Reprogramming factor Oct4 is crucial for transdifferentiation of hepatocytes to biliary epithelial cells
Location
Georgia
Start Date
12-5-2015 1:00 PM
Description
Transdifferentiation of liver epithelial cells (hepatocytes and biliary cells) into each other provides a rescue mechanism in liver disease under situations where either cell compartment fails to regenerate by itself. The mechanisms underlying such transdifferentiation of terminally differentiated epithelial cells are not fully elucidated. Recently we reported that adult rat liver expresses reprogramming factors Oct4, Nanog, and KLF4, and their expression is important for hepatocyte proliferation and liver regeneration. To test if reprogramming factor Oct4 plays a role in transdifferentiation of hepatocytes to BECs, we used the hepatocyte organoid culture: an in vitro hepatocyte to biliary transdifferentiation model. In this model, primary hepatocytes when plated on collagen coated roller bottles and cultured in presence of HGF, EGF, and dexamethasone, transdifferentiate to form BECs between 6-15 days in culture. We found that Oct3/4 is upregulated at day 6 in this model as assessed by mRNA and protein levels suggesting its possible involvement in transdifferentiation. When expression of Oct4 was blocked in hepatocytes using adenovirus containing Oct4 shRNA, there was a significant decrease in the number of biliary cells as compared to controls as assessed by biliary marker HNF1-beta, strongly supporting the role of Oct4 in transdifferentiation of hepatocyte to biliary epithelial cells. Moreover, Oct4 inhibited group shows significantly less SOX9, YAP, and Notch (also shown to be involved in transdifferentiation) expression as compared to controls. Experiments to investigate mechanisms through which Oct4 might regulate transdifferentiation are under way.
Reprogramming factor Oct4 is crucial for transdifferentiation of hepatocytes to biliary epithelial cells
Georgia
Transdifferentiation of liver epithelial cells (hepatocytes and biliary cells) into each other provides a rescue mechanism in liver disease under situations where either cell compartment fails to regenerate by itself. The mechanisms underlying such transdifferentiation of terminally differentiated epithelial cells are not fully elucidated. Recently we reported that adult rat liver expresses reprogramming factors Oct4, Nanog, and KLF4, and their expression is important for hepatocyte proliferation and liver regeneration. To test if reprogramming factor Oct4 plays a role in transdifferentiation of hepatocytes to BECs, we used the hepatocyte organoid culture: an in vitro hepatocyte to biliary transdifferentiation model. In this model, primary hepatocytes when plated on collagen coated roller bottles and cultured in presence of HGF, EGF, and dexamethasone, transdifferentiate to form BECs between 6-15 days in culture. We found that Oct3/4 is upregulated at day 6 in this model as assessed by mRNA and protein levels suggesting its possible involvement in transdifferentiation. When expression of Oct4 was blocked in hepatocytes using adenovirus containing Oct4 shRNA, there was a significant decrease in the number of biliary cells as compared to controls as assessed by biliary marker HNF1-beta, strongly supporting the role of Oct4 in transdifferentiation of hepatocyte to biliary epithelial cells. Moreover, Oct4 inhibited group shows significantly less SOX9, YAP, and Notch (also shown to be involved in transdifferentiation) expression as compared to controls. Experiments to investigate mechanisms through which Oct4 might regulate transdifferentiation are under way.