Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Transcription profiling of mouse C2C12 myotubes treated overnight with 500 uM palmitate or 1% bovine serum albumin control to identify mediators of obesity-linked reductions in PGC-1

ABSTRACT: To identify mediators of obesity-linked reductions in PGC-1, we tested the effects of cellular nutrients in C2C12 myotubes. While overnight exposure to high insulin, glucose, glucosamine, or amino acids had no effect, saturated fatty acids (FA) potently reduced PGC-1a and b mRNA expression. Experiment Overall Design: Cell culture - Mouse C2C12 myoblasts (ATCC, Manassas, VA) were maintained in Dulbecco's modified Eagle's medium (DMEM) supplemented with 20% fetal bovine serum (Invitrogen), at a confluency of 60-70%. To initiate differentiation, cells were allowed to reach 100% confluency and medium was changed to DMEM containing 2% horse serum (Invitrogen) and changed every 2 days. Full differentiation, with myotube fusion and spontaneous twitching, was observed at 5 days. Fatty acid stock preparation - Fatty acids were dissolved in 0.1 N sodium hydroxide (final concentration 100 mM) at 65 degrees C for 2 hours and then complexed with 10% fatty acid-free BSA, yielding a final stock of 5 mM. Three replicates for each fatty-acid. Microarray analysis - RNA was isolated as described from C2C12 myotubes treated overnight with 500 uM palmitate or 1% BSA, and cRNA was synthesized. 10 mg of cRNA were hybridized to Affymetrix mouse 430A 2.0 arrays. Intensity values were quantified using MAS 5.0 software. MAPPFinder (www.genmapp.org) was used to integrate expression data with known pathways. Transcription profiling of mouse C2C12 myotubes treated overnight with 500 uM palmitate or 1% BSA to identify mediators of obesity-linked reductions in PGC-1.

ORGANISM(S): Mus musculus

SUBMITTER: Sarah Crunkhorn

PROVIDER: E-GEOD-6766 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Peroxisome proliferator activator receptor gamma coactivator-1 expression is reduced in obesity: potential pathogenic role of saturated fatty acids and p38 mitogen-activated protein kinase activation.

Crunkhorn Sarah S Dearie Farrell F Mantzoros Christos C Gami Hiral H da Silva Wagner S WS Espinoza Daniel D Faucette Ryan R Barry Kristen K Bianco Antonio C AC Patti Mary Elizabeth ME

The Journal of biological chemistry 20070406 21

Peroxisome proliferator activator receptor-gamma coactivator 1 (PGC-1) is a major candidate gene for diabetes-related metabolic phenotypes, contributing to decreased expression of nuclear-encoded mitochondrial genes in muscle and adipose tissue. We have demonstrated that muscle expression of PGC-1alpha and -beta is reduced in both genetic (Lep(ob)/Lep(ob)) and acquired obesity (high fat diet). In C57BL6 mice, muscle PGC-1alpha expression decreased by 43% (p < 0.02) after 1 week of a high fat die ...[more]

PMID: 17416903

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Project description:Obesity is becoming increasingly widespread in developed countries, and is often associated with heart diseases and diabetes. Elevated levels of plasma free fatty acids are a biochemical hallmark of obesity. Unlike plants and bacteria, mammals cannot utilize fatty acids to generate glucose because of the lack of glyoxylate shunt enzymes. Instead, fatty acids are used for energy storage, and their utilization is regulated at multiple levels ranging from hormonal to metabolic ensuring that glucose is preferentially oxidized before fatty acids. Here we designed a synthetic gene-metabolic circuit to alter the intracellular signaling and metabolic pathways that control fatty acid metabolism. By introducing the Escherichia coli glyoxylate shunt enzymes, isocitrate lyase (AceA) and malate synthase (AceB), into the mitochondria of human hepatocytes, we demonstrated that fatty acid utilization is preferentially increased while glucose uptake is significantly reduced. This bacterial pathway diverts signal metabolites (citrate, acetyl-CoA, and malonyl-CoA) that inhibits fatty acid uptake and provides an additional channel for fatty acid utilization. Remarkably, the hepatocytes readily adapted to the synthetic circuit by a series of global transcriptional and post-translational changes in metabolic and signal transduction pathways that further advanced our design objective. This systems approach illustrates the logic of the synergistic interaction between metabolism and signal transduction. The ready acceptance of this non-native pathway by hepatocytes suggests the plasticity of liver metabolism and opens a possibility for the synthetic approach in regulating human metabolism. Experiment Overall Design: Wild type (WT) human hepatocyte HepG2 and HepG2 cells stably transfected with pBudaceAB (designated ACE), a vector containing isocitrate lyase and malate synthase from E. coli, were analyzed after 24hour exposure to palmitate. Cells were seeded at 70% confluency in 10cm plates with DMEM growth media augmented with 300uM palmitate. After 24hours, total RNA was harvested and hybrized to Affymetrix HG_U133A 2.0 GeneChips. Data was processed using GCOS 1.2 software. Experiment Overall Design: 2 WT biological replicates and 2 ACE biological replicates were analyzed. Experiment Overall Design:

Project description:The transcriptional coactivator peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1Î±) is a chief activator of the mitochondrial and metatolic program in skeletal muscle (skm) and prevents atrophy. Here we tested whether PGC-1Î± overexpression could restructure the transcriptome and metabolism of cultured human skeletal myotubes, which display an athropic phenotype. An oligonucleotide microarray analysis was used to reveal PGC-1Î± effects on the whole transcriptome, and the possible impact on fuel metabolism reprogramming was examined. Fifty-three different genes displayed changed expression levels in response to PGC-1Î±: 42 upregulated and 11 downregulated. Main associations of gene ontologies (GO) for the upregulated genes were mitochondrial components and processes and this correlated with an increase in COX activity, an indicator of mitochondrial content. Palmitate and lactate oxidation to CO2 was enhanced, but not glucose oxidation. The other most significant GO associations of upregulated genes were chemotaxis and cytokine activity, and accordingly, several cytokines, including IL8, CXCL6, CCL5 and CCL8, were within top induced genes. Among the most regulated genes were also potential metabolic regulators of fatty acid and glucose storage. FITM1/FIT1 induction was associated with an increased number of lipid droplets with smaller area, while triglyceride levels were modestly increased in oleate-incubated cells. Downregulation of CALM1, the calcium-modulated Î´ subunit of phosphorylase kinase, was linked to inactivation of glycogen phosphorylase and greater accumulation of glycogen. The most upregulated gene was PVALB, which is also related to calcium signaling. In conclusion, only the deficient mitochondrial transcriptional program of cultured myotubes is rescued by PGC-1Î±. New PGC-1Î± gene targets and pathways arise, some of which may mediate its activating effects in processes such as lipid and carbohydrate storage and angiogenesis. 6 samples from 3 different skeletal muscle cell cultures were used: 3 were transfected with adenovirus containing PGC-1aplha and 3 with adenovirus containing GFP (control). The 3 PGC-1alpha samples were compared against the control samples.

Dataset Information

Transcription profiling of mouse C2C12 myotubes treated overnight with 500 uM palmitate or 1% bovine serum albumin control to identify mediators of obesity-linked reductions in PGC-1

Publications

Peroxisome proliferator activator receptor gamma coactivator-1 expression is reduced in obesity: potential pathogenic role of saturated fatty acids and p38 mitogen-activated protein kinase activation.

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