title: A proteomic approach in investigating the hepatoprotective mechanism of Schisandrin B: role of raf kinase inhibitor protein.
abstract: To identify key proteins involved in the hepatoprotection afforded by schisandrin B (Sch B), we used a proteomic approach to screen proteins that were specifically regulated by Sch B in mouse livers and to investigate the role of the proteins in hepatoprotection. Thirteen proteins were specifically activated or suppressed by Sch B treatment. Among the 13 proteins, Raf kinase inhibitor protein (RKIP) was postulated to be the key regulator involved in the development of hepatotoxin-induced cellular damage. The results indicated that the downregulation of RKIP by antisense RKIP vector transfection led to the activation of the Raf-1/MEK/ERK signaling pathway, as evidenced by increases in the level of MEK/ERK phosphorylation and the level of nuclear factor erythroid 2-related factor 2 in the nucleus. The signaling effect produced by RKIP downregulation resembled that triggered by Sch B, wherein both treatments resulted in a decrease in the extent of carbon tetrachloride-induced apoptotic cell death in AML12 hepatocytes. Overexpression of RKIP by the sense RKIP transfection vector or the inhibition of MEK kinase by PD98059 was able to abrogate the cytoprotective effect of Sch B in the hepatocytes. The results indicate that Sch B triggers the Raf/MEK/ERK signaling pathway, presumably by downregulating RKIP, thereby protecting against carbon tetrachloride-induced cytotoxicity.
authors.affiliation: School of Chinese Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Chen
authors.forename: Siu-Po
authors.initials: SP
authors.lastname: Ip
authors.forename: Kam-Ming
authors.initials: KM
authors.lastname: Ko
authors.forename: Terence C W
authors.initials: TC
authors.lastname: Poon
authors.forename: Eddy W Y
authors.initials: EW
authors.lastname: Ng
authors.forename: Paul B S
authors.initials: PB
authors.lastname: Lai
authors.forename: Qing-Qiu
authors.initials: QQ
authors.lastname: Mao
authors.forename: Yan-Fang
authors.initials: YF
authors.lastname: Xian
authors.forename: Chun-Tao
authors.initials: CT
authors.lastname: Che
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002251:Carbon Tetrachloride / Q000633:toxicity; D056486:Chemical and Drug Induced Liver Injury / Q000188:drug therapy / Q000517:prevention & control; D034242:Cyclooctanes / Q000494:pharmacology; D015180:Electrophoresis, Gel, Two-Dimensional; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D017705:Lignans / Q000494:pharmacology*; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D049488:Phosphatidylethanolamine Binding Protein / Q000737:chemistry / Q000378:metabolism*; D011083:Polycyclic Compounds / Q000494:pharmacology*; D020011:Protective Agents / Q000494:pharmacology*; D011506:Proteins / Q000737:chemistry / Q000145:classification / Q000378:metabolism; D020543:Proteome / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D040901:Proteomics / Q000379:methods*; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D018709:Statistics, Nonparametric
chemical_list: D034242:Cyclooctanes; D017705:Lignans; D049488:Phosphatidylethanolamine Binding Protein; D011083:Polycyclic Compounds; D020011:Protective Agents; D011506:Proteins; D020543:Proteome; C539308:Raf kinase inhibitory protein, mouse; C015499:schizandrin B; D002251:Carbon Tetrachloride; D019908:Proto-Oncogene Proteins c-raf; D048049:Extracellular Signal-Regulated MAP Kinases; D020930:MAP Kinase Kinase Kinases