骨髓间充质干细胞向神经细胞分化中Tau蛋白的表达

EXPRESSIONS OF TAU PROTEIN DURING THE DIFFERENTIATION PROCESS OF MESENCHYMAL STEM CELLS INTO NEURAL CELLS

目的:观察骨髓间充质干细胞(MSCs)分化为神经细胞过程中,神经元微管相关蛋白Tau及其磷酸化位点pSer202的表达和含量的差异,探讨Tau蛋白在此过程中的作用。方法:使用EGF和bFGF联合诱导第4、第8和第12代的MSCs向神经细胞分化;14d后,免疫细胞化学法检测Tau蛋白和pSer202的表达;ELISA法分析各代细胞Tau蛋白含量。结果:第4、第8和第12代未诱导组Tau蛋白阳性细胞均<6%;诱导14d后,各代MSCs在形态上均分化为类似神经元样细胞,Tau蛋白阳性细胞率较未诱导组显著升高(P<0.05),但各代之间无显著性,而pSer202在各代MSCs未诱导组和诱导组中均未见表达。ELISA法检测发现Tau蛋白含量在诱导过程中呈上升趋势,14d时各代细胞分化后的Tau蛋白升高程度无显著性差异。结论:MSCs向神经细胞分化过程中Tau蛋白表达量增加且可能尚未发生磷酸化,将有助于神经细胞的正常分化和突触形成。

To observe expressions and changes of Tau protein, pSer202 and Tau protein＇s contents during the differentiation process of bone-marrow mesenchymal stem cells （MSCs） into neural cells, and discuss Tau＇s effects on it. Methods： EGF and bFGF were combined for the induction of 4th, 8th, and 12th-MSCs into neural cells. Expressions of Tan protein and pSer202 were tested by immunocytochemistry. ELISA assay was applied for testing Tau protein＇s contents during differentiation process. Results： Positive rates of Tau protein in uninduced MSCs of 4th, 8th, and 12th-MSCs were under 〈6% ; After 14-day induction, the celluar morphologic characteristics in different passages were very similar to neurons, positive rates of Tau protein had no significant differences between passages （P〉0.05）, but had differences with their uninduced groups（ P 〈 0.05）. There hadn＇t had expression of pSer202 in uniduced and induced groups of passages. ELISA assay indicated that there was an upward tendency in Tau protein＇s contents during the 14-day induction process, those in the 14th day had no significant differences between passages too （P 〉 0.05）. Conclusion： The increase in Tau protein＇s expressions and its non-phosphorylated state may make for MSCs differentiating into normal neural cells and formation of neuronal processes.