High-throughput small molecule screening reveals Nrf2-dependent and -independent pathways of cellular stress resistance.

Aging is the dominant risk factor for most chronic diseases. Development of antiaging interventions offers the promise of preventing many such illnesses simultaneously. Cellular stress resistance is an evolutionarily conserved feature of longevity. Here, we identify compounds that induced resistance to the superoxide generator paraquat (PQ), the heavy metal cadmium (Cd), and the DNA alkylator methyl methanesulfonate (MMS). Some rescue compounds conferred resistance to a single stressor, while others provoked multiplex resistance. Induction of stress resistance in fibroblasts was predictive of longevity extension in a published large-scale longevity screen in Caenorhabditis elegans, although not in testing performed in worms and flies with a more restricted set of compounds. Transcriptomic analysis and genetic studies implicated Nrf2/SKN-1 signaling in stress resistance provided by two protective compounds, cardamonin and AEG 3482. Small molecules identified in this work may represent attractive tools to elucidate mechanisms of stress resistance in mammalian cells.

Fibroblasts From Longer-Lived Species of Primates, Rodents, Bats, Carnivores, and Birds Resist Protein Damage.

Species differ greatly in their rates of aging. Among mammalian species life span ranges from 2 to over 60 years. Here, we test the hypothesis that skin-derived fibroblasts from long-lived species of animals differ from those of short-lived animals in their defenses against protein damage. In parallel studies of rodents, nonhuman primates, birds, and species from the Laurasiatheria superorder (bats, carnivores, shrews, and ungulates), we find associations between species longevity and resistance of proteins to oxidative stress after exposure to H(2)O(2) or paraquat. In addition, baseline levels of protein carbonyl appear to be higher in cells from shorter-lived mammals compared with longer-lived mammals. Thus, resistance to protein oxidation is associated with species maximal life span in independent clades of mammals, suggesting that this cellular property may be required for evolution of longevity. Evaluation of the properties of primary fibroblast cell lines can provide insights into the factors that regulate the pace of aging across species of mammals.

Rapamycin-mediated lifespan increase in mice is dose and sex dependent and metabolically distinct from dietary restriction.

Rapamycin, an inhibitor of mTOR kinase, increased median lifespan of genetically heterogeneous mice by 23% (males) to 26% (females) when tested at a dose threefold higher than that used in our previous studies; maximal longevity was also increased in both sexes. Rapamycin increased lifespan more in females than in males at each dose evaluated, perhaps reflecting sexual dimorphism in blood levels of this drug. Some of the endocrine and metabolic changes seen in diet-restricted mice are not seen in mice exposed to rapamycin, and the pattern of expression of hepatic genes involved in xenobiotic metabolism is also quite distinct in rapamycin-treated and diet-restricted mice, suggesting that these two interventions for extending mouse lifespan differ in many respects.

Resistance of skin fibroblasts to peroxide and UV damage predicts hearing loss in aging mice.

Those mice whose skin-derived primary fibroblast cell lines resist lethal injury induced by hydrogen peroxide or UV light show lower age-related decline in hearing. Skin cell lines may provide an easily accessible surrogate index of intrinsic stress resistance that varies among individuals and influences the pace of neurosensory decline in aging mice.

Genomic profiling of restraint stress-induced alterations in mouse T lymphocytes.

DNA damage-, DNA repair-, and apoptosis-related gene expression in CD3(+) T lymphocytes of BALB/c mice subjected to 2-h restraint stress were compared to that in CD3(+)T lymphocytes from control mice. Using targeted cDNA arrays, significant increases in expression of genes serving as sensors of DNA damage, including MSH genes and RAD53, were observed. GADD45g, a gene responsible for regulating cell cycle arrest and apoptosis, was significantly induced; as was Pura, a gene involved in cell proliferation. These data suggest that, at the molecular level, stress activates genes responsible for priming the T cell to either undergo apoptosis or proliferation.