A novel signaling mechanism of Progranulin

颗粒体蛋白前体的新型信号机制

• 批准号: 8425524
• 负责人: Fenghua Hu
• 金额: $ 19.3万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2014-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8425524
• 关键词: Accounting; Alzheimer' s Disease; Binding; Biological Assay; Bypass; Cell Line; Cell surface; Cells; Complex; Data; Dementia; Development; Endocytosis; Event; Frontotemporal Lobar Degenerations; Genes; Genetic Polymorphism; Glycoproteins; Goals; Integral Membrane Protein; Maps; Measures; Mediating; Modeling; Molecular; Motor Neurons; Mus; Mutation; Nerve Degeneration; Neurons; PGRN gene; Patients; Peptides; Pharmaceutical Preparations; Play; Progranulin; Proteolysis; Resistance; Risk Factors; Role; Signal Transduction; Site; Subfamily lentivirinae; Testing; Therapeutic; Ubiquitin; Work; early onset; genetic linkage; granulin; neuronal survival; novel; prevent; protein TDP-43; protein aggregate; receptor; small hairpin RNA; sortilin; trafficking

DESCRIPTION (provided by applicant): Mutations in Progranulin (PGRN), a gene encoding a secreted glycoprotein, are the major cause of Frontotemporal Lobar Degeneration with ubiquitin positive inclusions (FTLD-U). More recently, TMEM106B, a type II transmembrane protein of unknown function, was discovered as a risk factor of FTLD-U. But how PGRN and TMEM106B function together to prevent FTLD-U remains unclear. Our previous work has identified sortilin as a PGRN trafficking receptor. Our recent preliminary data further suggests that sortilin plays a role in mediating PGRN signaling. Lack of a signaling motif in sortilin intracellular region suggests the presence of a potential 'co-receptor". We found that TMEM106B physically interacts with sortilin and this interaction stimulates the cleavage of TMEM106B. Furthermore, TMEM106B is a substrate of regulated intramembrane proteolysis (RIP), which is known to play a critical role in neuronal signal transduction. Thus we propose that sortilin and TMEM106B form a receptor complex for PGRN and TMEM106B cleavage mediates PGRN signaling. To test this model, two specific aims are proposed. Aim1: To determine the role of sortilin/TMEM106B in PGRN signaling. We will first test the importance of sortilin and TMEM106B in PGRN signaling by measuring the neurotrophic effects of PGRN in neurons lacking sortilin or TMEM106B. Then we will determine whether PGRN signaling stimulates sortilin/TMEM106B interaction and TMEM106B cleavage. Aim2: To investigate the signaling mechanism of TMEM106B. We will first generate a cleavage resistant version of TMEM106B to determine whether TMEM106B cleavage is required for PGRN signaling. Then the cleavage product of TMEM106B will be expressed in NSC-34 cells to determine whether it has neurotrophic effects similar to PGRN treatment. We also plan to probe the downstream signaling mechanisms of TMEM106B cleavage product by examining its localization and identifying its binding partners. In summary, through these studies, we expect to establish a role of sortilin and TMEM106B in PGRN signaling and test a novel signaling mechanism involving TMEM106B cleavage. We expect our proposed studies will significantly advance our understanding on PGRN signaling mechanisms and will establish the first molecular characterization of TMEM106B and illustrate its role in neurodegeneration. PUBLIC HEALTH RELEVANCE: Mutations in the PGRN gene are the main cause of Frontotemporal Lobar Degeneration with protein aggregates containing TDP-43 (FTLD-U). We aim to test a novel hypothesis in which PGRN promotes neuronal survival through a receptor complex comprised of sortilin and TMEM106B, the newly identified risk factor for FTLD-U. We propose that the cleavage of TMEM106B plays a critical role in signaling.

描述（由申请方提供）：颗粒蛋白前体（PGRN）（一种编码分泌型糖蛋白的基因）突变是额颞叶变性伴泛素阳性包涵体（FTLD-U）的主要原因。最近，TMEM 106 B，一种功能未知的II型跨膜蛋白，被发现是FTLD-U的危险因素。但PGRN和TMEM 106 B如何共同发挥作用以防止FTLD-U仍不清楚。我们以前的工作已经确定分拣蛋白作为PGRN运输受体。我们最近的初步数据进一步表明分拣蛋白在介导PGRN信号传导中起作用。分拣蛋白胞内区域信号基序的缺失提示了潜在的“辅助受体”的存在。我们发现TMEM 106 B与分拣蛋白物理相互作用，并且这种相互作用刺激TMEM 106 B的切割。此外，TMEM 106 B是受调节的膜内蛋白水解（RIP）的底物，已知其在神经元信号转导中起关键作用。因此，我们提出分拣蛋白和TMEM 106 B形成PGRN的受体复合物，并且TMEM 106 B切割介导PGRN信号传导。为了测试这个模型，提出了两个具体的目标。目的1：研究分拣蛋白/TMEM 106 B在PGRN信号转导中的作用。我们将首先通过测量PGRN在缺乏分拣蛋白或TMEM 106 B的神经元中的神经营养作用来测试分拣蛋白和TMEM 106 B在PGRN信号传导中的重要性。然后我们将确定PGRN信号传导是否刺激分拣蛋白/TMEM 106 B相互作用和TMEM 106 B切割。目的2：探讨TMEM 106 B的信号转导机制。我们将首先产生TMEM 106 B的切割抗性形式以确定PGRN信号传导是否需要TMEM 106 B切割。然后将TMEM 106 B的切割产物在NSC-34细胞中表达，以确定其是否具有与PGRN处理类似的神经营养作用。我们还计划通过检测TMEM 106 B切割产物的定位和鉴定其结合伴侣来探索其下游信号传导机制。总之，通过这些研究，我们期望建立分拣蛋白和TMEM 106 B在PGRN信号传导中的作用，并测试涉及TMEM 106 B切割的新信号传导机制。我们希望我们提出的研究将显著推进我们对PGRN信号传导机制的理解，并将建立TMEM 106 B的第一个分子表征，并说明其在神经退行性变中的作用。 公共卫生相关性：PGRN基因突变是额颞叶变性的主要原因，其中蛋白质聚集体含有TDP-43（FTLD-U）。我们的目的是测试一种新的假设，其中PGRN通过由分拣蛋白和TMEM 106 B组成的受体复合物促进神经元存活，TMEM 106 B是新发现的FTLD-U的风险因素。我们认为TMEM 106 B的裂解在信号传导中起着关键作用。