A unique subpopulation of wild-type neurons recapitulating FAD phenotypes

野生型神经元的独特亚群再现了 FAD 表型

• 批准号: 10559827
• 负责人: Masato Maesako
• 金额: $ 51.87万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-03-01 至 2027-11-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10559827
• 关键词: Age of Onset; Alzheimer' s Disease; Alzheimer' s disease brain; Amyloid beta-Protein; Autopsy; Binding; Biological Assay; Biological Models; Biosensor; Brain; Cell Separation; Cells; Characteristics; Clinical; Cyclic AMP-Dependent Protein Kinases; Data; Data Set; Databases; Development; Disease; FDA approved; Fluorescence Resonance Energy Transfer; Genetic; Genetic Transcription; Goals; Grant; Heterogeneity; Human; Impairment; In Vitro; Individual; Knock-in; Knowledge Portal; Link; Mediating; Molecular; Molecular Conformation; Mus; Mutation; Nerve Degeneration; Neurons; PKA inhibitor; Pathologic; Pathology; Pathway interactions; Persons; Pharmacologic Substance; Phenotype; Phosphorylation; Physiological; Play; Population; Post-Translational Protein Processing; Production; Proteomics; Role; Site; Tg2576; Therapeutic; Time; Tissues; Transgenic Mice; Transgenic Organisms; Vulnerable Populations; brain tissue; early onset; enzyme substrate; familial Alzheimer disease; gamma secretase; in vivo; induced pluripotent stem cell; mouse model; mutant; non-demented; novel; novel therapeutic intervention; novel therapeutics; pharmacologic; presenilin; presenilin-1; resilience; response; sensor; tau Proteins; transcriptomics

Abstract People with late-onset sporadic Alzheimer’s disease (SAD) display overall the same clinical and pathological features as those with early-onset familial AD (FAD). However, the mechanism(s) underlying the clinicopathologic commonality between these two genetically distinct AD forms is unclear. Our overall hypothesis is that a subpopulation of wild-type neurons in the brain strikingly recapitulates the phenotypes of neurons expressing FAD mutant Presenilin (PSEN) (perhaps via post-translational modification of wild-type PSEN1), and this selective cell population plays a role in SAD neurodegeneration. Several pieces of evidence support this hypothesis. First, we showed that wild-type PSEN1 in a subset of neurons within the SAD brain displays a conformation similar to FAD mutant PSEN1 (Wahlster et al. Acta Neuropathol 2013). Second, we uncovered that PKA-mediated PSEN1 phosphorylation at Ser310 is significantly upregulated in SAD brains, and this post translational modification, together with phosphorylation of two other sites, steers wild-type PSEN1 conformation towards that of FAD mutant PSEN1 (Maesako et al. eLife 2017). Lastly, we have recently developed novel genetically encoded FRET-based biosensors that for the first time allow quantitative recording of the gamma-secretase activity over time, on a cell-by-cell basis, in live neurons (Maesako et al. iScience 2020, Houser et al. Sensors 2020, Houser et al. Biosensors 2021, Maesako et al. J Neurosci 2022). Surprisingly, these biosensors have enabled us to discover a unique subpopulation of wild-type neurons displaying diminished endogenous gamma-secretase activity. More importantly, our strong preliminary data show that this cell population recapitulates several key characteristics that have been identified in neurons expressing FAD mutant PSEN; these include impaired gamma-secretase “processivity” and thus predominant production of long Aβ, endo-lysosomal abnormalities, and vulnerability phenotypes in response to toxic insults. Therefore, this proposal will further employ multiple model systems and complementary assays to establish the molecular basis and physiological relevance that support our hypothesis. Aim 1 will elucidate the molecular mechanism(s) underlying the heterogeneity in endogenous gamma-secretase activity and its consequences in neurons. Aim 2 will further verify the cause-and-effect relationship between dysfunctional gamma-secretase, endo-lysosomal abnormalities, and neuronal vulnerability. More importantly, we will explore the therapeutic potential of the US FDA-approved compounds that could potentially function as gamma-secretase modulators (GSMs) or gamma-secretase activators (GSAs). Aim 3 will determine if the unique FAD-like neuronal population exists in “AD” mouse models endogenously expressing wild-type PSEN, as our preliminary results indicate, in iPSCs derived human neurons and post-mortem brains from SAD cases. Given that promoting neuronal resilience could be a new therapeutic strategy for AD, a better understanding of the molecular basis behind the newly discovered selectively vulnerable cell population will open a new path for developing novel therapeutic opportunities.

抽象的 晚发性散发性阿尔茨海默病 (SAD) 患者与早发性家族性 AD (FAD) 患者总体上表现出相同的临床和病理特征，然而，这两种遗传上不同的 AD 形式之间的临床病理学共性的机制是不同的。我们的总体假设是，大脑中的野生型神经元亚群惊人地再现了表达 FAD 突变体早老素 (PSEN) 的神经元的表型（可能通过）。野生型 PSEN1 的翻译后修饰），并且这种选择性细胞群在 SAD 神经变性中发挥作用，有几个证据支持这一假设。与 FAD 突变体 PSEN1 相似的构象（Wahlster 等人 Acta Neuropathol 2013） 其次，我们发现 PKA 介导的 PSEN1 Ser310 磷酸化在SAD 大脑以及这种翻译后修饰与其他两个位点的磷酸化一起，将野生型 PSEN1 构象转向 FAD 突变体 PSEN1 的构象（Maesako 等人，eLife 2017）。最后，我们最近开发了新型基于基因编码的 FRET。生物传感器首次允许在活神经元中逐个细胞地定量记录随时间变化的伽马分泌酶活性（Maesako 等，2017）。令人惊讶的是，这些生物传感器使我们能够发现一种独特的野生型神经元亚群，其表现出内源性γ-分泌酶活性减弱。更重要的是，我们强有力的初步数据表明，该细胞群概括了在神经元中已发现的几个关键特征表达 FAD 突变体 PSEN；这些包括γ-分泌酶“持续合成能力”受损，从而导致长 Aβ 的主要产生、内溶酶体异常以及响应毒性损伤的脆弱表型。目标 1 将阐明内源性 γ 分泌酶活性的异质性及其在神经元中的影响的分子机制。 γ-分泌酶功能失调、内溶酶体异常和神经元脆弱性之间的因果关系更重要的是，我们将探索美国 FDA 批准的可能作为γ-分泌酶调节剂 (GSM) 的化合物的治疗潜力。目标 3 将确定内源性表达野生型 PSEN 的“AD”小鼠模型中是否存在独特的 FAD 样神经元群，正如我们的初步指示结果。 iPSC 源自 SAD 病例的人类神经元和死后大脑。鉴于促进神经元恢复能力可能成为 AD 的新治疗策略，更好地了解新发现的选择性脆弱细胞群背后的分子基础将为开发新的途径开辟新途径。治疗机会。