Project description:Stem/progenitor cells represent an unlimited cell source for the generation of hepatocytes. As such, it was already shown that the hepatic liver progenitor-like cell line rLEC acquires a hepatocyte-like phenotype upon sequential exposure to hepatic growth factors and cytokines. However, expression of hepatocyte nuclear factor (HNF) 4α is still missing, hampering their full differentiation. Therefore, we aim at studying the phenotype of rLEC by transducing the cells with HNF4α. In addition, to make the genes more sensitive to transcription and differentiation, the effect of the DNA methyl transferase inhibitor 5' azacytidine (AZA) (20 µM) was also investigated. The global expression profiles of both microRNA and mRNA were studied by means of microarray technology. Overall design: rLEC were transduced with a viral vector containing HNF4α and puromycin selected. In addition, cells were exposed to 20µM 5'azacytidine for 7 days
Project description:Neonatal liver-derived rat epithelial cells (rLEC) from biliary origin are liver progenitor cells that acquire a hepatocyte-like phenotype upon sequential exposure to hepatogenic growth factors and cytokines. Undifferentiated rLEC express several liver-enriched transcription factors, including the hepatocyte nuclear factors (HNF) 3? and HNF6, but not the hepatic master regulator HNF4?. In this study, we first investigated the impact of the ectopic expression of HNF4? in rLEC on both mRNA and microRNA (miR) level by means of microarray technology. We found that HNF4? transduction did not induce major changes to the rLEC phenotype. However, we next investigated the influence of DNA methyl transferase (DNMT) inhibition on the phenotype of undifferentiated naïve rLEC by exposure to 5' azacytidine (AZA), which was found to have a significant impact on rLEC gene expression. The transduction of HNF4? or AZA treatment resulted both in significantly downregulated C/EBP? expression levels, while the exposure of the cells to AZA had a significant effect on the expression of HNF3?. Computationally, dysregulated miRNAs were linked to target mRNAs using the microRNA Target Filter function of Ingenuity Pathway Analysis. We found that differentially regulated miRNA-mRNA target associations predict ectopic HNF4? expression in naïve rLEC to interfere with cell viability and cellular maturation (miR-19b-3p/NR4A2, miR30C-5p/P4HA2, miR328-3p/CD44) while it predicts AZA exposure to modulate epithelial/hepatic cell proliferation, apoptosis, cell cycle progression and the differentiation of stem cells (miR-18a-5p/ESR1, miR-503-5p/CCND1). Finally, our computational analysis predicts that the combination of HNF4? transduction with subsequent AZA treatment might cause changes in hepatic cell proliferation and maturation (miR-18a-5p/ESR1, miR-503-5p/CCND1, miR-328-3p/CD44) as well as the apoptosis (miR-16-5p/BCL2, miR-17-5p/BCL2, miR-34a-5p/BCL2 and miR-494-3p/HMOX1) of naïve rLEC.
Project description:Hepatocyte-like cells from human embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) are expected to be a useful source of cells drug discovery. Although we recently reported that hepatic commitment is promoted by transduction of SOX17 and HEX into human ESC- and iPSC-derived cells, these hepatocyte-like cells were not sufficiently mature for drug screening. To promote hepatic maturation, we utilized transduction of the hepatocyte nuclear factor 4α (HNF4α) gene, which is known as a master regulator of liver-specific gene expression. Adenovirus vector-mediated overexpression of HNF4α in hepatoblasts induced by SOX17 and HEX transduction led to upregulation of epithelial and mature hepatic markers such as cytochrome P450 (CYP) enzymes, and promoted hepatic maturation by activating the mesenchymal-to-epithelial transition (MET). Thus HNF4α might play an important role in the hepatic differentiation from human ESC-derived hepatoblasts by activating the MET. Furthermore, the hepatocyte like-cells could catalyze the toxication of several compounds. Our method would be a valuable tool for the efficient generation of functional hepatocytes derived from human ESCs and iPSCs, and the hepatocyte-like cells could be used for predicting drug toxicity.
