunostaining was detected with high frequency (75%–100%) in carcinomas of the esophagus, stomach colon, biliary tract and pancreas, whereas 2 of 11 (18%) hepatocellular carcinomas were positive. Tn Antigen was detected in the upper two-thirds of the normal squamous epithelium, and was often detected in squamous cell carcinomas with cancer pearls (keratinization). These results suggest that the expression of Tn Antigen is related to the differentiation of squamous epithelium, or to keratinization. In normal columnar epithelial cells, Tn Antigen was localized mainly to the Golgi area. This intracellular localization was preserved in well-differentiated papillary adenocarcinomas of the colon, but was lost in most cases of tubular adenocarcinomas.
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Expression of sialosyl-Tn Antigen (monoclonal antibody MLS102 reactive) in normal tissues and malignant tumors of the digestive tract
Journal of Cancer Research and Clinical Oncology, 1994Co-Authors: Gakuji Ohshio, Hiroshi Nakada, Mizue Inoue, Nobuhiro Tanaka, Hideyuki Yoshioka, Tadao Manabe, Harumi Sakahara, Hirohiko Yamabe, Masayuki Imamura, Ikuo YamashinaAbstract:Oncogenic transformation is often associated with changes in the glycosylation state of malignant cells. We investigated the immunohistochemical localization of sialosyl-Tn Antigen [O-linked NeuAc(α2→6)GAINAc] using a novel monoclonal antibody MLS102 in normal and malignant digestive-tract tissues. In normal tissues, weak MLS102 immunoreactivity was observed in the epithelium of the esophagus, stomach and colon. However, MLS102 immunoreactivity was strong in the goblet cells of the duodenum, but not in the Brunner glands. In carcinomas of the esophagus, stomach, colon, pancreas and biliary tract, positive staining was detected with a high frequency (80%–100%). In mucinous carcinomas and signet-ring cell carcinomas, malignant cells themselves and the mucins they secreted were strongly positive for sialosyl-Tn Antigen. There was no significant correlation between the frequency of expression of sialosyl-Tn Antigen and the degree of differentiation (grade). However, in the case of well-differentiated adenocarcinomas, sialosyl-Tn Antigen was found mainly in the supranuclear areas (Golgi area), on the apical surface and in the adjacent cytoplasm. In poorly differentiated adenocarcinomas, the Antigen was often detected in the whole plasma membrane and cytoplasm. Therefore, monoclonal antibody MLS102 may be useful in further elucidating the characteristics of digestivetract cancers, and possibly in their treatment.
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Tn Antigen Is Expressed on Leukosialin from T-Lymphoid Cells
Cancer research, 1994Co-Authors: Mizue Inoue, Hiroshi Nakada, Nobuhiro Tanaka, Ikuo YamashinaAbstract:Various T-lymphoid cells were labeled with [3H] glucosamine and then cell lysates were prepared from them. The Tn Antigen was immunoprecipitated and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by fluorography. The Tn Antigen was found to be expressed on leukosialin, a major glycoprotein of T-lymphoid cells. The carbohydrate moieties of leukosialin were isolated from Jurkat and Molt 4 cells by alkaline borohydride treatment. The leukosialin in both cases predominantly contained single N -acetylgalactosamine residues, consistent with expression of the Tn Antigen. Tryptic glycopeptides containing Antigenic sites were isolated using an MLS 128 immunoaffinity column and purified by gel filtration and reverse phase column chromatographies. Sequence analyses revealed that all the glycopeptides obtained contained three consecutive residues of N -acetylgalactosamine-Ser/Thr, supporting the idea that the epitopic structure is a cluster of N -acetylgalactosamineSer/Thr.
Richard D. Cummings - One of the best experts on this subject based on the ideXlab platform.
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The Cosmc connection to the Tn Antigen in cancer.
