Transcription profiling of liver from p38aDhep, IkkbDhep, and control mice 4h after injection of diethylnitrosamine
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ABSTRACT: Analysis of microarray data from livers 4 hr after DEN administration revealed changes in the expression of several genes relevant to regulation of reactive oxygen species (ROS) accumulation, cell death, and cell cycle control.
Project description:Microarray expression profiling has become a valuable tool in the evaluation of the genetic consequences of metabolic disease. Although 3â??-biased gene expression microarray platforms were the first generation to have widespread availability, newer platforms are gradually emerging that have more up-to-date content and/or higher cost efficiency. Deciphering the relative strengths and weaknesses of these various platforms for metabolic pathway level analyses can be daunting. We sought to determine the practical strengths and weaknesses of four leading commercially-available expression array platforms relative to biologic investigations, as well as assess the feasibility of cross-platform data integration for purposes of biochemical pathway analyses. METHODS: Liver RNA from B6.Alb/cre,Pdss2loxP/loxP mice having primary Coenzyme Q deficiency was extracted either at baseline or following treatment with an antioxidant/antihyperlipidemic agent, probucol. Target RNA samples were prepared and hybridized to Affymetrix 430 2.0, Affymetrix Gene 1.0 ST, Affymetrix Exon 1.0 ST, and Illumina Mouse WG-6 expression arrays. Probes on all platforms were re-mapped to coding sequences in the current version of the mouse genome. Data processing and statistical analysis were performed by R/Bioconductor functions, and pathway analyses were carried out by KEGG Atlas and GSEA. RESULTS: Expression measurements were generally consistent across platforms. However, intensive probe-level comparison suggested that differences in probe locations were a major source of inter-platform variance. In addition, genes expressed at low or intermediate levels had lower inter-platform reproducibility than highly expressed genes. All platforms showed similar patterns of differential expression between sample groups, with â??steroid biosynthesisâ?? consistently identified as the most down-regulated metabolic pathway by probucol treatment. CONCLUSIONS: This work offers a timely guide for metabolic disease investigators to enable informed end-user decisions regarding choice of expression microarray platform best-suited to specific research project goals. Successful cross-platform integration of biochemical pathway expression data is also demonstrated, especially for well-annotated and highly-expressed genes. However, integration of gene-level expression data is limited by individual platform probe design and the expression level of target genes. Cross-platform analyses of biochemical pathway data will require additional data processing and novel computational bioinformatics tools to address unique statistical challenges. 4 samples are analyzed on each of 4 different Mouse Microarray Expression platforms (Affymetrix Mo430 2.0, Affymetrix Gene, Affymetrix Exon 1.0 ST, and Illumina Whole Genome 6).
Project description:The liver plays a central role in whole-body lipid and glucose homeostasis. Increasing dietary fat intake results in increased hepatic fat deposition, which is associated with a risk for development of insulin resistance and type 2 diabetes. In this study, we demonstrate a role for the phosphate inorganic transporter 1 (PiT1/SLC20A1) in regulating metabolism. Specific knockout of Pit1 in hepatocytes significantly improved glucose tolerance and insulin sensitivity, enhanced insulin signalling, and decreased hepatic lipogenesis. We identified USP7 as a PiT1 binding partner and demonstrated that Pit1 deletion inhibited USP7/IRS1 dissociation upon insulin stimulation. This prevented IRS1 ubiquitination and its subsequent proteasomal degradation. As a consequence delayed insulin negative feedback loop and sustained insulin signalling were observed. Moreover, PiT1-deficient mice were protected against high fat diet-induced obesity and diabetes. Our findings indicate that PiT1 has potential as a therapeutic target in the context of metabolic syndrome, obesity, and diabetes.
Project description:A proteomics analysis with quantitative tandem mass tag mass spectrometry (TMT-MS) was performed to screen for altered hepatocyte proteins in the livers of PDI-deficient versus control mice.
Project description:Suppressor of cytokine signaling 3 (SOCS3) down-regulates several signaling pathways in multiple cell types, and previous data suggest that SOCS3 may shut off cytokine activation at the early stages of liver regeneration. We developed hepatocyte-specific Socs3 knockout (Socs3 h-KO) mice to directly study the role of SOCS3 during liver regeneration after 2/3 partial hepatectomy (PH). Socs3 h-KO mice demonstrate marked enhancement of DNA replication and liver weight restoration after 2/3 PH in comparison with littermate controls. Without SOCS3, signal transducer and activator of transcription 3 (STAT3) phosphorylation is prolonged, and activation of the mitogenic kinases extracellular signal-regulated kinase 1/2 (ERK1/2) is enhanced after PH. In vitro, we show that SOCS3 deficiency enhances hepatocyte proliferation in association with enhanced STAT3 and ERK activation after epidermal growth factor (EGF) or interleukin 6 (IL-6) stimulation. Microarray analyses show that SOCS3 modulates a distinct set of genes after PH, which fall into diverse physiologic categories. Using a model of chemical-induced carcinogenesis, we found that Socs3 h-KO mice develop hepatocellular carcinoma (HCC) at an accelerated rate. By acting on cytokines and multiple proliferative pathways, SOCS3 modulates both physiologic and neoplastic proliferative processes in the liver, and may act as a tumor suppressor. Experiment Overall Design: Hepatocyte-specific excision of the Socs3 gene was achieved by breeding Socs3 fl/fl mice with mice expressing the Cre recombinase transgene under control of the albumin promoter (Alb-Cre+), yielding Socs3 h-KO mice. Socs3 fl/fl, Alb-Cre- littermates were used as controls for all experiments, and are henceforth referred to as littermates. All mice (C57BL/6) were free of Helicobacter species, housed in a specific pathogen free facility with 12-h light/dark cycles with free access to standard food and water. 2/3 PH and sham operations were performed as previously described (15, 50) (n=3-6 mice per genotype per time point). Liver remnants were weighed after removal of necrotic stumps and sutures, and compared to post-operative body weight. For HCC experiments, a single i.p. injection of DEN (5mg/kg, Sigma) was performed 12-14 d after birth. For short time points, a single injection of DEN (100mg/kg) (31) was given to 4 wk old mice. At indicated time points, mice were sacrificed by CO2 inhalation. All animal studies were carried out under approved IACUC protocols at the University of Washington.
