Proteins widely believed to protect against aging can actually cause oxidative damage in mammalian brain cells. [The] findings suggest that the proteins can have both proaging and protective functions, depending on the circumstances, the researchers said.
"Sirtuins are very important proteins," said Valter Longo of the University of Southern California, Los Angeles. "Overexpression can protect in some cases, and in other cases, it may do the opposite. It has to do with the fact that they do so many things."
Longo urges caution to those developing SirT1-boosting drugs intended for human consumption.
" [Such drugs] could have beneficial effects for certain diseases, but again, these proteins do a lot of things," he said. "I would say the idea that there is a conserved action of sirtuins to cause major life span extension - the foundations for that are weak or very weak. Until we have more data to show that chronic treatment to increase SirT1 activity does not do damage, I don't think it's a good idea."
Metabolism is very complex, and the sirtuin story is a good illustration of that point. What might have seemed straightforward a few years back, at the opening of serious movement towards commercial calorie restriction mimetics, is anything but.