Project description:Nonalcoholic steatohepatitis (NASH) is a severe form of nonalcoholic fatty liver disease (NAFLD) that is characterized by hepatic steatosis, inflammation, hepatocellular injury, and fibrosis, which lead to progressed cirrhosis and hepatocellular carcinoma. Despite its increasing prevalence on a global scale, the pathogenesis of NASH progression is not well understood. To elucidate the underlying mechanisms of NASH progression, we conducted transcriptome analyses of Japanese NAFLD cohort in our facility.
Project description:Chronic liver diseases are worldwide on the rise. Due to the rapidly increasing incidence, in particular in Western countries, non-alcoholic fatty liver disease (NAFLD) is gaining importance. As the disease progresses it can develop into hepatocellular carcinoma. Lipid accumulation in hepatocytes has been identified as the characteristic structural change in NAFLD development, but the molecular mechanisms responsible for disease development remained unresolved. Here, we uncover a strong downregulation of the PI3K-AKT pathway and an upregulation of the MAPK pathway in primary hepatocytes from a preclinical model fed with a Western diet (WD). Dynamic pathway modeling of hepatocyte growth factor (HGF) signal transduction combined with global proteomics identifies that an elevated basal MET phosphorylation rate is the main driver of altered signaling leading to increased proliferation of WD-hepatocytes. Model-adaptation to patient-derived hepatocytes reveals a patient-specific variability in basal MET phosphorylation, which correlates with the outcome of patients after liver surgery. Thus, dysregulated basal MET phosphorylation could be an indicator for the health status of the liver and thereby inform on the risk of a patient to suffer from liver failure after surgery.
Project description:Dysregulation of YY1 has been observed in many human cancers. Recent studies have shown that overexpression of YY1 plays a pivotal role in the initiation and progression of nonalcoholic fatty liver disease (NAFLD) which may further progress into hepatocellular carcinoma (HCC). To obtain a detailed view of genes and pathways regulated by YY1 in the liver, we carried out global RNA-seq in liver HepG2 cells with YY1 knocked down.
Project description:Immune dysregulation and inflammation by hepatic-resident leukocytes is considered a key step in disease progression of Non-alcoholic fatty liver disease (NAFLD) and Nonalcoholic steatohepatitis (NASH) toward cirrhosis and hepatocellular carcinoma (HCC). Here we provide a robust protocol for isolation and characterization of liver-resident immune cells from fine needle biopsies of rodent model and human. Various downstream applications can then be applied to gain an appreciation of the functional activity of liver-resident leukocyte populations.
Project description:Nonalcoholic Fatty Liver Disease (NAFLD) is a broad spectrum of liver disorders ranging from simple steatosis to nonalcoholic steatohepatitis, cirrhosis and hepatocellular carcinoma. The choline-deficient L-amino acid-defined (CDAA) diet-induced NAFLD animal model has traditionally been used to understand the molecular mechanisms of disease development and progression. Although this animal model shows a similar course of disease progression to human NAFLD, it does not develop comorbidities such as obesity and type 2 diabetes. Therefore, its relevance to human NAFLD (what aspects of the disease etiology are recapitulated in this model?) is not fully understood. We applied microarray analysis to characterize its pathophysiology, and evaluate the similarity across species.
Project description:Nonalcoholic steatohepatitis (NASH), a severe form of nonalcoholic fatty liver disease, is characterized by hepatic steatosis and hepatocellular injury and progresss cirrhosis and hepatocellular carcinoma. Sterol regulatory elment-binding proteins (SREBPs) are master regulators of lipogenesis. Liver-specific PTEN knockout (KO) mice show constitutive upregulation of SREBP through PI3K-Akt pathway activation, leading to spontaneous fatty liver and subsequent HCC development. SREBP cleavage-activating protein (SCAP) plays a critical role in SREBP activation. We sought to determine the impact of SREBP inhibition on NASH and HCC development. To this end, we additionaly inhibited SREBP pathway in liver-specific PTEN mice by ablating SCAP and generated liver-specific PTEN/SCAP double KO (DKO) mice. However unexpectedly, inhibition of SCAP/SREBP pathway markedly exacerbated liver injury (5weeks), fibrosis (5months), and carcinogenesis (7 months) in PTEN KO mice. To elucidate the mechanisms of liver tumorigenesis in liver-specific PTEN/SCAP DKO mice, we conducted transcriptome analyses of the livers.
