Involvement of endoplasmic reticulum stress in the necroptosis of microglia/macrophages after spinal cord injury. (17th December 2015)

• Record Type: Journal Article
• Authors: Fan, H.; Tang, H.-B.; Kang, J.; Shan, L.; Song, H.; Zhu, K.; Wang, J.; Ju, G.; Wang, Y.-Z.
• Is Part Of: Neuroscience. Volume 311(2015)
• Page Start: 362
• Page End: 373
• Publication Date: 2015-12-17
• Subjects: 4-PBA 4-phenylbutyrate -- CC3 cleaved Caspase-3 -- CXCR4 chemokine (C-X-C motif) receptor 4 -- DMEM Dulbecco's modified Eagle medium -- EDTA ethylenediaminetetraacetic acid -- EM electronic microscopic -- ER endoplasmic reticulum -- FBS fetal bovine serum -- GRP78 Glucose-regulated protein 78 -- HMGB1 high-mobility group box protein 1 -- MLKL mixed lineage kinase domain-like protein -- Nec-1 Necrostatin-1 -- NGS normal goat serum -- OGD oxygen–glucose deprivation -- PBS phosphate-buffered saline -- PI Propidium Iodide -- pMLKL phosphorylated MLKL -- PMSF phenylmethylsulfonyl fluoride -- RIP1 receptor-interacting protein 1 -- RIP3 receptor-interacting protein 3 -- SCI spinal cord injury; spinal cord injury -- microglia/macrophage -- necroptosis -- ER stress; Neurochemistry -- Periodicals; Neurophysiology -- Periodicals; Neurology -- Periodicals; Neurochimie -- Périodiques; Neurophysiologie -- Périodiques; Neurochemistry; Neurophysiology; Electronic journals; Periodicals; Electronic journals; 612.8
• DOI: 10.1016/j.neuroscience.2015.10.049
• Languages: English
• ISSNs: 0306-4522

Abstract

Graphical abstract: Highlights: Necroptosis occurs in microglia/macrophages after spinal cord injury. MLKL and RIP3 localize at endoplasmic reticulum of necrotic microglia/macrophages. Endoplasmic reticulum stress leads to necroptosis of N9 microglial cells in vitro . Inhibiting endoplasmic reticulum stress reduces necroptosis of microglia in vitro . pMLKL and GRP78 are expressed by microglia/macrophages in the injured human spinal cord. Abstract: Microglia/macrophages play a crucial role in inflammation after spinal cord injury (SCI). Although extensive studies have been performed on the mechanisms of microglia/macrophage activation and recruitment, how microglia/macrophages are eliminated remains unclear. In the present study, we observed a high-level expression of mixed lineage kinase domain-like protein (MLKL), a key molecule in the execution of necroptosis, in microglia/macrophages after SCI in mice. In vivo PI-labeling and Necrostatin-1 treatment confirmed the necroptosis of microglia/macrophages. Interestingly, our electronic microscopic (EM) study revealed that MLKL localized not only at the membrane but also on the endoplasmic reticulum (ER) of necroptotic microglia/macrophages. Furthermore, receptor-interacting protein 3 (RIP3), another necrosome component, was also found on the ER of necroptotic microglia/macrophages. And Glucose-regulated protein 78 (GRP78), an ER stress sensor, was up-regulated in MLKL-positive microglia/macrophages after SCI, suggesting a possible link between necroptosis and ER stress. In vitro, oxygen–glucose deprivation (OGD) stress induced ER stress and necroptosis in microglia. Inhibiting ER stress by 4-phenylbutyrate (4-PBA) significantly blocked the OGD-induced necroptosis of microglia. In the end, our data showed that, GRP78 and phosphorylated MLKL were co-expressed by the microglia/macrophages in the injured human spinal cord. Taken together, these results suggested that microglia/macrophages undergo an ER-stress involved necroptosis after SCI, implying that ER stress and necroptosis could be manipulated for modulating inflammation post-SCI.