THE BILIARY EPITHELIUM GIVES RISE TO LIVER PROGENITOR CELLS BUT MAKES A MINOR CONTRIBUTION TO HEPATOCYTE REGENERATION AFTER LIVER INJURY
ABSTRACT: We previously showed that severe liver diseases are characterized by expansion of liver progenitor cells (LPC), which correlates with disease severity. However, the origin and role of LPC in liver physiology and in the hepatic response to injury remains a contentious topic. We have now used genetic lineage tracing of Hnf1β-expressing biliary duct cells to assess their contribution to LPC expansion and hepatocyte generation during normal liver homeostasis, and following different types of liver injury. We found that ductular reaction cells in human cirrhotic livers express HNF1β. However, HNF1β expression was not present in newly generated EpCAM-positive hepatocytes. Using a tamoxifen-inducible Hnf1βCreER/R26RYFP/LacZ mouse, we show that there is no contribution of the biliary epithelium to hepatocyte turnover during liver homeostasis in healthy mice. Moreover, after loss of liver mass, Hnf1β+ LPC did not contribute to hepatocyte regeneration. We also assessed the contribution of Hnf1β+ cells following acute and repeated liver injury. All animal models showed expansion of LPC, as assessed by immunostaining and gene expression profile of sorted YFP-positive cells. A contribution of Hnf1β+ LPC to hepatocyte generation was not detected in animal models of liver injury with preserved hepatocyte regenerative potential such as acute acetaminophen, carbon tetrachloride injury, or chronic diethoxycarbonyl-1,4-dihydro-collidin (DDC)-diet. However, in mice fed with choline-deficient ethionine-supplemented (CDE)-diet, which causes profound hepatocyte damage and arrest, a small number of hepatocytes were derived from Hnf1β+ cells. Conclusion: Hnf1β+ cells do not participate in hepatocyte turnover in the healthy liver or during liver regeneration after partial hepatectomy. After liver injury, LPC arise from the biliary duct epithelium, which gives rise to a limited number of hepatocytes only when hepatocyte regeneration is compromised. Transcriptomic profile using MoGeneST-2.0 chip from 3 samples of YFP+ CDE, 3 samples of YFP+ DDC, 2 samples of YFP+ UTR and 3 samples YFP-
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:For years, the term apoptosis was used synonymously for programmed cell death. However, it was recently discovered that programmed necrosis – dependent on the kinases Receptor-Interacting-Protein-Kinase (RIP)1 and RIP3 (also called necroptosis) – represents a major programmed cell-death pathway in development and immunity. At present, the functions of necroptosis in hepatitis, liver cancer development and biliary disease are unclear. Here we show that in mice with chronic hepatitis due to conditional ablation of TGF-beta-activated kinase1 (TAK1) in liver parenchymal cells (LPC), both apoptotic and necroptotic signaling pathways are activated. Strikingly, only Caspase-8-dependent apoptosis promotes spontaneous liver cancer development, while in contrast LPC necroptosis inhibits hepatic tumourigenesis. The tumour-promoting effect of apoptosis results from an induction of strong compensatory proliferation of LPC, linked with the paracrine action of growth factors like Insulin-like growth factor-2 (IGF-2) not induced by necroptosis. In addition to prevention of HCC development, induction of necroptosis leads to massive cholestasis and hyperbilirubinemia, resulting from an insufficient ductular reaction and biliary regeneration from the hepatic stem cell niche as a response to chronic hepatitis. These results indicate previously undefined distinctive functions of apoptosis and programmed necrosis in controlling cancer development and cholestasis in the liver with important implications for future therapeutic strategies in chronic liver disease. 8 samples were analysed. We compared groups of 4 Tak1/Caspase8 LPC double knockout mice and 4 Tak1 LPC-KO/Rip3-/- mice to detect genes differentially regulated by apoptotic and necrotic signalling pathways.
Project description:The winged helix transcription factor Foxl1 is a marker for progenitor cells and their descendants in the mouse liver in vivo. Here, we purify progenitor cells from Foxl1-Cre; RosaYFP mice and evaluate their proliferative and differentiation potential in vitro. Treatment of Foxl1-Cre; RosaYFP mice with 3,5-diethoxycarbonyl-1,4-dihydrocollidine diet led to an increase of the percentage of YFP-labeled Foxl1+ cells. Clonogenic assays demonstrated that up to 3.6% of Foxl1+ cells had proliferative potential. Foxl1+ cells differentiated into cholangiocytes and into hepatocytes in vitro, depending on the culture condition employed. Microarray analyses indicated that Foxl1+ cells express stem cell markers such as Prom1 as well as differentiation markers such as Ck19 and Hnf4a. Thus, the Foxl1-Cre; RosaYFP model allows for easy isolation of adult hepatic progenitor cells that can be expanded and differentiated in culture. There were 26 samples used in the analysis. Typically 4 replicates for each of 7 conditions, except for two condtions which had only 3 replicates. Day 0 samples are non-parenchymal cells without DDC treatment. YFP_pos samples are YFP-expressing non-parenchymal cells induced by Foxl1-CRE after 3, 7 or 14 days of DDC treatment. YFP_neg samples are analogous but do not expressed YFP.
