Deregulation of the Ubiquitin/26S Proteasome Pathway in AT cells: Role of ISG15

AT 细胞中泛素/26S 蛋白酶体途径的失调：ISG15 的作用

• 批准号: 7585942
• 负责人: SHYAMAL D DESAI
• 金额: $ 15.53万
• 依托单位: LSU HEALTH SCIENCES CENTER
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2010-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7585942
• 关键词: 26S proteasome; ATM function; ATM gene; Apoptosis; Ataxia; Ataxia Telangiectasia; BRCA1 gene; Biochemical Genetics; Birth; Cell Line; Cells; Clinical; DNA Repair; Defect; Development; Face; Foundations; Future; Genes; Immunologic Deficiency Syndromes; In Vitro; Infection; Inherited; Interferons; Ionizing radiation; Knockout Mice; Link; Malignant Neoplasms; Mediating; Meiosis; Mitotic Checkpoint; Mus; Mutation; Nerve Degeneration; Neuronal Dysfunction; Neurons; Nuclear; Pathogenesis; Pathway interactions; Patients; Phenotype; Phosphotransferases; Predisposition; Prevalence; Protein Overexpression; Public Health; Recurrence; Regulation; Role; Secondary to; Signal Pathway; Spider Veins; TP53 gene; Testing; Tissues; Ubiquitin; Ubiquitin Like Proteins; clinical application; design; ds-DNA; in vivo; inhibitor/antagonist; insight; loss of function mutation; multicatalytic endopeptidase complex; neuron loss; novel; prevent; progressive neurodegeneration; protein degradation; repaired; research study; response; small molecule; telomere

DESCRIPTION (provided by applicant): Ataxia Telangiectasia (A-T) (Boder-Sedgwick/Louis-Bar syndrome) is an inherited immunodeficiency disorder with a prevalence of 1 in 30,000-100,000 births. A-T patients are characterized by pronounced facial spider veins (telangiectsia), recurrent sinopulmonary infections, and an irregular gate (ataxia), which results from progressive neuronal dysfunctions. These clinical presentations, secondary to the sensitivity to ionizing radiation and a marked predisposition to cancer, were explicated in 1995 by Savitsky et al. as an autosomal recessive mutation in the Ataxia Telangiectasia (ATM) gene. ATM is a 370 kDa nuclear Ser/Thr kinase contributing to the regulation of p53, BRCA1, and Chk2 signaling pathways, amongst others, and thus required for progression through mitotic checkpoints, double strand DNA repair, telomere repair, apoptosis, and meiosis. The central role of ATM in cell regulation suggests that loss of function mutations in ATM gene should result in broad pleiotropic effects. In preliminary studies, we have shown that targeted proteasome-mediated degradation is impaired in A-T cells, suggesting that reduce protein turnover in A-T cells could potentially contribute to the A-T phenotype (e.g. neurodegeneration). Our preliminary studies also demonstrated that the reduced protein turnover in A-T cells is associated with elevated expression of ISG15, the Interferon- Stimulated Gene 15, an ubiquitin-like protein proven to antagonize ubiquitin pathway. The present application is comprised of three Specific Aims designed to probe the role of ISG15 in Ataxia Telangiectasia. In the first specific aim, we will investigate the role of ATM in regulating ISG15 expression using various AT cell lines. In the second specific aim, we will test if the elevated expression of ISG15 impairs protein turnover in A-T neurons. Finally, in the third specific aim, we will examine if ISG15-mediated defect in ubiquitin-dependent protein degradation triggers neuronal cell death in vitro (using neurons grown in culture) and in vivo (in Atm -/- mice). The reason(s) for the progressive neurodegeneration in AT patients is not known. Results generated from the proposed experiments will provide insights in to the role of ATM/ISG15 in neurodegeneration in AT. The small molecule inhibitors targeting ISG15 pathway could then be developed in future to prevent ataxia associated with neurodegeneration in AT patients. Thus these studies have potential clinical applications for treating A-T patients. PUBLIC HEALTH RELEVANCE: We plan to test if the elevated expression of ubiquitin-like protein ISG15 is responsible for the neurodegeneration in Ataxia Telangiectasia (A-T). The proof-of-principle experiments described in this proposal will form the foundation for future development of small molecule inhibitors for the ISG15 pathway. These small molecule inhibitors are expected to prevent the ataxia in A-T patients.

描述（由申请人提供）：失调性毛细血管扩张症（a - t） （Boder-Sedgwick/Louis-Bar综合征）是一种遗传性免疫缺陷疾病，患病率为1 / 30,000-100,000。A-T患者的特征是明显的面部蜘蛛静脉（毛细血管扩张），反复发作的肺感染和不规则的门状静脉（共济失调），这是由进行性神经元功能障碍引起的。1995年，Savitsky等人将这些继发于电离辐射敏感性和显著的癌症易感性的临床表现解释为共济失调毛细血管扩张症（ATM）基因的常染色体隐性突变。ATM是一种370 kDa的核丝氨酸/苏氨酸激酶，参与p53、BRCA1和Chk2信号通路的调控，因此需要通过有丝分裂检查点、双链DNA修复、端粒修复、细胞凋亡和减数分裂。ATM在细胞调控中的核心作用表明，ATM基因功能突变的丧失可能导致广泛的多效性效应。在初步研究中，我们发现靶向蛋白酶体介导的降解在A-T细胞中受损，这表明A-T细胞中蛋白质周转的减少可能会导致A-T表型（例如神经变性）。我们的初步研究还表明，A-T细胞中蛋白质周转的减少与ISG15（干扰素刺激基因15）的表达升高有关，ISG15是一种被证明可以拮抗泛素途径的泛素样蛋白。目前的应用包括三个特定目的，旨在探讨ISG15在共济失调毛细血管扩张中的作用。在第一个特定目的中，我们将利用各种AT细胞系研究ATM在调节ISG15表达中的作用。在第二个特定目标中，我们将测试ISG15的表达升高是否会损害A-T神经元中的蛋白质周转。最后，在第三个特定目标中，我们将研究isg15介导的泛素依赖性蛋白降解缺陷是否会在体外（使用培养的神经元）和体内（在Atm -/-小鼠中）引发神经元细胞死亡。AT患者进行性神经退行性变的原因尚不清楚。所提出的实验结果将为ATM/ISG15在AT神经退行性变中的作用提供见解。针对ISG15途径的小分子抑制剂可以在未来开发，以预防AT患者与神经退行性变相关的共济失调。因此，这些研究对治疗A-T患者具有潜在的临床应用价值。公共卫生相关性：我们计划测试泛素样蛋白ISG15的表达升高是否与共济失调毛细血管扩张（A-T）的神经退行性变有关。本提案中描述的原理验证实验将为未来开发ISG15途径的小分子抑制剂奠定基础。这些小分子抑制剂有望预防A-T患者的共济失调。