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

奈亨断裂综合征是一种罕见的dna修复缺陷，其免疫缺陷和易患癌症是危及生命的症状。这种疾病背后的基因NBN参与DNA双链断裂的修复，这种断裂是由电离辐射（IR）引起的。在这里提出的建议中，我们将在NBS病理生理学的背景下分析伴侣。伴侣在压力下的蛋白质稳定中是必不可少的，我们之前的工作表明伴侣表达的变化可能对疾病的临床过程有根本性的影响。在Nbn零突变小鼠中，与对照小鼠相比，辐照后体内几种伴侣蛋白（如HSP60和GRP58）的表达增加。另一个伴侣，ERp29，表现不同。该蛋白仅在对照组小鼠中辐照后表达上调；在Nbn零突变小鼠中，该蛋白未被诱导。这表明Nbn基因产物nibrin是ERp29上调所必需的。在这里提出的项目中，将详细研究nbn依赖性ERp29诱导的机制。此外，伴侣作为修饰因子在NBS患者的临床病程中的作用将被解决。在大量NBS细胞系中，IR诱导DNA损伤后，将检查伴侣蛋白的表达和活性，并将其与已知的细胞特性以及相应患者的临床病程相关联。同时，我们收集的来自NBS患者的100多个DNA样本将用于检测伴侣基因的多态性。这些数据还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.