Reduction of 8-oxodGTP in the nucleotide pool by hMTH1 leads to reduction in mutations in the human lymphoblastoid cell line TK6 exposed to UVA
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- 作者：Asal ; Fotouhi ; Sara ; Skiö ; ld ; Sara ; Shakeri-Manesh ; Siv ; Osterman-Golkar ; Andrzej ; Wojcik ; Dag ; Jenssen ; Mats ; Harms-Ringdahl ; Siamak ; Haghdoost ; ; ; siamak.haghdoost@gmt.su.se
- 关键词：Oxidative stress ; hMTH1 ; Mutagenesis ; UVA ; 8-oxo-dG ; 8-OH-dG ; 8-oxo-dGTP ; Reactive oxygen species
- 刊名：Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis
- 出版年：2011
- 出版时间：1 October 2011
- 年：2011
- 卷：715
- 期：1-2
- 页码：13-18
- 全文大小：320 K
文摘
UVA has been suggested to play an important role in UV-induced mutagenesis. The mechanisms by which UVA induces mutations are still a matter of debate. Our aim was to investigate the protective capacity of hMTH1, a nucleotide pool sanitization enzyme with 8-oxodGTPase activity. Human B lymphoblastoid cells were stably transfected with shRNA directed against hMTH1. Clonogenic survival, mutations, intracellular and extracellular levels of 8-oxodG (8-oxo-7, 8-dihydro-2?deoxyguanosine) and dG in the nucleotide pool of UVA-irradiated transfected and non-transfected cells were investigated. Mutations were determined in the thymidine kinase locus. Intracellular 8-oxodG and dG were measured using a modified ELISA and HPLC, respectively, after extraction of the nucleotide pool and conversion of nucleotides to their corresponding nucleosides. 8-oxodG in the medium was measured using ELISA. UVA-induced mutations were significantly higher while the survival was slightly lower in transfected compared to non-transfected cells. The increased mutation rate in transfected cells at increased exposure correlated with enhanced levels of 8-oxodG in the nucleotide pool, and a somewhat reduced level of 8-oxodG in the medium. The results indicate that the nucleotide pool is a significant target for UVA-induced mutations and implicates that hMTH1 plays an important role in protecting cells from UVA-induced oxidative stress.