Project description:Expression profiling of hepatocytes-derived ductal cells with properties intermediate between mature hepatocytes and cholangiocytes. Chimeric adult mice were generated where mature hepatocytes were marked with a fluorescent red marker. Chronic injury was induced for ~6weeks and three cell types were isolated by FACS (Influx, BD) for expression analysis by RNAseq based on cell surface phenotype and origin: hepatocytes (n=3), hepatocyte-derived oval cells (1c3+, n=5), and cholangiocyte-derived oval cells (1c3+, n=5).
Project description:Liver possesses robust regenerative ability, characterized by flexibility in the cellular source of regeneration based on the extent of the injury. After partial hepatectomy or minor injuries, hepatocytes, the primary liver cells, undergo self-duplication to replenish the liver mass. In contrast, when the damage is extensive, or hepatocyte proliferation is impaired, cholangiocytes contribute to hepatocyte recovery. This current paradigm of regenerative flexibility in the liver has been established for animals with little or no growth. However, the regenerative mechanisms during periods of growth in young animals remain unexplored. Here, we establish two new partial liver injury protocols in the zebrafish model of rapid growth during late larval stage and observe emergence of de novo hepatocytes in the presence of spared hepatocytes. Using single-cell RNA sequencing and lineage tracing, we identify cholangiocytes as the source of de novo hepatocytes. Our study offers a new perspective on the current paradigm of liver regenerating by proposing cholangiocyte-to-hepatocyte transdifferentiation as the default mechanism of hepatocyte recovery in late larval stage zebrafish.
Project description:The goal of this experiment was to test whether human hepatocytes could give rise to biliary-like progenitor cells in an in vivo context. Here Fah-/- Il2ry-/- Rag2-/-NOD mouse livers were humanized with human hepatocytes. Only hepatocytes engraft in the Fah-/- mouse at detectable levels in this model. Then animals were given chronic liver injury with 0.1% ddc. After injury we measured human-specific transcripts to determine whether the phenotype of the human cells had changed. Specifically, we evaluated the relative levels of human biliary duct markers such as Spp1, Sox9, Krt7, etc. and hepatocyte markers such as Alb, Ttr, Fah, etc. 3 DDC treated chimeras and 6 untreated chimeras are included. Additional controls include a normal human liver biopsy, FACS sorted primary intrahepatic human bile duct cells, mouse hepatocytes, and mouse intrahepatic biliary cells in ddc treated animal.
Project description:PR-SET7-mediated histone-4 lysine-20 methylation has been implicated in mitotic condensation, DNA damage response and replication licencing. Here we show that PR-SET7 function in the liver is pivotal for maintaining genome integrity. Hepatocyte-specific deletion of PR-SET7 in mouse embryos resulted in G2 arrest followed by massive cell death and defect in liver organogenesis. Inactivation at postnatal stages caused cell duplication-dependent hepatocyte necrosis with unusual features of autophagy, termed "endonucleosis". Necrotic death was accompanied by inflammation, fibrosis and compensatory growth induction of neighboring hepatocytes and resident ductal progenitor cells. Prolonged necrotic-regenerative cycles coupled with oncogenic STAT3 activation replaced pre-existing hepatocytes with hepatocellular carcinoma derived entirely from ductal progenitor cells. Hepatocellular carcinoma in these mice displays a cancer stem cell gene signature specified by the co-expression of ductal progenitor markers and oncofetal genes. Mice carrying hepatocyte specific inactivation of PR-SET7 were generated in order to investigate the function of PR-SET7 histone methyl transferase in liver organogenesis, hepatocyte proliferation and liver regeneration. P15 WT mice were injected intra-peritoneally (ip) with 25ml per kg DEN (diethyl nitrosamine). Mice were examined for RNA expression at 8 months old.
Project description:We observed de novo formation of peripheral bile ducts by transdifferentiation of hepatocytes in mice born without peripheral bile ducts. To assess the authenticity and maturity of the hepatocyte-derived peripheral cholangiocytes forming the new bile ducts, we compared their global gene expression profile to that of peripheral cholangiocytes isolated from normal mice. We also included hepatocytes isolated from mice born without peripheral bile ducts as a control.
