Skin under a microscope, before or after ultraviolet exposure (simulating sunlight). Normal skin (p53+/+) becomes tanned as indicated by the dark arcs of melanin pigment within skin cells, p53 deficient skin (p53-/-) fails to become pigmented after identical UV exposure. Credit: Rutao Cui, Dana-Farber Cancer Institute.
A study published in the journal Cell this week may explain why spring can’t come soon enough. Researchers identified a gene essential to our skin’s tanning process—and why sunny days make us happy. P53, the implicated gene, was discovered in 1979 and is most famous for suppressing tumors. P53 kicks into gear when a cell’s DNA is damaged—if a mutation causes a cell to grow out of control, in the case of a tumor, for example, p53 instructs that cell to commit suicide.
Perhaps it shouldn’t be surprising that the gene should play a role in tanning too, says David E. Fisher, the Director of the Melanoma Program and the Dana-Farber Cancer Institute and a professor of pediatric hematology and oncology at Harvard Medical School. “With the discovery, there was kind of this moment of ‘ah-ha, that makes so much sense,’” says Fisher. Given p53’s role in damage control, it reasons that the gene is pertinent to how we cope with the sun—a common form of DNA damage.
When the UV rays hit our skin, p53 begins a chain reaction, beginning with the activation of a gene called pro-opiomelanocortin (POMC). POMC then cleaves out segments of itself and one of these pieces is a hormone that prompts skin cells to secrete melanin. The melanin protects us from the UV rays, and gives us a bronzing tan.
During the p53 induced cleavage, POMC also releases a hormone called beta-endorphin, one of the body’s natural opiates. (Heroin, methadone and morphine also belong to the opiate family.) Although the role of beta-endorphin in the body is not entirely clear, Fisher says it’s possible that people could become addicted to the endemic opiate.
LISTENING STATION: SOUND BITES
DAVID FISHER
DIRECTOR OF THE MELANOMA PROGRAM
DANA-FARBER CANCER INST
PEDIATRIC HEMATOLOGY & ONCOLOGY
HARVARD MEDICAL SCHOOL
The sun, therefore, can have a literally intoxicating effect by prompting release of beta-endorphin through the same process that ultimately produces melanin. As such, this study may provide new insight into why Californians seem happier (because they really are), why people like tanning salons and why the beach beckons.
-Flora Lichtman
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