The Mechanisms of UV Mutagenesis

Abstract

Ultraviolet (UV) light induces specific mutations in the cellular and skin genome such as UV-signature and triplet mutations, the mechanism of which has been thought to involve translesion DNA synthesis (TLS) over UV-induced DNA base damage. Two models have been proposed: "error-free" bypass of deaminated cytosine-containing cyclobutane pyrimidine dimers (CPDs) by DNA polymerase η, and error-prone bypass of CPDs and other UV-induced photolesions by combinations of TLS and replicative DNA polymerases--the latter model has also been known as the two-step model, in which the cooperation of two (or more) DNA polymerases as misinserters and (mis)extenders is assumed. Daylight UV induces a characteristic UV-specific mutation, a UV-signature mutation occurring preferentially at methyl-CpG sites, which is also observed frequently after exposure to either UVB or UVA, but not to UVC. The wavelengths relevant to the mutation are so consistent with the composition of daylight UV that the mutation is called solar-UV signature, highlighting the importance of this type of mutation for creatures with the cytosine-methylated genome that are exposed to the sun in the natural environment. UVA has also been suggested to induce oxidative types of mutation, which would be caused by oxidative DNA damage produced through the oxidative stress after the irradiation. Indeed, UVA produces oxidative DNA damage not only in cells but also in skin, which, however, does not seem sufficient to induce mutations in the normal skin genome. In contrast, it has been demonstrated that UVA exclusively induces the solar-UV signature mutations in vivo through CPD formation.

Generation and characterization of pigment mutants of Chlamydomonas reinhardtii CC-124

“…At 5-min exposure, significantly no algal growth was observed. It is clear that UV light has a lethal effect on the cells' viability and created opportunities for optimal formation of morphological mutations due to its ability to induce highly efficient DNA damage with a survival curve of C-shape (Figures 1 and 2)/ This is in agreement with the reports of many researchers on the effect of UV light on algal microorganisms (Cadet et al, 1992;Danilchenko et al, 2002;Wu et al, 2005;Deng et al, 2011;IKehata and Ono, 2011). In exposing C. reinhardtii CC-124 to UV radiation with 5 W/m 2 for 1 to 5 min, out of 130 000 cells of C. reinhardtii strain, 14086 morphological surviving sub clones were formed.…”

Correlation between cell cycle proteins and hMSH2 in actinic cheilitis and lip cancer

“…Both lesions have similar characteristics with skin lesions and also share the same main etiological agent, ultraviolet (UV) radiation, particularly the UVB [33]. The carcinogenesis process induced by UV, is still not fully elucidated, but it is known that exposure to endogenous and exogenous genotoxic agents, such as UV, can lead to oncogenic mutations resulting from perturbation of the cell cycle and damage to DNA repair systems [15,30,31].…”

3D Printed Scaffolds as a New Perspective for Bone Tissue Regeneration: Literature Review

“…However, most photo initiators are insoluble in water and need to be dissolved in organic solvents, which makes them toxic for cells. That is added to the risk of breaking the DNA's double helix with UV radiation [180]. For that, the printing of cells along with the scaffold is not recommended, and so the cells are sedimented in the scaffold after its manufacturing [61].…”