Project description:Although they are expandable in vitro, hepatic progenitors are immature cells and share many immunomarkers with hepatocellular carcinoma, raising potential concerns regarding maltransformation after transplantation. This study investigated the effects of hepatic nuclear factor (HNF) 4α on the proliferation, migration, and maltransformation of hepatic progenitors and determined the feasibility of using these manipulated cells for transplantation.The effects of HNF4α on rat hepatic progenitors (i.e. hepatic oval cells) were analyzed by HNF4α overexpression and HNF4α shRNA. Nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice injured by carbon chloride (CCl4) were then transplanted with control, HNF4α-overexpressing or HNF4α-suppressing hepatic oval cells. Finally, the engraftment of these cells in the recipient liver was analyzed.Rat hepatic progenitors (i.e. hepatic oval cells) expressed HNF4α, although less than that in hepatocytes. When HNF4α was overexpressed in these cells, the proliferation and migration of hepatic oval cells were reduced; but when HNF4α was suppressed by shRNA, the proliferation and migration, and even anchorage-independent growth, of these cells were accelerated. RNA microarray and gene functional analysis revealed that suppressing HNF4α not only impaired many biosynthesis and metabolism pathways of hepatocytes but also increased pathways for cancer. When transplanted into CCl4-injured NOD/SCID mice, few HNF4α-suppressing hepatic oval cells localized into the liver, while control cells and HNF4α-overexpressing cells engrafted into the liver and differentiated into albumin-positive hepatocytes. Interestingly, the hepatocytes derived from HNF4α-overexpressing cells were less migrative and expressed less c-Myc than the cells derived from control cells.HNF4α constrains proliferation, migration, and maltransformation of hepatic progenitors, and HNF4α-overexpressing hepatic progenitors serve as an optimal candidate for cell transplantation.
Project description:To investigate the effect of hepatocyte nuclear factor 4α (HNF4α) on the differentiation and transformation of hepatic stellate cells (HSCs).By constructing the recombinant adenovirus vector expressing HNF4α and HNF4α shRNA vector, and manipulating HNF4α expression in HSC-T6 cells, we explored the influence of HNF4α and its induction capacity in the differentiation of rat HSCs into hepatocytes.With increased expression of HNF4α mediated by AdHNF4α, the relative expression of Nanog was downregulated in HSC-T6 cells (98.33 ± 12.33 vs 41.33 ± 5.67, P < 0.001). Consequently, the expression of G-P-6 and PEPCK was upregulated (G-P-6: 14.34 ± 3.33 vs 42.53 ± 5.87, P < 0.01; PEPCK: 10.10 ± 4.67 vs 56.56 ± 5.25, P < 0.001), the expression of AFP and ALB was positive, and the expression of Nanog, Type I collagen, α-SMA, and TIMP-1 was significantly decreased. HNF4α also downregulated vimentin expression and enhanced E-cadherin expression. The ultrastructure of HNF4α-induced cells had more mitochondria and ribosomes compared with the parental cells. After silencing HNF4α expression, EPCK, E-cadherin, AFP, and ALB were downregulated and α-SMA and vimentin were upregulated.HNF4α can induce a tendency of differentiation of HSCs into hepatocyte-like cells. These findings may provide an effective way for the treatment of liver diseases.
