Progranulin: Mutation and Regulation in Neurodegenerative disease

描述（由申请人提供）：额颞叶变性占所有痴呆症的10-20%，并且由于其与阿尔茨海默病（AD）相比更早的发病年龄以及其对核心人类品质（包括个性，洞察力和语言交流）的巨大影响而具有临床重要性。我们最近发现，编码分泌型生长因子颗粒蛋白前体（PGRN）的基因的功能缺失突变是FTLD最常见病理亚型的重要原因，其特征在于由泛素化TAR DNA结合蛋白43（TDP 43）（FTLD-U）组成的神经元包涵体。我们的工作假设是PGRN突变是比最初预期的更常见的FTLD原因，并且PGRN表达的细微失调可能增加发展FTLD和更广泛的神经退行性疾病的易感性。TDP 43不仅在FTLD-U中，而且在肌萎缩侧索硬化症（ALS）患者和20-30%的病理证实的AD患者中被鉴定为病理蛋白，这支持了这些疾病的统一疾病机制。该项目的具体目标是：1.确定PGRN中突变的完整谱和频率。在全球最大的FTLD患者集合中，我们将进行PGRN的标准化深入突变筛查，并辅以体外功能分析，以确定新突变的疾病意义。2.鉴定PGRN中的调节性顺式作用变体，其改变疾病风险，TDP 43蛋白病的表达或呈现。我们将在FTLD、ALS和AD病例对照人群中进行PGRN的遗传关联研究，并评估常见PGRN遗传变异对基因表达的影响。3.确定miR-659表达和遗传变异在FTLD发生中的作用。我们最近在了解PGRN的调控方面取得了重大进展，我们发现它的表达可以通过特定的microRNA，miR-659来调节。此外，我们已经产生了初步数据，表明位于PGRN的3 'UTR中miR-659预测结合位点的常见遗传变体rs 5848是通过miR-659增强PGRN抑制的FTLD-U的主要风险因素。我们将进行遗传和表达分析，以确定大脑中miR-659表达的失调或编码miR-659的基因中的遗传变异性改变是否可能直接导致FTLD-U的发病机制。所提出的研究与充分认识PGRN突变在FTLD中的作用相关，从而提高诊断准确性和咨询。揭示调节PGRN的遗传和分子途径也可能揭示可用于旨在延迟神经退行性疾病过程的治疗作用的新靶点。 公共卫生相关性：该建议旨在定义FTLD中完整的PGRN突变谱，并确定PGRN表达的细微失调是否可能对更广泛的神经退行性疾病易感。这些研究有助于充分认识PGRN突变在FTLD中的作用，从而提高诊断准确性和咨询。揭示调节PGRN的遗传和分子途径也可能揭示新的治疗靶点，这些靶点可用于旨在延迟神经退行性疾病过程的治疗作用。

DESCRIPTION (provided by applicant): Frontotemporal lobar degeneration represents 10-20% of all dementias and is clinically important because of its earlier age of onset compared to Alzheimer's disease (AD), and its dramatic impact on core human qualities including personality, insight and verbal communication. We recently found that loss-of- function mutations in the gene encoding the secreted growth factor progranulin (PGRN) are an important cause of the most common pathological subtype of FTLD, characterized by neuronal inclusions composed of ubiquitinated TAR DNA-binding protein 43 (TDP43) (FTLD-U). Our working hypothesis is that mutations in PGRN are a more frequent cause of FTLD then initially anticipated and that subtle deregulation of PGRN expression may increase the susceptibility to develop FTLD and a wider range of neurodegenerative diseases. The identification of TDP43 as the pathological protein, not only in FTLD-U, but also in patients with amyotrophic lateral sclerosis (ALS) and in 20-30% of pathologically confirmed AD patients, supports a unifying disease mechanism underlying these disorders. The specific aims of this project are to: 1. Identify the complete spectrum and frequency of mutations in PGRN. In the largest collection of FTLD patients worldwide, we will perform a standardized in- depth mutation screening of PGRN, supplemented with in-vitro functional analyses to determine the disease significance of novel mutations. 2. Identify regulatory cis-acting variants in PGRN that modify disease risk, penetrance or presentation in TDP43 proteinopathies. We will perform genetic association studies of PGRN in FTLD, ALS and AD case-control populations and assess the effect of common PGRN genetic variability on gene expression. 3. Determine the role of miR-659 expression and genetic variability in the development of FTLD. We recently made significant progress in the understanding of the regulation of PGRN when we identified that its expression can be regulated by a specific micro RNA, miR-659. Moreover, we have generated preliminary data suggesting that the common genetic variant rs5848, located in the 3'UTR of PGRN in a predicted binding-site for miR-659, is a major risk factor for FTLD-U through the augmented suppression of PGRN by miR-659. We will perform genetic and expression analyses to determine if deregulation of miR-659 expression in brain or altered genetic variability in the gene encoding miR-659 may contribute directly to the pathogenesis of FTLD-U The proposed studies are relevant to fully appreciate the contribution of PGRN mutations in FTLD leading to increased diagnostic accuracy and counseling. Unveiling the genetic and molecular pathways regulating PGRN may also reveal novel targets that can be exploited for therapeutic actions aimed at delaying the neurodegenerative disease process. PUBLIC HEALTH RELEVANCE: This proposal is designed to define the complete PGRN mutational spectrum in FTLD and to determine whether subtle deregulation of PGRN expression may hold susceptibility to a wider range of neurodegenerative diseases. These studies are relevant to fully appreciate the contribution of PGRN mutations in FTLD leading to increased diagnostic accuracy and counseling. Unveiling the genetic and molecular pathways regulating PGRN may also reveal novel therapeutic targets that can be exploited for therapeutic actions aimed at delaying the neurodegenerative disease process.