Analysis of Immunodeficiencies with defective DNA damage response

我们试图分析缺陷的DNA损伤反应导致免疫缺陷的分子机制，这些缺陷作用于包括共济失调-毛细血管扩张症（AT）、Artemis缺陷症和Nijmegen断裂综合征（NBS 1缺陷症）在内的疾病的细胞。到目前为止，我们发现Artemis的S645在DNA损伤试剂作用下被ATM磷酸化。通过这项研究，我们已经表明70 kDa分子与Artemis相关，并控制Artemis的稳定性。这种相互作用需要Artemis的磷酸化，但该位点不在迄今已知的区域内。阿耳忒弥斯的一个新作用也得到了证实。Artemis的核酸内切酶活性被证明是双链DNA断裂所必需的，当DNA复制在一个不规则的链中停滞时。这个过程依赖于ATM。DNA损伤反应（DDR）是免疫受体多样化的必要条件，DDR的破坏导致染色体畸变。我们分析了DDR分子在肿瘤发生中的作用，发现DDR在癌前阶段被激活。在某些情况下，DDR的丧失导致具有p53突变的细胞的恶性转化（Leukemia 2006）ATM和Ku 70/80显示在氧化应激时降解，导致细胞凋亡（Ann NY Acad Sci 2006，Int J Biochem Cell Biol.2008）。14例患者诊断为AT，2例为DNA连接酶IV缺陷，2例为Mre 11缺陷（ATLD），1例为Cernunnos缺陷。最后，我们进行了第一次全国范围的调查AT。我们观察了AT同胞病例之间的表型变化。10%的患者出现高IgM，表明ATM参与了类别转换重组。

We sought to analyze molecular mechanism of immunodeficiency caused by defective DNA damage response working on cells from disorders including ataxia-telangiectasia (AT), Artemis deficiency, and Nijmegen breakage syndrome (NBS1 deficiency).We have so far revealed that S645 of Artemis is phosphorylated by ATM upon DNA damaging reagent. Through this study, we have shown 70-kDa molecule is associated with Artemis and controls stability of Artemis. The interaction requires phosphorylation of Artemis, but the site is not in the hitherto-known region. A new role of Artemis was also demonstrated. Endonuclease activity of Artemis was shown to be required for double strand DNA break when DNA replication is stalled in a ragging strand. This process was dependent on ATM. Further investigation is currently in progress.DNA damage response (DDR) is absolutely required for diversification of immune receptors; and disrupted DDR during the process leads to chromosomal aberration. We analyzed involvement of the DDR molecules in tumorigenesis, and found that DDR is activated in pre-malignant stage. The loss of DDR led to malignant transformation of the cells with mutation in p53 in some cases (Leukemia 2006).ATM and Ku70/80 were shown to be degraded upon oxidative stress leading to cellular apoptosis (Ann NY Acad Sci 2006, Int J Biochem Cell Biol. 2008)。 The cells escaped from apoptosis may lead to acquisition of chromosomal aberration.We diagnosed 14 patients with AT, 2 DNA ligase IV deficiency, 2 Mre11deficiency (ATLD) and one Cernunnos deficiency. Finally, we carried out the first nation-wide survey for AT. We observed phenotypic variety between sibling cases with AT. Hyper-IgM was noted in 10% of the patients indicating involvement of ATM in class switch recombination.