Project description:Liver-enriched transcription factors (LETF) play a crucial role in the control of liver-specific gene expression and for hepatocytes to retain their molecular and cellular functions complex interactions with extra cellular matrix (ECM) are required However, during cell isolation ECM interactions are disrupted and for hepatocytes to regain metabolic competency cells are cultured on ECM substrata. The regulation of LETFs in hepatocytes cultured on different ECM has not been studied in detail. We therefore compared two common sources of ECM and evaluated cellular morphology and hepatocyte differentiation by investigating DNA binding activity of LETFs at gene specific promoters and marker genes of hepatic metabolism. Furthermore, we studied testosterone metabolism and albumin synthesis to assess the metabolic competence of cell cultures. Despite significant difference in morphological appearance and except for HNF1β (p<0.001) most LETFs and several of their target genes did not differ in transcript expression after Bonferroni adjustment when cultured on collagen or Matrigel. Nonetheless, Western blotting revealed HNF1β, HNF3α, HNF3γ, HNF4α, HNF6 and the smaller subunits of C/EBPα and C/EBPβ to be more abundant on Matrigel cultured cells. Likewise, DNA binding activity of HNF3α, HNF3β, HNF4α, HNF6 and gene expression of hepatic lineage markers were increased on Matrigel cultured hepatocytes. To further investigate hepatic gene regulation, the effects of Aroclor 1254 treatment, e.g. a potent inducer of xenobiotic defense were studied in vivo and in vitro. The gene expression of C/EBP-α increased in rat liver and hepatocytes cultured on collagen and this treatment induced DNA binding activity of HNF4α, C/EBPα and C/EBPβ and gene expression of CYP1A1 and CYP1A2 in vivo and in vitro. Taken collectively, two sources of ECM greatly affected hepatocyte morphology, activity of liver enriched transcription factors, hepatic gene expression and metabolic competency that should be considered when used in cell biology studies and drug toxicity testing.
Project description:Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), chemicals present in a multitude of consumer products, are persistent organic pollutants. Both compounds induce hepatotoxic effects in rodents, including steatosis, hepatomegaly and liver cancer. The mechanisms of PFOA- and PFOS-induced hepatic dysfunction are not completely understood. We present evidence that PFOA and PFOS induce their hepatic effects via targeting hepatocyte nuclear factor 4-alpha (HNF4α). Human hepatocytes treated with PFOA and PFOS at a concentration relevant to occupational exposure caused a decrease in HNF4α protein without affecting HNF4α mRNA or causing cell death. RNA sequencing analysis combined with Ingenuity Pathway Analysis of global gene expression changes in human hepatocytes treated with PFOA or PFOS indicated alterations in the expression of genes involved in lipid metabolism and tumorigenesis, several of which are regulated by HNF4α. Further investigation of specific HNF4α target gene expression revealed that PFOA and PFOS could promote cellular dedifferentiation and increase cell proliferation by down regulating positive targets (differentiation genes such as CYP7A1) and inducing negative targets of HNF4α (pro-mitogenic genes such as CCND1). Furthermore, in silico docking simulations indicated that PFOA and PFOS could directly interact with HNF4α in a similar manner to endogenous fatty acids. Collectively, these results highlight HNF4α degradation as novel mechanism of PFOA and PFOS-mediated steatosis and tumorigenesis in human livers.
Project description:BACKGROUND:MicroRNA-21 (miR-21) plays an important role in the pathogenesis and progression of liver fibrosis. Here, we determined the serum and hepatic content of miR-21 in patients with liver cirrhosis and rats with dimethylnitrosamine-induced hepatic cirrhosis and examined the effects of miR-21 on SPRY2 and HNF4α in modulating ERK1 signaling in hepatic stellate cells (HSCs) and epithelial-mesenchymal transition (EMT) of hepatocytes. METHODS:Quantitative RT-PCR was used to determine miR-21 and the expression of SPRY2, HNF4α and other genes. Immunoblotting assay was carried out to examine the expression of relevant proteins. Luciferase reporter assay was performed to assess the effects of miR-21 on its predicted target genes SPRY2 and HNF4α. Primary HSCs and hepatocytes were treated with miR-21 mimics/inhibitors or appropriate adenoviral vectors to examine the relation between miR-21 and SPRY2 or HNF4α. RESULTS:The serum and hepatic content of miR-21 was significantly higher in cirrhotic patients and rats. SPRY2 and HNF4α mRNA levels were markedly lower in the cirrhotic liver. MiR-21 overexpression was associated with enhanced ERK1 signaling and EMT in liver fibrosis. Luciferase assay revealed suppressed SPRY2 and HNF4α expression by miR-21. Ectopic miR-21 stimulated ERK1 signaling in HSCs and induced hepatocyte EMT by targeting SPRY2 or HNF4α. Downregulating miR-21 suppressed ERK1 signaling, inhibited HSC activation, and blocked EMT in TGFβ1-treated hepatocytes. CONCLUSIONS:MiR-21 modulates ERK1 signaling and EMT in liver fibrosis by regulating SPRY2 and HNF4α expression. MiR-21 may serve as a potentially biomarker as well as intervention target for hepatic cirrhosis.
