Downregulation of Hes1 expression in experimental biliary atresia and its effects on bile duct structure

AIM To analyze the expression and function of the notch signaling target gene Hesl in a rhesus rotavirus-induced mouse biliary atresia model. METHODS The morphologies of biliary epithelial cells in biliary atresia patients and in a mouse model were examined by immunohistochemical staining. Then, the differential expression of Notch signaling pathway-related molecules was investigated. Further, the effects of the siRNAmediated inhibition of Hesl expression were examined using a biliary epithelial cell 3D culture system. RESULTS Both immature (EpCAM(+)) and mature (CK19(+)) biliary epithelial cells were detected in the livers of biliary atresia patients without a ductile structure and in the mouse model with a distorted bile duct structure. The hepatic expression of transcripts for most Notch signaling molecules were significantly reduced on day 7 but recovered to normal levels by day 14, except for the target molecule Hesl, which still exhibited lower mRNA and protein levels. Expression of the Hesl transcriptional co-regulator, RBP-J(k) was also reduced. A 3D gel culture system promoted the maturation of immature biliary epithelial cells, with increased expression of CK19(+) cells and the formation of a duct-like structure. The administration of Hesl siRNA blocked this process. As a result, the cells remained in an immature state, and no duct-like structure was observed. CONCLUSION Our data indicated that Hesl might contribute to the maturation and the cellular structure organization of biliary epithelial cells, which provides new insight into understanding the pathology of biliary atresia.