Molecular regulatory mechanisms of NO analyzed by using nitronyl nitroxide

一氧化氮(NO)被认为与多种疾病的发病机制有关，包括感染、炎症性疾病和癌症。我们已经证明，在癌前和癌组织中，包括特发性肺纤维化和人类肺癌组织中，以及吸烟者的尿中，都存在硝化修饰的核酸(如8-硝基鸟苷和8-硝基鸟氨酸)。在这项研究中，我们鉴定了在炎症细胞因子刺激下，巨噬细胞中形成了新的硝基环核苷酸-8-硝基-3‘，5’-环单磷酸(8-Nitro-c GMP)。8-硝基-cGMP具有cGMP依赖的蛋白激酶激活潜能和不依赖cGMP活性的独特信号功能。非常重要的是8-硝基-cGMP对蛋白质的一种新的翻译后修饰(8-硫代烷氧基-cGMP加合物的形成)，被称为S鸟苷。例如，氧化还原感受器信号蛋白Keap1似乎受到8-硝基-cGMP的调节，通过KEAP 1的高度亲核的半胱氨酸的S鸟苷，导致诱导胁迫适应反应信号。本研究揭示了8-硝基-cGMP是NO的第二信使，为NO和cGMP信号转导的病理生理和化学生物学研究提供了新的领域。

Nitric oxide (NO) has been suggested to be involved in the pathogenesis of various diseases, including infections, inflammatory diseases, and cancer. We have demonstrated the occurrence of nitratively modified nucleic acids (e.g., 8-nitroguanosine and 8-nitroguanine) in precancerous and cancer tissues, including idiopathic pulmonary fibrosis and human lung cancer, and in urine of smokers. In this study, we identified the formation of novel nitrated cyclic nucleotide, 8-nitroguano sine-3', 5'-cyclic monophosphate (8-nitro-c GMP), in macrophages stimulated with inflammatory cytokine. 8-Nitro-cGMP possesses cGMP-dependent protein kinase-activating potential and unique signal functions independent of cGMP activity. Of great importance is a novel post-translational modification (8-thioalkoxy-cGMP adduct formation) of proteins induced by 8-nitro-cGMP, coined S-guanylation. For example, a redox-sensor signal protein Keap 1 appears to be regulated by 8-nitro-cGMP, via S-guanylation of highly nucleophilic Cys sulfhydrils of Keap 1, leading to the induction of stress adaptive response signals. This study revealed 8-nitro-cGMP to be asecond messenger of NO and shed light on new areas of pathophysiology and chemical biology of signal transduction by NO and cGMP.