Center for Neurodegenerative and Neuroimmunologic Diseases, Department of Neurology, Rutgers-Robert Wood Johnson Medical School, Piscataway, New Jersey, USA; and.
Department of Neurosciences, School of Medicine, University of California-San Diego, La Jolla, California, USA.
FASEB J. 2014 Oct;28(10):4280-91. doi: 10.1096/fj.14-251413. Epub 2014 Jun 26.
α-Synuclein is a key pathogenic protein that aggregates in hallmark lesions in Parkinson's disease and other α-synucleinopathies. Prior in vitro studies demonstrated that it is a substrate for cross-linking by transglutaminase 2 (TG2) into higher-order species. Here we investigated whether this increased aggregation occurs in vivo and whether TG2 exacerbates α-synuclein toxicity in Mus musculus and Saccharomyces cerevisiae. Compared with α-synuclein transgenic (Syn(Tg)) mice, animals double transgenic for human α-synuclein and TG2 (TG2(Tg)/Syn(Tg)) manifested greater high-molecular-weight insoluble species of α-synuclein in brain lysates and developed α-synuclein aggregates in the synaptic vesicle fraction. In addition, larger proteinase K-resistant aggregates developed, along with increased thioflavin-S-positive amyloid fibrils. This correlated with an exaggerated neuroinflammatory response, as seen with more astrocytes and microglia. Further neuronal damage was suggested by greater morphological disruption of nerve fibers and a trend toward decreased c-Fos immunoreactive neurons. Finally, the performance of TG2(Tg)/Syn(Tg) animals on motor behavioral tasks was worse relative to Syn(Tg) mice. Greater toxicity of α-synuclein was also demonstrated in yeast cells coexpressing TG2. Our findings demonstrate that TG2 promotes the aggregation of α-synuclein in vivo and that this is associated with aggravated toxicity of α-synuclein and its downstream neuropathologic consequences.
α-突触核蛋白是一种关键的致病蛋白，它在帕金森病和其他 α-突触核蛋白病的标志性病变中聚集。先前的体外研究表明，它是转谷氨酰胺酶 2（TG2）交联形成高级物种的底物。在这里，我们研究了这种增加的聚集是否发生在体内，以及 TG2 是否会加剧 Mus musculus 和 Saccharomyces cerevisiae 中的 α-突触核蛋白毒性。与 α-突触核蛋白转基因（Syn（Tg））小鼠相比，人类 α-突触核蛋白和 TG2 的双转基因动物（TG2（Tg）/Syn（Tg））在脑裂解物中表现出更高分子量的不溶性 α-突触核蛋白，并且在突触小泡部分中形成 α-突触核蛋白聚集体。此外，还形成了更大的蛋白酶 K 抗性聚集体，以及更多的硫黄素-S 阳性淀粉样纤维。这与神经炎症反应的加剧有关，表现为更多的星形胶质细胞和小胶质细胞。进一步的神经元损伤表现为神经纤维的形态破坏更大，c-Fos 免疫反应性神经元减少的趋势。最后，与 Syn（Tg）小鼠相比，TG2（Tg）/Syn（Tg）动物在运动行为任务上的表现更差。在共表达 TG2 的酵母细胞中也证明了 α-突触核蛋白的毒性更大。我们的研究结果表明，TG2 促进了体内 α-突触核蛋白的聚集，这与 α-突触核蛋白毒性的加剧及其下游神经病理学后果有关。
