http://www.digitaljournal.com/article/258437

Scientists stop aging process in liver

Posted Aug 11, 2008 by Chris V. Thangham
New York scientists have demonstrated how to halt the aging process in an organ for the first time in a mouse study. The organ functions well with age.
Researchers at the Albert Einstein College of Medicine at Yeshiva University in New York City have stopped the aging process in the liver of mice for the first time. The liver functions as well as they did when the mice were younger.
Associate professor Ana Maria Cuervo, one of the main researchers in this study, blocked the aging process in mice livers by stopping the build-up of harmful proteins inside the organ’s cells.
When people age, the livers become less efficient in getting rid of this unhealthy proteins as a result toxic materials build up inside the livers and cause the various diseases such as Alzheimer’s, Parkinson’s and other neuro-degenerative disorders.
The researchers say by cleaning of the damaging proteins in the liver, the body functions well with age and could delay or prevent the onset of neural disorders.
Cuervo told ABC Australia: Many of these diseases are due to 'misbehaving' or damaged proteins that accumulate in neurons. By preventing this decline in protein clearance, we may be able to keep these people free of symptoms for a longer time.
The scientists found that livers in genetically modified mice 22 to 26 months old (equivalent to octogenarians in human years) cleaned blood as efficiently as those in mice a quarter their age. This was in contrast to the livers in normal mice in a control group, which failed with the aging process.
Cuervo said whatever they did for livers can also be extended for other organs and could extend life as well.
In a human body, the cleaning of proteins is done as follows:
In healthy organisms, a surveillance system inside cells called chaperone-mediated autophagy (CMA) locates, digests and destroys damaged proteins.
Specialized molecules, the "chaperones", ferry the harmful material to membrane-bound sacs of enzymes within the cells known as lysosomes.
Once the cargo has been "docked", a receptor molecule transfers the protein into the sac, where it is rapidly digested.
With aging, the receptors stop working efficiently and results in a dangerous build-up of harmful proteins, which leads to neural disorders as well as insulin resistance and the inability to metabolize sugars, fats or alcohol.
Cuervo added receptors in genetically modified mice to compensate for the loss of receptors due to aging. She said it was sufficient to maintain a clean liver.
Leading Australian ageing researcher David le Couteur, Professor of Geriatric Medicine at the University of Sydney, is impressed with the study and told ABC Australia: "She has single-handedly shown that lysosome function is a crucial part of the aging process."
He also praised her for finding the role of lysosomal receptors, which helps keep the liver clean of harmful proteins.
Cuervo will be working with pharmaceutical companies to find drugs that will turn the receptors on or add them to compensate for the loss.
She said the cell clearance of harmful proteins can be accomplished with diet also. Previously, research showed how a restricted diet allowed mammals to live longer.