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Researchers at the National Institutes of Health and the University of Alabama, Birmingham have discovered a connection between the genes that contribute to hair color and the genes that notify human bodies of a pathogenic infection. When a body is under attack from a virus or bacteria, the innate immune system reacts.
All cells have the ability to detect foreign invaders and they respond by producing signaling molecules- interferon. Interferons signal to other cells to take action by turning on the expression of genes that inhibit viral replication, activate immune effector cells, and increase host defenses.
The connection between hair pigmentation and innate immune regulation was initially a bit surprising. Genomic tools show how the genes within human genome change their expression under different conditions. Gray hair is a read-out of melanocyte stem cell dysfunction, melanocyte stem cells are essential to hair color as they produce the melanocytes that are responsible for making and depositing pigment into the hair shaft.
An unexpected link was found between gray hair, the transcription factor MITF, and innate immunity. MITF regulates many functions within melanocytes and keep the melanocytes’ interferon response in check. If MITF’s control of the interferon response is lost in melanocyte stem cells, hair-graying results.
If innate immune signaling is artificially activated in mice that are predisposed for getting gray hair, increased numbers of gray hairs are also produced. This shows that genes that control pigment in hair and skin work to control the innate immune system,” said William Pavan, study co-author and chief of the Genetic Disease Research Branch at NIH’s National Human Genome Research Institute (NHGRI).
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