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

目前，该系在DNA损伤的细胞反应研究领域有着坚实的基础，包括DNA修复、DNA重组、细胞凋亡和细胞周期调控。(1)我们成功生成了RAD52上位性组所有基因缺失的DT40突变体，并发现它们确实参与了HR包括基因靶向。(2)我们发现Rad51或Mrell的缺失引起的染色体断裂与x射线照射的野生型DT40细胞相似。由于HR参与了dsb的修复，这些观察结果表明，dsb在脊椎动物细胞的细胞周期中经常发生，而HR负责修复这种DNA损伤。(3)我们报道了所有hr缺陷细胞系中显著低水平的SCEs。这是一个重要的发现，因为它首次建立了hr介导的修复与sce之间的直接相关性。(4)真核生物存在两种主要的修复途径：非同源末端连接（Non-homologous end-joining， 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对脊椎动物细胞DNA双链断裂修复的作用。我们的研究涉及基因不稳定性引起的肿瘤发生分析、癌症治疗和基因治疗方法的发展。

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.