TNF-a induce the F-actin arrangement and permeability increase in endothelial cells by RhoA-ERK1/2 pathway

Background This study aimed to determine the effects of tumor necrosis factor(TNF-a) on endothelial cytoskeleton morphology and permeability,and to detect the underlying signaling mechanisms involved in these responses. Methods Cultured endothelial cells(ECs) were exposed to TNF-a,and EC cytoskeletal changes were evaluated by observing fluorescence of F-actin following ligation with labeled antibodies.Endothelial permeability was detected by measuring the flux of HRP-albumin across the EC monolayers.To explore the signaling pathways behind TNF-a-induced EC alteration, ECs were treated with either the RhoGTPase inhibitor Y27632 or the MAPK inhibitors PD98059 and SB203580 before TNF-a administration.To further elucidate possible involvement of the RhoA and ERK pathways in TNF-induced EC changes,retrovirus-carried recombinant dominant-negative forms and constitutive-activative forms of RhoA,namely T19NRhoA and Q63LRhoA,were pre-infect-ed into ECs prior to TNF-a exposure.Results TNF-a induced F-actin cytoskeleton rearrangement,as well as EC hyperpermeability in a dose and time-dependent manner.The effects were attenuated in cells pretreated with Y27632 or PD98059,respectively.EC pre-infection with T19NRhoA also alleviated the effects of TNF-a.Furthermore,retrovirus-mediated administration of activated forms of Q63LRhoA alone induced rearrangement of F-actin and hyperpermeability as well as induced the activation of pERK.Conclusions These results indicate that RhoA-ERK/MAPK signal pathway play important roles in the mediation of TNF-a induced EC barrier dysfunction associated with morphological changes of the Factin.