We often think of aging as a slow decline of our bodies and internal organs. But a new study indicates that aging could happen much more quickly, perhaps the result of a switch being suddenly turned off that protects our cells from environmental stresses. Even stranger is that this switch turns off exactly at the time of peak sexual maturity.
The experiments were done in a worm species called C. elegans that is often used as a model for humans. And the research may have implications for understanding human diseases, according to Richard Morimoto, professor of biology at Northwestern University and an author on the paper published today in the journal Molecular Cell. Johnathan Labbadia, a postdoctoral fellow in Morimoto's lab, is the first author of the paper.
"The surprise is that aging is not just a continuum," Morimoto said, "but is very much represented by a precise genetic switch that is thrown at an exact moment. You could imagine all the subsequent events that are a continuum are the consequence of the lack of stress resilience. Muscles don't move as well and the nervous system doesn't respond."
Morimoto said knowing more about how the quality control system works in cells could help researchers one day figure out how to provide humans with a better cellular quality of life, and therefore delay degenerative diseases related to aging, such as neurodegenerative diseases.
Morimoto and Labbadia found the genetic switch occurs between two major tissues that determine the future of the species: the germline and the soma (the body tissues of the animal, such as muscle cells and neurons).
Once the germline has completed its job and produced eggs and sperm -- necessary for the next generation of animals -- it sends a signal to cell tissues to turn off protective mechanisms, starting the decline of the adult animal.
"What we discovered is exactly at this moment of reproductive maturity, all of these essential cell responses decline simultaneously," he said.
When the researchers blocked the signal between the germline to the other cells, the worm became bigger and stronger.
"We ended up creating a superworm that had been protected against all kinds of environmental insults that would kill the animal," Morimoto added.
One expert said the paper provides new insights into aging of cells.
"The study by Dr. Morimoto's lab in this paper provides a potential molecular mechanism linking the reproduction and aging," said Jose Velazquez, director of the division of aging biology at the National Institute on Aging in an e-mail to Discovery News. "The paper describes events happening in early adulthood in the worm. It seems to suggest that there is an important switch in cell stress response pathways at the time of sexual maturity. It's very interesting."
Morimoto said the next step is to look at human skin cells and see if he can find a similar cellular aging switch.