Switch that Controls Aging Identified in Worms

A biologic switch that controls lifespan in tiny worms has been identified by researchers at the University of Colorado (Boulder, USA). Their finding was reported in the December 11, 2001, issue of Current Biology.

The switch, known as DAF-16, is a protein that can either lengthen or shorten the lifespan in the eyelash-sized roundworm, C elegans. DAF-16 is a critical part of a complex signaling pathway that involves insulin and glucose. When it penetrates the nucleus, it seems to turn on a switch that lengthens the life of the roundworm. The switch is controlled by food availability, temperature, and stress. The researchers say a similar protein is likely found in humans.

Insulin released with glucose in humans rises and stores more fat when humans consume sugar, inhibiting DAF-16 to enter the nucleus. The same process is likely in animals. When DAF-16 is located in the cytoplasm of cells outside the nucleus, it is in the "off' mode. When the cell is seeking more food, DAF-16 enters the nucleus, triggering a cascade of biochemical events that lead to a longer lifespan.

According to the researchers, the longer-lived species of C elegans have a higher resistance to free radicals and environmental stress. They say there is a good possibility that a pharmaceutical could be developed that would trigger translocation of DAF-16 into the cell nucleus, causing organisms to lower their reproduction level and fight off the negative impact of free radicals.

"If DAF-16 is ‘on,' it triggers less reproduction, more efficient cell repair and longer lives,” noted Thomas Johnson, professor of psychology at the University of Colorado and a research associate. "On the other hand, if DAF-16 is ‘off,' the result is more reproduction, worse cell repair, and a shortened lifespan.





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