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Skin Clock
06 October 2012

Skin Clock

Ask the time of someone not wearing a watch and they may look at their wrist and say, “it’s freckle past hair.” What they may not know, however, is that skin really can tell time. Scientists have taken a closer look at human skin cells (pictured) and discovered that levels of certain proteins in skin depend on the time of day. For example, one protein called KLF9 (stained green), which strongly represses cell division [when one cell copies its DNA to become two cells], was found to be at its most abundant around midday. By preventing skin cell division when the sun is at its most powerful, it’s possible that KLF9 is helping protect the skin against UV-induced DNA damage. Whatever the reason for daily fluctuations in KLF9 and other skin proteins, they help the clock in the skin keep time with a central regulating clock in the brain.

Written by Ruth Williams

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BPoD stands for Biomedical Picture of the Day. Managed by the MRC Laboratory of Medical Sciences until Jul 2023, it is now run independently by a dedicated team of scientists and writers. The website aims to engage everyone, young and old, in the wonders of biology, and its influence on medicine. The ever-growing archive of more than 4000 research images documents over a decade of progress. Explore the collection and see what you discover. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.

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