"It is important to understand the hair cycle because the timing of the signaling required to regenerate a hair follicle is critical," Thompson said.
The scientists focused on a gene known as Hairless, which encodes a protein that is essential for hair follicle regeneration. In humans and mice with mutations in the Hairless gene, hair growth is initially normal, but once hair is shed, it does not grow back.
Potential Treatment
The new study shows that the mechanism by which Hairless regulates hair regrowth is by controlling the timing of a key signaling pathway.
Hairless "turns off" a gene that makes a protein called Wise. In cells lacking Hairless, continual accumulation of Wise appears to prevent the hair cycle from switching from the rest to the regrowth phase.
"By turning off an inhibitory protein … Hairless turns on [this] signaling in the proper cells and at the proper time in the hair cycle … inducing hair regrowth," Thompson said.
Bald mice that were genetically engineered to produce the Hairless protein were able to regrow thick fur.
Lacking Hairless is a rare genetic disorder and is not the reason why a person goes bald. But the findings could help scientists better understand the signals guiding the regrowth of hair. This, in turn, could aid the development of potential treatments for baldness.
"Each step in the [hair cycle] process is two things: a step where something could go wrong to cause baldness, but also a step which you could potentially design a treatment that might circumvent whatever went wrong to cause baldness," Thompson said.
"There are certainly parts of the puzzle that remain to be solved," she added. "But this work has given us a better understanding of the molecular mechanisms, or step-by-step process, by which hair growth is regulated."
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