Endoplasmic reticulum protein 29 inhibits epithelial-mesenchymal-transformation in placental trophoblast cells and promotes the development of intrahepatic cholestasis of pregnancy in pregnant rats

Abstract

Background Intrahepatic cholestasis of pregnancy (ICP) is a common pregnancy specific liver disease, which has little impact on the mother and mainly causes adverse fetal outcomes. Endoplasmic reticulum protein 29 (ERp29) plays a key role in protein folding, transport and secretion, and participates in biological events such as apoptosis, oxidative stress, lipid metabolism, immune regulation and so on. Epithelial mesenchymal transformation (EMT) is the process of epithelial cells losing polarity and adhesion, and transforming into mesenchymal like phenotype through migration. Methods Subcutaneous injection of ethinyl estradiol (E2) was used to induce ICP in pregnant rats, and serum TBA, ALT and AST were detected to test whether the animal model was successfully constructed. ERp29 and EMT related molecules were detected by immunohistochemistry and western blotting. Taurocholic acid (TCA) was used to simulate the ICP environment, and TGF-β1 was added to induce the EMT process. CCK8 and TUNEL were used to detect the level of cell apoptosis. The scratch, migration, and invasion test were used to detect the EMT process of cells. ERp29 overexpression/knockdown vector were constructed and transfected to verify the role of ERp29 in the EMT process. Results The ICP animal model was successfully constructed. ERp29 in the placenta tissue of the ICP pregnant rats increased significantly, and the level of apoptosis increased. Compared with the normal, the placental tissues of the ICP group had high expression of E-cadherin and low expression of N-cadherin, snail1, vimentin. After HTR-8/Svneo cells were induced by TCA, EMT was inhibited, while the ERp29 increased. Knockdown of ERp29 reduced the inhibition of cell EMT. After the ERp29 knockdown vector was transfected into pregnant rats by adenovirus, the degree of inhibiting EMT in the placenta tissue of pregnant rats was inhibited, and the ICP progress was alleviated. Conclusion The high level of ERp29 in placental trophoblast cells inhibits the EMT process and aggravates the occurrence and development of ICP.