Direction 1: Visualize and study single molecular tensions in cells.
Utilizing CFN (cellular force nanoscopy) developed in our lab, we can literally see single molecular force (the bright sparks in the video) in live cells. Based on the imaged molecular tensions, we achieve super-resolution cellular force imaging by molecule localization. CFN provides an cutting-edge imaging tool for the study of force-structure interplay in live cells with ultra sensitivity and resolution. We are applying CFN to study the force and structural formation in some smallest adhesion units in cells.
Direction 2: Study cell mechanobiology of platelets and keratocytes
By converting force signal to fluorescent signal, integrative tension sensor (ITS) enables cellular force mapping directly by fluorescence imaging, therefore inheriting many advantages of fluorescence microscopy such as high resolution, high sensitivity and rapid image acquisition. With ITS, we are able to calibrate and map integrin tensions in real time in live cells such as platelets and migrating keratocytes. The cellular force mapping with high temporal and spatial resolution helps us explore the roles of integrin tensions in platelet adhesion, contraction and keratocyte protrusion and retraction. We are also studying the relation between platelet force maps and platelet health conditions, in the hope of developing a platelet force assay to assess bleeding risk in patients.
Direction 3: Harness cell mechanotransduction by molecular tension control
It is well recognized that cells are able to sense mechanical properties of the matrix and regulate their functions accordingly. For example, cells can perform directional migration following mechanical cues such as substrate stiffness gradient, a phenomenon called mechanotaxis. As another example, stem cells differentiate to different cell types dependent on the stiffness of ECM. Researchers have been extensively applying bulk mechanical cues such as elasticity or topology of substrates to influence cell and tissue functions, for both research and medical purposes.
Tension gauge tether (TGT) enables quantitative control of cellular force at the molecular level. TGT globally restricts molecular tensions on mechano-sensitive receptors such as integrins under a designed level Ttol, providing a unique tension knock-down technique. Previously, we revealed that cell migration and polarization are compromised if integrin molecular tension is restricted under 54 pN using TGT, focal adhesion formation is inhibited if integrin tension is restricted under 43 pN, and cell adhesion & spreading is inhibited if tension is restricted under 33 pN. This series of experiments demonstrated that TGT provides a molecular force control to influence a variety of cellular functions.
We study kinase (FAK, Src, Rac and SYK etc) activation, cell mechanotaxis, Neurogenesis and Neuron Axon guidance and Angiogenesis on TGT platform. To transform the research to biomedical applications, we propose to develop TGT-grafted biomaterials that have the potential to provide a global and quantitative force control on mechano-sensitive receptors, and eventually manipulate specific cellular functions.
