UV-induced cis-syn cyclobutane pyrimidine dimer (CPD) (CPD)

UV-induced cis-syn cyclobutane pyrimidine dimers (CPDs) are the most prevalent form of DNA damage caused by exposure to ultraviolet radiation, specifically in the UVB (280–315 nm) and UVC ranges (Sinha & Häder, 2002). These lesions occur when two adjacent pyrimidine bases—typically two thymines or a cytosine and a thymine—undergo a photochemical reaction to form a four-membered cyclobutane ring (Cadet et al., 2005). The presence of CPDs causes significant structural distortion of the DNA helix, which can stall DNA polymerase and RNA polymerase, leading to cell cycle arrest or apoptosis (Sancar, 1996). If these dimers are not accurately repaired by the nucleotide excision repair (NER) pathway, they can result in UV-signature mutations (C to T transitions), which are primary drivers of skin cancers such as basal cell carcinoma and melanoma (Mouret et al., 2006). Therapeutic approaches include the use of topical liposomal delivery of DNA repair enzymes, such as T4 endonuclease V, to accelerate the removal of these lesions in high-risk individuals (Yarosh et al., 2001). Additionally, sunscreens act as a primary preventive measure by absorbing or reflecting the UV radiation that triggers CPD formation (Diffey, 2002).

Other names

Cyclobutane pyrimidine dimerThymine dimerPyrimidine dimerDNA photoproductcis-syn CPDUV-induced DNA lesion

Direct enzymatic repair of DNA lesions via nucleotide excision or base excision repair pathways; prevention of formation via UV filtration.