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: Scientists work to save endangered desert mammal

add to favorites email to friend print save as pdf

Related Stories

Partial solar eclipse over the U.S. on Thursday, Oct. 23

32 minutes ago

People in most of the continental United States will be in the shadow of the Moon on Thursday afternoon, Oct. 23, as a partial solar eclipse sweeps across the Earth. For people looking through sun-safe filters, from Los Angeles, ...

Apple starts iPhone 6 sales in key China market

35 minutes ago

Apple began selling its latest iPhone in China Friday, nearly a month after other major territories due to a licence delay by regulators, but it faces a tough battle with rivals led by Samsung in the crucial ...

Recommended for you

Scientists work to save endangered desert mammal

9 minutes ago

Amargosa voles, small rodents that inhabit rare marshes of the Mojave Desert, have faced dire circumstances in recent years. Loss of habitat, extreme drought and climate change brought this subspecies of ...

Sex-loving, meat-eating reptiles have shorter lives

1 hour ago

The health risks and benefits of vegetarianism have long been discussed in relation to the human diet, but newly published research reveals that it's definitely of benefit to the reptile population. That, ...

US charges safari owners with illegal rhino hunts

13 hours ago

Two South African men were charged Thursday by the US government with conspiracy to sell illegal rhinoceros hunts to American hunters, money laundering and secretly trafficking in rhino horns.

User comments : 0