Skin stem cells run on a circadian clock
From physorg.com by Bob Yirka:
Most everyone has heard of the circadian rhythm or the internal clock that people have that tells them when to do things, such as go to sleep. In fact, researchers have actually located where this “clock” resides in the human brain. It’s in the suprachiasmatic nuclei, a pair of distinct groups of cells located in the hypothalamus. So, that would seem the end of it right, except it’s not; new research by a group in Spain has found that individual stem cells in skin have their own circadian clock of sorts that tells the skin when to do certain thing, like regenerate. The team led by Peggy Janich and Salvador Aznar Benitah, has published the results of their study in Nature.
Janich, Benitah, et al, knew that mice grew new skin cells mostly at night, but weren’t sure how exactly that came about. To find out they studied a protein produced in the skin called Per1, which they suspected had clock-like abilities and that it impacted the expression of signaling proteins which tell other cells when to start doing their thing – such as growing new cells. To see what it was doing they linked the Per1 cell with another protein that goes fluorescent when exposed to certain environmental factors. This allowed them to see when the Per1 cells were active or dormant. In watching the cells they found they oscillated over regular 24 time period. They also found that the amount of brightness shown by the fluorescent protein correlated directly with the amount of signaling protein expressed.