Endoplasmic reticulum pathology and stress response in neurons precede programmed necrosis after neonatal hypoxia-ischemia.
Endoplasmic reticulum pathology and stress response in neurons precede programmed necrosis after neonatal hypoxia-ischemia.
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DOI：
10.1016/j.ijdevneu.2015.11.007
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发表时间：
2016-02
期刊：
影响因子：
--
通讯作者：
Northington FJ
中科院分区：
文献类型：
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作者：
Chavez-Valdez R;Flock DL;Martin LJ;Northington FJ
在许多功能中，内质网(ER)的任务是防止新生儿缺氧缺血(HI)后的兴奋性毒性杀死神经元。随着对新生儿缺氧缺血性脑病延迟治疗方法的寻找，延迟ER反应的研究变得有意义。我们假设内质网应激是新生儿缺氧缺血性脑病后通过程序性坏死导致迟发性神经元死亡的一个显著特征。由于NEC-1(NEC-1)是一种程序性坏死的抑制剂，在雄性小鼠中对新生HI具有延迟性神经保护作用，因此NEC-1是研究延迟性ER反应的理想工具。C57B6雄性小鼠在右侧颈动脉结扎后，暴露于P7，FiO2=0.08，持续45min。给小鼠脑室内注射赋形剂或NEC-1(0.1mmol8μL)，并以同龄胎鼠为对照。分别于缺氧缺血后3h、2 4h进行生化检测，96h进行电子显微镜(EM)和免疫组织化学检查。EM表现为神经元早期明显的内质网扩张和线粒体肿胀。随着神经退变的进展，含有扩张的ER的大的细胞质碎片“脱落”到周围的神经纤维和钙网蛋白免疫反应性丢失，同时伴随着提示程序性坏死的核特征。NEC-1降低了新生儿缺氧缺血后内质网应激的生化标志物，包括PERK和eIF2XBP-1的α磷酸化，以及非常规的XBP-1剪接，这与后来的内质网病理的缓解一致。ER病理可能是神经元损伤严重程度和恢复潜力的指标，其特征是胞浆脱落不同于凋亡性气泡，我们称之为神经元巨细胞增多症。延迟期应用减轻内质网应激的治疗可能挽救新生儿缺氧缺血性脑病后的应激神经元。
The endoplasmic reticulum (ER) is tasked, among many other functions, with preventing excitotoxicity from killing neurons following neonatal hypoxia-ischemia (HI). With the search for delayed therapies to treat neonatal HI, the study of delayed ER responses becomes relevant. We hypothesized that ER stress is a prominent feature of delayed neuronal death via programmed necrosis after neonatal HI. Since Necrostatin-1 (Nec-1), an inhibitor of programmed necrosis, provides delayed neuroprotection against neonatal HI in male mice, Nec-1 is an ideal tool to study delayed ER responses. C57B6 male mice were exposed to right carotid ligation followed by exposure to FiO2=0.08 for 45 min at p7. Mice were treated with vehicle or Nec-1 (0.1 μl of 8 μmol) intracerebroventricularly with age-matched littermates as controls. Biochemistry assays at 3 and 24h and electron microscopy (EM) and immunohistochemistry at 96h after HI were performed. EM showed ER dilation and mitochondrial swelling as apparent early changes in neurons. With advanced neurodegeneration, large cytoplasmic fragments containing dilated ER “shed” into the surrounding neuropil and calreticulin immunoreactivity was lost concurrent with nuclear features suggestive of programmed necrosis. Nec-1 attenuated biochemical markers of ER stress after neonatal HI, including PERK and eIF2α phosphorylation, and unconventional XBP-1 splicing, consistent with the mitigation of later ER pathology. ER pathology may be an indicator of severity of neuronal injury and potential for recovery characterized by cytoplasmic shedding distinct from apoptotic blebbing, that we term neuronal macrozeiosis. Therapies to attenuate ER stress applied at delayed stages may rescue stressed neurons after neonatal HI.