That our body has ‘clocks’ is known. The best known is the circadian ‘day-night’ clock that regulates our sleep patterns and allows to anticipate environmental changes between day and night. Scientists have now found that skin cells also have an internal ‘clock’.
Skin as a Protective Barrier
Because the skin is the outermost layer of the body, it is most affected by environmental variations in conditions such as temperature, UV and sunlight. In fact, one of its main functions is to protect the body by forming a barrier to harsh environmental conditions. Wouldn’t it thus make sense for the skin to ‘sense’ changes in the environment and respond accordingly?
Some Skin Genes are Time-Dependent
Researchers in Hamburg measured the expressions of various genes in skin cells at different times of the day, and found a whole bunch of genes that were expressed differently depending on the time of the day. This means that the skin adapts to the current environment and regulates itself on the current need. Just as our clothes very with the weather, the suite of proteins and fats expressed by the skin vary according to the time of day.
They also found that many of these daytime-regulated genes were regulated by one other gene. This gene is a transcription factor, which means it doesn’t directly produce a protein, but regulates the expression of other proteins, either by inhibiting them or activating them. That is, the gene called Klf9 is a parent regulator—it is affected by the environment, and in turn, it affects the expression of other genes. However, we don’t yet know how these changes lead to differences in the activity of the skin at different times and that remains to be studied.
The job of the biological clock is to control the exact timing of various processes like cell division and DNA repair in skin. Prof. Achim Kramer, who headed this research, is already looking to the future: “If we understand these processes better, we could target the use of medication to the time of day in which they work best and have the fewest side effects.”