Institute of Clinical Chemistry and Pathobiochemistry, Central Laboratory, RWTH-University Hospital, 52074 Aachen, Germany.
World J Gastroenterol. 2011 Jan 14;17(2):151-63. doi: 10.3748/wjg.v17.i2.151.
To investigate the mechanisms involved in a possible modulator role of interleukin (IL)-6 signalling on CYR61-CTGF-NOV (CCN) 2/connective tissue growth factor (CTGF) expression in hepatocytes (PC) and to look for a relation between serum concentrations of these two parameters in patients with acute inflammation.
Expression of CCN2/CTGF, p-STAT3, p-Smad3/1 and p-Smad2 was examined in primary freshly isolated rat or cryo-preserved human PC exposed to various stimuli by Western blotting, electrophoretic mobility shift assay (EMSA), reporter-gene-assays and reverse-transcriptase polymerase chain reaction.
IL-6 strongly down-regulated CCN2/CTGF protein and mRNA expression in PC, enhanceable by extracellular presence of the soluble IL-6 receptor gp80, and supported by an inverse relation between IL-6 and CCN2/CTGF concentrations in patients' sera. The inhibition of TGFβ1 driven CCN2/CTGF expression by IL-6 did not involve a modulation of Smad2 (and Smad1/3) signalling. However, the STAT3 SH2 domain binding peptide, a selective inhibitor of STAT3 DNA binding activity, counteracted the inhibitory effect of IL-6 on CCN2/CTGF expression much more pronounced than pyrrolidine-dithiocarbamate, an inhibitor primarily of STAT3 phosphorylation. An EMSA confirmed STAT3 binding to the proposed proximal STAT binding site in the CCN2/CTGF promoter.
CCN2/CTGF is identified as a hepatocellular negative acute phase protein which is down-regulated by IL-6 via the STAT3 pathway through interaction on the DNA binding level.
研究白细胞介素（IL）-6 信号转导在肝细胞（PC）中对 CYR61-CTGF-NOV（CCN）2/结缔组织生长因子（CTGF）表达的可能调节剂作用的机制，并寻找这两种参数在急性炎症患者血清浓度之间的关系。
通过 Western blot、电泳迁移率变动分析（EMSA）、报告基因分析和逆转录聚合酶链反应，检测新鲜分离的大鼠或冷冻保存的人 PC 暴露于各种刺激物后 CCN2/CTGF、p-STAT3、p-Smad3/1 和 p-Smad2 的表达。
IL-6 强烈地下调了 PC 中的 CCN2/CTGF 蛋白和 mRNA 表达，细胞外存在可溶性 IL-6 受体 gp80 可增强这种下调作用，并且患者血清中 IL-6 和 CCN2/CTGF 浓度之间存在反比关系。IL-6 对 TGFβ1 驱动的 CCN2/CTGF 表达的抑制不涉及 Smad2（和 Smad1/3）信号转导的调节。然而，STAT3 SH2 结构域结合肽，一种选择性的 STAT3 DNA 结合活性抑制剂，比吡咯烷二硫代氨基甲酸盐更显著地拮抗 IL-6 对 CCN2/CTGF 表达的抑制作用，吡咯烷二硫代氨基甲酸盐主要抑制 STAT3 磷酸化。EMSA 证实 STAT3 与 CCN2/CTGF 启动子中提议的近端 STAT 结合位点结合。
CCN2/CTGF 被鉴定为一种肝细胞负急性相蛋白，其通过 IL-6 途径通过相互作用在 DNA 结合水平下调。
