The study reveals how hair pigment stem cells respond to DNA damage by making fate decisions that can result in either hair graying or the development of melanoma.
Throughout life, our cells face continual challenges from both external and internal influences that can harm their DNA. This type of damage is known to play a role in aging and the development of cancer. However, scientists have long struggled to fully understand how damaged stem cells influence the long-term health and stability of tissues.
Melanocyte stem cells (McSCs) are a special type of stem cell that generates melanocytes, the pigment-producing cells responsible for hair and skin color. In mammals, these stem cells are located in the bulge–sub-bulge region of hair follicles, where they exist as immature melanoblasts. Through repeated regeneration cycles, McSCs help maintain normal pigmentation۔
In a study published Professor Emi Nishimura and Assistant Professor Yasuaki Mohri from The University of Tokyo explored how McSCs react to different forms of DNA damage.
Using long-term in vivo lineage tracing and gene expression profiling in mice, the researchers discovered a distinct response to DNA double-strand breaks: senescence-coupled differentiation (seno-differentiation). During this process, McSCs permanently transform into mature cells and are eventually lost, leading to hair graying. This protective mechanism is controlled by activation of the p53–p21 pathway.
