Study the role of integrin tension in cell migration, platelet functions and phagocytosis

Project Summary/Abstract Force is a fundamental element of life. On the cell membrane, along with the proteins that perceive biochemical signals, there are also diverse proteins serving as mechano-sensitive receptors. Through these receptors, cells attach to the local matrix or adjacent cells, producing forces that regulate a range of cellular functions, including cell adhesion, migration, differentiation, and proliferation. Over the long term, these forces also play significant roles in various physiological processes such as biological development, cancer metastasis, immune response and hemostasis. Despite their importance, studying receptor-transmitted forces has proven challenging, given their invisible nature and minuscule force intensity. To visualize, calibrate and manipulate these elusive forces, our laboratory have developed a series of molecular tension tools. Among them is a tension sensor named ITS (integrative tension sensor), that readily visualizes molecular forces in live cells by converting force to fluorescence, and a tension modulator named TGT (tension gauge tether), that globally knocks down molecular tensions in live cells to a defined level. With ITS and TGT, lately we have identified three novel integrin-mediated force-bearing structures: an ultra-thin line of integrins at the cell protrusion site, a phagocytic adhesion ring (PAR) around surface-bound particles under macrophages, and force foci in adherent platelets. We hypothesize that integrins and associated forces in these structures play important roles in cell migration, macrophage-mediated phagocytosis, and platelet-mediated hemostasis. A MIRA grant uniquely provides the flexibility allowing our lab to explore these diverse research directions in the field of cell mechanobiology. In the next five years, our lab will continue to develop state-of-the-art molecular tension sensors, and combine them with biochemical approaches and super-resolution microscopy to investigate the range, source, dynamics, and function of integrin tensions in these structures. The research will reveal how cells exert and control integrin tensions with submicron precision at the thin force lines to coordinate cell migration and spreading. It will also unveil the biomechanical role of PARs and the associated integrin tensions during the internalization of surface-bound particles by macrophages, revealing a new mechanism of phagocytosis. For the study of platelet functions, we will develop tension sensors selectively targeting the vWF (Von Willebrand factor) receptor, collagen receptors (integrin α2β1 and glycoprotein VI), and the fibrinogen receptors (integrin αIIbβ3) in the force foci of platelets, systematically investigating the role of these receptors in platelet adhesion, activation and aggregation under shear stress during hemostasis. Overall, this project will reveal valuable insights into the mechanobiology of the three force- bearing structures and determine their critical roles in cell migration, phagocytosis, and platelet functions. The project will also provide the field with innovative molecular tension tools expected to be widely useful for the study of cell mechanobiology.