Unknown,Transcriptomics,Genomics,Proteomics

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Transcription profiling of rat Myasthenia gravis model, diaphragm, extensor digitorum longus and extraocular muscles

ABSTRACT: gene expression profile in diaphragm (DIA), extensor digitorum longus (EDL) and extraocular (EOM) muscles of rats with actively induced experimentally acquired MG (EAMG) using Affymetrix rat RAE230 gene chip. Experiment Overall Design: Total RNA was obtained with TRIzol (Invitrogen Carlsbad, CA) following the manufacturers recommended protocol. Tissues from 3 animals were combined into each RNA sample to decrease inter-subject variability. RNA pellets were cleaned by RNasey kits and resuspended at 1 Î¼g RNA/Î¼l DEPC-treated water and 5 ug was used in a reverse transcription reaction (SuperScript II; Life Technologies, Rockville, MD) to generate first strand cDNA. Double strand cDNA was synthesized and used in an in vitro transcription (IVT) reaction to generate biotinylated cRNA. Fragmented cRNA (15 ug) was used in a 300 ul hybridization cocktail containing herring sperm DNA and BSA as carrier molecules, spiked IVT controls, and buffering agents. A 200 ul aliquot of this cocktail was used for hybridization to Affymetrix rat REA230 (Santa Clara, CA) microarrays for 16 hrs at 45o C. The manufacturerâs standard post-hybridization wash, double-stain, and scanning protocols used an Affymetrix GeneChip Fluidics Station 400 and a Hewlett Packard Gene Array scanner. Experiment Overall Design: Microarray data analysis Experiment Overall Design: Raw data from microarray scans were analyzed with Affymetrix GCOS 2.0. GCOS evaluates sets of perfect match (PM) and mismatch (MM) probe sequences to obtain both hybridization signal values and present/absent calls for each transcript. Microarrays were scaled to the same target intensity and pairwise comparisons were made between experimental and control samples. Comparisons the one-sided Wilcoxonâs signed rank test to estimate âincrease/no change/ decreaseâ difference calls for each pair-wise comparison. Transcripts defined as differentially regulated met the criteria of: (a) consistent increase/decrease call across 7 out of 9 replicate comparisons, based upon Wilcoxonâs signed rank test (algorithm assesses probe pair saturation, calculates a p value and determines increase, decrease, or no change calls) and (b) the average fold difference â¥ 2.0. Data were visualized as a hierarchical dendrogram generayed on computer (Genespring software,ver 7.2; Silicon Genetics, Redwood city, CA). Annotation was done according to Affymetrix NetAffyx Gene Ontology database.

ORGANISM(S): Rattus norvegicus

SUBMITTER: Bendi Gong

PROVIDER: E-GEOD-11465 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:In muscle, reactive oxygen species (ROS) generation increases with strenuous activity, chronic unloading, and inflammatory stimuli; skeletal muscle function is very sensitive to ROS; and there are redox-sensitive signaling pathways. Using myogenic cell cultures, we asked whether hydrogen peroxide (H2O2) induces adaptive changes in skeletal muscle gene expression. H2O2 downregulated or failed to induce antioxidant or apoptotic genes in the myotubes. Instead, H2O2 changed the expression of genes for cytosolic and mitochondrial enzymes, and upregulated inflammatory mediators. Finally, H2O2 had a mostly inhibitory effect on the expression of many transcription factors. The results indicate that mild oxidative stress may induce an adaptive response in skeletal muscle without antioxidant upregulation or apoptosis. Experiment Overall Design: Cell Culture: Experiment Overall Design: C2C12 myoblasts (ATCC, Rockville, MD) were cultured in DMEM supplemented with 10% fetal calf serum at 37°C in 5% CO2. Myoblast differentiation was initiated by switching to differentiation medium (DMEM supplemented with 2% heat-inactivated horse serum) and allowed to continue for 96 hrs. Differentiated myotubes were treated for 2 hours with H2O2 (Sigma-Aldrich, St. Louis, MO) 0, 1, 10, 100, or 1000 uM in DMEM supplemented with 0.5% heat-inactivated horse serum. Experiment Overall Design: cDNA microarrays: Experiment Overall Design: Total RNA was obtained from treated C2C12 myotubes with TRIzol reagent (Invitrogen, Carlsbad, CA) following the manufacturer's recommended protocol.Oligonucleotide microarray studies with Affymetrix Mouse Genome 430A gene chips (n=20 chips) were conducted as described earlier. Microarrays were washed and stained with a streptavidin-bound marker and scanned. Data were analyzed with Affymetrix Microarray Suite 5.0 software. Only genes with consistent absent/present calls in all four independent replicates per group were considered for further analysis. Treatment comparisons were crossed so that each H2O2 sample was compared to each control. The software uses the one-sided Wilcoxon's signed rank test to estimate increase/no change/ decrease difference calls for each pair-wise comparison. Only difference calls consistent in all pair-wise comparisons and with average changes > 1.75 were considered significant, resulting in a conservative list of genes with changed expression levels. Functional classification of genes was based on an extensive literature review.

Project description:Some of the most common neurodegenerative disorders have a strong association with aging. Curiously, these conditions tend to involve specific areas of the central and peripheral nervous system, at least initially. For example, amyotrophic lateral sclerosis preferentially targets spinal motor neurons and spares oculomotor neurons. This suggests that aging has divergent effects on brain stem and spinal cord, a factor that may explain differential susceptibility to certain neurodegenerative disorders. Therefore, for this study we asked whether aging induces a change in the evolution of the transcriptome of oculomotor nucleus (OMN) throughout the lifespan which would be different than that of the spinal cord aging. Age induced a transcriptome shift to a pattern consistent with inflammation/immune response in both OMN and spinal cord. However, the response was more dramatic in the spinal cord. On the other hand, age repressed genes coding ion channels and transporters in OMN and cytoskeletal proteins in the spinal cord. The results indicate that OMN and spinal cord transcriptomes change differently with age. The results give an initial glimpse of how tissue-specific gene expression patterns may underlie the differential susceptibility to age-related neuromuscular dysfunction. Experiment Overall Design: Total RNA was obtained with TRIzol (Invitrogen Carlsbad, CA) following the manufacturers recommended protocol. Tissues from 4 animals were combined into each RNA sample to decrease inter-subject variability. Biotinylated cRNA samples were hybridized to Affymetrix Rat Genome RA230 gene chips (n=18 chips) described previously [McMullen et al. 2004]. Microarrays were washed and stained with a streptavidin-bound marker and scanned. Data were analyzed with Affymetrix Microarray Suite 5.0 software. Only genes with consistent absent/present calls in all four independent replicates per group were considered for further analysis. Comparisons used the 6-mo transcriptome as the baseline and the one-sided Wilcoxonâ??s signed rank test to estimate â??increase/no change/ decreaseâ?? difference calls for each pair-wise comparison. Only difference calls consistent in all pair-wise comparisons and with average changes > 1.70 were considered significant, resulting in a conservative list of genes with changed expression levels. Functional classification of genes was based on an extensive literature review.

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Transcription profiling of rat Myasthenia gravis model, diaphragm, extensor digitorum longus and extraocular muscles

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