Project description:Cells with slow proliferation kinetics that retain the nuclear label over long time periods – the label-retaining cells (LRCs) – represent multipotent stem cells in a number of adult tissues. Since the identity of liver LRCs (LLRCs) had remained elusive we utilized a genetic approach to reveal LLRCs in normal non-injured livers and characterized their regenerative properties in vivo and in culture. We found that LLRCs were located in biliary vessels and participated in the regeneration of biliary but not hepatocyte injury. In culture experiments the sorted LLRCs displayed an enhanced self-renewal capacity but a unipotent biliary differentiation potential. Transcriptome analysis revealed a unique set of tumorigenesis- and nervous system-related genes upregulated in LLRCs when compared to non-LRC cholangiocytes. We conclude that the LLRCs established during the normal morphogenesis of the liver do not represent a multipotent primitive somatic stem cell population but act as unipotent biliary progenitor cells. Overall design: Transcriptome comparison of label-retaining biliary epithelial cells and non-label-retaining biliary epithelial cells (cells with GFP expression were compared to the cells without GFP). Illumina HiSeq 2000 was used to analyze 8 RNA samples from 4 mice.
Project description:Hepatoblasts emerging at E8.5 from the foregut endoderm proliferate vigorously and differentiate to hepatocytes and biliary epithelial cells. To find genes important for hepatocyte differentiation during development, we compared gene expression profiles of hepatoblasts/immature hepatocytes at E12.5 and E17.5. As Dlk, also known as Pref-1, is expressed in hepatoblasts/immature hepatocytes, we performed a microarray analysis of the Dlk+ cells isolated from livers at E12.5 and E17.5. Keywords: fetal liver cells comparing Mouse hepatoblasts were isolated from E12.5 and E17.5 fetal liver using anti-mouse Dlk monoclonal antibody (mAb) according to a previous report and dissolved in Trizol reagent. The cDNA samples synthesized from total RNA were used for a microarray analysis with the mouse GEM2 microarray. One array, no replicates.
Project description:Animal models of parenchymal liver injury by bile duct ligation (BDL) and all forms of liver diseases including neonatal hepatitis and clinical obstructive cholangiopathies such as biliary atresia have the pathological features of cholestasis and liver dysfunction. Hepatocyte nuclear factors 6 (HNF6) is important to the transcriptional regulation, expression and function of essential hepatic genes involved in the differentiated as well as the adaptive response to liver injury. Using HNF6 conditional knock out mice where HNF6 is functionally deleted in the liver, we established that HNF6 is required for proper liver function of cholesterol clearance, improvement of cholestasis and hepatocyte regeneration. Enhancing HNF6 expression in wild type mice also diminished hepatic apoptosis and fibrosis. In this proposal, we propose to further characterize the biological function of HNF6 by testing the HYPOTHESIS that HNF6 direct transcriptional regulation of antiapoptotic and antifibrotic pathways contributes to hepatoprotection during bile duct injury. This hypothesis will be tested in two specific aims. Overall design: Livers were isolated from wild-type (WT) and HNF6 knockout (KO) mice respectively. Liver samples were processed via ChIP protocol using monoclonal HNF6 or IgG antibodies (control). ChIP-DNA was further processed by Affymetrix Procedure H. The following samples are PCR products: (1) wild-type liver 1 & HNF6 antibody; (2) wild-type liver 2 & HNF6 antibody; (3) wild-type liver 1 & IgG antibody; (4) wild-type liver 2 & IgG antibody; (5) HNF6-knockout liver 1 & HNF6 antibody; (6) HNF6-knockout liver 1 & HNF6 antibody.
Project description:S23 experiment: We sought to identify the microRNAs (miRNAs) enriched in the neural crest cell (NCC) population from E11.5 mouse embryos. To accomplish this, we utilized a transgenic mouse line harboring Cre-recombinase under the control of the Wnt1 NCC-specific promoter and also carrying the R26R-YFP allele. We sorted YFP+ (NCCs) and YFP- (non-NCCs) from E11.5 Wnt1Cre-R26R mouse embryos via FACS and compared the relative enrichment of miRNAs in the YFP+ population by miRNA microarray. 220 experiment: We sought to identify the microRNAs (miRNAs) enriched in the neural crest cell (NCC) population from E10.5 mouse embryos. To accomplish this, we utilized a transgenic mouse line harboring Cre-recombinase under the control of the Wnt1 NCC-specific promoter and also carrying the R26R-YFP allele. We sorted YFP+ (NCCs) and YFP- (non-NCCs) from E10.5 Wnt1Cre-R26R mouse embryos via FACS and compared the relative enrichment of miRNAs in the YFP+ population by miRNA microarray. 221 experiment: Our research has shown that heterozygous deletion of the miRNA processing enzyme Dicer leads to developmental delay of the thymus in mouse embryos. We sought to identify the microRNAs (miRNAs) affected by the loss of a single copy of Dicer in the neural crest cell (NCC) population from E10.5 mouse embryos. To accomplish this, we utilized a transgenic mouse line harboring a floxed allele of Dicer, Cre-recombinase under the control of the Wnt1 NCC-specific promoter, and also carrying the R26R-YFP allele. We sorted YFP+ (NCCs) cells from E10.5 Dicerfl/+,Wnt1Cre,R26R and Dicer+/+,Wnt1Cre,R26R mouse embryos via FACS and compared the relative expression of miRNAs in the Dicer-heterozygotes compared to Dicer-wildtypes by miRNA microarray. S23 experiment: RNA from YFP+ (NCCs) and YFP- (non-NCCs) cells sorted by FACS from E11.5 Wnt1Cre-R26R mouse embryos was isolated and hybridized to Exiqon miRNA microarrays v10. Cells from five E11.5 embryos were sorted into YFP+ and YFP- populations and pooled. 220 experiment: RNA from YFP+ (NCCs) and YFP- (non-NCCs) cells sorted by FACS from E10.5 Wnt1Cre-R26R mouse embryos was isolated and hybridized to Exiqon miRNA microarrays v10. Cells from ten E10.5 embryos were sorted into YFP+ and YFP- populations and pooled. 221 experiment: RNA from YFP+ (NCCs) cells sorted by FACS from E10.5 Dicerfl/+,Wnt1Cre,R26R and Dicer+/+,Wnt1Cre,R26R mouse embryos was isolated and hybridized to Exiqon miRNA microarrays v10. Cells from ten embryos were sorted into YFP+ populations and pooled for each genotype.
