Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Reconstructing gene regulatory networks of tumorigenesis [genex]

ABSTRACT: The mechanistic links between transcription factors and the epigenetic landscape, which coordinate the deregulation of gene networks during cell transformation are largely unknown. We used an isogenic model of stepwise tumorigenic transformation of human primary cells to monitor the progressive deregulation of gene networks upon immortalization and oncogene-induced transformation. By combining transcriptome and epigenome data for each step during transformation and by integrating transcription factor (TF) - target gene associations, we identified 142 Tfs and 24 chromatin remodelers/modifiers (CRMs), which are preferentially associated with specific co-expression paths that originate from deregulated gene programming during tumorigenesis. These Tfs are involved in the regulation of divers processes, including cell differentiation, immune response and establishment/modification of the epigenome. Unexpectedly, the analysis of chromatin state dynamics revealed patterns that distinguish groups of genes, which are not only co-regulated but also functionally related. Further decortication of TF targets enabled us to define potential key regulators of cell transformation, which are engaged in RNA metabolism and chromatin remodelling. Our study suggests a direct implication of CRMs in oncogene-induced tumorigenesis and identifies new CRMs involved in this process. This is the first comprehensive view of gene regulatory networks that are altered during the process of stepwise human cellular tumorigenesis in a virtually isogenic system. Transcriptional activity in BJEL and BJELM cells has been evaluated and compared with that found in BJ cells; 2 biological replicates per cell line

ORGANISM(S): Homo sapiens

SUBMITTER: Valeriya Malysheva

PROVIDER: E-GEOD-72530 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Osteoarthritis is a degenerative joint disease that ranks among the leading causes of pain, adult disability, shortening of working life, and socioeconomic costs worldwide. The mechanisms underlying osteoarthritis pathogenesis are yet to be fully elucidated, thus limiting current disease management and treatment. Galectin-1 is an endogenous carbohydrate-binding protein central to adhesion via glycan-bridging, glycoconjugate-mediated signaling, cell proliferation, differentiation, apoptosis, cancers, and host-pathogen interactions. The chondrocyte glycophenotype, which can act as a system of counter-receptors for galectin binding, is compromised in osteoarthritis. We here investigated Galectin-1 and associated gene network's role in human osteoarthritis pathogenesis. Immunohistochemical analysis showed that Galectin-1 associates with osteoarthritic cartilage and subchondral bone histopathology and severity (p<0.0001, n=29 patients). Glycan-dependent Galectin-1 binding to osteoarthritic chondrocytes' cell surface led to marked upregulation of matrix metalloproteinases and activation of NF-ÎºB. Biochemical, molecular and genome-wide analyses showed that Galectin-1 strongly activates a large inflammatory gene network (p<10-16). Bioinformatic analyses of gene promoters up-regulated by Galectin-1 unveiled an overwhelming NF-ÎºB signaling signature. Inhibition of any of several components of the NF-ÎºB pathway using dedicated inhibitors led to dose-dependent impairment of Galectin-1-mediated transcriptional activation. This study identifies for the first time Galectin-1 as an activator of clinically relevant inflammatory-response genes co-regulated by NF-ÎºB. Since inflammation is critical to cartilage degeneration in osteoarthritis, this report is also first to put glycobiology at the center-stage of osteoarthritic cartilage degeneration. Finally, this is the first report to uncover a Galectin-1 gene signature and associated gene network in any biological setting or species. For microarray experiments, osteoarthritic chondrocytes were isolated from five male patients (47-78 years). Following starvation, cells were incubated in the presence of 50 Âµg/ml recombinant Galectin-1 for 24 h. For each donor population, untreated cells were included as control. In total, 10 samples were analyzed.

Project description:Î³-secretase is an intra-membrane-cleaving aspartyl protease implicated in the processing of a wide range of type I membrane proteins including the Notch receptor and the amyloid-Î² precursor protein (APP). It thus regulates a diverse array of cellular and biological processes including the differentiation of neuronal embryonic stem cells, or intestinal stem cells, with the latter controlling the self-renewing of the intestinal epithelium. Indeed, proteolysis of these proteins by Î³-secretase triggers signaling cascades by releasing intracellular domains (ICDs) which, following association with adaptor proteins and nuclear translocation, modulate the transcription of different genes by binding directly to their promoters. The pronounced proliferative and regenerative effects of Notch signaling and its implication in the generation of the AÎ²-peptides, makes Î³-secretase a therapeutic target for several types of cancer and for Alzheimerâs disease. To investigate the broad effects of Î³-secretase activity onto the cellular transcriptome, Chinese hamster ovary (CHO) cells with enhanced Î³-secretase were compared to cells with abolished Î³-secretase activity via a microarray designed for a genetically close species, mouse. Our findings will potentially help to decipher the biology of Î³-secretase, including a better understanding of the roles of this enzyme in gene transcription. We compared the transcriptomes of two CHO cell lines displaying extreme differences in Î³-secretase activity. The S-1 cell line overexpressed the four components of Î³-secretase (NCT, APH1aL, PS1, and PEN2) and was characterized by a marked increase in the level of PS1 heterodimers associated with 8-fold increased Î³-secretase activity compared to untransfected controls. The other cell line consisted of wild type CHO cells incubated with DAPT, a well-known Î³-secretase inhibitor. The two cell lines were used in combination with a mouse microarray to analyze gene transcription under enhanced Î³-secretase. Two samples, S1 and DAPT treated CHO- were used in biological triplicates each.

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Reconstructing gene regulatory networks of tumorigenesis [genex]

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