The protein kinase c pathway plays a central role in the fibroblast growth factor-stimulated expression and transactivation activity of Runx2
The protein kinase c pathway plays a central role in the fibroblast growth factor-stimulated expression and transactivation activity of Runx2
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DOI：
10.1074/jbc.m203750200
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发表时间：
2003-01-03
影响因子：
4.8
通讯作者：
Ryoo, HM
中科院分区：
文献类型：
--
作者：
Kim, HJ;Kim, JH;Ryoo, HM
成纤维细胞生长因子（FGF）/FGF受体（FGFR）信号传导诱导Runx 2的表达，Runx 2是成骨细胞分化中的关键转录因子，但关于介导此的分子信号传导机制知之甚少。在这里，我们研究了蛋白激酶C（PKC）途径在调节Runx 2基因表达及其反式激活功能的作用。用FGF 2或FGF 4处理，或用表达在配体不存在下组成型激活的突变体FGFR 2的载体转染，强烈刺激Runx 2表达。电泳迁移率变动分析还表明，FGF 2处理增加了Runx 2与骨钙素基因启动子中的同源反应元件的特异性结合。阻断PKC完全抑制FGF 2诱导的Runx 2表达，而丝裂原活化蛋白激酶抑制剂则没有影响。FGF/FGFR刺激的6xOSE 2启动子活性也通过抑制PKC被阻断，FGF 2刺激Runx 2的DNA结合活性也是如此。PKC亚型特异性抑制剂和PKC显性负性亚型的实验表明，PKCS是参与FGF 2刺激的Runx 2表达的关键亚型之一。此外，Runx 2基因敲除细胞的实验表明，尽管PKC途径通过上调Runx 2表达在很大程度上调节FGF 2刺激的Runx 2活性，但它也在转录后修饰Runx 2蛋白，从而增加其转录活性。因此，我们首次表明FGF/FGFR信号刺激Runx 2的DNA结合和转录活性及其表达，并且这些在很大程度上受PKC途径调节。
Fibroblast growth factor (FGF)/FGF receptor (FGFR) signaling induces the expression of Runx2, a key transcription factor in osteoblast differentiation, but little is known about the molecular signaling mechanisms that mediate this. Here we examined the role of the protein kinase C (PKC) pathway in regulating Runx2 gene expression and its transactivation function. Treatment with FGF2 or FGF4, or transfection with a vector expressing a mutant FGFR2 that is constitutively activated in the absence of ligand, strongly stimulates Runx2 expression. Electrophoretic mobility shift assays also showed that FGF2 treatment increases the specific binding of Runx2 to the cognate response element in the osteocalcin gene promoter. Blocking PKC completely inhibited FGF2-induced Runx2 expression, whereas mitogen-activate protein kinase inhibitors had no effect. The FGF/FGFR-stimulated 6xOSE2 promoter activity was also blocked by inhibiting PKC, as was the FGF2 stimulation of the DNA-binding activity of Runx2. Experiments with PKC isoform-specific inhibitors and dominant negative isoforms of PKC indicate that PKCS is one of key isoforms involved in the FGF2-stimulated Runx2 expression. In addition, experiments with Runx2-knockout cells showed that, although the PKC pathway largely regulates FGF2-stimulated Runx2 activity by upregulating Runx2 expression, it also modifies Runx2 protein post-translationally and thereby increases its transcriptional activity. Thus, we show for the first time that FGF/FGFR signaling stimulates the DNA-binding and transcriptional activities of Runx2 as well as its expression, and these are largely regulated by the PKC pathway.