Routledge M N, Wink D A, Keefer L K, Dipple A
Chemistry of Carcinogenesis Laboratory, National Cancer Institute, Frederick Cancer Research and Development Center, MD 21702.
Carcinogenesis. 1993 Jul;14(7):1251-4. doi: 10.1093/carcin/14.7.1251.
Nitric oxide is an important bioregulatory agent that may also be an endogenous and exogenous human mutagen. In order to study mutations generated following exposure of a shuttle vector-borne target gene to nitric oxide, mutations were induced in the supF gene of the pSP189 shuttle vector by treatment with nitric oxide in aerobic buffered solution followed by replication of the plasmid in either human Ad293 or Escherichia coli MBM7070 cells. The induced mutation frequency, which increased with nitric oxide dose, was 44-fold greater than the spontaneous background in human cells and > 15-fold greater than background in the bacterial cells when a total of 100 mmol of nitric oxide was oxidatively absorbed/I of pH 7.4 buffer containing the plasmid. The majority of point mutations analysed (61 and 75% for human and E. coli cells respectively) were AT-->GC transitions with GC-->AT transitions (29 and 23%) being the next most prevalent. The overall frequencies of the various point mutations seen in the supF gene were similar in the two cell types, although the distribution of hotspots showed differences. The results are consistent with a mutational mechanism initiated by deamination of DNA bases.
一氧化氮是一种重要的生物调节因子，也可能是一种内源性和外源性人类诱变剂。为了研究穿梭载体携带的靶基因暴露于一氧化氮后产生的突变，在有氧缓冲溶液中用一氧化氮处理，诱导pSP189穿梭载体的supF基因发生突变，然后在人Ad293细胞或大肠杆菌MBM7070细胞中复制该质粒。当总共100 mmol的一氧化氮被氧化吸收到含有质粒的pH 7.4缓冲液中时，诱导突变频率随一氧化氮剂量增加，在人细胞中比自发背景高44倍，在细菌细胞中比背景高15倍以上。分析的大多数点突变（人细胞和大肠杆菌细胞分别为61%和75%）是AT→GC转换，其次是GC→AT转换（分别为29%和23%）。尽管热点分布存在差异，但在两种细胞类型中，supF基因中观察到的各种点突变的总体频率相似。结果与DNA碱基脱氨基引发的突变机制一致。
