Reconstitution of the mechano-sensitive cadherin-catenin/F-actin complex - Tan, Jiongyi; Dunn, Alexander Robert; Nelson, William; Theriot, Julie; Weis, William I; Stanford University, Department of Biophysics (2016)
Cell-cell adhesion is essential for tissue development and maintenance. In epithelial tissue, the cadherin-catenin complex establishes this adhesion and associates with the actin cytoskeleton to do so. A long-standing hypothesis is that the cadherin-catenin complex binds actin filaments directly, but work using purified proteins challenged this idea in 2005. Since then, studies have found that the cadherin-catenin complex is sensitive to mechanical tension. As a result, we hypothesized that the complex requires tension to bind actin filaments. Results from an optical-trap assay supported this idea, and we concluded that cadherin-catenin complexes and actin filaments form two-state catch bonds, which last longer at intermediate levels of tension. Work of others suggested that association of vinculin with the cadherin-catenin complex is the molecular basis of the longer-lived catch bond state. Our follow-up work using the vinculin head domain, which binds the cadherin-catenin complex in solution but not actin filaments, demonstrated that association of vinculin lengthens the duration of actin bonds. Full-length vinculin, however, is an autoinhibited molecule that binds the cadherin-catenin /actin complex weakly. Thus, based on other studies, further work sought to test whether or not actomyosin-generated tension and abl-mediated phosphorylation were sufficient to increase this binding. Experiments conducted using a microscopy-based filament-binding assay showed that while tension and phosphorylation were not required for association of vinculin, they had an additive effect on the amount of bound vinculin. Altogether, my thesis work provided mechanistic insights into how mechanical tension affects the kinetics and composition of the cadherin-catenin/F-actin complex.
Submitted to the Department of Biophysics.
Thesis (Ph.D.)--Stanford University, 2016.
Rights: (c) Copyright 2016 by Jiongyi Tan
Rights: This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
Keywords: theses