A novel signaling mechanism of Progranulin

颗粒体蛋白前体的新型信号机制

• 批准号: 8533057
• 负责人: Fenghua Hu
• 金额: $ 22.49万
• 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 2015-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8533057
• 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.

描述(申请人提供)：原颗粒蛋白(PGRN)突变，一种编码分泌型糖蛋白的基因，是额颞叶变性伴泛素阳性包涵体(FTLD-U)的主要原因。最近，一种功能未知的II型跨膜蛋白TMEM106B被发现是FTLD-U的危险因素。但PGRN和TMEM106B如何共同作用以预防FTLD-U仍不清楚。我们以前的工作已经确定索蒂林是一种PGRN贩运受体。我们最近的初步数据进一步表明，山梨素在介导PGRN信号转导中发挥了作用。山梨素胞内区缺乏信号基序，提示存在潜在的“共受体”。我们发现TMEM106B与山梨素发生了物理上的相互作用，这种相互作用刺激了TMEM106B的切割。此外，TMEM106B是调节膜内蛋白分解(RIP)的底物，已知RIP在神经元信号转导中发挥关键作用。因此，我们认为山梨素和TMEM106B形成了PGRN的受体复合体，TMEM106B裂解介导了PGRN信号转导。为了验证该模型，提出了两个具体目标。目的：探讨山梨素/TMEM106B在PGRN信号转导中的作用。我们将首先通过测量PGRN对缺乏Sortilin或TMEM106B的神经元的神经营养作用来测试Sortilin和TMEM106B在PGRN信号转导中的重要性。然后我们将确定PGRN信号是否刺激Sortilin/TMEM106B相互作用和TMEM106B切割。目的：探讨TMEM106B的信号转导机制。我们将首先产生一个抗切割版本的TMEM106B，以确定PGRN信号是否需要TMEM106B切割。然后将TMEM106B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。我们还计划通过研究TMEM106B裂解产物的定位和确定其结合伙伴来探讨TMEM106B裂解产物的下游信号机制。综上所述，通过这些研究，我们期望确定山梨素和TMEM106B在PGRN信号转导中的作用，并测试涉及TMEM106B切割的新的信号机制。我们希望我们提出的研究将极大地促进我们对PGRN信号机制的理解，并将建立TMEM106B的第一个分子特征，并阐明其在神经退行性变中的作用。