Analysis of homologous DNA recombination using the chicken B-lymphocyte line

该部门现在有一个非常活跃的研究领域的细胞响应DNA损伤，包括DNA修复，DNA降解，细胞凋亡和细胞周期调控的坚实基础。(1)我们已经成功地产生了所有RAD 52上位性组基因中的每一个都有缺陷的DT 40突变体，并且已经发现它们确实涉及HR，包括基因靶向。(2)我们发现，Rad51或Mrell的缺失会导致染色体断裂，就像用X射线照射的野生型DT 40细胞一样。由于HR参与dsb修复，这些观察结果表明，dsb在脊椎动物细胞的细胞周期中频繁发生，HR负责修复这种DNA损伤。(3)我们报告了显着低水平的SCE在所有HR缺陷的细胞系。这是一个重要的发现，因为它首次建立了HR介导的修复和SCE之间的直接相关性。(4)在真核生物中存在两种主要的DNA双链断裂修复途径：非同源末端连接（NHEJ）和HR。我们发现同源DNA重组可以介导姐妹染色单体之间的相互作用，但不能介导同源染色体之间的相互作用，从而修复脊椎动物细胞中的DNA双链断裂。我们的研究对于分析遗传不稳定性导致的肿瘤发生、癌症治疗和基因治疗方法的发展具有重要意义。

The department now has a solid base of very active research in the field of cellular response to DNA damage, including DNA repair, DNA Recombination, apoptosis, and cell cycle regulation.(1) We have successfully generated DT40 mutants deficient in each of all the RAD52 epistasis group genes, and have found they are indeed involved in HR including gene targeting.(2) We found that depletion of either Rad51 or Mrell causes chromosomal breaks like wild-type DT40 cells irradiated with X-rays. Since HR is involved with dsb repair, these observations suggest that dsbs occur frequently during the cell cycle in vertebrate cells and that HR is responsible for repairing such DNA damage.(3) We reported significantly low levels of SCEs in all HR-deficient cell lines. This was an important finding as it established a direct correlation between HR-mediated repair and SCEs for the first time.(4) Two major repair pathways exist in eukaryotes to tackle DNA dsbs : Non-homologous end-joining (NHEJ) and HR.We showed that homologous DNA recombiantion can mediate interactions between sister chromatids but not homologous chromosomes for DNA double-strand break repair in vertebrate cells.Our scudies are relevant to analysis of oncogenesis caused by genetic instability, cancer therapy, and development of methods for gene therapy.