Gene discovery in PSP by transcriptome, neuropathology and sequence analysis

描述(申请人提供)：进行性核上性麻痹(PSP)是一种快速进行性神经退行性疾病，具有临床病理异质性，没有任何治疗方法。遗传学研究有助于确定PSP风险的分子病理生理学基础及其异质性，这可能使发现治疗靶点成为可能。直到最近，编码tau的MAPT H1单倍型仍是PSP最强的遗传危险因素。一项新的PSP全基因组关联研究发现了另外6个基因座。要将这些发现有效地转化为治疗，需要确定疾病基因、功能变异及其作用机制。这些目标不能仅靠GWA病来实现，需要替代的、强有力的和机械性的方法。目前的建议旨在通过联合分析整个转录组和量化的神经病理学措施来弥合这一知识差距，该方法是在具有良好特征的PSP尸检队列中与现有的GWAS数据相结合的。我们的长期目标是揭示PSP的病理生理学及其亚型的分子底物，最终导致药物发现。鉴于PSP和其他神经性疾病之间的临床病理重叠，我们的建议有望影响广泛的神经退行性疾病，并产生新的治疗途径。我们的中心假设是，许多PSP变体通过调节大脑基因表达来增加风险。此外，不同的转录调控可能是PSP异质性的基础。我们的初步数据确定了一些支持我们假设的顶级PSP GWAS变体的大脑转录关联。在我们的脑库中，我们获得了近500例尸检的PSP患者的脑标本，其中约400例具有典型的临床病理特征，约100例具有不典型的临床病理特征。所有受试者都有临床数据和详细的量化神经病理学指标。我们的目标是在这个独特的队列中获得脑转录组的测量，这些测量将与定量的神经病理学措施一起进行分析，以确定潜在的PSP风险的功能变异及其临床病理异质性，并发现这些变异的作用机制。我们特定目标的预期结果是：1)确定a)影响PSP脑中基因表达的基因变体，b)不仅仅是由于年龄原因的PSP亚型之间的转录水平差异；2)发现同时影响神经病理和PSP基因表达的遗传因素；b)与神经病理学相关的转录本；3)通过a)200个精选PSP大脑样本的下一代RNA测序来揭示PSP的转录调控机制；b)体外翻译研究。所有AIMS的结果将与PSP病GWAS进行比较。这些全面的知识将提名基因及其转录变化作为PSP的新的疾病机制。这些分子机制将构成可修改的药物靶点，从而影响PSP和其他相关的神经退行性疾病。

DESCRIPTION (provided by applicant): Progressive supranuclear palsy (PSP) is a rapidly progressive neurodegenerative disorder with clinicopathologic heterogeneity and without any therapies. Genetic studies can be instrumental in the identification of the molecular pathophysiology underlying PSP risk and its heterogeneity, which may enable discovery of therapeutic targets. Until recently, H1 haplotype of MAPT, encoding tau, was the strongest genetic risk factor for PSP. A new PSP genome-wide association study (GWAS) identified six additional loci. The effective translation of these findings to therapy requires identification of he disease gene, the functional variants and their mechanism of action. These goals cannot be achieved by the disease GWAS alone and require alternative, powerful and mechanistic approaches. The current proposal aims to close this knowledge gap by joint analysis of the whole transcriptome and quantitative neuropathology measures in a well- characterized autopsied PSP cohort with existing GWAS data. Our long-term goal is to uncover the pathophysiology of PSP and the molecular substrates of its subtypes that will ultimately lead to drug discoveries. Given the clinicopathological overlap between PSP and other tauopathies, our proposal is expected to impact a wide range of neurodegenerative disorders and generate novel therapeutic avenues. Our central hypothesis, is that many PSP variants confer risk by regulating brain gene expression. Further, differential transcriptional regulation may underlie the heterogeneity in PSP. Our preliminary data identified brain transcript associations for some of the top PSP GWAS variants supporting our hypothesis. In our Brain Bank, we have access to nearly 500 brain samples from autopsied PSP subjects with existing GWAS, ~400 of which have typical and ~100 with atypical clinicopathology. All subjects have clinical data and detailed quantitative neuropathology measures. Our objective is to obtain brain transcriptome measurements in this unique cohort, which will be analyzed jointly with quantitative neuropathology measures to identify functional variants underlying PSP risk, its clinicopathological heterogeneity and to discover the mechanism of action of these variants. The expected outcomes of our specific aims are: 1) To identify a) genetic variants that influence gene expression in PSP brains, b) transcript level differences between subtypes of PSP that are not simply due to aging; 2) To discover a) genetic factors that influence both neuropathology and gene expression in PSP; b) transcripts that correlate with neuropathology; 3) To uncover the mechanism of transcriptional regulation in PSP by a) next-generation RNA sequencing of 200 select PSP brain samples; b) translational in- vitro studies. Results from all aims will be compared with the PSP disease GWAS. The overall knowledge will nominate genes and their transcriptional changes as novel disease mechanisms in PSP. These molecular mechanisms will constitute modifiable drug targets, which will impact PSP and other related neurodegenerative diseases.