No better way to ruin a summer day than with a sunburn. Splotchy, red, irritated skin that makes you want to curl up in a dark room. While sunscreen and shade are still the best advice for preventing a sunburn, researchers are uncovering more information about what causes them.
Previously, experts assumed that sunburns were a response to ultraviolet (UV) rays damaging an individual’s DNA. However, a joint study conducted by researchers from the University of Copenhagen and Nanyang Technological University in Singapore has revealed that the effects of a sunburn (red, irritated skin) are actually caused by damage to the RNA.
“This new knowledge turns things upside down,” said Simon Bekker-Jensen, a lead author on the study and a professor at the University of Copenhagen’s Department of Cellular and Molecular Medicine, in a statement. “I think most people associate sunburn with DNA damage; it is established knowledge. But now we need to rewrite the textbooks, and it will affect future research on the effects of UV radiation on the skin.”
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RNA, or ribonucleic acid, is a molecule that carries genetic information from the DNA to ribosomes, cellular structures that translate genetic information into proteins. These proteins inform the structure and functions of our organs and tissues.
“RNA damage happens all the time and does not cause permanent mutations. Therefore, we used to believe that the RNA is less important, as long as the DNA is intact. But in fact, damages to the RNA are the first to trigger a response to UV radiation,” said Anna Constance Vind, an assistant professor in the University of Copenhagen’s Department of Cellular and Molecular Medicine.
This isn’t to say UV radiation can’t damage DNA. But DNA damage is separate from the damage that causes sunburns. DNA damage also tends to be more serious, causing mutations in cells that are passed down to new cells, increasing the risk of issues such as skin cancer. Whereas RNA is a more transient molecule, resulting in a faster response to damage caused by UV radiation.
According to the study, sunburns are caused by a protein called Zak-alpha. It acts as a kind of surveillance system within the body’s cells. When skin was exposed to UV radiation, Zak-alpha responded to the RNA damage, recruiting immune cells that triggered cell death and the inflammation of the skin—a.k.a. a sunburn. This protects the skin from further damage.
Researchers tested the theory on mice and human skin cells. Both had the same response to UV radiation—the Zak-alpha protein triggered cell death and inflammation. But when researchers removed the Zak-alpha protein, they found that sunburn responses disappeared.
Discovering the role of RNA damage and Zak-alpha’s response to UV radiation could change the entire approach to preventing and treating sunburns, the researchers said. Not to mention other skin diseases.
“Many inflammatory skin diseases are worsened by sun exposure,” said Franklin Zhong, a co-author on the study and an assistant professor at Nanyang Technological University’s Lee Kong Chian School of Medicine. “Thus, understanding how our skin responds at the cellular level to UV damage opens the door to innovative treatments for certain chronic skin conditions.”
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