Involvement of PI3K/Akt pathway in the neuroprotective effect of sonic hedgehog on cortical neurons under oxidative stress
Involvement of PI3K/Akt pathway in the neuroprotective effect of sonic hedgehog on cortical neurons under oxidative stress
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PI3K/Akt通路参与Sonic Hedgehog对氧化应激下皮质神经元的神经保护作用
DOI：
10.1007/s11596-012-1047-x
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发表时间：
2012-12-01
影响因子：
--
通讯作者：
Hu, Bo
中科院分区：
文献类型：
--
作者：
Dai, Ruolian;Xia, Yuanpeng;Hu, Bo
Sonic hedgehog(SHH)信号通路在神经发生和脑损伤修复中起着关键作用。我们以前的工作证明SHH信号通路参与了大脑皮层神经元对氧化应激的神经保护。本研究旨在进一步探讨其潜在的机制。皮质神经元取自1日龄SD新生大鼠。用过氧化氢(H_2O_2,100μ/L)处理神经元24 h，诱导氧化应激。外源性促性腺激素释放激素(3μg/mL)激活促肾上腺皮质激素释放激素通路，环多巴胺(20μ/L)阻断促肾上腺皮质激素释放通路。用LY294002(20Mol/L)在H_2O_2处理前30min对神经元进行预处理，选择性地抑制磷脂酰肌醇3-激酶(PI3K)/μ通路。四甲基偶氮唑盐比色法检测细胞存活率，流式细胞仪检测细胞凋亡率。免疫印迹法检测神经元p38、p-p38、ERK、p-ERK、Akt、p-Akt、Bcl2、Bax的表达。结果表明，与H_2O_2处理相比，外源SHH可使p-Akt的表达增加20%，p-ERK的表达降低33%。Shh对p38丝裂原活化蛋白激酶(P38 MAPK)通路无明显影响。LY294002阻断PI3K/Akt通路后，细胞存活率下降17%，细胞凋亡率增加2倍。LY294002可上调促凋亡基因Bax的表达12%，下调抗凋亡基因Bcl2的表达54%。综上所述，SHH通路可能激活氧化应激下神经元中的PI3K/Akt通路，抑制ERK通路的激活。PI3K/Akt通路在SHH的神经保护中起关键作用。Shh/PI3K/Bcl2通路可能参与保护神经元免受过氧化氢诱导的细胞凋亡。
The Sonic hedgehog (SHH) signaling pathway plays a pivotal role in neurogenesis and brain damage repair. Our previous work demonstrated that the SHH signaling pathway was involved in the neuroprotection of cortical neurons against oxidative stress. The present study was aimed to further examine the underlying mechanism. The cortical neurons were obtained from one-day old Sprague-Dawley neonate rats. Hydrogen peroxide (H2O2, 100 μmol/L) was used to treat neurons for 24 h to induce oxidative stress. Exogenous SHH (3 μg/mL) was employed to activate the SHH pathway, and cyclopamine (20 μmol/L), a specific SHH signal inhibitor, to block SHH pathway. LY294002 (20 μmol/L) were used to pre-treat the neurons 30 min before H2O2treatment and selectively inhibit the phosphatidylinositol 3-kinase (PI3K)/Akt pathway. The cell viability was measured by MTT and apoptosis rate by flow cytometry analysis. The expression of p38, p-p38, ERK, p-ERK, Akt, p-Akt, Bcl-2, and Bax in neurons was detected by immunoblotting. The results showed that as compared with H2O2treatment, exogenous SHH could increase the expression of p-Akt by 20% and decrease the expression of p-ERK by 33%. SHH exerted no significant effect on p38 mitogen-activated protein kinase (p38 MAPK) pathway. Blockade of PI3K/Akt pathway by LY294002 decreased the cell viability by 17% and increased the cell apoptosis rate by 2-fold. LY294002 treatment could up-regulate the expression of the pro-apoptotic gene Bax by 12% and down-regulate the expression of the anti-apoptotic gene Bcl-2 by 54%. In conclusion, SHH pathway may activate PI3K/Akt pathway and inhibit the activation of the ERK pathway in neurons under oxidative stress. The PI3K/Akt pathway plays a key role in the neuroprotection of SHH. SHH/PI3K/Bcl-2 pathway may be implicated in the protection of neurons against H2O2-induced apoptosis.