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A recent study examines why some parts of the human body remain hairless while others become hirsute. The results may offer clues to baldness in both men and women.
Humans have hair in some places but not in others. The top of our heads is usually filled with hair, while the soles of our feet are not.
This is certainly not news, but the reason we have hair on our legs and arms, but not on the palms of our hands, remains a headache.
Hair loss
affects a considerable part of society, especially men, and can cause considerable distress to some people.
Baldness in men and women, which are common hereditary forms of hair loss, affects about 80 million people in the United States.
Because of the prevalence of hair loss and its potential psychological impact, the mechanisms that regulate hair growth are of great interest.
The mystery of hair distribution
Although we now understand how hair grows, the reason they grow in some places but not to others remains to be debated.
A team of researchers from the Perelman School of Medicine at the University of Pennsylvania in Philadelphia recently adopted a new approach. The newspaper Cell reports published its findings today.
In particular, researchers focused on TNO pathways. These signaling pathways play an essential role during embryonic development and continue to play a role in the regeneration of certain body tissues in adulthood.
The lead co-author, Professor Sarah E. Millar, explains why they focused on this path:
"We know that WNT signaling is crucial for the development of hair follicles, blocking it causes the formation of hairless skin and its activation causes the formation of more hair."
The team was also interested in a protein called Dickkopf 2 (DKK2), which belongs to a family of natural inhibitors that play an important role in embryonic development. DKK2 is known to inhibit WNT pathways.
To investigate the potential role of the WNT and DKK2 pathways in hair distribution, the team studied the plantar skin in mice, analogous to the underside of the human wrist.
In the plantar skin of mice, there were high levels of DKK2 expression. The researchers also found that if they removed the genes responsible for producing DKK2, the hair grew on the skin sample.
Professor Millar explains that "
Mice compared to rabbits
In another experiment, the team decided to examine the plantar skin of the rabbit, because the hairs grow there. As expected, DKK2 levels in rabbit plantar tissue were much lower than those of mouse tissue.
Due to the lower levels of DKK2, there is no inhibition of WNT, which allows the hair to grow. The team plans to continue studying this mechanism in other scenarios.
"In this study, we showed that skin in hairless regions naturally produced an inhibitor that prevented the WNT from doing its job."
-Teacher. Sarah E. Millar
As we develop in the uterus, our hair follicles develop. However, once we are born, we do not produce them anymore. We have about 5 million hair follicles at birth and they have to last a lifetime.
This explains why the skin remains glabrous after a burn or injury. The team wants to understand if the removal of WNT channels also plays a role.
Previous research has revealed an association between the DKK2 gene and baldness in men and women. Understanding more about the molecular basis of this relationship could help shape treatments for hair loss in the future.
Professor Millar notes that this is definitely not the end of the line.
"We hope that these lines of investigation will unveil new ways to improve wound healing and hair growth, and we plan to pursue these goals to move forward," he said. she said.
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