As with C. elegans, when rats and mice are fed low calorie diets they live longer than normal, and the first response they have on the molecular level is a drop in insulin levels. The equivalent of the daf-2 gene in humans produces the cell receptor for insulin and insulin-like growth factor (IGF), which plays a role in regulating food metabolism. And, just as in C. elegans, the human insulin receptor acts in signaling cells, amongst other places, prompting second signals that then effect the behavior of other cells.

"It may be that the signaling cascade prompted by daf-2 in certain cells occurs in a similar way in the insulin/IGF family of receptors in mammals in response to caloric restriction," said Kenyon.

If this is the case, she said, it may be that the hormone signaling pathway in C. elegans hints at a similar process regulating aging in humans. "It may be that one portion of this pathway is involved in the control of aging, so the challenge is to figure out which portion that is."

The UCSF research was funded by a grant from the National Institute of Aging.

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Contact: Jennifer O'Brien
jobrien@itsa.ucsf.edu
415-476-1407
University of California - San Francisco
15-Oct-1998