Disease Markers, 2013Co-Authors: Rajindra P. Aryal, Matthew R. Kudelka, Yingchun Wang, Richard D. CummingsAbstract:Abstract The Tn Antigen is a tumor-associated carbohydrate Antigen that is not normally expressed in peripheral tissues or blood cells. Expression of this Antigen, which is found in a majority of human carcinomas of all types, arises from a blockage in the normal O-glycosylation pathway in which glycans are extended from the common precursor GalNAcα1-O-Ser/Thr (Tn Antigen). This precursor is generated in the Golgi apparatus on newly synthesized glycoproteins by a family of polypeptide α-N-acetylgalactosaminyltransferases (ppGalNAcTs) and then extended to the common core 1 O-glycan Galβ1-3GalNAcα1-O-Ser/Thr (T Antigen) by a single enzyme termed the T-synthase (core 1 β3-galactosyltransferase or C1GalT). Formation of the active form of the T-synthase requires a unique molecular chaperone termed Cosmc, encoded by Cosmc on the X-chromosome (Xq24 in humans, Xc3 in mice). Cosmc resides in the endoplasmic reticulum (ER) and prevents misfolding, aggregation, and proteasome-dependent degradation of newly synthesized T-synthase. Loss of expression of active T-synthase or Cosmc can lead to expression of the Tn Antigen, along with its sialylated version Sialyl Tn Antigen as observed in several cancers. Both genetic and epigenetic pathways, in addition to potential metabolic regulation, can result in abnormal expression of the Tn Antigen. Engineered expression of the Tn Antigen by disruption of either C1GalT (T-syn) or Cosmc in mice is associated with a tremendous range of pathologies and engineered expression of the Tn Antigen in mouse embryos leads to embryonic death. Studies indicate that many membrane glycoproteins expressing the Tn Antigen and/or truncated O-glycans may be dysfunctional, due to degradation and/or misfolding. Thus, expression of normal O-glycans is associated with health and homeostasis whereas truncation of O-glycans, e.g. the Tn and/or Sialyl Tn Antigens is associated with cancer and other pathologies.
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the Tn Antigen structural simplicity and biological complexity
Angewandte Chemie, 2011Co-Authors: Vivianne I. Otto, Richard D. CummingsAbstract:Glycoproteins in animal cells contain a variety of glycan structures that are added co- and/or posttranslationally to proteins. Of over 20 different types of sugar-amino acid linkages known, the two major types are N-glycans (Asn-linked) and O-glycans (Ser/Thr-linked). An abnormal mucin-type O-glycan whose expression is associated with cancer and several human disorders is the Tn Antigen. It has a relatively simple structure composed of N-acetyl-D-galactosamine with a glycosidic α linkage to serine/threonine residues in glycoproteins (GalNAcα1-O-Ser/Thr), and was one of the first glycoconjugates to be chemically synthesized. The Tn Antigen is normally modified by a specific galactosyltransferase (T-synthase) in the Golgi apparatus of cells. Expression of active T-synthase is uniquely dependent on the molecular chaperone Cosmc, which is encoded by a gene on the X chromosome. Expression of the Tn Antigen can arise as a consequence of mutations in the genes for T-synthase or Cosmc, or genes affecting other steps of O-glycosylation pathways. Because of the association of the Tn Antigen with disease, there is much interest in the development of Tn-based vaccines and other therapeutic approaches based on Tn expression.
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The Tn Antigen—Structural Simplicity and Biological Complexity
Angewandte Chemie International Edition, 2011Co-Authors: Vivianne I. Otto, Richard D. CummingsAbstract:Glycoproteins in animal cells contain a variety of glycan structures that are added co- and/or posttranslationally to proteins. Of over 20 different types of sugar-amino acid linkages known, the two major types are N-glycans (Asn-linked) and O-glycans (Ser/Thr-linked). An abnormal mucin-type O-glycan whose expression is associated with cancer and several human disorders is the Tn Antigen. It has a relatively simple structure composed of N-acetyl-D-galactosamine with a glycosidic α linkage to serine/threonine residues in glycoproteins (GalNAcα1-O-Ser/Thr), and was one of the first glycoconjugates to be chemically synthesized. The Tn Antigen is normally modified by a specific galactosyltransferase (T-synthase) in the Golgi apparatus of cells. Expression of active T-synthase is uniquely dependent on the molecular chaperone Cosmc, which is encoded by a gene on the X chromosome. Expression of the Tn Antigen can arise as a consequence of mutations in the genes for T-synthase or Cosmc, or genes affecting other steps of O-glycosylation pathways. Because of the association of the Tn Antigen with disease, there is much interest in the development of Tn-based vaccines and other therapeutic approaches based on Tn expression.
