Analysis of Radiation Hypersensitivity of Human Cells From Genetic Disease by the use of Chromosome Transfer

利用微细胞介导的染色体转移技术，对AT(共济失调毛细血管扩张症)细胞辐射敏感性互补基因的染色体定位进行了研究。以永生化AT细胞株AT2KYSV及其6-硫代鸟嘌呤抗性衍生物AT2KYSVTG为受体。用携带单个人染色体的5株小鼠A9细胞作为染色体供体。携带的染色体是PSV2neo标记的人11号染色体、X染色体或X/11重组染色体，其中包含llpterq13、llpterq23或llpl1-qter2。在通过转移PSV2neo标记的11号染色体获得的7个G418抗性微细胞杂交种中，3个克隆表现出辐射抗性的恢复，伴随着额外的11号染色体的获得，而其余的克隆不包含可识别的或缺失的11.3号染色体。通过转移完整的X染色体或带有Ilper-q13区域的X/11染色体获得的抗HAT微细胞杂交细胞与亲本AT细胞在辐射敏感性上没有差异，而通过转移含有LLPL1-QTER或Ilper-q23区域的X/11染色体获得的HAT抗HAT细胞杂交细胞表现出明显的辐射抗性。通过与携带X/11染色体11q1-QTER区的A9株的微细胞融合，进一步获得了一个抗HAT但对辐射敏感的突变体，其中发现了11q23区的缺失。结果表明，补充AT辐射敏感表型的基因位于11号染色体的q23区域。衍生的11号染色体与AT基因座或其功能的缺失有关，可用于与AT基因相关的11q23区域的分子解剖。

The chromosomal localization of the gene which complements radiation hypersensitivity of AT(ataxia telangiectasia)cells was studied by microcell-mediated chromosome transfer.1. An immortalized AT cell line, AT2KYSV, aDd its 6-thioguanineresistant derivative, AT2KYSVTG, were used as recipients. Five strains of mouse A9 cells carrying a single human chromosome were used as chromosome donors. The chromosomes carried were PSV2neo-tagged human chromosome 11, X chromosome, or X/11 recombinant chromosomes containing either llpter-ql3, llpter-q23 or llpll-qter.2. Among seven G418-resistant microcell hybrids obtained from the transfer of a PSV2neo-tagged chromosome 11, three clones showed restoration of radiation resistance with concomitant gain of an extra chromosome 11, while the others contained no recognizable or deleted chromosome 11.3. The HAT-resistant microcell hybrids obtained from the transfer of an intact X chromosome or an X/11 chromosome bearing the Ilpter-ql3 region did not show a diffprence in radiosensitivity from parental AT cells, while those obtained from the transfer of X/11 chromosomes bearing either the llpll-qter or Ilpter-q23 region exhibited a marked radioresistance.4. A HAT-resistant but radiosensitive variant was further obtained from the microcell fusion with an A9 strain carrying an X/11 chromosome bearing llpll-qter region, in which a deletion at the llq23 region was found. The results indicate that the gene which complements a radiosensitive phenotype of AT is located at the q23 region of chromosome 11. The derivative chromosome 11 found here to be associated with concomitant loss of the AT locus or its function would be useful for the molecular dissection of the llq23 region with relevance to the AT gene.