Project description:PR-SET7-mediated histone-4 lysine-20 methylation has been implicated in mitotic condensation, DNA damage response and replication licencing. Here we show that PR-SET7 function in the liver is pivotal for maintaining genome integrity. Hepatocyte-specific deletion of PR-SET7 in mouse embryos resulted in G2 arrest followed by massive cell death and defect in liver organogenesis. Inactivation at postnatal stages caused cell duplication-dependent hepatocyte necrosis with unusual features of autophagy, termed "endonucleosis". Necrotic death was accompanied by inflammation, fibrosis and compensatory growth induction of neighboring hepatocytes and resident ductal progenitor cells. Prolonged necrotic-regenerative cycles coupled with oncogenic STAT3 activation replaced pre-existing hepatocytes with hepatocellular carcinoma derived entirely from ductal progenitor cells. Hepatocellular carcinoma in these mice displays a cancer stem cell gene signature specified by the co-expression of ductal progenitor markers and oncofetal genes.
Project description:Acinar ductal metaplasia (ADM), is believed to be one of the earliest precursor lesions towards the development of pancreatic ductal adenocarcinoma, and maintaining the pancreatic acinar cell phenotype suppresses tumor formation. We report that pStat3 and HDAC inhibition can attenuate ADM in vitro and TSA treatment reverses the dedifferentiated phenotype to one that is more acinar. Our findings suggest that pharmacological inhibition or reversal of pancreatic ADM represents a potential therapeutic strategy for blocking ductal reprogramming of acinar cells.
Project description:Background and aims: Signal transducer and activator of transcription 3 (Stat3) is the main mediator of interleukin-6 type cytokine signaling required for hepatocyte proliferation and hepatoprotection but its role in sclerosing cholangitis and other cholestatic liver diseases remains unresolved. Methods: We investigated the role of Stat3 in inflammation-induced cholestatic liver injury and used mice lacking the multidrug resistance gene 2 (mdr2-/-) as a model for SC. Results: We demonstrate that conditional inactivation of stat3 in hepatocytes and cholangiocytes (stat3 delta hc) of mdr2-/- mice strongly aggravated bile acid-induced liver injury and fibrosis. A similar phenotype was observed in mdr2-/- mice lacking IL-6 production. Biochemical and molecular characterization suggested that Stat3 exerts hepatoprotective functions in both, hepatocytes and cholangiocytes. Loss of Stat3 in cholangiocytes led to increased expression of TNFα which might reduce the barrier function of bile ducts. Loss of Stat3 in hepatocytes led to upregulation of bile acid biosynthesis genes and downregulation of hepatoprotective epidermal growth factor receptor and insulin-like growth factor 1 signaling pathways. Consistently, stat3deltahc mice were more sensitive to cholic acid-induced liver damage than control mice. Conclusions: Our data suggest that Stat3 prevents cholestasis and liver damage in sclerosing cholangitis via regulation of pivotal functions in hepatocytes and cholangiocytes. Affymetrix microarray analyses was performed to identify metabolic and molecular pathways in stat3Dhc mdr2-/- mice that lead to cholestasis and bile acid-induced liver injury. To avoid false positive results that are due to differential cellular composition, we defined the onset of fibrosis and expression of fibrogenic factors in stat3Dhc mdr2-/- mice.
Project description:The goal of this experiment was to test whether human hepatocytes could give rise to biliary-like progenitor cells in an in vivo context. Here Fah-/- Il2ry-/- Rag2-/-NOD mouse livers were humanized with human hepatocytes. Only hepatocytes engraft in the Fah-/- mouse at detectable levels in this model. Then animals were given chronic liver injury with 0.1% ddc. After injury we measured human-specific transcripts to determine whether the phenotype of the human cells had changed. Specifically, we evaluated the relative levels of human biliary duct markers such as Spp1, Sox9, Krt7, etc. and hepatocyte markers such as Alb, Ttr, Fah, etc.
Project description:Hepatocytes undergo the metaplasia into ductal biliary epithelial cells (BECs) in response to chronic injury, and subsequently contribute to liver regeneration. The mechanism underlying hepatocyte-to-ductal metaplasia has not been explored until now. In mouse models of liver fibrosis, a florid BEC response was observed in fibrotic liver, and the depletion of myofibroblasts attenuated BEC expansion remarkably. Then, in hepatocyte fate-tracing mouse model, we demonstrated the conversion of mature hepatocytes into ductal BECs in fibrotic liver, and the depletion of myofibroblasts diminished the hepatocyte-to-ductal metaplasia. Finally, the mechanism underlying the metaplasia was investigated. Myofibroblasts secreted laminin-rich extracellular matrix, and then laminin induced hepatocyte-to-ductal metaplasia through ?v?6 integrin. Therefore, our results demonstrated myofibroblasts induce the conversion of mature hepatocytes into ductal BECs through laminin-?v?6 integrin, which reveals that the strategy improve regeneration in fibrotic liver through the modification of specific microenvironment.