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solid phase synthesis of a pentavalent galnac containing glycopeptide Tn Antigen representing the nephropathy associated iga hinge region
Carbohydrate Research, 2010Co-Authors: Jan G M Bolscher, Richard D. Cummings, Judith Brevoord, Kamran Nazmi, Enno C I Veerman, Joanna A E Van Wijk, Irma Van DieAbstract:Abstract Incomplete or aberrant glycosylation leading to Tn Antigen (GalNAcα1-Ser/Thr) expression on human glycoproteins is strongly associated with human pathological conditions, including tumors, certain autoimmune diseases, such as the idiopathic IgA nephropathy, and may modulate immune homeostasis. In addition, the Tn Antigen is highly expressed by certain pathogens and plays a role in host–pathogen interactions. To enable experimental approaches to study interactions of the Tn Antigen with the immune system and analyze anti-Tn antibody responses in infection or disorders, we generated a Tn-expressing resource that can be used for high-throughput screening. In consideration of IgA nephropathy in which the hinge region is incompletely glycosylated, we used this hinge sequence that encodes five potential glycosylation sites as the ideal template for the synthesis of a Tn Antigen-expressing glycopeptide. Inclusion of an N-terminal biotin in the peptide enabled binding to streptavidin-coated ELISA plates as monitored using Helix pomatia agglutinin or anti-Tn monoclonal antibody. We also found that the biotinylated IgA-Tn peptide is a functional acceptor for β1-3-galactosylation using recombinant T-synthase (β1-3-galactosyltransferase). Besides its immunochemical functionality as a possible diagnostic tool for IgA nephropathy, the peptide is an excellent substrate for glycan elongation and represents a novel template applicable for glycan–Antigen-associated diseases.
Seiji Igarashi - One of the best experts on this subject based on the ideXlab platform.
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expression of vicia villosa agglutinin vva binding glycoprotein in primary breast cancer cells in relation to lymphatic metastasis is atypical muc1 bearing Tn Antigen a receptor of vva
Breast Cancer Research and Treatment, 2006Co-Authors: Takanori Kawaguchi, Hiroshi Takazawa, Shunsuke Imai, Junji Morimoto, Takanori Watanabe, Masahiko Kanno, Seiji IgarashiAbstract:Aberrant carbohydrate expression frequently occurs in breast cancer and may endow cells with metastatic potential. Here we first studied the relationship between expression of Vicia villosa agglutinin (lectin) (VVA)-binding carbohydrates and aggressive breast cancer. We then investigated the molecular characteristics of these glycoproteins and compared them with those of glycoproteins recognized by the mouse anti-Tn monoclonal antibody (MAb) HB-Tn1. Histochemical studies of samples from 322 cases of invasive ductal carcinoma demonstrated that VVA-binding carbohydrate expression correlated with tumor stage, lymphatic invasion, and lymph node metastasis (p=0.0385, p=0.0019, and p=0.0430. respectively). Western blotting analysis of frozen materials from 39 cases, under denaturing and reducing conditions, revealed that the major cancer cell-specific VVA-binding proteins were molecules of about 30, 33, and >200 kDa. Cases expressing the ∼33 kDa molecule had significant lymphatic invasion more frequently than did cases not expressing this molecule (p=0.0076). Binding of VVA to the ∼30 and ∼33 kDa molecules was completely lost by preincubation of VVA with 1 mM Tn Antigen (N-acetylgalactosamine α1- O-serine). The VVA-binding molecules appeared to react with VU-3C6 anti-MUC1 MAb. Expression of HB-Tn1 in breast cancer cells showed significant correlation with expression of VVA-binding carbohydrate(s) (p<0.0001) but HB-Tn1 reactivity was not clearly related to breast cancer aggressiveness. Because anti-Tn MAbs bound to Tn Antigen clusters, we concluded that atypical MUC1 bearing the noncluster form of Tn Antigen is implicated in aggressive growth of primary breast cancer cells, particularly in lymphatic metastasis.
