Project description:Caloric restriction (CR) without malnutrition appears to mitigate many detrimental effects of aging, in particular the age-related decline in skeletal muscle mitochondrial function. Although the mechanisms responsible for this protective effect remain unclear, CR is commonly believed to increase mitochondrial biogenesis; a concept that is now demanding closer scrutiny. Here we show that lifelong CR in mice prevents age-related loss of mitochondrial function, measured in isolated mitochondria and permeabilized muscle fibers. We find that these beneficial effects of CR occur without increasing mitochondrial abundance. Furthermore, whole-genome expression profiling and large-scale proteomic surveys revealed expression patterns inconsistent with increased mitochondrial biogenesis. These observations, combined with lower protein synthesis rates support an alternative hypothesis that CR preserves mitochondrial function not by increasing mitochondrial biogenesis, but rather by decreasing mitochondrial oxidant emission, increasing antioxidant scavenging, thereby minimizing oxidative damage to cellular components. Cross-sectional comparison of skeletal muscle from young (8mo), old (24mo) and old caloric restricted mice, obtained from the colony maintained on behalf of the National Institute on Aging.
Project description:Caloric restriction (CR) without malnutrition appears to mitigate many detrimental effects of aging, in particular the age-related decline in skeletal muscle mitochondrial function. Although the mechanisms responsible for this protective effect remain unclear, CR is commonly believed to increase mitochondrial biogenesis; a concept that is now demanding closer scrutiny. Here we show that lifelong CR in mice prevents age-related loss of mitochondrial function, measured in isolated mitochondria and permeabilized muscle fibers. We find that these beneficial effects of CR occur without increasing mitochondrial abundance. Furthermore, whole-genome expression profiling and large-scale proteomic surveys revealed expression patterns inconsistent with increased mitochondrial biogenesis. These observations, combined with lower protein synthesis rates support an alternative hypothesis that CR preserves mitochondrial function not by increasing mitochondrial biogenesis, but rather by decreasing mitochondrial oxidant emission, increasing antioxidant scavenging, thereby minimizing oxidative damage to cellular components.
Project description:Astrocytes are key cells in brain aging, helping neurons to undertake healthy aging or otherwise letting them enter into a spiral of neurodegeneration. We aimed to characterize astrocytes cultured from senescence-accelerated prone 8 (SAMP8) mice, a mouse model of brain pathological aging, along with the effects of caloric restriction, the most effective rejuvenating treatment known so far. Analysis of the transcriptomic profiles of SAMP8 astrocytes cultured in control conditions and treated with caloric restriction serum was performed using mRNA microarrays. A decrease in mitochondrial and ribosome mRNA, which was restored by caloric restriction, confirmed the age-related profile of SAMP8 astrocytes and the benefits of caloric restriction. An amelioration of antioxidant and neurodegeneration-related path- ways confirmed the brain benefits of caloric restriction. Studies of oxidative stress and mitochondrial function demonstrated a reduction of oxidative damage and partial improvement of mito- chondria after caloric restriction. In summary, caloric restriction showed a significant tendency to normalize pathologically aged astrocytes through the activation of pathways that are protective against the age-related deterioration of brain physiology. Key words: astrocytes; caloric restriction; mitochondria; oxidative stress; RNA microarrays; SAMP8.
