Cyclobutane pyrimidine dimers and (6-4) photoproducts (CPDs and 6-4PPs)

Cyclobutane pyrimidine dimers (CPDs) and (6-4) photoproducts (6-4PPs) are the primary DNA lesions formed when skin is exposed to ultraviolet (UV) radiation, particularly UVB (Sinha & Häder, 2002, Photochemical & Photobiological Sciences). These lesions involve the formation of covalent bonds between adjacent pyrimidine bases (cytosine or thymine) on a DNA strand, which distorts the double helix structure and interferes with transcription and replication (Pfeifer et al., 2005, Mutation Research). If left unrepaired by the body's endogenous nucleotide excision repair (NER) pathway, these photoproducts can lead to characteristic UV-signature mutations, which are major drivers of skin cancers such as melanoma and basal cell carcinoma (Rastogi et al., 2010, Journal of Nucleic Acids). In therapeutic contexts, these lesions are targeted by exogenous enzymes like T4 endonuclease V or photolyases delivered via liposomes to accelerate repair and prevent oncogenesis (Yarosh et al., 2001, The Lancet). Monitoring the clearance of these lesions serves as a critical biomarker for assessing UV damage and the efficacy of photoprotective or DNA-repair-enhancing treatments (Stege et al., 2000, PNAS).

Other names

UV-induced DNA lesionsPyrimidine dimersThymine dimers6-4 pyrimidine-pyrimidone photoproductsUV-damaged DNA

Enhancement of DNA repair through exogenous delivery of repair enzymes that catalyze the excision or direct reversal of pyrimidine dimers.