Regulation of IL7R splicing by DDX39B and its role in Multiple Sclerosis

DDX39B 对 IL7R 剪接的调节及其在多发性硬化症中的作用

• 批准号: 8832503
• 负责人: Gaddiel Galarza Munoz
• 金额: $ 2.58万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-12-01 至 2015-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8832503
• 关键词: Alleles; Alternative Splicing; Animal Model; Autoimmune Diseases; Autoimmunity; Binding; Biochemical Genetics; Bioinformatics; Boxing; Cells; Cessation of life; Chronic; Code; Collaborations; Complex; Demyelinations; Development; Disease; Disease Association; Disease Outcome; Elements; Etiology; Exons; Family; Family member; Gene Expression; Gene Expression Profiling; Genes; Genetic; Genotype; Goals; Human; IL7 gene; Immunoprecipitation; In Vitro; Individual; Interleukin 7 Receptor; Length; Life; Link; Messenger RNA; Molecular; Multiple Sclerosis; Neuraxis; Neurologic Dysfunctions; Neurons; Nonsense-Mediated Decay; Pathogenesis; Patients; Play; Polypyrimidine Tract-Binding Protein; Positioning Attribute; Predisposition; Production; Protein Isoforms; Proteins; RNA; RNA Helicase; RNA Processing; RNA Splicing; Regulation; Regulator Genes; Reporter; Repression; Research; Risk; Risk Factors; Role; Signal Pathway; Single Nucleotide Polymorphism; Spliceosomes; Susceptibility Gene; Testing; Therapeutic; Therapeutic Intervention; Tissue-Specific Gene Expression; Trans-Activators; Transcription Initiation Site; Work; alpha chain interleukin-7 receptor; base; crosslink; disabling disease; effective therapy; exon skipping; in vivo; novel; protein complex; public health relevance; receptor; research study

 DESCRIPTION (provided by applicant): Multiple Sclerosis (MS) is an autoimmune disorder of the central nervous system typified by axonal demyelination and neuronal death. To date, there is no effective treatment to cure the disease, and the available therapies do not alter the outcome of the disease. The development of better therapeutic options requires in-depth understanding of the molecular mechanisms leading to disease development and progression. Our group previously discovered a single nucleotide polymorphism (SNP, rs6897932) within exon 6 of the IL-7 receptor alpha chain (IL7R) that is strongly associated with the risk of developing MS. Our group further showed that the MS-associated allele of the SNP increases skipping of exon 6 both in vitro and in vivo, leading to increased production of a secreted receptor (sIL7R) that is unable to activate the IL-7 signaling pathway. Importantly, sIL7R has been linked to the disease in both human patients and animal models. These results directly implicate splicing of IL7R to the pathogenesis of MS, and posit the trans-acting factors controlling its splicing as candidate MS susceptibility genes. I have uncovered two of the trans-factors controlling IL7R exon 6 splicing: the RNA helicase DDX39B, which activates exon inclusion, and the polypyrimidine tract binding protein (PTBP1), which represses it. Furthermore, we uncovered several SNPs in the DDX39B gene region that are associated with MS, thereby establishing DDX39B is itself a risk factor for MS. None of the associated SNPs are located within the coding sequence of the gene, suggesting that one or more of these SNPs may contribute to the disease association by modifying DDX39B expression. Through bioinformatics and gene expression analyses, I have uncovered mRNA isoforms encoding either the full-length protein or a novel short protein, and several mRNA isoforms that are candidate targets for nonsense-mediated decay. Importantly, I have established two of the SNPs could alter expression levels of these isoforms. The goal of this proposal is to provide functional links connecting DDX39B to the pathogenesis of MS. Specifically, I aim to: 1) elucidate its role in the regulation of IL7R exon 6 splicing; 2) understand the functional roles of the different protein isoforms; and 3) uncover the SNPs responsible for its association with MS. I will combine biochemical and genetic approaches to elucidate the mechanism by which DDX39B activates exon 6 splicing, and to characterize the functional roles of the protein isoforms. I will test the impact of selected SNPs on DDX39B expression by combining in vivo gene expression analysis and functional studies using reporter minigenes. Successful completion of this research will advance our current understanding of the molecular underpinnings of MS, in particular by functionally linking DDX39B to the pathogenesis of MS, and providing a functional characterization of the DDX39B gene. Given that DDX39B has been associated with numerous autoimmune disorders, our results could be relevant to the mechanistic etiology of other autoimmune diseases.

 描述（申请人提供）：多发性硬化症（MS）是一种以轴突脱髓鞘和神经元死亡为代表的中枢神经系统自身免疫性疾病，迄今为止，还没有有效的治疗方法可以治愈该疾病，并且现有的疗法也不能改变这种疾病。开发更好的治疗方案需要深入了解导致疾病发生和进展的分子机制。 rs6897932）位于 IL-7 受体 α 链 (IL7R) 的外显子 6 内，与发生 MS 的风险密切相关。我们的小组进一步表明，SNP 的 MS 相关等位基因在体外和体内都会增加外显子 6 的跳跃。体内，导致无法激活 IL-7 信号通路的分泌受体 (sIL7R) 的产生增加。重要的是，sIL7R 与人类患者和动物模型中的疾病有关。这些结果直接表明 IL7R 的剪接与 MS 的发病机制有关，并将控制其剪接的反式作用因子作为候选 MS 易感基因，我发现了两个控制 IL7R 外显子 6 剪接的反式因子：RNA 解旋酶 DDX39B，它是 MS 的候选基因。激活外显子包含，以及抑制它的多聚嘧啶束结合蛋白（PTBP1）。此外，我们还发现了几个 SNP。 DDX39B 基因区域与 MS 相关，因此确定 DDX39B 本身就是 MS 的危险因素。相关 SNP 均不位于该基因的编码序列内，表明这些 SNP 中的一个或多个可能通过以下方式促成疾病关联。通过生物信息学和基因表达分析，我发现了编码全长蛋白或新型短蛋白的 mRNA 亚型，以及几种作为候选靶标的 mRNA 亚型。重要的是，我已经确定了两个 SNP 可以改变这些亚型的表达水平，该提案的目标是提供 DDX39B 与 MS 发病机制之间的功能联系。 2) 了解不同蛋白质亚型的功能作用；3) 揭示与 MS 相关的 SNP。我将通过结合体内基因表达分析和使用报告小基因的功能研究来测试选定的 SNP 对 DDX39B 表达的影响。这项研究的成功完成将增进我们目前对 MS 分子基础的理解，特别是通过在功能上将 DDX39B 与 MS 发病机制联系起来，并提供功能性鉴于 DDX39B 与多种自身免疫性疾病相关，我们的结果可能与其他自身免疫性疾病的机制病因学相关。