Xu Ting, Fan Xinjuan, Tan Yuanyuan, Yue Ying, Chen Weijie, Gu Xingxing
The Center Laboratory of Huai'an First People's Hospital Nanjing Medical University, Huai'an 223300, China.
Affiliated Hospital of Nantong University, Nantong 226001, China.
Int J Mol Sci. 2014 Feb 21;15(2):3299-318. doi: 10.3390/ijms15023299.
Prohibitin2 (PHB2) is a ubiquitous, evolutionarily strongly conserved protein. It is one of the components of the prohibitin complex, which comprises two highly homologous subunits, PHB1 and PHB2. PHB2 is present in various cellular compartments including the nucleus and mitochondria. Recent studies have identified PHB2 as a multifunctional protein that controls cell proliferation, apoptosis, cristae morphogenesis and the functional integrity of mitochondria. However its distribution and function in the central nervous system (CNS) are not well understood. In this study, we examined PHB2 expression and cellular localization in rats after acute traumatic brain injury (TBI). Western Blot analysis showed PHB2 level was significantly enhanced at five days after injury compared to control, and then declined during the following days. The protein expression of PHB2 was further analyzed by immunohistochemistry. In comparison to contralateral cerebral cortex, we observed a highly significant accumulation of PHB2 at the ipsilateral brain. Immunofluorescence double-labeling showed that PHB2 was co-expressed with NeuN, GFAP. Besides, PHB2 also colocalized with activated caspase-3 and PCNA. To further investigate the function of PHB2, primary cultured astrocytes and the neuronal cell line PC12 were employed to establish a proliferation model and an apoptosis model, respectively, to simulate the cell activity after TBI to a certain degree. Knocking down PHB2 by siRNA partly increased the apoptosis level of PC12 stimulated by H2O2. While the PHB2 was interrupted by siRNA, the proliferation level of primary cultured astrocytes was inhibited notably than that in the control group. Together with our data, we hypothesized that PHB2 might play an important role in CNS pathophysiology after TBI.
抑制素2（PHB2）是一种普遍存在且在进化上高度保守的蛋白质。它是抑制素复合体的组成成分之一，该复合体由两个高度同源的亚基PHB1和PHB2组成。PHB2存在于包括细胞核和线粒体在内的各种细胞区室中。最近的研究已将PHB2鉴定为一种多功能蛋白质，其可控制细胞增殖、凋亡、嵴形态发生以及线粒体的功能完整性。然而，其在中枢神经系统（CNS）中的分布和功能尚未完全明确。在本研究中，我们检测了急性创伤性脑损伤（TBI）后大鼠体内PHB2的表达及细胞定位。蛋白质印迹分析显示，与对照组相比，损伤后5天PHB2水平显著升高，随后在接下来的几天中下降。通过免疫组织化学进一步分析了PHB2的蛋白表达。与对侧大脑皮质相比，我们观察到同侧脑内PHB2有高度显著的积聚。免疫荧光双标记显示PHB2与NeuN、GFAP共表达。此外，PHB2还与活化的半胱天冬酶-3和增殖细胞核抗原（PCNA）共定位。为进一步研究PHB2的功能，分别采用原代培养的星形胶质细胞和神经元细胞系PC12建立增殖模型和凋亡模型，以在一定程度上模拟TBI后的细胞活性。用小干扰RNA（siRNA）敲低PHB2可部分增加H2O2刺激的PC12细胞的凋亡水平。当PHB2被siRNA阻断时，原代培养的星形胶质细胞的增殖水平比对照组显著受到抑制。综合我们的数据，我们推测PHB2可能在TBI后的CNS病理生理过程中起重要作用。
