The Influence of Membrane Lipids and Novel EphA2 Ligands on EphA2 Structure and Function

Receptor tyrosine kinase (RTK) signaling plays a critical role in human development and maintaining homeostasis. When these proteins are overexpressed and/or misregulated they often act as drivers for oncogenic phenotypes. While much is known about the structure and signaling outcomes of these receptors, there lacks an understanding of the factors that regulate their structural dynamics that are associated with a non-diseased versus a diseased state. It is further unknown how these structural dynamics coincide with cellular outcomes or activities. Here we develop SiMPull-POP to quantitatively capture the structural dynamics of the RTK EphA2 and characterize the factors that regulate these dynamics. Furthermore, we investigate the activity of EphA2-interacting partners as a function of the factors regulating EphA2’s structural changes. We find that cholesterol content inhibits oncogenic assembly and activation of EphA2 and this is mediated by homeostasis of the cAMP/PKA signaling axis (Chapter I). We further characterized how other RTKs, such as IGFR1, physically interact with EphA2 to inhibit ligand-induced EphA2 assembly (Chapter II). Lastly, we investigated how EphA2 is able to elicit differential assembly states and activation modes in response to novel EphA2 ligands (Chapter III). These findings add to the knowledge of the relationship between protein structure and function, which is vital to designing future therapeutics.