CCN2 is necessary for adhesive responses to transforming growth factor-β1 in embryonic fibroblasts
CCN2 is necessary for adhesive responses to transforming growth factor-β1 in embryonic fibroblasts
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DOI：
10.1074/jbc.m511343200
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发表时间：
2006-04-21
影响因子：
4.8
通讯作者：
Leask, A
中科院分区：
文献类型：
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作者：
Shi-Wen, X;Stanton, LA;Leask, A
CCN2由成纤维细胞中的转化生长因子-β(TGF-β)诱导，在结缔组织疾病中过度表达。CCN2被认为是成纤维细胞中转化生长因子β作用的下游介质；然而，CCN2在调节这一过程中的作用尚不清楚。通过使用从ccn2-/-小鼠分离的胚胎成纤维细胞，我们证明了ccn2是转化生长因子β反应的一部分所必需的。Affymetrix全基因组表达谱显示，942个转录本在ccn2-/-成纤维细胞中被转化生长因子β诱导2倍以上，其中345个在ccn2-/-成纤维细胞中未被诱导，包括前黏附和基质重塑基因。在ccn2-/-成纤维细胞中，转化生长因子β能正确地诱导Smad3反应的通用启动子，而在ccn2-/-成纤维细胞中，转化生长因子β诱导的粘着斑激酶(FAK)和Akt的激活被减少。在成纤维细胞中，FAK和Akt的激活在CCN2依赖的对转化生长因子β的转录反应中的重要性，在FAK/-成纤维细胞中不被转化生长因子β诱导，而在野生型成纤维细胞中被Wortmannin抑制。CCN2-/-成纤维细胞中AKT1的过表达挽救了转化生长因子β诱导的CCN2依赖的mRNA转录。最后，在ccn2-/-成纤维细胞中，转化生长因子β诱导的成纤维细胞与纤维连接蛋白和I型胶原的黏附显著减少。因此，在胚胎成纤维细胞中，CCN2是转化生长因子β激活粘着的FAK/Akt/磷脂酰肌醇3-激酶级联、FAK/Akt依赖的基因以及与基质黏附所必需的辅因子。
CCN2 is induced by transforming growth factor-beta (TGF beta) in fibroblasts and is overexpressed in connective tissue disease. CCN2 has been proposed to be a downstream mediator of TGF beta action in fibroblasts; however, the role of CCN2 in regulating this process unclear. By using embryonic fibroblasts isolated from ccn2-/- mice, we showed that CCN2 is required for a subset of responses to TGF beta. Affymetrix genome-wide expression profiling revealed that 942 transcripts were induced by TGF beta greater than 2-fold in ccn2-/- fibroblasts, of which 345 were not induced in ccn2-/- fibroblasts, including pro-adhesive and matrix remodeling genes. Whereas TGF beta properly induced a generic Smad3-responsive promoter in ccn2-/- fibroblasts, TGF beta-induced activation of focal adhesion kinase (FAK) and Akt was reduced in ccn2-/- fibroblasts. Emphasizing the importance of FAK and Akt activation in CCN2-dependent transcriptional responses to TGF beta in fibroblasts, CCN2 dependent transcripts were not induced by TGF beta in fak-/- fibroblasts and were reduced by wortmannin in wild-type fibroblasts. Akt1 overexpression in ccn2-/- fibroblasts rescued the TGF beta-induced transcription of CCN2-dependent mRNA. Finally, induction of TGF beta-induced fibroblast adhesion to fibronectin and type I collagen was significantly diminished in ccn2-/- fibroblasts. Thus in embryonic fibroblasts, CCN2 is a necessary cofactor required for TGF beta to activate the adhesive FAK/Akt/phosphatidylinositol 3-kinase cascade, FAK/Akt-dependent genes, and adhesion to matrix.