www.newscientist.com 16 August 2008 | NewScientist | 9

SMART FACT: The soft top of the smart fortwo

cabriolet can be raised or lowered while

travelling at up to 70 mph.

>>

To raise or lower the soft top on a typical

cabriolet you must slow to less than 30 mph

or stop completely.

www.newscientist.com/thinksmart

“DE-CLUTTER your life” is a mantra of many a self-help book, but de-clutter your internal organs instead and you could prevent the harmful effects of ageing. In mice at least, ensuring the liver stays clean and tidy has kept that organ as good as new, even in whiskery old-timers.

In healthy young cells, the removal of old proteins relies on “chaperone molecules” that attach to the proteins and then dock with enzyme-filled compartments called lysosomes, which dismantle and recycle them. But as we age, this clean-up machinery starts to fail, allowing damaged proteins to accumulate.

To see if this protein build-up is responsible for the functional decline of ageing organs, Ana Maria Cuervo and colleagues at the Albert Einstein College of Medicine of Yeshiva University in New York, engineered mice with an extra copy of the gene that codes for the receptor protein that enables the chaperone to dock with the lysosome. They then left the mice to age for 22 to 26 months – equivalent to 80 years in humans.

When the team analysed the livers of these elderly modified mice, they found that they worked just as well as the livers of normal young mice, and much better than those of normal old

mice, indicating that preventing protein accumulation also prevents age-related function loss (Nature Medicine, DOI: 10.1038/nm.1851).

How might this be used to benefit humans? We can’t yet easily add genes to the cells of living people but Cuervo says that finding a drug that protects the existing receptor proteins would have the same effect as adding a

gene that produces new protein. “We are starting drug

screening with the idea of looking for compounds that stabilise this particular receptor in the lysosomes,” she says.

Better still would be to prolong

the life of the receptor protein without a drug, perhaps through diet. “We know that the stability of this protein is related to changes in lipids,” says Cuervo. So a low-fat diet might help.

As the same mechanism for protein clearance is used all over the body, Cuervo hopes the finding could also be applied to other organs. In Alzheimer’s and Parkinson’s disease, for example, an abnormal amount of protein builds up in brain cells. Improving the clearance of these proteins might delay the onset of symptoms, she says.

Thomas von Zglinicki who studies cellular gerontology at the University of Newcastle, UK, says that while previous researchers have induced premature ageing in animals, this study is important because the researchers have actually prevented the symptoms of ageing. Tamsin Osborne ●

How old mice kept their livers forever young

“The livers of the elderly genetically modified mice worked just as well as the livers of normal young mice”