Know thy neighbor: the role of diffusion and contact area on cell-cell signaling

Communication between cells plays a crucial role during the development and maintenance of tissues in higher organisms. Many intercellular signaling systems rely on direct cell-cell contacts to transduce signaling between neighboring cells. For example, the Notch signaling pathway involves interaction between membrane-bound receptors on one cell and membrane-bound ligands on a neighboring cell. While the components involved in these signaling systems (i.e. receptors, ligands, and various regulators) have been identified, we still know very little about the biophysics affecting these processes. What are the dynamics controlling the interactions between receptors and ligands on the boundary between cells? How do the properties of this boundary between cells (e.g. size of contact area) affect signaling? In this talk I will describe our efforts to address these questions using a combination of quantitative live cell imaging and mathematical modeling. We measure the diffusion and endocytosis rates of receptors and ligands on the cell membrane and show how these processes affect the ability of cells to communicate. Our results have implications on the way we understand developmental processes relying on such signaling systems.