ProSAAS-mediated neuroprotective mechanisms in Alzheimer's and Parkinson's diseases: the role of secretory chaperones in neurodegeneration

ProSAAS 介导的阿尔茨海默病和帕金森病的神经保护机制：分泌伴侣在神经退行性变中的作用

• 批准号: 10327703
• 负责人: IRIS LINDBERG
• 金额: $ 63.37万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-02-01 至 2023-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10327703
• 关键词: Affect; Alzheimer' s Disease; Alzheimer' s disease model; Alzheimer' s disease related dementia; American; Amyloid; Amyloid beta-Protein; Amyloid deposition; Animal Model; Attenuated; Biochemical; Brain; Cell Line; Cell model; Cells; Client; Corpus striatum structure; Coupled; Cultured Cells; Cytopathology; Cytoplasmic Granules; Cytoprotection; Deposition; Development; Disease; Disease model; Dopamine; Endocrine; Exhibits; Frequencies; Health; Healthcare Systems; Hippocampus (Brain); Homeostasis; In Vitro; Individual; Laboratories; Location; Maintenance; Mediating; Midbrain structure; Modeling; Molecular Chaperones; Motor; Nerve Degeneration; Neurodegenerative Disorders; Neurons; Parkinson Disease; Pathogenicity; Pathology; Pathway interactions; Patients; Peptides; Periodicity; Pick Disease of the Brain; Play; Process; Proteins; Proteomics; Rattus; Role; Scanning; Senile Plaques; Site; Speed; Substantia nigra structure; Synapses; Synaptic Vesicles; Testing; Toxic effect; Tyrosine 3-Monooxygenase; Viral; Work; abeta accumulation; alpha synuclein; amyloid pathology; brain tissue; cytotoxic; cytotoxicity; differential expression; dopaminergic neuron; experimental study; extracellular; immunoreactivity; in vivo; in vivo Model; inhibitor; insight; knock-down; loss of function; mouse model; neuron loss; neuroprotection; neurotoxic; neurotoxicity; older patient; overexpression; potential biomarker; protein aggregation; proteostasis; small hairpin RNA; unpublished works

Demographic considerations predict an overwhelming burden on the U.S. health care system within the next few decades due to an influx of elderly patients with neurodegenerative disease. The most prevalent of these, Alzheimer's and Parkinson's diseases (AD and PD), are predicted to affect tens of millions of Americans by 2040. Both of these diseases involve progressively more aberrant brain proteostasis, associated with massive neuronal cell death. A variety of cytosolic and secreted brain chaperones contribute to maintenance of neuronal proteostasis in these and other neurodegenerative proteinopathies; of these, the secretory chaperone proSAAS has many compelling features. ProSAAS is expressed only in neurons and endocrine cells; because it traffics through the regulated secretory pathway, it becomes concentrated within dense core synaptic granules, and is released during neuronal activity. ProSAAS has been identified by five proteomics groups as a potential biomarker in neurodegenerative disease, and is found associated with aggregated proteins in the substantia nigra of PD patients as well as with amyloid plaques in AD‐affected individuals. ProSAAS blocks the aggregation of both Abeta and alpha synuclein at highly substoichiometric ratios, and both endogenous overexpression as well as exogenous application reduce Abeta‐ and alpha synuclein‐mediated neurotoxicity in primary neurons and cell lines. Most recently, we have shown that proSAAS overexpression is also functionally protective in vivo in a rat model of alpha‐synuclein overexpression. In the proposed work, we will investigate the likely common mechanisms by which proSAAS protects neurons from neurotoxic aggregating proteins and peptides such as alpha synuclein and Abeta 1‐42. We hypothesize that secreted proSAAS sequesters cytotoxic oligomers and fibrils extracellularly, reducing their concentrations at the synapse. Secondly, we hypothesize that endocytosed proSAAS acts intracellularly to similarly sequester cytotoxic proteins, speeding their degradation. Using cultured primary hippocampal and nigral neurons, we will determine whether proSAAS is involved in intracellular and extracellular Abeta and alpha synuclein sequestration. We will also determine whether intracellular expression of proSAAS confers a cytoprotective advantage compared to extracellular addition. Lastly we will assess whether endocytosed proSAAS accelerates the intracellular degradation of Abeta and alpha synuclein. In parallel, we will expand our exciting in vivo results to include the alpha‐synuclein preformed fibril model to tease apart the potential sites of action of proSAAS in substantia nigra and striatum. Pre‐degenerative changes in dopamine homeostasis, assessed using fast‐scan‐cyclic‐voltammetry, will be correlated with proSAAS‐mediated neuroprotection. Similarly, a mouse model of AD will be used to test the effects of proSAAS AAV‐mediated over‐ and underexpression on the development of amyloid pathology. Collectively, these experiments will provide insight into biochemical mechanisms underlying the potent cytoprotective effects of the proSAAS chaperone protein.

人口统计学因素预测，美国医疗保健系统将承受巨大负担， 未来几十年，由于大量老年神经退行性疾病患者的涌入。最 其中流行的阿尔茨海默病和帕金森病（AD和PD）预计将影响数十名 到2040年将有数百万美国人。这两种疾病都涉及越来越多的异常大脑 蛋白质稳态，与大量神经元细胞死亡有关。各种细胞质和分泌的脑 分子伴侣有助于维持这些和其他神经退行性疾病中的神经元蛋白质稳态， 蛋白质病;其中，分泌型伴侣蛋白proSAAS具有许多引人注目的特征。ProSAAS是 仅在神经元和内分泌细胞中表达;因为它通过受调节的分泌细胞运输， 在神经传导通路中，它集中在致密的核心突触颗粒内，并在神经元传导过程中释放。 活动ProSAAS已被五个蛋白质组学小组确定为一种潜在的生物标志物， 神经退行性疾病，并发现与黑质中的聚集蛋白有关， PD患者以及AD患者中的淀粉样斑块。ProSAAS阻止了 A β和α突触核蛋白以高度亚化学计量比聚集， 内源性过表达以及外源性应用降低了原代神经元和细胞系中Abeta和alpha突触核蛋白介导的神经毒性。最近，我们已经表明，proSAAS 过表达在α-突触核蛋白过表达的大鼠模型中也具有体内功能保护性。 在拟议的工作中，我们将调查proSAAS可能的共同机制， 保护神经元免受神经毒性聚集蛋白质和肽如α突触核蛋白和Abeta 1-42我们假设分泌的proSAAS在细胞外螯合细胞毒性寡聚体和原纤维， 降低了它们在突触处的浓度。其次，我们假设内吞的proSAAS作用于 细胞内类似地螯合细胞毒性蛋白，加速其降解。使用培养 原代海马和黑质神经元，我们将确定proSAAS是否参与 细胞内和细胞外A β和α突触核蛋白隔离。我们还将确定 proSAAS的细胞内表达是否赋予细胞保护优势， 胞外添加最后，我们将评估内吞的proSAAS是否加速了细胞内 A β和α突触核蛋白的降解。 与此同时，我们将扩大我们令人兴奋的体内结果，包括α-突触核蛋白预先形成 原纤维模型梳理除了黑质和纹状体中的proSAAS的潜在作用位点。将使用快速扫描循环伏安法评估多巴胺稳态的退行性前变化， 与proSAAS介导的神经保护作用相关。类似地，AD的小鼠模型将用于 检测proSAAS AAV介导的过度表达和低表达对淀粉样蛋白形成的影响， 病理总的来说，这些实验将提供深入了解生化机制 潜在的proSAAS伴侣蛋白的有效的细胞保护作用。