The trick to keeping organs working well into old age might be taking out the trash, according to a study in Nature Medicine [subscription required]. Researchers led by Ana Maria Cuervo of Yeshiva University in New York have slowed the aging process in the livers of mice by tinkering with a system that recycles the damaged proteins hanging around in a cell. Molecules responsible for "chaperone-mediated autophagy"
handle about 30 percent of the cells' damaged proteins, escorting them to inner cell structures called lysosomes, where enzymes break the proteins down. Studies by Cuervo have shown that the disposal system becomes less efficient as cells grow older. They've also pinpointed the reason for the age-related decline -- a loss of receptors on the surface of the lysosomes that causes a buildup of damaged proteins in the cell
[U.S. News & World Report]. To see whether they could keep the protein recycling system going, Cuervo's team genetically engineered mouse embryos such that their liver cells produced extra copies of the receptors that normally get lost. It worked: When the mice were examined at 22- 26 months of age (equivalent to approximately 80 years old in humans), the liver cells of the GM mice digested and recycled protein far more efficiently than in their normal counterparts of the same age - and, in fact, just as efficiently as in normal six-month old mice [Telegraph]. Humans cells also get worse at recycling proteins as they get older, and transferring this idea to people
could benefit many different human organs, and fight neurodegenerative diseases like Parkinson's and Alzheimer's, according to Cuervo. But how would this work in humans? We can't yet safely add genes to the cells of living people, but Cuervo explains that finding a drug that stops the existing receptor proteins breaking down could have the same effect
[New Scientist]. If humans could clean up our own "logjam" of proteins, Cuervo said, it could help older people lead healthier lives. As is often the case in medicine, however, a simpler, preventative measure might be better—Cuervo says lipids affect the chaperone protein's stability, and a low-fat diet could keep it running smoothly. Image: iStockphoto
