title: Japanese encephalitis virus induces matrix metalloproteinase-9 in rat brain astrocytes via NF-κB signalling dependent on MAPKs and reactive oxygen species.
abstract: OBJECTIVE
  Japanese encephalitis virus (JEV) is a member of the family Flaviviridae and JEV infection is a major cause of acute encephalopathy in children, which destroys cells in the CNS, including astrocytes and neurons. However, the detailed mechanisms underlying the inflammatory action of JEV are largely unclear.
  
  
  METHODS
  The effect of JEV on the expression of matrix metalloproteinase (MMP)-9 was determined by gelatin zymography, Western blot analysis, real-time PCR and promoter assay. The involvement of the NADPH oxidase and reactive oxygen species (ROS), MAPKs, and the transcription factor NF-κB in these responses was investigated by using selective pharmacological inhibitors and transfection with appropriate siRNAs.
  
  
  RESULTS
  JEV induced the expression of the pro-form of MMP-9 in rat brain astrocytes (RBA-1 cells). In RBA-1 cells, JEV induced MMP-9 expression and promoter activity, which was inhibited by pretreatment with inhibitors of NADPH oxidase (diphenylene iodonium chloride or apocynin), MAPKs (U0126, SB203580 or SP600125) and a ROS scavenger (N-acetylcysteine), or transfection with siRNAs of p47(phox) , ERK1, JNK2 and p38. In addition, JEV-induced MMP-9 expression was reduced by pretreatment with an inhibitor of NF-κB (helenalin) or transfection with p65 siRNA. Moreover, JEV-stimulated NF-κB activation was inhibited by pretreatment with the inhibitors of NADPH oxidase and MAPKs.
  
  
  CONCLUSIONS
  MMP-9 expression induced by JEV infection of RBA-1 cells was mediated through the generation of ROS and activation of p42/p44 MAPK, p38 MAPK and JNK1/2, leading to NF-κB activation.
authors.affiliation: Department of Physiology and Pharmacology, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan.
authors.forename: Wei-Hsuan
authors.initials: WH
authors.lastname: Tung
authors.forename: Hsin-Wen
authors.initials: HW
authors.lastname: Tsai
authors.forename: I-Ta
authors.initials: IT
authors.lastname: Lee
authors.forename: Hsi-Lung
authors.initials: HL
authors.lastname: Hsieh
authors.forename: Wei-June
authors.initials: WJ
authors.lastname: Chen
authors.forename: Yuh-Lien
authors.initials: YL
authors.lastname: Chen
authors.forename: Chuen-Mao
authors.initials: CM
authors.lastname: Yang
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000201:enzymology / Q000378:metabolism* / Q000821:virology*; D001921:Brain / Q000201:enzymology / Q000473:pathology; D002460:Cell Line; D004664:Encephalitis Virus, Japanese / Q000502:physiology*; D004672:Encephalitis, Japanese / Q000378:metabolism / Q000821:virology; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D051379:Mice; D008813:Mice, Inbred ICR; D048055:Mitogen-Activated Protein Kinase 8 / Q000378:metabolism; D048056:Mitogen-Activated Protein Kinase 9 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D019255:NADPH Oxidases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction; D014162:Transfection
chemical_list: D016328:NF-kappa B; D017382:Reactive Oxygen Species; D019255:NADPH Oxidases; D048056:Mitogen-Activated Protein Kinase 9; D048055:Mitogen-Activated Protein Kinase 8; D020928:Mitogen-Activated Protein Kinases; D020780:Matrix Metalloproteinase 9