{"id":{"repo_id":"buffalo","oai_identifier":"oai:ubir.buffalo.edu:10477/78635"},"canonical_url":"https://search.dev.ndltd.org/etd/buffalo/oai:ubir.buffalo.edu:10477/78635","repository":{"repo_id":"buffalo","name":"Buffalo","base_url":"https://ubir.buffalo.edu/oai/request"},"display":{"title":"Circulating Sialyltransferases Use Platelet Supplied Sialic Acid to Drive Extrinsic Sialylation","abstract":"Ph.D.","abstract_html":"Ph.D.","abstract_has_math":false,"creators":["Manhardt, Charles"],"institution":"State University of New York at Buffalo","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Lau, Joseph","Roswell Park"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2018,"date_issued":"2018-10-26T02:57:12Z","date_published":"2018-10-26T02:57:12Z","updated_at":"2026-07-27T19:05:14Z","subjects":["cellular biology","molecular biology","cancer sciences"],"languages":["eng"],"rights":["Users of works found in University at Buffalo Institutional Repository (UBIR) are responsible for identifying and contacting the copyright owner for permission to reuse. University at Buffalo Libraries do not manage rights for copyright-protected works and cannot assist with permissions.","Copyright retained by author."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/10477/78635","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Lau, Joseph","Roswell Park"]},{"key":"dc:creator","label":"Author","values":["Manhardt, Charles"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2018-10-26T02:57:12Z","2018","2018-08-10 15:39:01"]},{"key":"dc:publisher","label":"Institution","values":["State University of New York at Buffalo"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation","Text"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["cellular biology","molecular biology","cancer sciences"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Users of works found in University at Buffalo Institutional Repository (UBIR) are responsible for identifying and contacting the copyright owner for permission to reuse. University at Buffalo Libraries do not manage rights for copyright-protected works and cannot assist with permissions.","Copyright retained by author."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/10477/78635"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Ph.D.","There are numerous circulating glycosyltransferases found in blood, but understanding their physiologic contributions has been hampered because functional sources of sugar donor substrates needed to drive extracellular glycosylation have not been identified. Activated platelets secrete a plethora of bioactive molecules including pro- and anti-inflammatory mediators. Cargos of sugar donor substrates required for glycosyltransferase activity have also been reported in platelets. Here, we implemented cell and protein based systems to interrogate platelets for their ability to deliver effectively the sugar donor substrate for extracellular sialyltransferases to function. We report that thrombin-activated platelets, at physiologic concentration and pH, can efficiently and effectively substitute for CMP-sialic acid in extracellular ST6Gal-1-mediated sialylation of target cell surfaces. Recent reports documented that extracellular sialyltransferases can remodel both cell surface and secreted glycans by a process other than the canonical cell-autonomous glycosylation that occurs within the intracellular secretory apparatus. Despite association of the abundance of these extracellular sialyltransferases, particularly ST6Gal-1, with disease states such as cancer and a variety of inflammatory conditions, the prevalence of this extrinsic glycosylation pathway in vivo remains unknown. Here we observed no significant extrinsic sialylation in resting mice, suggesting that extrinsic sialylation is not a constitutive process. However, extrinsic sialylation in the periphery could be triggered by inflammatory challenges, such as exposure to ionizing radiation or to bacterial lipopolysaccharides. Sialic acids from circulating platelets were used in vivo to remodel target cell surfaces. Platelet activation was minimally sufficient to elicit extrinsic sialylation, as demonstrated with the FeCl3 model of mesenteric artery thrombosis. While extracellular ST6Gal-1 supports extrinsic sialylation, other sialyltransferases are present in systemic circulation. We observed in vivo extrinsic sialylation also in animals deficient in ST6Gal-1, demonstrating that extrinsic sialylation is not mediated exclusively by ST6Gal-1. Additionally, we find that serum contains enough activated sugar donors and active sialyltransferases to remodel cell glycans. Serum alone or activated human platelets are sufficient to remodel 2,6 sialyl-linkages on sialidase treated cells. Serum from murine or human sources is also able to restore sialyl-Lewis X structures, likely from a non-traditional pathway. Lastly, we find that a mouse lacking both ST6Gal-1 and CMAH functional proteins is hyper inflammatory after being exposed to endotoxin. This mouse develops exaggerated cell efflux to the lung and septic like symptoms. When pre-treated with recombinant ST6Gal-1 the symptoms are less severe. Together, these observations form an emerging picture of glycans biosynthesized by the canonical cell autonomous glycosylation pathway, but subjected to remodeling by extracellular glycan-modifying enzymes."