| Background:Hepatic fibrosis represents the wound healing response to liver injury from a wide variety of etiologies, it is the intermediate stage of development of chronic liver disease to cirrhosis. Hepatic fibrosis is a complex process by a variety of cells and cytokines, and hepatic stellate cells (HSC) are the major target cells for variety of cytokines. Effects of cytokines on HSCthrough complex signal transduction pathways, the pathways are classical TGFβ1/Smad, Mitogen-activated protein kinase (MAPK) and JAK/STAT signal transduction pathways. In recent years, the efftct of the MAPK signaling pathway in hepatic fibrosis become a hot spot. Extracellular signal-regulated kinase (ERK)1/2, a member of MAPK family, is the relatively clear signal transduction pathway. ERK1/2signaling pathway can be activated by variety of cytokines and mitotic, including transforming growth factor β1(TGFβ1, the strongest factor of profibrogenic), and than regulate the biological activity of HSC.Insulin-like growth factor binding protein related protein1(IGFBPrPl) is a soluble glycoprotein secreted by a variety of cells, its biological function is not yet entirely explicit. Professor Lixin Liu’subject team discovered that IGFBPrP1in liver tissue of patients with fibrosis was significantly higher than that in normal controls, and the expression of IGFBPrPl was positive correlation with TGFβ1. IGFBPrPl by intraperitoneal injection can induce hepatic fibrosis in Wild-type mice, and the expressions of TGFβ1and p-Smad2/3were also increased in liver tissue at the same time.Whether IGFBPrPl can activate the TGFβ1/Smad3and ERK1/2signaling pathways? There was no reported. In order to clarify these issues, we designed this project. Part I The effects of TGFβ1/Smad3signal pathway in hepatic stellate cells induced by IGFBPrPlObjective:To investigate the effect of TGFβ1/Smad3signal pathway in hepatic stellate cells induced by IGFBPrPl.Methods:LX-2cells were cultured in vitro and established respectively the control group (incubated with equal phosphate buffer saline) and IGFBPrPl group (IGFBPrPl treatment with30μg/L), then the supernatant were collected and whole-cell proteins were extracted after24hours. The protein expressions of type I collagen, fibronectin and TGFβ1in supernate and Smad3, p-Smad2/3, in cells were determined by Western blot.Results:1. Effects of IGFBPrPl on the expressions of type I collagen and fibronectin in LX-2cells:The protein expressions of type I collagen and fibronectin were increased significantly in IGFBPrPl group compared to the control group (type I collagen:0.68±0.07vs0.49±0.05,t=4.157, P<0.05, fibronectin:0.54±0.07vs0.37±0.04,t=3.982, P<0.05).2. Effects of IGFBPrPl on the expression of TGFβ1in LX-2cells:The protein expression of TGFβ1was increased significantly in IGFBPrPl group compared to the control group (0.35±0.05vs0.21±0.04,t=3.906,P<0.05).3. Effects of IGFBPrPl on the expressions of Smad3and p-Smad2/3in LX-2cells:The protein expression of Smad3was not changed significantly in IGFBPrPl group compared to the control group (0.65±0.05vs0.64±0.05,t=0.084,P>0.05), the protein expression of p-Smad2/3was increased significantly in IGFBPrPl group compared to the control group (0.70±0.05vs0.46±0.03,,t=8.050,P<0.05), the ratio of p-Smad2/3and Smad3was also significantly increased (1.10±0.12vs0.72±0.05,t=5.181,P<0.05).Conclusions:1. IGFBPrPl can increase the secretion of both type I collagen and fibronectin which are the principal component of extracellular matrix in LX-2cells in vitro.2. IGFBPrP1can promote the production of TGFβ1in LX-2cells in vitro.3. IGFBPrPl can increase the phosphorylation of Smad3in LX-2cells in vitro. Part II The effects of extracellular signal-regulated kinase1/2signal pathway signal pathway in hepatic stellate cells induced by IGFBPrPlObjective:To investigate the effect of extracellular signal-regulated kinase1/2(ERK1/2) signal pathway in hepatic stellate cells induced by IGFBPrPl.Methods:LX-2cells were cultured in vitro and established respectively the control group (incubated with equal phosphate buffer saline) and IGFBPrPl group (IGFBPrPl treatment with30μg/L), then the whole-cell proteins were extracted after24hours. The protein expressions of ERK1/2and p-ERK1/2in cells were determined by Western blot.Results:Effects of IGFBPrPl on the expressions of ERK1/2and p-ERK1/2in LX-2cells:The expression of ERK1/2was not changed significantly in IGFBPrPl group compared to the control group (0.55±0.07vs0.54±0.05,t=0.286,P>0.05), the protein expression of p-ERK1/2was increased significantly in IGFBPrPl group compared to the control group (0.33±0.04vs0.17±0.02,t=7.538,P<0.05), The ratio of p-ERK1/2and ERK1/2was also increased significantly in IGFBPrPl group compared to the control group (0.61+0.07vs0.31+0.04, t=7.535,P<0.05).Conclusions:IGFBPrPl can increase the phosphorylation of ERK1/2in LX-2cells in vitro. |
PDF Full Text Request