Protein tyrosine nitration and poly(ADP-ribose) polymerase activation in N-methyl-N-nitro-N-nitrosoguanidine-treated thymocytes:: Implication for cytotoxicity
Protein tyrosine nitration and poly(ADP-ribose) polymerase activation in N-methyl-N-nitro-N-nitrosoguanidine-treated thymocytes:: Implication for cytotoxicity
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DOI：
10.1016/j.toxlet.2007.03.007
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发表时间：
2007-05-15
影响因子：
3.5
通讯作者：
Virag, Laszlo
中科院分区：
文献类型：
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作者：
Bai, Peter;Hegedus, Csaba;Virag, Laszlo
1-甲基-3-硝基-1-亚硝基(MNNG)是一种DNA烷基化试剂。DNA被MNNG烷基化后会加速聚(ADP-核糖)代谢。各种亚硝基化合物释放一氧化氮(NO)。因此，我们开始研究MNNG是否作为NO供体发挥作用，以及MNNG来源的NO或过氧亚硝酸盐等次级NO代谢产物是否参与了MNNG诱导的细胞毒性。在水溶液中，MNNG会导致时间和浓度依赖性的NO释放和亚硝酸盐/硝酸盐的生成。此外，在MNNG处理的胸腺细胞中发现各种蛋白质被硝化，这表明MNNG来源的NO可能与细胞内的超氧化物结合形成硝化试剂过氧亚硝酸盐。MNNG还引起胸腺细胞DNA断裂，多聚ADP-核糖聚合酶活性和细胞毒性增加。PARP抑制剂PJ-34、谷胱甘肽(GSH)或N-乙酰半胱氨酸(NAC)可阻止MNNG诱导的DNA损伤(彗星试验)和胸腺细胞死亡(PARP抑制剂PJ-34)。PJ-34针对坏死参数提供的细胞保护与凋亡参数(caspase活性、DNA梯形图)的增加平行，表明PARP激活将凋亡死亡转移到坏死。由于MNNG诱导的细胞毒性与过氧亚硝酸盐诱导的细胞死亡有许多相似之处，我们测试了过氧亚硝酸盐是否至少对MNNG诱导的部分细胞毒性负责。细胞通透性的酶抗氧化剂(超氧化物歧化酶和过氧化氢酶)、NO清除剂cPTIO或过氧亚硝酸根分解催化剂FP15均不能抑制MNNG诱导的DNA断裂和细胞毒性。综上所述，MNNG可诱导胸腺细胞酪氨酸硝化。此外，MNNG通过一种不涉及NO或过氧亚硝酸根的自由基机制损伤DNA。(C)2007爱思唯尔爱尔兰有限公司。保留所有权利。
1-Methyl-3-nitro-1-nitrosoguanidine (MNNG) is a DNA alkylating agent. DNA alkylation by MNNG is known to trigger accelerated poly(ADP-ribose) metabolism. Various nitroso compounds release nitric oxide (NO). Therefore, we set out to investigate whether MNNG functions as NO donor and whether MNNG-derived NO or secondary NO metabolites such as peroxynitrite contribute to MNNG-induced cytotoxicity. MNNG in aqueous solutions resulted in time- and concentration-dependent NO release and nitrite/nitrate formation. Moreover, various proteins in MNNG-treated thymocytes were found to be nitrated, indicating that MNNG-derived NO may combine with cellular superoxide to form peroxynitrite, a nitrating agent. MNNG also caused DNA breakage and increased poly (ADP-ribose) polymerase activity and cytotoxicity in thymocytes. MNNG-induced DNA damage (measured by the comet assay) and thymocyte death (measured by propidium iodide uptake) was prevented by the PARP inhibitor PJ-34 and by glutathione (GSH) or N-acetyleysteine (NAC). The cytoprotection provided by PJ-34 against necrotic parameters was paralleled by increased outputs in apoptotic parameters (caspase activity, DNA laddering) indicating that PARP activation diverts apoptotic death toward necrosis. As MNNG-induced cytotoxicity showed many similarities to peroxynitrite-induced cell death, we tested whether peroxynitrite was responsible for at least part of the cytotoxicity induced by MNNG. Cell-permeable enzymic antioxidants (superoxide dismutase and catalase), the NO scavenger cPTIO or the peroxynitrite decomposition catalyst FP15 failed to inhibit MNNG-induced DNA breakage and cytotoxicity. In conclusion, MNNG induces tyrosine nitration in thymocytes. Furthermore, MNNG damages DNA by a radical mechanism that does not involve NO or peroxynitrite. (C) 2007 Elsevier Ireland Ltd. All rights reserved.