Reconstruction of gene interaction networks by in vitro RNA interference and global expression analysis
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ABSTRACT:
ORGANISM(S): Homo sapiens
SUBMITTER: Fellmann Mark
PROVIDER: S-ECPF-GEOD-12291 | biostudies-other |
REPOSITORIES: biostudies-other
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Project description:We here used the technology of RNA interference or selective treatment of the ESR1 and cDNA microarrays to reconstruct a network between genes known to be disregulated in ER-positive breast cancer diseases. Therefor single genes of high importance were silenced and the effect of this pertubation was measured with cDNA microarrays. Keywords: Network Reconstruction, RNAi, siRNA, Interaction Network human ER-positive breast cancer cell line was cultivated as described and transfection with chemically synthesized siRNAs was performed according to standard HiPerFect transfection protocol by Qiagen (Hilden, Germany) At least 4 cDNA-microarrays were hybridized in dye-swap method for the silencing of every gene of interest. To minimize off-target effects we used at least two different siRNAs per gene.
2009-07-29 | E-GEOD-12291 | biostudies-arrayexpress
Project description:We here used the technology of RNA interference or selective treatment of the ESR1 and cDNA microarrays to reconstruct a network between genes known to be disregulated in ER-positive breast cancer diseases. Therefor single genes of high importance were silenced and the effect of this pertubation was measured with cDNA microarrays. Keywords: Network Reconstruction, RNAi, siRNA, Interaction Network
2009-07-29 | GSE12291 | GEO
Project description:Histone modifications influence gene expression in complex ways. The RNA interference (RNAi) machinery can repress transcription by recruiting histone-modifying enzymes to chromatin, although it is not clear whether this is a general mechanism for gene silencing or whether it requires repeated sequences such as long terminal repeats (LTRs). We analyzed the global effects of the Clr3 and Clr6 histone deacetylases, the Clr4 methyltransferase, the zinc finger protein Clr1, and the RNAi proteins Dicer, RdRP, and Argonaute on the transcriptome of Schizosaccharomyces pombe (fission yeast). The clr mutants derepressed similar subsets of genes, many of which also became transcriptionally activated in cells that were exposed to environmental stresses such as nitrogen starvation. Many genes that were repressed by the Clr proteins clustered in extended regions close to the telomeres. Surprisingly few genes were repressed by both the silencing and RNAi machineries, with transcripts from centromeric repeats and Tf2 retrotransposons being notable exceptions. We found no correlation between repression by RNAi and proximity to LTRs, and the wtf family of repeated sequences seems to be repressed by histone deacetylation independent of RNAi. Our data indicate that the RNAi and Clr proteins show only a limited functional overlap and that the Clr proteins play more global roles in gene silencing.
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Project description:The molecular and cellular basis of novelty is an active area of research in evolutionary biology. Until very recently, the vast majority of cellular phenomena were so difficult to sample that cross-species studies of biochemistry were rare and comparative analysis at the level of biochemical systems was almost impossible. Recent advances in systems biology are changing what is possible, however, and comparative phylogenetic methods that can handle this new data are wanted. Here, we introduce the term "phylogenetic latent variable models" (PLVMs, pronounced "plums") for a class of models that has recently been used to infer the evolution of cellular states from systems-level molecular data, and develop a new parameterization and fitting strategy that is useful for comparative inference of biochemical networks. We deploy this new framework to infer the ancestral states and evolutionary dynamics of protein-interaction networks by analyzing >16,000 predominantly metazoan co-fractionation and affinity-purification mass spectrometry experiments. Based on these data, we estimate ancestral interactions across unikonts, broadly recovering protein complexes involved in translation, transcription, proteostasis, transport, and membrane trafficking. Using these results, we predict an ancient core of the Commander complex made up of CCDC22, CCDC93, C16orf62, and DSCR3, with more recent additions of COMMD-containing proteins in tetrapods. We also use simulations to develop model fitting strategies and discuss future model developments.
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Project description:BackgroundPerturbations in cell-cell interactions are a key feature of cancer. However, little is known about the systematic effects of cell-cell interaction on global gene expression in cancer.ResultsWe used an ex vivo model to simulate tumor-stroma interaction by systematically co-cultivating breast cancer cells with stromal fibroblasts and determined associated gene expression changes with cDNA microarrays. In the complex picture of epithelial-mesenchymal interaction effects, a prominent characteristic was an induction of interferon-response genes (IRGs) in a subset of cancer cells. In close proximity to these cancer cells, the fibroblasts secreted type I interferons, which, in turn, induced expression of the IRGs in the tumor cells. Paralleling this model, immunohistochemical analysis of human breast cancer tissues showed that STAT1, the key transcriptional activator of the IRGs, and itself an IRG, was expressed in a subset of the cancers, with a striking pattern of elevated expression in the cancer cells in close proximity to the stroma. In vivo, expression of the IRGs was remarkably coherent, providing a basis for segregation of 295 early-stage breast cancers into two groups. Tumors with high compared to low expression levels of IRGs were associated with significantly shorter overall survival; 59% versus 80% at 10 years (log-rank p = 0.001).ConclusionIn an effort to deconvolute global gene expression profiles of breast cancer by systematic characterization of heterotypic interaction effects in vitro, we found that an interaction between some breast cancer cells and stromal fibroblasts can induce an interferon-response, and that this response may be associated with a greater propensity for tumor progression.
