Fli1 and Ets1 have distinct roles in connective tissue growth factor/CCN2 gene regulation and induction of the profibrotic gene program
Fli1 and Ets1 have distinct roles in connective tissue growth factor/CCN2 gene regulation and induction of the profibrotic gene program
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DOI：
10.1074/jbc.m600466200
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发表时间：
2006-09-01
影响因子：
4.8
通讯作者：
Trojanowska, Maria
中科院分区：
文献类型：
--
作者：
Nakerakanti, Sashidhar S.;Kapanadze, Bagrat;Trojanowska, Maria
CCN 2（结缔组织生长因子）是血管生成、软骨形成和伤口愈合的重要调节因子，在大多数纤维化疾病和各种肿瘤中过表达。本研究探讨了Ets家族转录因子对CCN 2基因表达的调控，重点研究了在纤维化和肿瘤发生过程中表达失调的两个成员Fli 1和Ets 1。我们发现Ets 1和Fli 1对CCN 2基因表达有相反的影响。Ets 1作为CCN 2转录的激活因子发挥作用，而Fli 1作为阻遏因子发挥作用。在CCN 2启动子内的-114处定位功能性Ets结合位点。该位点不仅介导Ets因子（包括Ets 1、Ets 2和GABP α/β）的刺激，而且也是转化生长因子（TGF）-β反应所必需的。Ets 1和Fli 1在CCN 2基因调控中的对比功能通过使用表达特异性小干扰RNA的腺病毒载体抑制其内源性水平来证实。使用染色质免疫沉淀测定的其他实验显示，在成纤维细胞中，Ets 1和Fli 1都占据CCN 2启动子。TGF-β刺激导致Fli 1从CCN 2启动子的置换和Fli 1合成的瞬时抑制。此外，Fli 1表达的减少导致COL 1A 1和COL 1A 2基因的上调和MMP 1基因的下调。因此，抑制Fli 1重现了TGF-β的一些关键作用，表明Fli 1抑制参与了成纤维细胞中促纤维化基因程序的激活。另一方面，Ets 1下游CCN 2基因的激活与其在血管生成和细胞外基质重塑中的作用一致。这项研究强烈支持Fli 1和Ets 1在纤维化和癌症期间的病理性细胞外基质调节中的关键作用。
CCN2 (connective tissue growth factor), an important regulator of angiogenesis, chondrogenesis, and wound healing, is over-expressed in a majority of fibrotic diseases and in various tumors. This study investigated regulation of CCN2 gene expression by Ets family of transcription factors, focusing on two members, Fli1 and Ets1, with deregulated expression during fibrosis and tumorigenesis. We show that Ets1 and Fli1 have opposite effects on CCN2 gene expression. Ets1 functions as an activator of CCN2 transcription, whereas Fli1 acts as a repressor. A functional Ets binding site was mapped at -114 within the CCN2 promoter. This site not only mediates stimulation by Ets factors, including Ets1, Ets2, and GABP alpha/beta, but is also required for the transforming growth factor ( TGF)-beta response. The contrasting functions of Ets1 and Fli1 in regulation of the CCN2 gene were confirmed by suppressing their endogenous levels using adenoviral vectors expressing specific small interfering RNAs. Additional experiments using chromatin immunoprecipitation assays have revealed that in fibroblasts both Ets1 and Fli1 occupy the CCN2 promoter. TGF-beta stimulation resulted in displacement of Fli1 from the CCN2 promoter and a transient inhibition of Fli1 synthesis. Moreover, reduction of Fli1 expression resulted in up-regulation of COL1A1 and COL1A2 genes and down-regulation of the MMP1 gene. Thus, inhibition of Fli1 recapitulated some of the key effects of TGF-beta, suggesting that Fli1 suppression is involved in activation of the profibrotic gene program in fibroblasts. On the other hand, activation of the CCN2 gene downstream of Ets1 is consistent with its role in angiogenesis and extracellular matrix remodeling. This study strongly supports a critical role of Fli1 and Ets1 in the pathological extracellular matrix regulation during fibrosis and cancer.