School of Chinese Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China.
J Proteome Res. 2011 Jan 7;10(1):299-304. doi: 10.1021/pr100871h. Epub 2010 Dec 14.
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.
为了鉴定五味子乙素（Sch B）发挥肝保护作用所涉及的关键蛋白，我们采用蛋白质组学方法筛选出 Sch B 特异性调节的小鼠肝蛋白，并研究这些蛋白在肝保护中的作用。有 13 种蛋白被 Sch B 处理特异性激活或抑制。在这 13 种蛋白中，推测 Raf 激酶抑制剂蛋白（RKIP）是参与肝毒素诱导的细胞损伤发展的关键调节蛋白。结果表明，反义 RKIP 载体转染下调 RKIP 导致 Raf-1/MEK/ERK 信号通路的激活，这表现在 MEK/ERK 磷酸化水平和核内红细胞系 2 相关因子 2 的水平升高。RKIP 下调产生的信号作用类似于 Sch B 触发的作用，这两种处理都导致 AML12 肝细胞中四氯化碳诱导的凋亡细胞死亡程度降低。通过正义 RKIP 转染载体过表达 RKIP 或通过 PD98059 抑制 MEK 激酶，均可消除 Sch B 在肝细胞中的细胞保护作用。结果表明，Sch B 通过下调 RKIP 触发 Raf/MEK/ERK 信号通路，从而防止四氯化碳诱导的细胞毒性。
