Project description:Metformin is a type 2 diabetes medication which extends life span across species when given from young adulthood onwards; late life effects of metformin are not well understood. Here we used C. elegans to investigate the outcome of metformin treatment initiated late in life. We found that, contrary to young age administration, old age metformin treatment interferes with energy homeostasis and shortens life span by aggravating age-associated mitochondrial dysfunction. Nematode mutants defective in mitochondrial respiration, mitochondrial biogenesis and mitochondrial quality control were highly susceptible to metformin killing already at young age while insulin receptor deficient nematodes carrying healthier mitochondria were protected from late life metformin toxicity. In the mammalian cell culture model of replicative senescence metformin killing correlated with loss of mitochondrial membrane potential and strong reduction of systemic ATP levels. Reduced ATP levels and depletion of lipid stores consistent with energy deficit were observed also in nematodes following late life metformin treatment. At the molecular level young animals responded to metformin by inducing adaptive stress responses and longevity-assurance pathways while old nematodes demonstrated a protein expression signature consistent with lipid turnover and energy deficit. Ectopic ATP supplementation was sufficient to alleviate metformin toxicity in human skin fibroblasts highlighting the key contribution of energy deficit to the detrimental effect of metformin. Also, co-exposure with rapamycin, known to stabilize cellular ATP levels under conditions of mitochondrial failure, significantly reduced metformin-inflicted lethality in both cells and old animals. In summary we uncovered a novel negative synergism between metformin treatment and mitochondrial dysfunction which gains importance late in life and may limit therapeutic benefits of metformin for older patients; these side effects can partially be overcome by co-treatment with agents stabilizing cellular ATP levels such as rapamycin.
Project description:Late-life intervention with a soy-enriched diet attenuated age-dependent changes in renal structure and dysfunction in male Fischer 344 rats.
Project description:Studies of aging and longevity are revealing how diseases that shorten life can be controlled to improve the quality of life and lifespan itself. Two strategies under intense study to accomplish this goal are rapamycin treatment and calorie restriction. New strategies are being discovered including one that uses low-dose myriocin treatment. Myriocin inhibits the first enzyme in sphingolipid synthesis in all eukaryotes and we showed recently that low-dose myriocin treatment increases yeast lifespan at least in part by down-regulating the sphingolipid-controlled Pkh1/2-Sch9 (ortholog of mammalian S6 kinase) signaling pathway. Here we show that myriocin treatment has global influences and modulates the evolutionarily conserved Snf1/AMPK, PKA and TORC1 signaling pathways to enhance yeast lifespan. These extensive affects of myriocin rival those of rapamycin and calorie restriction. Our studies in yeast along with other studies in mammals reveal the potential of myriocin or related compounds to lower the incidence of age-related diseases in humans. No-myriocin-treated cells and myriocin-treated cells; three biological replicates in each treatment
| E-GEOD-41362 | biostudies-arrayexpress
Project description:Suppression of the gut microbiome with broad-spectrum antibiotics reverses age-related arterial dysfunction
Project description:Rapamycin extends life span in mice, but it remains unclear if this compound also delays mammalian aging. Here, we present results from a comprehensive large-scale assessment of a wide rage of structural and functional aging phenotypes in mice. Rapamycin extended life span but showed few effects on a large number of systemic aging phenotypes, suggesting that rapamycin's effects on aging are largely limited to the regulation of age-related mortality and carcinogenesis. Total RNA obtained from 2-4 male mice of each analysed group (25 weeks old controls, 25 month old controls, 25 month old rapamycin treated)
Project description:Rapamycin extends life span in mice, but it remains unclear if this compound also delays mammalian aging. Here, we present results from a comprehensive large-scale assessment of a wide rage of structural and functional aging phenotypes in mice. Rapamycin extended life span but showed few effects on a large number of systemic aging phenotypes, suggesting that rapamycin's effects on aging are largely limited to the regulation of age-related mortality and carcinogenesis.
