Vesicle fusion regulation in metabolism

About This Grant

PROJECT SUMMARY Many metabolic responses involve the trafficking of proteins within the endomembrane system. A major branch of membrane protein trafficking is vesicle fusion, which entails the merging of membrane-enclosed vesicles with their target membranes. Vesicle fusion mediates key metabolic processes, including the translocation of the glucose transporter GLUT4, insulin secretion, glucagon release, and GLP-1 secretion. Imbalances in these vesicle fusion processes are associated with metabolic disorders such as insulin resistance (IR) and type 2 diabetes (T2D). To devise effective therapeutic strategies for these disorders, it is crucial to understand how protein-protein networks mediate and regulate vesicle fusion in these metabolic pathways. Our research focuses on the vesicle fusion pathway critical for the insulin-dependent translocation of GLUT4 in adipocytes and muscle cells. In our preliminary studies, we developed CRISPR-based genetic platforms and identified new players in the vesicle fusion pathway. Additionally, through biochemical and biophysical assays, we uncovered novel protein-protein and protein-membrane binding modes in GLUT4 vesicle fusion. In this work, we aim to expand these preliminary findings to elucidate how the soluble and membrane proteins act in concert to mediate and regulate the vesicle fusion reaction and to understand how fusion kinetics are affected by changes in lipid composition. Our genetic experiments employ cultured adipose and muscle cells differentiated from progenitor cells, as well as genetically modified mouse strains. We will also use a novel platform of mature human adipocytes derived from differentiation of human pluripotent stem cells. As a crucial step towards grasping the molecular basis of IR, we will use mouse models to explore how a high-fat diet-induced IR condition affects vesicle fusion mediators. The experiments proposed here are expected to provide key mechanistic insights into the molecular basis of metabolic vesicle fusion, and will pave the way for understanding IR and T2D. Ultimately, these findings will likely contribute to the development of new treatments for these metabolic disorders.