Suppression of Rho activation process due to simulated microgravity induced cytoskeletal disorganization

Abstract

Microgravity has been shown to affect the formation of cytoskeletal fibers in flight experiments; however, the mechanism of gravity sensing has not yet been elucidated. It is well known that the small GTPase RhoA regulates the cytoskeletal components. In this study, we evaluated the effect of simulated microgravity that affects actin fiber remodeling and tubulin assembly in cells by using biochemical and molecular biological methods. We found that RhoA had wide intracellular distribution in the clinorotated cells. Although the protein expression of RhoA was upregulated, the actin stress fibers and tubulin assembly was disturbed. Messenger RNA fingerprinting results show that gene expression of LARG might be suppressed under simulated microgravity. These results suggest that the Rho activation process is suppressed by simulated microgravity, thereby inducing the disorganization of these cytoskeletal fibers.