Project description:To investigate the cellular and molecular mechanisms that initiate liver regeneration and liver organoid formation, we performed RNA sequencing in the following cell types: hepatocytes from undamaged livers of mice as well as 6 h, 12 h, 24 h, 48 h, 72 h, 7 d, 14 d, 21 d of liver regeneration after PHx. Hep-Orgs were isolated from adult male mice hepatocytes and cultured for passages.
Project description:PPARα act as the master of lipid metabolism in liver, however, the changes of its target genes after PHx and the effects of PPARα on regenerative genes were unknown. At 12 to 24 hours after PHx, the mice develope marked steatosis, therefore the time point of 12 hour after PHx was choosen to perform microarray analysis. We used microarray to detail the gene expression of WT (Pparafl/fl) mice and hepatocyte-specific PPARα disruption (Ppara△Hep) mice liver tissue at 12 hour after PHx or Sham operation
Project description:The liver has a remarkable ability to regenerate, with the best experimental model for regeneration being partial hepatectomy (PHx), in which up to two-thirds of the liver may be removed, and the residual lobes enlarge to make up for the missing mass in a few days’ time. Liver regeneration has been extensively studied, mainly in rodent models, and characterized in terms of transcriptional regulation of gene expression. However, little is known regarding regulation of gene expression in a human model of regeneration following PHx. We used microarrays to follow gene expression changes shortly following PHx. Experiment Overall Design: Liver tissues were collected from patients undergoing a PHx surgery (1.5, 42 and 81 years) under an IRB approval, at the onset (T0) and shortly after PHx (0.5hr, 1hr and 1.5hrs) for RNA extraction and hybridization on Affymetrix microarrays.
Project description:The liver plays a central role in whole body metabolic regulation. Studies of liver metabolism are mostly done in vivo in animal models due to the lack of reliable in vitro systems that can recapitulate liver metabolic functions and their regulation. Hepatocyte organoids (HOs) generated in vitro recently are powerful tools for liver regeneration. Here we developed a novel culture condition that enabled successful generation of mature hepatocyte organoids (MHOs) with metabolic functions characteristic of adult livers. We showed that the MHOs can be used to study gene expression that exhibit zonal patterns in vivo, hepatic proliferation during tumorigenesis and metabolic alterations in disorders of both alcoholic and non-alcoholic fatty liver diseases.
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: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.
Project description:Recently, we have shown that after partial hepatectomy (PHx), an increased hepatic blood flow initiates liver growth in mice by vasodilation and mechanically-triggered release of angiocrine signals. Here, we use mass spectrometry to identify a mechanically-induced angiocrine signal in human hepatic endothelial cells, that is, myeloid-derived growth factor (MYDGF). We show that it induces proliferation and promotes survival of primary human hepatocytes derived from different donors in two-dimensional cell culture, via activation of mitogen-activated protein kinase (MAPK) and signal transducer and activator of transcription 3 (STAT3). MYDGF also enhances proliferation of human hepatocytes in three-dimensional organoids. In vivo, genetic deletion of MYDGF decreases hepatocyte proliferation in the regenerating mouse liver after PHx; conversely, adeno-associated viral delivery of MYDGF increases hepatocyte proliferation and MAPK signaling after PHx. We conclude that MYDGF represents a mechanically-induced angiocrine signal and that it triggers growth of, and provides protection to, primary mouse and human hepatocytes
Project description:The cellular and molecular mechanisms involved in liver regeneration following partial hepatectomy (PHx) are complicated. Liver sinusoidal endothelial cells (LSECs) play key roles in orchestrating liver regeneration, especially during the inductive phase and angiogenic phase post PHx (from day 0 to day 8). However, the expression profile of LSECs during the late phase of regeneration remains poorly explored. Thus, we purified LSECs from mice underwent PHx or sham operation at day 14 to unravel their transcriptome changes in the late phase of liver regeneration.