Some people sport a beautiful head of gray hair, while others dye or pluck it out. Gray hair isn't just a matter of aesthetics. Recent research on stem cells shows that a hair can lose its color—and thus turn white or gray—to prevent cancer from developing. These results, published in the journal Nature Cell Biology, might well change our perspective on those silvery filaments that slip into our hair.
Throughout our lives, our cells are exposed to factors that can damage DNA. Damaged DNA can lead to cell aging or the development of cancer. All cells are affected, including the specialized stem cells in our hair follicles. Called McSCs, these cells produce melanocytes, the cells that color our hair and skin. With each hair growth cycle, they ensure the regeneration of the pigments that give us our color.
Sacrificing oneself rather than becoming a tumor
Sometimes, the damage to DNA proves to be very severe, particularly breaks double-strand " : this means that the two strands that form " the ribbon "Some of the DNA is damaged." Normally, cells can repair a certain amount of DNA. But when cells experience DNA damage exceeding a certain threshold, the damage is beyond what they can repair." explains Dr. Yasuaki Mohri, from the University of Tokyo, who authored this work.
When faced with this challenge, McSCs don't hesitate. They trigger a mechanism called senodifferentiation. In practical terms, they differentiate irreversibly, thus ceasing to be stem cells and eventually disappearing. Without stem cells, there are no more melanocytes, and without melanocytes, there is no more color. The hair then becomes gray or white. It's important to understand that gray hair itself doesn't protect against cancer. Rather, it results from a mechanism that eliminates severely damaged and potentially dangerous cells.", the researcher continued.
Sometimes, the McSCs don't " sacrifice "Not because of a molecule produced by the epidermis. This molecule, KIT ligand, prevents senodifferentiation. The cells then continue to renew themselves despite the DNA damage and are pushed towards a pathway that promotes tumors."
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“ We believe that this reaction is universally present in many of our tissues“
Alongside this newly discovered mechanism, there are many reasons why our hair turns gray or white, including genetic factors and more. stressResearchers would now like to know if this reaction observed in scalp stem cells is also found elsewhere in the body. We believe that this reaction is universally present in many of our tissues“, supposes Yasuaki Mohri. A " sacrifice "that our cells would accomplish in silence, without us even realizing it."
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