Shikazono Naoya, Noguchi Miho, Fujii Kentaro, Urushibara Ayumi, Yokoya Akinari
Japan Atomic Energy Agency, Advanced Research Science Center, 2-4 Shirakata-Shirane, Tokai-mura, Ibaraki 319-1195, Japan.
J Radiat Res. 2009 Jan;50(1):27-36. doi: 10.1269/jrr.08086.
After living cells are exposed to ionizing radiation, a variety of chemical modifications of DNA are induced either directly by ionization of DNA or indirectly through interactions with water-derived radicals. The DNA lesions include single strand breaks (SSB), base lesions, sugar damage, and apurinic/apyrimidinic sites (AP sites). Clustered DNA damage, which is defined as two or more of such lesions within one to two helical turns of DNA induced by a single radiation track, is considered to be a unique feature of ionizing radiation. A double strand break (DSB) is a type of clustered DNA damage, in which single strand breaks are formed on opposite strands in close proximity. Formation and repair of DSBs have been studied in great detail over the years as they have been linked to important biological endpoints, such as cell death, loss of genetic material, chromosome aberration. Although non-DSB clustered DNA damage has received less attention, there is growing evidence of its biological significance. This review focuses on the current understanding of (1) the yield of non-DSB clustered damage induced by ionizing radiation (2) the processing, and (3) biological consequences of non-DSB clustered DNA damage.
活细胞暴露于电离辐射后，DNA会发生多种化学修饰，这些修饰要么是由DNA的电离直接诱导的，要么是通过与水衍生的自由基相互作用间接诱导的。DNA损伤包括单链断裂（SSB）、碱基损伤、糖损伤和脱嘌呤/脱嘧啶位点（AP位点）。簇状DNA损伤被定义为单个辐射径迹在DNA的一到两个螺旋圈内诱导产生的两个或更多此类损伤，它被认为是电离辐射的一个独特特征。双链断裂（DSB）是一种簇状DNA损伤，其中单链断裂在紧密相邻的相反链上形成。多年来，由于双链断裂与重要的生物学终点相关，如细胞死亡、遗传物质丢失、染色体畸变，因此对其形成和修复进行了详细研究。尽管非双链断裂的簇状DNA损伤受到的关注较少，但越来越多的证据表明其具有生物学意义。本综述重点关注目前对（1）电离辐射诱导的非双链断裂簇状损伤的产率、（2）处理过程以及（3）非双链断裂簇状DNA损伤的生物学后果的理解。
