微细胞介导染色体转移法提高AT5 BIVA细胞对电离辐射的抗性

ＡＴ５ＢＩＶＡ细胞是一株经ＳＶ４０病毒转化的ＡＴ病人皮肤成纤维细胞，对γ射线高度敏感。实验用ＦＤ３（含人第１１号染色体的人鼠杂种细胞）、ＦＤ８（不含人第１１号染色体的人鼠杂种细胞）、ＬＭ／ＴＫ鼠细胞）为洪体，通过微细胞介导染色体转移（ＭＭＣＴ）向ＨＴ５ＢＩＶＡ细胞导入人或鼠的完整染色体，经两次３Ｇｙγ射线照射筛选后，获得ＡＴ５ＢＩＶＡ与ＦＤ３微细胞融合的杂合细胞ＡＴ／ＦＤ３－１，对γ射线抗性有显著提高。而ＦＤ８或ＬＭ／ＴＫ的微细胞与ＡＴ５ＢＩＶＡ细胞的杂合细胞，对γ射线抗性未增加。枝型分析表明ＡＴ／ＦＤ３—１细胞中包含了来源于ＦＤ３细胞的人第１１，１４号染色体和数条鼠染色体。通过对照实验，排除了人１４号和鼠染色体提高ＡＴ／ＦＤ３－１细胞对γ射线抗性的可能性．确认人第１１号染色体与ＡＴ细胞对电离辐射敏感性相关，提示人第１１号染色体上可能存在决定细胞对γ射线抗性的相关基因。

INCREASE OF RESISTANCE TO IONIZING RADIATION IN AT 5 BIVA CELLS BY MICROCELL-MEDIATED CHROMOSOME TRANSFER

Ataxia-telangiectasia (AT) is a rare human autosomal recessivedisease characterized by hypersensitivity to ionizing radiation, neurological disorders, immunodeficiency, chromosomal instability and a high incidence of cancers.It was thought that the cause for hypersensitivity was due to the putative DNA repair gene deficiency. Recently. studies on genetic linkage analysis of families with. AT carriers had suggested that a genetic defect in a region of chromosome 11 q 22-23 was responsible for the AT disorder. The SV 40--transformed ATSBIVA cells(group D), from skin fibroblast of AT patients, was hypersensitive to Gamma--ray. The karyotype analysis had previously shown there were abnormalities of chromosome 11, 13, 14, 15 and 22 in ATSBIVA cells. In order to study the molecular mechanism of hyper--radiosensitivity in AT cells and to map DNA repair gene, a new strategy to introduce intact chromosomes into AT 5 BIVA cells by the technique of microcell--mediated chromosome transfer(MMCT) was used.Two human x mouse hybrid cells(FD 3 and FD 8) and a mouse cell line(LM/ TK-) were used. FD 3 cells contain human chromosome 11 while FD & does not.The microcells of these three cell lines were prepared and fused with AT 5 DIVA cells. After twice selection by 3 Gy V- irradiation, the clones which were resistant to y--irradiation were isolated. AT/FD 3--1 cells, the AT 5 BIVA x FD 3 mircocell fused hybrid, showed enhancement of radioresistance. Karyotype analysis had also shown AT/FD 3-1 cells contained an additional copy of chromosome 11. The results indicated the genes responsible for cell resistance to ionizing irradiation existed in human chromosome 11.