γ-分泌酶抑制剂对神经干细胞增殖和分化的影响

目的 探讨γ-分泌酶抑制剂3,5-二氟苯乙酰-L-丙氨酰-S苯基甘氨酸t-丁酯(DAPT)与神经干细胞增殖、分化的关系.方法 分离和体外培养大鼠脑神经干细胞(NSC),采用γ-分泌酶抑制剂DAPT处理后,细胞计数和CCK8检测法观察NSC增殖能力的变化;特异性荧光免疫染色检测NSC诱导定向分化能力的变化;逆转录聚合酶链反应(RT-PCR)检测Notch信号途径节点分子基因RBP-Jk和Hes1的表达.结果 DAPT能够明显抑制NSC的增殖能力;与对照组相比,NSC诱导分化为神经元和少突胶质细胞的比例分别由(3.7±1.0)%和(4.8±1.2)%上升为(13.8±1.2)%和(14.8±1.6)%,而分化成星形胶质细胞的比例由(82.8±3.7)%下降为(63.4 ±1.2)%;DAPT能下调NSC的RBP-Jk和Hes1 mRNA的表达.结论 γ-分泌酶抑制剂DAPT能抑制大鼠脑NSC的增殖,改变NSC定向分化的能力,这些作用可能是通过抑制γ-分泌酶而下调Notch信号所致.

Effects of gamma-secretase inhibitor N-(3, 5-difluorophenacetyl-L-alanyl)-S-phenylglycine t-butyl ester on proliferation and differentiation of neural stem cells

OBJECTIVE: To investigate the role of N-N-(3,5-Difluorophenacetyl-L-alanyl)-S-phenylglycine t-butyl ester (DAPT), a gamma-secretases inhibitor, on the proliferation and differentiation of neural stem cells (NSCs). METHODS: NSCs were isolated from Sprague-Dawley rat brain, cultured, and treated with DAPT for 6 weeks. Cell counting was conducted every 24 h. CCK8 assay was used to draw the growth curve. Immunofluoresence staining was performed to observe the proportions of beta-tubulin III positive cells (neurons), glial fibrillary acidic protein (GFAP) positive cells (astrocytes), and 2',3'-cyclic nucleotide3' phosphohydrolase (CNPase) positive cells (oligodentrocytes). RT-PCR was employed to assay the mRNA expression of RBP-Jk and Hes1 genes, downstream genes of the Notch pathway. RESULTS: Cell counting and CCK-8 assay showed that DAPT reduced the rate of NSC proliferation. Addition of DAPT altered NSC differentiation in vitro, percentage of The proportions neurons of the DAPT group was (13.84 +/- 1.22)%, significantly higher than that of the control group (3.7 +/- 1.04)% , P <0.01], the proportion of the oligodendrocytes of the DAPT group was (14.75 +/- 1.58)%, significantly higher than that pf the control group (4.8 +/- 1.22)%, P < 0.01]. However, the proportion of astrocytes of the DAPT group was (63.41 +/- 1.20)%, significantly lower than that of the control group (82.84 +/- 3.68)%, P <0.01]. The expression levels of RBP-Jk and Hes1 mRNA (RBP-Jk/GAPDH and Hesl/GAPDH) in the NSC treated with DAPT were 0.52 +/- 0.13 and 0.66 +/- 0.18 espectively, both significantly lower than those of the control group (0.28 +/- 0.06 and 0.16 +/- 0.08 respectively, both P <0.05). CONCLUSION: DAPT inhibits the NSC proliferation and alters the NSC committed differentiation. These effects are mediated via Notch signaling down regulation as a result of the inhibition of gamma-secretase.