Project description:A "Cartes d'Identite des Tumeurs" (CIT) project from the french Ligue Nationale Contre le Cancer (http://cit.ligue-cancer.net). This work aims to demonstrate a key role for the Wnt/beta-catenin pathway in liver embryonic growth and in controlling the fate of hepatoblasts, preventing them to differentiate towards the hepatocyte lineage, and guiding them to a duct morphogenesis. Through the inactivation of Apc (adenomatous Polyposis Coli) tumor suppressor gene in hepatoblasts by a Cre-loxP strategy, the ectopic activation of beta-catenin targeted in hepatoblasts after liver bud formation leads to a lethal embryonic phenotype, characterized by liver hypoplasia, a blockade of hepatocyte differentiation and commitment to a biliary fate. (this work was supported by INSERM and the BLigue Nationale
Project description:Death receptor-mediated hepatocyte apoptosis is implicated in a wide range of liver diseases including viral hepatitis, alcoholic hepatitis, ischemia/reperfusion injury, fulminant hepatic failure, cholestatic liver injury and cancer. Deletion of NF-ĸB essential modulator in hepatocytes (NemoΔhepa) causes the spontaneous development of hepatocellular carcinoma preceded by steatohepatitis in mice and thus serves as an excellent model for the progression from chronic hepatitis to liver cancer. In the present study we aimed to dissect the death-receptor mediated pathways that contribute to liver injury in NemoΔhepa mice. Therefore, we generated NemoΔhepa/TRAIL-/- and NemoΔhepa/TNFR1-/- animals and analyzed the progression of liver injury. NemoΔhepa/TRAIL-/- displayed a similar phenotype to NemoΔhepa mice characteristic of high apoptosis, infiltration of immune cells, hepatocyte proliferation and steatohepatitis. These pathophysiological features were significantly ameliorated in NemoΔhepa/TNFR1-/- livers. Hepatocyte apoptosis was increased in NemoΔhepa and NemoΔhepa/TRAIL-/- mice while NemoΔhepa/TNFR1-/- animals showed reduced cell death concomitant with a strong reduction in pJNK levels. Cell cycle parameters were significantly less activated in NemoΔhepa/TNFR1-/- livers. Additionally, markers of liver fibrosis and indicators of tumour progression were significantly decreased in these animals. The present data demonstrate that the death receptor TNFR1 but not TRAIL is important in determining progression of liver injury in hepatocyte-specific Nemo knockout mice. Expression profiling of livers from wild type, NEMO, NEMO-TRIAL, and NEMO-TNFR null mice
Project description:Abelson virus (v-Abl)-transformed pre-B cell lines from BM of dcrfl/fl; R26R-yfp (4470; 4475) and dcrfl/+; R26R-yfp mice (4483) are treated with a transducible Cre protein (Tat-Cre) to induce deletion of the dicer-1 gene in vitro. Cre activity is conveniently monitored by concomitant expression of YFP. To obtain Dicer KO cells, YFP+ cells from dcrfl/fl; R26R-yfp (4470_YFP; 4475_YFP) cultures treated with Tat-cre were isolated by fluorescence-activated cell sorting (FACS) and further propagated in cell culture. As controls, we used non-deleted, YFP- cells sorted from dcrfl/fl; R26R-yfp cultures (4470; 4475) treated with Tat-cre, and YFP+ deleted cells from dcrfl/+; R26R-yfp cultures (4483_YFP). To validate this system, various cell populations were sorted and analyzed for Dicer protein and miRNA expression. In the Dicer KO pro-B cell lines, Western analysis indicated that Dicer protein was efficiently ablated, and Northern blots demonstrated that the levels of mature miR-17 and miR-191 were drastically reduced.