Why We Sunburn

Until recently, the exact molecular basis for why a sunburn occurs was not well known. We know that continual unprotected exposure to UVB  increases your chances of getting sunburn and developing skin cancer. Sunburn is an inflammatory response to something that UVB radiation effects at the molecular level of in our skin cells.

This year researchers at UC San Diego have observed that sunburning of the skin is a response to damage in non-coding RNA domains. RNA is normally a single stranded nucleic acid molecule. It’s function is basically “in the transportation of information from our DNA to the ribosomes, and the interpretation of the information provided from our DNA.

Researchers have found that UVB radiation causes structural changes in what is known as “small nuclear RNAs.” These RNAs are non-coding (it’s function doesn’t code for protein synthesis).

A visual of secondary RNA structure

The “RNA-RNA crosslinking, pyrimidne dimer formation, and guanine oxidation” induced by UVB radiation is in turn detected by a pattern-recognition molecule that specifically recognizes dsRNA molecules, called TLR3. Activation of this protein, induces cytokine (cytokines are small signalling molecules) production of specifically TNF-alpha and IL-6. TNF-alpha is “known to induce a pro-inflammatory response, apoptosis, and immunosuppression.” Bottom line is, UVB radiation cause somewhat of a domino effect on the molecular level. Something gets damaged and our body has to heal itself somehow so it activates an inflammatory response. 

For me personally, as someone who works in genomics with a passion for cosmetic science, I think  it’s great to see these two disciplines cross paths in terms of finding solutions to skin concerns.