Not only people possess an inner clock, skin cells do too. According to a joint Spanish and Swiss study published in "Cell Stem Cell", skin cells perform different functions according to the time of day.
The researchers examined human skin cells and skin stem cells in cultures and living mice. They found that certain groups of genes show different activity during the course of the day. During the day mainly those producing UV protection factors are highly active.
This is controlled by the inner clock. "In this way, they (the skin cells) know when to perform what function", said study leader Salvador Aznar Benitah from the Institute for Biomedical Research in Barcelona. The cyclical activity pattern protects the cells which would age quicker without the inner clock.
In mice as well as in humans, this clock gets out of step with increasing age, said Benitah. The researchers therefore hope that their findings help produce new strategies to prevent premature ageing and cancer in humans.