NUP50 as a modifier and risk factor for TDP-43 pathology in FTD/ALS

不溶性和错误折叠的RNA在细胞质中的错误定位和积累- 结合蛋白TDP-43是肌萎缩侧索硬化症(ALS)的神经病理标志 额颞性痴呆(FTD)病谱，但也常见于阿尔茨海默病(AD)和 其他AD相关痴呆(ADRD)，标志着TDP-43错误定位是一种关键的发病机制和高 治疗发展的优先目标。 我们实验室和其他实验室之前的研究已经证实了核孔缺陷和蛋白质输入受损 和RNA输出，作为FTD/ALS和其他与年龄相关的神经退行性疾病的共同标志。而当 越来越多的证据表明，核质运输机制的紊乱与TDP-43有关 病理上，细胞内转运途径与疾病发病机制之间的因果关系不是很好。 明白了。由于之前的研究支持这一提议的前提，我们发现表达 在FTD/ALS模型中使用核孔蛋白NUP50可以恢复TDP-43的溶解度和核定位， 提示NUP50在疾病过程中起着重要作用。这一前提得到了最近的 发现罕见的NUP50变异是ALS的危险因素，以及NUP50在神经元存活中的关键作用。 这些发现使我们假设NUP50在减少蛋白质方面起着非典型的作用 错误定位和聚集，而其在FTD/ALS中的缺陷可能导致TDP-43病理增加， 提示NUP50是治疗发展的一个有前途的靶点。 为了验证这一假设，我们将使用TDP-43细胞、器官类型和动物模型，患者来源的和 诱导多能干细胞(IPSC)来源的神经元与基于质谱学(MS)的结合 人脑组织定量蛋白质组学和免疫组织化学，以阐明NUP50如何减少 TDP-43病理，以及NUP50中ALS/FTD相关突变如何在TDP-43病理中起作用。 在目标1中，我们将有条不紊地研究NUP50对TDP-43异常相变和 错误定位和确定结构域和相关蛋白质在机械性疾病中的作用 在体外对这种活性的了解。在目标2中，我们将确定NUP50对TDP-43依赖的影响 在FTD/ALS小鼠模型中评估NUP50及其相关蛋白作为潜在的神经退行性变 体内治疗靶标。在目标3中，我们将通过以下方式确定NUP50在人类TDP-43蛋白病中的作用 检测NUP50缺乏和疾病相关的NUP50变异对TDP-43病理和病理的影响 评估NUP50在FTD/ALS和ADRD尸检脑组织中的丰度和定位。 我们的发现将通过提供对NUP50如何表达的详细机械理解来影响该领域 可以在疾病模型中影响TDP-43的病理学，并通过确定NUP50在疾病过程中的作用 并验证其作为治疗FTD/ALS和其他ADRD的潜在靶点。

The cytoplasmic mislocalization and accumulation of insoluble and misfolded RNA- binding protein TDP-43 is the neuropathological hallmark of the amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) disease spectrum but is also commonly found in Alzheimer’s disease (AD) and other AD-related dementias (ADRDs), marking TDP-43 mislocalization as a key pathomechanism and high priority target for therapy development. Previous studies from our lab and others have established nuclear pore defects and impaired protein import and RNA export, as a common hallmark of FTD/ALS and other age-related neurodegenerative diseases. While there is growing evidence that perturbations in the nucleocytoplasmic transport machinery are linked to TDP-43 pathology, the causal relationship between intracellular transport pathways and disease pathogenesis is not well understood. As prior research to support the premise of this proposal, we have discovered that expression of the nucleoporin NUP50 in FTD/ALS models can restore solubility and nuclear localization of TDP-43, suggesting an important role for NUP50 in the disease process. This premise is further supported by the recent discovery of rare NUP50 variants as a risk factor for ALS, and a critical role for NUP50 in neuronal survival. These findings lead us to hypothesize that NUP50 serves in a non-canonical role in reducing protein mislocalization and aggregation, while its deficiency in FTD/ALS may lead to increased TDP-43 pathology, suggesting NUP50 as a promising target for therapy development. To test this hypothesis, we will use TDP-43 cellular, organotypic and animal models, patient-derived and induced pluripotent stem cell (iPSC)-derived neurons, in combination with mass spectrometry (MS)-based quantitative proteomics and immunohistochemistry in human brain tissue, to elucidate how NUP50 can reduce TDP-43 pathology, and how ALS/FTD-associated mutations in NUP50 contribute towards TDP-43 pathology. In Aim 1 we will methodically investigate the effect of NUP50 on aberrant TDP-43 phase transition and mislocalization and establish the role of structural domains and associated proteins for a mechanistic understanding of this activity in vitro. In Aim 2 we will determine the effect of NUP50 on TDP-43-dependent neurodegeneration in FTD/ALS mouse models, to evaluate NUP50 and associated proteins as a potential therapeutic targe in vivo. In Aim 3, we will establish the role of NUP50 in human TDP-43 proteinopathies, by testing the effect of NUP50 deficiency and disease-associated NUP50 variants on TDP-43 pathology and assessing the abundance and localization of NUP50 in FTD/ALS and ADRD autopsy brain tissue. Our findings will impact the field by providing a detailed mechanistic understanding of how NUP50 expression can impact TDP-43 pathology in disease models, and by establishing the role of NUP50 in the disease process and validating it as a potential therapeutic target in FTD/ALS and other ADRDs.