Researchers here show that increased levels of a mitochondrial sirtuin, sirt4, can modestly extend life in flies. Unfortunately, this sort of manipulation of metabolism – connected to nutrient sensing, mitochondrial activity, and calorie restriction – scales poorly as the life span of species increases. Short-lived species are comparatively sensitive to periodic lack of resources, and exhibit a sizable extension of life span in response to a lack of nutrients. This improves their prospects for current survival and then later reproduction when nutrients are once more available. Longer-lived species – such as our own – have for much of their evolutionary history enjoyed life spans far longer than any common period of famine, however. Thus we have a much smaller response to periods of reduced dietary nutrients, at least when considered in terms of additional healthy life, even though short-term measures of improved health are somewhat similar to those found in short-lived species.
“We show that Sirt4 is responsible for regulating both lifespan and metabolism in an organism, and specifically that it coordinates the metabolic response to fasting. We also demonstrate that overexpressing the gene for Sirt4 can extend lifespan of
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