MUTATIONAL SPECTRUM OF X-RAY-INDUCED TK- HUMAN CELL MUTANTS
MUTATIONAL SPECTRUM OF X-RAY-INDUCED TK- HUMAN CELL MUTANTS
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DOI：
10.1093/carcin/16.2.267
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发表时间：
1995-02-01
期刊：
影响因子：
4.7
通讯作者：
GROSOVSKY, AJ
中科院分区：
文献类型：
--
作者：
GIVER, CR;NELSON, SL;GROSOVSKY, AJ
电离辐射引起的突变历来引起公众的广泛关注。然而，只有有限的电离辐射引起的点突变数据库可用，特别是在内源性人类细胞位点。在此，我们报告了源自 TK6 人淋巴母细胞的 184 个 X 射线诱导的 TK 突变体的突变谱。该报告首次大规模利用 tk 位点来研究 DNA 序列水平的突变特异性。对 tk 外显子 4 和 7 的移码多态性位点进行快速单核苷酸测序测定，将 TK 突变体分为两组：126 个突变体归因于部分基因缺失或杂合性丧失，并鉴定出 51 个 DNA 序列改变。X 射线诱导的点突变包括所有类别的转换和颠换、串联碱基取代、移码、小缺失和小重复。 tk 内的分布特征是在某些位点聚集。 12 个 TK 点突变（其中 5 个完全位于外显子 3 和 4 的编码序列内）导致 tk 转录本的异常剪接。当将 TK 突变与 TK6 中的 HPRT(-) 突变进行比较时，发现 X 射线诱导的点突变谱具有高度可重复性。与自发背景相比，在组合数据集中观察到转换的统计显着减少（P = 0.04）。这些发现表明了一种可重复的模式，可用于识别其他感兴趣位点的辐射诱导突变。
Mutations induced by ionizing radiation have historically elicited significant public concern. However, only a limited database of ionizing radiation-induced point mutations is available, particularly at endogenous human cell loci. Here, we report the mutational spectrum for 184 X-ray induced TK- mutants derived from TK6 human lymphoblasts. This report represents the first large scale utilization of the tk locus for investigation of mutational specificity at the DNA sequence level. Rapid, single nucleotide sequencing assays at frameshift polymorphism sites in tk exons 4 and 7 were used to partition TK- mutants into two groups: 126 were attributed to either partial gene deletion or to loss of heterozygosity, and DNA sequence alterations were identified for 51. X-ray-induced point mutations included all classes of transitions and transversions, tandem base substitutions, frameshifts, small deletions and a small duplication. The distribution within tk was characterized by clustering at some sites. Twelve TK- point mutations, including five entirely within the coding sequence in exons 3 and 4, resulted in aberrant splicing of the tk transcript. The spectrum of X-ray-induced point mutations was found to be highly reproducible when TK- mutations were compared with HPRT(-) mutations in TK6. A statistically significant decrease in transitions (P = 0.04) was observed in the combined data set as compared to the spontaneous background. These findings suggest a reproducible pattern which may be utilized in recognizing radiation-induced mutations at other loci of interest.