We all know that if we spend a lot of time exposed to the sun without protection we will burn The skin becomes red, hot and inflamed and hurts with a simple touch. Then it peels off and for days we can barely touch each other. That’s clear, we don’t need science to explain it to us because practically all of us have experienced it at some point. However, we were wrong about the origin of those sunburn. We have always thought it was due to DNA damage. That’s what the textbooks say. Now, however, an international team of scientists has shown that, in reality, they are the RNA damage those that give rise to that unpleasant effect. These researchers, coming from the University of Copenhagen and Nanyang Technological Universityin Singapore, they carried out their experiments both in mice as in human skin cell cultures. This is very important, since not everything that is studied in mice can be extrapolated to humans, but cell cultures can help understand the effects on our species. With both types of experiments they observed that the response to RNA damage is much faster. At least, it is the one that seems to be closely related to sunburn. It may seem that this does not give us any interesting information. What does it matter if it’s DNA or RNA? Sunburns hurt just the same! And yes, that’s true, but this seemingly trivial fact It can help us a lot in the future. DNA or RNA? DNA is the instruction book of an organism. It contains all the information about who we are and what we need to stay alive. Our DNA contains the instructions to synthesize insulin when glucose builds up in the blood or to help us sleep through melatonin when night falls. They also include data about the color of our eyes or the way our hair grows. Everything we are is in DNA. All our cells have the same DNA, but not all DNA is used in all cells. For example, the gene with the instructions to synthesize insulin is in the cells of the eye, but it is not necessary there. It will never be used. Yes, it is necessary in the cells of the pancreas, since it is the organ that is responsible for synthesizing it. It is used there. This use of a specific gene is what is known as gene expression. The gene turns on where and when it is needed. In this case, in the cells of the pancreas (where), when glucose accumulates in the blood (when). Differences between DNA and RNA. Credit: Sponk (Wikimedia Commons) We already know what DNA is. Something more or less immutable. It can undergo mutations, but it remains more or less fixed throughout our lives. On the other side we have RNA. This is another nucleic acid. DNA is deoxyribonucleic acid and RNA is ribonucleic acid. It differs in the presence of a different sugar within the molecule: ribose In the case of RNA and deoxyribose in the case of DNA. There are many types of RNA: transfer RNA, ribosomal RNA, messenger RNA… Each one has a function, but in this case we are going to focus on the messenger, since it is the one mentioned in the study of sunburn. We have already seen that DNA is used only when and where it is necessary. This use consists of using the information contained in a gene to build a protein, which will carry out the desired function. These proteins are synthesized in cellular organelles called ribosomes. But there is a problem. Ribosomes are unable to read DNA. said very roughly speaking, It is a language they do not understand. They understand the language of messenger RNA. Therefore, when a gene is to be expressed, its information is transcribed into messenger RNA. Like when we translated a page from an instruction book that was in English into Spanish so that our grandmother knew how to use the washing machine. That is the function of messenger RNA. With this well learned, we can move on to the next thing. What does all this have to do with sunburn? Sunburn is caused by exposure to the Sun’s radiation. Specifically, ultraviolet raysespecially type B (UVB). This generates DNA damage, it is totally true. In fact, these DNA damages can accumulate and eventually lead to a melanoma. None of that has changed. However, we usually think that sunburns are that first warning that DNA has been damaged and, in reality, it turns out that it has not. It is the messenger RNA the one who gets upset. How UVB affects ZAK signaling pathways to cause sunburn symptoms. (Lind et al., Molecular Cell, 2025) After reading the literature and carrying out several experiments, the authors of the study that has just been published thought that sunburn could be related to a protein called ZAK-alpha. This is involved in the response to something known as ribotoxic stress. That is, when a failure is detected in the messenger RNA, this protein starts the immune system to attack the cells in which this damage is found, so that the altered messenger RNA not translated on the ribosome. If that happened, you would get failed proteins and could be dangerous. This immune system response also launches an inflammatory response. The skin turns red, becomes hot, swells… What does it sound like to you? Indeed, sunburn! This entire cascade of reactions to ultraviolet radiation was detected in human skin cell cultures. But what would happen in a living organism? The scientists tried to genetically modify a group of mice so that the gene with the instructions for synthesizing the ZAK-alpha protein was not present. If there was no ZAK alpha, when the mice were exposed to ultraviolet B radiation They did not experience burns. On the other hand, with ZAK-alpha intact they did. What is the use of knowing all this? The authors of the research believe that this new … Read more
