title: Japanese encephalitis virus induces matrix metalloproteinase-9 expression via a ROS/c-Src/PDGFR/PI3K/Akt/MAPKs-dependent AP-1 pathway in rat brain astrocytes.
abstract: BACKGROUND
  Japanese encephalitis virus (JEV) infection is a major cause of acute encephalopathy in children, which destroys central nervous system (CNS) cells, including astrocytes and neurons. Matrix metalloproteinase (MMP)-9 has been shown to degrade components of the basal lamina, leading to disruption of the blood-brain barrier (BBB) and to contribute to neuroinflammatory responses in many neurological diseases. However, the detailed mechanisms of JEV-induced MMP-9 expression in rat brain astrocytes (RBA-1 cells) are largely unclear.
  
  
  METHODS
  In this study, the effect of JEV on expression of MMP-9 was determined by gelatin zymography, western blot analysis, RT-PCR, and promoter assay. The involvement of AP-1 (c-Jun and c-Fos), c-Src, PDGFR, PI3K/Akt, and MAPKs in these responses were investigated by using the selective pharmacological inhibitors and transfection with siRNAs.
  
  
  RESULTS
  Here, we demonstrate that JEV induces expression of pro-form MMP-9 via ROS/c-Src/PDGFR/PI3K/Akt/MAPKs-dependent, AP-1 activation in RBA-1 cells. JEV-induced MMP-9 expression and promoter activity were inhibited by pretreatment with inhibitors of AP-1 (tanshinone), c-Src (PP1), PDGFR (AG1296), and PI3K (LY294002), and by transfection with siRNAs of c-Jun, c-Fos, PDGFR, and Akt. Moreover, JEV-stimulated AP-1 activation was inhibited by pretreatment with the inhibitors of c-Src, PDGFR, PI3K, and MAPKs.
  
  
  CONCLUSIONS
  From these results, we conclude that JEV activates the ROS/c-Src/PDGFR/PI3K/Akt/MAPKs pathway, which in turn triggers AP-1 activation and ultimately induces MMP-9 expression in RBA-1 cells. These findings concerning JEV-induced MMP-9 expression in RBA-1 cells imply that JEV might play an important role in CNS inflammation and diseases.
authors.affiliation: Department of Physiology and Pharmacology, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan. chuenmao@mail.cgu.edu.tw
authors.forename: Chuen-Mao
authors.initials: CM
authors.lastname: Yang
authors.forename: Chih-Chung
authors.initials: CC
authors.lastname: Lin
authors.forename: I-Ta
authors.initials: IT
authors.lastname: Lee
authors.forename: Yi-Hsin
authors.initials: YH
authors.lastname: Lin
authors.forename: Caleb M
authors.initials: CM
authors.lastname: Yang
authors.forename: Wei-June
authors.initials: WJ
authors.lastname: Chen
authors.forename: Mei-Jie
authors.initials: MJ
authors.lastname: Jou
authors.forename: Li-Der
authors.initials: LD
authors.lastname: Hsiao
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000378:metabolism* / Q000821:virology*; D001921:Brain / Q000166:cytology*; D002478:Cells, Cultured; D004664:Encephalitis Virus, Japanese / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015967:Gene Expression Regulation, Viral / Q000187:drug effects / Q000502:physiology*; D047468:Immunoprecipitation; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014162:Transfection
chemical_list: D004791:Enzyme Inhibitors; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D018808:Transcription Factor AP-1; D020780:Matrix Metalloproteinase 9