title: Involvement of endoplasmic reticulum stress in the necroptosis of microglia/macrophages after spinal cord injury.
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.
authors.affiliation: Department of Neurobiology and Collaborative Innovation Center for Brain Science, Institute of Neurosciences, Fourth Military Medical University, 169 Chang Le Xi Road, Xi'an 710032, China.
authors.forename: H
authors.initials: H
authors.lastname: Fan
authors.affiliation: Department of Clinical Laboratory Medicine, Xijing Hospital, Fourth Military Medical University, 127 Chang Le Xi Road, Xi'an 710003, China.
authors.forename: H-B
authors.initials: HB
authors.lastname: Tang
authors.affiliation: Department of Neurobiology and Collaborative Innovation Center for Brain Science, Institute of Neurosciences, Fourth Military Medical University, 169 Chang Le Xi Road, Xi'an 710032, China.
authors.forename: J
authors.initials: J
authors.lastname: Kang
authors.affiliation: Department of Orthopedics, Tangdu Hospital, Fourth Military Medical University, Xin Si Road, Xi'an, Shaanxi 710038, China.
authors.forename: L
authors.initials: L
authors.lastname: Shan
authors.affiliation: Department of Occupational and Environmental Health, School of Public Health, Fourth Military Medical University, Xi'an 710032, China.
authors.forename: H
authors.initials: H
authors.lastname: Song
authors.affiliation: Zhejiang University China Brain Bank, Department of Pathology and Pathophysiology, Department of Neuroscience, 866 Yu-Hang-Tang Road, Zhejiang University Zi-Jin-Gang Campus, Hangzhou, Zhejiang 310058, China.
authors.forename: K
authors.initials: K
authors.lastname: Zhu
authors.affiliation: Department of Neurobiology and Collaborative Innovation Center for Brain Science, Institute of Neurosciences, Fourth Military Medical University, 169 Chang Le Xi Road, Xi'an 710032, China.
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Neurobiology and Collaborative Innovation Center for Brain Science, Institute of Neurosciences, Fourth Military Medical University, 169 Chang Le Xi Road, Xi'an 710032, China. Electronic address: jugong@fmmu.edu.cn.
authors.forename: G
authors.initials: G
authors.lastname: Ju
authors.affiliation: Department of Neurobiology and Collaborative Innovation Center for Brain Science, Institute of Neurosciences, Fourth Military Medical University, 169 Chang Le Xi Road, Xi'an 710032, China. Electronic address: yazhouw@fmmu.edu.cn.
authors.forename: Y-Z
authors.initials: YZ
authors.lastname: Wang
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004195:Disease Models, Animal; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects / Q000502:physiology*; D006360:Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D008264:Macrophages / Q000187:drug effects / Q000473:pathology / Q000502:physiology*; D008297:Male; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000187:drug effects / Q000473:pathology / Q000502:physiology*; D009336:Necrosis / Q000188:drug therapy / Q000473:pathology / Q000503:physiopathology; D018696:Neuroprotective Agents / Q000494:pharmacology; D010654:Phenylbutyrates / Q000494:pharmacology; D011494:Protein Kinases / Q000378:metabolism; D053422:Receptor-Interacting Protein Serine-Threonine Kinases / Q000378:metabolism; D013119:Spinal Cord Injuries / Q000188:drug therapy / Q000473:pathology / Q000503:physiopathology*
chemical_list: D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; C000717248:Hspa5 protein, mouse; D018696:Neuroprotective Agents; D010654:Phenylbutyrates; C075773:4-phenylbutyric acid; C570693:MLKL protein, human; C570694:MLKL protein, mouse; D011494:Protein Kinases; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; C485615:Ripk3 protein, mouse
keywords: ER stress; microglia/macrophage; necroptosis; spinal cord injury