Table_1_RETRACTED: ErbB4 Preserves Blood-Brain Barrier Integrity via the YAP/PIK3CB Pathway After Subarachnoid Hemorrhage in Rats.DOCX

Studies have suggested that blood-brain barrier (BBB) disruption contributes to the pathogenesis of early brain injury after subarachnoid haemorrhage (SAH). Activation of the receptor tyrosine kinase ErbB4 can cause intramembrane proteolysis and release a soluble intracellular domain (ICD) that modulates transcription in the nucleus. This study was carried out to investigate the potential roles of ErbB4 in preserving BBB integrity after experimental SAH, as well as the underlying mechanisms of its protective effects. Endovascular perforation was used to prepare a rat SAH model. The SAH grade, neurological score, brain edema and BBB permeability were evaluated after surgery. Immunohistochemistry was used to determine the localization of ErbB4 and yes-associated protein (YAP). ErbB4 activator Nrg1 isoform β1 (Nrg1β1), Specific ErbB4 siRNA, YAP siRNA and PIK3CB specific inhibitor TGX 221 were used to manipulate the proposed pathway. The expression levels of ErbB4 ICD and YAP were markly increased after SAH. Double immunohistochemistry labeling showed that ErbB4 and YAP were expressed in endothelial cells and neurons. Activation of ErbB4 by Nrg1β1 (dosage 150 ng/kg) treatment promoted the neurobehavioral deficit, alleviated the brain water content and reduced albumin leakage 24 and 72 h after SAH. ErbB4 activation significantly promoted YAP and PIK3CB activity and increased the expression of tight junction proteins Occludin and Claudin-5. Depletion of ErbB4 aggravated neurological impairment and BBB disruption after SAH. The beneficial effects of ErbB4 activation were abolished by YAP small-interfering RNA and specific PIK3CB inhibitor. Activation of ErbB4 improved neurological performance after SAH through the YAP/PIK3CB signaling pathway, this neuroprotective effects may associated with BBB maintenance.

已有研究表明，血脑屏障（blood-brain barrier, BBB）破坏参与蛛网膜下腔出血（subarachnoid haemorrhage, SAH）后早期脑损伤的发病过程。受体酪氨酸激酶ErbB4的激活可诱导膜内蛋白水解，释放可溶性细胞内结构域（intracellular domain, ICD），后者可调控细胞核内的转录活动。本研究旨在探究ErbB4在实验性SAH后维持BBB完整性中的潜在作用，及其发挥保护作用的潜在分子机制。本研究采用血管内穿刺法构建大鼠SAH模型，于术后评估大鼠的SAH分级、神经功能评分、脑水肿程度及BBB通透性。采用免疫组织化学法检测ErbB4与yes相关蛋白（yes-associated protein, YAP）的定位表达。通过ErbB4激活剂Nrg1亚型β1（Nrg1β1）、特异性ErbB4小干扰RNA（small-interfering RNA, siRNA）、YAP siRNA及PIK3CB特异性抑制剂TGX 221对目标信号通路进行干预调控。实验结果显示，SAH发生后，ErbB4 ICD与YAP的表达水平显著升高。双重免疫组织化学标记结果表明，ErbB4与YAP均表达于内皮细胞及神经元中。给予150 ng/kg剂量的Nrg1β1以激活ErbB4，可加重SAH后24小时及72小时的神经行为缺陷，同时减轻脑含水量并减少白蛋白渗漏。ErbB4激活可显著增强YAP与PIK3CB的活性，并上调紧密连接蛋白Occludin与Claudin-5的表达水平。敲低ErbB4可加重SAH后的神经功能损伤与BBB破坏。ErbB4激活所产生的有益效应可被YAP siRNA及PIK3CB特异性抑制剂所阻断。本研究证实，ErbB4激活可通过YAP/PIK3CB信号通路改善SAH后的神经功能，其神经保护效应可能与维持BBB完整性相关。