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Researchers at Rockefeller University have identified two proteins that enable skin stem cells to regenerate themselves to produce either skin or hair. The study, published in Nature Genetics, identifies Tcf3 and Tcf4 as the proteins responsible for regenerating the epidermis or stimulating hair follicles. This finding, according to the researchers, could possibly be used in regenerative therapies for burned skin or hair loss.
Tcf3 and Tcf4 reside in the nucleus of skin stem cells, where they bind to DNA to turn genes off that would otherwise cause the stem cells to differentiate. The researchers found that without these proteins, the epidermis cannot be maintained for a long period of time.
The study was lead by Elaine Fuchs, head of the laboratory of mammalian cell biology and development, and first author Hoang Nguyen, an assistant professor at Baylor College of Medicine. The two used mice engineered to lack Tcf3 and Tcf4. They reported that without Tcf3 and Tcf4, all of the layers of the mice’s skin still develop properly, but they cannot be maintained.
The researchers also reported an interesting finding concerning β-catenin. Tcf proteins turn genes on with the help of signals they receive from their molecular environment that result in the stabilization of partner molecule β-catenin. Tcf3 and Tcf4 maintain stem cells as stem cells without β-catenin; however, with β-catenin, hair growth is activated. Alternatively, Tcf3 and Tcf4 maintain the epidermal stem cells without β-catenin.