Project description:The recovery of liver mass is mainly mediated by proliferation and enlargement of hepatocytes after partial hepatectomy. Studying the gene expression profiles of hepatocytes after partial hepatectomy will be helpful in exploring the mechanism of liver regeneration. We used microarrays to further highlight the regulatory role of hepatocyte in liver regeneration at gene transcription level.
Project description:The recovery of liver mass is mainly mediated by proliferation and enlargement of hepatocytes after partial hepatectomy. Studying the gene expression profiles of hepatocytes after partial hepatectomy will be helpful in exploring the mechanism of liver regeneration. We used microarrays to further highlight the regulatory role of hepatocyte in liver regeneration at gene transcription level. Rat liver regeneration after partial hepatectomy (PH) is a good model to study the regulation of cell proliferation. We isolated hepatocytes from regenerating liver at 9 time points (2, 6, 12,24, 30, 36, 72, 120, and 168h) after PH and measured gene expression profiles of hepatocytes from 2h to 168h with rat Genome 230 2.0 gene chip. Each sample corresponding to one time point was hybridized onto one array. The experiment was repeated 3 times for each time point. In total, 10 time points were measured and 0h was used control group. After careful quality control analyses of each chip, Affymetrix GCOS 2.0 software was used to analyze the data. The relevance of gene expression profiles and biological processes was analyzed by bioinformatics and systems biology.
Project description:The study examined the role of TNF alpha in regulation of liver regeneration. For this purpose animals were divided in three groups of healthy controls, 2/3 partial hepatectomy alone, and animals pretreated with TNF alpha antagonist followed by 2/3 partial hepatectomy. Liver regeneration responses were then examined in conjunction with gene expression analysis at the peak of partial hepatectomy induced DNA synthesis. Substantive differences were identified in multiple gene ontology groups and cellular events and processes to indicate that TNF alpha was deleterious for partial hepatectomy induced liver regeneration.
Project description:Krüppel-like factor 6 (KLF6) is a transcription factor and tumor suppressor. Loss or reduction of KLF6 is linked with progression of experimental and human hepatocellular carcinoma. Despite its important contributions to liver homeostasis and growth, there are no data characterizing the involvement of KLF6 to hepatic regeneration. Microarray data from wildtype and DeltaKlf6 mice were used to identify regulating mechanisms and potential mediators within liver regeneration Wildtype and hepatocyte specific Klf6 knockout mice (DeltaKlf6) were employed for 70% partial liver resection/hepatectomy (PHx) in order to analyse liver regeneration. Twelve hours after partial hepatectomy animals were scrificed and remnant liver tissue was used for further experiemnts. For the overall study we used 6 animals per group, and included RNA from liver tissue of 3 wildtype and 3 DeltaKlf6 animals for the microarray analysis. Wildtype animals were used as controls.
Project description:The transcription factor Nuclear factor erythroid 2-related factor 2 (Nrf2) regulates an array of cytoprotective genes, yet studies in transgenic mice have led to conflicting reports on its role in liver regeneration. We aimed to test the hypothesis that pharmacological activation of Nrf2 would enhance liver regeneration. Wild type (WT) and Nrf2 null mice were administered bardoxolone methyl (CDDO-Me), a potent activator of Nrf2 that has entered clinical development, and then subjected to partial hepatectomy (PHx). CDDO-Me enhanced the rate of restoration of liver volume and improved liver function (multispectral optoacoustic imaging in wild type, but not Nrf2 null, mice following two-thirds partial hepatectomy. These effects were associated with an increase in hepatocyte hypertrophy and proliferation, the suppression of immune and inflammatory signals, and metabolic remodeling in the remnant liver tissue.
Project description:We studied the role of the post-translational modification called O-GlcNAcylation during liver regeneration. Here we generated O-GlcNAc transferase (OGT-KO) and O-GlcNAcase (OGA-KO) hepatocyte-specific knock-out mice. 70% partial hepatectomy (PHX) was performed to induce liver regeneration. We showed that OGA-KO mice had normal liver regeneration whereas OGT-KO mice had a defect in the termination of liver regeneration.
Project description:Disruption of the liver’s innate ability to regenerate represents an “undruggable” clinical challenge associated with poor patient outcomes. Yes-associated protein (YAP), a transcriptional co-activator which is repressed by the Hippo pathway, is instrumental in liver regeneration. We have previously described an alternative, Hippo-independent activation of YAP mediated by tyrosine-protein phosphatase non-receptor type 11 (SHP2) inhibition. Herein, we examined the effects of YAP activation with a selective SHP1/SHP2 inhibitor, NSC-87877, on liver regeneration in murine partial hepatectomy models. In our studies, NSC-87877 led to accelerated hepatocyte proliferation, improved liver regeneration, and decreased markers of injury following partial hepatectomy. Evaluation of these effects in mice with hepatocyte-specific Yap/Taz deletion demonstrated dependence on these molecules for the enhanced regenerative response. Furthermore, administration of NSC-87877 to murine models of non-alcoholic steatohepatitis was associated with improved survival and decreased markers of injury post-hepatectomy. Evaluation of transcriptomic changes in the context of NSC-87877 administration revealed reduction in fibrotic signaling and augmentation of cell cycle signaling. Cytoprotective changes included downregulation of Nr4a1, an apoptosis inducer. Collectively, the data suggest that SHP2 inhibition induce a YAP-dependent pro-proliferative and cytoprotective enhancement of liver regeneration.
Project description:Autonomic nervous system is widely distributed in liver, and some reserchers have found that disruppted autonomic nerves will delay liver regeneration. We used microarrays to further highlight the regulatory role of autonomic nervous system in liver regeneration at gene transcription level. Surgical operations of rat partial hepatectomy (PH) and its operation control (OC), sympathectomy combining partial hepatectomy (SPH), vagotomy combining partial hepatectomy (VPH), and total liver denervation combining partial hepatectomy (TDPH) were performed, and the expression profiles of regenerating liver at 2h were detected using Rat Genome 230 2.0 array. Then the significantly changed genes related to liver regeneration (LR)-, injury-, splanchnic nerve-LR-, vagal nerve-LR-, and autonomic nerve-LR-related genes were identified, respectively. The relevance of gene expression profiles and biological processes was analyzed by bioinformatics and systems biology.
Project description:Liver regeneration is an extraordinarily complex process involving a variety of factors; however, the role of chromatin protein in hepatocyte proliferation is largely unknown. In this study, we investigated the functional role of high-mobility group box 2 (HMGB2), a chromatin protein in liver regeneration using wild-type and HMGB2-knockout (KO) mice. Liver tissues were sampled after 70% partial hepatectomy (PHx), and analyzed by immunohistochemistry using various markers of cell proliferation, including Ki-67, PCNA, cyclin D1, cyclin B1, EdU and pH3S10. In WT mice, hepatocyte proliferation was strongly correlated with the spatiotemporal expression of HMGB2; however, cell proliferation was significantly delayed in hepatocytes of HMGB2-KO mice. Quantitative PCR demonstrated that cyclin D1 and cyclin B1 mRNAs were significantly decreased in HMGB2-KO mice livers. Interestingly, hepatocyte size was significantly larger in HMGB2-KO mice at 36-72 h after PHx, and these results suggest that hepatocyte hypertrophy appeared in parallel with delayed cell proliferation. In vitro experiments demonstrated that cell proliferation was significantly decreased in HMGB2-KO cells. A significant delay in cell proliferation was also found in HMGB2-siRNA transfected cells. In summary, spatiotemporal expression of HMGB2 is important for regulation of hepatocyte proliferation and cell size during liver regeneration.