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Project description:Gene co-expression networks capture biological relationships between genes and are important tools in predicting gene function and understanding disease mechanisms. We show that technical and biological artifacts in gene expression data confound commonly used network reconstruction algorithms. We demonstrate theoretically, in simulation, and empirically, that principal component correction of gene expression measurements prior to network inference can reduce false discoveries. Using data from the GTEx project in multiple tissues, we show that this approach reduces false discoveries beyond correcting only for known confounders.
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Project description:RNA interference (RNAi) is reported here for the first time for Biomphalaria glabrata, the snail intermediate host for the human parasite Schistosoma mansoni. The fibrinogen-related protein 2 (FREP2) gene, normally expressed at increased levels following exposure to digenetic trematode parasites, such as S. mansoni or Echinostoma paraensei, was targeted for knockdown. Double-stranded RNA (dsRNA) corresponding to specific regions of the FREP2 gene was introduced into snails by direct injection into the hemolymph, 2 days prior to exposure to trematodes, or added to co-cultures of B. glabrata embryonic (Bge) cells and E. paraensei sporocysts. After introduction of FREP2 dsRNA, expression levels of FREP2 were significantly reduced, to 20-30% of control values. In addition, we were able to disrupt expression of the house-keeping myoglobin gene, further confirming the feasibility of RNAi for B. glabrata. Cross-reactivity in RNAi has not been observed either among four FREP gene subfamilies or between FREP2 and myoglobin. Establishment of RNAi techniques in B. glabrata provides an important tool for clarifying the function of genes believed to play a role in host-parasite interactions, specifically between B. glabrata and its trematode parasites, including S. mansoni.
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Project description:The improvement of the agricultural and wine-making qualities of the grapevine (Vitis vinifera) is hampered by adherence to traditional varieties, the recalcitrance of this plant to genetic modifications, and public resistance to genetically modified organism (GMO) technologies. To address these challenges, we developed an RNA virus-based vector for the introduction of desired traits into grapevine without heritable modifications to the genome. This vector expresses recombinant proteins in the phloem tissue that is involved in sugar transport throughout the plant, from leaves to roots to berries. Furthermore, the vector provides a powerful RNA interference (RNAi) capability of regulating the expression of endogenous genes via virus-induced gene-silencing (VIGS) technology. Additional advantages of this vector include superb genetic capacity and stability, as well as the swiftness of technology implementation. The most significant applications of the viral vector include functional genomics of the grapevine and disease control via RNAi-enabled vaccination against pathogens or invertebrate pests.
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Project description:We here used the technology of RNA interference and cDNA microarrays to reconstruct a network between genes known to be disregulated in ER-positive breast cancer diseases. Therefor single genes of high importance were silenced and the effect of this pertubation was measured with cDNA microarrays Keywords: network_reconstruction_RNAi human ER-positive breast cancer cell line was cultivated as described and transfection with chemically synthesized siRNAs was performed according to standard HiPerFect transfection protocol by Qiagen (Hilden, Germany) At least 4 cDNA-microarrays were hybridized in dye-swap method for the silencing of every gene of interest. To minimize off-target effects we used at least two different siRNAs per gene.
| S-ECPF-GEOD-7033 | biostudies-other
Project description:ObjectiveTo identify the tissue expression patterns and biological pathways enriched in term amniotic fluid cell-free fetal RNA by comparing functional genomic analyses of term and second-trimester amniotic fluid supernatants.MethodsThis was a prospective whole genome microarray study comparing eight amniotic fluid samples collected from women at term who underwent prelabor cesarean delivery and eight second-trimester amniotic fluid samples from routine amniocenteses. A functional annotation tool was used to compare tissue expression patterns in term and second-trimester samples. Pathways analysis software identified physiologic systems, molecular and cellular functions, and upstream regulators that were significantly overrepresented in term amniotic fluid.ResultsThere were 2,871 significantly differentially regulated genes. In term amniotic fluid, tissue expression analysis showed enrichment of salivary gland, tracheal, and renal transcripts as compared with brain and embryonic neural cells in the second trimester. Functional analysis of genes upregulated at term revealed pathways that were highly specific for postnatal adaptation such as immune function, digestion, respiration, carbohydrate metabolism, and adipogenesis. Inflammation and prostaglandin synthesis, two key processes involved in normal labor, were also activated in term amniotic fluid.ConclusionsTranscriptomic analysis of amniotic fluid cell-free fetal RNA detects fetal maturation processes activated in term pregnancy. These findings further develop the concept of amniotic fluid supernatant as a real-time gene expression "summary fluid" and support its potential for future studies of fetal development.
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