Song Qing, Gou Wen-Li, Zhang Rong
Department of Obstetrics and Gynecology, the First Affiliated Hospital, Xian Jiaotong University, 277 Yanta West Road, Xi'an, Shaanxi 710061, China.
Department of Obstetrics and Gynecology, the First Affiliated Hospital, Xian Jiaotong University, 277 Yanta West Road, Xi'an, Shaanxi 710061, China.
Neurochem Int. 2016 Mar;94:82-9. doi: 10.1016/j.neuint.2016.02.010. Epub 2016 Mar 3.
Endoplasmic reticulum (ER) stress is linked to several neurological disorders, and neuronal injury cascades initiated by excessive ER stress are mediated, in part, via mitochondrial dysfunction. In the present study, we identified FAM3A as an important regulator of ER stress-induced cell death in neuronal HT22 cells. The ER stress inductor tunicamycin (TM) significantly decreased the expression of FAM3A at both mRNA and protein levels, which was shown to be dependent on the induction of reactive oxygen species (ROS). Overexpression of FAM3A attenuated TM-induced apoptosis and activation of ER stress factors, but had no effect on ER calcium metabolism in HT22 cells. We also found decreased mitochondrial ROS generation, inhibited cytochrome c release and preserved mitochondrial membrane potential (MMP) in FAM3A overexpressed cells. In addition, the experiments using isolated mitochondria showed that overexpression of FAM3A attenuated mitochondrial swelling and loss of mitochondrial Ca(2+) buffering capacity after TM exposure. By using specific targeted small interfering RNA (siRNA) to knockdown the expression of the C/EBP homologous protein (CHOP), we found that FAM3A-induced protection and inhibition of ER stress was mediated by inverting TM-induced decrease of Wnt through the CHOP pathway. Our study demonstrates a pivotal role of FAM3A in protecting against TM-induced cytotoxicity via regulating CHOP-Wnt pathway, and suggests the therapeutic values of FAM3A overexpression against ER stress-associated neuronal injury.
内质网（ER）应激与多种神经疾病相关，由过度内质网应激引发的神经元损伤级联反应部分是通过线粒体功能障碍介导的。在本研究中，我们确定FAM3A是神经元HT22细胞中内质网应激诱导的细胞死亡的重要调节因子。内质网应激诱导剂衣霉素（TM）在mRNA和蛋白质水平上均显著降低FAM3A的表达，这表明其依赖于活性氧（ROS）的诱导。FAM3A的过表达减弱了TM诱导的细胞凋亡和内质网应激因子的激活，但对HT22细胞中的内质网钙代谢没有影响。我们还发现，在FAM3A过表达的细胞中，线粒体ROS生成减少，细胞色素c释放受到抑制，线粒体膜电位（MMP）得以维持。此外，使用分离线粒体的实验表明，FAM3A的过表达减弱了TM暴露后线粒体肿胀和线粒体Ca(2+)缓冲能力的丧失。通过使用特异性靶向小干扰RNA（siRNA）敲低C/EBP同源蛋白（CHOP）的表达，我们发现FAM3A诱导的保护作用和内质网应激抑制是通过CHOP途径逆转TM诱导的Wnt减少来介导的。我们的研究证明了FAM3A在通过调节CHOP-Wnt途径预防TM诱导的细胞毒性方面的关键作用，并提示FAM3A过表达对内质网应激相关神经元损伤的治疗价值。
