Banner Sun Health Research Institute, Sun City, AZ 85351, USA.
Exp Neurol. 2013 Feb;240:190-204. doi: 10.1016/j.expneurol.2012.11.020. Epub 2012 Nov 28.
Modifications of α-synuclein resulting in changes in its conformation are considered to be key pathological events for Lewy body diseases (LBD), which include Parkinson's disease (PD) and dementia with Lewy bodies (DLB). We have previously described a histopathological Unified Staging System for LBD that classifies the spread of α-synuclein phosphorylated at serine 129 (pS129-α-synuclein) from olfactory bulb to brainstem or limbic regions, and finally neocortex. Lewy bodies and Lewy neurites are highly enriched in pS129-α-synuclein. Increased formation of pS129-α-synuclein changes its solubility properties enhancing its tendency to aggregate and disrupt normal function. As in vitro and animal studies have shown that inhibiting formation of pS129-α-synuclein can prevent toxic consequences, this has become one of the therapeutic targets for LBD. However, detailed biochemical descriptions of the changes in pS129-α-synuclein properties in diseased human brains are needed to further our understanding of how these might contribute to molecular pathogenesis. In this study, we used 130 separate brain samples from cingulate cortex (limbic cortex) and 131 from temporal cortex (neocortex) that had been staged according to our Unified Staging System to examine progressive changes in properties of pS129-α-synuclein with the formation of progressively more severe histological Lewy-type pathology. The brain samples from these staged cases had been separated into cytosol-enriched, membrane-enriched (detergent soluble) and insoluble (ureas/SDS soluble) fractions. We also characterized the nature and appearance of higher molecular weight forms of pS129-α-synuclein. The major species was the 16 kD monomeric form; this accumulated with increasing stage with a large increase in Stage IV samples. By comparing two brain regions, we showed higher accumulation of insoluble pS129-α-synuclein in cingulate cortex, where histological deposits occur first, than in temporal cortex in samples with advanced (stage IV) LB pathology.
导致α-突触核蛋白构象改变的修饰被认为是路易体病（LBD）的关键病理事件，包括帕金森病（PD）和路易体痴呆（DLB）。我们之前描述了一种 LBD 的组织病理学统一分期系统，该系统将磷酸化丝氨酸 129 位的α-突触核蛋白（pS129-α-突触核蛋白）从嗅球到脑干或边缘区域，最后到新皮质的扩散进行分类。路易体和路易神经突富含 pS129-α-突触核蛋白。pS129-α-突触核蛋白形成增加会改变其可溶性，增强其聚集倾向并破坏正常功能。由于体外和动物研究表明抑制 pS129-α-突触核蛋白的形成可以防止毒性后果，因此这已成为 LBD 的治疗靶点之一。然而，需要对患病人大脑中 pS129-α-突触核蛋白特性的变化进行详细的生化描述，以进一步了解这些变化如何导致分子发病机制。在这项研究中，我们使用了根据我们的统一分期系统分期的 130 个来自扣带回皮质（边缘皮质）和 131 个来自颞叶皮质（新皮质）的大脑样本，以检查随着越来越严重的组织学路易型病理学的形成，pS129-α-突触核蛋白特性的进行性变化。来自这些分期病例的大脑样本被分离成富含细胞质、富含膜（去污剂可溶性）和不溶性（尿素/SDS 可溶性）部分。我们还对 pS129-α-突触核蛋白的高分子量形式的性质和外观进行了表征。主要物种是 16 kD 单体形式；随着阶段的增加而积累，在第四阶段样品中大量增加。通过比较两个大脑区域，我们发现在组织学沉积物首先发生的扣带皮质中，不溶性 pS129-α-突触核蛋白的积累高于颞叶皮质中具有高级（第四阶段）LB 病理学的样本。
