Low molar excess of 4-oxo-2-nonenal and 4-hydroxy-2-nonenal promote oligomerization of alpha-synuclein through different pathways
Low molar excess of 4-oxo-2-nonenal and 4-hydroxy-2-nonenal promote oligomerization of alpha-synuclein through different pathways
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DOI：
10.1016/j.freeradbiomed.2017.07.004
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发表时间：
2017-09-01
影响因子：
7.4
通讯作者：
Bergstrom, Joakim
中科院分区：
文献类型：
--
作者：
Almandoz-Gil, Leire;Welander, Hedvig;Bergstrom, Joakim
聚集的α-突触核蛋白是路易体的主要成分，路易体是在帕金森病和路易体痴呆的大脑中发现的神经元内包涵体。大量证据表明氧化应激与这些疾病的发病机制有关。例如，脂质过氧化终产物4-氧代-2-壬烯醛（ONE）或4-羟基-2-壬烯醛（HNE）的大量过量（30：1，醛：蛋白质）可诱导α-突触核蛋白寡聚体形成。该研究的目的是调查这些反应性醛对α-突触核蛋白的影响，在较低的摩尔过量（3：1）在生理（7.4）和酸性（5.4）pH值。如尺寸排阻色谱法所观察到的，ONE迅速诱导形成α-突触核蛋白低聚物在两个pH值，但效果不太明显的酸性条件下。相比之下，在生理pH下用低过量HNE处理仅形成小比例的α-突触核蛋白寡聚体，并且在酸性条件下根本没有寡聚体。随着孵育时间的延长（长达96小时），ONE和HNE在生理pH下寡聚化更多的α-突触核蛋白。如通过蛋白质印迹所确定的，与HNE诱导的寡聚体相比，ONE-寡聚体更SDS稳定并且交联程度更高。然而，如它们对蛋白酶K处理的更大敏感性所示，ONE-寡聚物表现出比HNE-寡聚物更不紧凑的结构。如质谱所示，ONE修饰了大多数Lys残基，而HNE主要修饰了His 50残基和较少的Lys残基，尽管程度高于ONE。总之，我们的数据表明，醛ONE和HNE可以修饰α-突触核蛋白并诱导寡聚化，即使在低摩尔过量下，但在生理pH下程度更高，并且似乎通过不同的途径。
Aggregated alpha-synuclein is the main component of Lewy bodies, intraneuronal inclusions found in brains with Parkinson's disease and dementia with Lewy bodies. A body of evidence implicates oxidative stress in the pathogenesis of these diseases. For example, a large excess (30: 1, aldehyde: protein) of the lipid peroxidation end products 4-oxo-2-nonenal (ONE) or 4-hydroxy-2-nonenal (HNE) can induce alpha-synuclein oligomer formation. The objective of the study was to investigate the effect of these reactive aldehydes on alpha-synuclein at a lower molar excess (3: 1) at both physiological (7.4) and acidic (5.4) pH. As observed by size-exclusion chromatography, ONE rapidly induced the formation of alpha-synuclein oligomers at both pH values, but the effect was less pronounced under the acidic condition. In contrast, only a small proportion of alpha-synuclein oligomers were formed with low excess HNE-treatment at physiological pH and no oligomers at all under the acidic condition. With prolonged incubation times (up to 96 h), more alpha-synuclein was oligomerized at physiological pH for both ONE and HNE. As determined by Western blot, ONE-oligomers were more SDS-stable and to a higher-degree cross-linked as compared to the HNE-induced oligomers. However, as shown by their greater sensitivity to proteinase K treatment, ONE-oligomers, exhibited a less compact structure than HNE-oligomers. As indicated by mass spectrometry, ONE modified most Lys residues, whereas HNE primarily modified the His50 residue and fewer Lys residues, albeit to a higher degree than ONE. Taken together, our data show that the aldehydes ONE and HNE can modify alpha-synuclein and induce oligomerization, even at low molar excess, but to a higher degree at physiological pH and seemingly through different pathways.