Glutathione S-Transferase Pi Regulates Endothelial Permeability Through Inhibiting Actin Polymerization

Background:The precise regulation of vascular endothelial cell permeability is the basis of sustaining homeostasis and normal physiological functions of various organs.Inflammation-induced injury of endothelial barrier function is in several pathological conditions including atherosclerosis,ischemia and sepsis.The cytoskeletal proteins and adherin junctions are the main material basis of endothelial cell barrier.Endothelial cytoskeleton proteins,especially fibrous actin(F-actin),are involved in the maintenance of endothelial cell morphology,extracellular matrix adhesion and intercellular junction and other physiologic functions.F-actin remodeling is one of the important pathological mechanisms of vascular endothelial permeability induced by inflammatory stimulation.The mechanism of maintain the barrier function of endothelial cells against the proinflammatory stress is not clear at present.TNF-? is the major proinflammatory cytokines in early inflammation,which could cause the dysfunction of endothelial barrier and the increase of vascular permeability.It was the first time to find out the role of GSTpi in inflammatory responses and inhibition of proliferation and migration of vascular smooth muscle cells in our previous study.We suspect that GSTpi may have the function of regulating vascular endothelial permeability.Objective:In this study.the human umbilical vein endothelial cells cultured in vitro,the objective is to investigate the relationship between GSTpi and vascular endothelial cell permeability induced by TNF-?.We did pilot study whether the interaction between GSTpi and p38MAPK/MK2/HSP27 signal transduction pathway participates in the change of permeability of vascular endothelial cells mediated by TNF-?.Method:We used transwell permeability assay method to test the influence of GSTpi and its transferase activity on the endothelial permeability induced by TNF-?.We used the Laser confocal microscopy technology to observe the influence of GSTpi and its transferase activity on TNF-? induced actin remodeling.The western blot was used to test the influence of GSTpi on the TNF-? activated p38MAPK/MK2/HSP27.Result:The research show that GSTpi reduce the formation of stress fibers and decrease the endothelial permeability induced by TNF-? by restraining actin remodeling,and it has nothing to do with the transferase activity.Because the closely relationship between actin remodeling and HSP27 phosphorylation,when we study the mechanism of GSTpi inhibiting the actin remodeling to form stress fibers,we find that GSTpi inhibit the phosphorylation of p38MAPK and downstream substrate HSP27 induced by TNF-?.Conclusion:GSTpi inhibited TNF-? induced actin remodeling,stress fiber forming and endothelial permeability increasing by inhibiting TNF-?-induced activation of p38MAPK/MK2/HSP27 signaling pathway.