Altered reverse transcriptase-dependent gene diversification mechanisms in Alzheimer's disease brains

项目摘要/摘要 我们已经在人脑的神经元中发现了体细胞基因重组(SGR)，这与 到散发性阿尔茨海默病(SAD)(《自然》杂志，563,639-645(2018))。这一发现代表着一种新的和 基因组嵌合体的功能重要方面(eLife；4：e05116(2015))，具有真正的治疗作用 通过新确定的分子靶标进行潜在的研究。事实上，我们发现作用于AD基因的SGR 淀粉样前体蛋白(APP)，产生数千种不同形式的APP，其中一些富含 或者是AD独有的。到目前为止分析的与AD相关的APP基因变异包括拷贝数 之前报道的变异(CNV)和至少11个单核苷酸变异(SNV) 在家族性AD中致病，但在SAD中以躯体和嵌合体形式出现；这些变异在 未患病的神经元。SGR利用转录的RNA上的逆转录酶(RT)活性，结合 通过DNA链断裂和APP基因转录，产生双链DNA，然后将其反向插入 进入基因组，形成“基因组DNA”(GencDNA)。这些公布的数据为科学研究做出了贡献 目前的提案将建立在此基础上，以测试改变SGR的假设，涉及大脑- 特定的逆转录酶，在功能上与AD有关，并影响多个基因，提供新的靶点 用来治疗AD的。两人有效AD捐赠者的死后IRB批准和未识别的脑样本 性别将与未患病的对照组进行比较，而IACUC批准的动物实验将模拟SGR 及其与AD相关的终端。将在5年内实现三个目标。目标1将定义分子 APP的神经生物学促进了DNA多样性，并确定了在AD大脑中增强的新的SGR基因。目标2将 确定SGR基因在AD脑和模型系统中的表达和功能。AIM 3将识别基因 负责正常和AD脑内RT-SGR的活动。因此，这项提议将为AD打开新的前景 通过新的SGR机制，并将确定治疗AD的新靶点。

PROJECT SUMMARY/ABSTRACT We have identified somatic gene recombination (SGR) in neurons of the human brain, with particular relevance to sporadic Alzheimer’s disease (SAD) (Nature 563, 639-645 (2018)). This discovery represents a new and functionally significant aspect of genomic mosaicism (eLife;4:e05116 (2015)) that has genuine therapeutic potential through newly identified molecular targets. Indeed, we found that SGR, acting on the AD gene for Amyloid Precursor Protein (APP), produces thousands of distinct forms of APP, some of which are enriched in or unique to AD. The APP gene variations related to AD that were analyzed thus far include copy number variations (CNVs) and at least 11 single-nucleotide variations (SNVs) that were previously reported as pathogenic in familial AD, yet that arose somatically and mosaically in SAD; these variations were absent from non-diseased neurons. SGR utilizes reverse transcriptase (RT) activity on transcribed RNAs that, combined with DNA strand-breaks and APP gene transcription, produce double-stranded DNA that is retro-inserted back into the genome to form “genomic cDNAs” (gencDNAs). These published data contribute to the scientific foundation on which the current proposal will build, to test the hypothesis that altered SGR, involving brain- specific reverse transcriptases, functionally contributes to AD and affects multiple genes, providing novel targets for AD therapies. Postmortem IRB-approved and de-identified brain samples from validated AD donors of both sexes will be compared to non-diseased controls, while IACUC-approved animal experiments will model SGR and its AD-relevant endpoints. Three Aims will be pursued over 5 years. Aim 1 will define the molecular neurobiology of APP gencDNA diversity and identify new SGR genes enhanced in AD brains. Aim 2 will determine expression and function of SGR genes in AD brain and model systems. Aim 3 will identify genes responsible for RT SGR activity within normal and AD brains. This proposal will thus open new vistas into AD via novel SGR mechanisms and will identify new therapeutic targets for the treatment of AD.