The skin cells can be hairy or sweaty, and their destiny is decided by the competing interactions, with diverse signaling pathways that act at certain times during the embryonic development.
Hairy Or Sweaty, Cell Fate Is Determined During Embryonic Development
The fate of a skin cell, whether it is destined to support hair growth or secretion of sweat, is determined during the embryonic development. The researchers have spotted the exact timing during embryo formation that decides whether skin cells will be sweaty or hairy.
Distinct from other mammals that have to pant or run for shade when under the sun, humans are capable enough to cool down on their own through sweating. This is due to the uniqueness of the human skin, which is competent enough to make both hair and sweat glands generate in the same area of the body.
Investigation Made On Mice Skin
Catherine Lu and her team of researchers at the Rockefeller University investigated the unique mice skin cells varying from their hairy backs to their sweaty paws. Incidentally, mice tend to have skin cells that only favor the development of hair follicle on their back and skin cells that only favor the development of sweat glands on their paws.
The RNA expression of both these skin cell subtypes were taken and compared to spot the differences. The team discovered that mesenchymal-derived bone morphogenetic proteins (BMPs) were found to be considerably higher in the foot skin cells, in contrast to the skin cells on the back of the mice. Of all the proteins, Bmp5 was found to be responsible for distinguishing the skin cell fates.
"In samples of human scalp skin, they found increased expression of BMP and FGF genes at week 17 compared to week 15, which is coincident with the shift from hair to sweat-bud formation in humans," reported in Science Daily.
Bmp5 Levels And Sweat Glands
In the paper published in the journal Science, the researchers concluded that by altering Bmp5 levels, the skin type can be varied from being hair supportive to being sweat gland friendly. For example, by blocking Bmp5 in the foot skin of mice, the number of sweat glands generated during embryonic development can be reduced. Lu, also a coauthor of the study, discovered other mechanisms that were responsible for distinguishing the skin cell types, such as Wnt and FGF proteins.
Yung Chih Lai and Cheng-Ming Chuong with China Medical University Hospital offer a Perspective piece on the work done by the team in the same journal issue. According to them, these discoveries can be the stepping stones in the skin regeneration therapies in future.