Project description:Werner syndrome (WS) is a rare disorder characterized by the premature onset of a number of age-related diseases. The gene responsible for WS is believed to be involved in different aspects of transcription, replication, and/or DNA repair. The poly(ADP-ribose) polymerase-1 (PARP-1) enzyme is also involved in DNA repair and is known to affect transcription of several genes. In this study, we examined the expression profile of cells lacking the normal function of either or both enzymes. All mutant cells exhibited altered expression of genes normally responding to oxidative stress. Interestingly, more than 58% of misregulated genes identified in double mutant cells were not altered in cells with either the Wrn or PARP-1 mutation alone. Consequently, the impact on gene expression profile when both Wrn and PARP-1 are mutated was greater than a simple addition of individual mutant genotype. In addition, double mutant cultured cells showed major misregulation of genes involved in apoptosis, cell cycle control, embryonic development, metabolism, and signal transduction. More importantly, in vivo analyses of double mutant mice have confirmed the increased apoptosis and the developmental defects in embryos as well as the major increase in intracellular phosphorylation and oxidative DNA damage in adult tissues. They also exhibited a progressive increase in oxidative stress with age. Thus, a major result of this study is that changes in expression of several genes and physiological functions identified in vitro were confirmed in mouse embryonic and adult tissues. Experiment Overall Design: Microarray analyses were performed on cell cultures at the second passage (10 population doublings). For each genotype, asynchronously dividing cells derived from three healthy 15.5 day embryos from one litter were pooled at the second passage and cytoplasmic RNA was extracted. Cytoplasmic RNA was used in these experiments to avoid contamination with heterogeneous nuclear RNA and genomic DNA. (Note that DNAse treatment was also applied to all samples). This pool of RNA was labeled sample number 1 for each genotype. Pooling of embryonic cells was performed to minimize the effect of inter-individual biological differences. A second pool of embryonic cells was also created from a separate dam (second litter) for each genotype (called samples number 2). This strategy allowed obtaining samples in duplicate for each genotype. The cRNA from wild type cells were synthesized with Cy-5 labeled nucleotides and cRNAs from Wrn mutant, PARP-1 null, and PARP-1 null/Wrn mutant cells were synthesized with Cy-3 labeled nucleotides. Hybridization was performed on Mouse Agilent 60-mer Oligo Microarray chips by mixing wild type labeled cRNA (baseline expression levels) with either Wrn mutant, PARP-1 null, or PARP-1 null/Wrn mutant cRNA. Hybridization experiments were done in duplicates.

Project description:Werner syndrome (WS) is a rare disorder characterized by the premature onset of a number of age-related diseases. The gene responsible for WS is believed to be involved in different aspects of transcription, replication, and/or DNA repair. We generated a mouse model with a deletion in the helicase domain of the murine WRN homologue that recapitulates most of the WS phenotypes including an abnormal hyaluronic acid excretion, higher reactive oxygen species (ROS) levels, increased genomic instability and cancer incidence resulting in a 10-15% decreased life span expectancy. In addition, WS patients and Wrn mutant mice show hallmarks of a metabolic syndrome including premature visceral obesity, hypertriglyceridemia, insulin-resistant diabetes type 2 and associated cardiovascular diseases. In this study, we compared the expression profile of liver tissues from 9 months old Wrn mutant and wild type animals. Gene set enrichment analysis of the microarray data indicated that Wrn mutant mice exhibited down-regulation of genes normally decreased in several transgenic mouse models of hepatoma and during caloric restriction. Wrn mutant mice also altered the expression of genes involved in inflammation as well as in glutathione and xenobiotic metabolisms. These results indicate that Wrn mutant mice respond to the observed oxidative stress by altering the necessary pathways to survive. Vitamin C supplementation rescued the life span expectancy of Wrn mutant mice and reversed several age-related abnormalities in adipose, cardiac, and liver tissues, genomic integrity and inflammatory status. Finally, gene set enrichment analyses revealed that vitamin C decreased genes normally up regulated in human WS fibroblasts and cancers and it increased genes involved in tissue injury response and adipocyte dedifferentiation in obese mice. Experiment Overall Design: Microarray analyses were performed on the liver tissues of 9 months old mice. Four independent biological replicates of this experiment (wild type vs Wrn mutant or wild type vs vitamin C treated mutant mice) were carried out with a dye swap on two replicates of each genotype.

Project description:Werner syndrome (WS) is a rare disorder characterized by the premature onset of a number of age-related diseases. The gene responsible for WS is believed to be involved in different aspects of transcription, replication, and/or DNA repair. We generated a mouse model with a deletion in the helicase domain of the murine WRN homologue that recapitulates most of the WS phenotypes including an abnormal hyaluronic acid excretion, higher reactive oxygen species (ROS) levels, increased genomic instability and cancer incidence resulting in a 10-15% decreased life span expectancy. In addition, WS patients and Wrn mutant mice show hallmarks of a metabolic syndrome including premature visceral obesity, hypertriglyceridemia, insulin-resistant diabetes type 2 and associated cardiovascular diseases. In this study, we compared the expression profile of liver tissues from 9 months old Wrn mutant treated with a standard diet supplemented with 0.04% resveratrol and wild type animals fed with standard diet only. Resveratrol is a calorie restriction mimetic. Gene set enrichment analysis of the microarray data indicated that reseveratrol-treated Wrn mutant mice exhibited down-regulation of genes normally decreased in several transgenic mouse models of hepatoma. In addition, resvratrol-treated Wrn mutant mice also exhibited a decrease in the expression of genes involved fatty acid metabolism and PPAR signaling pathways. Resvratrol-treated Wrn mutant mice also increased the expression of genes involved in steroid and cholesterol biosynthesis, xenobiotic metabolisms as well as inflammation. Finally, resveratrol improved insulin-resistance and the hyperglycemia but had no impact on dyslipidemia and mean life span of Wrn mutant mice. Microarray analyses were performed on the liver tissues of 9 months old mice. Four independent biological replicates of this experiment (wild type vs resveratrol treated Wrn helicase mutant mice) were carried out with a dye swap on two replicates of each genotype.

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Differential expression of genes in cells mutant for Wrn and/or PARP-1 compared to wild type cells

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