Project description:Metabolic dysfunction is one of the main symptoms of Werner syndrome (WS); however, the underlying mechanisms remain unclear. Here, we report that loss of WRN accelerates adipogenesis at an early stage both in vitro (stem cells) and in vivo (zebrafish). Moreover, WRN depletion causes a transient upregulation of late-stage of adipocyte-specific genes at an early stage.
Project description:BackgroundMetabolic dysfunction is one of the main symptoms of Werner syndrome (WS); however, the underlying mechanisms remain unclear. Here, we report that loss of WRN accelerates adipogenesis at an early stage both in vitro (stem cells) and in vivo (zebrafish). Moreover, WRN depletion causes a transient upregulation of late-stage of adipocyte-specific genes at an early stage.MethodsIn an in vivo study, we generated wrn-/- mutant zebrafish and performed histological stain and Oil Red O staining to assess the fat metabolism. In an in vitro study, we used RNA-seq and ATAC-seq to profile the transcriptional features and chromatin accessibility in WRN depleted adipocytes. Moreover, we performed ChIP-seq to further study the regulatory mechanisms of metabolic dysfunction in WS.ResultsOur findings show that mechanistically WRN deficiency causes SMARCA5 upregulation. SMARCA5 is crucial in chromatin remodeling and gene regulation. Additionally, rescuing WRN could normalize SMARCA5 expression and adipocyte differentiation. Moreover, we find that nicotinamide riboside (NR) supplementation restores adipocyte metabolism in both stem cells and zebrafish models.ConclusionsOur findings unravel a new mechanism for the influence of WRN in the early stage of adipogenesis and provide a possible treatment for metabolic dysfunction in WS. These data provide promising insights into potential therapeutics for ageing and ageing-related diseases.
Project description:Werner Syndrome (WS) is an autosomal recessive disorder characterized by premature aging due to mutations of the WRN gene. A classical sign in WS patients is short stature, but the underlying mechanisms are not well understood. Here we report that WRN is indispensable for chondrogenesis, which is the engine driving the elongation of bones and determines height.
Project description:Werner Syndrome (WS) is an autosomal recessive disorder characterized by premature aging due to mutations of the WRN gene. A classical sign in WS patients is short stature, but the underlying mechanisms are not well understood. Here we report that WRN is indispensable for chondrogenesis, which is the engine driving the elongation of bones and determines height.
Project description:Werner syndrome (WS) is a human adult progeroid syndrome caused by loss-of-function mutations in the WRN RECQ helicase gene. We analyzed mRNA and miRNA expression in fibroblasts from WS patients and in fibroblasts depleted of WRN protein in order to determine the role of WRN in transcription regulation, and to identify genes and miRNAs that might drive WS disease pathogenesis. Genes altered in WS cells participate in cellular growth, proliferation and survival; in tRNA charging and in oncogenic signaling; and in connective tissue and developmental networks. Genes down-regulated in WS cells were highly enriched in Gquadruplex (G4) DNA motifs, indicating G4 motifs are physiologic substrates for WRN. In contrast, there was a remarkable, coordinate up-regulation of nearly all of the cytoplasmic tRNA synthetases and of genes associated with the senescence-associated secretory phenotype (SASP). These results identify canonical pathways that may drive the pathogenesis of Werner syndrome and associated disease risks.
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 3 months old Wrn mutant mice treated with 0.4% vitamin C to untreated 3 months old Wrn mutant mice. Microarray analyses were performed on the liver tissues of 3 months old mice. Four independent biological replicates of this experiment (untreated Wrn mutant mice vs vitamin C treated Wrn mutant mice) were carried out on four 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 3 months old Wrn mutant mice treated with 0.4% vitamin C to untreated 3 months old Wrn mutant mice.
Project description:Metabolic dysfunction is a primary feature of Werner syndrome (WS), a human premature aging disease caused by mutations in the gene encoding the Werner (WRN) DNA helicase. WS patients exhibit severe metabolic phenotypes, but the underlying mechanisms are not understood, and whether the metabolic deficit can be targeted for therapeutic intervention has not been determined. Here we report impaired mitophagy and depletion of NAD+, a fundamental ubiquitous molecule, in WS patient samples and WS invertebrate models. WRN regulates transcription of a key NAD+ biosynthetic enzyme nicotinamide nucleotide adenylyltransferase 1 (NMNAT1). NAD+ repletion restores NAD+ metabolic profiles and improves mitochondrial quality through DCT-1 and ULK-1-dependent mitophagy. At the organismal level, NAD+ repletion remarkably extends lifespan and delays accelerated aging, including stem cell dysfunction, in C. elegans and Drosophila melanogaster models of WS. Our findings suggest that accelerated aging in WRN syndrome is mediated by impaired mitochondrial function and mitophagy, and that bolstering cellular NAD+ levels counteracts WS phenotypes.
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.