In Sight: A Direct Connection to Melanocytes
By: Katie Schaefer, Cosmetics & Toiletries
Posted: December 28, 2006, from the January 2007 issue of Cosmetics & Toiletries.
An academic study of the pathway of UV-induced pigmentation may have created a safe tan for sunseekers. Scientists at the Dana-Farber Cancer Institute, Harvard Medical School, have begun research and evaluation of the compound forskolin, which they believe darkens skin pigmentation successfully without the use of self-tanners and without sun exposure. David Fisher, MD, PhD, director of the melanoma program in the department of medical oncology at Dana-Farber Cancer Institute, Harvard Medical School, led the research in Boston to discover what he hopes to be a safe alternative to UV exposure.
The Discovery
The major scientific breakthrough according to Fisher was that the target of UV rays was not found to be melanocytes but rather keratinocytes, which are superficial cells that lie next to the melanocytes.
“After you go out in the sun, UV exposure triggers keratinocytes to synthesize and secrete melanocyte stimulating hormone (MSH). The MSH then activates a receptor protein on the surface of adjacent melanocytes, which in turn activates an enzyme within melanocytes to trigger the melanin synthesis cascade,” said Fisher. People with red hair usually have a variant form of the receptor protein on the melanocyte surface, and their variant form often is unable to respond to MSH, which explains why red-headed individuals rarely tan.
The researchers discovered that they could bypass the variant receptor with a drug that penetrated melanocytes and directly activated the key enzyme, thereby creating pigmentation in red-haired mice.
The way the researchers chose to target the enzymes in the melanocytes was through the topical compound forskolin, a derivative of the plant Coleus forskoleii. Although the researchers chose to use forskolin, according to Fisher, there may be other compounds capable of targeting the enzyme.