In this project, the investigators will develop a new experimental and computational platform to answer the longstanding biological question of how cellular receptors generate biochemical signals as they move among various subcellular compartments. By helping to quantitatively resolve certain apparently conflicting observations that have recently been made within a biological system previously thought to be well understood, this project will add fundamentally new understanding of basic mechanisms of cell signaling that may have implications across numerous receptor systems in cell biology. Moreover, due to the broadly important role that receptors, and the biochemical signals they generate, play in virtually every biological process, the new quantitative understanding gained will ultimately impact ongoing efforts to optimally engineer receptor-mediated signaling. This project also includes a broad and detailed set of integrated educational objectives that leverage the specific scientific objectives and activities of this project to reach students at different training stages and from diverse backgrounds. These education and outreach activities involve innovation upon existing programs at the partnering institutions as well as the creation of new outreach efforts that will target larger audiences, such as a summer academy of science for high school students and a collaboration with the Museum of Science and Industry in Tampa, FL to develop a live interaction program on cell signaling.
The biochemical signaling that results upon ligand binding to receptor tyrosine kinases is accompanied by receptor clustering and internalization, or endocytosis. While it has been understood for decades that endocytosis enables cells to degrade or recycle receptors, the question of how endocytosis ultimately impacts downstream signal propagation remains wide open. For example, even for the highly studied epidermal growth factor receptor (EGFR) the literature contains highly cited, yet conflicting reports that conclude that EGFR endocytosis either promotes or impedes downstream signaling through the extracellular regulated kinase (ERK) pathway. In this project, the investigators will explore the hypothesis that the intrinsic complexity of the spatiotemporal signaling regulatory mechanisms creates parameter spaces for both answers to be true depending on the cellular context. The complexity of the receptor trafficking and signaling system cannot be fully dissected, however, without integrating quantitative experimental measurements that faithfully reflect cell biology with spatiotemporal computational models. Accordingly, the overarching goal of this project is to combine novel live-cell imaging of gene-edited cell systems with mechanistic models that capture system complexity with unprecedented detail to resolve the kinds of conflicting reports previously mentioned, as well as more recent surprising observations that certain proteins conventionally thought to remain in complex during signal transduction may become physically separated through trafficking processes. Ultimately, the proposed integration of gene-edited cell systems, quantitative live-cell imaging and biochemical measurements, and a spatiotemporal computational model will lead to an entirely new quantitative platform to answer these kinds of questions for EGFR and other receptor signaling systems.
