抑制磷酸酶和tau过度磷酸化诱导神经细胞凋亡

Inhibition of protein phosphatases induces apoptosis in neuroblastoma cells

目的 探讨磷酸酶活性抑制、tau蛋白异常磷酸化与神经细胞变性死亡的关系。方法 磷酸酶 (PP) 2A/PP 1抑制剂岗田酸 (okadaicacid ,OA) 10nmol/L与成神经细胞瘤细胞 (SH SY5Y)共培养 ,DNA 梯带和末端转移酶标记技术。结果 用 10nmol/LOA与SY5Y细胞共培养 2 4h和 4 8h均可引起DNA 梯带出现 ,此时末端转移酶标记显示阳性细胞数由 2 16%± 0 94 %分别增多至 18 0 5 %±3 5 7% (P <0 0 1)和 2 2 5 2 %± 4 78% (P <0 0 1)。结论 由于上述检测指标均与细胞凋亡有关 ,提示抑制PP 2A和部分抑制PP 1引起tau蛋白异常磷酸化可能通过神经细胞凋亡而引起AD患者神经细胞丢失。

Objective To investigate the relationship between protein phosphatase inhibition, tau hyperphosphorylation and neuronal death seen in Alzheimer disease (AD). Methods Co culture of protein phosphatase inhibitor okadaic acid (OA) and neuroblastoma cells (SH SY5Y), by agarose gel electrophoresis to detect DNA fragmentation, and in situ hybridization by TdT mediated biotin labeled dNTP nick end labeling (TUNEL) to further detect the cell apoptosis. Results Incubation of SY5Y cells with 10 nmol/L OA for 24 or 48 hours led to the appearance of DNA fragmentation and a remarkable increase of positive cells from 2 16%±0 94% to 18 05%±3 57% ( P <0 01) and 22 52%±4 78%( P <0 01) Both are markers of cell apoptosis. Conclusions The data suggest that the hyperphosphorylation of tau caused by deficiency of protein phosphatase(s) may lead to the neuronal loss in AD patients through apoptosis