Project description:Astrocytes are key cells in brain aging, helping neurons to undertake healthy aging or otherwise letting them enter into a spiral of neurodegeneration. We aimed to characterize astrocytes cultured from senescence-accelerated prone 8 (SAMP8) mice, a mouse model of brain pathological aging, along with the effects of caloric restriction, the most effective rejuvenating treatment known so far. Analysis of the transcriptomic profiles of SAMP8 astrocytes cultured in control conditions and treated with caloric restriction serum was performed using mRNA microarrays. A decrease in mitochondrial and ribosome mRNA, which was restored by caloric restriction, confirmed the age-related profile of SAMP8 astrocytes and the benefits of caloric restriction. An amelioration of antioxidant and neurodegeneration-related path- ways confirmed the brain benefits of caloric restriction. Studies of oxidative stress and mitochondrial function demonstrated a reduction of oxidative damage and partial improvement of mito- chondria after caloric restriction. In summary, caloric restriction showed a significant tendency to normalize pathologically aged astrocytes through the activation of pathways that are protective against the age-related deterioration of brain physiology. Key words: astrocytes; caloric restriction; mitochondria; oxidative stress; RNA microarrays; SAMP8. Primary cultures enriched in astrocytes were obtained from cerebral cortical tissue from 2-day-old SAMP8 and SAMR1 mice. Astrocyte cultures were established and experiments were routinely carried out after 21 days in culture. Established astrocyte cultures of both SAMR1 and SAMP8 consisted of 85-90% astrocytes, 10-15% microglia and 0.1-1% oligodendroglia. Sera from rats subjected to ad libitum (AL) diet and to CR were obtained as described for the establishment of the CR in vitro model (de Cabo et al., 2003). Serum was heat inactivated at 56°C prior to use in astrocyte culture experiments. Treatment in vitro was performed by adding 10% volume CR or AL serum onto the astrocyte culture medium for 48 h, the cells were harvested and RNA was extracted for the microarray studies. Three biological replicates for each condition were done and RNA was extracted for the microarray studies. Please note that SAM models were developed from AKR/J by Kyoto University. Five litters with severe senescence were selected to further propagate and examine these characteristics. Litters that showed normal aging were selected as a senescence-resistant series (R-series). The genetic background of the SAM mice became suspect after the pathological findings were different from the AKR/J mouse. Each SAM model is genetically different. Each SAM colony was acquired by Harlan by Takeda Chemical Ltd. in 2002. And here is the link to the company site. http://www.harlan.com/products_and_services/research_models_and_services/research_models/sam_inbred_mice/samp8tahsd.hl
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:A gradual decline in renal function occurs even in healthy aging individuals. In addition to aging per se, concurrent metabolic syndrome and hypertension, which are common in the aging population, can induce mitochondrial dysfunction, and inflammation, which collectively contribute to age-related kidney disease. Here we studied the role of the nuclear hormone receptors, the estrogen related receptors (ERRs) in regulation of age-related mitochondrial dysfunction and inflammation. ERRs are decreased in aging human and mouse kidneys and preserved in aging mice with lifelong caloric restriction (CR). Our studies identified ERRs as important modulators of age-related mitochondrial dysfunction and inflammation. ERRα, ERRβ, and ERRγ levels are decreased in the aging kidney. Remarkably, only a 4-week treatment of 21-month-old mice with the pan ERR agonist reversed the age-related increases in albuminuria and podocyte loss, mitochondrial dysfunction and inflammatory cytokines, including the cGAS-STING and STAT3 signaling pathways. A 3-week treatment of 21-month-old mice with a STING inhibitor reversed the increases in inflammatory cytokines and the senescence marker p21 but also unexpectedly reversed the age-related decreases in PGC-1α, ERRα, mitochondrial complexes and Mcad expression.
Project description:The effects of caloric restriction (CR) on glucose homeostasis and metabolic function differ between males and females. To investigate if hepatic function contributes to these sex differences, we collected liver samples from male and female C57BL/6NCrl mice that were fed ad libitum (AL) or underwent caloric restriction (CR; receiving 70% of daily AL intake) from 9-13 weeks of age. Livers were then analysed by bulk RNA-seq.
Project description:Aging is the progressive decline in organismal function that leads to an increased risk of multiple diseases and mortality. The molecular basis of this decline is unknown. Using quantitative PCR for mitochondrial mRNA from multiple tissues from the same animals, we found that the rate of change in mouse mitochondrial expression is tissue-specific, with cardiac expression declining early (8-10 months), adipose expression declining late (25-30 months), and no change in kidney or skin. In cardiac tissue, mitochondria-derived mRNA levels declined more slowly than nuclear encoded mRNAs, suggesting a potential dysregulation. These changes were independent of alteration in mitochondrial number, as measured by quantitative PCR of mitochondrial DNA and citrate synthase activity. We found no change in the variability between mitochondrial mRNA levels with age, suggesting that the changes are not due to random dysregulation at the level of gene expression. Caloric restriction (CR), a lifespan-extending intervention proposed to act through mitochondrial biogenesis, delayed the decline in both cardiac and adipose mitochondrial mRNA levels of F344 rats. CR caused an increase in citrate synthase activity but did not alter mitochondrial DNA content, indicating increased translation or reduced turnover of mitochondrial proteins. These results demonstrate that mitochondrial gene expression changes with age are not coupled to mitochondrial number, are likely to be regulated, and are governed by tissue-specific processes. These findings indicate that aging is neither a programmed organism-wide change orchestrated in a top-down fashion nor a product of random dysregulation of gene expression but that tissue-specific factors may independently control aging in different organ compartments. Keywords: aging Cardiac ventricle total RNA from 10 young (4-6 month) and 10 young (25-28 month) mice were compared.