The reason for gray hair is the Wnt signaling path

Researchers at the Langone Medical Center at New York University, working under the guidance of Associate Professor Mayumi Ito, have demonstrated that the Wnt protein-mediated signaling mechanism involved in the regulation of many biological processes can change hair pigmentation.

Experts have long known that hair color is ensured by the coordinated functioning of two types of hair follicle stem cells, from which epithelial cells and melanocytes are formed, producing melanins – pigments responsible for hair color (as well as skin and eyes). However, the mechanisms of interaction of these cells have so far been unclear.

Each follicle from the moment of its formation to death in a few years goes through repeated cycles:
anagen (hair growth phase), catagen (transitional phase), telogen (resting phase).

Using genetically modified mouse models, the researchers analyzed the role of Wnt protein-mediated signaling mechanisms in the joint work of epithelial stem cells of hair follicles and stem cells that give rise to melanocytes, which results in hair growth and pigmentation. They also demonstrated that the absence, as well as the suppression or disruption of the activity of these mechanisms in the epithelial stem cells of hair follicles prevents the regrowth of lost hair. Violation of the interaction between these cells and the precursor cells of melanocytes, also mediated by the Wnt protein, prevents the activation of the latter and, accordingly, leads to a violation of the synthesis of pigments and graying of hair, which is one of the signs of aging of the body.

Epithelial stem cells express the Wnt protein, which at the initial stages of anagen activates the corresponding signaling mechanisms both in the epithelial stem cells themselves and in the stem cells giving rise to melanocytes. Activation of the Wnt-mediated signaling mechanism triggers the differentiation of stem cells of both types. Forced activation of the Wnt-mediated signaling mechanism in epithelial cells induces the expression of the endothelin protein that stimulates the proliferation of melanocytes.

The results of the study indicate that manipulations of Wnt-mediated signaling mechanisms can theoretically be used not only to eliminate hair graying, but also to treat malignant melanoma characterized by uncontrolled growth of melanocytes. The researchers also note that the mechanism they identified is a model of regeneration of complex organs carried out through the interaction of stem cells of different types.

Article by Piul Rabbani et al. Coordinated Activation of Wnt in Epithelial and Melanocyte Stem Cells Initiates Pigmented Hair Regeneration is published on June 11 in the journal Cell.

Evgeniya Ryabtseva
Portal "Eternal youth" www.vechnayamolodost.ru Based on NYU Langone Medical Center: New Research Provides Clues on Why Hair Turns Gray. 

17.06.2011