CAREER: Lipid Regulation of Receptor Tyrosine Kinases

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With this award, the Chemistry of Life Processes Program in the Chemistry Division is funding Dr. Adam W. Smith from the University of Akron to investigate lipid regulation of receptor tyrosine kinases. The surface of living cells is composed of a lipid membrane embedded with thousands of protein receptors. Dynamic associations between membrane proteins and lipids are integral to function, but resolving these interactions has proven to be extremely challenging. This project applies advanced fluorescence methods, and single-molecule imaging to measure lipid-protein interactions in biological membranes. The long-term goal is to develop a quantitative chemical model for the interface between plasma membrane lipids and a class of membrane proteins called receptor tyrosine kinases (RTKs). RTKs are integral membrane proteins that regulate cell growth and differentiation. The focus of this project is on two RTKs, EphA2 and EGFR. Integral with these research objectives is an education and broader impacts program that enhances STEM education at the University of Akron and provides materials and curriculum for enhanced laboratory instruction across the country. This includes the development of a 3D-printable, smartphone spectrometer (the SpecPhone) for implementation in university laboratory courses. The low cost and simplicity of the SpecPhone also make it accessible to K-12 students and citizens so that they can engage in real-world science problems. The broader impacts work creates new curriculum and teacher training workshops for K-12 STEM education, to participate in local Maker Fairs, and to develop protocols for a transformative citizen science project in the Lake Erie watershed.Lipids solvate membrane proteins and, in many cases, regulate their activity through direct, specific contacts. Many lipid-protein interactions are inferred from static structures or computer simulations; however, there is little experimental data to verify these interactions in situ and determine their kinetic and thermodynamic stability. This project uses advanced fluorescence methods, including pulsed-interleaved excitation fluorescence cross-correlation spectroscopy (PIE-FCCS) and single-molecule imaging to measure molecular associations in biological membranes. The long-term goal is to develop a quantitative chemical model for the interface between plasma membrane lipids and receptor tyrosine kinases (RTKs). Both the extracellular domain (ECD) and the intracellular domain (ICD) of RTKs associate directly with the plasma membrane, but the chemical details of the associations are not well-understood. This project focuses on two RTKs, EphA2 and EGFR. The central hypothesis is that anionic lipids bind these proteins and regulate their structure and activity. To test this hypothesis, we determine the affinity and specificity of anionic lipid binding to EGFR in model supported lipid bilayers. We also investigate the regulation of EphA2 structure and dynamics by anionic lipids in model membranes. Finally, we resolve the functional role of anionic lipid binding to EGFR. Achieving these objectives contributes to a systematic understanding of how the lipid-protein interface is affected by parameters like lipid charge, headgroup structure, solvent pH, and salt effects. The results significantly advance our understanding of the chemical interactions that guide cell communication. Integral with these research objectives is an education and broader impacts program that enhances STEM education at the University of Akron and provides materials and curriculum for enhanced laboratory instruction across the country. This includes the development of a 3D-printable, smartphone spectrometer (the SpecPhone) for implementation in university laboratory courses. The low cost and simplicity of the SpecPhone also make it accessible to K-12 students and citizens so that they can engage in real-world science problems. The focus of the broader impacts work is to create new curriculum and teacher training workshops for K-12 STEM education, to participate in local Maker Fairs, and to develop protocols for a transformative citizen science project in the Lake Erie watershed.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.