Department of Neurosurgery, Xijing Hospital of the Fourth Military Medical University, No. 127 West Changle Road, Xi'an, 710032, Shaanxi Province, People's Republic of China.
J Mol Neurosci. 2013 Nov;51(3):911-8. doi: 10.1007/s12031-013-0099-0. Epub 2013 Aug 27.
Hyperphosphorylated tau protein is the main component of neurofibrillary tangles found in Alzheimer's disease and Parkinson's disease (PD). Mutations in DJ-1 have been identified as the causative gene for Parkinson's disease 7 (PARK7)-linked PD. DJ-1L166P and DJ-1D149A, two types of DJ-1 mutations, are most commonly studied as the loss-of-function mutations responsible for early-onset familial PD. Whether mutations in DJ-1 result in tauopathy is as yet unknown. In this study, we found that the L166P and D149A mutant isoforms of DJ-1 associated with familial PD cause tau phosphorylation at Ser202, Ser262, and PHF1 (396/404) sites in neuroblastoma 2a cells. Glycogen synthase kinase (GSK)-3β phosphorylation at serine 9 (Ser9) decreases around 50 % in DJ-1L166P- or DJ-1D149A-transfected cells, while there is no change in total levels of GSK-3β. Our results also indicate that overexpression of DJ-1L166P or DJ-1D149A leads to a significant decrease in the level of phosphorylation of Akt at Thr308, which plays a critical role in phosphorylating GSK-3β at Ser9 and inhibiting its kinase activity. Importantly, insulin, the activator for Akt, effectively attenuates the reduced phosphorylation level of GSK-3β at Ser9 induced by DJ-1L166P. Neither the expression of cyclin-dependent kinase 5 nor the level of PP2A activity was found to have changed, suggesting that the familial PD-associated DJ-1L166P and DJ-1D149A mutations increase tau phosphorylation by increasing the activity of GSK-3β. Finally, we found that administration of lithium chloride, a well-known GSK-3β inhibitor, resulted in decreased levels of phosphorylated tau in DJ-1L166P-transfected cells.
过度磷酸化的 tau 蛋白是阿尔茨海默病和帕金森病（PD）中神经原纤维缠结的主要成分。DJ-1 中的突变已被确定为帕金森病 7（PARK7）相关 PD 的致病基因。DJ-1L166P 和 DJ-1D149A 是两种 DJ-1 突变类型，作为导致早发性家族性 PD 的失活突变最常被研究。DJ-1 中的突变是否导致 tau 病尚不清楚。在这项研究中，我们发现与家族性 PD 相关的 DJ-1 的 L166P 和 D149A 突变同工型在神经母细胞瘤 2a 细胞中导致 tau 在 Ser202、Ser262 和 PHF1（396/404）位点磷酸化。DJ-1L166P 或 DJ-1D149A 转染细胞中糖原合酶激酶（GSK）-3β 丝氨酸 9（Ser9）磷酸化减少约 50%，而 GSK-3β 的总水平没有变化。我们的结果还表明，DJ-1L166P 或 DJ-1D149A 的过表达导致 Akt 在 Thr308 位点的磷酸化水平显著降低，这在磷酸化 GSK-3β 的 Ser9 并抑制其激酶活性方面起着关键作用。重要的是，胰岛素，Akt 的激活剂，可有效减弱 DJ-1L166P 引起的 GSK-3β Ser9 磷酸化水平降低。未发现细胞周期蛋白依赖性激酶 5 的表达或 PP2A 活性水平发生变化，表明家族性 PD 相关的 DJ-1L166P 和 DJ-1D149A 突变通过增加 GSK-3β 的活性增加 tau 磷酸化。最后，我们发现氯化锂（一种众所周知的 GSK-3β 抑制剂）的给药可导致 DJ-1L166P 转染细胞中磷酸化 tau 水平降低。
