Thesis Defence: Synthesis of a Traceless-Affinity Probe to Selectively Label Integrin Alpha V Beta Five in Live Cells
March 26 at 12:00 pm - 4:00 pm
Raphael Poirier, supervised by Dr. Fred Menard, will defend their thesis titled “Synthesis of a Traceless-Affinity Probe to Selectively Label Integrin Alpha V Beta Five in Live Cells” in partial fulfillment of the requirements for the degree of Master of Science in Chemistry.
An abstract for Raphael Poirier’s thesis is included below.
Defences are open to all members of the campus community as well as the general public. Registration is not required for in-person defences.
ABSTRACT
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 both novel TAPs described in this thesis, serve as a versatile probe construct with late-stage modularity towards the development of TAPs to selectively target ITGαvβ5. The synthetic routes established in both chapter 3 and 4 constitute significant progress towards a unique TAP to label ITGαvβ5 under endogenous conditions without perturbing function.
