肝细胞生长因子（HGF）通过 miRNA-29 的诱导抑制肝星状细胞中胶原 I 和 IV 的合成。
Hepatocyte growth factor (HGF) inhibits collagen I and IV synthesis in hepatic stellate cells by miRNA-29 induction.
机构信息
Institute for Pathology, University Hospital Cologne, Cologne, Germany.
出版信息
PLoS One. 2011;6(9):e24568. doi: 10.1371/journal.pone.0024568. Epub 2011 Sep 9.
BACKGROUND
In chronic liver disease, hepatic stellate cells (HSC) transdifferentiate into myofibroblasts, promoting extracellular matrix (ECM) synthesis and deposition. Stimulation of HSC by transforming growth factor-β (TGF-β) is a crucial event in liver fibrogenesis due to its impact on myofibroblastic transition and ECM induction. In contrast, hepatocyte growth factor (HGF), exerts antifibrotic activities. Recently, miR-29 has been reported to be involved in ECM synthesis. We therefore studied the influence of HGF and TGF-β on the miR-29 collagen axis in HSC.
METHODOLOGY
HSC, isolated from rats, were characterized for HGF and Met receptor expression by Real-Time PCR and Western blotting during culture induced myofibroblastic transition. Then, the levels of TGF-β, HGF, collagen-I and -IV mRNA, in addition to miR-29a and miR-29b were determined after HGF and TGF-β stimulation of HSC or after experimental fibrosis induced by bile-duct obstruction in rats. The interaction of miR-29 with 3'-untranslated mRNA regions (UTR) was analyzed by reporter assays. The repressive effect of miR-29 on collagen synthesis was studied in HSC treated with miR-29-mimicks by Real-Time PCR and immunoblotting.
PRINCIPAL FINDINGS
The 3'-UTR of the collagen-1 and -4 subtypes were identified to bind miR-29. Hence, miR-29a/b overexpression in HSC resulted in a marked reduction of collagen-I and -IV synthesis. Conversely, a decrease in miR-29 levels is observed during collagen accumulation upon experimental fibrosis, in vivo, and after TGF-β stimulation of HSC, in vitro. Finally, we show that during myofibroblastic transition and TGF-β exposure the HGF-receptor, Met, is upregulated in HSC. Thus, whereas TGF-β stimulation leads to a reduction in miR-29 expression and de-repression of collagen synthesis, stimulation with HGF was definitely associated with highly elevated miR-29 levels and markedly repressed collagen-I and -IV synthesis.
CONCLUSIONS
Upregulation of miRNA-29 by HGF and downregulation by TGF-β take part in the anti- or profibrogenic response of HSC, respectively.
背景
在慢性肝病中，肝星状细胞（HSC）向肌成纤维细胞转化，促进细胞外基质（ECM）的合成和沉积。转化生长因子-β（TGF-β）对 HSC 的刺激是肝纤维化形成的关键事件，因为它影响肌成纤维细胞的转化和 ECM 的诱导。相反，肝细胞生长因子（HGF）发挥抗纤维化作用。最近，miR-29 被报道参与 ECM 的合成。因此，我们研究了 HGF 和 TGF-β 对 HSC 中 miR-29 胶原轴的影响。
方法
通过实时 PCR 和 Western blot 分析培养诱导肌成纤维细胞转化过程中大鼠 HSC 中 HGF 和 Met 受体的表达，对其进行鉴定。然后，在 HGF 和 TGF-β刺激 HSC 或胆管阻塞诱导大鼠实验性纤维化后，测定 TGF-β、HGF、胶原-I 和 -IV mRNA 以及 miR-29a 和 miR-29b 的水平。通过报告基因分析检测 miR-29 与 3'-非翻译区（UTR）的相互作用。通过实时 PCR 和免疫印迹研究 HSC 用 miR-29-mimicks 处理后 miR-29 对胶原合成的抑制作用。
主要发现
鉴定出胶原-1 和 -4 亚型的 3'-UTR 与 miR-29 结合。因此，HSC 中 miR-29a/b 的过表达导致胶原-I 和 -IV 的合成明显减少。相反，在体内实验性纤维化过程中胶原积累、体外 TGF-β刺激 HSC 时，观察到 miR-29 水平降低。最后，我们表明，在肌成纤维细胞转化和 TGF-β暴露期间，HSC 中的 HGF 受体 Met 上调。因此，尽管 TGF-β 刺激导致 miR-29 表达减少和胶原合成去抑制，但 HGF 的刺激肯定与 miR-29 水平的显著升高以及胶原-I 和 -IV 合成的显著抑制有关。
结论
HGF 上调 miRNA-29 和 TGF-β 下调分别参与 HSC 的抗纤维化或促纤维化反应。
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