Project description:In the liver Wnt-signaling contributes to the metabolic fate of hepatocytes, but the precise role of the TCF7L2 in this process is unknown. We employed a temporal RNA-Seq approach to examine gene expression 3-96 h following Tcf7l2 silencing in rat hepatoma cells, and combined this with ChIP-Seq to investigate mechanisms of target gene regulation by TCF7L2. Silencing Tcf7l2 led to a time-dependent appearance of 406 differentially expressed genes (DEGs), including key regulators of cellular growth and differentiation, and amino acid, lipid and glucose metabolism. Direct regulation of 149 DEGs was suggested by strong proximal TCF7L2 binding (peak proximity score > 10) and early mRNA expression changes (≤ 18 h). Indirect gene regulation by TCF7L2 likely occurred via alternate transcription factors, including Hnf4a, Foxo1, Cited2, Myc and Lef1, which were differentially expressed following Tcf7l2 knock-down. Tcf7l2-silencing enhanced the expression and chromatin occupancy of HNF4α, and co-siRNA experiments revealed that HNF4α was required for the regulation of a subset of metabolic genes by TCF7L2, particularly those involved in lipid and amino-acid metabolism. Our findings suggest TCF7L2 is an important regulator of the hepatic phenotype, and highlight novel mechanisms of gene regulation by TCF7L2 that involve interplay between multiple hepatic transcriptional pathways.
Project description:To uncover the role of hepatocyte nuclear factor 4 alpha (HNF4α) in regulating hepatic expression of microRNAs.Microarray and real-time PCR were used to determine hepatic expression of microRNAs in young-adult mice lacking Hnf4α expression in liver (Hnf4α-LivKO). Integrative genomics viewer software was used to analyze the public chromatin immunoprecipitation-sequencing datasets for DNA-binding of HNF4α, RNA polymerase-II, and histone modifications to loci of microRNAs in mouse liver and human hepatoma cells. Dual-luciferase reporter assay was conducted to determine effects of HNF4α on the promoters of mouse and human microRNAs as well as effects of microRNAs on the untranslated regions (3'UTR) of two genes in human hepatoma cells.Microarray data indicated that most microRNAs remained unaltered by Hnf4α deficiency in Hnf4α-LivKO mice. However, certain liver-predominant microRNAs were down-regulated similarly in young-adult male and female Hnf4α-LivKO mice. The down-regulation of miR-101, miR-192, miR-193a, miR-194, miR-215, miR-802, and miR-122 as well as induction of miR-34 and miR-29 in male Hnf4α-LivKO mice were confirmed by real-time PCR. Analysis of public chromatin immunoprecipitation-sequencing data indicates that HNF4α directly binds to the promoters of miR-101, miR-122, miR-194-2/miR-192 and miR-193, which is associated with histone marks of active transcription. Luciferase reporter assay showed that HNF4α markedly activated the promoters of mouse and human miR-101b/miR-101-2 and the miR-194/miR-192 cluster. Additionally, miR-192 and miR-194 significantly decreased activities of luciferase reporters for the 3'UTR of histone H3F3 and chromodomain helicase DNA binding protein 1 (CHD1), respectively, suggesting that miR-192 and miR-194 might be important in chromosome remodeling through directly targeting H3F3 and CHD1.HNF4α is essential for hepatic basal expression of a group of liver-enriched microRNAs, including miR-101, miR-192, miR-193a, miR-194 and miR-802, through which HNF4α may play a major role in the post-transcriptional regulation of gene expression and maintenance of the epigenome in liver.