Project description:Calorie restriction is known to extend lifespan among organisms by a debating mechanism underlying nitric oxide-driven mitochondrial biogenesis. We report here that nitric oxide generators including artemisinin, sodium nitroprusside, and L-arginine mimics calorie restriction and resembles hydrogen peroxide to initiate the nitric oxide signaling cascades and to elicit the global antioxidative responses in mice. The large quantities of antioxidant enzymes are correlated with the low levels of reactive oxygen species, which allow the down-regulation of tumor suppressors and accessory DNA repair partners, eventually leading to the compromise of telomere shortening. Accompanying with the up-regulation of kinases, acetylases, and biomarkers, mitochondrial biogenesis occurs with the elevation of adenosine triphosphate levels upon exposure of mouse skeletal muscles to the mimetics of calorie restriction. In conclusion, calorie restriction-triggered nitric oxide provides antioxidative protection and alleviates telomere attrition via mitochondrial biogenesis, thereby maintaining chromosomal stability and integrity, which are the hallmarks of longevity. Six samples were analyzed, in which a control sample was included.
Project description:Calorie restriction is known to extend lifespan among organisms by a debating mechanism underlying nitric oxide-driven mitochondrial biogenesis. We report here that nitric oxide generators including artemisinin, sodium nitroprusside, and L-arginine mimics calorie restriction and resembles hydrogen peroxide to initiate the nitric oxide signaling cascades and to elicit the global antioxidative responses in mice. The large quantities of antioxidant enzymes are correlated with the low levels of reactive oxygen species, which allow the down-regulation of tumor suppressors and accessory DNA repair partners, eventually leading to the compromise of telomere shortening. Accompanying with the up-regulation of kinases, acetylases, and biomarkers, mitochondrial biogenesis occurs with the elevation of adenosine triphosphate levels upon exposure of mouse skeletal muscles to the mimetics of calorie restriction. In conclusion, calorie restriction-triggered nitric oxide provides antioxidative protection and alleviates telomere attrition via mitochondrial biogenesis, thereby maintaining chromosomal stability and integrity, which are the hallmarks of longevity.
Project description:D-Glucosamine (2-amino-2-deoxy-D-glucose, C.A.S.# 3416-24-8) (GlcN) is a freely available and commonly used dietary supplement possibly promoting cartilage health in humans which also acts as an inhibitor of glycolysis. We here find that GlcN extends C. elegans lifespan by impairing glucose metabolism to activate AMP-activated protein kinase (AMPK/AAK2) leading to increased mitochondrial biogenesis. Consistent with the concept of mitohormesis, this promotes increased formation of mitochondrial reactive oxygen species (ROS) and p38/PMK-1-mediated stress signaling culminating in increased expression of the nematodal amino acid-transporter 1 (aat-1) gene. Ameliorating mitochondrial ROS formation as well as impairment of aat-1-expression abolishes GlcN-mediated lifespan extension in a NRF2/SKN-1-dependent fashion. Notably and unlike other calorie restriction mimetics (CRM) like 2-deoxy-D-glucose (2DG, DOG), GlcN extends lifespan of aging C57BL/6 mice (log-rank: p=0.002; cox regression: p=0.01) similarly paralleled by an induction of mitochondrial biogenesis, increased expression of several murine amino acid transporters, as well as increased amino-acid catabolism. Taken together, GlcN mimics a ketogenic diet to extend healthspan in evolutionary distinct species. 24 samples: 12 mRNA profiles of C.elegans: 6 without GlcN and 6 with GlcN supplementaion; 12 mRNA profiles of M.musculus: 6 without GlcN and 6 with GlcN supplementaion
Project description:D-Glucosamine (2-amino-2-deoxy-D-glucose, C.A.S.# 3416-24-8) (GlcN) is a freely available and commonly used dietary supplement possibly promoting cartilage health in humans which also acts as an inhibitor of glycolysis. We here find that GlcN extends C. elegans lifespan by impairing glucose metabolism to activate AMP-activated protein kinase (AMPK/AAK2) leading to increased mitochondrial biogenesis. Consistent with the concept of mitohormesis, this promotes increased formation of mitochondrial reactive oxygen species (ROS) and p38/PMK-1-mediated stress signaling culminating in increased expression of the nematodal amino acid-transporter 1 (aat-1) gene. Ameliorating mitochondrial ROS formation as well as impairment of aat-1-expression abolishes GlcN-mediated lifespan extension in a NRF2/SKN-1-dependent fashion. Notably and unlike other calorie restriction mimetics (CRM) like 2-deoxy-D-glucose (2DG, DOG), GlcN extends lifespan of aging C57BL/6 mice (log-rank: p=0.002; cox regression: p=0.01) similarly paralleled by an induction of mitochondrial biogenesis, increased expression of several murine amino acid transporters, as well as increased amino-acid catabolism. Taken together, GlcN mimics a ketogenic diet to extend healthspan in evolutionary distinct species.
