Internal Clock of the Skin Protects It from UV Rays

The clock inside your skin is ticking! Yes, scientists have found that human skin stem cells possess an internal clock which helps them switch on genes involved in UV protection during the day.

"Our study shows that human skin stem cells possess an internal clock that allows them to very accurately know the time of day and helps them know when it is best to perform the correct function," said study author, Salvador Aznar Benitah, Catalan Institution for Research and Advanced Studies (ICREA) Research Professor.

"This is important because it seems that tissues need an accurate internal clock to remain healthy," Benitah said. New strategies to prevent premature ageing and cancer in humans can be formulated based on these findings.

A lot of cells in our body perform certain functions depending on the time of the day and their internal clocks help the do so. Some skin and stem cells exhibit circadian behaviours (relating to biological processes that occur regularly at about 24-hour intervals).

As yet, it had been unclear as to how circadian rhythms affect the functions of human skin stem cells.  The researchers during this study found that distinct sets of genes in human skin stem cells show peak activity at different times of day.

Genes involved in UV protection become most active during the daytime to guard these cells while they proliferate – that is, when they duplicate their DNA and are more susceptible to radiation-induced damage.

"We know that the clock is gradually disrupted in aged mice and humans, and we know that preventing stem cells from accurately knowing the time of the day reduces their regenerative capacity," Benitah said.

"Our current efforts lie in trying to identify the causes underlying the disruption of the clock of human skin stem cells and hopefully find means to prevent or delay it," Benitah said.

The study was published by Cell Press in the journal Cell Stem Cell.

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