中文摘要：

目的观察MANF是否可以抑制冈田酸诱导的N2a细胞中tau蛋白的过度磷酸化，以了解MANF神经保护作用的机制。方法采用体外培养小鼠神经母瘤细胞株N2a，以冈田酸（okadaic aicd, OA）作为诱导剂诱导N2a细胞中tau蛋白过度磷酸化，在加入重组人MANF蛋白干预或转染MANF过表达质粒及siRNA后，用MTT法检测细胞增殖活性的变化，并用AT8抗体检测tau蛋白ser202/Thr205位点的磷酸化水平变化。结果N2a细胞在加入重组人MANF蛋白预处理4 h后加入OA诱导24 h后，经Western blot和MTT法检测发现，重组人MANF蛋白能明显抑制N2a细胞中tau蛋白的过度磷酸化，并可促进N2a细胞的增殖活性；在转染MANF过表达质粒后，N2a细胞中 OA诱导的过度磷酸化tau蛋白减少，且细胞活性增加；与此相反，转染siRNA下调内源性的MANF的表达则能促进N2a细胞中的tau蛋白过度磷酸化，并抑制细胞活性。结论MANF可以抑制神经细胞中tau蛋白过度磷酸化，这可能是其发挥神经保护作用的原因之一。

英文摘要：

Aim To investigate the suppressive effect of MANF on okadaic acid （OA）-induced tau hyper- phosphorylation in N2a cells. Methods Mouse neuroblastoma N2a cells were cultured, and okadaic acid （OA） was used to induce tau hyperphosphorylation in N2a cells. The cells were treated with recombinant human MANF protein before exposure of OA. Meanwhile, MANF cDNA or siRNA was transfected to the cells to confirm the protective effect of MANF. The phosphorylated tau was detected by using AT-8 anti- body, which recognized Ser202/Thr205 phosphorylation of tau. The cell viability was determined by MTT assay. Results Pretreatment with recombinant human MANF for 4 h before OA exposure for 24 h, the viabil- ity of N2a was increased and the cellular level of hyperphosphorylated tau was decreased. Similarly, MANF cDNA transfection inhibited OA-induced tau hyperphosphorylation and cell impairment in N2a cells, whereas MANF siRNA transfeetion had an opposite effect. Conclusion MANF can inhibit tau hyperphosphorylation in N2a cells, which may be associated with its protective effects on neuronal cells.