Unknown,Transcriptomics,Genomics,Proteomics

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Cerebellar gene expression profiles of mouse models for Rett Syndrome reveal MeCP2 targets

ABSTRACT: Background MeCP2, methyl-CpG-binding protein 2, binds to methylated cytosines at CpG dinucleotides, as well as to unmethylated DNA, and affects chromatin condensation. MECP2 mutations in females lead to Rett syndrome, a neurological disorder characterized by developmental stagnation and regression, loss of purposeful hand use and speech, stereotypic hand movements, deceleration of brain growth, autonomic dysfunction and seizures. Most mutations occur de novo during spermatogenesis. Located at Xq28, MECP2 is subject to X inactivation, and affected females are mosaic. Rare hemizygous males suffer from a severe congenital encephalopathy. Methods To identify pathways mis-regulated by MeCP2 deficiency, microarray-based global gene expression studies were carried out on cerebellum of Mecp2 mutant mice. We compared transcript levels in mutant/wildtype male sibs of two different MeCP2-deficient mouse models at 2, 4 and 8 weeks of age. Increased transcript levels were evaluated by real-time quantitative RT-PCR. Chromatin immunoprecipitation assays were used to document in vivo MeCP2 binding to promoter regions of candidate target genes. Results In the mutants, several hundred genes showed altered expression levels. Twice as many were increased than decreased, and only 27 genes were differentially expressed at more than one time point. The number of misregulated genes was 30% lower in mice with an exon 3 deletion (Mecp2tm1.1Jae) than in mice with a larger deletion (Mecp2tm1.1Bird). Between the mutants, few misregulated genes overlapped at each time point. Real-time quantitative RT-PCR assays validated increased transcript levels for four genes: Irak1, interleukin-1 receptor-associated kinase 1; Fxyd1, phospholemman, associated with Na, K-ATPase; Reln, encoding reelin, an extracellular signaling molecule essential for neuronal lamination and synaptic plasticity; and Gtl2/Meg3, an imprinted maternally expressed non-translated RNA that serves as a host gene for C/D box snoRNAs and microRNAs. Chromatin immunoprecipitation assays documented in vivo MeCP2 binding to promoter regions of Fxyd1, Reln, and Gtl2. Conclusions Transcriptional profiling of cerebellum failed to detect significant global changes in Mecp2-mutant mice. Increased transcript levels of Irak1, Fxyd1, Reln, and Gtl2 may contribute to the neuronal dysfunction in MeCP2-deficient mice and individuals with Rett syndrome. Our data provide testable hypotheses for future studies of the regulatory or signaling pathways that these genes act on. A genetic modification design type is where an organism(s) has had genetic material removed, rearranged, mutagenized or added, such as knock out. Computed

ORGANISM(S): Mus musculus

SUBMITTER: Charandle Jordan

PROVIDER: E-GEOD-8774 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Cerebellar gene expression profiles of mouse models for Rett syndrome reveal novel MeCP2 targets.

Jordan ChaRandle C Li Hong Hua HH Kwan Helen C HC Francke Uta U

BMC medical genetics 20070620

<h4>Background</h4>MeCP2, methyl-CpG-binding protein 2, binds to methylated cytosines at CpG dinucleotides, as well as to unmethylated DNA, and affects chromatin condensation. MECP2 mutations in females lead to Rett syndrome, a neurological disorder characterized by developmental stagnation and regression, loss of purposeful hand movements and speech, stereotypic hand movements, deceleration of brain growth, autonomic dysfunction and seizures. Most mutations occur de novo during spermatogenesis. ...[more]