Project description:Studies of aging and longevity are revealing how diseases that shorten life can be controlled to improve the quality of life and lifespan itself. Two strategies under intense study to accomplish this goal are rapamycin treatment and calorie restriction. New strategies are being discovered including one that uses low-dose myriocin treatment. Myriocin inhibits the first enzyme in sphingolipid synthesis in all eukaryotes and we showed recently that low-dose myriocin treatment increases yeast lifespan at least in part by down-regulating the sphingolipid-controlled Pkh1/2-Sch9 (ortholog of mammalian S6 kinase) signaling pathway. Here we show that myriocin treatment has global influences and modulates the evolutionarily conserved Snf1/AMPK, PKA and TORC1 signaling pathways to enhance yeast lifespan. These extensive affects of myriocin rival those of rapamycin and calorie restriction. Our studies in yeast along with other studies in mammals reveal the potential of myriocin or related compounds to lower the incidence of age-related diseases in humans.
Project description:Purpose: Despite demonstrating that the overall effect of long-term rapamycin-treatment is overwhelmingly positive in aging skeletal muscle, we observed muscle-specificity in the responsiveness to rapamycin, leading us to hypothesize that the primary drivers of age-related muscle loss and therefore effective intervention strategies may differ between muscles. To address this question and dissect the key signaling nodes associated with mTORC1-driven muscle aging, we created a comprehensive multi-muscle gene expression atlas in adult, sarcopenic and rapamycin-treated mice using RNA-seq. Methods: To examine the impact of long-term rapamycin treatment, male C57BL/6 mice were fed encapsulated rapamycin incorporated into a standardized AIN93M diet at 42 ppm (i.e. mg per kg of food), corresponding to a dose of ~4 mg·kg-1·day-1, from 15- to 30-months of age. This dose of rapamycin has been shown to extend lifespan maximally in male C57BL/6 mice. We performed RNA-seq on gastrocnemius (GAS), tibialis anterior (TA), triceps brachii (TRI) and soleus (SOL) muscles from each of six mice for 10m, 30m and 30mRM groups. The four muscle types were chosen to encompass fore- and hindlimb locations (e.g. TRI and GAS); slow and fast contraction properties (e.g. SOL and GAS); anterior and posterior positioning (e.g. TA and GAS) and the extent of protection by rapamycin (TA and TRI: protected; SOL: partiallly protected; GAS: not protected). Results: Age-related gene expression changes were remarkably consistent across the four different muscles, varying only in magnitude. Despite having the smallest age-related muscle loss of the four muscles, TA had the strongest age-related gene expression response which was associated with an increased reinnervation response. Despite the strong between-muscle commonality of age-related changes, gene expression responses to prolonged rapamycin treatment differed substantially between muscles. Rapamycin partially reversed many age-related changes in mRNA expression in the TA and TRI, but not in SOL or GAS muscle. Principle component analysis (PCA) showed that rapamycin had common 'anti-aging' effects on all muscles, while also exerting muscle-specific pro-aging effects on muscles not protected by rapamycin. Conclusions: Sustained, muscle fiber-specific mTORC1 activity drives sarcopenia-like gene expression programs, and the hyperactive mTORC1 seen in sarcopenic muscle may therefore contribute to sarcopenia.
Project description:Somatic mutations of ASXL1 are frequently detected in age-related clonal hematopoiesis (CH). However, how ASXL1 mutations drive CH remains elusive. Using knockin (KI) mice expressing a C-terminally truncated form of ASXL1-mutant (ASXL1-MT), we examined the influence of ASXL1-MT on physiological aging in hematopoietic stem cells (HSCs). HSCs expressing ASXL1-MT display competitive disadvantage after transplantation. Nevertheless, in genetic mosaic mouse model, they acquire clonal advantage during aging, recapitulating CH in humans. Mechanistically, ASXL1-MT cooperates with BAP1 to deubiquitinate and activate AKT. Overactive Akt/mTOR signaling induced by ASXL1-MT results in aberrant proliferation and dysfunction of HSCs associated with age-related accumulation of DNA damage. Treatment with an mTOR inhibitor rapamycin ameliorates aberrant expansion of the HSC compartment as well as dysregulated hematopoiesis in aged ASXL1-MT KI mice. Our findings suggest that ASXL1-MT provokes dysfunction of HSCs, whereas it confers clonal advantage on HSCs over time, leading to the development of CH.