Deletion and single nucleotide substitution at G:C in the kidney of gpt delta transgenic mice after ferric nitrilotriacetate treatment
Deletion and single nucleotide substitution at G:C in the kidney of gpt delta transgenic mice after ferric nitrilotriacetate treatment
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DOI：
10.1111/j.1349-7006.2006.00301.x
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发表时间：
2006-11-01
期刊：
影响因子：
5.7
通讯作者：
Toyokuni, Shinya
中科院分区：
文献类型：
--
作者：
Jiang, Li;Zhong, Yi;Toyokuni, Shinya
一种铁螯合物，次氮基三乙酸铁（Fe-NTA），诱导氧化性肾近端小管损伤，随后导致高发病率的肾细胞癌在啮齿动物，提出了一个有趣的模型，自由基诱导的致癌作用。在本研究中，我们使用gpt delta转基因小鼠，它允许在体内点突变和缺失的有效检测，以评估突变谱，与形成8-氧代鸟嘌呤和丙烯醛修饰的腺嘌呤在前3周的癌变。免疫组织化学分析显示，重复给药1周后，肾近端小管中8-氧代鸟嘌呤和丙烯醛修饰的腺嘌呤水平最高。DNA免疫沉淀和定量聚合酶链反应分析表明，8-氧代鸟嘌呤和丙烯醛修饰的腺嘌呤在gpt报告基因的相对丰度增加，在第一周的肾脏。类似地，在Fe-NTA给药后对肾脏标本进行的6-硫鸟嘌呤和Spi（-）选择中，在第一周Fe-NTA给药小鼠中突变频率增加。对79个突变克隆和93个阳性噬斑的进一步分析显示，G：C对作为点突变的优选靶点的频率很高，特别是G：C至C：G的颠换型突变，随后是缺失，以及在连接处的重复序列附近具有短同源序列的大尺寸（> 1个内切酶）缺失。结果表明，铁基芬顿反应在肾小管细胞中是体内致突变的，并诱导特征性突变。
An iron chelate, ferric nitrilotriacetate (Fe-NTA), induces oxidative renal proximal tubular damage that subsequently leads to a high incidence of renal cell carcinoma in rodents, presenting an intriguing model of free radical-induced carcinogenesis. In the present study, we used gpt delta transgenic mice, which allow efficient detection of point mutations and deletions in vivo, to evaluate the mutation spectra, in association with the formation of 8-oxoguanine and acrolein-modified adenine during the first 3 weeks of carcinogenesis. Immunohistochemical analysis revealed the highest levels of 8-oxoguanine and acrolein-modifed adenine in the renal proximal tubules after 1 week of repeated administration. DNA immunoprecipitation and quantitative polymerase chain reaction analysis showed that the relative abundance of 8-oxoguanine and acrolein-modified adenine at the gpt reporter gene were increased at the first week in the kidney. Similarly, in both 6-thioguanine and Spi(-) selections performed on the renal specimens after Fe-NTA administration, the mutant frequencies were increased in the Fe-NTA-treated mice at the first week. Further analyzes of 79 mutant clones and 93 positive plaques showed a high frequency of G:C pairs as preferred targets for point mutation, notably G:C to C:G transversion-type mutation followed by deletion, and of large-size (> 1 kilobase) deletions with short homologous sequences in proximity to repeated sequences at the junctions. The results demonstrate that the iron-based Fenton reaction is mutagenic in vivo in the renal tubular cells and induces characteristic mutations.