Effect of Rho A on transforming growth factor β1-induced rat hepatic stellate cell migration.

Background Although the migration of hepatic stellate cells ( HSCs) is essential to the hepatic fibrotic response, the intracellular and extracellular signals that regulate their migration are poorly understood. Aims To investigate the role of Rho guanosine triphosphatase (Rho GTPase) signalling, specifically via RhoA, in transforming growth factor β1 ( TGFβ1)-induced HSC migration. Methods Both primary rat HSCs and the HSC-T6 rat hepatic stellate cell line were used in this study. Cell migration was evaluated using the Transwell Boyden Chamber assay, whereas cytoskeletal changes were observed using laser confocal microscopy. Western blotting was used to detect the expression of Rho GTPases (RhoA, Rac1 and Cdc42) in HSCs, and their activation was determined using glutathione S-transferase ( GST) pull-down assays. Finally, the specific effects of RhoA on TGFβ1-induced cell migration were analysed in HSC-T6 cells stably transfected with constitutively active ( CA, Q63L) or dominant-negative ( DN, T19N) RhoA mutants. Results Transforming growth factor β1 induced cytoskeletal remodelling and migration of rat HSCs following RhoA activation. The level of RhoA activation determined the motility of the HSCs. Conclusions These findings broaden our understanding of the intracellular and extracellular signals that regulate HSC migration. Furthermore, RhoA may be a candidate therapeutic target for hepatic fibrosis. [ABSTRACT FROM AUTHOR]