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 患有晚期发病的阿尔茨海默氏病（SAD）的人总体上表现出与早期发作家族广告（FAD）的临床和病理特征相同的临床和病理特征。然而，这两种遗传学不同的AD形式之间的临床病理通用性的基础机制尚不清楚。我们的总体假设是，大脑中野生型神经元的亚群可以概括表达FAD突变蛋白的神经元的表型（PSEN）（也许是通过野生型PSEN1的翻译后修饰），并且这种精选细胞在SAD神经降解中起作用。一些证据支持这一假设。首先，我们表明，SAD大脑中神经元子集中的野生型PSEN1显示出类似于FAD突变体PSEN1的构象（Wahlster等人Acta Neuropathol 2013）。其次，我们发现SER310处的PKA介导的PSEN1磷酸化在SAD大脑中有显着更新，并且这篇文章将修改以及其他两个站点的磷酸化，偷窃者野生型PSEN1会议转换为FAD MUTANT PSEN1的野生型PSEN1会议（Maesako等人2017年）。最后，我们最近开发了基于遗传编码的新型基于FRET的生物传感器，该生物传感器首次允许在活神经元中逐个细胞的γ-分泌酶活性进行定量记录（Maesako等人Iscience 2020年2020年，Houser等人2020，Houser等人2020，Houser等人2020年，Houser等人，Houser等人20221222 NE22 NE. JESAKI AL。JESAKI AL。JESAKI。令人惊讶的是，这些生物传感器使我们能够发现野生型神经元的独特亚群，表现出降低的内源性γ-分泌酶活性。更重要的是，我们强大的初步数据表明，该细胞种群概括了在表达FAD突变体PSEN的神经元中已鉴定出的几个关键特征。其中包括受损的γ-分泌酶“加工性”，从而主要产生长Aβ，内部溶质体异常和脆弱性表型，以响应有毒感染。因此，该建议将进一步员工多个模型系统和完整的测定，以建立支持我们假设的分子基础和物理相关性。 AIM 1将阐明内源性γ-分泌酶活性中异质性及其在神经元中的后果的分子机制。 AIM 2将进一步验证功能失调的γ-分泌酶，内部溶血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批准的化合物的治疗潜力，这些化合物可能有可能充当γ-分泌酶调节剂（GSMS）或伽马分泌酶激活剂（GSAS）。 AIM 3将确定在内源表达野生型PSEN的“ AD”小鼠模型中是否存在独特的FAD样神经元种群，正如我们的初步结果表明，在IPSC中，IPSC衍生出人类神经元和来自SAD病例的死亡后大脑。鉴于促进神经元的弹性可能是AD的新理论策略，因此对新发现的被选为脆弱的细胞种群背后的分子基础有更好的理解将为开发新的治疗机会开辟新的途径。