title: Potential role of microRNA-7 in the anti-neuroinflammation effects of nicorandil in astrocytes induced by oxygen-glucose deprivation.
abstract: BACKGROUND
  It is generally recognized that the inflammatory reaction in glia is one of the important pathological factors in brain ischemic injury. Our previous study has revealed that opening ATP-sensitive potassium (K-ATP) channels could attenuate glial inflammation induced by ischemic stroke. However, the detailed mechanisms are not well known.
  
  
  METHODS
  Primary cultured astrocytes separated from C57BL/6 mice were subjected to oxygen-glucose deprivation (OGD); cellular injuries were determined via observing the changes of cellular morphology and cell viability. MicroRNA (miR) and messenger RNA (mRNA) level was validated by real-time PCR. The interaction between microRNA and the target was confirmed via dual luciferase reporter gene assay. Expressions of proteins and inflammatory cytokines were respectively assessed by western blotting and enzyme-linked immunosorbent assay.
  
  
  RESULTS
  OGD resulted in astrocytic damage, which was prevented by K-ATP channel opener nicorandil. Notably, we found that OGD significantly downregulated miR-7 and upregulated Herpud2. Our further study proved that miR-7 targeted Herpud2 3'UTR, which encoded endoplasmic reticulum (ER) stress protein-HERP2. Correspondingly, our results showed that OGD increased the levels of ER stress proteins along with significant elevations of pro-inflammatory cytokines, including tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β). Pretreatment with nicorandil could remarkably upregulate miR-7, depress the ER-related protein expressions including glucose-regulated protein 78 (GRP78), C/EBP-homologous protein (CHOP), and Caspase-12, and thereby attenuate inflammatory responses and astrocytic damages.
  
  
  CONCLUSIONS
  These findings demonstrate that opening K-ATP channels protects astrocytes against OGD-mediated neuroinflammation. Potentially, miR-7-targeted ER stress acts as a key molecular brake on neuroinflammation.
authors.affiliation: Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China. dongyf@njucm.edu.cn.|School of Nursing, Nanjing University of Chinese Medicine, Nanjing, China. dongyf@njucm.edu.cn.
authors.forename: Yin-Feng
authors.initials: YF
authors.lastname: Dong
authors.affiliation: Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China. 792227868@qq.com.
authors.forename: Zheng-Zhen
authors.initials: ZZ
authors.lastname: Chen
authors.affiliation: Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China. bainianzhaoyao@qq.com.
authors.forename: Zhan
authors.initials: Z
authors.lastname: Zhao
authors.affiliation: Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China. 805525657@qq.com.
authors.forename: Dan-Dan
authors.initials: DD
authors.lastname: Yang
authors.affiliation: Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China. 1057914826@qq.com.
authors.forename: Hui
authors.initials: H
authors.lastname: Yan
authors.affiliation: Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China. 1041347753@qq.com.
authors.forename: Juan
authors.initials: J
authors.lastname: Ji
authors.affiliation: Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China. xiulans@njmu.edu.cn.
authors.forename: Xiu-Lan
authors.initials: XL
authors.lastname: Sun
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D001253:Astrocytes / Q000187:drug effects* / Q000648:ultrastructure; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism; D015687:Cell Hypoxia / Q000187:drug effects*; D002470:Cell Survival; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D005947:Glucose / Q000172:deficiency*; D007249:Inflammation / Q000188:drug therapy* / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000187:drug effects / Q000502:physiology*; D020108:Nicorandil / Q000494:pharmacology*; D015221:Potassium Channels / Q000819:agonists*; D061251:Primary Cell Culture; D012097:Repressor Proteins / Q000378:metabolism
chemical_list: D000893:Anti-Inflammatory Agents; D051792:Basic Helix-Loop-Helix Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; D005947:Glucose; D035683:MicroRNAs; D020108:Nicorandil; D015221:Potassium Channels; D012097:Repressor Proteins; C485778:Hey2 protein, mouse; C000717248:Hspa5 protein, mouse; C549243:MIRN7 microRNA, mouse