Project description:The HGF/c-Met system is an essential inducer of hepatocyte growth and proliferation. Although a fundamental role for the HGF receptor c-Met has been demonstrated in acute liver regeneration its cell specific role in hepatocytes during chronic liver injury and fibrosis progression has not been determined yet. In order to better characterize the role of c-Met in hepatocytes we generated a hepatocyte-specific c-Met knockout mouse (c-MetM-bM-^HM-^Fhepa) using the Cre-loxP system and studied its relevance after bile-duct ligation. Two strategies for c-Met deletion in hepatocytes were tested. Early deletion during embryonic development was lethal, while post-natal Cre-expression was successful leading to the generation of viable c-MetM-bM-^HM-^Fhepa mice. Bile-duct ligation in these mice resulted in extensive necrosis and lower proliferation rates of hepatocytes. Gene array analysis of c-MetM-bM-^HM-^Fhepa mice revealed a significant reduction of anti-apoptotic genes in c-Met deleted hepatocytes. These findings could be functionally tested as c-MetM-bM-^HM-^Fhepa mice showed a stronger apoptotic response after bile-duct ligation and Jo-2 stimulation. This phenotype was associated with increased expression of pro-inflammatory cytokines (TNF-a and IL-6) and an enhanced recruitment of neutrophils. Activation of these mechanisms triggered a stronger pro-fibrogenic response as evidenced by increased TGF-b1, a-SMA, collagen-1a mRNA expression and enhanced collagen-fiber staining in c-MetM-bM-^HM-^Fhepa mice. For gene array analysis c-MetDhepa and c-MetloxP/loxP controls were stimulated for 2 hours with 2M-BM-5g recombinant mouse HGF.Three animals per group were treated in parallel, before and after i.p. injection of recombinant HGF or NaCl.
Project description:A "Cartes d'Identite des Tumeurs" (CIT) project from the french Ligue Nationale Contre le Cancer (http://cit.ligue-cancer.net). This work aims to demonstrate a key role for the Wnt/beta-catenin pathway in liver embryonic growth and in controlling the fate of hepatoblasts, preventing them to differentiate towards the hepatocyte lineage, and guiding them to a duct morphogenesis. Through the inactivation of Apc (adenomatous Polyposis Coli) tumor suppressor gene in hepatoblasts by a Cre-loxP strategy, the ectopic activation of beta-catenin targeted in hepatoblasts after liver bud formation leads to a lethal embryonic phenotype, characterized by liver hypoplasia, a blockade of hepatocyte differentiation and commitment to a biliary fate. (this work was supported by INSERM and the B^SLigue Nationale
Project description:Quiescent hepatic stem cells (HSCs) can be activated when hepatocyte proliferation is compromised. Chemical injury rodent models have been widely used to study the locazation, biomarkers, and signaling pathways in HSCs, but these models usually exhibit severe promiscuous toxicity and fail to distinguish damaged and non-damaged cells. Our goal is to establish new animal models to overcome these limitations, thereby providing new insights into HSC biology and application. We generated mutant mice with constitutive or inducible deletion of Damaged DNA Binding protein 1 (DDB1), an E3 ubiquitin ligase, in hepatocytes. We show that deletion of DDB1 abolishes self-renewal capacity of mouse hepatocytes in vivo, leading to compensatory activation and proliferation of DDB1-expressing OCs. Importantly, the DDB1 mutant mice exhibit very minor liver damage, compared to a chemical injury model. Microarray analysis reveals several previously unrecognized markers, enriched in oval cells. This genetic model in which irreversible inhibition of hepatocyte duplication results in HSC-driven liver regeneration. The DDB1 mutant mice can be broadly applied to studies of HSC differentiation, HSC niche and HSCs as origin of liver cancer. Total RNA obtained from isolated EpCAM+ cells from DDB1 mutant mice compared to wild type hepatocytes
Project description:Double transgenic mice with hepatocyte-specific expression of AEG-1 and c-Myc show aggressive HCC compared to single transgenics. Gene expression was analyzed to understand the molecular mechanism by which AEG-1 and c-Myc cooperate to promote hepatocarcinogenesis. Livers were collected from naïve adult mice (3 mice/group). Total RNA was extrancted and subjected to RNA-Seq.
Project description:Short- and long-interval response of JY cells treated with Trichostatin A (TSA), used in gene pathway analysis. <br><br>Please note that the "Target IDs" used in the user submitted data files have been mapped to Illumina Probe_Ids (as recommended by Illumina) and this mapping is not 1 to 1. Original user submitted files have been included in the .mageml.tar.gz archive on the FTP site for this experiment.