title: Action spectrum analysis of UVR genotoxicity for skin: the border wavelengths between UVA and UVB can bring serious mutation loads to skin.
abstract: UVR causes erythema, which has been used as a standardized index to evaluate the risk of UVR for human skin. However, the genotoxic significance of erythema has not been elucidated clearly. Here, we characterized the wavelength dependence of the genotoxic and erythematic effects of UVR for the skin by analyzing the induction kinetics of mutation and inflammation in mouse skin using lacZ-transgenic mice and monochromatic UVR sources. We determined their action spectra and found a close correlation between erythema and an epidermis-specific antigenotoxic response, mutation induction suppression (MIS), which suppressed the mutant frequencies (MFs) to a constant plateau level only 2-3-fold higher than the background MF at the cost of apoptotic cell death, suggesting that erythema may represent the threshold beyond which the antigenotoxic but tissue-destructive MIS response commences. However, we unexpectedly found that MIS attenuates remarkably at the border wavelengths between UVA and UVB around 315 nm, elevating the MF plateaus up to levels ∼40-fold higher than the background level. Thus, these border wavelengths can bring heavier mutation loads to the skin than the otherwise more mutagenic and erythematic shorter wavelengths, suggesting that erythema-based UVR risk evaluation should be reconsidered.
authors: Department of Cell Biology, Graduate School of Medicine, Tohoku University, Sendai, Japan. ikehata@med.tohoku.ac.jp
authors: Hironobu
authors: H
authors: Ikehata
authors: Shoichi
authors: S
authors: Higashi
authors: Shingo
authors: S
authors: Nakamura
authors: Yasukazu
authors: Y
authors: Daigaku
authors: Yoshiya
authors: Y
authors: Furusawa
authors: Yasuhiro
authors: Y
authors: Kamei
authors: Masakatsu
authors: M
authors: Watanabe
authors: Kazuo
authors: K
authors: Yamamoto
authors: Kotaro
authors: K
authors: Hieda
authors: Nobuo
authors: N
authors: Munakata
authors: Tetsuya
authors: T
authors: Ono
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D004249:DNA Damage / Q000235:genetics / Q000528:radiation effects; D004195:Disease Models, Animal; D004307:Dose-Response Relationship, Radiation; D004890:Erythema / Q000453:epidemiology / Q000209:etiology* / Q000235:genetics*; D007763:Lac Operon / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation / Q000235:genetics*; D012307:Risk Factors; D012867:Skin / Q000473:pathology / Q000528:radiation effects*; D013057:Spectrum Analysis; D014466:Ultraviolet Rays / Q000009:adverse effects*