SirT1 inhibition reduces IGF-I/IRS-2/Ras/ERK1/2 signaling and protects neurons |
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Authors: | Li Ying Xu Wei McBurney Michael W Longo Valter D |
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Affiliation: | 1Neuroscience Program, University of Southern California, Los Angeles, CA 90089-2520, USA;2Andrus Gerontology Center and Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-0191, USA;3Ottawa Health Research Institute, Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada |
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Abstract: | Sirtuins are known to protect cells and extend life span, but our previous studies indicated that S. cerevisiae Sir2 can also increase stress sensitivity and limit life-span extension. Here we provide evidence for a role of the mammalian Sir2 ortholog SirT1 in the sensitization of neurons to oxidative damage. SirT1 inhibition increased acetylation and decreased phosphorylation of IRS-2; it also reduced activation of the Ras/ERK1/2 pathway, suggesting that SirT1 may enhance IGF-I signaling in part by deacetylating IRS-2. Either the inhibition of SirT1 or of Ras/ERK1/2 was associated with resistance to oxidative damage. Markers of oxidized proteins and lipids were reduced in the brain of old SirT1-deficient mice, but the life span of the homozygote knockout mice was reduced under both normal and calorie-restricted conditions. These results are consistent with findings in S. cerevisiae and other model systems, suggesting that mammalian sirtuins can play both protective and proaging roles. |
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Keywords: | HUMDISEASE SIGNALING |
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