Project description:We isolated liver sinusoidal endothelial cells (LSEC) from mice fed control chow (Chow) or the nonalcoholic steatohepatitis (NASH)-inducing high fat, fructose and cholesterol (FFC) diet, and subjected the cells to Omni-ATAC-seq. Out of the top 500 differentially abundant open chromatin regions between the two groups, 498 were more robust in FFC-fed mice compared with Chow-fed mice, suggesting a genome-wide active epigenetic regulation in LSEC during NASH development. Furthermore, in combination with RNA-seq, we demonstrated a robust transcriptional upregulation of the adhesion molecule VCAM-1 in LSEC in NASH pathogenesis.
Project description:Non-alcoholic fatty liver disease (NAFLD) is characterized by a series of pathological changes that can progress from simple fatty liver disease to non-alcoholic steatohepatitis (NASH). The objective of this study is to describe changes in global gene expression associated with the progression of NAFLD. This study is focused on the expression levels of genes responsible for the absorption, distribution, metabolism and excretion (ADME) of drugs. Differential gene expression between three clinically defined pathological groups; normal, steatosis and NASH was analyzed. The samples were diagnosed as normal, steatotic, NASH with fatty liver (NASH fatty) and NASH without fatty liver (NASH NF). Genome-wide mRNA levels in samples of human liver tissue were assayed with Affymetrix GeneChipM-. Human 1.0ST arrays
Project description:BACKGROUND & AIMS: Recent studies revealed that hemoglobin is expressed in some non-erythrocytes and it suppresses oxidative stress when overexpressed. Oxidative stress plays a critical role in the pathogenesis of non-alcoholic steatohepatitis (NASH). This study was to investigate whether hemoglobin is expressed in hepatocytes and how it is related to oxidative stress in NASH patients. METHODS: Microarray was performed to identify differentially expressed genes in NASH. Quantitative real time PCR (qRT-PCR) was used to examine gene expression levels. Western blotting and immunofluorescence staining were employed to examine hemoglobin proteins. Flow cytometry was used to measure intracellular oxidative stress. RESULTS: Analysis of microarray gene expression data has revealed a significant increase in the expression of hemoglobin alpha (HBA1) and beta (HBB) in liver biopspies from NASH patients. Increased hemoglobin expression in NASH was validated by qRT-PCR. However, the expression of erythrocyte specific marker genes such as SPTA, SPTB, GYPA, GATA1, and ALAS2 did not change, indicating that increased hemoglobin expression in NASH was not from erythropoiesis, but could result from increased expression in hepatocytes. Immunofluorescence staining demonstrated positive HBA1 and HBB expression in the hepatocytes of NASH livers. Hemoglobin expression was also observed in human hepatocellular carcinoma HepG2 cell line. Furthermore, treatment with hydrogen peroxide, a known oxidative stress inducer, induced a dose dependent increase in HBA1 expression in HepG2 cells. Intriguingly, forced hemoglobin expression suppressed oxidative stress. CONCLUSIONS: Oxidative stress upregulates hemoglobin expression in hepatocytes. Suppression of oxidative stress by hemoglobin could be a mechanism to protect hepatocytes from oxidative damage. These findings suggest that hemoglobin is an inducible antioxidant in hepatocytes in response to increased oxidative stress as found in NASH livers. Twelve biopsy diagnosed NASH patients were included in this study. For control groups, total RNA from 5 different subjects were purchased from ADMET. These subjects are free from liver disease.
Project description:The mechanisms underlying the progression of non-alcoholic steatohepatitis (NASH) are not completely elucidated. In this study we have integrated gene expression profiling of liver biopsies of NASH patients with translational studies in a mouse model of steatohepatitis and with pharmacological interventions in isolated hepatocytes to identify a novel mechanism implicated in the pathogenesis of NASH. By using high-density oligonucleotide microarray analysis we identified a significant enrichment of known genes involved in the multi-step catalysis of long chain polyunsaturated fatty acids, including delta-5 and 6 desaturases. A combined inhibitor of delta-5 and delta-6 desaturases significantly reduced intracellular lipid accumulation and inflammatory gene expression in isolated hepatocytes. Gas chromatography analysis revealed impaired delta-5 desaturase activity toward the omega-3 pathway in livers from mice with high-fat diet (HFD)-induced NASH. Consistently, restoration of omega-3 index in transgenic fat-1 mice expressing an omega-3 desaturase, which allows the endogenous conversion of omega-6 into omega-3 fatty acids, produced a significant reduction in hepatic insulin resistance, hepatic steatosis, macrophage infiltration and necroinflammatory liver injury, accompanied by attenuated expression of genes involved in inflammation, fatty acid uptake and lipogenesis. These results were comparable to those obtained in a group of mice receiving a HFD supplemented with EPA/DHA. Of interest, hepatocytes from fat-1 mice or supplemented with EPA exhibited synergistic anti-steatotic and anti-inflammatory actions with the delta-5/ delta-6 inhibitor. Conclusion: These findings indicate that both endogenous and exogenous restoration of the hepatic balance between omega-6 and omega-3 fatty acids and/or modulation of desaturase activities exert preventive actions in NASH. The complete database comprised the expression measurements of 18185 genes for liver sample groups: 8 non-alcoholic steatohepatitis (NASH ) and 7 control samples. This dataset is part of the TransQST collection.
