Molecular Mechanisms Underlying TRPM3 Regulation in the Cell Membrane

SUMMARY Membrane proteins and lipids are organized into signaling domains in the cell membrane that are hundreds of nanometers in size. These signaling domains are essential for the efficiency and specificity required for cell signaling. The long-term vision of my research program is to determine the molecular compositions and structures of these membrane protein signaling complexes and understand how their organization results in their physiological function. This overall vision will be fulfilled through two independent tasks. One is to determine the molecular mechanisms underlying individual components in a signaling pathway. The other is to directly study the complex as a whole to understand how different components are assembled with each other. In the next five years, my goal is to exercise these two tasks on a specific membrane protein ─ the TRPM3 ion channel. TRPM3 plays a critical role in nociceptor neurons and mediates inflammatory hyperalgesia and pain sensation. The activity of TRPM3 is tightly regulated by the G protein-coupled receptor (GPCR) signaling pathway. Specifically, we will determine the structures and activities of individual TRPM3 channels in isolation and in cell membranes to understand the molecular details governing its transition between closed, open, and desensitized states. We will also determine the compositions and structures of the TRPM3 signaling complex in the cell membrane to understand how the organization of lipid and protein molecules contributes to TRPM3 signaling efficacy. We will use electrophysiological recordings in cells and in reconstituted membranes to isolate the contributions from individual protein and lipid partners. The results from this proposal will not only advance our molecular understanding of the TRPM3 function but also contribute to the emerging field of integrative structural biology, where we study the structure of signaling complexes in the native environment using a multitude of atomistic and molecular approaches. Our efforts will also lead to the development of new methods to study TRPM3 ion channels in their native environments that are broadly applicable to other membrane proteins and signaling pathways.