Unknown,Transcriptomics,Genomics,Proteomics

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Mild vs advanced liver fibrosis

ABSTRACT: The aim of this study is to compare mild and advanced liver fibrosis gene expression profiling and to identify novel markers of fibrosis progression. By transcriptome analysis with a cDNA array virtually covering every transcript in liver, we compared transcript levels in mild (F1 Metavir score) and advanced (F4 Metavir score) fibrosis. A stringent selection identified a list of 16 transcripts which completely separated the 2 groups of patients (8 F1 and 8 F4). We report that dysregulations at the transcriptional level do exist between mild fibrosis (F1) and advanced fibrosis (F4). Keywords: fibrosis stage-dependent analysis Fibrosis samples were analyzed for 16 patients : 8 mild fibrosis (F1-1 to F1-8) and 8 advanced fibrosis (F4-1 to F4-8). All data in the current study were obtained from 3 separate hybridizations per RNA sample.

ORGANISM(S): Homo sapiens

SUBMITTER: Jean SALIER

PROVIDER: E-GEOD-11536 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:C/EBPβ plays a major role in numerous biological processes but unfortunately its precise role is not still clear and conflicting studies showed that this transcription factor could have contradictory functions. These latter arise from the complexity of mechanisms regulating C/EBPβ activity. Indeed, C/EBPβ encodes an intronless gene that generates a single mRNA that is alternatively translated into two major isoforms of 35kDa (liver-enriched activator protein: LAP) and 20kDa (liver-enriched inhibitory protein: LIP). LAP is the active isoform of this transcription factor whereas LIP, a truncated isoform negatively regulate C/EBPβ-LAP-mediated gene expression. The main goal of our research was to understand how LAP and LIP isoforms governe C/EBPβ cellular functions with the identification of new genes and pathways regulated by these isoforms in the human Hep3B hepatoma cell line. For this purpose an original in vitro system characterized by a target genes induction with the activatory C/EBPß isoform LAP and a target genes repression with the inhibitory C/EBPß isoform (LIP) was used to identify the genuine C/EBPβ molecular signature. Using a cDNA microarray which provides a complete coverage of the liver transcriptome, we identified 676 genes inversely regulated by LAP and LIP. These selected genes are involved in many biological processes as the hepatic metabolism (cholesterol), detoxification, induction of apoptosis and negative regulation of the cell proliferation. According to the involvement of C/EBPβ in hepatic carcinogenesis we focused on cell cycle regulation and apoptosis. Through functional studies, we proved for the first time that LIP plays in favor of the survival of the Hep3B cells whereas LAP makes the cells more sensitive to staurosporine-induced cell death. Moreover, a lot of studies demonstrated that the anti-proliferative action of C/EBPβ mainly depends on RB protein. By studying the rate of Hep3B cells proliferation which overexpress LAP, we brought to the fore that this isoform would be able to induce a repression of the Hep3B cells line proliferation - a RB- and p53- negative cell line. Thus, LAP seems able to induce the repression of proliferation by a different metabolic way from the RB one. Keywords: comparison of cells expressing LAP or LIP RNA were extracted from 5 Hep3BLAPexpressing LAP, 5 Hep3BLAP control without expression of LAP, 5 Hep3BLIP expressing LIP and 5 Hep3BLIP control without epression of LIP. Each sample was hybridized once in 5 different nylon membranes.

Project description:Background & Aims: Cirrhosis and liver cancer are potential outcomes of advanced nonalcoholic fatty liver disease (NAFLD). It is not clear what factors determine whether patients will develop advanced or mild NAFLD, limiting non-invasive diagnosis and treatment before clinical sequelae emerge. We investigated whether DNA methylation profiles can distinguish patients with mild disease from those with advanced NAFLD, and how these patterns are functionally related to hepatic gene expression. Methods: We collected frozen liver biopsies and clinical data from patients with biopsy-proven NAFLD (56 in the discovery cohort and 34 in the replication cohort). Samples were divided into groups based on histologic severity of fibrosis: F0?1 (mild) and F3?4 (advanced). DNA methylation profiles were determined and coupled with gene expression data from the same biopsies; differential methylation was validated in subsets of the discovery and replication cohorts. We then analyzed interactions between the methylome and transcriptome. Results: Clinical features did not differ between patients known to have mild or advanced fibrosis based on biopsy analysis. There were 69,247 differentially methylated CpG sites (76% hypomethylated, 24% hypermethylated) in patients with advanced vs mild NAFLD (P<.05). Methylation at FGFR2, MAT1A, and CASP1 was validated by bisulfite pyrosequencing and the findings were reproduced in the replication cohort. Methylation correlated with gene transcript levels for 7% of differentially methylated CpG sites, indicating that differential methylation contributes to differences in expression. In samples with advanced NAFLD, many tissue repair genes were hypomethylated and overexpressed, whereas genes in certain metabolic pathways, including 1-carbon metabolism, were hypermethylated and under-expressed. Conclusions: Functionally relevant differences in methylation can distinguish patients with advanced vs mild NAFLD. Altered methylation of genes that regulate processes such as steatohepatitis, fibrosis, and carcinogenesis indicate the role of DNA methylation in progression of NAFLD. Three technical replicates were included for quality control along with 35 mild NAFLD (33 unique samples) and 24 advanced NAFLD (23 unique sample). One sample per technical duplication was randomly included for a total of 56 NAFLD samples used for study.

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Mild vs advanced liver fibrosis

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