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- Title
- MULTIVALENT PROTEIN GLYCOSYLATION: A DRIVING FORCE OF CANCER PROGRESSION AND ALZHEIMER’S DISEASE PATHOGENESIS.
- Creator
- Singh, YashoNandini, Cudic, Maré, Florida Atlantic University, Department of Chemistry and Biochemistry, Charles E. Schmidt College of Science
- Abstract/Description
-
Glycosylation is a frequent and heterogeneous post-translational protein modification occurring in all domains of life. Aberrant cell-surface glycosylation is shown to mediate several processes involved in tumor cell proliferation, adhesion, and metastasis. Recent findings linked altered protein glycosylation to Alzheimer’s disease (AD) pathogenesis. One key obstacle in studying functional consequences of glycosylation has been the lack of structurally defined glycopeptide or protein model...
Show moreGlycosylation is a frequent and heterogeneous post-translational protein modification occurring in all domains of life. Aberrant cell-surface glycosylation is shown to mediate several processes involved in tumor cell proliferation, adhesion, and metastasis. Recent findings linked altered protein glycosylation to Alzheimer’s disease (AD) pathogenesis. One key obstacle in studying functional consequences of glycosylation has been the lack of structurally defined glycopeptide or protein model compounds for biochemical studies at the molecular level. For tumor progression, studies are crucial towards understanding the glycan-lectin recognition process tied to deciphering the information contained in glycan structures and for AD, foundational studies are necessary for understanding the role of O-glycosylation in protein processing and its fate toward the amyloid pathway. In chapter 1, a highly O-glycosylated transmembrane and cancer-associated mucin protein, MUC1, is used as a model for designing synthetic tools for exploring its role in metastasis via association with lectins and specificity of anti-MUC1 antibodies. This dissertation for the first time presents a MUC1-based positional scanning synthetic glycopeptide combinatorial library that varies in the number and location of tumor-associated Tn antigen. The importance of defined structural complexity for evaluating glycan density and glycosylation patterns for binding to Tn-specific plant lectins and anti-MUC1 (mouse) monoclonal antibodies was revealed using an enzyme-linked lectin assay (ELLA). Chapter 2 addressed the growing significance of peptide lectinomimics for recognizing tumor-specific glycans. Fluorescently labelled alanine scan analogues of odorranalectin (OL), a cyclic peptide that exhibits lectin like properties, were screened for binding BSA-conjugated monosaccharides using ELLA. Results revealed that Lys5, Phe7, Tyr9, Gly12, Leu14, and Thr17 were crucial for binding BSA-L-fucose, BSA-Dgalactose and BSA-N-acetyl-D-galactosamine. The thermodynamics of binding of the selected alanine analogues was evaluated by isothermal titration calorimetry. The thermodynamic profile of interactions with asialofetuin exhibits shift to an entropy-driven mechanism compared to fucoidan, which displayed an enthalpy-entropy compensation, typically associated with the carbohydrate-lectin recognition process. Chapter 3 focused on amyloid-precursor protein (APP) O-glycosylation and its role in AD pathogenesis. We synthesized native and Swedish-mutated (glyco)peptides with O-GalNAc moiety on Thr663 and/or Ser667 or Tyr681 to explore the role of glycosylation on conformation, secretase activity, and aggregation kinetics of Aβ40. Our results show that conformation is strongly dependent on external conditions such as buffer ions and solvent polarity as well as internal modifications of (glyco)peptides such as length, O-glycosylation, and Swedish mutation (Lys670Asn/Met671Leu). Furthermore, the level of β-secretase activity significantly increased for the glycopeptides containing the Swedish mutation compared to their nonglycosylated and native counterparts. Lastly, glycopeptides impacted the kinetics of Aβ40 aggregation by significantly increasing the lag phase and delaying aggregation onset, however, this effect was less pronounced for its Swedish-mutated counterparts.
Show less - Date Issued
- 2022
- PURL
- http://purl.flvc.org/fau/fd/FA00013949
- Subject Headings
- Glycosylation, Alzheimer Disease, Lectins
- Format
- Document (PDF)
- Title
- Agglutinins from marine macroalgae of the southeastern United States.
- Creator
- Bird, Kimon T., Chiles, Thomas C., Longley, Ross E., Kendrick, A. F., Kinkema, M. D., Harbor Branch Oceanographic Institute
- Date Issued
- 1993
- PURL
- http://purl.flvc.org/FCLA/DT/3333208
- Subject Headings
- Agglutinins, Marine algae, Lectins, Mitogens, Lymphocytes
- Format
- Document (PDF)
