A Forgotten Connection: Retrotransposon contribution to Alzheimer's Disease

现有R01的一个目标是开发一种高通量方法，称为 Score，用于检测人类DNA中的多态L1S(PL1S)反转录转座子。我们现有的 R01不包括任何涉及分析阿尔茨海默病(AD)专利的研究 基因组。然而，这种分析将在本R01的范围内，因为pL1及其 DNA损伤是资助的R01和拟议的管理部门的共同主题 副刊。这项拟议的研究对AD很重要，因为AD患者的大脑 与年龄匹配的对照组相比，DNA断裂水平增加，证据支持这一点 这种损伤导致AD临床前阶段的神经元丢失，此时斑块和缠结 还没有形成。因此，确定神经元丢失的另一个机制(S) 将极大地提高我们对AD病因和治疗进展的理解 发展。有几种分子机制可以防止L1相关的损伤。其中一人 是一种由TRIM28介导的通过表观遗传沉默L1启动子来抑制L1表达的过程。 尽管TRIM28在整个大脑的神经元中都有表达，但L1损伤发生在 海马区和大脑皮层，这也是AD患者受影响的区域。我们的 初步发现，与其在抑制L1转录中的作用无关，TRIM28 与L1蛋白相互作用，刺激L1逆转录转座。 我们假设AD患者的基因组比正常人的基因组含有更多的pL1 受试者，这可能导致与L1相关的增加相关的神经元丢失 DNA损伤，特别是当与TRIM28的放松管制结合在一起时。我们将检验我们的假设 通过两个具体目标。AIM 1将进行一项病例对照研究，以确定 阿尔茨海默病患者(例)和年龄匹配的非认知受试者基因组中的pL1 损害(对照)。这一目标将决定pL1的数量和/或构成是否 与AD关联。目标2将确定TRIM28与L1 ORF2p的相互作用机制 蛋白质及其对L1整合和DSB形成的影响。这一目标将决定是否 TRIM28在L1扩增周期和TRIM28相关机制中起双重作用 刺激L1逆转位。这些目标的综合积极结果将证明 大规模研究测试基因组L1含量在确定个体发病风险中的作用 发展为阿尔茨海默病和/或其他与年龄相关的痴呆。

One goal of the existing R01 is the development of a high throughput method, called SCORE, for detection of polymorphic L1s (pL1s) retrotransposons in human DNA. Our existing R01 does not include any studies involving analysis of Alzheimer's Disease (AD) patents' genomes. However, such analysis would be within the scope of this R01 because pL1s and their DNA damage are a common theme of both the funded R01 and the proposed Administrative Supplement. The proposed research is important to AD because brains of AD patients have increased levels of DNA breaks compared to age-matched controls with evidence supporting that this damage leads to neuronal loss at the pre-clinical stage of AD when plaques and tangles have not yet been formed. Thus, identification of an additional mechanism(s) underlying neuronal loss will significantly improve our understanding of AD etiology and progress in treatment development. Several molecular mechanisms guard against L1-associated damage. One of them is a TRIM28-mediated suppression of L1 expression by epigenetic silencing of L1 promoters. Although TRIM28 is expressed in neurons throughout the brain, L1 damage occurs in hippocampus and cerebral cortex, which are the areas that are also affected in AD patients. Our preliminary findings show that, independent of its role in suppression of L1 transcription, TRIM28 interacts with L1 proteins and stimulates L1 retrotransposition. We hypothesize that genomes of AD patients have more pL1s than genomes of normal subjects, which can contribute to the neuronal loss associated with an increase in L1-associated DNA damage, especially when combined with deregulation of TRIM28. We will test our hypothesis through two specific aims. Aim 1 will perform a case-control study to determine the number of pL1s in the genomes of AD patients (case) and age-matched subjects without cognitive impairment (control). This aim will determine whether the number and/or composition of pL1s is associated with AD. Aim 2 will determine the mechanism of TRIM28 interaction with L1 ORF2p protein and its effect on L1 integration and DSB-formation. This aim will determine whether TRIM28 plays a dual role in the L1 amplification cycle and the mechanism of TRIM28-associated stimulation of L1 retrotransposition. Combined positive outcomes of these aims would justify large-scale studies testing the utility of genomic L1 content in identifying individual risk of developing AD and/or other age-related dementias.