MUTATIONAL RESPONSE OF FANCONI-ANEMIA CELLS TO SHUTTLE VECTOR SITE-SPECIFIC PSORALEN CROSS-LINKS
MUTATIONAL RESPONSE OF FANCONI-ANEMIA CELLS TO SHUTTLE VECTOR SITE-SPECIFIC PSORALEN CROSS-LINKS
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DOI：
10.1093/carcin/16.3.555
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发表时间：
1995-03-01
期刊：
影响因子：
4.7
通讯作者：
BRANT, M
中科院分区：
文献类型：
--
作者：
BREDBERG, A;SANDOR, Z;BRANT, M
范可尼贫血（FA）是一种遗传性肿瘤倾向性疾病。暴露于 DNA 交联剂的 FA 细胞显示染色体畸变和缺失型突变的频率增加。FA 的分子基础可能是 DNA 加合物的细胞修复缺陷。在这项工作中，用 8-甲氧基补骨脂素 + 分次剂量的 UVA 处理穿梭载体质粒（导致交联诱导），并转染到 FA 淋巴母细胞中。载体的supF基因表现出与正常细胞相似的突变频率；然而，碱基取代的数量相对较低，而存在高水平（50%）的缺失。对于正常细胞和 FA 细胞，这些缺失的大小变化很大，并且随机分布在supF基因内，还使用与补骨脂素分子连接并与supF的部分互补的形成22聚体寡核苷酸的三螺旋诱导DNA交联，导致突变增加>30倍，主要是位置167的单碱基取代，并显示出模式与正常细胞相同。 FA细胞对位点特异性DNA交联的这种正常反应可能反映出并非FA细胞的所有基因序列都受到异常DNA修复。或者，它可能反映出DNA交联修复复合物的基因组整体活性低于正常水平，完全能够有效修复仅携带相对较少加合物的分子。
Fanconi anaemia (FA) is a hereditary tumour-prone disorder. FA cells exposed to DNA crosslinking agents show an increased frequency of chromosome aberrations and of deletion type mutations, The molecular basis of FA presumably is a deficiency in cellular repair of DNA adducts, In this work a shuttle vector plasmid was treated with 8-methoxypsolaren + a split dose of UVA (leading to crosslink induction), and transfected into FA lymphoblasts. The supF gene of the vector showed a mutation frequency similar to that of normal cells; however, the number of base substitutions was relatively low whereas a high level (50 %) of deletions was seen, With both normal and FA cells these deletions varied greatly in size and were randomly distributed within the supF gene, DNA cross-links were also induced using a triple helix forming 22-mer oligonucleotide linked to a psoralen molecule and being complementary to part of supF, leading to a >30-fold increase of mutations, which were mainly position 167 single-base substitutions and showed a pattern identical to that of the normal cells. This normal response of FA cells to the site-specific DNA cross-links may reflect that not all gene sequences of FA cells are subjected to abnormal DNA repair, Alternatively, it may reflect a lower than normal genome-overall activity of a DNA cross-link repair complex, fully capable of efficiently repairing only molecules carrying relatively few adducts.