Role of TLR4-Mediated PI3K/AKT/GSK-3βSignaling Pathway in Apoptosis of Rat Hepatocytes

Abstract

We investigated the mechanism of the Toll-like receptor 4- (TLR4-) mediated PI3K/AKT/GSK-3βsignaling pathway in rat hepatocytes apoptosis induced by LPS. The cultured rat hepatocytes were treated with LPS alone or first pretreated with TLR4 inhibitor, AKT inhibitor, and GSK-3βinhibitor, respectively, and then stimulated with the same dose of LPS. Cell viability, cell apoptotic rate, and apoptosis morphology were assessed; the level of P-AKTSer473, P-GSK-3βSer9, and active Caspase-3 and the ratio of Bax/Bcl-2 were evaluated. The results indicated that cell viability decreased, while cell apoptotic rate increased with time after LPS stimulation. The expression of P-AKTSer473and P-GSK-3βSer9in the LPS group decreased compared with the control, while the level of active Caspase-3 and the ratio of Bax/Bcl-2 were significantly increased. These effects were attenuated by pretreatment with CLI-095. In addition, the apoptotic ratio decreased after pretreatment with LiCl but increased following pretreatment with LY294002. The expression of P-AKTSer473further decreased following pretreatment with LY294002 and the expression of P-GSK-3βSer9increased following pretreatment with LiCl. Moreover, pretreatment with CLI-095 weakened LPS-induced nuclear translocation of GSK-3β. Our findings suggest that the TLR4-mediated PI3K/AKT/GSK-3βsignaling pathway is present in rat hepatocytes and participates in apoptosis of BRL-3A cells.