Gressner Olav A, Lahme Birgit, Demirci Ilhan, Gressner Axel M, Weiskirchen Ralf
Institute of Clinical Chemistry and Pathobiochemistry, RWTH-University Hospital, D-52074 Aachen, Germany.
J Hepatol. 2007 Nov;47(5):699-710. doi: 10.1016/j.jhep.2007.05.015. Epub 2007 Jun 26.
BACKGROUND/AIMS: Connective tissue growth factor (CTGF/CCN2) has been implicated in the pathogenesis of hepatic fibrosis and suggested as a downstream mediator of the fibrogenic master cytokine TGF-beta.
We investigated the effect of TGF-beta1 on CTGF/CCN2 expression in cultured rat hepatic stellate cells and hepatocytes by means of Western and Northern blotting, immunocytochemistry, reporter gene analysis, and metabolic labelling.
We found that the expression of CTGF/CCN2 in hepatic stellate cells is (i) only marginally (if at all) stimulated by TGF-beta and by a constitutively active type I TGF-beta receptor, (ii) independent from Smad2/3 phosphorylation, (iii) not reduced by TGF-beta1 antagonists or ALK5-receptor inhibitors and (iv) not upregulated during transdifferentiation to myofibroblasts in culture. However, expression and secretion of CTGF/CCN2 in cultured hepatocytes increased spontaneously during culture and was strongly stimulated by TGF-beta1. In bile-duct ligated and CCl(4)-treated rat livers, a strong CTGF/CCN2 expression in hepatocytes was noticed. Endothelin-1 stimulated CTGF/CCN2 expression in stellate cells but not in hepatocytes. Pathway specific signalling inhibitors point to the involvement of non-Smad signalling cascades but their contribution to CTGF/CCN2 regulation is different in both cell types.
The results do not reveal a relevant interrelation between TGF-beta function and CTGF/CCN2 expression in hepatic stellate cells, which is in contrast to hepatocytes.
背景/目的：结缔组织生长因子（CTGF/CCN2）与肝纤维化的发病机制有关，被认为是促纤维化主要细胞因子转化生长因子-β（TGF-β）的下游介质。
我们通过蛋白质免疫印迹法、Northern印迹法、免疫细胞化学、报告基因分析和代谢标记法，研究了TGF-β1对培养的大鼠肝星状细胞和肝细胞中CTGF/CCN2表达的影响。
我们发现，肝星状细胞中CTGF/CCN2的表达：（i）仅受到TGF-β和组成型活性I型TGF-β受体的微弱刺激（如果有的话）；（ii）独立于Smad2/3磷酸化；（iii）不受TGF-β1拮抗剂或ALK5受体抑制剂的影响；（iv）在培养过程中转分化为肌成纤维细胞时不会上调。然而，培养的肝细胞中CTGF/CCN2的表达和分泌在培养过程中自发增加，并受到TGF-β1的强烈刺激。在胆管结扎和CCl4处理的大鼠肝脏中，观察到肝细胞中有强烈的CTGF/CCN2表达。内皮素-1刺激星状细胞中CTGF/CCN2的表达，但不刺激肝细胞中的表达。通路特异性信号抑制剂表明非Smad信号级联参与其中，但它们对CTGF/CCN2调节的作用在两种细胞类型中有所不同。
结果表明，与肝细胞相反，TGF-β功能与肝星状细胞中CTGF/CCN2表达之间不存在相关的相互关系。
