Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
Neurosci Lett. 2012 Feb 21;510(1):48-52. doi: 10.1016/j.neulet.2011.12.067. Epub 2012 Jan 9.
Presence of cytoplasmic tau aggregates is a hallmark of brains in patients with tauopathies such as Alzheimer's disease. However, the mechanism underlying formation of these insoluble tau aggregates remains elusive. In this study, we investigated the impact of prolonged nitric oxide (NO) exposure on neuronal SH-SY5Y cells overexpressing human tau. Treatment with the NO donor DETA NONOate for up to 48h resulted in an increase in S-nitrosation of cellular proteins, inactivation of proteasome, and impairment of respiration. Western blot analysis of Triton X-soluble fractions of NO-treated cells revealed that persistent NO treatment increased heterogeneity in tau molecule size, as a result of dephosphorylation, and induced the formation of sodium dodecyl sulfate (SDS)-stable oligomeric tau aggregates, stabilized by disulfide bonds. Moreover, further NO treatment induced the formation of SDS-stable insoluble tau mega-aggregates that were composed of dephosphorylated full-length tau molecules and other proteins, and were stabilized through disulfide bonds. Evaluation of the role of these tau aggregates as potential seeds for tau fibrillization and elucidation of their formation mechanism in our model, could lead to better understanding of the pathogenesis of tauopathies.
细胞浆中tau 聚集物的存在是tau 病患者大脑的一个标志，如阿尔茨海默病。然而，这些不溶性 tau 聚集物形成的机制仍不清楚。在这项研究中，我们研究了延长一氧化氮（NO）暴露对过表达人tau 的神经元 SH-SY5Y 细胞的影响。用 NO 供体 DETA NONOate 处理长达 48 小时会导致细胞蛋白的 S-亚硝基化增加、蛋白酶体失活和呼吸受损。对 NO 处理细胞的 Triton X-可溶性部分进行的 Western blot 分析表明，持续的 NO 处理会增加 tau 分子大小的异质性，这是由于去磷酸化引起的，并诱导形成十二烷基硫酸钠（SDS）稳定的寡聚 tau 聚集物，这些聚集物通过二硫键稳定。此外，进一步的 NO 处理诱导 SDS 稳定的不溶性 tau 巨聚集物的形成，这些聚集物由去磷酸化的全长 tau 分子和其他蛋白质组成，并通过二硫键稳定。评估这些 tau 聚集物作为 tau 纤维形成的潜在种子的作用，并阐明它们在我们的模型中的形成机制，可以更好地理解 tau 病的发病机制。
