A group of researchers at NYU Langone Medical Center have found for the first time, that Wnt signaling between hair follicles and melanocyte stem cells can dictate hair color and regeneration.
The Wnt signaling pathway, which is made up of a network of proteins, has been implicated in the control over various types of stem cells and may act as a niche factor to maintain stem cells in a self-renewing state.
The new study into Wnt signaling, already known to control many biological processes was published in the June 11, 2011 issue of the journal Cell, and uncovered the latest information on hair pigmentation.
"We have known for decades that hair follicle stem cells and pigment-producing melanocycte cells collaborate to produce colored hair, but the underlying reasons were unknown," said Mayumi Ito, assistant Professor in the Ronald O. Pereleman Department of Dermatology at NYU Langone, who lead the research.
"We discovered Wnt signaling is essential for coordinated actions of these two stem cell lineages and critical for hair pigmentation."
The study suggests the manipulation of Wnt signaling may be a novel strategy for targeting pigmentation such as graying hair. The research study also illustrates a model for tissue regeneration.
"The human body has many types of stem cells that have the potential to regenerate other organs," explained Dr. Ito.
"The methods behind communication between stem cells of hair and color during hair replacement may give us important clues to regenerate complex organs containing many different types of cells."
Using genetic mouse models, researchers examined how Wnt signaling pathways enabled both hair follicle stem cells and melanocyte stem cells to work together to generate hair growth and produce hair color.
Inhibiting regeneration and coloring
The study also showed the depletion or abnormal Wnt signaling in hair follicle stem cells not only inhibits hair re-growth but also prevents melanocytes stem cell activation required for producing hair color.
Based on this, the study concluded that the lack of Wnt activation in melanocyte stem cells leads to depigmented or gray hair.
The study suggests the possibility that Wnt signaling is a key pathway for the regulation of melanocyte stem cells and shows how melanocyte behavior is associated with hair regeneration.
According to the researchers, this insight provides further understanding of diseases in which melanocytes are either appropriately lost, such as hair graying, or undergo uncontrolled cell growth, as in melanoma.