Wu Xinmin, Mao Hui, Liu Jiao, Xu Jian, Cao Jianhua, Gu Xingxing, Cui Gang
Department of Neurology, Affiliated Hospital of Nantong University, Nantong, Jiangsu Province 226001, People's Republic of China.
Int J Clin Exp Pathol. 2013 Jun 15;6(7):1282-93. Print 2013.
Activation of specific signaling pathways in response to mechanical trauma causes delayed neuronal apoptosis; GSK-3β/β-catenin signaling plays a critical role in the apoptosis of neurons in CNS diseases, SGK was discovered as a regulator of GSK-3β/β-catenin pathway, The goal of this study was to determine if the mechanism of cell death or survival mediated by the SGK/GSK-3β/β-catenin pathway is involved in a rat model of TBI.
Here, an acute traumatic brain injury model was applied to investigate the expression change and possible roles of SGK, Expression of SGK, and total-GSK-3β, phospho-GSK3β on ser-9, beta-catenin, and caspase-3 were examined by immunohistochemistry and Western blot analysis. Double immunofluorescent staining was used to observe the SGK localizations. Si-RNA was performed to identify whether SGK regulates neuron apoptosis via GSK-3β/β-catenin pathway, ultimately inhibit caspase-3 activation.
Temporally, SGK expression showed an increase pattern after TBI and reached a peak at day 3. Spatially, SGK was widely expressed in the neuron, rarely in astrocytes and oligodendrocytes; in addition, the expression patterns of active caspase-3 and phospho-GSK3β were parallel with that of SGK, at the same time, the expression of β-catenin shows similarity with SGK. In vitro, to further investigate the function of SGK, a neuronal cell line PC12 was employed to establish an apoptosis model. We analyzed the association of SGK with apoptosis on PC12 cells by western blot, immunofluorescent labeling and siRNA.
the results implied that SGK plays an important role in neuron apoptosis via the regulation of GSK3β/β-catenin signaling pathway; ultimately inhibit caspase-3 activation. Taken together, we inferred traumatic brain injury induced an upregulation of SGK in the central nervous system, which show a protective role in neuron apoptosis.
响应机械性创伤而激活特定信号通路会导致延迟性神经元凋亡；糖原合成酶激酶-3β/β-连环蛋白信号通路在中枢神经系统疾病中神经元凋亡过程中起关键作用，血清和糖皮质激素诱导激酶（SGK）被发现是糖原合成酶激酶-3β/β-连环蛋白信号通路的调节因子，本研究的目的是确定SGK/糖原合成酶激酶-3β/β-连环蛋白信号通路介导的细胞死亡或存活机制是否参与创伤性脑损伤大鼠模型。
在此，应用急性创伤性脑损伤模型来研究SGK的表达变化及可能作用，通过免疫组织化学和蛋白质印迹分析检测SGK、总糖原合成酶激酶-3β、丝氨酸9位点磷酸化糖原合成酶激酶3β、β-连环蛋白和半胱天冬酶-3的表达。采用双重免疫荧光染色观察SGK的定位。进行小干扰RNA（Si-RNA）实验以确定SGK是否通过糖原合成酶激酶-3β/β-连环蛋白信号通路调节神经元凋亡，最终抑制半胱天冬酶-3激活。
在时间上，创伤性脑损伤后SGK表达呈增加模式，并在第3天达到峰值。在空间上，SGK在神经元中广泛表达，在星形胶质细胞和少突胶质细胞中很少表达；此外，活性半胱天冬酶-3和磷酸化糖原合成酶激酶3β的表达模式与SGK平行，同时，β-连环蛋白的表达与SGK相似。在体外，为进一步研究SGK的功能，采用神经元细胞系PC12建立凋亡模型。我们通过蛋白质印迹、免疫荧光标记和小干扰RNA分析了SGK与PC12细胞凋亡的关联。
结果表明SGK通过调节糖原合成酶激酶3β/β-连环蛋白信号通路在神经元凋亡中起重要作用；最终抑制半胱天冬酶-3激活。综上所述，我们推断创伤性脑损伤诱导中枢神经系统中SGK上调，这在神经元凋亡中发挥保护作用。
