THE CYTOSKELETAL EFFECTS OF NITRIC OXIDE (NO) ON HEPATOCYTE GROWTH FACTOR (HGF)-INDUCED EPITHELIAL SCATTERING IN VITRO AND RHOA IN SILICO

Abstract

The importance of Nitric Oxide (NO) is well-characterized in endothelial cells, where it contributes to vasodilation. In this thesis, we studied NO signaling in epithelial MDCK (Madin-Darby Canine Kidney) cells, with experimental studies of HGF-induced cell migration, and theoretical simulations of the cross-talk between NO and RhoA. Experiments showed NO to be important for HGF-induced migration of MDCK, and further work demonstrated that phosphorylation of the cytoskeletal regulator VASP (Vasodilator Stimulated Protein) mediated the effect of NO on cell-cell junction disruption. Computational modeling of the mutual antagonism between NO and RhoA, suggested that the system is capable of bistability. Upon updating the model with the reactions involving mechanical tension, the robustness of bistability increased greatly. Since NO and RhoA are master regulators of cell relaxation and contraction respectively, this work sheds light on important new questions of time-scale and reaction strength, for understanding how NO and RhoA regulate cytoskeletal mechanics.