Project description:Calorie restriction (CR) is a dietary intervention that extends lifespan and healthspan in a variety of organisms. CR improves mitochondrial energy production, fuel oxidation and reactive oxygen species scavenging in skeletal muscle and other tissues, and these processes are thought to be critical to the benefits of CR. PGC-1a is a transcriptional coactivator that regulates mitochondrial function and is induced by CR. Consequently, many of the mitochondrial and metabolic benefits of CR are attributed to increased PGC-1a activity. To test this model for the first time, we examined the metabolic and mitochondrial response to CR in mice lacking skeletal muscle PGC-1a (MKO). Surprisingly, MKO mice demonstrated a normal improvement in glucose homeostasis in response to CR, indicating that skeletal muscle PGC-1a is dispensable for the whole-body benefits of CR. In contrast, gene expression profiling and electron microscopy demonstrated that PGC-1a is required for the full CR-induced increases in mitochondrial gene expression and mitochondrial density in skeletal muscle. These results demonstrate that PGC-1a is a major regulator of the mitochondrial response to CR in skeletal muscle, but surprisingly show that neither PGC-1a nor mitochondrial biogenesis in skeletal muscle are required for the metabolic benefits of CR. Control (FLOX) and PGC-1a skeletal muscle specific knock out (MKO) mice were placed on a control diet [C] or a calorie restriction diet [CR] for 12 weeks. RNA was isolated from TA/EDL muscles for microarray analysis. The following numbers of mice were analyzed from each group: C FLOX: n = 6; C MKO: n = 7; CR FLOX: n = 6; CR MKO: n = 7. Mice were mixed C57/BL6 and 129 background.
Project description:During peri-implantation development, the pluripotent tissue of the early embryo undergoes profound cellular and biochemical reprogramming. These transformations are essential for subsequent development, yet how they are coordinated with the preservation of genome integrity remains poorly understood. Here, we uncover a telomere length checkpoint that is elicited by metabolic remodeling as mouse embryonic stem cells (ESCs) transition from the naïve to formative pluripotent state. We show that the exit of naïve pluripotency is marked by accelerated mitochondrial respiration and de novo lipogenesis, fueling lipid droplet accumulation required for tissue remodeling. Unexpectedly, these acute metabolic shifts trigger transient telomere shortening and activate ZSCAN4, a pluripotency-associated regulator of telomeres, followed by telomere re-elongation as cells adopt a more glycolytic metabolic profile. Our findings reveal a feedback mechanism in which metabolism-induced telomere stress engages ZSCAN4 as a protective response, thereby linking metabolic state to telomere homeostasis during early developmental progression.
Project description:During peri-implantation development, the pluripotent tissue of the early embryo undergoes profound cellular and biochemical reprogramming. These transformations are essential for subsequent development, yet how they are coordinated with the preservation of genome integrity remains poorly understood. Here, we uncover a telomere length checkpoint that is elicited by metabolic remodeling as mouse embryonic stem cells (ESCs) transition from the naïve to formative pluripotent state. We show that the exit of naïve pluripotency is marked by accelerated mitochondrial respiration and de novo lipogenesis, fueling lipid droplet accumulation required for tissue remodeling. Unexpectedly, these acute metabolic shifts trigger transient telomere shortening and activate ZSCAN4, a pluripotency-associated regulator of telomeres, followed by telomere re-elongation as cells adopt a more glycolytic metabolic profile. Our findings reveal a feedback mechanism in which metabolism-induced telomere stress engages ZSCAN4 as a protective response, thereby linking metabolic state to telomere homeostasis during early developmental progression.
