The role of CELF2 and its genetic variants in Alzheimer's disease

年龄是阿尔茨海默病(AD)最重要的危险因素，但这种疾病的发生 还受环境因素、个体经历和遗传预沉积的影响。遗传因素有 确立了在AD风险中发挥重要作用的作用。CELF2，一种RNA结合蛋白，调节 选择性剪接和RNA稳定性，最近被确定为与AD相关的危险因素。 CELF2基因多态性与APOE的高危等位基因和SNP的“A”等位基因显著相关 Rs2242451与AD风险降低相关。CELF2在神经系统中高度表达，并且 在各种神经退行性变模型中发现神经元CELF2表达水平增强 人类病人。我们产生了一个条件基因敲除的小鼠CELF2等位基因。我们的初步数据表明 删除成人大脑中的CELF2具有有益的效果，包括改善学习和记忆。我们确认了 小鼠CELF2的信使核糖核酸靶点(采用CLIP-SEQ；交联型免疫沉淀高通量 测序)，发现CELF2与一组AD-2的选择性剪接外显子周围的内含子结合 调控基因，包括APP、MAPT(Tau)、PSEN1、PSEN2和BIN1，提示CELF2在 调控AD相关基因的选择性剪接。这些AD相关基因的选择性剪接已知 调控AD发病机制。例如，tau基因外显子10的选择性剪接可以产生蛋白质。 具有三个(3R)或四个(4R)微管结合重复的异构体。仅4R：3R比例的失衡就一直是 已报道足以在人-Tau小鼠模型中诱导AD的发病。与 CELF2 SNP与人类AD风险降低的遗传关联，我们假设CELF2 阿尔茨海默病患者脑组织中CELF2的表达上调，成年患者脑组织中CELF2的缺失足以挽救AD相关疾病 表型。在特定的目标1中，我们将测试CELF2的缺失是否会抑制C. 优雅的广告模特。在特定的目标2中，我们将测试成年大脑中CELF2的缺失是否具有保护性 通过使用AD小鼠模型调节选择性剪接。在具体目标3中，我们将测试CELF2 利用死后人类样本在AD大脑中增加表达，并询问是否降低AD风险的SNP 利用人IPSC来源的神经元下调CELF2的表达或抑制其功能。我们有 获取了死后的大脑样本，并建立了一支拥有遗传学专业知识的强大研究团队， 基因组学，死后阿尔茨海默病的大脑和IPSC。来自拟议工作的数据将提供重要的机制 远远超出已发表的人类基因分析并最终产生新的治疗目标的洞察力 治疗阿尔茨海默病。

Age is the most important risk factor for Alzheimer's disease (AD), but the occurrence of this disease is also affected by environmental factors, individual experience and genetic pre-deposition. Genetic factors are well established to play an important role in risk of AD. CELF2, an RNA binding protein that regulates alternative splicing and RNA stability, has been recently identified as a risk factor associated with AD. Polymorphisms in CELF2 are significantly associated with high-risk alleles of APOE, and the “A” allele of SNP rs2242451 is associated with reduced AD risk. CELF2 is highly expressed in the nervous system, and enhanced neuronal CELF2 expression levels have been found in various neurodegeneration models and human patients. We generated a conditional knockout mouse Celf2 allele. Our preliminary data suggest that deleting Celf2 in adult brain has beneficial effects, including improved learning and memory. We identified mRNA targets of mouse CELF2 (using CLIP-seq; cross-linking immunoprecipitation high-throughput sequencing) and found that CELF2 binds to introns around the alternatively spliced exons of a set of AD- regulated genes, including APP, MAPT (Tau), PSEN1, PSEN2, and BIN1, suggesting a key role of CELF2 in regulating alternative splicing of AD-related genes. Alternative splicing of these AD-related genes is known to regulate AD pathogenesis. For example, alternative splicing of exon 10 of the tau mRNA gives rise to protein isoforms with three (3R) or four (4R) microtubule binding repeats. Imbalances in 4R: 3R ratio alone have been reported sufficient to induce the pathogenesis of AD in a human-Tau mouse model. Taken together with the genetic association between CELF2 SNP and reduced AD risk in humans, we hypothesize that CELF2 expression is up-regulated in AD brains and loss of CELF2 in adult brains is sufficient to rescue AD-related phenotypes. In Specific Aim 1, we will test whether loss of CELF2 can suppress AD-related phenotypes in C. elegans AD models. In Specific Aim 2, we will test whether loss of CELF2 in the adult brain is protective through regulating alternative splicing using AD mouse models. In Specific Aim 3, we will test whether CELF2 expression is increased in AD brains using postmortem human samples and ask if the AD risk-reducing SNP down regulates CELF2 expression or inhibits its function using human iPSC-derived neurons. We have obtained postmortem brain samples and established a strong research team with expertise in genetics, genomics, postmortem AD brains and iPSC. Data from the proposed work will provide important mechanistic insights that go well beyond published human genetic analyses and ultimately yield new therapeutic targets for the treatment of AD.