Transforming growth factor β1 induces the expression of α1(I) procollagen mRNA by a hydrogen peroxide-C/EBPβ-dependent mechanism in rat hepatic stellate cells
Transforming growth factor β1 induces the expression of α1(I) procollagen mRNA by a hydrogen peroxide-C/EBPβ-dependent mechanism in rat hepatic stellate cells
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DOI：
10.1002/hep.510290346
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发表时间：
1999-03-01
期刊：
影响因子：
13.5
通讯作者：
Rojkind, M
中科院分区：
文献类型：
--
作者：
García-Trevijano, ER;Iraburu, MJ;Rojkind, M
氧化应激在肝纤维化中起着关键作用，炎症细胞和活化的库普弗细胞都会产生H2O2，H2O2是一种参与肝星状细胞（HSC）活化的氧化剂。纤维化肝脏中活性氧中间体 (ROI) 产生的增加部分与转化生长因子 β (TGF-β) 的上调有关，这种细胞因子可增强培养的 HSC 产生的胶原蛋白。然而，氧化应激与 TGF-β 诱导 HSC 胶原基因表达的分子机制之间可能存在的联系仍有待阐明。为了解决这个问题，我们研究了 H2O2 是否是 TGF-β 引发的 α1(I) 胶原蛋白基因（胶原蛋白）上调的介质。我们证明 TGF-β 会诱导 H2O2 的积累，而这种氧化剂反过来又直接参与上调 col1a1 基因的表达。虽然向HSC添加H 2 O 2 诱导al(I)前胶原mRNA的表达，但过氧化氢酶(一种H 2 O 2 酶清除剂)消除了TGF-β介导的胶原基因上调。我们用由小鼠 Collal 启动子的不同片段驱动的嵌合质粒转染 HSC，并定位了 TGF-β 反应性所必需的顺式作用元件（-370 至 -344）。我们进一步表明，TGF-β 诱导含有 C/EBP β 的转录复合物激活并与该序列结合，这种效果也可以通过添加 H2O2 来模拟。总而言之，这些数据证明了 TGF-β 介导的 H2O2 积累与 HSC 中 col1a1 基因的上调之间存在直接联系。
Oxidative stress plays a key role in liver fibrosis, Both inflammatory cells and activated Kupffer cells produce H2O2, an oxidant involved in the activation of hepatic stellate cells (HSC). Increased production of reactive oxygen intermediates (ROIs) in fibrotic livers is associated in part with the up-regulation of transforming growth factor beta (TGF-beta), and this cytokine enhances collagen production by cultured HSC. However, the possible link between oxidative stress and the molecular mechanisms by which TGF-beta induces collagen gene expression in HSC remains to be elucidated. To address this question, we investigated whether H2O2 is a mediator of TGF-beta-elicited alpha 1(I) collagen gene (collal) up-regulation. We demonstrated that TGF-beta induces the accumulation of H2O2, and that this oxidant is, in turn, directly involved in up-regulating the expression of the col1a1 gene. While the addition of H2O2 to HSC induced the expression of al(I) procollagen mRNA, catalase, an H2O2 enzyme scavenger, abrogated TGF-beta-mediated collal gene up-regulation. We transfected HSC with chimeric plasmids driven by different segments of the mouse collal promoter and mapped a cis-acting element (-370 to -344) essential for TGF-beta responsiveness. We further showed that TGF-beta induced the activation and binding of a C/EBP beta-containing transcriptional complex to this sequence, an effect that was also mimicked by the addition of H2O2. Taken together, these data demonstrate a direct connection between TGF-beta-mediated accumulation of H2O2 and the up-regulation of col1a1 gene in HSC.