Project description:During peri-implantation development, the pluripotent tissue of the early embryo undergoes profound cellular and biochemical reprogramming. These transformations are essential for subsequent development, yet how they are coordinated with the preservation of genome integrity remains poorly understood. Here, we uncover a telomere length checkpoint that is elicited by metabolic remodeling as mouse embryonic stem cells (ESCs) transition from the naïve to formative pluripotent state. We show that the exit of naïve pluripotency is marked by accelerated mitochondrial respiration and de novo lipogenesis, fueling lipid droplet accumulation required for tissue remodeling. Unexpectedly, these acute metabolic shifts trigger transient telomere shortening and activate ZSCAN4, a pluripotency-associated regulator of telomeres, followed by telomere re-elongation as cells adopt a more glycolytic metabolic profile. Our findings reveal a feedback mechanism in which metabolism-induced telomere stress engages ZSCAN4 as a protective response, thereby linking metabolic state to telomere homeostasis during early developmental progression.
Project description:Caloric Restriction in Leptin Deficiency Worsens Myocardial Steatosis: Failure to Upregulate PPAR gamma and Thermogenic Glyecrolipid/Fatty Acid Cycling Growing evidence supports an anti-lipotoxic role for leptin in preventing inappropriate peripheral tissue lipid deposition. Obese, leptin deficient ob/ob mice develop left ventricular (LV) hypertrophy and myocardial steatosis with increased apoptosis and decreased longevity. Here we investigated the cardiac effects of caloric restriction in leptin deficiency. Echocardiography was performed on C57Bl/6 wild-type mice (WT) and 7-month-old ob/ob mice fed ad lib, leptin-repleted (LR-ob/ob), or calorie-restricted (CR-ob/ob) for four weeks. Ventricular tissue was examined by electron microscopy (EM), mitochondrial coupling assay, and microarray expression profiling. LR and CR-ob/ob mice showed decreased body weight, heart weight, and LV wall thickness compared to ad lib ob/ob mice. LV fractional shortening was decreased in ad lib ob/ob mice, but restored to WT levels in LR and CR groups. However, EM revealed severe cardiac steatosis in the CR-ob/ob group compared to only moderate steatosis in ad lib ob/ob . Despite marked cardiac steatosis, CR (like LR) restored mitochondrial coupling to WT levels. CR up-regulated genes associated with oxidative stress and cell death, changes suggestive of cardiac lipotoxicity. LR, but not CR was shown to induce core genes involved in glycerolipid/free fatty acid cycling, a highly thermogenic pathway that can reduce intracellular lipid stores. LR, but not CR up-regulated and restored PGC1 and PPARto wild type levels; CR paradoxically further suppressed cardiac PPAR. Thus, leptin is essential in protecting the heart from lipotoxicity, and the inability to up-regulate the thermogenic glycerolipid/free fatty acid cycling pathway may impair the response of leptin deficient animals to the lipotoxic stress of calorie restriction. 6 month aged ob/ob mice were either leptin repleted with osmotic mini-pumps, calorie restricted to match the caloric intake of the leptin repleted mice, or fed ad lib for one month. 6-8 month C57Bl/6J mice were aged to serve as controls.
Project description:Oxidative stress is a primary cause of cellular senescence and contributes to the pathogenesis of numerous human diseases. Oxidative damage to telomeric DNA is proposed to trigger premature senescence by accelerating telomere shortening. Here we tested this model directly using a precision tool to produce the common base lesion 8-oxoguanine (8oxoG) exclusively at telomeres in human fibroblast and epithelial cells. A single induction of telomeric 8oxoG is sufficient to trigger multiple hallmarks of p53-dependent senescence. Telomeric 8oxoG activates ATM and ATR signaling, and enriches for markers of telomere dysfunction in replicating, but not quiescent cells. Acute 8oxoG production fails to shorten telomeres, but rather generates fragile sites and delayed mitotic DNA synthesis at telomeres, indicative of impaired replication. Based on our results we propose that oxidative stress promotes rapid senescence by producing oxidative base lesions which drive replication-dependent telomere fragility and dysfunction in the absence of shortening and shelterin loss.