The answer they found scientists from the US. Ultraviolet B radiation (UVB) sun damage the RNA molecules of skin cells, report in the journal «Nature Medicine».
The RNA, or ribonucleic acid is part of the cell's genetic material, encoding information that convert the genetic instructions in DNA into proteins.
When the RNA is damaged by UVB, ceases to encode proteins, They say scientists from the Medical School of the University of California, in San Diego.
When this happens, adjacent burnt cells release inflammatory molecules, triggering a chain of chemical reactions which lead to the symptoms of sunburn.
medium-, these chemical reactions leading to skin healing from the burn.
Long term, Nevertheless, the same reactions add up and increase the risk of skin cancer.
"This inflammatory response is essential for the process of the skin wound after the death of skin cells', said lead researcher Dr. Richard L.. Galo, Professor of Medicine and Director of the Department of Dermatology of the University.
Although scientists knew for years many of the molecular effects of overexposure to the sun, until now they did not know exactly how the skin lesions begin - and this gap fills new research.
The researchers hope that now discovered the first step of sunburn, They will be able to find ways to curb - at least for light-sensitive people, if not for all of us.
In the category of light-sensitive people, example, are people with psoriasis, being treated (and) UV, but a potential side effect of this treatment is to increase the risk of skin cancer.
"Our discovery suggests a way to enable people with psoriasis benefit from treatment with UV, without actually being exposed to the harmful UV », said Dr. Galo.
"Some people, Moreover, such as those suffering from lupus, They are extremely sensitive to UV and should avoid the sun. We are looking for ways to help them and, blocking the chemical mechanism we discovered ".
The researchers discovered the mechanism in the laboratory by exposing human skin cells to UVB and then doing experiments in mice.
Specific genes in mice can determine how likely it is to suffer skin burns from the sun, explained Dr. Gallo.
"People have similar genes, but it is not known if they have mutations of genes that may affect the reaction of the skin to the sun ', added.
Source:ygeia.tanea