PMID: 17584923

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Project description:These 95 arrays are the basis for Figure 2 of our manuscript "An interferon-response induced by tumor-stroma interaction in a subset of human breast cancers". Abstract:Background Communication between different cell types is a cardinal feature of multi-cellular organisms and perturbations in these 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. Methods and Findings We used an ex vivo culture 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. The picture of heterotypic interaction effects that emerged from this analysis is complex, reflecting the variation in signaling capacities and responsiveness of the involved cells. A frequent and prominent response to epithelial-mesenchymal interaction was an induction of interferon-response genes, observed in 4 of the 7 breast cancer cell lines in response to co-culture with fibroblasts, but not in normal mammary epithelial cells. In response to close contact with these breast cancer cells, the fibroblasts secreted type I interferons, which, in turn, induced expression of the IRGs in the tumor cells. Immunohistochemical analysis of human breast cancer tissues showed that STAT1, the key transcriptional activator of the interferon-response genes, and itself an IRG, was expressed in a subset of the cancers, with a striking pattern of elevated expression in the cancer cells in contact with, or close proximity to, the tumor stroma ? paralleling the response seen in our ex vivo model. In vivo, expression of the interferon-response genes was remarkably coherent, providing a basis for segregation of the 295 early-stage breast cancers into two groups. Tumors with high expression levels (n=161) of IRG were associated with significantly shorter overall survival; 59 % at 10 years versus 80% for tumors with low interferon-response gene expression levels (n=134) (log-rank p=0.001). Conclusion Our results suggest 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. Set of arrays organized by shared biological context, such as organism, tumors types, processes, etc. Computed

Project description:Patient Selection: Three hospitals were involved in the study: Dong Thap Provincial and An Giang Provincial hospitals, both located in the Mekong Delta Region of Vietnam where most of the Typhoid patients were admitted, and the Hospital for Tropical Diseases, Ho Chi Minh City, where the malarial patients were admitted. Infection status of each patient was determined by blood culture for the Typhoid patients and by microscopic examination of stained thick and thin peripheral-blood slides for the patients suspected of having Malaria. Patients with blood cultures positive for S. Typhi or S. enterica serovar Paratyphi A (S. Paratyphi A) (samples designated ST) or peripheral blood smears positive for Plasmodium falciparum or Plasmodium vivax (samples designated PF) were consented and enrolled in the study. A total of 28 S. Typhi positive patients and one S. Paratyphi A positive patient were enrolled in the first phase of the study and a further 9 S. Typhi and one S. Paratyphi A positive patient were enrolled in the second phase. Nine patients with Malaria caused by P. falciparum and one caused by P. vivax were enrolled. Sixteen uninfected healthy individuals (samples designated HC) were also enrolled in the study (one sample each). The Typhoid patients were randomly chosen to receive either Azithromycin or Gatifloxicin (20mg/kg/day for 7 days) antibiotics. Uncomplicated malaria patients were treated for 3 days with Artekin (dihydroartemisinin with piperaquine phosphate). Venous blood (2.5ml) was collected for total RNA extraction into PaxGene RNA collection tubes (Qiagen) at various times. The first sample (T1) was taken immediately on admission or entry into the study, then samples were collected, 3 (T3), 6-9 (T9 for Typhoid, T7 for Malaria), and 28-45 (T28) days following entry into the study and an average of 9 months (T9M) later. The PaxGene tubes were stored at 4degC until RNA was extracted as per the manufacturers instructions. Purified RNA was shipped on dry ice to Stanford University, CA for use in Microarray analyses. Microarrays: Experimental and reference samples (Human Universal RNA reference {Stratagene}) were amplified using the MessageAmp II aRNA Kit (Ambion) as per the manufacturer's instructions. Four micrograms amplified RNA was labeled through indirect incorporation of Cy5 (experimental) and Cy3 (reference) dyes (protocols can be found at http://cmgm.stanford.edu/pbrown/protocols/index.html). The labeled probes were then mixed and hybridized to Stanford Human cDNA arrays with 42 K features. Arrays were scanned using a Genepix 4000A laser scanner and data extracted with Genepix Pro Software version 5.1 (Axon Instruments). The data were then uploaded into the Stanford Microarray Database (SMD). A disease state experiment design type is where the state of some disease such as infection, pathology, syndrome, etc is studied. Compound Based Treatment: Drugs used for treatment Disease State: Malaria, Typhoid or Healthy Controls Keywords: disease_state_design Complex

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Cerebellar gene expression profiles of mouse models for Rett Syndrome reveal MeCP2 targets

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Cerebellar gene expression profiles of mouse models for Rett syndrome reveal novel MeCP2 targets.

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