DNA adducts of aristolochic acid II: total synthesis and site-specific mutagenesis studies in mammalian cells
作者:Sivaprasad Attaluri、Radha R. Bonala、In-Young Yang、Mark A. Lukin、Yujing Wen、Arthur P. Grollman、Masaaki Moriya、Charles R. Iden、Francis Johnson
DOI:10.1093/nar/gkp815
日期:2010.1
Aristolochic acids I and II (AA-I, AA-II) are found in all Aristolochia species. Ingestion of these acids either in the form of herbal remedies or as contaminated wheat flour causes a dose-dependent chronic kidney failure characterized by renal tubulointerstitial fibrosis. In ∼50% of these cases, the condition is accompanied by an upper urinary tract malignancy. The disease is now termed aristolochic acid nephropathy (AAN). AA-I is largely responsible for the nephrotoxicity while both AA-I and AA-II are genotoxic. DNA adducts derived from AA-I and AA-II have been isolated from renal tissues of patients suffering from AAN. We describe the total synthesis, de novo, of the dA and dG adducts derived from AA-II, their incorporation site-specifically into DNA oligomers and the splicing of these modified oligomers into a plasmid construct followed by transfection into mouse embryonic fibroblasts. Analysis of the plasmid progeny revealed that both adducts blocked replication but were still partly processed by DNA polymerase(s). Although the majority of coding events involved insertion of correct nucleotides, substantial misincorporation of bases also was noted. The dA adduct is significantly more mutagenic than the dG adduct; both adducts give rise, almost exclusively, to misincorporation of dA, which leads to AL-II-dA→T and AL-II-dG→T transversions.
马兜铃酸 I 和 II(AA-I、AA-II)存在于所有马兜铃属植物中。无论是以草药的形式还是以被污染的小麦粉的形式摄入这些酸,都会导致以肾小管间质纤维化为特征的剂量依赖性慢性肾衰竭。在这些病例中,50%的病例伴有上尿路恶性肿瘤。这种疾病现在被称为马兜铃酸肾病(AAN)。肾毒性主要由 AA-I 引起,而 AA-I 和 AA-II 都具有遗传毒性。从 AAN 患者的肾组织中分离出了 AA-I 和 AA-II 的 DNA 加合物。我们介绍了从 AA-II 中提取的 dA 和 dG 加合物的全合成、特异性位点掺入 DNA 寡聚物以及将这些修饰过的寡聚物拼接到质粒构建体中并转染到小鼠胚胎成纤维细胞中的过程。对质粒后代的分析表明,这两种加合物都能阻止复制,但仍能被 DNA 聚合酶部分处理。虽然大多数编码事件都涉及正确核苷酸的插入,但也发现了大量碱基的错误插入。dA 加合物的致突变性明显高于 dG 加合物;两种加合物几乎都会引起 dA 的错结合,从而导致 AL-II-dA→T 和 AL-II-dG→T 的转换。