Location: HSB G-328, 10:30am (unless otherwise noted)
January 23, 2014
Xuefeng Wang, University of Illinois at Urbana-Champaign
Host: Stan Froehner
Mammalian cells sense external mechanical signals and accordingly direct many important functions such as cell adhesion, neuron growth, stem cell differentiation and embryo development. Integrins on cell membrane bind to external ligands on the local matrix and form integrin-ligand bonds. Cells apply tensions on these bonds and process mechanical feedbacks to activate downstream cellular functions. To study these molecular tensions, I developed a technique called tension gauge tether (TGT). The ligand is immobilized to a surface through a rupturable tether which serves as a molecular gauge to restrict the receptor-ligand tension. Using a range of tethers with tunable tension tolerances, I discovered that cells apply a universal maximum tension of about 40 piconewtons (pN) to single integrin-ligand bonds during initial adhesion. I also discovered that less than 12 pN is required to activate Notch receptors involved in intercellular communication. Aside from simply measuring the tension, TGT can also provide well-defined mechanical perturbations to cellular functions and a novel avenue to study cell mechanics at the molecular level. In the future, I will continue to develop other tether-based methods for cellular force measurements and perturbations and apply them to study mechanical–involved processes such as focal adhesion assembly, endocytosis, and neuron development.