Project description:Nonalcoholic steatohepatitis (NASH) is a progressive liver disease that is characterized by liver injury, inflammation and fibrosis. NASH pathogenesis is linked to reprogramming of chromatin landscape in the liver that predisposes hepatocytes to stress-induced tissue injury. However, the molecular nature of the putative checkpoint that maintains chromatin architecture and preserves hepatocyte health remains elusive. Here we show that heterogeneous nuclear ribonucleoprotein U (hnRNPU), a nuclear matrix protein that governs chromatin architecture and gene transcription, is a critical factor that couples chromatin disruption to NASH pathogenesis. RNA-seq and ChIP-seq studies revealed an extensive overlap between hnRNPU occupancy and altered gene expression during NASH. Hepatocyte-specific inactivation of hnRNPU disrupted liver chromatin accessibility, activated the molecular signature of NASH and sensitized mice to diet-induced NASH pathogenesis. Mechanistically, hnRNPU deficiency stimulated the expression of a truncated isoform of TrkB that promotes inflammatory signaling in hepatocytes and stress-induced cell death. These findings illustrate a novel mechanism through which disruptions of chromatin architecture drive the emergence of disease-specific signaling patterns that promote liver injury and exacerbate NASH pathogenesis.
Project description:OBJECTIVE: Nonalcoholic steatohepatitis (NASH) is closely associated with metabolic syndrome and increases the risk for end-stage liver disease, such as cirrhosis and hepatocellular carcinoma. Despite this, the molecular events that influence NASH pathogenesis remain poorly understood. The objectives of the current study are to delineate the transcriptomic and proteomic signatures of NASH liver, to identify potential pathogenic pathways and factors, and to critically assess their role in NASH pathogenesis. METHODS: We performed RNA sequencing and quantitative proteomic analyses on the livers from healthy and diet-induced NASH mice. We examined the association between plasma levels of TSK, a newly discovered hepatokine, and NASH pathologies and reversal in response to dietary switch in mice. Using TSK knockout mouse model, we determined how TSK deficiency modulates key aspects of NASH pathogenesis. RESULTS: RNA sequencing and quantitative proteomic analyses revealed that diet-induced NASH triggers concordant reprogramming of the liver transcriptome and proteome in mice. NASH pathogenesis is linked to elevated plasma levels of the hepatokine TSK, whereas dietary switch reverses NASH pathologies and reduces circulating TSK concentrations. Finally, TSK inactivation protects mice from diet-induced NASH and liver transcriptome remodeling. CONCLUSIONS: Global transcriptomic and proteomic profiling of healthy and NASH livers revealed the molecular signatures of diet-induced NASH and dysregulation of the liver secretome. Our study illustrates a novel pathogenic mechanism through which elevated TSK in circulation promotes NASH pathologies, thereby revealing a potential target for therapeutic intervention.
Project description:Whole liver from mice with diet-induced nonalcoholic fatty liver disease (NASH) was subjected to bulk RNA-seq. Ingenuity pathway analysis implicated pathways related to the leukocyte adhesion and differentiation in the pathogenesis of NASH. Among the adhesion molecules expressed in endothelial cells, only Icam1 (Log2FC: 1.99; FDR: 1.55E-37) and Vcam1 (Log2FC: 1.93; FDR: 9.32E-35) were differentially upregulated in NASH liver.
Project description:Non-alcoholic fatty liver disease/steatohepatitis (NAFLD/NASH) is a significant risk factor for hepatocellular carcinoma (HCC). However, a preclinical model of progressive NAFLD/NASH is largely lacking. Here, we report that mice with hepatocyte-specific deletion of Tid1, encoding a mitochondrial cochaperone, tended to develop NASH-dependent HCC. Mice with hepatic Tid1 deficiency showed impairing mitochondrial function and causing fatty acid metabolic dysregulation; meanwhile, sequentially developed fatty liver, NASH, and cirrhosis/HCC in a diethylnitrosamine (DEN) induced oxidative environment. The pathological signatures of human NASH, including cholesterol accumulation and activation of inflammatory and apoptotic signaling pathways, are also present in these mice. Clinically, low Tid1 expression was associated with unfavorable prognosis in patients with HCC. Empirically, hepatic Tid1 deficiency directly disrupts entire mitochondria that play a key role in the NASH-dependent HCC development. Overall, we established a new mouse model that develops NASH-dependent HCC and provides a promising approach to improve the treatment.
Project description:To improve the understanding of the complex biological processes underlying the development of non-alcoholic steatohepatitis (NASH), a multi-omics approach combining bulk RNA-sequencing based transcriptomics, quantitative proteomics and single-cell RNA-sequencing was used to characterize tissue biopsies from histologically validated diet-induced obese (DIO) NASH mice compared to chow-fed controls. Bulk RNA-sequencing and proteomics showed a clear distinction between phenotypes and a good correspondence between mRNA and protein level regulations, apart from specific regulatory events discovered by each technology. Transcriptomics-based gene set enrichment analysis revealed changes associated with key clinical manifestations of NASH, including impaired lipid metabolism, increased extracellular matrix formation/remodeling and pro-inflammatory responses, whereas proteomics-based gene set enrichment analysis pinpointed metabolic pathway perturbations. Integration with single-cell RNA-sequencing data identified key regulated cell types involved in development of NASH demonstrating the cellular heterogeneity and complexity of NASH pathogenesis.
Project description:Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of disease that ranges from simple steatosis, to inflammatory form non-alcoholic steatohepatitis (NASH), cirrhosis, and up to hepatocellular carcinoma. While NASH usually takes decades to develop at a rate of one stage per seven years, in the case of post-trasplant NASH (pt-NASH) develops fibrosis much more rapidly, with almost 50% of liver transplant recipients presenting stage 3 fibrosis by 5 years post-transplant. Archived fresh-frozen transplanted liver biopsy samples from four liver biopsy samples with evidence of NASH (2 recurrent and 2 de novo), two with simple steatosis (both de novo), and five with normal histology as controls had their transcriptome sequenced in two batches for deeper coverage.