Project description:Nonalcoholic steatohepatitis (NASH), a severe form of nonalcoholic fatty liver disease, is characterized by hepatic steatosis and hepatocellular injury and progresses to cirrhosis and hepatocellular carcinoma. Sterol regulatory element-binding proteins (SREBPs) are master regulators of lipogenesis. Liver-specific PTEN knockout (KO) mice show constitutive upregulation of SREBP through PI3K-Akt pathway activation, leading to spontaneous fatty liver and subsequent HCC development. SREBP cleavage-activating protein (SCAP) plays a critical role in SREBP activation. We sought to determine the impact of SREBP inhibition on NASH and HCC development. To this end, we additionally inhibited SREBP pathway in liver-specific PTEN mice by ablating SCAP and generated liver-specific PTEN/SCAP double KO (DKO) mice. However unexpectedly, inhibition of SCAP/SREBP pathway markedly exacerbated liver injury (5weeks), fibrosis (5months), and carcinogenesis (7 months) in PTEN KO mice. To elucidate the mechanisms of liver injury in liver-specific PTEN/SCAP DKO mice, we conducted transcriptome analyses of the livers.
Project description:The genomic landscape of hepatic tissue affected by nonalcoholic steatohepatitis (NASH) in severely obese adolescents undergoing bariatric surgery is unknown. Our purpose here was to uncover genomic profiles of obese controls, and obese cases with nonalcoholic fatty liver disease (NAFLD), borderline nonalcoholic steatohepatitis, and definite nonalcoholic steatohepatitis, in order to clarify molecular functions, biological processes, and pathways that are dysregulated in nonalcoholic steatohepatitis in the severely obese adolescent. In a prospective observational cohort study, we have intra-operatively obtained 165 liver samples; of these 67 were submited for microarray analysis. Through ANOVA, we found 8648 genes with differential regulation between the four histologies; from these, we uncovered gene signatures shared between borderline and definite nonalcoholic steatohepatitis, and gene sets with differential effects between borderline and definite.
Project description:Non-alcoholic fatty liver disease (NAFLD) is the number one cause of chronic liver disease worldwide, with 25% of these patients developing nonalcoholic steatohepatitis (NASH). NASH significantly increases the risk of cirrhosis and decompensated liver failure. Past studies in rodent models have shown the knockout of glycine-N-methyltransferase (GNMT) results in rapid pro-gression of steatosis, fibrosis, and hepatocellular carcinoma. However, the attenuation of GNMT in subjects with NASH and the molecular basis for its impact on the disease process are still unclear. To address this knowledge gap, we show the reduction of GNMT protein levels in the liver of NASH subjects compared to healthy controls. To gain insight into the impact of decreased GNMT in the disease process, we performed global label-free proteome studies on the livers from a murine Western diet-based model of NASH. Histological and molecular characterization of the animal model demonstrate high resemblance to the human disease.
Project description:With an estimated prevalence of about 30% in western countries non-alcoholic fatty liver disease (NAFLD) is a major public health issue [PMID: 18956290]. NAFLD is associated with the metabolic syndrome of insulin resistance, obesity, glucose intolerance. Although many studies are pointing to an induction of insulin resistance by NAFLD causality between both phenotypes is not fully clarified. Furthermore, mechanisms leading to strongly differing progression of NAFLD have to be elucidated which range from mild steatosis up to severe steatohepatitis. Steatohepatitis might even result in liver cirrhosis and hepatocellular carcinoma. Additional complexity is introduced into the understanding of the disease by recent studies providing evidence for a direct development of carcinoma from steatosis without the formerly assumed intermediary phase of cirrhosis. Here, we investigate liver samples from patients with varying severities of steatosis in an integrative approach employing transcriptomics, serum biomarker profling, metabolomics data and systems biology models. Total RNA obtained from hepatocytes derived from nine obese patients with distinct grades of steatosis. This dataset is part of the TransQST collection.