Wei Jialiang, Wu Xiuquan, Luo Peng, Yue Kangyi, Yu Yang, Pu Jingnan, Zhang Lei, Dai Shuhui, Han Donghui, Fei Zhou
Department of Neurosurgery, Xijing Hospital, Fourth Military Medical University, Xi'an, China.
Department of Health Services, Fourth Military Medical University, Xi'an, China.
Front Cell Neurosci. 2019 Mar 15;13:101. doi: 10.3389/fncel.2019.00101. eCollection 2019.
Homer1a is the short form of a scaffold protein that plays a protective role in many forms of stress. However, the role of Homer1a in cerebral ischemia/reperfusion (I/R) injury and its potential mechanism is still unknown. In this study, we found that Homer1a was upregulated by oxygen and glucose deprivation (OGD) and that overexpression of Homer1a alleviated OGD-induced lactate dehydrogenase (LDH) release and cell death in cultured cortical neurons. After OGD treatment, the overexpression of Homer1a preserved mitochondrial function, as evidenced by less cytochrome c release, less reactive oxygen species (ROS) production, less ATP and mitochondrial membrane potential (MMP) loss, less caspase-9 activation, and inhibition of endoplasmic reticulum (ER) stress confirmed by the decreased expression of phosphate-PKR-like ER Kinase (p-PERK)/PERK and phosphate- inositol-requiring enzyme 1 (p-IRE1)/IRE1 and immunofluorescence (IF) staining. In addition, mitochondrial protection of Homer1a was blocked by the ER stress activator Tunicamycin (TM) with a re-escalated ROS level, increasing ATP and MMP loss. Furthermore, Homer1a overexpression-induced mitochondrial stress attenuation was significantly reversed by activating the PERK pathway with TM and p-IRE1 inhibitor 3,5-dibromosalicylaldehyde (DBSA), as evidenced by increased cytochrome c release, increased ATP loss and a higher ROS level. However, activating the IRE1 pathway with TM and p-PERK inhibitor GSK2656157 showed little change in cytochrome c release and exhibited a moderate upgrade of ATP loss and ROS production in neurons. In summary, these findings demonstrated that Homer1a protects against OGD-induced injury by preserving mitochondrial function through inhibiting the PERK pathway. Our finding may reveal a promising target of protecting neurons from cerebral I/R injury.
荷马1a（Homer1a）是一种支架蛋白的短形式，在多种应激形式中发挥保护作用。然而，荷马1a在脑缺血/再灌注（I/R）损伤中的作用及其潜在机制仍不清楚。在本研究中，我们发现氧气和葡萄糖剥夺（OGD）可上调荷马1a的表达，并且荷马1a的过表达可减轻OGD诱导的培养皮质神经元中乳酸脱氢酶（LDH）释放和细胞死亡。OGD处理后，荷马1a的过表达维持了线粒体功能，表现为细胞色素c释放减少、活性氧（ROS）生成减少、ATP和线粒体膜电位（MMP）损失减少、半胱天冬酶-9激活减少，以及通过磷酸化-PKR样内质网激酶（p-PERK）/PERK和磷酸化-肌醇需求酶1（p-IRE1）/IRE1表达降低及免疫荧光（IF）染色证实的内质网（ER）应激受到抑制。此外，内质网应激激活剂衣霉素（TM）阻断了荷马1a对线粒体的保护作用，导致ROS水平再次升高，ATP和MMP损失增加。此外，通过用TM和p-IRE1抑制剂3,5-二溴水杨醛（DBSA）激活PERK途径，显著逆转了荷马1a过表达诱导的线粒体应激减轻，表现为细胞色素c释放增加、ATP损失增加和ROS水平升高。然而，用TM和p-PERK抑制剂GSK2656157激活IRE1途径，细胞色素c释放变化不大，神经元中ATP损失和ROS生成有适度增加。总之，这些发现表明，荷马1a通过抑制PERK途径维持线粒体功能，从而保护细胞免受OGD诱导的损伤。我们的发现可能揭示了一个保护神经元免受脑I/R损伤的有前景的靶点。
