Protein May Be Key to Aging

Scientists have identified a stretchy protein they say is associated with the ravages of aging and chronic diseases such as emphysema.

The protein, known as fibulin-5, is critical to the development of elastic fibers that stabilize the outside of cell walls, keeping skin tight and lungs and blood vessels pliable.

Two studies into the function of fibulin-5 appear in the Jan. 10 issue of Nature.

In separate experiments, researchers at the University of Texas Southwestern Medical Center in Dallas and the University of California, San Diego specially bred mice that lack fibulin-5.

Without the protein, the mice in both studies survived into adulthood. However, they developed very loose skin and abnormal tissues, including twisted aortas and other blood vessels.

Among the diseases they developed was emphysema, in which lung tissues loose elasticity and cannot expand and contract, limiting the amount of oxygen that is transferred to the bloodstream.

Nearly 2 million Americans suffer from emphysema, usually caused by smoking. Tobacco smoke triggers a release of enzymes that attack elastic fibers in the lungs and destroy air sacs.

Scientists are seeking a way to repair or regenerate the elastic fibers to treat diseases, as well as to improve skin tone and turn back the clock on aging.

``We believe that fibulin-5 will be an indispensable ingredient in the recipe,'' said molecular biologist Tomoyuki Nakamura, lead author of the UCSD study.

Scientists who were not involved in mouse studies said more research is needed to precisely determine fibulin-5's role. They said it is unlikely that fibulin-5 acts alone; other proteins are likely to be involved, too.

``There is no indication that abnormalities in fibulin-5 necessarily play a role in the pathophysiology of human emphysema or stiffening of the arteries with aging,'' said Edward Lakatta, chief of cardiovascular science at the National Institute of Aging.

Previous research has identified additional proteins that provide elasticity to the smooth muscle linings of blood vessels and other tissues. Loss of those proteins has been associated with diseases such as hardening of the arteries.

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