Shahin S, Cullinane C, Gray P J
Aeronautical and Maritime Research Laboratory, Defence Science and Technology Organisation, Melbourne 3032, Australia.
Chem Biol Interact. 2001 Dec 21;138(3):231-45. doi: 10.1016/s0009-2797(01)00275-7.
The extent and role of mitochondrial DNA damage in the mechanism of action of sulphur mustard (SM) is poorly understood. In this study, a combination of quantitative polymerase chain reaction and Southern hybridization was used to determine the levels of both total DNA adducts and DNA interstrand crosslinks in genomic and mitochondrial DNA isolated from normal human epidermal keratinocytes exposed to SM. The formation of both types of lesions occurred simultaneously in nuclear and mitochondrial DNA, however, SM produced significantly higher levels of both total adducts and crosslinks in genomic DNA than mitochondrial DNA. The total lesion frequency was 0.45 lesions/kb per 100 microM SM in the DHFR gene and 0.12 lesions/kb per 100 microM SM in the mitochondrial segment. Interstrand crosslinks occurred at a frequency of 0.28 crosslinks/10 kb per 100 microM SM in the DHFR gene and 0.05 crosslinks/10 kb per 100 microM SM in the mitochondrial segment. DNA interstrand crosslinks are thought to be the critical lesion produced by similar bi-functional alkylating agents. However, the levels of DNA cross-linking revealed in this study show that even at vesicating doses of SM mitochondrial DNA is still largely free of cross-links and the predominant form of DNA damage contributing to cell death occurs in the nucleus.
硫芥（SM）作用机制中线粒体DNA损伤的程度和作用尚不清楚。在本研究中，采用定量聚合酶链反应和Southern杂交相结合的方法，测定了从暴露于SM的正常人表皮角质形成细胞中分离出的基因组DNA和线粒体DNA中总DNA加合物和DNA链间交联的水平。两种类型的损伤在核DNA和线粒体DNA中同时发生，然而，SM在基因组DNA中产生的总加合物和交联水平显著高于线粒体DNA。在二氢叶酸还原酶（DHFR）基因中，每100 microM SM的总损伤频率为0.45个损伤/kb，在线粒体片段中为0.12个损伤/kb。在DHFR基因中，每100 microM SM的链间交联频率为0.28个交联/10 kb，在线粒体片段中为0.05个交联/10 kb。DNA链间交联被认为是由类似的双功能烷基化剂产生的关键损伤。然而，本研究中揭示的DNA交联水平表明，即使在引起水疱的SM剂量下，线粒体DNA仍然基本没有交联，导致细胞死亡的主要DNA损伤形式发生在细胞核中。
