Effect of Nitric Oxide on γ-Ray-Induced Micronucleus Frequency in RAW264.7 Cells
Effect of Nitric Oxide on γ-Ray-Induced Micronucleus Frequency in RAW264.7 Cells
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DOI：
10.1667/rr3471.1
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发表时间：
2005-12
影响因子：
7.4
通讯作者：
Sachiko Tokuzumi;Mayumi Hori;M. Monobe;Y. Hosoi;S. Kojima
中科院分区：
文献类型：
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作者：
Sachiko Tokuzumi;Mayumi Hori;M. Monobe;Y. Hosoi;S. Kojima
摘要Tokuzumi，S.，Hori，M.，Monobe，M.，细野，Y.和Kojima，S.一氧化氮对γ射线诱导RAW264.7细胞微核率的影响Radiat. Res. 164，723-732（2005）中所述。研究了低剂量一氧化氮（NO）对γ射线诱发的RAW264.7细胞微核率的影响。用0.25 mM硝普钠（SNP）（一种化学NO供体）处理RAW264.7细胞，在处理后3 ~ 12 h，使5戈伊γ射线诱导的微核率降低43 ~ 45%。这种作用被羧基PTIO阻断，表明NO可能在辐射诱导的MN频率降低中起作用。为了研究这种效应的可能机制，我们首先研究了SNP治疗后抗氧化系统的变化。在SNP处理的细胞中，在处理后3和12小时之间观察到细胞内谷胱甘肽（GSH）的显著增加。用丁硫酰亚胺（BSO）耗竭GSH可增加γ射线引起的MN频率的增加。用细胞内GSH的各种诱导剂进行的详细研究表明，GSH诱导在NO降低γ射线诱导的MN频率的作用中起部分作用。接下来，研究了NO对DNA修复和复制系统的影响。DNA依赖性蛋白激酶（DNA-PK）抑制剂渥曼青霉素（Wortmannin）呈剂量依赖性地抑制NO的还原作用，而ATM激酶和ATR激酶抑制剂咖啡因则无此作用。NO处理可增加DNA-PK活性。拓扑异构酶Ⅱ抑制剂足叶乙甙可剂量依赖性地阻断NO降低γ射线诱发的MN频率的作用。上述结果提示，NO影响γ射线诱发的MN频率的机制可能是通过升高GSH和上调DNA-PK活性来修复双链断裂。NO可以作为修复系统的信号，例如用于非同源重组和用于S期的复制系统，以降低MN频率。
Abstract Tokuzumi, S., Hori, M., Monobe, M., Hosoi, Y. and Kojima, S. Effect of Nitric Oxide on γ-Ray-Induced Micronucleus Frequency in RAW264.7 Cells. Radiat. Res. 164, 723–732 (2005). The effect of low-dose nitric oxide (NO) on γ-ray-induced micronucleus (MN) frequency was investigated in RAW264.7 cells. Treatment of RAW264.7 cells with 0.25 mM sodium nitroprusside (SNP), a chemical NO donor, reduced the frequency of micronuclei induced by 5 Gy γ rays by 43 to 45% between 3 and 12 h post-treatment. This effect was blocked by carboxy-PTIO, suggesting that NO may play a role in the reduction of radiation-induced MN frequency. To examine possible mechanisms underlying this effect, we first looked at changes in the antioxidant system after SNP treatment. A significant increase in intracellular glutathione (GSH) was seen in SNP-treated cells between 3 and 12 h post-treatment. Depletion of GSH with buthionine sulfoximine (BSO) increased the γ-ray-induced increase in MN frequency. Detailed studies using various inducers of intracellular GSH suggested that GSH induction has a partial role in the reducing effect of NO on the γ-ray-induced MN frequency. Next, the effect of NO on DNA repair and replication systems was examined. Wortmannin, an inhibitor of DNA-dependent protein kinase (DNA-PK), dose-dependently inhibited the reducing effect of NO, while caffeine, an inhibitor of ATM kinase and ATR kinase, did not. DNA-PK activity was increased by NO treatment. Etoposide, a topoisomerase II inhibitor, dose-dependently blocked the effect of NO in reducing the γ-ray-induced MN frequency. These results suggest that the mechanisms of the effect of NO on the γ-ray-induced MN frequency include elevation of GSH and up-regulation of DNA-PK activity for repairing double-strand breaks. NO may act as a signal for repair systems, e.g. for nonhomologous recombination and for the replication system in S phase, to reduce the MN frequency.