Chen Xiaomei, Shen Jiabing, Wang Yang, Chen Xiaojing, Yu Shi, Shi Huili, Huo Keke
State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, 220 Handan Rd, Shanghai, 200433, China.
Department of Neurology, Affiliated Hospital of Nantong University, Nantong, Jiangsu Province, China.
Cell Mol Neurobiol. 2015 Apr;35(3):363-376. doi: 10.1007/s10571-014-0132-z. Epub 2014 Oct 30.
The proto-oncogene c-Fos is an important member of the activating protein 1 (AP-1) transcription complex involved in major cellular functions such as transformation, proliferation, differentiation, and apoptosis. The expression of c-Fos is very tightly regulated and responses rapidly and transiently to a plethora of apoptotic stimuli. However, it is still unclear how c-Fos functions on neuronal activities following intracerebral hemorrhage (ICH). In the present studies, we uncovered that the up-regulation of c-Fos is related to neuronal apoptosis following ICH probably via FasL/Fas apoptotic pathway. From the results of Western blot and immunohistochemistry, we obtained that c-Fos is significantly up-regulated surrounding the hematoma following ICH and co-locates with active caspase-3 in the neurons. Besides, electrophoretic mobility shift assay exhibits high AP-1 DNA-binding activities in ICH groups due to the increase of c-Fos expression. In addition, there are concomitant up-regulation of Fas ligand (FasL), which is the target protein of AP-1, Fas, active caspase-8, and active caspase-3 in vivo and in vitro studies. What is more, our in vitro study showed that using c-Fos-specific RNA interference in primary cortical neurons, the expression of FasL and active caspase-3 are suppressed. Thus, our results indicated that c-Fos might exert its pro-apoptotic function on neuronal apoptosis following ICH.
原癌基因c-Fos是激活蛋白1（AP-1）转录复合物的重要成员，参与多种主要细胞功能，如转化、增殖、分化和凋亡。c-Fos的表达受到严格调控，对大量凋亡刺激能迅速产生短暂反应。然而，脑出血（ICH）后c-Fos如何影响神经元活动仍不清楚。在本研究中，我们发现脑出血后c-Fos的上调可能通过FasL/Fas凋亡途径与神经元凋亡有关。通过蛋白质印迹法和免疫组织化学结果，我们发现脑出血后血肿周围c-Fos显著上调，并与神经元中的活性半胱天冬酶-3共定位。此外，由于c-Fos表达增加，电泳迁移率变动分析显示脑出血组具有较高的AP-1 DNA结合活性。另外，体内和体外研究均显示Fas配体（FasL）、AP-1的靶蛋白Fas、活性半胱天冬酶-8和活性半胱天冬酶-3伴随上调。更重要的是，我们的体外研究表明，在原代皮质神经元中使用c-Fos特异性RNA干扰，FasL和活性半胱天冬酶-3的表达受到抑制。因此，我们的结果表明，c-Fos可能在脑出血后的神经元凋亡中发挥促凋亡作用。
