A group of researchers found that by activating genes involved in UV protection during the day, human skin stem cells protect themselves against radiation-induced DNA damage.
Human skin must cope with UV radiation from the sun and other harmful environmental factors that fluctuate on a daily basis.
Therefore, a study by Salvador Aznar Benitah, an ICREA Research Professor who developed this project at the Centre for Genomic Regulation (CRG, Barcelona), published in the journal Cell Stem Cell looked at how skin cells deal with these cyclical threats by carrying out different functions depending on the time of 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," says the study author who has recently moved his lab to the Institute for Research in Biomedicine (IRB Barcelona).
"This is important because it seems that tissues need an accurate internal clock to remain healthy."
According to Benitah, a variety of cells in our body have internal clocks that help them perform certain functions depending on the time of day, and skin cells as well as some stem cells exhibit circadian behaviours.
The scientist and his collaborators previously found that animals lacking normal circadian rhythms in skin stem cells age prematurely, suggesting that these cyclical patterns can protect against cellular damage.
This new study has now made it clearer as to how circadian rhythms affect the functions of human skin stem cells.
Benitah and his team, Luis Serrano and Ben Lehner of the Centre for Genomic Regulation, genes involved in UV protection become most active during the daytime to guard these cells while 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 says.
"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."