April 8, 2004

Even stress, in moderation, is good

By Megan Fellman

We’ve often heard that red wine and dark chocolate in moderation can be good for you. Now it appears that a little stress may be beneficial, too.

Richard I. Morimoto, John Evans Professor of Biology and co-author of the paper, said, “Sustained stress definitely is not good for you, but it appears that an occasional burst of stress or low levels of stress can be very protective.”

Northwestern scientists have shown that elevated levels of special protective proteins that respond to stress in a cell (known as molecular chaperones) promote longevity. Acute stress triggers a cascading reaction inside cells that results in the repair or elimination of misfolded proteins, prolonging life by preventing or delaying cell damage.

The findings were published by Molecular Biology of the Cell, a publication of the American Society for Cell Biology.

“Sustained stress definitely is not good for you, but it appears that an occasional burst of stress or low levels of stress can be very protective,” said Richard I. Morimoto, John Evans Professor of Biology, who co-authored the paper with lead author James F. Morley, a graduate student in Morimoto’s lab. “Brief exposure to environmental and physiological stress has long-term benefits to the cell because it unleashes a great number of molecular chaperones that capture all kinds of damaged and misfolded proteins.”

Stressors also include elevated temperatures, oxygen stress, bacterial and viral infections, and exposure to toxins such as heavy metals, all of which challenge the environment of the cell. A master protein called heat shock factor senses the stress and responds by turning on the genes that encode molecular chaperones.

Proteins are basic components of all living cells. To do its job properly, each protein first must fold itself into the proper shape. In this process, the protein is assisted by molecular chaperones that function to prevent misfolding, or, in the case of already misfolded proteins, to detect them and prevent their further accumulation. Mutations or environmental stress enhances protein damage. If misfolded or damaged proteins accumulate beyond a certain critical point, neurodegenerative diseases such as Huntington’s, Parkinson’s, Alzheimer’s and Lou Gehrig’s diseases can result.