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Poirier, Raphael

University of British Columbia

Integrin alpha v beta five (ITGαvβ₅) and milk fat globule epidermal growth factor 8 (MFG-E8) are two proteins whose interactions are essential to brain function. Both are highly expressed during periods of brain development when axonal pruning is very active. Recent studies have also shown both ITGαvβ₅ and MFG-E8 to be overexpressed in postmortem brains afflicted with Alzheimer's disease (AD). Despite this strong correlation, our understanding of the underlying mechanisms contributing to synapse elimination in AD is hindered by the lack of chemical tools to study them. Indeed, current chemical tools prevent visualization of protein interactions under endogenous environments. The development of new chemical tools to study protein interactions under endogenous environments without affecting function of both ITGαvβ₅ and MFG-E8 will provide a better understanding of their role in AD’s. This thesis details the synthesis of a fluorescent traceless-affinity probe (TAP) designed to selectively label ITGαvβ₅ to help address this knowledge gap. The fluorescent TAP consists of three smaller molecular components: a ITGαvβ₅ ligand, a cleavable electrophile linker and fluorescent reporter tag. The ITGαvβ₅ ligand and the cleavable electrophile linker were all individually synthesized and then coupled together with the fluorescent tag to assemble the TAP. Chapter 2 of this thesis focuses on the synthesis of a modified cilengitide allowing for late-stage derivatization at the meta position of the D-phenylalanine. Chapter 3 reviews precedents of TAPs, synthesis of cleavable electrophiles and linkers, and addresses future directions for the development of TAPs. Lastly chapter 4 concludes with a detailed account of the synthetic steps performed and the challenges faced towards assembling the final desired TAPs. Overall, the synthesis of a novel probe described in this thesis serves as a versatile probe construct with late-stage modularity towards the development of TAP to selectively target ITGαvβ₅. The synthetic routes established in both chapter 3 and 4 constitute significant progress towards a unique probe in the hopes to label ITGαvβ₅ without perturbing function under endogenous conditions.

Text

2025-04-23

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/90740

Chemistry

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/