Life-extending protein can also have damaging effects on brain cells

Jul 01, 2008

Proteins widely believed to protect against aging can actually cause oxidative damage in mammalian brain cells, according to a new report in the July Cell Metabolism, a publication of Cell Press. 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."

Sirtuins, or Sir2 family proteins, are found in organisms from bacteria to humans. Sir2 controls aging and life span in yeast, the worm C. elegans, and Drosophila fruit flies, earlier studies have shown.

Studies have also implicated Sir2 in the life-extending effects of a calorie restricted diet in some, though not all, organisms. Notably, Longo's lab showed that lack of Sir2 in yeast further extended the life span of calorie-restricted cells.

SirT1, the mammalian version of yeast Sir2, controls numerous physiological processes including glucose metabolism, DNA repair, and cell death, the researchers added. In mammalian cells, SirT1 also controls several stress-response factors.

Now, the researchers show that cultured rat neurons treated with a SirT1 inhibitor more often survived treatment with oxidative stress-inducing chemicals. They further show evidence to explain the mechanism responsible for that effect.

They also found lower oxidative stress levels in the brains of mice without SirT1. However, those SirT1 knockout mice didn't live as long as normal mice do on either a normal or a calorie-restricted diet.

" [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."

Source: Cell Press

Explore further: 'Killer sperm' prevents mating between worm species

add to favorites email to friend print save as pdf

Related Stories

Scalping can raise ticket prices

9 hours ago

Scalping gets a bad rap. For years, artists and concert promoters have stigmatized ticket resale as a practice that unfairly hurts their own sales and forces fans to pay exorbitant prices for tickets to sold-out concerts. ...

Tropical Storm Genevieve forms in Eastern Pacific

11 hours ago

The seventh tropical depression of the Eastern Pacific Ocean formed and quickly ramped up to a tropical storm named "Genevieve." NOAA's GOES-West satellite captured an infrared image of the newborn storm ...

Recommended for you

'Killer sperm' prevents mating between worm species

8 hours ago

The classic definition of a biological species is the ability to breed within its group, and the inability to breed outside it. For instance, breeding a horse and a donkey may result in a live mule offspring, ...

Rare Sri Lankan leopards born in French zoo

11 hours ago

Two rare Sri Lankan leopard cubs have been born in a zoo in northern France, a boost for a sub-species that numbers only about 700 in the wild, the head of the facility said Tuesday.

Japan wraps up Pacific whale hunt

12 hours ago

Japan announced Tuesday that it had wrapped up a whale hunt in the Pacific, the second campaign since the UN's top court ordered Tokyo to halt a separate slaughter in the Antarctic.

Researchers uncover secrets of internal cell fine-tuning

12 hours ago

New research from scientists at the University of Kent has shown for the first time how the structures inside cells are regulated – a breakthrough that could have a major impact on cancer therapy development.

User comments : 0