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Circulating Sialyltransferases Use Platelet Supplied Sialic Acid to Drive Extrinsic Sialylation"]}]}],"canonical_facts":{"dc:contributor":["Lau, Joseph","Roswell Park"],"dc:creator":["Manhardt, Charles"],"dc:date":["2018-10-26T02:57:12Z","2018","2018-08-10 15:39:01"],"dc:description":["Ph.D.","There are numerous circulating glycosyltransferases found in blood, but understanding their physiologic contributions has been hampered because functional sources of sugar donor substrates needed to drive extracellular glycosylation have not been identified. Activated platelets secrete a plethora of bioactive molecules including pro- and anti-inflammatory mediators. Cargos of sugar donor substrates required for glycosyltransferase activity have also been reported in platelets. Here, we implemented cell and protein based systems to interrogate platelets for their ability to deliver effectively the sugar donor substrate for extracellular sialyltransferases to function. We report that thrombin-activated platelets, at physiologic concentration and pH, can efficiently and effectively substitute for CMP-sialic acid in extracellular ST6Gal-1-mediated sialylation of target cell surfaces. Recent reports documented that extracellular sialyltransferases can remodel both cell surface and secreted glycans by a process other than the canonical cell-autonomous glycosylation that occurs within the intracellular secretory apparatus. Despite association of the abundance of these extracellular sialyltransferases, particularly ST6Gal-1, with disease states such as cancer and a variety of inflammatory conditions, the prevalence of this extrinsic glycosylation pathway in vivo remains unknown. Here we observed no significant extrinsic sialylation in resting mice, suggesting that extrinsic sialylation is not a constitutive process. However, extrinsic sialylation in the periphery could be triggered by inflammatory challenges, such as exposure to ionizing radiation or to bacterial lipopolysaccharides. Sialic acids from circulating platelets were used in vivo to remodel target cell surfaces. Platelet activation was minimally sufficient to elicit extrinsic sialylation, as demonstrated with the FeCl3 model of mesenteric artery thrombosis. While extracellular ST6Gal-1 supports extrinsic sialylation, other sialyltransferases are present in systemic circulation. We observed in vivo extrinsic sialylation also in animals deficient in ST6Gal-1, demonstrating that extrinsic sialylation is not mediated exclusively by ST6Gal-1. Additionally, we find that serum contains enough activated sugar donors and active sialyltransferases to remodel cell glycans. Serum alone or activated human platelets are sufficient to remodel 2,6 sialyl-linkages on sialidase treated cells. Serum from murine or human sources is also able to restore sialyl-Lewis X structures, likely from a non-traditional pathway. Lastly, we find that a mouse lacking both ST6Gal-1 and CMAH functional proteins is hyper inflammatory after being exposed to endotoxin. This mouse develops exaggerated cell efflux to the lung and septic like symptoms. When pre-treated with recombinant ST6Gal-1 the symptoms are less severe. Together, these observations form an emerging picture of glycans biosynthesized by the canonical cell autonomous glycosylation pathway, but subjected to remodeling by extracellular glycan-modifying enzymes."],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/10477/78635"],"dc:language":["eng"],"dc:publisher":["State University of New York at Buffalo"],"dc:rights":["Users of works found in University at Buffalo Institutional Repository (UBIR) are responsible for identifying and contacting the copyright owner for permission to reuse. University at Buffalo Libraries do not manage rights for copyright-protected works and cannot assist with permissions.","Copyright retained by author."],"dc:subject":["cellular biology","molecular biology","cancer sciences"],"dc:title":["Circulating Sialyltransferases Use Platelet Supplied Sialic Acid to Drive Extrinsic Sialylation"],"dc:type":["Dissertation","Text"]},"updated_at":"2026-07-27T19:05:14Z"}