Chaperones and their role in the cellular and clinical variability of Nijmegen Breakage Syndrome

奈梅亨断裂综合征是一种罕见的DNA修复缺陷，免疫缺陷和癌症易感性是威胁生命的症状。这种疾病的潜在基因NBN参与了DNA双链断裂的修复，DNA双链断裂是由电离辐射(IR)等引起的。在这里提出的建议中，我们将在国家统计局病理生理学的背景下分析伴侣。伴侣蛋白在压力下的稳定是必不可少的，我们以前的工作表明，伴侣蛋白表达的变化可能会对疾病的临床病程产生根本性的影响。在NBN缺失突变小鼠中，体内照射后HSP60和GRP58等几种伴侣蛋白的表达比对照小鼠增加。另一种伴侣ERp29的行为则不同。这种蛋白在照射后仅在对照组小鼠中上调；在NBN零突变小鼠中，该蛋白没有被诱导。这表明NBN基因产物Nibrin是上调ERp29所必需的。在这里介绍的项目中，将详细研究NBN依赖的ERp29的诱导机制。此外，还将讨论伴侣在NBS患者的临床病程中作为修饰因子的作用。在IR诱导大量NBS细胞系DNA损伤后，将检测伴侣蛋白的表达和活性，并将其与已知的细胞属性以及相应患者的临床病程相关联。同时，我们收集的100多个来自NBS患者的DNA样本将被检测伴侣基因的多态。然后，这些数据也可以与患者的临床数据相关联。

Nijmegen Breakage Syndrome is a rare DNA-Repair deficiency in which immunodeficiency and predisposition to cancer are the life threatening symptoms. The gene underlying the disorder, NBN, is involved in the repair of DNA double-strand breaks which are caused, amongst others, by ionising radiation (IR). In the proposal presented here, we will analyse chaperones within the context of NBS pathophysiology. Chaperones are essential in the stabilisation of proteins under stress and our previous work suggests that variation in the expression of chaperones may have a fundamental impact on the clinical course of the disease. In Nbn null-mutant mice, the expression of several chaperones, such as HSP60 and GRP58, was increased after irradiation in vivo in comparison to control mice. A further chaperone, ERp29, behaved differently. This protein was upregulated after irradiation only in the control mice; in the Nbn null-mutant mice the protein was not induced. This suggests that nibrin, the Nbn gene product, is required for upregulation of ERp29. In the project presented here, the mechanism of NBN-dependent ERp29 induction will be examined in detail. Furthermore, the role of the chaperones as modifying factors in the clinical course of the disease in NBS patients will be addressed. After induction of DNA damage by IR in a large collection of NBS cell lines the expression and activity of chaperones will be examined and correlated with the known cellular properties and, indeed, clinical course of the respective patients. In parallel, our collection of over 100 DNA samples from NBS patients will be examined for polymorphisms in the chaperone genes. These data can then also be correlated with the clinical data of the patients.