Department of Chemistry and Biochemistry, School of Mathematics and Natural Sciences, University of Southern Mississippi, Hattiesburg, Mississippi, USA; Center for Molecular and Cellular Biosciences, University of Southern Mississippi, Hattiesburg, Mississippi, USA.
School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA.
J Biol Chem. 2022 Nov;298(11):102498. doi: 10.1016/j.jbc.2022.102498. Epub 2022 Sep 16.
Amyloid aggregates of specific proteins constitute important pathological hallmarks in many neurodegenerative diseases, defining neuronal degeneration and disease onset. Recently, increasing numbers of patients show comorbidities and overlaps between multiple neurodegenerative diseases, presenting distinct phenotypes. Such overlaps are often accompanied by colocalizations of more than one amyloid protein, prompting the question of whether direct interactions between different amyloid proteins could generate heterotypic amyloids. To answer this question, we investigated the effect of α-synuclein (αS) on the DNA-binding protein TDP-43 aggregation inspired by their coexistence in pathologies such as Lewy body dementia and limbic predominant age-related TDP-43 encephalopathy. We previously showed αS and prion-like C-terminal domain (PrLD) of TDP-43 synergistically interact to generate toxic heterotypic aggregates. Here, we extend these studies to investigate whether αS induces structurally and functionally distinct polymorphs of PrLD aggregates. Using αS-PrLD heterotypic aggregates generated in two different stoichiometric proportions, we show αS can affect PrLD fibril forms. PrLD fibrils show distinctive residue level signatures determined by solid state NMR, dye-binding capability, proteinase K (PK) stability, and thermal stability toward SDS denaturation. Furthremore, by gold nanoparticle labeling and transmission electron microscopy, we show the presence of both αS and PrLD proteins within the same fibrils, confirming the existence of heterotypic amyloid fibrils. We also observe αS and PrLD colocalize in the cytosol of neuroblastoma cells and show that the heterotypic PrLD fibrils selectively induce synaptic dysfunction in primary neurons. These findings establish the existence of heterotypic amyloid and provide a molecular basis for the observed overlap between synucleinopathies and TDP-43 proteinopathies.
特定蛋白质的淀粉样物聚集体构成了许多神经退行性疾病的重要病理学特征，定义了神经元变性和疾病发作。最近，越来越多的患者表现出多种神经退行性疾病的合并症和重叠，呈现出不同的表型。这些重叠通常伴随着一种以上淀粉样蛋白的共定位，促使人们提出一个问题，即不同淀粉样蛋白之间的直接相互作用是否会产生异型淀粉样物。为了回答这个问题，我们受它们在路易体痴呆和边缘优势型年龄相关 TDP-43 脑病等病理学中的共存启发，研究了 α-突触核蛋白（αS）对 DNA 结合蛋白 TDP-43 聚集的影响。我们之前的研究表明，αS 和 TDP-43 的类朊病毒 C 端结构域（PrLD）协同作用，产生有毒的异型聚集物。在这里，我们扩展了这些研究，以研究αS 是否诱导 PrLD 聚集物的结构和功能不同的多型物。使用两种不同化学计量比例生成的 αS-PrLD 异型聚集物，我们表明αS 可以影响 PrLD 纤维形式。PrLD 纤维表现出独特的残基水平特征，由固态 NMR、染料结合能力、蛋白酶 K（PK）稳定性和 SDS 变性的热稳定性确定。此外，通过金纳米颗粒标记和透射电子显微镜，我们表明在相同的纤维中存在αS 和 PrLD 蛋白，证实了异型淀粉样纤维的存在。我们还观察到αS 和 PrLD 在神经母细胞瘤细胞的细胞质中共定位，并表明异型 PrLD 纤维选择性地诱导原代神经元的突触功能障碍。这些发现确立了异型淀粉样物的存在，并为观察到的突触核蛋白病和 TDP-43 蛋白病之间的重叠提供了分子基础。
