ABSTRACT
Objective: To study the regulatory role of GLI1/GLI2, a nuclear transcription factor of the Sonic hedgehog (Shh) signaling pathway, in epithelial-mesenchymal transition (EMT) related to hepatic fibrosis in patients with biliary atresia (BA). Methods: The messenger RNA (mRNA) and protein expression levels of GLI1/GLI2, Snail/Slug, and other Shh- and EMT-related cytokines were tested in the liver tissues of BA patients and animals. Then, GLI1/GLI2 was silenced and overexpressed in mouse intrahepatic bile duct epithelial cells (mIBECs) and BA animals to investigate changes in the mRNA and protein expression of EMT key factors and liver fibrosis indicators. After silencing and overexpression of GLI1/GLI2, immunofluorescence was used to detect the expression of cytokeratin-19 (CK19) and α-smooth muscle actin (α-SMA) in mIBECs, and hematoxylin and eosin (HE) staining and Masson staining were used to observe the degree of liver fibrosis in the BA animals. Results: Compared with the control, the mRNA and protein expression levels of GLI2, Snail, vimentin, and α-SMA were significantly increased and those of E-cadherin were significantly decreased in liver tissue from BA patients and animals. Overexpression of GLI2 increased the mRNA and protein expression levels of Snail, vimentin, and α-SMA and that of E-cadherin was significantly decreased in mIBECs and BA animals. After GLI2 silencing, the opposite pattern was observed. Immunofluorescence detection showed enhanced expression of the bile duct epithelial cell marker CK19 in mIBECs after GLI2 silencing and enhanced expression of the mesenchymal cell marker α-SMA after GLI2 overexpression. HE and Masson staining suggested that the GLI2-overexpressing group had a significantly higher degree of fibrosis. Conclusion: The Shh signaling pathway plays an important role in fibrogenesis in BA. GLI2 can significantly regulate EMT in mIBECs and livers of BA mice.
ABSTRACT
Objective:To investigate the role of nuclear transcription factor Gli1/Gli2 of the sonic hedgehog (Shh) signaling pathway in the hepatic epithelial mesenchymal transition (EMT) of biliary atresia mice caused by Rhesus rotavirus (RRV) infection.Methods:The biliary atresia model in mice was generated by RRV infection.Mice were divided into normal group, model group, Gli1 overexpression group, Gli1 shRNA group, Gli2 overexpression group and Gli2 shRNA group.Real-time fluorescence quantitative polymerase chain reaction and Western blot were used to detect the mRNA and protein expressions of regulatory factors for EMT (Snail/Slug) and characteristic cytokines of EMT [Vimentin, α-smooth muscle actin(α-SMA), E-cadherin] in mouse liver tissues.Additionally, hematoxylin-eosin staining and Masson staining were performed to calculate the percentage of liver fibrous tissue expression area.The data were analyzed by One- Way ANOVA and LSD- t test. Results:The relative mRNA expression of Snail, Slug, Vimentin, α-SMA and E-cadherin in Gli2 overexpression group, Gli2 shRNA group and model group were 15.13±3.40, 5.48±0.46, 8.78±1.06, 12.40±2.18 and 3.06±0.53; 3.73±1.16, 5.62±1.75, 3.56±1.06, 3.88±1.16 and 10.51±1.83; 8.13±1.27, 5.32±0.98, 5.05±0.98, 4.02±0.77 and 5.12±1.60.Compared with those of the model group, mRNA levels of Snail, Vimentin and α-SMA were significantly higher in Gli2 overexpression group, while that of E-cadherin was significantly lower( t=4.53, 5.29, 8.12, -2.13; all P<0.05); compared with those of the model group, mRNA levels of Snail and Vimentin in Gli2 shRNA group significantly decreased, while that of E-cadherin significantly increased( t=-2.86, -2.12, 5.62; all P<0.05). In Gli2 overexpression group, Gli2 shRNA group and model group, the protein levels of Snail, Slug, Vimentin, α-SMA and E-cadherin were 2.02±0.39, 0.31±0.08, 0.95±0.17, 1.07±0.17 and 0.42±0.06; 0.53±0.13, 0.40±0.18, 0.20±0.04, 0.28±0.07 and 1.09±0.31; 0.70±0.15, 0.42±0.22, 0.64±0.13, 0.81±0.11 and 0.42±0.09.Compared with those of the model group, protein levels of Snail, Vimentin and α-SMA were significantly higher in Gli2 overexpression group( t=12.71, 4.28, 3.70; all P<0.05); compared with those of the model group, protein levels of Vimentin and α-SMA in Gli2 shRNA group significantly decreased, while that of E-cadherin significantly increased( t=-6.14, -7.57, 5.96; all P<0.05). However, no significant change trend were detected in expression levels of characteristic cytokines of EMT between Gli1 overexpression group and Gli1 shRNA group.The area percentage of liver fiber expression in normal group, model group, Gli1 overexpression group, Gli1 shRNA group, Gli2 overexpression group and Gli2 shRNA group were (1.03±0.58)%, (33.02±11.39)%, (39.81±5.67)%, (26.06±1.29)%, (49.81±8.57)% and (17.55±0.66)%, respectively.Besides, in terms of percentage of area expressed in liver fiber tissue, the Gli2 overexpression group and Gli2 shRNA group were statistically significant compared with the model group( t=3.21, -2.96; all P<0.05), while the Gli1 overexpression group and Gli1 shRNA group were not statistically significant compared with the model group (all P>0.05). Conclusions:The Shh signaling pathway plays an important role in liver fibrosis in mice with biliary atresia.Gli2, a key transcription factor of Shh signaling pathway, can significantly regulate liver EMT process in mice with biliary atresi.
